Title of Invention

"BLOWING AGENT POWDER AND PROCESS FOR PRODUCING THE SAME"

Abstract A powder comprising a blowing agant powder core which is coated with at least one oil-like substance on its surface and a process for producing a powder comprising  a  blowing  agents  powder  core  which   is  coated with at least one oil-like substance on its surface, comprising the following steps (a) and (b) : (a) adding at least one oil-like substance in the form of a mist to a blowing agent powder; and (b) mixing the oil-like substance with the blowing agent powder under such mixing conditions that the blowing agent powder is less susceptible to pulverization.
Full Text The present relates to a blowing agent powder and a process for producing the same.
2. Discussion of the Background
Blowing agents have conventionally been used in the form of a fine powder, and have posed a problem of dusting in the working atmosphere.
As a means for eliminating the above problem, a technics has been proposed in which a blowing agent powder is mixed with a wax under heating using a mixer having shearing blades, mixing blade*, or the like, and the rasultant mixture is granulated (see Japanese Published Unexamined Pntent Application No,, 90543/77) . How«ve::, the granulated blowing agent obtained by the abovo technique has poor homogeneity and poor disporiaibility into resins. It is therefore difficult to use the granulated blowing agent to obtain a finely and evenly foamed object, and therefore, the granulated blowinq agent is hence unsatisfactory for practical use.
Furthermore, such conventional blowing agents have a problem that they agglomerate and are solidified
with the lapse of time or under load to thereby show impaired flowability in the step of addition to resins to cause hopper clogging/ or to thereby have impaired disperaibility into resins. Mitigation of this solidification is desircid more and more with the recent trend toward quality improvement in foamed resins and labor saving in the production thereof.
On thci other hand, techniques which have been employed for inhibiting the solidification of blowing agents include (1) technique of adding inorganic powder particles, e.g., silica, metal silicate or the like, as a soladification inhibitor to A blowing »gent, (2) technique of batchwise drying a blowing agent for a sufficient period to thereby diminish the water contained therein in a However, use of these techniques has various
drawbacks. Namely, technique (1)/ although effective in solidification prevention in some degree, cannot impart the eff ect which lasts beyond several months. For application to a blowing agent comprising finer particles, inorganic povrder particles should be added in a larger amount. However, the addition of a larger amount of the inorganic powder particles is causative of cell anlargement during foaming, and is hence undesirable in applications where fine cells are required. Technique (2), on the other hand, has
significantly reduced productivity because the drying requixes much time, resulting in an increased production cost. In addition, technique (2) cannot cope with continuous production.
Japanese Published Unexamined Patent Application No. 320432/92 discloses a method of adding a silane coupling agent dissolved in a solvent to azodicarbonainide to thereby improve flowability and dispeEisibility into resins. Furthermore, Japanese Published Unexamined Patent Application No. 295872/96 discloses a. method of adding an aluminum coupling agent dissolved in a solvent to a chemically blowing agent to thereby improve flowability and dispersibility into resins. However, these techniques each is insufficient in the effect of solidification prevention and ineffective in eliminating the problem of dusting.
SUMMARY OF THE INVENTION An object of the present invention is to provide a modified blowing agent powder which is inhibited from causing dusting in the working atmosphere during each of packaging,, transportation, storage, use, and the like, and is inhibited from aggregation and solidification with the lapse of time or under load, is homogeneous, and has satisfactory dispersibility into resins.
Another object of the present invention iff to provide a process for producing the blowing agent powder.
According to the present -invention there is provided a powder comprising a blowing agent powder core which is coated with at least one oil-like substance of the kind such as herein described on its surface
Furthermore, these and other objects of the present invention have been attained by a process for producing a powder comprising a blowing agrent powder core which is coated with at least one oil-like substance on its surface, comprising the following steps (a) and (b):
(a) adding at least one oil-like substance in the
form of a mist to a blowing agent powder; and
(b) mixing the oil-like substance with the
blowing agent powder under such mixing conditions that
the blowing agent powder is less susceptible to
pulverization.
DETAILED DESCRIPTION' OF THE INVENTION The present inventors ma do intensive studies in order to accomplish the above problems. Afl a result, the inventors have found that a blowing agent powder having the desired properties is obtained by adding an oil-like substance in the form of a mist to a blowing agent powder and mixing the oil-like substance with the
blowing agent powder under such mixing conditions! that
the blowing agent powder is less susceptible, to
pulverisation. As a result,, dusting in the working
atmosphere is inhibited during each of packaging,
transportation, storage, use, and the like, and a
blowing- agent powder which is homogeneous and has
satisfactory dispersibility into resins is provided.
Furthermore, the present inventors assumed that
the solidification of a blowing agent powder proceeds
becmisot a slight amount of water, specifically the water
contained in a slight, amount in the blowing agent
©articles and the water absorbed by the blowing agent particles from the atmosphere during production,
transportation, and storage, serves to bond the blowing
agent particles to one another on their surfaces.
Further investigations were made based on this assumption. As a result, the present inventors: nave
found that a blowing agent powder significantly
inhibited from solidification and satisfactory in
flowabUlity, dispersibility into resins, and the like,
even after the lapse of a prolonged period of time is
obtained by reacting the water contained in blowing
agent particles with a surfaott-treating agent capable of
removing wat«sr from l:he blowing agent, such as a
couplirig agent, and preferably form a film of the
surfaca-treating agent on the surface of the blowing
agent particlas. As A result, solidification of the blowing agent: powder is markedly inhibited, and a. blowing agent powder which is homogeneous and has satisfactory dispersibility into resins is provided.
The blowing agent: powdetr which can be Msed in the present invention is selected from conventionally known blowing agents. Examples include blowing agents, for examples, azodicarbonamide (APCA) , hydraatodiearbonamide (HDCA) , p,p'-oxybisj (benzenesuifonyl hydrazi.de) (OBSB), dinitropent&cne thylean,etetramine (DPT) , p-toluenesulfonyl hydrazid* (TSH), benzenesulfonyl hydraaide (BSH) , 5-phen^ltetrazole (5-FT), and the like, and salts of these 1*2. th an alkaline earth metal (e.g., calcium, barium, or strontium) or with aluminum, and the like; and inorganic blowing agents, for example, sodium hydrogen carbonate, anhydrous monosodium citrate, and the like. Among these, preferred are AECA, OBSH,, DPT, TSH, B£>H, 5-PT, and the like; and salts of theses with calciurr, barium, strontium, aluminum, and the like. Especially preferred is ADCA.
in the present invention, these blowing agent powdecs are used alone or as a mixture of two or more thereof.
Although the particle diameter of the blowing agent powder is not particularly limited in the present invention, the process of the present invention is

generally applicable to blowing agent powders having a particle diameter of about 1 to 100 uzn, which often pose the problem of dusting. The particle diameter of the blowing agent powder is preferably about 2 to 50 urn, more preferably about 3 to 30 urn, and most preferably about 3 to 20 urn. The term 'particle diameter" as used herein for a blowing agent powder means the median size thereof determined with a laser diffraction type particle size distribution analyzer.
The blowing agent powder for use in the present invention may contain one or more other ingredients known in this field, such as a stabilizer, a pigment/filler, a blowing inhibitor, and the like. A blowing agent powder containing these ingredients is included in the blowing agent powder of the present invention.
Examples of the stabilizer include tribasic lead sulfate, dibasic phosphite3, lead stearate, zinc stearate, zinc carbonate, zinc oxide, barium stearate, aluminum stearate, calcium stearate, dibutyltin maleate, urea, and the like. Examples of the pigment/filler include chrome yellow, carbon black, titanium dioxide/ calcium carbonate, and the like. Examples of the blowing inhibitor include maleic acid and the like.
The term "substantially anhydrous" a a used herein means to have a water content lower than 0.03$ by weight,
preferably lower than 0.01% by weight. The water content (% by weight) in a blowing agent (e.g., crystalline ADCA) is herein determined by heating the blowing agent at 110°C for 2 hours while passing water-free nitrogen gas therethrough, introducing the effluent nitrogen gas into a Karl Fisher's water meter (trade name; MKS-1; manufactured by Kyoto Electronics Manufacturing Co., Ltd.) prevented from suffering- water penetration thereinto from th«i surrounding air to measure the .amount, of water contained in the nitrogen gas, atnd converting this water amount into a percentage amount based on the weight of the blowing agent.
Such a substantially anhydrous blowing agent powdez can be obtained by a stop (c) of adding to a blowing agent a surface-treating agent capable of removing water from the blowing agent. The step (c) may be included in the steps relating to the process for producing the blowing agent according to the present invent.ion.
In the process for producing the blowing agent of the present invention including the step (c} , the step may bo carried out prior to, during or aftcsr the step (a) . That is, in the process, of the present invention, the oirdor of adding the surf ace-treating agent: and the oil-like substance is not particularly limited/ however, any of: the following methods may be employed: (1) a
method in which -the surface- treating agent is added first,, and an oil-like substance is then added; (2) a method in which the surface-treating agent and aiv oillike substance are added simultaneously; and (3) a method in which an oil-like substance is added first and the surface-treating agent is then added, Among these, method (1) or (2) is preferred in the present invention. More preferably, the surface "treating agent is added to the blowing agent powder - in the form of a mist. According to the addition of the surface-creating agent, the desired blowing agent powder which is inhibited from causing dusting and is inhibited from aggregation and solidification with the lapse of time or under load can be provided.
The sairface-treating agent which can be used in the present invention is one capable of retmoving water from a blowing agent. Examples include compounds having the property of chemically reacting with water and compounds having the property of adsorbing or holding water. Specific examples include coupling agents, organic acid anhydrides; anhydrous inorganic compounds, desiccants,, and the like.
.Examples of the coupling agents include siilane coupling agents, aluminum coupling agents, titanate coupling agents, and the like.
Examples of the silane coupling agents include conventionally known silane coupling agents. Specific examplns include methyltrimethoxysilane, -aminopropyl-
triethoxyailane, N- {ß-aminoethyl) -~ai!ninoPropyl-trimethoxyailane, N-phenylaminometehyltrimathoxysilane, vinylmethyldiethoxysilane, and the like.
Examples of the aluminum coupling agents include conventionally known aluminum coupling agents. Specific examples include aluminum isopropylate, aluminum ethylate, aluminum trim(ethylacetoacetate), othylaceto-acetolualuminum dii sop ropy late, and the like.
Examples of the titanate coupling agents include conventionally known titanate coupling agents. Specific examples include isopropyl triisostearoyl titanate, isopro;pyl tris {dioctyl pyrophosphate) titanate, tetrao::tyl bis{ditrideeyl phosphite) titanate, bis(dioctyl pyrophosphate) hydroxyacetate titanate, and the like.
These coupling agents can be used alone or as a
aijftuns off two or more thereof. Amonn thasa. nrafarrod are aluminum coupling agents, particularly, aluminum
triu(ethylaeetoaeetate).
It is considered that the aluminum coupling agent
reacts with water contaxned in a blowing agent powder by
mixing with the blowing agent powder to form a film of
aluminuuB. hydaroxido on the surface of the blowing agent
particles, A substantially anhydrous blowing agent can be produced according to such effect that the aluminum coupling agent remove the water present on the surface and in the pores of the blowing agent powder. Furthermore, even i£ a quite small amount of water is remained in the inner parts of the blowing agent powder, the film composed of aluminum hydroxide keeps the surfaos of the powdnsr substantially anhydrous by shielding the transfer- of the water to the powder surface to thereby contribute to aggregation and sol.idification prevention.
Additionally, the aluminum coupling agent remaining unreacted is considered to inhibit hygrrosssopicity from the external to thereby contribute to prevention of aggregation and solidification due to its wabar repollency.
Examples of the organic acid anhydrides include
conventionally known, organic acid anhydrides. Specific examples include phthalic anhydride, succinic anhydride, glutarric anhydride, benzoic: anhydride, trimellitic anhydri.de, and the like. These compounds react with and remove water in a blowing agent, for example/ by the following Kvachanis.cn:
(RCO)20 + H20 -* 2RCOOB (wherein R represents an organic atcid residue) .
The above coupling agents and the organic acid anhydrides can be especially preferred because they not only have the property of chemically bonding to water to thereby remove the water contained in a blowing agent, but alEto have the property of forming a film capable of preventing external water absorption on the surface of the blowing agent (for example, unreacted coupling agent, and thot like) .
Examples of the anhydrous inorganic compounds include known anhydrous inorganic compounds BO long as they can remove crystal water by binding to water. Specific examples include anhydrous magnesium sulfate, anhydrous potassium carbonate, anhydrous sodium carbonate, anhydrous sodium sulfate, anhydrous sodium suli?lt«., anhydrous magnesium carbonate, and the like. Theiie compounds reacts with water contained in a blowing agent and fix the reacted water as crystal water, for example,, by the following typical mechanism:
NaaS04 4- nH20 -+ Na2304"nH2O (whtkre.m n represents an integer of 1 or more) .
Examples of deiuiccants include conventionally knovrn desiccants so long as they have the property of removing water. Specific examples include acid clay, silica gel, magnesium oatide, calcium oxide, and the like.
In the present invention, the coupling agents, the organic *cid anhydrides, the anhydrous inorganic
compounds, and the desiccants may be used alone or as a
mixture of two or more thereof as the surface-treating
agent.
The addition amount of the surface-treating agent based on the blowing agent powder is preferably selected
so that the surface-treeting agent amount is sufficient to permit the water contained in the blowing agent powder to react completely. Specifically/ the surface-treating agent can be used in an amount of about 0.01 to 10 pasts by weight; preferably about 0.05 to 0.5 parts by weight, based on 100 parts by weight of the blowing age;at powder.
Upon application to the surface of a blowing agent and preferably heating, the surface-treating agent efficiently reacts with water contained in the blowing agent to thoroby reduce the waiter content of the blowing agent.
The surface-treating agent is preferably used as it is without being dissolved in a solvent/ preferably under conditions substantially free of a solvent, in ordoir that no adverse influence be exerted on reaction with water 02* adsorption of water. If a solution or diaper.rion of an coupling agent in a solvent is used, the reaction between the water present in the blowing agent and the coupling agent does not proceed sufficiently, water is remained in the blowing agent.
and tharefoere a substantially anhydrous blowing agent cannot oe containted. consequently such use is NOT
preferred. Especially, use of an organic solvent
containing water or moisture is not preferred because a
water content in the blowing agent may be increased to
the contrary.
The term "under conditions substantially free of
water1' as used herein means that no solvent is used or that, an oxganic solvent containing a water content of less than 0,1% by weight is used in an amount equal to or lesis than the amount of the surface-treating agent. In the case of using a solid surface-treating agent/ it is preferably used in the form of a fine powdar or, after being melted.
:in the case of using a surface-treating agent which is solid at ordinary temperature, the surface-treating agent is preferably subjected to preheating treatment prior to the addition thereof to a blowing agent. For example preferably, the solid aluminum coupling agent is subjected to heating treaitment at 70 to SC°C so that the heated and melted alumimtm coupling agent is used.
The term "oil-like substance" as used herein means any of oils and fats in a liquid to solid state, hydrocaebons, and fatty acids.

Examples of the oils and fats include natural fat* darived from vegetables or animals, such as soybean oil, coconut oil, linseed oil,, cotton seed oil, rape seed oil, tung oil, pine oil, rosin, castor oil, baef tallow, squalarte, lanolin, and hardened oils, and purified products of these.
Examples of the hydrocarbons include aliphatic hydrocarbons having 20 to 48 carbon atoms, inclusively called paraffin wax«is, and derivatives thereof; aliphatic hydrocarbons having 8 to 19 carbon atoms and derivatives thereof (for example, dialkyl phthalates (e.g., dioctyl phthalate, and the like), phthalates of higher alcohols (e.g., nonyl phthalate, and the like), and the like) ; parafi?inic, naphthenic, or aromatic processing oils; liquid paraffins; and the like. The above hydrocarbons include those isolated and purified from the abovo natural oils and f ats.
Examples of the fatty acids include fatty acids (for example, laurie acid, myristio acid, palmitic acid, stearice acid- oleic acid, behenic acid, and the like) , salts thezreof, and other derivatives thereof. The fatty acids include those isolated »nd purified from the above natural oils and fats.
Oil-like substances having a melting point of 90°C or lower are preferably used in the present invention. More preferred are oil-like substances which
are liquid at ordinary temperature. An especially preferred oil-like substance is a liquid paraffin.
In the> present invention, the oil-like substance can ha used as it is or after being diamolved in an appropriate solvent. Examples of the solvent include aromatic hydrocarbons, such as toluene, xylene and the like. In the case where an oil-like substance which is solid at ordinary temperature is used, it id preferred to liquefy the same by heating.
In the step (a) in the present invention, the addition of an oil-like substance to a blowing agent powder is accomplished by forming a mist of the oil-like subsbance and spraying the some over the blowing agent powder. If an oil-like substance placed in a container/ e.g., (i cup, is directly added to a blowing agent powder, for example, by dropping, the blowing agent powder cannot be sufficiently mixed with the oil-like substance. As a result, blowing agent powders which, even in the sartus lot, hav Examples of methods for forming a mist of an oil-lik« substance and spraying the mist over a blowing agent powder include a method in which a liquid oil-like subnta-'ice or an oil-like substance which has been
liquefied by heating is sprayed over a blowing agent ponaer oy means ox on acomner, ttxainpj.es or cne
atomizer include a two-fluid nozzle and a pressure noszl*. The size of the mist particles during spraying is generally about 0.1 to 100 (in,, preferably about 1 to 50 jim, and more preferably about 1 to 10 (Jm.
The addition amount of the oil-like substance based on the blowing agent powder is preferably 0.001 to 10 parts by weight, more preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of the blowing agent powder. By regulating the addition amount of the oil-like substance to 0.001 part by weight or more, a blowing agent powder sufficiently inhibited from causing dusting can be obtained. By regulating the addition amount of the oil-like substance to 10 parta by weight or leu a, preferably 0.5 part by weight or lean, the blowing agent powder can be inhibited from solidification or having impaired diapersibility into resins.. More specifically, it is preferred to regulate the addition, amount of the oil-like substance according to the specific surface area of the blowing agent powder. For eixample, the addition amount of an oil-like substance for a blowing agent powder having a small specific surface area (0.1 to 2 m2/g) is preferably small (0.001 to 0.5 part by weight), while that for a blowing agent powder having a large specific surface
ares (2: to 10 ra2/g) is preferably large (0.2 to 10 parts by weight).
In the step (b) in the present invention, the mixing' is conducted under mixing conditions that the blowing agent powder is less susceptible to pulverization. Herein the term "under mixing conditions that the blowing agent powder is less susceptible to "pulverization" means that an increase in the specific surface area through the mixing is ^20% or less, I more preferably 10% or less. Mixing apparatuses which can be used for the above mixing ar«> not particularly limited. Examples include supaiiaixers, Henschel mixers, screw mixture such as mnaturs mixtuers procheer mixter and ribbon
blenders.
If a blowing agent is pulverized in the above mixing, dust reducing effect may be lost, and the resultant powder has an increased specific surface area and honce enhanced hygroscopicity. Additionally, even if t.h« blowing agent powder which has been coated to inhibit water adsorption is used, a section having no coabing is provided, and hence hygroscopicity is enhanced move and more. Thus, the effect of the present invention may be lost. Particularly, if the blowing age.at powders having a particle diameter of 10 pun or mona which are easily pulverized are used, it should be especially paid attention to this point.
For more evenly mixing a blowing agent powder
with an oil-like substance in the present invention, the
mixing apparatus used is preferably operated at a
sufficiently high mixing speed as long as the blowing
agent powder is inhibited from being pulverized. Namely,
it is preferred to conduct the mixing under such
conditions that the blowing agent powder is not
pulverized, in such a manner that the blowing agent
powder is evenly sprayed with the oil-like substance, in
oth«-.r words, the blowing agent powder is sprayed with
these- .ingredients over a certain period so as to avoid
unevenness of spraying.
in the step \nj in tne prasent. invention, cue
blowing agent powder is mixed with the oil-like
substance and the like under heating.
For example, the heating temperature i» generally
froir :tOeC to the decomposition temperature of the
blowing agent, preferably from 4 0CC to the decomposition
tempersture of the blowing agent, If ADC A, OBSH, DPT or
the like having a decomposition temperature of not lower
than l&Q'C is used as a blowing agent, the preferred
temperature ±3 55 to 100°C. From the standpoint of
reducing the heating period to conduct the mixing even
more e-ficiently to thereby minimize the energy cost, it
is preferred to use a heating temperature of about 70 to
90°C.
The addition method, mixing conditional, and heating temperature in the above method of treating the blowing agent powder with the oil-like substance can be selected in, the same manner at* in the method of treating the blowing agent powder with the surface-treating agent in step (c) .
Although the step (b) m&y be conducted after the step (a) in the process of the present invention, it is especially preferred to simultaneously conduct the steps (a) and (b) . Furthermore, it is preferred that the step (c) is simultaneously conducted.
More specifically, in the case where a. cone ribbon blending dryer having a capacity of 50 liters (trad* name: Ribocone £1 RMS*-50; manufactured by Okawara Mfg. Co,, Ltd.), for example, is used as the mixing appiirabus, it. is preferably operated at u rotational speed of 40 to 100 rpra, a spraying rate for the aluminum compound coupling agent of 1 to 2 00 g/min (preferably 1 to ',10 g/min) , a spraying rate for the oil-like substance of 1 :,o 200 g/min (preferably 1 to 20 g/min) , and a mix.MIg period of 1 to 30 minutes . In the ca.se where a cone ribbon blending dryer having a capacity of 400 liters (trade name: Ribocone IB RME-400; manufactured by Okawaru Mfg. Co., Ltd.), rfor example, is used us the mixing apparatus, it is prefaraily operated under the conditions of a rotational speed of 30 to 70 rpm, a
spraying rate for the aluminum compound coupling agent of 10 to 2,000 g/min {preferably 10 to 100 g/num) , a spraying rate for the oil-like substance of 10 to 2,000 g/min ([preferably 10 to 100 g/min) , and a mixing period of IL to 30 minutes.
Since the blowing agent powder modified by the process of the present invention is inhibited from causing dusting in the handling atmosphere in each of packaging, storage, transportation, use, and the like, it clous not adversely influence the health of the workmen. The blowing agent powder of the present invention is equal or superior to conventional blowing agent powders in foaming performance. Furthermore, since the blowing agent powder of the present invention has satisfactory di*prsibility into resins, it is especially mil table* for use in applications where even and f.Mie forming is required, for examplo, in the production of foamed sheets for use as wall papers. Additionally, since the blowing agent powder of the present. invention ha.si intact unsusceptibility to solidification, it dows not necessitate «i step of pulverisation or the like before use.
The blowing agent powdor of the presenl: invention has loeesi significantly improved especially in unsusceptibility to solidification under load and in unsusceptibility to sollidification with the lapse of
time. Hence, it is not only .hardly solidified even
through long-term storage in a stacked state*, but also
retain* over long the satisfactory flow ability and the
satisfactory dispersibility into resins which properties
are possessed immediately after production.
Consequently, as a result that the blowing agent
powder of the present invention is provided, the fear
that blowing agent powder products may be solidified under load or with the lapse of time from the production
thereof to the use thereof by users is eliminated.
The present invention will be explained below in more detail by reference to Examples, Comparative Examplas, and Test Examples.
The oil-like substances used in the following Examples and Comparative Example* are as follows: Oil-like substance A: highly purified liquid paraffin having 21 carbon atoms on the avwrag© (trade name: U-6; manufactured by Matsumuira Oil Research Corp.); Oil-Like substance B: liquid paraffin having 21 carbon atom* on ths average (trade name, F-60: manufactured by Matsumura Oil Research Corp.);
Oil-like substance C: liquid paraffin having 33 carbon atom* on the average (trade name: P-350P; manufactured by MAtsumura Oil Research Corp.)
EXAMPLES 1 TO 8 Into a con* ribbon blender having a capacity of 50 liters (trade name: Rib o con* E; manufactured by Okawara Mfg. Co. , Ltd.) was introduced 20 kg of ADCA (manufactured by Otsuka Chemical Co., Ltd.; average particle diameter: 5 um; specific surface area: 1.5 m3/g; the same applies in the following Examples 9 to 11 and Comparative Example 1) . Oil-like substance A, B, or C was up rayed over the ADCA with a two-fluid nozzle or a pressure nozzle under the conditions shown in Table 1 given later, while mixing the contents at a rotational spe«d of 76 .rpm. In Table 1, "flow rate" means "flow rate for spratying". After completion of the spraying, the contents were further stirred continuously for 7 minuted and 30 seconds to obtain a blowing agent powder according to the present invention.
EXAMPLE 9
ADCA. was introduced into a supermixer (capacity:
200 liters; manufactured by Kawata Seisakusho K.K.).
Oil--li>.e substance A WJHS sprayed over the ADCA with a
two-fluLd nozzle while mixing the contents at a totation speed or 500 rpm. rearwr, the convenes
were further stirred continuously for 7 minutes und 30 seconds to obtain a blowing agent powder.
EXAMPLE 10 A blowing agent powder was obtained in the same manner as in Example 9, except that the addition of oil-like substance A was conducted by dropping.
EXAMPLE 11 A bloving agent powder was obtained in that same manner as in Example 1, except that the addition of oillike substation A was conducted by dropping.
COMFAIIATXVE EXAMPLE 1 ADCA in the untreated state was taken as a blowing agent powder of Compax'ative Example 1.
TEST EXAMPLE 1 A 5 g portion was taken from the blowing agent powder obtained in each of the above Examples and Comparative Examples, and examined with a Heubach dust motor lior th« degree of dusting (%) under the conditions of a flow rate of 20 1/min and an examination period of 5 minutes. The results obtained are shown in Table 1.
TABLE 1
(Table Removed)
The results given in Table 1 show that the blowing &g«nt powders according to the present invention were significantly inhibited from causing dusting as
compared with the untreated blowing agent powder (Comparative Example 1) .
TEST EXAMPLE 2
A 400 g portion of each of the blowing agent powder.1: obtained in the above Example 1 and Comparative Example 1 wa;3 packed into a polyethylene bag having dimensions of 23 cm by 13 can. After sufficient deaeation, the opening of- each bag was heat-sealed. The packages thus obtained were stacked, and a load of 0.08 k:r/cm2 was imposed on the aitack. These packages were allowed to stand for 10 days in that: state to obtain blowing agent powders to be tested.
To 100 parts by weight of poly(vinyl chloride)
were added 3 parts by weight of each blowing agent
powder to be tested, 2.5 parts by weight of a
calciurr./zinc. compound stabilizer (trade nane: KV-83;
manufactured by Kyodo Chemical Co., Ltd.), and 60 parts
by weight of a plastieizer (dioctyl phthalate). These
ingredients were mixed by means of a propeller miicer at
400 rpm for 3 or 7 minutes. The resultant mixtura was
applied to a flame-retardant paper for wall paper use in
a thickness of 0.25 mm over em area having a width of 12u mm ana a rongtn or 400 mm, and the coating was
caused to gel by heating at 145°C for 45 seconds to
obtain a ah«et. The sheet obtained was viaually

examined to count the number of blowing agent solidification contained therein to thereby evaluate diapereiibility.
Both samples had the same diaperaibility. The results show that the blowing agent powder of the prosent invention was equal in foaming performance to the untreated blowing agent powder.
EXAMPLE 12 In a cone ribbon blender (trade nane Ribocone E RME-4CQ; manufactured by Okawara Mfg. Co., Ltd.) was placed. 250 kg of ADCA (manufactured by Qtsuka Chemical Co., Ltd. ; average particle diameter, 20 uni; the same applie s in the following Examples 13 to 18 and Comparative Example 2-4} . Thereto were niinultaneously added, with stirring at 70 rprit and 90CC, 250 g of aluminum trii» (ethylacetoacetate) (trade name: ALCH-TR; manufactured by Kawaken Fine Chemicals Co., Ltd.) which had buen molted by heating lit 50°C and 125 g of oil-based substance B which had not been preheated, by spraying in the form of a mis;t using a two-fluid nozzle (the thermally molten aluminum tris (ethylacetoaoetate) was sprayed at a rate of 20 g/min, and the liquid paraffin was sprayed at a rat* of 10 g/min) . After completion of the addition, stirring was further continued under the some conditions for 7.5 minutes to
obtain a blowing agent powder according to the present invent ion.
EXAMPLE 13 In a cone ribbon blender (trade name: Ribocone E RMB-400; manufactured by Okawa.ru Mfg. Co., Ltd.) was placed 250 kg of ADCA. Thereto was added, with stirring at '10 rpn and 90°C, 2150 g of aluminum tria (ethylacetoacetate) (trade name: ALCH-TR; manufactured by Kawaken Fine Chemicals Co., Ltd.) which had b«ten melted by heating ab 90 °C, by spraying in the form of a mist using a two-fluid nozzle (the thermally ttiolt*n al\«n.lnum tris (ethylacetoaeetate) was sprayed at a rate of 20 g/min) . After completion of th« addition, stirring was further continued under the same conditions for 1C> minutes. Subsequently, while the contents were continuously stirred, 125 g o£ oil-based substance B which had not been preheated was added thereto by spraying in the form of a mist using a two-fluid nozzle (the liquid paraffin wais sprayed at a rate of 10 g/min) . Aftfi.r completion of the addition, stirring was further continued for 7.5 minutes to obtain a blowing agent powder according to the present invention.

EXAMPLE 14
In a cone ribbon blender (trade name: Ribocone E RME-400; manufactured by Okawara. Mfg. Co., Ltd.) was placed 250 kg of ADCA. Thereto were simultaneously added, with stirring at 70 rpm and 90°C, 250 g of aluminum tris(ethylacetoacetate) (trade name ALCH-TR; manufactured by Kawaken Fine Chemicals Co., Ltd.) which had be.sm melted by heating a.t 90°C and 125 g of oil-based substance B whi<: had not been preheated by dropping thermally molten aluminum tris was dropped at a rate of g and the liquid paraffin . after completion addition starring further continued under same conditions for minutes to obtain blowing agent powder according present invention.> EXAMPLE 15 A mixture of ,250 g of aluminum tris(ethylaeetoacetate) (trade name: ALCH-TR; manufactured by Kawakon Fine Chemicals Co., Ltd.) and 500 g of oil-baaed aubaitance B was prepared and melted by heating at 90°C beforehand, Subsequently, 250 kg of ADCA was placed in a cone ribbon blender (trade name: Ribocora E RME-400; manufactured by Okawara Mfg., Co., Ltd.). Thereto was added, with stirring at 70 rpax and
90°C/ the aluminum tris (ethylacetoacetate) /liquid paraffin mixture prepared beforehand, by spraying in the form of a mist using a two-fluid nozzle (the aluminum tris(ethylacetoacetate) /liquid paraffin mixture was sprayed at a rate of 20 g/min) . .after completion of the addition, stirring was further continued under the same conditions for 7.5 minutes to obtain a blowing agent powdez according to the present invention.
EXAMPLE 16
In a RME-400; manufactured by Okawara Mfg. Co., Ltd.) was
placed 250 kg of ADCA. Thereto was added, with stirring
at 'W rpm and 90°C, 250 g of aluminum
tris(ethylacetoacetate) (trade* name; ALCH-TR;
had b&en melted by heating at S>0°C, by spraying in the form of a. mist using a presaure nozzle (the thermally molten aluminum tris(ethylacetoacetate) was sprayed at a rata of 40 g/min) . After completion of the addition, stirring was further continued under the same conditions for 10 minutes. Subsequently, while the contents were continuously stirred, 125 g of oil-baaad substance B whish had not been preheated was added thereto by spraying in the form of a mist using a pressure nozzle (tho liquid paraffin was sprayed at a rate of 20 g/min).
After completion of the addition, stirring was further continued for 7.5 minutes to obtain a blowing agent powder according to the present invention.
EXAMPLE 17 In a cone ribbon blender (trade name: Ribocone E RME-400; manufactured by Okawara Mfg. Co., Ltd.) was placed 250 kg of AI)CA. Thereto was added/ Kith stirring at 70 rpia and 90°C, 500 g of aluminum tris (ethylacetoacetate) (trade name: AICH-TR; manufactured by Kawaken Fine Chemicals Co., Ltd.) which had bean malted by heating at 90°C, by spraying in the form of a mi sit using a two-fluid nozzle (the thermally molton aluminum tris(ethylacetoacotate) was sprayed at a rate of 20 g/min). After completion of thfii addition, stirring was further continued under the same conditions for 1C minutes. Subsequently, while the contents were continuously stirred, 125 g of oil-baaed substance B which had not been preheated was added thereto by spraying in the form of a mist using a two-fluid nozzle (the liquid paraffin was sprayed at a rate of 5 g/min) . Afte:c completion of this addition, stirring was further continued for 7.5 minutes to obtain a blowing agent powder according to the present invention.
EXAMPLE 18 In a superraixer (trade name; SMV-200; manufactured by Kawata Seisakusho K.K.) was placed 100 kg of ADCA. Thereto were .simultaneously added, with stirring at 300 rpra and 90°C, 100 g of aluminum tris (ethylacetoacetate) (trade name: ALCH-TR; manufactured by Kawaken Fine Chemicals Co., Ltd.) which had bs;sm melted by heating at 9C°C and 50 g of oil-based subata.nce B'which had not been preheated, by spraying in the form of a mist using a two-fluid nozzle (the thermally wolten aluminum tris(ethylacetoacetate) was sprayed at. a rate of 20 g/min, a.nd the liquid paraffin was sprayed at a rate of 10 g/min). After completion of the addition, stirring was farther continued under the s&nte renditions for 7.5 minutes, to obtain a blowing agent powder,
COMPARATIVE EXAMPLE 2 The untreated blowing agent was taken as a blowing agent powder of Comparative Example 2,
COMPARATIVE EXAMPLE 3
In a cone ribbon blender (trade name: Ribocone E
RME-400; manufactured by Okawara Mfg. Co., Ltd.) was
placed 250 kg of ADCA. Thereto was added, with stirring
at vo rpm and 90°C, 250 g of aluminum
tris(ethylacetoacetate) (trade name: AI.CH-TR; manufaetured by Kawaken Fine Chemicals Co., Ltd.) which had been incited by heating at 90°C as the only additive, by apraying in the form of a mi at using a two-fluid nozzle (the thermally molten aluminum tris (ethylacetoaoetate) was spzrayed at a rate of 20 g/min) . After completion of the addition, stirring was further continued under the same conditions for 7,5 minutess to obtain a blowing agent powder.
COMPARATIVE EXAMPLE 4 In a cone ribbon blender (trade name: Ribocone E RME-400; manufactured by Okawan Mfg. Co., Ltd.) was placed 250 kg of ADCA, Thereto was added, with stirring at 70 rpm and 90°C, 125 g of oil-based substance B which had not been preheated its the only additive, by spraying in th TEST EXAMPLE 3 Evaluation of Solidification Property:
Each of the blowing agent powders obtained in Examples 9 to 14 and Comparative Examples 2 to 4 given
above was subjected to a solidification test in stacking and a solidification test in practical package by the following methods. The results obtained are shown in Table 2.
(1) Solidification Test in Stacking:
Polyethylene bags each having dimensions of 23 cm
by 13 cm were respectively packed with 450 g portions of
a sample. After sufficient deaeration, the opening of
each hag was heat-sealed. The packages thus obtained
were stacked, and a lo«id of 0.216 kg/cm2 was imposed on
the stack. After 14 days, the Hiunple was taken out and
mceaamsei wihh * 14»m»*h sie&G £© t*)«ISM*^. fcrh«- amount of the sample screened out. This amount was converted to %,
which was taken as the value* of solidification in
stacking.
(2) Solidification Test in Practical Package:
A 25 kg portion of a sample was packed into a corrugated fiberboard case for use as a product packaging container for distribion. This package was allowed to stand for 1 month under the conditions of a temperature of 40*C and a humidity of 80%. Thereafter, the sample* was screened with a 14-mesh sieve to measure the amount of the sample screened out. This amount was converted to %, which was taken as the value of solidification in practical package.
Comparative Examples 5 to 8 given above, and examined with A Heubac?h dust meter fox- tho degree of dusting (%) undar the conditions of a flow rate of 20 1/min and an examination period of 5 minutes. The results obtained are also shown in Table 2.
(Table Removed)
*: In the column of Exaxtple 15, 20* is the rate of addition of the aluainuat compouncoupling agent/liquid paraffin mixture.
While the invention has boon described in detail and w:ith reference to specific embodiments thereof, it will be apparent to on«i> skilled in the art, that various changes and modifications can be made therein without departing from the spirit and soope thereof.













We Claim:
1. A process for making a powder comprising a blowing agent
powder core which is coated with one oil-like substance on its
surface, comprising the following steps (a) and (b):
(a) adding one oil-like substance in the form of a mist to a blowing agent powder; and
(b) mixing the oil-like substance with the blowing agent powder by using mixers such as herein described, the oillike substance being used in an amount of 0.001 to 10 parts by weight based on parts by weight of the blowing agent powder at a heating temperature of from 55°C to 100°C such that the blowing agent powder is less susceptible to pulverization.

2. The process as claimed in claim 1, wherein the oil-like substance with the blowing agent powder is mixed under conditions that an increase in the specific surface area through the mixing is 20% or less.
3. The process as claimed in claim 1, wherein the oil-like substance with the blowing agent powder is mixed under such mixing conditions that an increase in the specific surface area through the mixing is 10% or less.
4. The process as claimed in claim 1, wherein the oil-like substance is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the blowing agent powder.
5. The process as claimed in claim 1, wherein the oil-like substance is at least one selected from the group consisting of oils and fats in a liquid to solid state, hydrocarbons and fatty acids.
6. The process as claimed in claim 1, wherein the oil-like substance is a liquid paraffin.
7. The process as claimed in claim 1, wherein the blowing agent powder is azodicarbonamide.
8. The process as claimed in claim 1, having the following step (c):
(c) adding to the blowing agent powder a surface-treating agent capable of removing water from the blowing agent.
9. The process as claimed in claim 8, wherein the surface-treating agent is added in the form of a mist.
10. The process as claimed in claim 9, wherein the step (c) is carried out prior to or during the step (a).
11. The process as claimed in claim 8, wherein the surface-treating agent is one selected from the group consisting of a coupling agerit, an organic acid anhydride, an anhydrous inorganic compound, and a desiccant such as herein described.
12. A process for producing a powder substantially as herein described with reference to the foregoing examples.

Documents:

1991-del-1998-abstract.pdf

1991-del-1998-claims.pdf

1991-DEL-1998-Correspondence-Others-(19-08-2009).pdf

1991-del-1998-correspondence-others.pdf

1991-del-1998-correspondence-po.pdf

1991-del-1998-description (complete).pdf

1991-del-1998-form-1.pdf

1991-del-1998-form-13.pdf

1991-del-1998-form-19.pdf

1991-del-1998-form-2.pdf

1991-DEL-1998-Form-3-(19-08-2009).pdf

1991-del-1998-form-3.pdf

1991-del-1998-form-6.pdf

1991-del-1998-gpa.pdf

1991-del-1998-petition-137.pdf

1991-del-1998-petition-138.pdf


Patent Number 240992
Indian Patent Application Number 1991/DEL/1998
PG Journal Number 25/2010
Publication Date 18-Jun-2010
Grant Date 14-Jun-2010
Date of Filing 10-Jul-1998
Name of Patentee OTSUKA CHEMICAL CO., LTD
Applicant Address 3-2-27, OTE-DORI, CHUO-KU, OSAKA-SHI, OSAKA, JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 TSUKASA MAEKAWA TOSHINORI TAKAO, SADAFUMI SHONO, CHIAKI YASUMARU.
2 SHIGERU SUMITOMO C/O OTSUKA CEMICAL CO., LTD., 463, KAGASUNO, KAWAUCHI-CHO, TOUSHIMA-SHI, TOKUSHIMA, JAPAN.
3 NOBUYUKI UEDA C/O OTSUKA CHEMICAL CO., LTD., 615, AZA HANAMEN, STOURA, SATOURA-CHO, NARUTO-SHI, TOKUSHIMA, JAPAN.
4 YOSHIFUMI TACHI C/O OTSUKA CHEMICAL CO., LTD., 615, AZA HANAMEN, STOURA, SATOURA-CHO, NARUTO-SHI, TOKUSHIMA, JAPAN.
PCT International Classification Number C08K 9/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-69618 1998-03-19 Japan
2 10-107262 1998-04-17 Japan