JPS6412209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyimide film, and more specifically, the present invention relates to a method for producing a polyimide film, and more specifically, fixing the film on a carrier such as a metal drum or an endless belt by means of a means for preventing movement of the film provided on the carrier; The present invention relates to a method for producing a polyimide film characterized by preventing shrinkage movement.

Polyimide films have excellent physical, chemical, and electrical properties over a wide temperature range from low to high temperatures, and therefore have a wide variety of uses. For example, covering electric wires and cables,
It is widely used for coating magnet wires, interlayer insulation in transformers, insulation in flexible printed circuits, etc.

Regarding the manufacturing method of polyimide film, (A) a method of casting a polyamic acid resin solution and then heating it to form a polyimide film, (B) a method of casting a composition consisting of a polyamic acid resin solution, a dehydrating agent, and a catalyst. A typical method is to prepare a polyimide film by heating it after heating. Although method (A) does not require a complicated process, it has the disadvantage of poor productivity because it removes the solvent and converts it to an imide only by heating. On the other hand, method (B) requires a complicated process including mixing with a dehydrating agent and a catalyst, but it is characterized by good productivity because it is easy to remove the solvent and convert it to an imide using a dehydrating agent.
The present invention particularly relates to method (B).

An organic solvent solution of polyamic acid (mixture of polyamic acid resin solution, dehydrating agent, and catalyst) is extruded or cast onto a carrier such as a drum or endless belt using a slit die or coating machine, and a self-supporting film is formed by heating. The self-supporting film (polyamic acid gel film)
generates shrinkage stress due to solvent removal or imidization, and also generates a liquid film formed by the solvent, dehydrating agent, and catalyst between the carrier such as a drum or endless belt and the polyamic acid gel film, and as a result, the liquid film formed on the carrier causes a large contraction. Therefore, the width of the polyamic acid gel film decreases, and even if the polyamic acid gel film is peeled off from the carrier and is attempted to be supported on a film support (for example, a pin sheet) for drying, the width is insufficient and the film cannot be supported. As a way to deal with this,
Methods such as setting it on a support before the shrinkage stress becomes large can be considered, but if the polyamic acid gel film does not have a certain level of strength, the film thickness etc. will be affected and the quality of the film will deteriorate. . Naturally, if the gel film does not have sufficient strength, it will be difficult to break the film or to peel it off from the carrier.

The inventors of the present invention have arrived at the present invention as a result of intensive research into a method for preventing such a reduction in film width on a carrier.

That is, the present invention extrudes or casts an organic solvent solution of polyamic acid, which is a precursor of polyimide, onto a carrier such as a drum or an endless belt using a slit die or a coating machine, forms a self-supporting film by heating, and then applies the solution to the carrier. In a polyimide film production method in which the film is continuously peeled off from the film and then subjected to post-treatment such as dry heat treatment, as a means to prevent the film from moving onto a carrier such as a drum or an endless belt, (a) recesses and/or protrusions provided parallel to the direction of travel;
(b) A rough surface section provided near the end of the carrier in parallel to the direction of travel; and (c) An endless belt provided near both ends of the carrier so as to press the film. Self-supporting properties, either alone or in combination This method of manufacturing a polyimide film is characterized in that both ends of the film are fixed on a carrier to prevent the film from shrinking and moving.

Polyamic acid, which is a precursor of polyimide used in the present invention, is represented by the following structural formula ().

One of the raw materials having this structural formula is an aromatic diamine represented by the structural formula (). Here, R' is a divalent aromatic group selected from a phenylene group, a naphthalene group, a biphenylene group, and a group represented by the structural formula (). Here R ₁ is 1~
alkylene group with 4 carbon atoms, -O-, -S
-, _-SO2- , and groups represented by ().

H ₂ N−R′−NH ₂ () However, R ₂ and R ₃ here are an aliphatic group or an aromatic group. Examples of diamines specifically used in the present invention include metaphenylene diamine, paraphenylene diamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, 4,4'- Diaminodiphenyl sulfide, 4,4'-diaminodiphenylsulfone, 3,
3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 2,6-diaminopyridine, bis(4-aminophenyl)diethylsilane, bis(4-aminophenyl)diphenylsilane, 3,3'-dichlorobenzidine , bis(4-aminophenyl)ethylphosphine oxide, bis(4-aminophenyl)phenylphosphine oxide, bis(4-aminophenyl)-N-phenylamine, bis(4-aminophenyl)-N
-Methylamine, 1,5-diaminonaphthalene,
Examples include 3,3'-dimethyl-4,4'-diaminodiphenyl, 3,3'-dimethoxybenzidine, and mixtures thereof. Among these diamines, particularly preferred are 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane,
4,4'-diaminodiphenyl ether and mixtures thereof.

On the other hand, the other raw material having the structural formula () is an aromatic tetracarboxylic dianhydride.
For example, pyromellitic dianhydride, 2,3,
6,7-naphthalenetetracarboxylic dianhydride,
3,3',4,4'-diphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-diphenyltetracarboxylic acid dianhydride, 2,2-bis(3,4
-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)propane dianhydride, carboxyphenyl)ether dianhydride, naphthalene-1,2,
4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride,
2,2-bis(2,3-dicarboxyphenyl)
Propane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(2,3 -dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, benzene-
1,2,3,4-tetracarboxylic dianhydride,
3,4,3',4'-benzophenonetetracarboxylic dianhydride, etc., particularly preferred are pyromellitic dianhydride, 3,3',4,4',-diphenyltetracarboxylic acid Dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, benzene-1,2,3,4- These are tetracarboxylic dianhydride, 3,4,3',4'-benzophenone tetracarboxylic dianhydride, and mixtures thereof.

Representative examples of the organic solvent used in the present invention include N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These organic solvents can be used alone or in combination with other solvents, or in combination with non-solvents such as benzene, toluene, and xylene. The solid content concentration of the polyamic acid resin solution used in the present invention is 10 to 40% by weight, and the viscosity is 200 to 50,000 poise (B-type viscometer at 20°C), preferably 1,000 to 10,000 poise.
It's poise. The polyamic acid solution used in the present invention also includes a partially imidized polyamic acid resin solution.

Examples of the dehydrating agent used in the present invention include fatty acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, aromatic acid anhydrides such as benzoic anhydride, N,N'-disubstituted carbodiimides, lower Examples include fatty acid halides and mixtures thereof, and at least one acid anhydride selected from aliphatic acid anhydrides and aromatic acid anhydrides is particularly preferred.

Catalysts used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine, isoquinoline, and β-picoline. Although it can be mentioned,
Particularly preferred is at least one amine selected from heterocyclic tertiary amines. Although the mixing ratio of polyamic acid, dehydrating agent, and catalyst is not particularly limited, the effects of the invention are particularly noticeable when the composition falls within the following composition range after coating.

Dehydrating agent/polyamic acid = 1 to 8 (mole ratio) Catalyst/polyamic acid = 0.01 to 1 (mole ratio) To manufacture a polyimide film, first weigh the above polyamic acid resin solution, dehydrating agent, and catalyst in a predetermined amount and add them to a mixer. to obtain a well-mixed polyamic acid organic solvent solution. Next, the solution is supplied to a slit die or coating machine, and extruded or cast coated onto a carrier such as a metal drum or endless belt having a temperature of 50 to 200 °C, preferably 60 to 150 °C by applying a constant pressure. After drying for 15 seconds to 30 minutes to form a self-supporting polyamic acid gel film (partially imidized), it is peeled off from a carrier such as a metal drum or endless belt. In this drying process, the self-supporting polyamic acid gel film tends to be stored in the width direction and the take-off direction on a carrier such as a metal drum or an endless belt due to imidization of the polyamic acid or scattering of the solvent. As for the direction of withdrawal, shrinkage is prevented since the material is forcibly withdrawn in the next step. On the other hand, if a means to prevent shrinkage is not incorporated in the width direction, as the polyamic acid gel film peels off from the carrier, the shrinkage will progress in the width direction.
It becomes difficult to transfer to the next process. The reason why the polyamic acid gel film peels and shrinks more than the carrier is that the solvent accumulates between the polyamic acid gel film and the carrier, this forms a liquid film, and the polyamic acid gel film peels and shrinks more naturally than the carrier. It is estimated that In the present invention, a carrier such as a metal drum or an endless belt is provided with a means for suppressing shrinkage of the polyamic acid gel film in the width direction, so that the polyamic acid gel film can be transferred to the next step with almost no shrinkage. The peeled self-supporting polyamic acid gel film is fixed at both ends with supports such as pin sheets or clips, and heated to 80 to 500℃, preferably 100 to 450℃.
Heat treatment is performed in a drying oven for 1 minute to 1 hour, preferably 3 minutes to 30 minutes. Then 100-400℃, preferably
Post-treatment is carried out at 150 to 350°C for 30 seconds to 1 hour, preferably 1 minute to 30 minutes. After these steps, both ends are slit to obtain a polyimide film.

FIG. 1 shows an example of a manufacturing apparatus according to the present invention. In the figure, 1 is a slit die, 2 is a metal (casting) equipped with means to prevent film shrinkage and movement.
Drum, 3 is a peeling roll, 4 is a chain drive sprocket, 5 is a brush roll, 6 is a peeling roll, 7 is a winding roll, 8 is a pin sheet attachment chain, 9 is a self-supporting film, 1
0 is the product film.

A means for fixing both ends of a self-supporting polyamic acid gel film on a carrier such as a metal drum or an endless belt and preventing shrinkage and movement of the film according to the present invention will be explained based on the drawings. still,
In the following explanation, a metal drum was used as an example, but
It is immediately applicable to endless belts and other cases.

FIG. 2 shows an example in which recesses 12 and/or protrusions 11 are provided near both ends of the metal drum 2 as a means for preventing shrinkage and movement of the polyamic acid gel film. The shrinkage movement of the film due to the anchor effect is remarkable, and the structure is simple.

1 is made up of a metal drum 2 with band-shaped protrusions 11 protruding from the circumferential surface of both ends thereof in parallel to the film traveling direction;
In this example, a plurality of band-shaped convex portions 11 (2
Book) It will be installed protrudingly. 3 has a groove-like recess 12, and 4 has a plurality of (two) groove-like recesses 12 carved therein. 5 is an example in which band-shaped convex portions are provided discontinuously,
That is, a plurality of small protrusions 13 are provided at appropriate intervals to protrude in parallel to the direction in which the film travels. 6
is made by wrapping a shrink Teflon tube 14 around the metal drum 2 except for both ends, and both ends of this Teflon tube 14 or both ends of the drum 2 form the above-mentioned convex or recessed parts, and the application width is wrapped around the Teflon tube 14. By making the width larger than the width of the film, shrinkage and movement of the film can be prevented. Further, due to the releasability of Teflon, the coated polyamic acid organic solvent solution can be easily peeled off, and temperature conditions can be advantageously set. The concave or convex portion is
Although not particularly limited, the width is about 1 to 100 mm, preferably about 5 to 50 mm, the depth (height) is about 0.005 mm to 2 mm,
Preferably, it may be selected appropriately within the range of about 0.01 to 1 mm.

FIG. 3 shows an example in which the vicinity of both ends of the metal drum 2 is roughened (matte finished) in a belt shape. 1 has a band-shaped rough surface part 15 provided on the circumferential surface near both ends of the drum 2, and 2 has a rough surface part 1 provided in a concave part at both ends of the drum 2.
This is an example in which 5 is arranged. The rough surface portion can also be provided continuously, and the width is not particularly limited, but may be selected within the range of about 1 to 100 mm, preferably about 5 to 50 mm.

FIG. 4 shows an example in which an endless belt 17 is disposed near both ends of the metal drum 2 via a drive roll 16 so as to press the film against the drum 2. In this example, by pressing both ends of the film with the endless belt 17, the pressed part becomes thin and easily sticks to the metal drum 2, which has the advantage that shrinkage in the width direction is more effectively prevented. be. These are not only individual,
Of course, they may be used in appropriate combinations. One of the simple and economical ways to use existing equipment is to use matte-finished stainless steel foil (for example, 20mm wide
mm, thickness approximately 0.03 mm) to a metal drum and attached by welding, etc.

The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 845.0 g (4.22 mol) of 4,4'-diaminodiphenyl ether was dissolved in 10 kg of dimethylacetamide, and high-purity pyromellitic anhydride was added to this.
The amount corresponding to 920.5 g (4.22 mol) was added very accurately. The reaction vessel was maintained at 60°C.
After the reaction was completed, stirring was continued for an additional hour, resulting in a total of 3 hours. The polyamic acid resin solution thus obtained had a solid content concentration of 15% by weight and a viscosity of 2000 poise (B-type viscometer) at 23°C. To this polyamic acid resin solution, 2.5 mol of acetic anhydride and 0.5 mol of isoquinoline were added and mixed to obtain a polyamic acid organic solvent solution.
This polyamic acid organic solvent solution was supplied to a 300 mm wide slit die, extruded under pressure onto a metal drum at 80°C, and continuously coated. A stainless steel foil with a width of 20 mm and a thickness of 0.03 mm was adhered to the metal drum using an epoxy adhesive at a portion 10 mm inside the coating width. After about 3 minutes, the polyamic acid gel film was peeled off from the metal drum, both ends of the film were supported on pin sheets in the pinning process shown in FIG. 1, and the next drying process was carried out. Heat treatment is performed at 150℃ for 3 minutes in the first drying oven and 5 minutes at 400℃ in the second oven.
After post-treatment at 200°C for 1 minute, the film was wound up into a slit. It operated continuously for about 5 hours, but
During this time, the film did not shrink on the drum and the width of the film was maintained constant, the pinning process smoothly proceeded, and the film could be continuously wound.

Comparative Example 1 The polyamic acid organic solvent solution obtained in Example 1 was
A film was produced under the conditions described in Example 1 except that a metal drum without stainless steel foil was used. After about an hour, the polyamic acid gel film began to shrink in the width direction on the metal drum, and after an hour and a half, the film width became narrower than the gap between the pin sheets at both ends, making it impossible to fix the film to the pin sheets. It became. Therefore, continuous production of film was impossible.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing an example of the manufacturing apparatus of the present invention, and FIGS. 2 to 4 are all schematic views showing embodiments of the means for preventing film shrinkage and movement in the present invention. 1... Slit die, 2... Metal (casting) drum, 11... Convex portion, 12... Concave portion, 1
3...Small protrusion, 14...Shrink Teflon tube,
15... Rough surface portion, 16... Drive roll, 17...
...Endless belt.

Claims (1)

[Claims] 1 An organic solvent solution of polyamic acid, which is a precursor of polyimide, is extruded or cast onto a carrier such as a metal drum or endless belt using a slit die or coating machine, and after forming a self-supporting film by heating, it is continuously coated from the carrier. In a method for producing a polyimide film in which the polyimide film is peeled off and then subjected to post-treatment such as dry heat treatment, (a) recesses and/or protrusions provided near both ends of the carrier in parallel to the direction of travel;
(b) A rough surface part provided near the end of the carrier in parallel to the traveling direction; and (c) An endless belt provided near both ends of the carrier so as to press the film. A method for producing a polyimide film, which comprises fixing both ends of a supporting film on a carrier to prevent the film from shrinking and moving.