Indian Patents
Title of Invention

"OIL TYPE RELEASE AGENT FOR DIE CASTING"
Abstract The invention provides an oil type release agent die casting containing 70 to 98 parts by weight of a solvent having a specified flash point, 1 to 10 parts by weight of mineral oils and/or synthetic oils having a high viscosity, 15 parts by weight or less of a silicone oil, and 1 to 5 parts by weight of additives having a lubricating function, wherein the flash point of the agent is in the range of 70 to 170°C, and dynamic viscosity of the agent is 2 to 30 mmA/s or higher at 40°C, and a method for setting a mixing ratio of the solvent, a casting method, and a spraying unit for the case of using the release agent.
Full Text D E S C R I P T I O N
OIL TYPE RELEASE AGENT FOR DIE CASTINGING,
METHOD FOR SETTING SOLVENT MIXING RATIO,
CASTING METHOD, AND SPRAY UNIT
Technical Field
The present invention relates to an oil type
release agent for die casting, a method for setting a
solvent mixing ratio, a casting method using the oil
type release agent, and a spray unit. The invention is
also applicable for a plunger chip as a lubricant.
Background Art
As is well known, in die casting, to lubricate the
cavity part of a die, an oil film is formed on the
cavity surface of the die by spraying a lubricant
called as a release agent after die opening. The oil
film prevents a cavity from soldering of a non-ferrous
molten metal of such as aluminum, magnesium and zinc on
the cavity and makes possible casting continuously.
The release agents for die casting are broadly
classified into the oil type release agent and a water
soluble type relase agent. In terms of the
productivity, the safety, and the work environments,
the water soluble type relase agent has often been used
in recent years.
However, before 40 years ago, a release agent was
only oil type (hereinafter, referred to as old oil type
release agent) containing solid matters of lard, powder
and graphite with which machinery is made sticky after
use. Users diluted the agent with an economical
kerosene or solvent and sprayed the diluted agent.
However since the old oil type release agent contained
a powder, the powder scattered in the peripheral areas
of the die during casting, worsened the work
environments and deposited on the die. Thus frequent
cleaning was indispensable. The old oil type release
agent was mixed with kerosene which had a low flash
point. It was so risky as to cause a fire and thus
made automation of die casting difficult. Because of
this reason, the old oil type release agent was applied
manually, resulting in low production efficiency.
Further, since the refining degree of the kerosene was
low and trace components such as sulfur or the like
were contained, the agent might inevitably cause
adverse effects on the human body and emitted intense
oily smell. That is, the old oil type release agent
had risks of fire and explosion, was unsuitable for
automation, polluted the working environments with oil
and powders, and inevitably required periodic cleaning
works.
Because of the above described situations, the old
oil type release agent was changed to the water soluble
type relase agent with less risk of firing for
automation. It is no exaggeration to say that 99% of
release agents made commercially available are
water-soluble-type release agents now. On the other
hand, very a few oil type relase agents containing no
solid matter (hereinafter, referred to simply as highly
viscid oil type release agent) have continuously been
used. Such oil type release agents have an excellent
lubricating property. However, the viscosity is very
high (dynamic viscosity at 40°C is 100 mm^/s or higher)
and even if they are sprayed, the produced mist has a
large diameter. Therefore, the agents are unsuitable
for automatic spraying and consequently consumed much,
and the oil components of them are entrained and
gasified in the flow of molten metal to remain in the
form of gas in cast products and accordingly result in
increase of the porosity. Consequently, utilizing the
excellent lubricating property of them, the old oil
type release agents have presently been used only for
warm-up operation before applying the water soluble
type relase agent.
On the other hand, the water soluble type relase
agent free from the risk of the fire has a crucial
defective point in the capability. Since the agent is
diluted with water about 80 times as much at the time
of use, 99% of the main component are water and
therefore the agent causes Leidenfrost phenomenon on
the die at around 150°C. That is, the release agent
mist is explosively evaporated around 150°C and the die
surface is covered with a steam film. Therefore the
release agent mist, which comes next, cannot arrive at
the die surface. This causes the decrease of the
adhesion amount of active components in the release
agent on the die surface. To increase the adhesion
amount, the die temperature is kept below the
Leidenfrost temperature by spraying a large quantity of
the water soluble type relase agent while scarifying
the adhesion efficiency. As a matter of fact,
presently the spray amount is approximately the same as
the number of the tons of the locking force of a
casting machine (e.g. about 350 cc for a 350 t-machine,
about 2500 cc for a 2500 t-machine). Naturally, the
peripheral areas of the machine become dirty, the waste
fluid is much, thereby it is required much labor and
cost for cleaning and waste fluid treatment. Also,
since almost all the water soluble type relase agents
contain waxes, solidified waxes adhere to the die
surface and deposit to peripheral areas of the machine.
It requires frequent cleaning. Not only the pollution
in the peripheral areas of the machine due to the
precipitation and adhesion of the release agent's
components, but also oxidation deterioration of the
components has to be taken into consideration. Patent
Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 8-
103913) describes the use of an oxidation prevention
agent for suppressing oil component deterioration in
the water soluble type relase agent. The invention
aims the pollution prevention of a die in a rubber
vulcanization process. And it also discloses a
countermeasure for apparently decreasing stains on the
die.
Further, the die is heated to about 200 to 350°C
with aluminum molten metal every shot and thereafter
cooled to about 100 to 150°C with the water soluble
type relase agent. The temperature of the die surface
fluctuates from 100 to 200°C in every shot.
Consequently, after continuous casting for a long
duration (several thousand times for a large scale die
and several ten thousand times for a small scale die),
thermal fatigue is accumulated in the die surface, socalled
cracks are formed and finally the costly die is
broken. This is the present situation.
Further, since the water soluble type relase agent
has a strong cooling capability, the molten aluminum
injected into the cavity is cooled within a short time.
The viscosity of the molten metal is increased to
disturb the molten metal flow. Finally the molten
metal can not reach to every fine corner of the cavity.
As a result, so-called "misrun" and "shrinkage"
phenomena occur and make it impossible to produce a
complete cast product. Also, since the adhesion
efficiency of the water soluble type relase agent is
low, the oil film on the metal surface is thin.
Soldering may often occur at high temperature portions
of the die, especially thin parts like core pins.
Porosity, which decreases the strength of the cast
product, is also a problem. The cause of the porosity
is to entrain organic matters and water into turbulent
flow of the molten metal and to gasify in the casting
product. If an excessive amount of the release agent
is sprayed, the porosity increases. In the past, to
lower the porosity, Patent Document 2 (Jpn. Pat. Appln.
KOKAI Publication No. 2000-33457) disclosed a powder
type release agent having excellent releasing
capabilities.
In the above-mentioned current situation, it has
been desired to improve the disadvantageously low
adhesion efficiency of the water soluble type relase
agent, to improve the spraying property of highly
viscus oil type release agent while keeping the
excellent lubrication property, and to make it possible
to achieve "very small amount of spray", "long die lie"
and "less waste fluid".
Disclosure of Invention
The present invention aims to provide the oil type
release agent without formulating water. The oil type
release agent enables the long die, life less waste
fluid, excellent releasing lubricating property at a
high temperature and very small amount of spray. By
setting appropriate viscosity at 40°C, very small
amount of spray is achieved resulting in less vapor
scatting in air.
Also, the invention aims to provide a setting
method of a solvent mixing ratio at which the
Leidenfrost phenomenon can be avoided by setting the
mixing ratio of two kinds of solvents, or a solvent
with mineral oils and/or synthetic oils at the time of
die casting using the above-mentioned oil type release
agent for die casting.
Further, the invention aims to provide the oil
type release agent for die casting, a casting method,
and a spraying unit by which the spraying amount can be
saved as compared with that in conventional methods and
problems such as galling, flow line, metal wave, and
porosity can be solved.
1) In order to achieve the above-described
objects, the oil type release agent of the invention
(first invention) contains: (a) 70 to 98 parts by
weight of solvents having dynamic viscosity of 2 to
10 mm^/s at 40°C and having the flash point in the
range of 70 to 170°C; (b) 1 to 10 parts by weight of a
high viscosity mineral oils and/or synthetic oils
having dynamic viscosity of 100 mm2/s or higher at
40°C; (c) 15 parts by weight or less of a silicone oil
having dynamic viscosity of 150 mm^/s or higher at
40°C; and (d) 1 to 5 parts by weight of the additives
having a lubricating capability, wherein the flash
point of the agent is in the range of 70 to 170°C, and
dynamic viscosity of the agent is 2 to 30 mm^/s at
40°C.
According to the first invention, the oil type
release agent contains no water to avoid inhibition of
the lubricating property and provides lubrication
because of oil components. It is particularly
excellent in the releasing lubricating property at the
high temperature. Further, since no water is
contained, the die is not cooled with the release
agent. Thus the die life is prolonged, the scattering
of the agent in air is decreased and the die casting is
carried out free from the waste fluid. Particularly,
the agent is suitable for automatic continuous spraying
and excellent in application of a small amount of a
neat liquid and wettability. Further, according to the
first invention, the oil type release agent enables the
smaller spraying amount than the conventional agent and
the reduction of die casting problems such as galling,
flow line, metal wave and porosity.
2) The invention (the second invention) provides a
method for setting a mixing ratio of the solvent in the
oil type release agent to avoid Leidenfrost phenomenon
at the time of die casting. Two or more kinds of
solvents can be used as the solvents for mixing. The
method consists of the first, second, third and fourth
steps. The first step is to interpolate the expected
highest use temperature (S) in the following equations
(1) and (2) for calculating a needed flash point (F) of
the release agent to be formulated. The second step is
to measure flash points for three or more different
release agents having different concentrations of the
respective solvents. The third step is to make a graph
on the correlation between the % values by weight of
the solvent in each release agent and the flash point
of each release agent. The fourth step is to estimate
the % value by weight of the solvent in the release
agent to be formulated from the graph and the needed
flash point which was calculated from in the first
step.
S + 80 = L (1)
L = 4.4 x F + 36 (2)
where S denotes the highest temperature for use of a
release agent; L denotes Leidenfrost phenomenon
temperature; and F denotes the flash point of the
release agent.
According to the second invention, it is possible
to avoid Leidenfrost phenomenon at the time of die
casting using the oil type release agent.
3) The invention (the third invention) provides a
method for setting a mixing ratio of the solvent with
the mineral oil and/or synthetic oil. The purpose is
to avoid Leidenfrost phenomenon at the time of die
casting using the oil type release agent according to
claim 1. The method comprises the steps of
interpolating an expected highest use temperature (S)
in the above equations (1) and (2) for calculating an
flash point (F) of a release agent; preparing three or
more different release agents having different
concentrations of the respective solvents, mineral oils
and/or synthetic oils; investigating the flash point
for each prepared release agent; producing a graph of
the correlation of the % by weight of the solvent in
each release agent and the flash point of each release
agent; and calculating the % by weight of the solvent
in the release agent from the graph and the flash point
calculated from the equations (1) and (2).
The third invention has the same effect as that of
the second invention.
4) A casting method of the invention (the fourth
invention) involves die casting by using the oil type
release agent of the above-mentioned 1) with a release
agent application machine. According to the fourth
invention, the casting method capable of die casting
using the oil type release agent of the first invention
is provided.
5) A spray unit of the invention (the fifth
invention) is the spray system for spraying and
applying the oil type release agent according to the
above-described 1) to a die. This system comprises a
release agent spray unit with multiple spray nozzles to
apply the oil type release agent to the die surface and
a pressurized delivery unit which supplies the release
agent under a low pressure condition to the spray unit
and applies the small amount of the release agent to
the die. According to the fifth invention, it is
possible to spray the oil type release agent which is
described in the first invention.
6) The invention (the sixth invention) provides a
casting method for carrying out die casting using the
spray unit according to the above-described 4) and the
oil type release agent.
Brief Description of Drawings
FIG. 1A is a front view of a movable die employed
in Examples of the invention.
FIG. IB is a front view of a fixed die employed in
Examples of the invention.
FIG. 2 is a schematic explanatory drawing of a
spray system of the invention.
FIG. 3 is an explanatory drawing of the spray
unit, one of constituents of the spray system drawn in
FIG. 2.
FIG. 4 is an explanatory drawing of a pressurized
delivery unit, one of constituents of the spray system
drawn in FIG. 2.
FIG. 5 is a schematic explanatory drawing of an
adhesion tester to be used for measuring the adhesion
amount of releasing agent of the invention.
FIG. 6A is an explanatory drawing showing the
state that a release agent is sprayed from a nozzle for
measuring the friction force over a specimen.
FIG. 6B is an explanatory drawing showing the
state that a ring is put on a tester main body through
a test stand.
FIG. 6C is an explanatory drawing showing the
state that the friction force is measured.
FIG. 7 is a characteristic graph showing the
correlation of the flash points of various kinds of
release agents with Leidenfrost temperature and maximum
use temperature.
FIG. 8 is an explanatory drawing of an apparatus
for measuring the Leidenfrost temperature.
FIG. 9 is a characteristic graph showing the
correlation between the solvent concentration and the
flash point.
Best Mode for Carrying Out the Invention
Hereinafter the invention will be described in
detail.
(1) The oil type release agent for die casting of
the invention (the first invention) contains (a) 70 to
98 parts by weight of solvents having dynamic viscosity
of 2 to 10 mm2/s at 40°C and the flash point in the
range of 70 to 170°C; (b) 1 to 10 parts by weight of
the mineral oils and/or synthetic oils having dynamic
'viscosity of 100 mm^/s or higher at 40°C; (c) 15 parts
by weight or less of a silicone oil having dynamic
viscosity of 150 mm2/s or higher at 40°C; and (d) 1 to
5 parts by weight of additives having a lubricating
function, wherein the flash point of the agent is in
the range of 70 to 170°C, and dynamic viscosity of the
agent is 2 to 30 mm2/s at 40°C.
(2) The component (a) of the above-mentioned (1)
is a highly volatile and low viscosity component and is
to be evaporated in the die surface. In this
connection, taking the effect on the human body into
consideration, any solvents with high polarity such as
alcohols, esters, and ketones should not be used, and a
petroleum type solvent containing mostly saturated
components and a low viscosity base oil are preferable.
Examples of them are saturated solvents and low
viscosity synthetic oils which are highly refined to
suppress a sulfur component to 1 ppm or lower. The
dynamic viscosity at 40°C is specified to be of 2 to
10 mm^/s in the above-mentioned (a). When the
viscosity of the solvent is too low like 2 mm2/s or
lower, the viscosity of entire release agent becomes
too low as well. On the other hand, when the viscosity
of the solvent is too viscous like 10 mm^/s or higher,
the viscosity of entire release agent becomes too
viscous as well. Further, the ratio of the abovementioned
(a) is adjusted to be 70 to 97 parts by
weight for optimizing volatile of the entire release
agent.
(3) The flash point of the above-mentioned
component (a) of (1) is adjusted to be in the range of
70°C to 170°C because of the following reasons. That
is, to form a thick oil film on the die surface, just
like the case of a quick dry type paint, it is better
to evaporate solvents so quickly as to avoid dripping
of once adhered components from the die surface.
Therefore it is desirable to have a high evaporation
speed. However, if the evaporation speed is too fast,
Leidenfrost phenomenon may occur as seen with the water
soluble type relase agent. Therefore those solvents
having a high evaporation speed like gasoline are not
preferable. Further, if the evaporation is fast, the
flash point becomes low resulting in a high risk of a
fire accident. Accordingly, the flash point is
adjusted to be higher 43°C, which is the flash point of
old oil type release agents containing kerosene. And
it is preferable to be higher than the flash point
(70°C) of automotive diesel fuel from the practical
standpoint. Therefore, the flash point of the
composition of the invention is defined to be 70°C or
higher.
On the other hand, in the case of the die with a
high temperature, the higher flash point is preferable
to suppress the evaporation property of the release
agent. However the viscosity of the release agent also
becomes higher. If the viscosity is high, the sprayed
state of the release agent is worsened. There should
be an upper limit on viscosity. The upper limit of the
viscosity corresponds to the flash point of 170°C and
accordingly, the flash point is determined to be 170°C
or lower.
With respect to the (a) component of the abovementioned
(1), mineral oils and/or synthetic oils with
low viscosity may be added to the above-mentioned
solvents to adjust the amount to be 70 to 98 parts by
weight in total. In the case where the (a) component
is only solvent, two or more kinds of solvents may be
used. In the case of no adjustment on the basis of
Leidenfrost phenomenon, one kind of solvent may be used
alone.
(4) The mineral oils and/or synthetic oils with
high viscosity, which are the component (b) of the
above-mentioned (1), are adhered on the die surface.
The adhered components consequently make the
lubricating film thick at a temperature range of about
150 to 300°C and accordingly take a role of keeping the
lubrication. These components are required to have an
appropriate viscosity at the die temperature to prevent
dripping of the adhering oil from the die surface for
several seconds which correspond to the time from spray
to injection of molten metal. However, the die
temperature differs in a respective die machine. Even
in the same machine, the temperature differs in the
portions of the die. Therefore, the die temperature is
assumed to be 150°C or higher in the entire body and
the dynamic viscosity of the mineral oils and/or
synthetic oils with high viscosity at 40°C is adjusted
to be 100 mm2/s or higher.
Further, if the mixing amount of the (b) component
is low, the lubricating film on the die surface becomes
thin. If the mixing amount is too high, problems may
occur. One is that spraying state becomes instable.
The other is that the thick lubricating film may causes
the appearance change of a cast product partially (socalled
remaining color). To deal with these problems,
the addition amount of the component (b) is determined
to be 1 to 10 parts by weight. Examples to be used as
the component (b) are petroleum type mineral oils,
synthetic oils, and cylinder oils.
(5) The silicone oil, which is the component (c)
of the above-mentioned (1), is for fortifying the
lubricating property at a high temperature. The
component is determined to be silicone oil having a
dynamic viscosity of 150 mm^/s or higher at 40°C in an
amount of 15 parts by weight or less. This component
is also for keeping the lubricating property at a
temperature as high as about 250°C to 400°C by adhering
to the die surface. Since it is expected to keep the
lubricating property in a higher temperature range than
that of the highly viscous mineral oil of the component
(b) , the dynamic viscosity at 40°C is preferably higher
than that of the component (b), that is 150 mm^/s or
higher.
With respect to the "silicone oil" of the
component (c) of the above-mentioned (1), in the case
where a cast product is not coated, any commercialized
silicone oils including dimethyl silicone may be used.
However, in the case of coating, it sometimes becomes
difficult to form a coating with good adhesion.
Therefore dimethyl silicone is undesirable in some
cases, although its acceptability depends on the
coating amount to the die casting product. In such a
case, it is preferable to select alkyl silicone oil
having alkyl-aralkyl or a long chain alkyl group longer
than dimethyl function.
The amount of the component (c) of the abovementioned
(1) is determined to be "15 parts by weight
or less". The reason is that silicon itself or silicon
decomposition products are deposited on the die surface
to cause a bad effect on the shape of the cast product
if it exceeds 15 parts by weight. In the case where
the die is used at a low to middle temperature (lower
than 250°C) , silicon oil is not necessary to formulate
since additives having the lubricating property are
added as the component (d). In the case of the use at
a high temperature (250°C or higher) silicone oil,
which is hard to be decomposed, should be formulated.
owever, in terms of the cost, the addition amount of
the silicone oil is preferable to be low. The additive
having the lubricating property, which are the
component (d), may include, for example, an organic
molybdenum.
(6) The additives having the lubricating property,
which are the component (d) of the above (1), fortifies
the lubricating property at a low to middle
temperature. The additives may include, for examples,
animal and plant fats such as rapeseed oil, soybean
oil, coconut oil, palm oil, beef tallows oil, and lard;
esters of monohydric alcohol or polyhydric alcohols
with higher fatty acids such as fatty acid esters,
coconut oil fatty acids, oleic acid, stearic acid,
lauric acid, palmitic acid, and beef tallow fatty
acids; organic molybdenum; oil-soluble soaps and oily
waxes. The organic molybdenum is preferably, for
example, MoDDC and MoDTC, but MoDDP and MoDTP are not
preferable due to a possibility to cause reaction of
aluminum and a phosphorus component. Examples of the
oil-soluble soaps may include sulfonated salts, phinate
salts, and salicylate salts of Ca or Mg. Organic acid
metal salts can be exemplified, although the solubility
is not satisfactory.
(7) For the invention, the combinations of the
above-mentioned solvent having the described viscosity
and flash point with mineral oils and/or the synthetic
oils may be four kinds; a solvent alone, a solvent in
combination with mineral oils, a solvent in combination
with a synthetic oils, and a solvent in combination
with a mineral oil and a synthetic oil. The solvent is
not limited to one kind and two or more kinds of
solvents may be used in combination. But, petroleum
type solvents are preferable from a viewpoint of health
of workers. The above-mentioned mineral oils may
include machine oils, turbine oils, spindle oils and
cylinder oils. Synthetic esters can also be used.
(8) In the invention, the flash point of the
release agent is required to be from 70 to 170°C.
Herein the lower limit value of 70°C is for lowering
the risk of a fire. This value is higher than the
flash point of kerosene(about 40°C), which was used in
the old type release agents. Therefore, this enables
to apply the oil type release agent to the automatic
die casting process. The upper limit value of the
flash point is determined to be 170°C because of the
following reasons. That is, if mineral oils or
synthetic oils with a high viscosity (that is high
flash point) are used, the oil film adhering to the die
cannot be dried out resulting in dripping off from the
die surface. Due to the dripped-off oil portion, the
adhesion efficiency on the die surface becomes worsen
and ambient environments become worsen. Accordingly,
to avoid the problem, the flash point should be 170°C
or lower.
(9) The dynamic viscosity of the release agent at
40°C has to be 2 to 30 mm2/s. The reasons are as
follows. If the dynamic viscosity is lower than
2 mm^/s, pump wear increases at the time of applying
the release agent. If it exceeds 30 mm^/s, pumping up
of the agent at the time of application of the release
agent becomes difficult resulting in instable. If the
control becomes instable, application of 20 cc or less
becomes difficult. If the control becomes difficult,
spray amount of the release agent fluctuates every shot
and accordingly stable castability cannot be
maintained. The dynamic viscosity is more preferably
in the range of 2 to 20 mm^/s for more stable spray
amount and more finer mist formation.
(10) The oil type release agent of the first
invention has following merits against conventional
water soluble type relase agents:
1) The oil type release agent does not cause
quenching reaction;
2) The agent has a high heat resistance and antisoldering
property;
3) The agent prolongs the die life and contributes
to no waste fluid disposal;
4) The adhesion efficiency can be kept at an
appropriate oil film thickness by the flash point
adjustment from 70 to 170°C level. Thus the high
21
temperature lubricating property can be ensured;
5) It makes possible to optimize spraying
characteristics and minimize scattering of the agent in
air by setting the dynamic viscosity at 40°C within a
proper range from 2 to 30 mm2/s;
6) It reduces die casting problems such as
galling, and soldering by forming and uniform oil film
on the die surface even the spray amount is small and
the oil film is thin; and
7) It also reduces a blister problem at the time
of thermal treatment process for the die casting
product because of thin oil film.
(11) In the first invention, the spray amount of
the release agent to the die is desirably 20 cc or
less, more preferably 1 cc or less, and more preferably
0.5 cc or less for every shot on the basis of the neat
liquid. The reason for this is because if the spray
amount exceeds 20 cc, it becomes difficult to carry out
casting with no waste fluid generation, and the amount
of the gas entrained in a cast product is high level
resulting in high level of the porosity. As described,
since the spray amount is 20 cc or less, waste liquidfree
casting can be achieved. Also for the same
reason, the gas entrainment in a cast product is
decreased. Further, since neither powder nor wax is
used, too much adhesion and solid accumulation on the
die casting machine are prevented.
(12) The reason of the above-mentioned soldering
is supposed to occur with too thin oil film between the
cast product and the die surface. Particularly, the
soldering occurs frequently in the projection parts
just like core pins. Generally, it is said that the
core pins are in portions where sprayed mist is less
led and the oil film there becomes thinner than other
portions. Additionally, if the continuous casting is
started using the oil type release agent, the die
gradually becomes hot because no external cooling
function is with the agent. The adhesion amount of the
release agent on the die surface decreases with the
temperature increase, oil film is thermally
deteriorates and thus the oil film becomes thinner. To
solve such a problem, there are methods in which a
wettability improving additive is added to increase the
adhesion amount for fortifying the oil film or an
antioxidant is added to retard the thermal
deterioration of the oil film.
Accordingly, in the first invention, it is
preferable to add the wettability improving additive or
antioxidants besides the respective components (a) to
(d) of the above-mentioned (1). As the wettabilityimproving
additive, for example, 0.1 to 3 parts by
weight of acrylic copolymers or acryl-modifled
polysiloxanes with the flash point of 100°C or lower
may be added. In the above-mentioned range on the
addition, the wettability improving additive has an
adhesive effect although it is an agent for improving
the wettability. Herein, if the wettability improving
additive is added, the wettability of the release agent
to the metal surface is improved resulting in the
increase of adhesion amount on the metal surface.
Especially, if the metal surface is quite hot, the
phenomenon (Leidenfrost phenomenon) occurs. Because of
this, that lightweight components of the release agent
are bumped abruptly and oil mist droplets are kept from
wetting the metal surface. Thus the film formation on
the metal surface is inhibited. Since the wettability
is improved due to the wettability improving additive,
such a phenomenon is suppressed and the oil film is
made thicker.
(13) It is also preferable to add the
antioxidants, 0.2 to 2 parts by weight in total of one
or more kinds of antioxidants which are selected from a
group consisting of amine type, phenol type and cresol
type antioxidants. This component is added for
preventing or retarding the oxidation deterioration at
the time of high temperature operation, keeping the
thickness of the oil film, ensuring the lubricating
function, and inhibiting a soldering occurence.
Examples of the above-mentioned amine type
antioxidants are monoalkyldiphenylamine types such as
monononyldiphenylamine; dialkyldiphenylamine types such
as 4,4'-dibutylphenlamine, 4,4'-dipentyldiphenylamine,
4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine,
4,4'-dioctyldiphenylamine, and 4,4'-
dinonyldiphenylamine; polyalkyldiphenylamines such as
tetrabutyldiphenylamine, tetrahexyldiphenylamine,
tetraoctyldiphenylamine, and tetranonyldiphenylamine;
a-naphthylamine, phenyl-a-naphthylamine,
butylphenyl-a-naphthylamine, pentylphenyla-
naphthylamine, hexylphenyl-a-naphthylamine,
heptylphenyl-a-naphthylamine, and octylphenyl-anaphthylamine.
Examples of the above-mentioned phenyl type
antioxidants are 2,6-di-tert-butyl-4-methylphenol,
2,6-di-tert-butyl-4-ethylphenol, 4,4-
methylenebis(2,6-di-tert-butylphenol), 2,2-
methylenebis(4-ethyl-6-butylphenol), high molecular
weight mono-cyclic phenols, polycyclic tertbutylphenols,
BHT (butylated hydroxy toluene), BHA
(butylated hydroxy anisole). Examples of cresol type
antioxidants are di-tert-butyl-p-cresol and 2,6-ditert-
butyl-dimethylamino-p-cresol. Among the abovementioned
antioxidants, mixtures of BHT with
alkyldiphenylamines are preferable.
In the invention, antirust agents, surfactants,
preservers, defoaming agents, and other additives
(e.g., extreme pressure additives, viscosity index
improvers, cleaning dispersants, coloring agents, and
fragrant agents) may be added properly.
(14) In the invention, with respect to the abovementioned
oil type release agent containing the
respective components (a) to (d), after one to three
optional components among these components are
previously mixed to obtain a mixture and then the
remaining components may be mixed with the mixture to
obtain the release agent. Specifically, the components
(b), (c), and (d) are previously mixed to obtain a
mixture 1 and successively a user may mix the component
(a) with the mixture 1 to form the release agent. Also
the components (a) and (b) are mixed to obtain a
mixture 2 and later a user may mix a mixture 3 of the
components (c) and (d) with the mixture 2 to obtain the
release agent.
Also, among the five components including the
respective components (a), (b), (c), and (d) and
additionally a wettability improving additive or an
antioxidant (defined as a component [e]), one to four
optional components are previously mixed to obtain a
mixture. And then the remaining components may be
mixed with the previous mixture to obtain the release
agent.
(15) A low viscosity oil type release agent has
many advantageous points. However it also has
disadvantageous points due to a small amount spray of
water free type agent. The die surface is not cooled
externally. The die temperature fluctuation is slight
in one cycle of die casting. And then the steady state
is kept at a high temperature. Herein, if the
temperature is about 350°C or lower, there is no
problem at all and the advantageous points of the low
viscosity oil type release agent can be utilized as
they are. However, if the temperature is higher than
that, soldering sometimes occurs between the cast
product and the die, and it becomes difficult to carry
out continuous casting. As another inferior point, it
is sometimes required to reform a die system for
reinforcing internal cooling for the oil type release
agent where an oil type release agent is to be used for
an already existing casting machine which is operated
mainly in an external cooling manner by spraying a
large amount of the water soluble type relase agent to
a die. Further, for reasons relevant to the die
structure or product shape, inner cooling is sometimes
impossible. Therefore, it is desired to develop an oil
type relase agent provided with a high temperature
lubricating property and capable of dealing with the
Leidenfrost problem without reforming the machine.
A setting method of the solvent mixing ratio of
the invention (the second invention) is carried out
based on the above-mentioned background. That is, the
second invention is the method for setting a mixing
ratio of the above-mentioned solvent to avoid
Leidenfrost phenomenon at the time of die casting using
the oil type release agent of the first invention. Two
or more kinds of solvents are used for the abovementioned
solvent. The invention involves the first,
second, third and fourth steps. The first step is to
interpolate the expected highest use temperature (S) in
the following equations (1) and (2) for calculating the
flash point (F) of a release agent. The second step is
to investigate the flash point for three or more
different release agents having different
concentrations of the respective solvents. The third
step is to make a graph of the correlation of the %
value by weight of the solvent in each release agent.
The fourth step is to calculate the % value by weight
of the solvent in the release agent to be formulated
from the graph and the flash point calculated from the
equations (I) and (2).
S + 80 = L (1)
L = 4.4 x F + 36 (2)
where S denotes the highest temperature for use of a
release agent; L denotes Leidenfrost phenomenon
temperature; and F denotes the flash point of the
release agent.
The setting method of the solvent mixing ratio of
the third invention is the method for setting the
mixing ratio of the above-mentioned solvents with the
above-mentioned mineral oil and/or synthetic oil to
avoid Leidenfrost phenomenon at the time of die casting
using the oil type release agent of the first
invention. The invention involves the first, second,
third and fourth steps. The first step is to
interpolate the expected highest use temperature (S) in
the above-mentioned equations (I) and (2) for
calculating the flash point (F) of a release agent.
The second step is to investigate the flash point for
three or more different release agents having different
concentrations of the respective solvents, mineral oils
and/or synthetic oils. The third step is to make a
graph of the correlation of the % value by weight of
the solvent in each release agent. The fourth step is
to calculate the % value by weight of the solvent in
the release agent from the graph and the flash point
calculated from the equations (1) and (2).
(16) Next, the Leidenfrost phenomenon of the
above-mentioned (15) is described below.
When the oil type release agent is brought into
contact with a hot die, lightweight hydrocarbon
components in the agent bump abruptly. Those
hydrocarbon components make a rising gas current and
other parts of the hydrocarbon components are in the
air as oil droplets. Because of the rising gas
current, oil droplets float up from the die surface to
worsen the contact of the droplets with the die
surface. As a result, the heat is not transmitted to
the oil droplets to make the evaporation speed slow
down. Since active components of the oil droplets are
inhibited from the adhesion on the die, the adhesion
amount is decreased to worsen the releasing property.
This phenomenon is called the Leidenfrost phenomenon
and it has been known well in the case of water soluble
type relase agents. This phenomenon occurs around 150
to 200°C in the case of water soluble type relase
agents, while the phenomenon occurs at 350°C or higher
in the case of the oil type release agent invented.
This was found based on the investigations carried out
for the invention.
The present inventors have investigated the
temperature at which the Leidenfrost phenomenon occurs
in an experimental scale. In addition, the inventors
studied the highest use temperature in an actual die
casting machine and the flash point of release agent.
The results are shown in FIG. 7. As shown in FIG. 7,
when the flash point rises, the Leidenfrost phenomenon
temperature goes up and the highest useable temperature
becomes higher in the actual machine. In this case,
the temperature, at which the Leidenfrost phenomenon
occurs, is defined as a point at which the evaporation
speed becomes the slowest. But the evaporation speed
is found to be retarded when the temperature is still
lower before that point. That is, it can be said that
at the temperature lower than the Leidenfrost
30
phenomenon temperature by about 80°C, the release agent
reaches its practical use limit. From FIG. 7, the
following correlation can be assumed:
where S denotes the highest temperature for use of the
oil type release agent (°C); L denotes the Leidenfrost
phenomenon temperature (°C); and F denotes the flash
point (°C) .
As assumed from FIG. 7, if the Leidenfrost
phenomenon point of the release agent is increased, the
highest practical use temperature can be raised.
Herein, there are two methods to increase the highest
practical use temperature. A former method is to
increase the flash point of the agent to confirm the
practical application by using an actual machine. The
latter method is to increase the Leidenfrost phenomenon
temperature by increasing the flash point. However, a
large scale experiment is required to confirm the
practical applicability by using the actual machine.
Since the method for measuring the Leidenfrost
phenomenon temperature in the laboratory scale is
easier, the latter method is employed. However, if the
flash point is increased and the spray amount is
increased too much, the fume becomes dense at the time
of spray and therefore, it is required to carry out the
experiments carefully.
31
Next, the measurement method of the Leidenfrost
phenomenon temperature will be explained with reference
to FIG. 8. For the measurement, the apparatus of
FIG. 1 is employed as described in Takeo TAKASHIMA,
Hiroshi SHIOTA, "Study on Evaporation of Oil-in-Water
type Emulsion Droplets on Heated Face", Transactions (B
edition) of The Japan Society of Mechanical Engineers,
Vol. 70, No. 700 (2004-12) No 03-1248.
At first, a saucer 51 made of brass is put on a
heater 52. The saucer has a cylindrical and saucerlike
structure with a diameter of 60 mm, a height of
30 mm, and a curvature radius R of 200 in the upper
face, and a depth of 4 mm in the center. The saucer 51
is covered with an insulator 53 and a transformer 54 is
connected to the heater 52. A thermocouple 55 is
embedded under the center in 2 mm depth of the saucer
51 and connected with a temperature recorder 56.
Further, a video camera 57 is installed for
photographing the bumping state. Also, a release agent
is put in a syringe 58 made of polyethylene and
equipped with a thin tube. The tip end of the thin
tube is set above the center of the saucer at 40 mm
height. In this case, the diameter of a droplet 59 is
about 2.7 mm. When the temperature of the saucer 51
reaches a prescribed temperature, one droplet 59 at a
room temperature is dripped. And then the evaporation
time is measured by a stop watch. Also, the state of
32
the droplet is observed by the video camera 57. The
above-mentioned observation is carried out at every
10°C and the graph of the correlation between the
temperature and the evaporation time is produced. The
temperature, at which the evaporation time is the
longest, is defined as Leidenfrost phenomenon
temperature.
(17) The above-mentioned release agent will be
described more in detail. The oil type release agent
is free from water, powder or emulsifier. It is
understood that if no water is contained, the die is
less cooled and the thermal fatigue is minimized and
therefore the die life is remarkably improved. For
example, according to a small die casting product
obtained by using an actual die casting machine, repair
and maintenance of the die are required every
20000 times shot in the case of a water-soluble agent.
However no repair of the die is required even after
320000 times shot in the case of the oil type agent.
And it is thus proved the life is at least 16 times as
long. The economic effect is equivalent to the cost
down of several million yen in the case of small scale
of 350 ton machine. Further, since no water is used
and small amount blowing is made possible, no waste
fluid is discharged and the waste liquid treatment cost
is also remarkably saved. Further, because a very
small amount of spray, the smoke or fume is extremely
decreased and the work environments are remarkably
improved.
Further, since the oil type release agent of the
invention contains no emulsifier, which is
indispensably employed for all water-soluble release
agents. The oil type release agent is advantageous in
the waste liquid treatment. The oil type release agent
is also suitable for avoiding endocrine disrupting
substance problems. Further, since the release agent
of the invention contains no powder, the agent is also
advantageous in suppression of the staining of
apparatus, prevention of quality alteration of the
release agent due to precipitation during storage, and
retention of surface luster without damages on the
surface of a cast product with a powder.
(18) A casting method of the invention (the fourth
invention) is for die casting by using the oil type
release agent for the die casting of the first
invention and the release agent spray unit. According
to the invention, die casting is made possible by using
the oil type release agent. FIG. 1A shows the front
view of a movable die to be used in the invention and
FIG. IB shows the front view of a fixed die part of the
die to be used in the invention. The above-mentioned
die is composed of the movable die 1 and the fixed die
2 and the movable die I is provided with an upper slide
3, a lower slide 4, and a movable core 5. The
reference numeral 6 in the figure denotes a guide pins;
the reference numeral 7 denotes surface pins; the
reference numeral 8 denotes ejector pins for runners;
and the reference numeral 9 denotes a fixed core.
(19) A spraying system of the invention (the fifth
invention) is a device for applying the oil type
release agent for the die. This system comprises a
spray unit provided with plural nozzle tubes for
spraying the release agent to the die and a pressurized
delivery unit to send the release agent to the spray
unit which is used at a low pressure to apply a small
amount of the release agent to the die. The spray
system is provided with a spray unit 22 having a
plurality of spray nozzles 21 as shown in FIG. 2. A
tube 23 for air introduction into which air is
introduced and a tube 24 for release agent introduction
into which the oil type release agent for the die
casting is introduced are connected with the spray unit
22. A tank 25 for storing the oil type release agent
is connected to the tube 24 for release agent
introduction via a pressure reducing valve 26 for
pressure sending the release agent and a pump 27 for
pumping the release agent. The pressurized delivery
unit comprises the tank 25, the reducing pressure valve
26 for the release agent, the pump 27 for pumping the
release agent, and a release agent pressure sending
hose, which is not illustrated here. The reference
numeral 29 in the drawing shows the die having a cavity
part 28.
(20) In the case where the above-mentioned oil
type release agent is employed by the already existing
spray system for a water soluble type relase agent,
that is, a unit type spray system having a large number
of nozzles, there has been the problems mentioned
below:
1) Since the oil type release agent has a higher
viscosity than the water soluble type relase agent, the
spraying amount per every nozzle is not well balanced;
and
2) Fine adjustment of the spraying amount is
difficult.
Thus, in the case where the oil type release agent
is automatically applied to carry out die casting by
using the already existing spray system for a water
soluble type relase agent without reforming the system,
problems such as galling, flow line, metal wave, and
much gas remaining in a product (porosit) are
frequently caused. To deal with these problems, it is
required to evenly apply the release agent to the die.
In the spray unit of the invention, spray unit
comprises a spray unit main body, tubes for air
introduction and tubes for release agent introduction.
Each of air tubes and agent tubes is connected with the
spray unit main body as a set of tubes, respectively.
As a pair of multiple sets of tubes are arranged face
to face at two or more points, so that the release
agent from the spray nozzles can be sprayed evenly to
the die.
Spray unit 22 has a structure shown in FIG. 3.
The reference numeral 31 in the drawing denotes a spray
unit main body. Tubes 23a and 23b for air introduction
branched from the tube 23 for air introduction are
connected to both ends of the spray unit main body 31.
Tubes 24a, and 24b for release agent introduction
branched from the tube 24 for release agent
introduction are connected to both sides of the spray
unit main body 31. Accordingly, the set of the
branched tubes 23a and 24a are arranged on the side of
tubes 23b and 24b as a pair. In FIG. 3, the sets of
tubes for air introduction and for release agent
introduction are arranged on the opposite to each other
at two points. However the pair of tubes may be
arranged on the opposite to each other at three or more
points.
The reason is described below for the arrangement
of the pair of tubes on the opposite to each other at
two or more points is as follows.
(21) The spray unit for the water-soluble release
agent has a large number of spray nozzles having
release agent application nozzles. Conventionally,
there is only one set of a supply port (a tube for
release agent introduction) and an air supply port (a
tube for air introduction). In the case where the
spray unit is employed for applying the oil type
release agent without any modification, the release
agent is applied more than necessity from the spray
nozzle due to near position to the set of the supply
port for the oil type release agent and air supply
port. This is because a small amount of the oil type
release agent is used and the viscosity of the oil type
release agent is higher than that of water soluble type
relase agent. On the other hand, the spray amount is
less than necessity from the spray nozzles which are
located at a remot portion from the introduction tubes
and thus it is made impossible to evenly apply the oil
type release agent to the die. Accordingly, a pair of
the tubes sets for release agent introduction and for
air introduction are arranged face to face at two or
more points, so that pressure is applied evenly by the
respective spray nozzles, and the oil type release
agent and air are supplied evenly to the nozzles.
Consequently, it is made possible to evenly apply a
small amount of the oil type release agent for the die
surface.
In the spray system of the invention, the
pressurizing delivery unit may comprise a tank for
storing the oil type release and a delivery hose for
in the tank is set between the upper limit position at
the time when the spray nozzle is in waiting mode and
the lower limit position at the time when the release
agent is sprayed.
(22) The pressurizing delivery unit 40 has a
structure as shown in FIG. 4. The reference numeral 41
in FIG. 4 shows the die casting machine. The movable
die 1 and the fixed die 2 shown in FIG. 1 are arranged
at a distance from each other in the die casting
machine 41. The tank 25 storing the oil type release
agent is connected to the spray unit 22 via a release
agent pressure sending hose 42. Although not
illustrated, a pressure reducing valve and a pump for
pumping up the release agent show in FIG. 3 are
installed in the tank 25. The spray unit 22 is made
movable up and down by a supporting pole 43 which is
movable up and down (in the direction shown as the
arrow Y). The supporting pole 43 is guided by s
supporting pole 44 mounted on a part of the die casting
machine 41 and a transverse bar 45 joined to the
supporting pole 44.
Following are reasons why the top level of the
agent face in the tank is set in the above-mentioned
manner. That is, to apply a small amount of the oil
type release agent, it is necessary to send the agent
at a low pressure by the pump to the spray unit and the
sending pressure of the oil type release agent is as
extremely low as 0.02 to 0.05 MPa. Therefore, if a
very small amount of air, which is mixed in the release
agent, is sent together with the agent by pump, a
rather large air layer, so-called air spot, is formed
at the highest point in the tube. This air spot
interrupts the flow of the release agent to lose the
stability of the spraying amount. As a result, in a
mass production of die casting products, the
repeatability precision of the spray amount control of
the release agent is worsened and the quality of die
casting products is affected adversely.
On the other hand, it is found that this spray
control problem can be solved by setting as mentioned
before. The top level of the agent face in the tank
should be set between the upper limit position (the
position is higher than the tank) L]_ at the time when
the spray nozzles are in waiting mode and the lower
limit position L.2 at the time when the release agent is
sprayed (reference to FIG. 4). That is, during the
time when the spray nozzles are set at the lower face
position in the waiting mode, the pressure is increased
corresponding to the liquid pressure (the height of the
release agent) in relation to the tank position, the
flow rate of the release agent is increased
accordingly, and the accumulated air also becomes easy
to flow to decrease the air spots. However, if the tip
end position of the nozzles is set to be further lower
than the above-mentioned position, the air flows out
faster, but a large quantity of the release agent is
also discharged. It causes a difficulty in applying a
small amount of the agent. Accordingly, it is required
to set the lower limit position. On the other hand,
the pressure is low during the time of the waiting mode
of the spray nozzles at the upper level position, so
that the flow of the release agent is decreased and air
hardly flows out of the tip of the nozzles. Further,
when the nozzle is at higher than that, the liquid
pressure of the release agent is lowered, finally the
release agent tends to go back to the tank, and air is
sometimes sucked from the tip of the nozzles. Because
of that, the upper level position of the spray nozzles
is also limited. The position of the tank for the
release agent is set between the lower limit and the
upper limit, so that small amount spray can be achieved
and the air spot problem can be solved simultaneously.
Further, it is made possible to supply the release
agent to the spray unit by a minimum delivery pressure
of the necessity. Owing to this effect, with respect
to the spray amount, application in an amount as low as
0.1 to 0.2 cc per one nozzle is made possible. And
even and small amount spray to the die surface can be
carried out.
Hereinafter, Examples of the invention will be
described. However, it is not intended that the
invention be limited to the illustrated Examples.
(I) Examples 1 to 5 and Comparative Examples 1 to 3
(A) Components and results of measurement tests
The following Table 1 shows the components of
Examples 1, 2, 3, 4, and 5, physical values, results of
the adhesion test, and results of a friction test.
Also, the following Table 1 shows Comparative Examples
1 to 3 the components of water soluble type relase
agents produced by the applicant of the invention: that
is, a water-soluble pigment release agent (trade name:
Lubrolene A-704), a water soluble type relase agent
(trade name: Lubrolene A-201), and a water soluble type
relase agent (trade name: Lubrolene A-1609), physical
values, results of the adhesion test, and results of
the friction test.
(B) Production method
After mixing a high viscosity mineral oil, a
silicone oil, a rapeseed oil and an organic molybdenum
at ratios shown on the basis of % by weight in Table 1,
the mixture was heated to 40°C and stirred for
10 minutes. The mixture was further mixed with a
solvent in the amount on the basis of % by weight shown
in Table 1 and again mixed for 10 minutes to produce
agent and the balance, 0.05% by weight, was a wax, an emulsifier
In Table I,
Solvent: trade name: Shellsol TM, manufactured
by -Shell Kagaku K.K.
High viscosity mineral oil: trade name: Bright
stock, manufactured by Japan Energy Corporation,
Fats: Rapeseed oil manufactured by Meito Yushi
Co., Ltd.
Silicone: trade name: Release Agent TN
manufactured by Asahikasei Wacker Silicone Co., Ltd.
Organic molybdenum: trade name: Adeka 165,
manufactured by Asahi Denka Kogyo
(C) Measurement method of flash point
The flash point of each specimen was measured by
Pensky-Martin method according to JIS-K-2265
(D) Measurement method of dynamic viscosity
The dynamic viscosity at 40°C was measured
according to JIS-K-2283.
(E) Measurement method of adhesion amount
(E-l) Preparation
As a specimen, an iron plate (SPCC,
100 mm x 100 mm x 1 mm thickness) was baked at 200°C for
30 minutes in an oven, cooled overnight in a
desiccator, and the plate weight was measured to 0.1 mg
order.
(E-2) Spray of the oil type release agent
The operation of the adhesion tester shown in
FIG. 5 was as follows.
44
At first, an electric power source temperature
adjustment apparatus 12 was set at a prescribed
temperature and a stand 14 for holding a specimen was
heated by a heater 13. Herein, when the first
thermocouple 17 reached the set temperature, the iron
plate 16 as a specimen was put on a metal fitting 15
for supporting a specimen and the second thermocouple
18 was brought into firm contact with the iron plate
16. After that, when the temperature of the iron plate
16 reached the prescribed temperature, a prescribed
amount of each release agent 19 was automatically
sprayed to the iron plate 16 by the spray 20. Then,
the iron plate 16 was taken out and stood vertically in
air for a fixed time, to allow an oil dripping off from
the iron plate 16.
(E-3) Measurement method of adhesion amount
After keeping the iron plate 16 with coated
ingredients in an oven at a prescribed temperature for
a prescribed period, the plate was taken out. The
plate was cooled by air, and further cooled in the
desiccator for a prescribed period. After that, the
weight of the iron plate 16 bearing the coated
ingredients was measured up to 0.1 mg order. And
the adhesion amount was calculated from the weight
change of the iron plate considering a blank test
result.
(E-4) Test condition
Tester: Adhesion amount tester (manufactured by
Yamaguchi Giken Co., Ltd.)
Measurement conditions: as described in the
following Table 2.
Reference to FIGS. 6A to 6C. At first, a friction
testing stand 2 (SKD-61 model, 200 mm x 200 mm x 34 mm)
having a thermocouple 1 attached to an automatic
pulling tester (trade name: Lub Tester U) manufactured
by MEC International Co., Ltd. was heated to a
prescribed temperature by a commercially available
heater. Next, as shown in FIG. 6A, the testing stand 2
was vertically stood and a release agent 4 was sprayed
by a nozzle 3 under the conditions shown above in the
adhesion test. Immediately after that, the testing
stand 2 was horizontally put on the tester main body 5
and a ring 6 (made of S45C, inner diameter 75 mm, outer
diameter 100 mm, and height 50 mm) manufactured by MEC
International Co., Ltd. was put on the center (refer to
FIG. 6B). Successively, 90 cc of aluminum molten metal
7 (ADC-12, at 670°C) , which was melted at a melting
furnace for a ceramic art use, was poured into the ring
6. The molten metal was cooled for 40 seconds to be
solidified. Further, an 8.8 kg weight 8 made of iron
was immediately and calmly put on the solidified
aluminum (ADC-12). Then, the ring 6 was pulled in the
direction shown as the arrow X by a gear of the tester
to measure the friction force (refer to FIG. 6C).
(F-2) Friction force measurement conditions
The friction force measurement conditions were as
shown in the following Table 3.
The test results were shown in Table 1 on flash
point, dynamic viscosity, adhesion amount (300°C), and
friction force at 300°C and 350°C for the abovementioned
Examples and Comparative Examples.
It is confirmed by the tester manufacturer that
the results have an excellent correlation with those
carried out by actual die casting machines. 10 Kgf
value in the tester corresponds to an allowable maximum
level of the releasing property in the actual machines.
A higher value than 10 Kgf in the tester suggests
troubles such as soldering and galling in the actual
machines.
According to the results of the functional
comparative test, the oil type release agents of
Examples 1 to 5 were found having higher adhesion
amounts, lower friction forces and better releasing
capability than the water soluble type relase agents of
Comparative Examples 1 to 3. Also, even at a high
temperature of 350°C, at which the soldering occurred
with water soluble type relase agents, the oil type
release agents were found having sufficiently excellent
releasing capability.
(II) Examples 6 to 11 and Comparative Examples 4 to 7
Hereinafter, release agents of Examples 6 to 11
containing a wettability improving additive will be
described with reference to release agents of
Comparative Examples 4 to 7.
(A) Components and test results
The following Table 4 shows components physical
values, results of adhesion test, and results of
friction force test of the oil type release agents of
Examples 6, 7, 8, 9, 10, and 11. The following Table 5
shows physical values, components, results of adhesion
test, and results of friction test for the oil type
release agents of Comparative Examples 4, 5, and 6 and
the water soluble type relase agent (trade name:
Lubrolene A-1609, manufactured by AOKI SCIENCE
INSTITUTE Co., Ltd.) of Comparative Example 7.
*1: Trade name: EFKA-3236 modified polysiloxane,
manufactured by Wilbur-Ellis Company
*2: Trade name: EFKA-3778 acrylic copolymer,
manufactured by Wilbur-Ellis Company
Others components are the same as those shown
*1 and *2 are the same as those shown in
Table 4. The other components are the same
as those shown in Table 1.
*3: A water soluble type relase agent and the
balance, 0.05% by weight, was a wax, an
emulsifier or the like.
(B) Production method
Same as described in Example 1, except that the
wettability improving additives were mixed before the
solvents were added.
(C) Measurement method of flash point
The measurement was carried out by Cleveland Open
method for Example 9 and Comparative Example 6, and by
Pensky-Martin method for Examples 6, 7, 8, 10, and 11
and Comparative Examples 4 and 5.
(D) Measurement method of dynamic viscosity
Same as described in Example 1.
(E) Measurement method of adhesion amount
The preparation and measurement of the adhesion
amount were the same as described in Example 1, and the
testing conditions were as shown in the following
(F) Measurement method of friction force
The friction force test method was the same as
Example 1 and the friction force measurement conditions
were the same as described in Table 3.
(G) Collective results of the measurement (Effect of
wettability improving additive)
In comparison of Example 6 (containing the
wettability improving additive) with Comparative
Example 4 (without the wettability improving additive);
Example 7 (containing the wettability improving
additive) with Comparative Example 5 (without the
wettability improving additive); and Example 8
(containing the wettability improving additive) with
Comparative Example 6 (without the wettability
improving additive), the wettability improving
additives were found considerably increasing the
adhesion amounts and lowering the friction force.
Release agents cannot necessarily be sprayed
evenly to die surface of actual machine. There are
some concealed die portions which are wetted with a
small amount of oil droplets, in which cases excellent
releasing property can be exhibited by the release
agents of Examples 6 to 11 with which show a high
ability in the adhesion amount. The wettability
improving additives are effective not only in the
release agents of Examples 6, 7, 8, and 10 having
viscosity in the range of 3 to 5 mm^/s. In addition,
the additives are also effective in the release agent
of Example 9 with viscosity as high as 24 mm2/s. The
water soluble type relase agent of Comparative Example
7 for reference has friction force of 10 kgf at 300°C,
53
which is a limit for use, while the oil type release
agents have friction force in the range of 1 to 3 at
300°C kgf and they are usable.
The release agents of the invention containing the
wettability improving additives are effective to
increase the adhesion amount on the die surface.
Sometimes, the release agent mist is hardly spread to
result in occurrence of soldering at fine parts of the
die. The release agent having high adhesion property
is highly possibly to avoid such a problem. It can be
said that the oil type release agents of the invention
are excellent from this point of view. Also, since the
adhesion efficiency is high, the release agents are
usable in a small amount without making the adhered oil
film thick. They are also usable as release agents
with low viscosity and excellent in spraying property
even if diluted with the above-mentioned component (a).
(Example 12)
Next, the spray unit for evenly applying the oil
type release agents of the invention will be described.
The unit is as explained above. The casting qualities
were compared in Example 12 by using an actual machine.
The following Table 7 shows the properties of
products obtained by aluminum die casting using the
release agents of Examples 13 to 16 and Comparative
Examples 8 and 9 and the above-mentioned spray unit.
In this case, the release agent of Example 4 was used
for Examples 13 and 14; the release agent of Example 6
was used for Examples 15 and 16; the release agent of
Comparative Example 7 was used for Comparative Example
8; and the release agent of Comparative Example 4 was
used for Comparative Example 9. As shown in FIG. 1,
the die employed in Example 12 was able to make two
products at the same time and had a casting structure
composed of upper and lower slides in a cavity part
which was formed with movable and fixed dies.
The spray of the oil type release agent to the
cavity section was carried out by attaching the spray
unit of the invention to an automatic spray unit.
Also, exclusive spray unit (shown in FIG. 3) and a
pressurizing delivery unit (shown in FIG. 4) were used
for oil type release agents. Further, the release
agents were pumped up by a pump and sent at a low
pressure of 0.02 to 0.05 MPa to the spray unit. The
oil type release agents were sprayed by air used in a
plant and applied in a small amount to the die surface.
*2: Employing spray unit for water-soluble release agent + pressurized delivery unit
shown in FIG. 4.
*3: Employing spray unit for water-soluble release agent + spray unit shown
in FIG. 3 + pressurized delivery unit shown in FIG. 4.
*4: Employing wettability improving agent and spray unit for water-soluble
release agent.
*5: Employing spray unit apparatus for water-soluble release agent.From the results shown in Table 7, the release
agents (the former) of Examples 13 to 16 were found to
be better or excellent in following points as compared
with the release agents (the latter) of Comparative 8
and 9:
1) Excellent releasing performances of galling,
soldering, flow line, metal wavy and occurrence of burr
presumably due to excellent spreading property of the
agent;
2) Less porosity in the die casting product;
3) Small spray amount which contributes to short
spraying time;
4) Excellent controllability of the delivery
pressure which results in stable spray amount per each
nozzle;
5) Less daily work in controlling spray amount
because of less fluctuation of the spraying amount;
6) Same or better in the necessity of daily
maintenance, retention of size precision, and
occurrence of cracking in dies; and
7) Excellent in the maintenance of dies and
precision.
It is not intended that the invention be limited
to the above illustrated embodiments. Modifications
and substitutions to specific process conditions and
constitutional components can be made without departing
from the spirit and scope of the invention. For
58
example, in the above Examples, although the tube for
air introduction and the tube for release agent
introduction are arranged face to face at two points,
these tubes may be installed face to face at three or
more points. In this connection, it is desired that
these tubes are arranged on the opposite to each other
as evenly as possible. With arrangement in such a
manner, the release agent can be sprayed more evenly to
the die from the tip ends of spray nozzles. The wavy
patterns, gas amount left in a product, and application
amount can be improved.
In the above-mentioned Example 12, the tip end
position of the oil face in the tank at the time of
stopping spraying is set between the upper face
position at the time when the spray nozzles are in
waiting mode and the lower limit position at the time
when the release agent is sprayed by the spray nozzles.
However, it is not limited as described in this
Example. The tank for the release agent may not be
installed between the positions and the tip end
position 13 of the oil face of the release agent may be
set at the position by applying the pressure. With
such conditioning, in the case where the release agent
is not sprayed, the stopping position (rising limit) of
the spray unit is above the oil surface position and
therefore, the release agent does not drip. On the
other hand, in the case where the release agent is
59
going to be applied, since the spray units are stopped
at stopping position, which is the lower limit of spray
unit, the pressure is sufficient for causing
spontaneous drip of the oil type relase agent.
Accordingly, no air spot is formed in hydraulic hoses
and spraying of the oil type relase agent by air
pressure in a plant can be carried out evenly with
suppressed unevenness.
(Ill) Example 17 and Comparative Examples 10 and 11
Hereinafter, Example 17 will be described together
with Comparative Examples 10 and 11.
(A) Components and test results
The following Table 8 shows the components, mixing
ratios, and test results of oil type release agents of
Example 17 and Comparative Examples 10 and 11.
Trade name: Lasmit BHT, manufactured by
Daiichi Kogyo Seiyaku Co., Ltd.
Trade name: HiTEC-569, manufactured by
Afton Chemical and the other components are
the same as those shown in Table 1.
Impossible to measure since solidified
aluminum did not slide on the test stand and
deposited.
61
(B) Production method
The production was carried out as described in
Example 6, except that the antioxidant was used in
place of the wettability improving additive of
Example 6.
(C) Measurement of flash point
The flash point of each agent was measured in the
same manner as described in Example 1.
(D) Measurement of dynamic viscosity
The dynamic viscosity of each agent was measured
in the same manner as described in Example 1.
(E) Laboratory oxidation test, ROBT method
According to JIS-K-2514, each agent was sampled
into a closed type rotary pump and oxygen gas was then
sealed. Oxidation was carried out at 150°C and the
time taken to abruptly decrease oxygen pressure was
measured.
(F) Measurement method of friction force
The testing method of friction force and the
measurement conditions were the same as described in
Example 1.
(G) Collective results of measurement (Effect of
antioxidant)
In Example 17 and Comparative Examples 10 and 11,
the flash point (°C) , the dynamic viscosity (mm^/s) at
40°C, the laboratory oxidation test, the laboratory
friction force test at 350°C and 400°C, and measurement
of continuous castability using an actual die casting
machine were carried out to find the results as shown
in Table 8.
In comparison of the results of Example 17
(containing antioxidant) with those of Comparative
Example 11 (containing no antioxidant), from a
viewpoint of the laboratory test, the measured value
(deterioration time) of Comparative Example 11 was
240 minutes, meanwhile it was 890 minutes for Example
17, showing durability as much as about 4 times and
less deterioration. Accordingly, in the case of
Example 17, it was confirmed that the antioxidants
suppressed the oxidation deterioration of the oil type
release agent.
From a viewpoint of the friction force test, the
friction force of Comparative Example 11 was 5 kgf at
350°C, which is sufficiently low for practical use.
However the agent caused soldering at 400°C and
deposited. On the other hand, in Example 17, the
friction force is as low as 9 kgf even at 400°C. The
agent was found apparently excellent in the high
temperature lubricating property as compared with the
agent of Comparative Example 11. Accordingly, in the
case of Example 17, it was confirmed that the
antioxidant showed the effect and prevented the
soldering.
According to the above mentioned two kinds of
experiments, it is assumed that the antioxidants can
delay the oxidation deterioration of the components of
the oil type release agent at a high temperature.
Because of this delay, the antioxidants contribute to
retention of the oil film thickness. Thus the friction
resistance is kept at low level because of the thick
oil film.
On one hand, when the release agent of Comparative
Example 11 was evaluated using an actual die casting
machine, the soldering occurred at the 10th time to
make continuous casting impossible. In the case of
Example 17, continuous casting could be continued 220
or more times. As a result, it was confirmed that the
antioxidants contributed to decrease of soldering and
increase of the times of the continuous casting. In
the case of the actual machine employed for this case,
the temperature of the core pin was 410°C immediately
after the product was taken out. However, in the case
of combination of the actual machine and Comparative
Example 11, the continuous casting at 380°C was the
limit. According to the results, it can be said that
addition of the antioxidant improves the durability to
30 degree higher side.
Further, to ensure the lubricating property at low
to middle temperature areas, the organic molybdenum was
added in Example 17 and Comparative Example 11. On the
other hand, no organic molybdenum was added in
Comparative Example 10. The oxidation stability of
Comparative Example 11 was slightly improved as
compared with that of Comparative Example 10. Friction
at 350°C was slightly decreased in the laboratory
friction test. The number of casting times was
slightly increased. Accordingly, the results showed
the organic molybdenum had an auxiliary effect on
oxidation prevention. However the effect was not so
much significant as compared with those of phenol type
or amine type antioxidants.
(Example 18)
Hereinafter, a method of setting mixing ratio of a
solvent according to the second invention will be
described.
As being made clear from FIG. 7, the flash point
of a release agent can be changed easily to adjust the
Leidenfrost phenomenon temperature. The investigations
carried out by the inventors for accomplishing the
invention made it clear that there are correlations of
the Leidenfrost phenomenon temperature L with the flash
point F (reference to the equation (1)) and the highest
use temperature (S) (reference to the equation (2)) of
oil type release agents. The correlations may be
defined as follows:
1) The Leidenfrost phenomenon temperature L was
calculated by interpolating an expected value of the
highest use temperature S in the equation (1). And
then the calculated temperature L was interpolated in
the equation (2) to calculate the flash point F
required for the oil type release agent.
2) Next, three types of release agents (specimen
I, specimen 2, specimen 3) were produced by changing
mixing ratios of the solvent and mineral oils in the
compositions. The Table 9 shows the components and
flash points of those three specimens. The recommended
mixing ratios were 80%, 70%, and 60% of the solvent.
3) After that, the flash points of these three
kinds of release agents were measured and as shown in
FIG. 9, a graph was produced for the correlation of the
solvent (%) and the flash point.
4) Further, the needed solvent (% by volume) was
calculated using the flash point (F) which was
calculated as described in 1) from the graph.
5} Next, a light component (the low viscosity
mineral oil and/or the synthetic oil) was calculated
from the balance calculated by subtracting the ratios
of the solvent and the additive.
In the manner as described above, in Example 18,
the mixing ratio of the solvent and the mineral oil was
properly set to avoid the Leidenfrost phenomenon.
In Example 18, the case of using the solvent and
mineral oil was described. However the invention may
include the case of using a solvent and a synthetic
oil; or the case of using a solvent, a mineral oil, and
a synthetic oil; or the case of using two kinds of
solvents.
In the above-mentioned Example, the oil type
release agent was described based on the first
invention. However the combination of the respective
components, mixing ratios and spray condition may
properly be set to use the following oil type release
agent. That is, the oil type release agent contain 50
parts by weight or more in total of 1 or more kinds of
components selected from a group consisting of
solvents, mineral oils, synthetic oils, fats and oils,
aliphatic acids, and aliphatic acid esters, 40 parts by
weight or less of silicone oil, and additives having
lubricating function, has the flash point of 50 to
250°C and dynamic viscosity of 2 to 50 mm2/s at 40°C.
With such a constitution, quenching is not caused
unlike a conventional case and the agent as the oil
type relase agent has high heat resistance scarcely
causes soldering, resulting in possibility of
prolongation of the die life. Also, the use of such an
oil type release agent makes it possible to form an
even and thin film on the die surface with a small
amount, galling and soldering of the die casting
product on the die and blistering at the time of
thermal treatment can be suppressed. The types and
properties of the respective components are as
described in the case of the above-mentioned oil type
release agents.
Industrial Applicability
The oil type release agent of the invention is
suitable for lubricating die surfaces by spraying a
lubricant during die casting and for lubricating
plunger chips at the time of pouring molten metal. The
oil type release agent of the invention is suitable for
automatic continuous spray of undiluted agent liquid
with small amount in the continuous production.





We claim:
1. An oil type release agent for die casting containing: (a) 70 to 97 parts by weight of solvents such
as herein described having dynamic viscosity of 2 to 10 mm /s at 40°C and a flash point in the
range of 70 to 170°C; (b) 1 to 10 parts by weight of high viscosity mineral oils and/or synthetic oils
such as herein described having dynamic viscosity of 100 mm2/s or higher at 40°C; (c) 15 parts by
weight or less of a silicone oil having dynamic viscosity of 150 mm2/s or higher at 40°C; and (d) 1
to 5 parts by weight of additives such as herein described having a lubricating function,'
characterized in that the flash point of the oil type release agent is in the range of 70 to 170°C, and .
dynamic viscosity of the agent is 2 to 30 mm /s at 40°C.
2. The oil type release agent as claimed in claim 1, wherein that the component (a) is contained in a ratio of 70 to 97 parts by weight in total by adding high viscosity mineral oils and/or synthetic oils.
3. The oil type release agent as claimed in claim 1 or 2 as and when used in a spray, wherein the spray amount to a die is 20 cc or less per one shot on the basis of undiluted liquid of the agent.
4. The oil type release agent as claimed in claim 1, further containing a wettability improving additive, preferably 0.1 to 3 parts by weight of an acrylic copolymer or an acryl-modified polysiloxane at the flash point of 100°C or lower.
6. The oil type release agent as claimed in claim 1, further containing antioxidants, preferably 0.2 to 2 parts by weight of one or more said antioxidants selected from the group consisting of amine type, phenol type, and cresol.
8. The oil type release agent as claimed in claim 1, wherein the silicone oil is alkyl silicone oil having alkyl-aralkyl or alkyl groups having longer chain than dimethyl.

Documents:

1382-DELNP-2007-Abstract-(12-04-2012).pdf

1382-delnp-2007-Abstract-(13-07-2011).pdf

1382-delnp-2007-abstract.pdf

1382-delnp-2007-assignment.pdf

1382-DELNP-2007-Claims-(12-04-2012).pdf

1382-delnp-2007-Claims-(13-07-2011).pdf

1382-delnp-2007-claims.pdf

1382-DELNP-2007-Correspondence Others-(09-03-2012).pdf

1382-DELNP-2007-Correspondence Others-(12-04-2012).pdf

1382-delnp-2007-Correspondence Others-(13-07-2011).pdf

1382-DELNP-2007-Correspondence Others-(14-03-2012).pdf

1382-delnp-2007-correspondence-others 1.pdf

1382-delnp-2007-Correspondence-Others-(18-07-2011).pdf

1382-DELNP-2007-Correspondence-Others-(23-02-2011).pdf

1382-DELNP-2007-Correspondence-Others.pdf

1382-delnp-2007-description (complete).pdf

1382-delnp-2007-Drawings-(13-07-2011).pdf

1382-delnp-2007-drawings.pdf

1382-DELNP-2007-Form-1-(12-04-2012).pdf

1382-delnp-2007-Form-1-(13-07-2011).pdf

1382-delnp-2007-form-1.pdf

1382-delnp-2007-form-18.pdf

1382-DELNP-2007-Form-2-(12-04-2012).pdf

1382-delnp-2007-Form-2-(13-07-2011).pdf

1382-delnp-2007-form-2.pdf

1382-DELNP-2007-Form-3-(23-02-2011).pdf

1382-DELNP-2007-Form-3.pdf

1382-delnp-2007-form-5.pdf

1382-delnp-2007-form-6.pdf

1382-delnp-2007-GPA-(18-07-2011).pdf

1382-delnp-2007-gpa.pdf

1382-delnp-2007-pct-210.pdf

1382-DELNP-2007-PCT-237.pdf

1382-DELNP-2007-PCT-304.pdf

1382-delnp-2007-pct-311.pdf

1382-delnp-2007-pct-338.pdf

1382-delnp-2007-pct-373.pdf

1382-DELNP-2007-Petition-137-(14-03-2012).pdf


« Previous Patent
Next Patent »
Patent Number 253270
Indian Patent Application Number 1382/DELNP/2007
PG Journal Number 28/2012
Publication Date 13-Jul-2012
Grant Date 10-Jul-2012
Date of Filing 20-Feb-2007
Name of Patentee AOKI SCIENCE INSTITUTE CO., LTD.,
Applicant Address 4-2-8, ROPPONGI, MINATO-KU, TOKYO, 106-0032 JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 AOKI HISAHARU C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
2 TOGAWA KOJI C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
3 OHIRA HIROBUMI C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
4 KOBAYASHI MASANAO C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
5 YAMAZAKI YUICHI C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
6 KOMATSUBARA HIROAKI C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
7 SHIMIZU TOSHIAKI C/O AOKI SCIENCE INSTITUTE CO., LTD., OF 4-2-8,ROPPONGI, MINATO-KU,TOKYO, 106-0032 JAPAN
8 HARADA MASAYUKI C/O KOTOBUKI KINZOKU KOGYO CO., LTD., OF 1, KITAYAMA, HOUKOUJI-CHO, NISHIO-SHI,AICHI,445-0892 JAPAN
9 YOKOI MITSUYOSHI C/O KOTOBUKI KINZOKU KOGYO CO., LTD., OF 1, KITAYAMA, HOUKOUJI-CHO, NISHIO-SHI,AICHI,445-0892 JAPAN
10 IZAWA RYUSUKE C/O RYOBI LIMITED, OF 762, MESAKI-CHO, FUCHU-SHI, HIROSHIMA, 726-8628 JAPAN
11 FURUKAWA HIDEKI C/O KOTOBUKI KINZOKU KOGYO CO., LTD., OF 1, KITAYAMA, HOUKOUJI-CHO, NISHIO-SHI,AICHI,445-0892 JAPAN
12 KITO MASAYUKI C/O AISAN INDUSTRY CO., LTD., OF 1-1-1, KYOWA-CHO, OBU-SHI, AICHI, 474-8588 JAPAN
13 YORIOKA KEIGO C/O AISAN INDUSTRY CO., LTD., OF 1-1-1, KYOWA-CHO, OBU-SHI, AICHI, 474-8588 JAPAN
14 HAYASHI AKIHIRO C/O AISAN INDUSTRY CO., LTD., OF 1-1-1, KYOWA-CHO, OBU-SHI, AICHI, 474-8588 JAPAN
PCT International Classification Number B22C 3/00
PCT International Application Number PCT/JP2005/015737
PCT International Filing date 2005-08-30
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2004-252056 2004-08-31 Japan
2 2005-107556 2005-04-04 Japan
3 2005-157616 2005-05-30 Japan