JPH04278344A - Transparent film heving moistureproofness and heat resistance - Google Patents

Abstract

PURPOSE:To obtain a transparent film excellent in moistureproofness and heat resistance and especially suitable for an optical film in a field of optoelectronics by forming an amorphous polyolefin layer to at least one surface of an amorphous aromatic polymer film. CONSTITUTION:A transparent film is obtained by forming an amorphous polyolefin layer to at least one surface of an amorphous aromatic polymer film and, as the amorphous aromatic polymer film, respective films composed of polyetherimide, polyether sulfone and aromatic polyester are designated but the amorphous aromatic polyester film is pref. from the aspect of transparency and heat resistance. As this amorphous polyester film, a film obtained by the reaction of terephthalic acid, isophthalic acid or a mixture of both of them with divalent phenols represented by general formula (wherein P and q are an integer of 0-4 and R<1> and R<2> are a 1-4 alkyl group) is used.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent film having moisture resistance and heat resistance, and more particularly, to a transparent film that can be suitably used as an optical film in the field of optoelectronics, for example.

0002

[Background Art] In recent years, in the field of optoelectronics, highly transparent optical films with excellent moisture resistance and heat resistance have been required. Regarding, vinylidene chloride on this film surface,
Attempts have been made to improve moisture resistance by forming a moisture barrier layer made of polypropylene or the like.

0003

[Problems to be Solved by the Invention] However, when the moisture barrier layer is formed from vinylidene chloride, there are disadvantages in that it becomes colored and generates hydrochloric acid gas at temperatures above 100°C, and when it is formed from polypropylene, had the disadvantage that transparency deteriorates when the temperature exceeds 150°C. The present invention was made in view of the above circumstances, and its object is to provide a transparent film that has excellent moisture resistance and heat resistance, and is highly transparent, which can be suitably used as an optical film.

0004

[Means for Solving the Problems] A transparent film according to the present invention for achieving the above object is formed by forming an amorphous polyolefin layer on at least one surface of an amorphous aromatic polymer film.

[0005] Examples of the amorphous aromatic polymer film in the present invention include polyetherimide, polyether sulfone, and aromatic polyester films. Among these, an amorphous aromatic polyester film is preferred in terms of transparency and heat resistance. Such an amorphous aromatic polyester film is obtained by reacting terephthalic acid, isophthalic acid, or a mixture of terephthalic acid and isophthalic acid with a dihydric phenol represented by the general formula shown in Chemical Formula 2. An example is film.

[0006]

[Case 2]

[In the formula, p and q are integers of 0 to 4, R1,
R2 is an alkyl group having 1 to 4 carbon atoms, which may be the same or different, and p or q is 2 to 2;
4, each R1 and R2 may be the same or different from each other. In addition, X is a direct bond, an alkylene group, an alkylidene group (the hydrogen atom in these alkylene groups and alkylidene groups may be substituted with a hydrocarbon group, a halogen group, or a halogenated hydrocarbon group), -O-, −
S-, -SO-, -SO2- or -CO-. ]

Specific examples of the dihydric phenol represented by the general formula shown in Chemical Formula 2 include 2,2-bis(4'-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, and 2,2-bis(4'-hydroxyphenyl)propane. (4'-hydroxyphenyl)
Butane, 3,3-bis(4'-hydroxyphenyl)pentane, 4,4-bis(4'-hydroxyphenyl)heptane, 4,4'-(α-methylbenzylidene)bisphenol, 4,4-bis(4'-hydroxyphenyl)pentane, '-hydroxyphenyl)
-2,5-dimethylheptane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4'-hydroxyphenyl)octane, bis(4'-hydroxyphenyl)-4-fluorophenylmethane, bis(3, 5
-dimethyl-4hydroxyphenyl)methane, 2,2-
Bis(3',5'-dimethyl-4'-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)phenylethane, bis(3-methyl-4-
hydroxyphenyl)diphenylmethane, bis(3,5
-dimethyl-4-hydroxyphenyl) sulfone is exemplified. These may be used alone or in combination of two or more if necessary.

The above-mentioned amorphous aromatic polymer film can be obtained, for example, by extrusion molding or casting from a solution of an amorphous aromatic polymer dissolved in a solvent. Among these, the casting method is preferred in terms of uniformity of film thickness and leveling of the surface. The film thickness is usually several μm to 800 μm, preferably 10 to 300 μm.
It is. In cases where the film may be subjected to high temperature treatment in the processing process, the above-mentioned amorphous aromatic polyester film, which has particularly excellent heat resistance, is suitable as the amorphous aromatic polymer film.

[0010] The amorphous polyolefin layer in the present invention functions as a moisture-proof layer. If this moisture-proof layer is made of crystalline polyolefin such as polypropylene, crystallization will occur gradually during the heating-cooling cycle during the processing process, resulting in low transparency, especially HAZE.
This results in a large film. In order to prevent this, it is necessary to limit the upper limit heating temperature to about 150°C, which poses a problem in processing. However, in the present invention, the moisture-proof layer is formed of an amorphous polyolefin that has excellent heat resistance. Therefore, even if heating-cooling cycles are repeated, crystallization does not occur and transparency does not deteriorate. Amorphous polyolefins are generally 10% lower than their glass transition point (Tg).
The limit of heat resistance (usable temperature) is approximately 20°C lower than the Tg of amorphous polyolefin, but if an aromatic polyester film with excellent heat resistance is used as the base film, the temperature is 50°C or more lower than the Tg of amorphous polyolefin. Even when heated to high temperatures, the film can be composited without deforming the amorphous polyolefin layer. In addition, when manufacturing a liquid crystal display device by combining the transparent film according to the present invention with a transparent conductive film, the Tg is 12 due to the processing process.
It is preferable to use an amorphous polyolefin having a temperature of 0°C or higher. The thickness of the amorphous polyolefin layer is preferably in the range of 1 μm to about 2/5 of the thickness of the base film,
More preferably, the range is from 5 μm to about 3/10 of the thickness of the base film. If it becomes thinner than 1 μm, the moisture proofing properties will be insufficient, and if it becomes thicker than 2/5 of the thickness of the base film, the heat resistance of the resulting composite film will decrease. Examples of the above-mentioned amorphous polyolefins include those made by cyclizing an olefin to increase its Tg and make it amorphous. Commercially available products include Zeonex (trade name) manufactured by Nippon Zeon Co., Ltd. and Zeonex (trade name) manufactured by Mitsui Petrochemicals Co., Ltd. Examples include APO resin.

[0011] In the production of the composite film according to the present invention, an amorphous aromatic polymer film and an amorphous polyolefin may be dry laminated, or an amorphous aromatic polymer film may be laminated with an amorphous polyolefin. After the polyolefin solution is cast, it may be dried. Further, an appropriate adhesive may be used to increase the adhesion strength between the two. Furthermore, if necessary, a transparent hard coat layer for surface protection or a gas barrier layer may be formed on one or both sides of the transparent film according to the present invention. The transparent film according to the present invention can be suitably used in the optoelectronics field. That is, for example, glass is currently mainly used as the transparent electrode of liquid crystal display elements, but by replacing it with the transparent film according to the present invention, it can be made lightweight, hard to break, and has excellent heat resistance and moisture resistance. Therefore, it becomes possible to obtain a display element with a high temperature.

0012

[Examples] The present invention will be explained in more detail based on Examples below, but the present invention is not limited to the following Examples in any way, and may be practiced with appropriate modifications within the scope of the gist thereof. is possible.

(Example 1) (A) Synthesis of amorphous aromatic polyester 2,2-bis(
Add 1.14 g of 4'-hydroxyphenyl)propane, 1.28 g of bis(3,5-dimethyl-4-hydroxyphenyl)methane, and 1.5 g of para-t-butylphenol to 20 ml of a 1.25 N NaOH aqueous solution. I melted it. To this aqueous solution, add 1 terephthalic acid chloride.
．． A solution of 91 g and 0.04 g of trioctylmethylammonium chloride (phase transfer catalyst) dissolved in 20 ml of orthodichlorobenzene was added, and the mixture was reacted for 3 hours at room temperature while stirring. After decanting the aqueous layer of the reaction mixture, the same amount of water was added to the organic layer, and the mixture was neutralized with a small amount of hydrochloric acid. Further, the organic layer was washed with water five times and then poured into a large amount of methanol to precipitate a solid aromatic polyester. The yield of polyester at this time is almost 100%.
Met. Also, the Tg of this polyester is 250°C
The reduced viscosity ηsp/c, which is an index of molecular weight, is 0.60.
(0.32 g/dl in chloroform at 32°C). (B) Preparation of amorphous aromatic polyester film (
The polyester obtained in A) was dissolved in methylene chloride to a concentration of 15% by weight, the resulting solution was cast onto a SUS plate, placed on a hot plate, and heated at 50°C for 2 hours.
The film was heat-set at 0 minutes, 100°C for 20 minutes, 150°C for 20 minutes, and 250°C for 10 minutes to obtain a film with a thickness of about 70 μm. (C) Preparation of composite film Zeonex manufactured by Nippon Zeon Co., Ltd. as an amorphous polyolefin was dissolved in toluene to obtain a 20% solution. This solution was cast on the amorphous aromatic polyester film obtained in (B) above to form a moisture-proof layer with a thickness of 20 μm. Above (B)
Table 1 shows the optical properties (total light transmittance and haze) and moisture permeability of each film obtained in (C). Also, 180°
The optical properties and moisture permeability after heating at C for 1 hour are also listed. Total light transmittance and haze were measured in accordance with ASTM D1003, and moisture permeability was measured in accordance with JIS Z 0208.

[0014]

[Table 1]

From Table 1, it can be seen that there is almost no change in the optical properties or moisture permeability after heating. Further, no changes in appearance such as wrinkles or shrinkage were observed in the film after heating.

(Example 2) (A) Synthesis of amorphous aromatic polyester 2,2-bis(
20.11 g of 4'-hydroxyphenyl)propane, 15.06 g of bis(3,5-dimethyl-4-hydroxyphenyl)methane, 0.95 g of para-t-butylphenol
g, sodium hydrosulfite 0.26g, 5N
-NaOH aqueous solution 78.2ml, water 176.8ml
The milliliters were mixed in a 300 ml eggplant type flask under a nitrogen atmosphere and cooled to 5°C to prepare an alkaline aqueous solution of dihydric phenol. On the other hand, terephthalic acid chloride 21.32g, isophthalic acid chloride 9.
14 g was dissolved in 255 ml of methylene chloride in a 300 ml eggplant-shaped flask under a nitrogen atmosphere.
Cooled to 5°C. Also, in a 1 liter separable flask, 137 ml of water and 0.16 g of benzyltributylammonium chloride (phase transfer catalyst).
was charged under nitrogen atmosphere and cooled to 5°C. While stirring the cooling liquid vigorously, add 1 portion of each of the above two liquids at the same time.
Added continuously by pump over 0 minutes. This addition is complete 2
After an hour, a solution of 0.42 g of benzoyl chloride dissolved in 5 ml of methylene chloride was added, and stirring was stopped after 20 minutes. After decanting the aqueous layer, the same amount of water was added and neutralized with a small amount of hydrochloric acid while stirring. After repeated desalting by decanting and washing with water, dilute with 300 ml of methylene chloride, heat this solution to 40-50 °C, and remove the water in the methylene chloride solution of the polyester by azeotropic dehydration with methylene chloride. The methylene chloride was then distilled until the polymer concentration was 15% by weight. The reduced viscosity ηsp/c of this polyester is 0.90 (32°C
, 0.32 g/dl in chloroform). (B) Preparation of amorphous aromatic polyester film (
The methylene chloride solution of the polyester obtained in A) was cast onto a SUS plate, placed on a hot plate, and heated at 50°.
Heat set at C for 20 minutes, 100°C for 20 minutes, 150°C for 20 minutes, and 250°C for 10 minutes to approximately 70 μm.
A thick film was obtained. (C) Preparation of composite film Zeonex manufactured by Nippon Zeon Co., Ltd. as an amorphous polyolefin was dissolved in toluene to obtain a 20% solution. This solution was cast on the amorphous aromatic polyester film obtained in (B) above to form a moisture-proof layer with a thickness of 20 μm. Above (B)
Table 1 shows the optical properties (total light transmittance and haze) and moisture permeability of each film obtained in (C). Table 1 also lists the optical properties after heating at 180°C for 1 hour. From Table 1, it can be seen that there is no change in the optical properties after heating. Further, no changes in appearance such as wrinkles or shrinkage were observed in the film after heating.

(Example 3) (A) Synthesis of amorphous aromatic polyester 4,4'-(α
-methylbenzylidene)bisphenol 30.45g,
1.58 g of para-t-butylphenol, 0.53 g of sodium hydrosulfite, 153 ml of 5N-NaOH aqueous solution, and 361 ml of water were mixed in a 1.5 liter separable flask under a nitrogen atmosphere and heated to 5°C. The mixture was cooled to prepare an alkaline aqueous solution of dihydric phenol. On the other hand, terephthalic acid chloride 30.45
g and 30.45 g of isophthalic acid chloride were dissolved in 500 ml of methylene chloride in a 1 liter flask under a nitrogen atmosphere and cooled to 5°C. Further, 200 ml of water and 0.31 g of benzyltributylammonium chloride (phase transfer catalyst) were placed in a 1-liter separable flask under a nitrogen atmosphere, and the flask was cooled to 5°C. While stirring the cooling liquid vigorously, the above two liquids were simultaneously and continuously added to each liquid over a period of 10 minutes using a pump. Two hours after the end of this addition, 0.0% of benzoyl chloride was added.
A solution of 42 g dissolved in 5 ml of methylene chloride was added, and stirring was stopped after 20 minutes. After decanting the aqueous layer, the same amount of water was added and neutralized with a small amount of hydrochloric acid while stirring. After repeated desalting by decanting and washing with water, diluted with 300 ml of methylene chloride, and the solution was
The solution was heated to 0 to 50°C, water was removed from the polyester solution in methylene chloride by azeotropic dehydration with methylene chloride, and the methylene chloride was further distilled until the polymer concentration was 15% by weight. The reduced viscosity ηsp/c of this polyester is 0
．． 80 (32°C, 0.32 g/dl in chloroform). In addition, TMA (Thermo Me
The Tg determined by the chemical analysis method was 240°C. (B) Preparation of amorphous aromatic polyester film (
The methylene chloride solution of the polyester obtained in A) was cast onto a SUS plate, placed on a hot plate, and heated at room temperature for 1 hour.
Heat setting was performed at 150°C for 15 minutes and then at 250°C for 10 minutes to obtain a film with a thickness of approximately 70 μm. (C) Preparation of composite film Zeonex manufactured by Nippon Zeon Co., Ltd. as an amorphous polyolefin was dissolved in toluene to obtain a 20% solution. This solution was cast on the amorphous aromatic polyester film obtained in step B above to form a moisture-proof layer with a thickness of 20 μm. Table 1 shows the optical properties (total light transmittance and haze) and moisture permeability of each film obtained in (B) and (C) above. Also, Table 1 shows 18
The optical properties after heating at 0°C for 1 hour are also shown. Table 1
It can be seen that there is no change in the optical properties after heating. Further, no changes in appearance such as wrinkles or shrinkage were observed in the film after heating.

(Example 4) (A) Synthesis of amorphous aromatic polyester bis(3,5-
dimethyl-4-hydroxyphenyl)sulfone 36.2
1g, para-t-butylphenol 0.95g, sodium hydrosulfite 0.25g, 5N-NaOH
58 ml of the aqueous solution and 200 ml of water were mixed in a 300 ml eggplant-shaped flask under a nitrogen atmosphere, and the mixture was cooled to 5°C to prepare an alkaline aqueous solution of dihydric phenol. On the other hand, terephthalic acid chloride 12.
18 g and 12.18 g of isophthalic acid chloride were added to 250 ml of methylene chloride under a nitrogen atmosphere for 300 g.
The mixture was dissolved in a milliliter eggplant-shaped flask and cooled to 5°C. Also, in a 1 liter separable flask, add 10 liters of water.
0 ml and 0.14 g of trioctylmethylammonium chloride (phase transfer catalyst) were charged under a nitrogen atmosphere and similarly cooled to 5°C. While stirring the cooling liquid vigorously, the above two liquids were simultaneously and continuously added to each liquid over a period of 10 minutes using a pump. Two hours after the end of this addition, 0.21 g of benzoyl chloride was added to 5 ml of methylene chloride.
ml of the solution was added and stirring was stopped after 20 minutes. After decanting the aqueous layer, the same amount of water was added and neutralized with a small amount of hydrochloric acid while stirring. After repeated desalting by decanting and washing with water, 300 ml of methylene chloride was added to dilute the solution, and the solution was heated to 40-50°C.
Water in the methylene chloride solution of the polyester was removed by azeotropic dehydration with methylene chloride, and the methylene chloride was further distilled until the polymer concentration was 15% by weight. The reduced viscosity ηsp/c of this polyester was 0.95 (32°C, 0.32 g/deciliter in chloroform). (B) Preparation of amorphous aromatic polyester film (
The methylene chloride solution of the polyester obtained in A) was cast onto a SUS plate, placed on a hot plate, and heated at 50°C for 2 hours.
The film was heat-set at 0 minutes, 150°C for 20 minutes, and further at 300°C for 10 minutes to obtain a film with a thickness of about 70 μm. (C) Preparation of composite film Zeonex manufactured by Nippon Zeon Co., Ltd. as an amorphous polyolefin was dissolved in toluene to obtain a 20% solution. This solution was cast on the amorphous aromatic polyester film obtained in (B) above to form a moisture-proof layer with a thickness of 20 μm. Above (B)
Table 1 shows the optical properties (total light transmittance and haze) and moisture permeability of each film obtained in (C). Table 1 also lists the optical properties after heating at 180°C for 1 hour. From Table 1, it can be seen that there is no change in the optical properties after heating. Further, no changes in appearance such as wrinkles or shrinkage were observed in the film after heating.

(Comparative Example) 7 produced in Example 2 (B)
15 μm on a 0 μm thick amorphous aromatic polyester film
A composite film was prepared by laminating m-thick polypropylene films, and tested in the same manner as in Examples 1 to 4. The results are shown in Table 1. The haze after heating at 180°C for 1 hour was large, indicating that there was a problem with heat resistance.

[0020]

Effects of the Invention The transparent film according to the present invention has excellent moisture resistance and heat resistance, and has high transparency, so that it can be suitably used as an optical film, etc., and the present invention has excellent and unique effects.

Claims (3)

[Claims] 1. A transparent film having moisture resistance and heat resistance, characterized in that an amorphous polyolefin layer is formed on at least one surface of an amorphous aromatic polymer film. 2. The amorphous aromatic polymer film comprises:
A claim that the film is an amorphous aromatic polyester film obtained by reacting terephthalic acid, isophthalic acid, or a mixture of terephthalic acid and isophthalic acid with a dihydric phenol represented by the general formula shown in Chemical Formula 1. 1. The transparent film having moisture resistance and heat resistance as described in 1. [Formula, p and q are integers of 0 to 4, R1 and R2 have carbon atoms of 1 to 4, which may be the same or different]
is an alkyl group, and when p or q is 2 to 4, each R
1 and R2 may be the same or different. In addition, X is a direct bond, an alkylene group, an alkylidene group (
Hydrogen atoms in these alkylene groups and alkylidene groups may be substituted with hydrocarbon groups, halogen groups, halogenated hydrocarbon groups), -O-, -S-, -SO-, -S
O2 - or -CO-. ] 3. The transparent film having moisture resistance and heat resistance according to claim 1 or 2, wherein the amorphous polyolefin layer is a layer made of an amorphous polyolefin having a glass transition point of 120° C. or higher.