JPH10287804A - Composition for optical functional sheet and prism sheet - Google Patents

Abstract

(57) [Summary] [Problem] Optical functionality very useful in industrial fields where transparency and transferability are required, such as optical functional sheets for OA equipment such as personal computers and electronic equipment. A composition for a sheet is provided. SOLUTION: (A) Aromatic polycarbonate resin 95
85% by weight (component A), (B) polycaprolactone 5
100 parts by weight of a resin composition comprising -15 to 15% by weight (component B) and (C) a benzotriazole-based ultraviolet absorber 0.0
A composition comprising 1 to 2.0 parts by weight (component C),
The glass transition temperature of the composition is 100 to 130 ° C.,
A composition for an optical functional sheet and a prism sheet having a total light transmittance of 90% or more in a molded product having a thickness of 2 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for an optical functional sheet having excellent transparency and transferability. More specifically, at the time of extruding the sheet, at the time of injection molding, etc., the unevenness engraved on a roll or a mold is satisfactorily transferred, and is used for a liquid crystal of a notebook computer, a car navigation system, and other electronic devices. And a composition for an optical functional sheet useful in a wide range of industrial fields.

[0002]

2. Description of the Related Art Conventionally, aromatic polycarbonate resins are excellent in mechanical strength, heat resistance and impact resistance, and are therefore melt molded by injection molding, compression molding, extrusion molding, blow molding, or the like. It has been used in many applications.

Aromatic polycarbonate resins are widely used as materials for optical functional sheets having various optical functionalities, that is, refraction, reflection, scattering, interference, deflection, etc. by processing the surface because of their excellent transparency. Have been. However, since the aromatic polycarbonate resin has a high glass transition temperature (Tg) of 145 ° C., in order to impart a specific unevenness to the thin sheet to obtain an optical functional effect, the aromatic polycarbonate resin needs to be treated once. After forming the sheet into a flat sheet, a step of pressing again a mold having specific irregularities after heating was required. In this method, not only the number of steps is increased, but also it is difficult to transfer the unevenness uniformly and sharply, so that the yield is deteriorated and the cost is difficult to reduce. For this reason, there has been a demand for a material capable of favorably transferring irregularities engraved on a roll, a releasable sheet, a mold, or the like at the time of extruding the sheet or at the time of injection molding.

Hitherto, it has been proposed to impart releasability by adding polycaprolactone to an aromatic polycarbonate resin (JP-A-51-58457 and JP-A-51-143058). The addition amount is in the range of 0.1 to 4.5% by weight, and no description is given of the relationship between the glass transition temperature and the transferability of the irregularities formed in the mold.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition for an optical functional sheet which is excellent in transparency and transferability. The present inventors have conducted intensive studies to achieve the above object, and as a result, a resin comprising (A) an aromatic polycarbonate resin of 95 to 85% by weight (component A) and (B) a polycaprolactone of 5 to 15% by weight (component B). Composition 1
A composition comprising 00 parts by weight and 0.01 to 2.0 parts by weight of (C) a benzotriazole-based ultraviolet absorber (component (C)), wherein the glass transition temperature of the composition is 100 to 130 ° C.
And the total light transmittance of the 2 mm thick molded product is 9
When the content is 0% or more, it has been surprisingly determined that a composition for an optical functional sheet having excellent transparency and excellent transferability can be obtained, and further studies have been completed to complete the present invention.

[0006]

According to the present invention, there is provided (A) 95 to 85% by weight of an aromatic polycarbonate resin (A component);
(B) Composition comprising 100 parts by weight of a resin composition comprising 5 to 15% by weight of polycaprolactone (component (B)) and 0.01 to 2.0 parts by weight of (C) a benzotriazole-based ultraviolet absorber (component (C)) The present invention relates to a composition for an optical functional sheet and a prism sheet, wherein the glass transition temperature of the composition is 100 to 130 ° C. and the total light transmittance of a molded product having a thickness of 2 mm is 90% or more. .

The aromatic polycarbonate resin (component A) used in the present invention can be produced by reacting a dihydric phenol with a carbonate precursor. Representative examples of dihydric phenols include 2,2-bis (4-hydroxyphenyl) propane [commonly known as bisphenol A], 1,1-bis (4-hydroxyphenyl) ethane, and 1,1-bis (4
-Hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-
3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like. Preferred dihydric phenols are 2,2-bis (4-hydroxyphenyl) alkanes, especially bisphenol A.

As the carbonate precursor, carbonyl halide, carbonate ester or haloformate is used, and specific examples include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol and the like. In producing aromatic polycarbonate resin,
The above-mentioned dihydric phenols can be used alone or in combination of two or more. Further, two or more kinds of the obtained aromatic polycarbonate resins may be mixed and used.

The degree of polymerization of the aromatic polycarbonate resin used as the component A is generally expressed by a viscosity average molecular weight of 1
2,000 to 30,000, preferably 15,000 to
28,000. The viscosity average molecular weight (M) in the present invention is determined from [η _sp ] using methylene chloride as a solvent by the following formula. η _sp /C=[η]+0.45×[η] ² C [η] = 1.23 × 10 ⁻⁴ M ^0.83 C = 0.7 In producing an aromatic polycarbonate having such a molecular weight, appropriate molecular weight control is performed. An agent or a catalyst for accelerating the reaction may be used.

The polycaprolactone used as the component (B) in the present invention is a polymer of caprolactone, particularly a polymer of ε-caprolactone, that is, a polymer having a repeating unit represented by the following formula.

[0011]

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A part or a repeating unit of the hydrogen atom of the methylene chain of polycaprolactone may be substituted with a halogen atom or a hydrocarbon group. The terminal of polycaprolactone may be subjected to terminal treatment such as esterification or etherification. The molecular weight of the polycaprolactone need not be particularly limited, but may be 5,000 to 4 in terms of number average molecular weight.
000 is preferred. Such polycaprolactone can be produced by ring-opening polymerization of caprolactone in the presence of a catalyst such as an acid, a base, and an organometallic compound. As a commercially available product of such polycaprolactone, there is a polycaprolactone Placcel H-1 (number average molecular weight 10,000) manufactured by Daicel Chemical Industries, Ltd. The proportion of the polycaprolactone used in the present invention is 5 to 15% by weight based on 95 to 85% by weight of the aromatic polycarbonate resin,
Preferably it is 6 to 10% by weight. If it is less than 5% by weight,
When the transferability is not sufficient and exceeds 15% by weight, the strength and thermal stability of the obtained sheet are greatly reduced, and the sheet cannot be put to practical use.

The ultraviolet absorber used as the component C in the present invention is a component necessary for preventing deterioration due to ultraviolet rays since the optical functional sheet is usually exposed to light from a light source for a long time. The ultraviolet absorber is not particularly limited as long as it is a benzotriazole-based one. For example, 2,2-methylenebis (4- (1,1,3,3,-
Tetramethylbutyl) -6-2H-benzotriazol-2-yl) phenol), 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3,5-bis (α-dimethyl) Benzyl) phenyl) -2H-benzotriazole, 2-3,5-di-
T-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, oxalic acid anilide-based 2-ethoxy-5-t-butyl-2′-ethyloxalic acid bisanilide, and the like are preferably used. .
Commercially available benzotriazole-based UV absorbers include ADK STAB LA-31 manufactured by Asahi Denka Kogyo KK
There is. The blending ratio of the benzotriazole-based ultraviolet absorber used in the present invention is 0.01 to 2.0 parts by weight, preferably 100 to 100 parts by weight of the composition comprising the aromatic polycarbonate resin and the polycaprolactone (B). 0.0
1 to 1.0 part by weight. If the amount exceeds 2.0 parts by weight, the transparency of the obtained sheet is reduced, and the sheet is not practical.

The composition of the present invention has a glass transition temperature of 100 to 130 ° C. and a total light transmittance of 90% or more in a molded product having a thickness of 2 mm. When the glass transition temperature exceeds 130 ° C. or is less than 100 ° C., transferability is not sufficient. On the other hand, if the total light transmittance of the molded product at a thickness of 2 mm is less than 90%, the resulting sheet is not sufficiently transparent, and thus cannot be put to practical use.

The optical functional sheet of the present invention includes, for example, a prism sheet. The prism sheet is widely used to increase the brightness of a liquid crystal surface used for a liquid crystal of a notebook computer or the like. As the prism sheet, a sheet having a thickness of usually 100 to 300 μm and regularly arranged irregularities having a fixed shape such as a triangular pyramid or a kamaboko pattern at a fixed pitch is exemplified.

The composition of the present invention contains other transparent thermoplastic resins (for example, polybutylene terephthalate resin, polyethylene terephthalate resin,
AS resin, etc.), flame retardant (brominated polycarbonate, triphenyl phosphate, etc.), stabilizer (eg, phosphate ester, phosphite ester, etc.), antioxidant (eg, hindered phenol compound, etc.), azo type A blue dye such as an organic dye, an anthraquinone-based organic dye, a quinophthalone-based organic dye, a perylene-based organic dye, an anthrapyridone-based organic dye, and a release agent may be appropriately blended.

For producing the composition for an optical functional sheet of the present invention, any method is employed. For example, aromatic polycarbonate resin, polycaprolactone, and other additives as appropriate, for example, after sufficiently mixing using a mixing means such as a V-type blender, a method of pelletizing with a vented single-screw ruder, an aromatic polycarbonate resin, Polycaprolactone and other additives prepared in advance by a powerful means such as a super mixer are prepared in advance, and then supplied from the first chute of a vented twin-screw ruder to form pellets. A commonly used method is appropriately used. The composition thus obtained is injection-molded,
It can be easily molded by any method such as extrusion molding, compression molding, or rotational molding, and an optical functional sheet having good characteristics can be obtained.

[0018]

The present invention will be described below with reference to examples. In addition, the evaluation in an Example was implemented as follows.

(1) Total light transmittance: Measured according to ASTM D-1003 using a reflection / transmittance meter (HR-100) manufactured by Murakami Color Research Laboratory as a measuring instrument. As a test piece, a molded product of 45 mm × 50 mm × 2 mm was used.

(2) Glass transition temperature: The pellets obtained under the following conditions were measured using a thermal analyzer 2200 manufactured by TA Instruments.

(3) Evaluation of transferability: The surface of a 200 μm film obtained under the following conditions was observed with an electron microscope, and the transferability of surface irregularities was evaluated according to the following. ：: good transferability ×: poor transferability

(4) Evaluation of hue change: measured using the evaluation apparatus shown in FIGS. That is, 150 mm on a side, thickness 2
150 mm on a side, thickness 4
A 200 μm film obtained under the following conditions is superimposed on an acrylic light guide plate having a thickness of 200 mm, and a cold cathode tube having a diameter of 2.6 mm and a length of 150 mm is provided on one side of the light guide plate. The hue at 9 points on the film surface after irradiation for 2,000 hours was measured with a color luminance meter BM-7 manufactured by Topcon Co., Ltd.
The difference between the average values of the b values over time was defined as the hue change.

[Examples 1 to 3 and Comparative Examples 1 to 5] (A)
A polycarbonate resin, (B) polycaprolactone and (C) an ultraviolet absorber (D) a blue dye are blended in the proportions shown in Table 1, and a vented twin-screw extruder with a screw diameter of 30 mmφ [TEX- manufactured by Nippon Steel Works Co., Ltd.] 30XSST] at a cylinder temperature of 270 ° C and pelletized by strand cutting. The glass transition temperature was measured using the obtained pellet. The pellets obtained were further dried at 120 ° C. for 5 hours by a hot air circulating dryer, and then subjected to an injection molding machine [SG-150U manufactured by Sumitomo Heavy Industries, Ltd.] at a cylinder temperature of 280 ° C. and a mold temperature of 80 ° C. Injection molding was performed to form a plate-shaped test piece of 45 mm × 50 mm × 2 mm. Using this test piece, the total light transmittance was evaluated, and the results are shown in Table 1.

Further, the pellets obtained above are subjected to a twin screw extruder HYPER KTX manufactured by Kobe Steel, equipped with a T die.
The anti-melted sheet extruded at -30XHT was pressed against a roll having a sawtooth pattern to obtain a target optically functional sheet. The transferability was evaluated using this sheet.

The components used in Examples and Comparative Examples shown in Table 1 are as follows. (A) PC; polycarbonate resin having a viscosity average molecular weight of 22,400 [manufactured by Teijin Chemicals Ltd.] (B) Polycaprolactone; polycaprolactone Placel H-1 (manufactured by Daicel Chemical Industries, Ltd.) (C) UV absorber; ADK STAB LA-31 manufactured by Asahi Denka Kogyo Co., Ltd.

[0026]

[Table 1]

[0027]

As is evident from Table 1, the composition of the present invention exhibits excellent transparency and transferability not found in conventional optical functional sheet materials, so that OA such as personal computers can be used. As an optical functional sheet such as a light reflection sheet, a prism sheet, and a diffusion sheet for equipment and electronic equipment, it is particularly useful for a prism sheet and extremely useful industrially.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of an evaluation device of the present invention.

FIG. 2 is a schematic cross-sectional view of the evaluation device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source (cold-cathode tube) 2 Light guide plate 3 White reflective resin plate 4-12 Measurement points 13 Test pieces

Claims (3)

[Claims] (A) Aromatic polycarbonate resin 95
85% by weight (component A), (B) polycaprolactone 5
100 parts by weight of a resin composition comprising -15 to 15% by weight (component B) and (C) a benzotriazole-based ultraviolet absorber 0.0
A composition comprising 1 to 2.0 parts by weight (component C),
The glass transition temperature of the composition is 100 to 130 ° C.,
And a composition for an optical functional sheet having a total light transmittance of 90% or more in a molded product having a thickness of 2 mm. 2. The composition for an optical functional sheet according to claim 1, wherein the amount of the benzotriazole-based ultraviolet absorber is 0.01 to 1.0 part by weight. 3. A prism sheet formed from the composition for an optical functional sheet according to claim 1.