|Title of Invention||
A BATCH TYPE POLYIMIDE FILM PRODUCING MACHINE
|Abstract||The invention relates to a batch type machine for coating polyimide from polyamic acid more specifically the invention relates to manufacture of polyimide film of the structu re I * The machine comprises a stainless steel drum (1) on which the polyamic acid is spread with the help of a hopper ( 11), the said drum (1) is rotatably mounted on bearings (2), the top half of the said drum (1) is provided with a hinged (10) insulated (6) top cover (5) with a plurality of infra red heating lamp (8) and suction exhaust (7)^ at the bottom corner of the said drum (1) is provided with heater (9) and a cutting unit with a doctor's blade (9) mounted on shafts (4) with the said blade (9) adjustably mounted ( 10*11) close to the drum (1) and a hopper (11) for resin provided at one side of the said drum (1)*|
This invention relates to a batch type machine for casting polyimide film from polyamic acid. In a specific embodiment this invention relates to the manufacture of polyimide film of the structure I.
Polyimide films are well known for their excellent . dielectric properties and ability to withstand high temperature of 350 C for continuous use* The films of polyamic acid are cast on a surface and the solvent evaporated* Then, in the presence of nitrogen or any inert gas, the temperatu re is raised to imidise the polyamic acid* Polyimide film is extensively used in the form of tapes of 50 to 75 thick,12 mm to 50 mm in width of minimum acceptable length of 50 meters, for electrical insulation of rectangular copper strips*,
The machine for continuous manufacture of polyamide film is
very expensive (, It is an object of the invention to provide
a design of a machine for the preparation of polyimide film in
batch mode which also produces polyimide tapes of different
width and thickness* >
Presently polyimide film is manufactured in a continuous cast i ng mach i ne «.
There are disadvantages associated with the continuous casting machine for the manufacture of polyimide film*
One of the main disadvantages in that the continuous casting machines are expensive and requires high initial invest-ment .
Another disadvantage with the continuous casting machine is that it gives high output requiring higher batch quantity of each size which often may be much higher than the market demand,.
Yet another disadvantage is that the continuous casting machine is very sophisticated requiring high maintenance cost and skilled operators*.
Therefore main object of the present invention is to provide a batch type machine for casting polyimide film which is considerably economical compared to continuous mach i ne b
Another object of the present invention is to provide a machine for the manufacture of polyimide film in batchmode of required thickness which is capable of cutting into tapes of required width and length.
Yet another object of the pre sent invention is to provide a machine for manufacture of polyimide film in batch mode in marketable quality and quantity at a very low cost meeting the users demand in all respect*
According to the present invention there is provided S batch type machine for casting polyimide film compr i s i ng a stainless steel drum on which the polyamic acid is spread with the help of a hopper, the said drum is rotatably mounted on bearings, the top half of the said drum is provided with a hinged insulated top cover with a plurality of infra red heating I amp and suction- exhau s tf at the bottom corner of the said drum
is provided with heater and a cutting unit with a doctor's blade mounted on shafts with the said blade adjustably mounted close to the drum and a hopper for resin provided at one side of the said drum*.
The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to noh-I im i t i ng exempiary embod iments of the invention represented in the accompanying drawing ,.
Fig*, 1 shows the front view of the machine for casting poly imide film.
F i g v 2 shows the sectional side view of the machine*
Fig ► 3 shows the arrangement of the Doctor's blade.
F i g fc 4 a.'Shows the cutting unit with the mounting arrangement of the blade, and F i g „ 4b shows side view of Fig.. Ua .,
Figs,. 1 and 2 shows the genera I arrangement of the mach i ne *, The drum made of stainless steel in rotatably
mounted on two bearings (2) at two sides* A gear for the drive system (3) is shown which is connected to a motor (not shown) „
There is a top cover (5) which is insulated (6) with glass wool i. The top cover (5) is hinged (10) at one end multiple pipe (7) for exhaust alongwith infra red (8) heat lamps are provided at the top of the cover (5). Heater (9) are provided at the right hand bottom corners*.
A hopper ( 11) for resin is adjustably mounted at one s ide of the drum,
A pair of shaft (4) at the middle portion of the drum (1) holds the cutting unit (Figs,. 3 and 4) *
The doctor's blade (9) of width same as the length* of the drum (1) is mounted adjustably ( 11,19) on a blade holder
(12) with two guide rods ( 13). The cutting unit is mounted
on two shafts.(4). The cutting unit guide ( 14) with guide rod
(13) and screw ( 14) is mounted on a cutting unit bracket (17)
provided with a wear piece ( 15). The unit is provided with
a cut strip guide roller ( 16). A take up spool ( 18) is provided near the cutting unit.
Fig. 3 shows the detail of Doctor's blade (9) arrangement which is adjustable with a file screw ( 11) against a holding tension of the spring (19). The blade holder is mounted on guide shaft (4) with a linear bearing (20).
Polyimide film casting technology involves the cure temperature of 250 C to 300 C for more than 30 minutes, in an insert a tmosphere >>
In accordance with the present invention manufacture
In structure I > Ar is any aromatic group such as (Q) -} (oYp) e*
and Ar1 is also an aromatic group including ^Q/~°~xSJ/ '
The machine is capable of producing polyimide film in the batch mode of required thickness* and subsequently capable of cutting it into tapes of requ i red width ♦,
The machine uses intrared lamps., electric heating coils
or any indirect method of heating*,
The entire assembly is arranged in an enclosure having removable lid. Provision of circulating dry nitrogen in the
unit is made to provide inert atmosphere* A stripmatter is prov ided wh i ch moves parallel to the surface from one end to the other and the speed of the movement of the cutter is controlled as per the requi rement>. Wh ile drum is rotating a very sIow rpm, the cutter moves across the drum at controlled speed, giving the desired width of the tape» By varying the speed of the cutter, keeping the r»pjru of the drum constant 4", 2" > 1 " and 1/2" or desired width tapes
can be obtained of 50 m length and above.
The machine comprises a stainless steel drum (1) of diameter 1 m and length 1 „5 m on wh ich the polyamic acid is spread with the help of a hopper ( 11) or by hand or spray „ The drum rotates at predet ermined speed (revolu-tions per minute - rpm) along a horizontal ax is and is driven without any jerks with the help of a variable speed direct current motor. The rpm is maintained such that the resin spreads uniformly on the drum without spilling
out or forming lumps*. Typically, the rpm is maintained he two on 1 to 5 * F i gu re 2 shows the sectional side view of I he innch i no
and the hopper *,
The thickness of the polyamic acid is mainntained at
required level with the help of a blade (9) having the width equal to the length of the drum* Figure 3 shows the details of the doctor's blade arrangement*. The distance between the drum (1) and the doctor's blade (9) is adjusted according to the thickness of film requ i red and the solid co-n tent of the polyamic acid. The distance between the doctor's blade (9) and the drum (1) is adjusted with the help of the screws (11) and spring (19) as shown*, The doctor's blade (9) is finely machined in order to maintain the gap from the drum uniform* The solvent is evaporated from the drum by switching on the i nfrared I amp (8) ^ The tempera ture is maintained at about 150 to 200 C „ The solvent evaporates leaving behind the residue,. The drum (1) is kept rotating during the solvent evapora-tion also. The vapours are sucked away (7) from the machine by connecting it to an exhaust fan ( not shown),. The provision for such an arrangement is shown in Figure 1, the front view of the machine*. Nitrogen or any inert gas is passed into the chamber containing the drum,. Heaters (9) are switched on to heat the drum to higher tempera tures*. The gas is continuously purged into the chamber.. The film cast on the drum is fully imidised by continuous heating for prolonged period of time*.
After the imidisation is complete, the film is cut into tape of required width* The tape is then rolled onto a take
up spool (18), The cutting arrangement is shown in Figure 4.
2 Since the film cast on the drum has the area of 4*71m >, the
I eng th of the tape depends on the width of the tape cut.That
for a width of 1 cm, a tape of 471 m can be obtained. Similar
for a width of 1,5 cm, a tape of 314 m can be obtained,* and
so on .
The i nvent ion described herei nabove is in relation to
a non-limiting embodiment and as defined by the accompanying
cI a ims fc
1. A batch-type polyamide film producing machine comprising:
- a hopper (11) having polyamic acid stored therein?
- a stainless steel drum (1) disposed in a chamber being uniformly rotatable along a horizontal axis by means of a variable speed direct current motor, the hopper
2« The machine as claimed in claim 1 wherein the drum is mounted on atleast two bearings f and wherein the drum CI) is rotated via a gear (3) by the motor-
3* The machine as claimed in claim 1 wherein the chamber has a top cover (5) afixed via a hinge (6) at one end? and wherein a multiple pipe for exhaust of the vapour generated from heating of the solvent being disposed on the top cover (5) the cover (5) being insulated by glass wool (6)
4. The machine as claimed in claim 1 wherein the doctor's
blade (?') is adjustably mounted on a blade holder (12) supported
by a pair of shaft (4)» the shaft being disposed on the drum
(i)i and wherein a bracket (17) accomodating a guide (14) with a
guide rod (13) and a screw the blade (9)•
5. The machine as claimed in claim 4 wherein the bracket (17)
is provided with a wear piece (15)? and wherein a cut strip
guide roller (16) is adjustably disposed to enable the blade
(9) to cut the film into tape of desired length, the tape is
being rolled onto a take-up spool (18).
6- A batch type machine for casting polyimide film as hereinabove described and illustrated*
|Indian Patent Application Number||1573/MAS/1997|
|PG Journal Number||27/2007|
|Date of Filing||14-Jul-1997|
|Name of Patentee||K.VIJAYA CHANDRA RAO|
|Applicant Address||A.B.R.ORGANICS LIMITED, A-3,MADHAVA APARTMENT, HYDERABAD-500 013.|
|PCT International Classification Number||B29D-7/01|
|PCT International Application Number||N/A|
|PCT International Filing date|