JP2003238707A - Polyamide image film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To industrially prepare a polyamide imide film having high heat resistance and mechanical strengths, causing very little coloring and available singly as a film for a variety of base materials. <P>SOLUTION: The film is formed continuously by continuously applying a solution of a polyamide imide having a logarithmic viscosity equal to or higher than a specified value, which is constituted of trimellitic type aromatic acid residues and cyclohexanedicarboxylic type alicyclic acid residues and drying the applied solution and winding the dried material. The resultant film has high heat resistance and mechanical strengths, good colorless transparency: it has a glass transition temperature of 150°C or higher, a logarithmic viscosity of 0.5 dl/g or higher, an average light transmittance of 80% or higher in the range of wavelengths from 400 to 500 nm and a color difference, (b) value, of below 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel polyamideimide film. More specifically, it is industrially provided with a polyamide-imide film having excellent heat resistance and transparency, which is useful as an optically isotropic substrate for liquid crystal displays, a retardation plate, a cover film of a polarizing film, a film for a color filter, etc. Is.

[0002]

2. Description of the Related Art Polyamideimide resins generally have high strength and are excellent in heat resistance, chemical resistance and electrical insulation, but since they are colored, the applications of films formed from the resins are It was limited. For example, Japanese Patent Laid-Open No. 08-11
3646 and JP-A-08-283356 disclose a polyamide-imide resin composition having a light transmittance of 75% or more at a wavelength of 500 nm at a dry film thickness of 30 μm and a varnish thereof. However, the film obtained from the varnish is excellent in transparency in the case of a thin film having a film thickness of 30 μm. However, when the film thickness is increased, the coloring becomes deep and good light rays in the 400 nm to 550 nm region, which is a feature of the present invention. The transmittance cannot be expressed.
Further, more importantly, since it is premised on coating the support as a varnish, the film-forming property and mechanical strength for being able to be used as various base materials independently as a film are not taken into consideration. It was difficult to continuously form a film having a desired strength.

[0003]

Conventionally, heat-resistant films having a high glass transition temperature have been difficult to apply to optical applications such as substrate members of liquid crystal display cells and plastic lenses because they are colored. The conventional polyamide-imide film has the same problem. An object of the present invention is to industrially provide a polyamide-imide film that does not impair mechanical strength and heat resistance, has very little coloration, and can be used alone as various base materials as a film.

[0004]

The present inventors have arrived at the present invention as a result of extensive studies on improvement of coloring. That is, the present invention has a glass transition temperature of 150 ° C. or higher, an inherent viscosity of 0.5 dl / g or higher, and a wavelength range of 400 to 550 n.
It is a polyamide-imide film having a light transmittance of 80% or more at m and a color difference b value of less than 1.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A preferable structure of the main component polymer constituting the polyamideimide film used in the present invention is, for example, that the main acid component is a trimellitic acid-based aromatic acid or acid anhydride compound and a cyclohexanedicarboxylic acid-based oil. It is a polyamide-imide which is a cyclic acid. More preferred is a polyamideimide having a cyclohexanedicarboxylic acid content of 15 mol% or more. Moreover, the polyamide imide whose amine residue is 4,4′-dicyclohexylmethane and / or isophorone is preferable.

The polyamide-imide used in the present invention is
For example, a high-boiling polar solvent such as an amide-based solvent by an ordinary method such as an isocyanate method obtained by a reaction between an acid component and an isocyanate, an amine method obtained by a reaction between an acid component and an amine component, or an acid chloride method. Is synthesized in.

Examples of the acid component used in the synthesis of the polyamideimide of the present invention include polyvalent carboxylic acids, acid chlorides, and acid anhydrides. Examples of acid anhydrides include, for example, trimellitic acid anhydride, ethylene glycol bisanhydride trimellitate, propylene glycol bisanhydride trimellitate, 1,4-
Alkylene glycol bis-anhydride trimellitates, butanediol bis-anhydride trimellitates, hexamethylene glycol bis-anhydride trimellitates, polyethylene glycol bis-anhydride trimellitates, polypropylene glycol bis-anhydride trimellitates, etc. Acid anhydride, benzophenone tetracarboxylic acid anhydride, 3,3 ', 4,4'
-Diphenyl sulfone tetracarboxylic acid anhydride, 3,
3 ', 4,4'-diphenyltetracarboxylic acid anhydride,
4,4′-oxydiphthalic anhydride and the like can be mentioned.

As the polycarboxylic acid, terephthalic acid, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenyletherdicarboxylic acid, 4,
4'-biphenyl sulfone dicarboxylic acid, 4,4'-benzophenone dicarboxylic acid, pyromellitic acid, trimellitic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 3,3', 4,4'-biphenyl sulfone tetracarboxylic acid, 3,3 ', 4,4'-biphenyl tetracarboxylic acid, adipic acid, sebacic acid, maleic acid,
Fumaric acid, dimer acid, stilbene dicarboxylic acid,
Examples thereof include 1,4-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic acid, and examples of the acid chloride include acid chlorides of the above polyvalent carboxylic acids.

As the isocyanate component, dicyclohexylmethane 4,4'-diisocyanate, 1,
3-bis (isocyanatomethyl) cyclohexane,
2,4-Tolylene diisocyanate, 2,6-Tolylene diisocyanate, Diphenylmethane 4,4'-diisocyanate, 3,3'-Dichlorodiphenyl 4,4'-
Diisocyanate, 3,3′-dimethylbiphenyl 4,
4'-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate and the like can be mentioned.

As the diamine component, 4,4'-
Diaminodicyclohexylmethane, 1,3-cyclohexanebis (methylamine), orthochloroparaphenylenediamine, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylether,
3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone,
3,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 2,2'-bis (aminophenyl) propane,
2,4-tolylenediamine, 2,6-tolylenediamine, p-xylenediamine, isophoronediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine and the like.

The acid component and the isocyanate (amine) component may be used individually or as a mixture of two or more types. As the acid component, a mixture of trimellitic acid and cyclohexanedicarboxylic acid is preferable, and cyclohexane is preferable. The content of dicarboxylic acid is particularly preferably 15 mol% or more. Cyclohexanedicarboxylic acid mol% is 1
When it is 5 or less, the coloring becomes large, and when it is used as a film, it may not be used for optical applications and the applications are limited.

As the isocyanate component, dicyclohexylmethane 4,4'-diisocyanate and isophorone diisocyanate are preferably used alone or as a mixture in view of light transmittance, heat resistance and productivity. As the amine component, dicyclohexylmethane 4,4′-diamine and isophoronediamine are preferably used alone or as a mixture in view of the light transmittance, heat resistance and productivity.

The solvent used in synthesizing the polyamideimide of the present invention is a high boiling point polar solvent such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylurea, dimethylsulfoxide, γ-butyrolactone, dimethylimidazolyldinone. A single solvent or a mixed solvent may be used, but the solvent is not limited thereto.

The polyamide-imide of the present invention is synthesized by stirring in the above-mentioned solvent at 50 to 250 ° C., preferably 80 to 230 ° C. In order to accelerate the reaction, triethylamine, lutidine, picoline, triethylenediamine, Such as amines, lithium methylate, sodium methylate, lithium ethylate, sodium ethylate, magnesium ethylate, potassium butoxide, potassium fluoride, alkali metal such as sodium fluoride, alkaline earth metal compound, or cobalt Alternatively, it may be carried out in the presence of a catalyst such as a metal such as titanium, tin, zinc or zinc, a semimetal compound or the like.

The polyamideimide thus obtained has a logarithmic viscosity (25 ° C. in N-methylpyrrolidone, polymer concentration: 0.5 g / 100 ml) of 0.5 dl / g or more. Then, 0.6 dl / g
The above is preferable. As a means for obtaining the resin having these logarithmic viscosities, a method of controlling the equivalent ratio of the reaction components, the order of addition, the reaction time, the reaction temperature and the like can be used, but the method is not limited thereto.

In order to improve the productivity of producing a film from a reaction solution composed of the polyamideimide thus synthesized and a polar solvent having a high boiling point, it is possible to replace the solvent species with a solvent having a low boiling point. For example, the polyamide-imide high-boiling point polar solvent solution (resin composition) obtained by synthesis is put into a solvent (coagulation bath) that is a non-solvent of polyamide-imide and that is mixed with the high-boiling point polar solvent to reprecipitate. Further, from the resin composition, the high boiling point polar solvent is effectively eluted, in order to adjust the elution rate, ethylene glycol, alcohol solvents such as triethylene glycol, toluene, hydrocarbon solvents such as xylene, acetone, Ketone solvents such as methyl ethyl ketone, tetrahydrofuran, dioxane, ether solvents such as ethylene glycol dimethyl ether, ester solvents such as methyl acetate and ethyl acetate,
An aqueous solvent such as water, alkaline water, acidic water, or salt-containing water may be added to the coagulation bath.

Further, the elution of the high boiling point polar solvent can be further accelerated by lowering the polymer concentration of the resin composition or raising the temperature of the coagulation bath. The coagulation bath used in the present invention is preferably water. The method of adding the resin composition to the coagulation bath is not particularly limited, but in order to continuously and efficiently produce it, it is preferable to discharge the resin composition from a fine pore nozzle.

The reprecipitated polymer is filtered, desolvated by centrifugation or the like, dried, and then redissolved in a low boiling point solvent for improving the film production efficiency. Examples of the main solvent used for re-dissolution in the present invention include alcohol solvents. The alcohol solvent is not particularly limited, and examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, pentyl alcohol, hexyl alcohol, and heptyl alcohol. Examples thereof include monohydric aliphatic alcohols such as octyl alcohol, polyhydric alcohols such as ethylene glycol, propylene glycol, tetramethylene glycol, glycerin, trimethylolpropane and penerythritol, and aromatic alcohols such as benzyl alcohol.

These alcohols can be used as a mixture with other highly volatile organic solvents from the viewpoint of film production efficiency. As other highly volatile organic solvents,
For example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexane, ester solvents such as methyl acetate, ethyl acetate, cellosolve acetate and γ-butyrolactone, hydrocarbon solvents such as benzene, toluene and xylene, tetrahydrofuran, 1 ，
Examples include ether solvents such as 4 dioxane.

The polyamide-imide film of the present invention can be obtained by removing the solvent from the resin composition obtained as described above by an arbitrary method. For example, a polyamide-imide resin composition containing a solvent, a die coater, a gravure coater, a reverse roll coater, a doctor blade coater, a nozzle coater, a comma coater, etc., any support, drum or belt conveyor in any thickness. After coating and transporting, a method of removing the solvent by heat treatment under normal pressure or reduced pressure can be mentioned. The heat treatment is not particularly limited in conditions such as temperature and temperature gradient in the heat treatment as long as the solvent in the resin composition is removed and uniform thickness accuracy can be obtained.

The preferred thickness of the film varies depending on the application, but is usually in the range of 1 μm to 1000 μm, preferably 30 μm to 500 μm.

The polyamideimide film obtained in the present invention has a Tg of 150 ° C. or higher. If the Tg is lower than 150 ° C, the dimensional stability and strength of the film at high temperatures are insufficient, so it is necessary to set the temperature to 150 ° C or higher. The Tg of the film can be controlled by controlling the ratio of aromatic residues, alicyclic residues and aliphatic residues in the skeleton of polyamideimide. Further, the polyamideimide film obtained in the present invention has an inherent viscosity of 0.5 dl / g or more. If the logarithmic viscosity is less than 0.5 dl / g, the refractive strength of the film will decrease. In addition, the yield is greatly reduced when manufacturing the film, making it difficult to continuously wind the film. The polyamide-imide film obtained by the present invention has a wavelength of 400 nm for use in optical applications, for example.
It is a colorless and transparent film having an average light transmittance of 80% or more from nm to 550 nm and a color difference b value of less than 1. Further, since it is produced by solution casting, it is a film having excellent optical isotropy and is suitable for optical use.

In the film of the present invention, a lubricant can be added in order to improve the handleability of the film as long as the optical properties such as colorless transparency are not impaired. As a lubricant, silicon dioxide, kaolin, clay, calcium carbonate, calcium terephthalate, aluminum oxide,
Examples thereof include fine particles of inorganic compounds or organic metal salts such as titanium oxide, calcium phosphate, silicone particles, and talc, and organic fine particles such as polyolefin-based or acrylic-based particles. These are not particularly limited as long as they are dissolved or dispersed in the polyamideimide solution. In addition to the lubricant, if necessary, additives such as a stabilizer, a colorant, an antioxidant, an antifoaming agent and an antistatic agent may be added.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The characteristics shown in the examples are measured and evaluated by the following methods.

(Measurement / Evaluation Method) 1. Glass transition temperature The glass transition temperature was defined as the temperature showing the main dispersion of the loss tangent tan δ obtained by dynamic viscoelasticity measurement. For dynamic viscoelasticity measurement, a sample with a width of 5 mm and a test length of 25 mm was measured by a dynamic viscoelasticity measuring device (D
VA-220) at a measurement frequency of 10 Hz and a heating rate of 5 ° C./min in the range of room temperature to 300 ° C. 2. Logarithmic viscosity The logarithmic viscosity was defined by the following formula. (Logarithmic viscosity) = (ln ηrel) / C ln: natural logarithm, ηrel: viscosity ratio of solution to pure solvent by solvent drop time measurement (−), C: concentration of solution (g / dl) measurement of 0.5 g 100m of polymer or film
The solution obtained by dissolving in 1 N-methylpyrrolidone was carried out at 25 ° C. using an Ubbelohde viscosity tube.

3. The light transmittance in the wavelength region 400 to 550 nm was measured at a scan speed of 100 nm / min using an average light transmittance spectrophotometer (U-2001 manufactured by Hitachi, Ltd.) in the wavelength region 400 to 550 nm, and 400 nm, 450 n
The average value of the transmittances of m, 500 nm and 550 nm was defined as the average light transmittance in the wavelength region 400 to 550 nm. 4. Color difference b-value color difference meter (Color Meter Z manufactured by Nippon Denshoku Industries Co., Ltd.
E2000) in transmission mode. As a standard sample, tristimulus values are X = 93.08 and Y = 9, respectively.
An attached standard white plate with 5.03 and Z = 111.69 was used.

5. Tensile strength, tensile elongation width of 10 mm, test length of 40 mm, using a tensile tester (Autograph AG5000A manufactured by Shimadzu Corporation), a tensile speed of 200 mm / min, other conditions are JIS
It was determined from the stress-strain curve obtained by measurement according to C2318.

(Reference Example 1) Trimellitic anhydride; 15 mol; cyclohexanedicarboxylic acid; 15 mol; isophorone diisocyanate;
85 mol, potassium fluoride; 0.1 mol, γ-butyrolactone; 9.48 kg were added, and the mixture was stirred at 120 ° C.
After reacting for 1.5 hours at 190 ° C. for 5 hours,
It was cooled to room temperature while adding N-methylpyrrolidone to dilute the polymer concentration to 20% by weight. Add this solution to 10
After gradually adding to 0 liter of ion-exchanged water with stirring for 1 hour to precipitate a polymer while washing, the polymer was further stirred and washed at 50 ° C in ion-exchanged water, filtered and then 60 ° C.
And dried under reduced pressure for 10 hours. The polyamideimide obtained had an inherent viscosity of 0.70 dl / g.

(Reference Example 2) Trimellitic anhydride; 6 mol; cyclohexanedicarboxylic acid; 24 mol; isophorone diisocyanate; 29.8 in a 100 liter polymerization kettle.
5 mol, sodium methoxide; 0.1 mol, γ-butyrolactone; 9.48 kg were added, and polymerization, dilution, reprecipitation and drying were carried out in the same manner as in Reference Example 1 to obtain a logarithmic viscosity of 0.73 d.
1 / g of polyamideimide was obtained.

Reference Example 3 In Reference Example 1, trimellitic anhydride was used without using cyclohexanedicarboxylic acid;
A polyamideimide having a logarithmic viscosity of 0.70 dl / g was obtained in the same manner as in Reference Example 1 except that the amount was 30 mol.

Reference Example 4 A polyamideimide having a logarithmic viscosity of 0.46 dl / g was obtained in the same manner as in Reference Example 1 except that the reaction time at 190 ° C. was 2.5 hours.

Example 1 9 kg of the polyamideimide obtained in Reference Example 1; 9 kg of toluene; 13.5 kg of ethanol; 13.5 kg of ethanol were dissolved in a mixed solvent with stirring at 25 ° C. for 10 minutes, and then allowed to stand for 24 hours. Then, defoaming was performed to obtain 36 kg of a 25% by weight polyamideimide solution. Using this, a film forming test was carried out using a solution film forming apparatus having a coat die and a drying facility equipped with a float nozzle. That is, the polyamide imide solution left standing in the hopper was fed into a coat die by a gear pump to give a coating film width of 6
After being cast on a PET film base material with a film thickness of 00 mm and a coating thickness of 400 μm, the wind speed of the film base material is 15 m / sec.
Continuously fed into the drying oven of 60 ° C., dried at 60 ° C. for 1 minute, 70 ° C. for 1 minute, and 100 ° C. for 1 minute.
The polyamide film on the ET film substrate was peeled off and continuously wound. The wound film is further reduced under pressure 20
By drying at 0 ° C. for 3 hours, a polyamide-imide film having a thickness of about 100 μm was obtained. The properties of the obtained polyamide-imide film are shown in Table 1. A polyamideimide film having excellent transparency and suitable for optical applications was obtained.

Example 2 N in the process of Reference Example 1
With respect to a polyamideimide solution having a polymer concentration of 20% by weight using methylpyrrolidone as a solvent, the polymer was allowed to stand for 24 hours for defoaming without precipitating the polymer, and a film forming test was conducted in the same manner as in Example 1. However, in that case, the drying conditions in the tester are 60 ° C for 5 minutes, 90 ° C for 5 minutes, and
It was 5 minutes at 20 ° C. The properties of the obtained polyamide-imide film are shown in Table 1. A polyamideimide film having excellent transparency and suitable for optical applications was obtained.

Example 3 The polyamideimide obtained in Reference Example 2 (9 kg) was dissolved in a mixed solvent of toluene (13.5 kg) and ethanol (13.5 kg) at 25 ° C. for 10 minutes with stirring at 25 ° C., and the mixture was allowed to stand for 24 hours. Then, defoaming was performed to obtain 36 kg of a 25% by weight polyamide imide solution. Using this, a film forming test was conducted in the same manner as in Example 1. The properties of the obtained polyamide-imide film are shown in Table 1. A polyamideimide film having excellent transparency and suitable for optical applications was obtained.

Comparative Example 1 The polyamideimide obtained in Reference Example 3 (9 kg) was dissolved in a mixed solvent of toluene (13.5 kg) and ethanol (13.5 kg) at 25 ° C. for 10 minutes with stirring, and the mixture was allowed to stand for 24 hours. Then, defoaming was performed to obtain 36 kg of a 25% by weight polyamide imide solution. Using this, a film forming test was conducted in the same manner as in Example 1. The properties of the obtained polyamide-imide film are shown in Table 1. The polyamide-imide film was not suitable for colored optical use.

(Comparative Example 2) The polyamideimide obtained in Reference Example 4 (9 kg) was dissolved in a mixed solvent of toluene (13.5 kg) and ethanol (13.5 kg) at 25 ° C for 10 minutes with stirring, and the mixture was allowed to stand for 24 hours. Then, defoaming was performed to obtain 36 kg of a 25% by weight polyamide imide solution. Using this, film formation was performed in the same manner as in Example 1. During film formation, the film was torn in the peeling process and could not be continuously wound. The torn polyamide imide film had an inherent viscosity of 0.46 dl / g.

[0037]

[Table 1]

[0038]

The polyamide-imide film of the present invention is
Its excellent heat resistance and mechanical strength as well as its colorless and transparent properties make it widely used for optically isotropic substrates for liquid crystal displays, retarders, polarizing film cover films, color filter films, etc. can do. Further, since the film can be continuously formed and provided in a rolled-up form as a long film, it is extremely useful industrially.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chika Morishige             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Toshiyuki Otani             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Jun Yamada             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Yasushi Aikawa             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. F-term (reference) 4F071 AA60 AA86 AA88 AF30 AH12                       BB02 BC01                 4J043 PA04 QB58 RA05 SA11 TA21                       UA011 UA122 XA03 XA19                       ZB11 ZB47

Claims (2)

[Claims] 1. A glass transition temperature of 150 ° C. or higher, a logarithmic viscosity of 0.5 dl / g or higher, and a wavelength range of 400 to 550 nm.
The average light transmittance is 77% or more and the color difference b value is less than 1, the polyamide-imide film. 2. The polyamide-imide film according to claim 1, wherein the polyamide-imide film is mainly composed of trimellilitic acid-based aromatic acid residues and cyclohexanedicarboxylic acid-based alicyclic acid residues.