JP2907410B2 - Stretched film or sheet of polycarbonate resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film or sheet suitable for optical applications such as a protective film or sheet for a polarizing plate support plate, an optical recording medium such as an optical disk, or a reflector substrate.

[0002]

2. Description of the Related Art A polarizing plate used in an LCD (Liquid Crystal Display) cannot be put to practical use, such as durability, with a polarizing film alone. Therefore, a transparent synthetic resin film or sheet is adhered on one or both sides for protection. It has a structure.
As a protective film or sheet called a polarizing plate support plate, a transparent film or sheet of a cellulose triacetate resin (hereinafter abbreviated as TAC) has conventionally been used.

However, since the TAC film or sheet has high moisture permeability, protection against deterioration of the polarizing film due to permeated moisture is not satisfactory, and there is a problem that the polarizing plate decolorizes under high temperature and high humidity conditions. With the expansion of the use environment of LCDs, such as the incorporation of LCDs into vehicles, there has been a demand for a polarizing plate support plate with low moisture permeability.

As a polarizing plate support plate, a stretched film or sheet of acrylic resin having excellent transparency, and ethylene-
A film obtained by casting a saponified vinyl acetate copolymer has been proposed, but a stretched film or sheet of an acrylic resin has a drawback in that the heat resistance itself is poor,
Films of saponified ethylene-vinyl acetate copolymer are inferior in transparency, and have disadvantages such as limited production method to casting method and environmental problems such as solvent recovery. No. 55-155307, Tokuhei 3-23881).

[0005] Bisphenol A-based polycarbonate resin films or sheets are also transparent films or sheets, but have relatively low hygroscopicity, but surprisingly high moisture permeability, and the effect of improving the durability of the polarizing plate is sufficient. In addition, since the birefringence is large, there is a problem that the LCD characteristics are adversely affected.

Attempts have also been made to use a transparent film or sheet to prevent the recording surface of an optical recording medium such as an optical disc from being damaged. However, TAC is not applicable because it is wrinkled due to moisture absorption. At present, there is no suitable sheet.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, that is, there is little change in moisture permeability and dimensional change in moisture absorption, and transparency, weather (light) resistance, birefringence, etc. By providing a film or sheet suitable for optical applications such as a polarizing plate support plate, a protective film or sheet of an optical recording medium such as an optical disk, or a reflector substrate, which has excellent optical properties and heat resistance, and has little coloring. is there.

[0008]

The present inventors have made intensive studies on solving the above problems, and as a result, surprisingly, a stretched film or sheet made of a certain alicyclic polycarbonate resin has a moisture permeability and a moisture absorption size. The present inventors have found that they have a small change, are excellent in optical properties such as transparency, weather (light) resistance, birefringence, etc., heat resistance and mechanical properties, and have completed the present invention.

[0009] An object of the present invention is composed of repeating units represented by the following general formula [1] to [3], one
The repeating unit represented by the general formula [1] (hereinafter referred to as “general formula
The repeating unit represented by [m] is abbreviated as the unit [m].
In some cases ) is substantially equal to the total mole fraction (y + z) of the mole fraction (y) of the unit [2] and the mole fraction (z) of the unit [3]. The mole fraction (y) of [2] is in the range of 20 mol% to 50 mol%, and the stretched film or sheet made of an alicyclic polycarbonate resin having a number average molecular weight of 10,000 to 200,000 is used. Achieved.

[0010]

Embedded image However, in the general formula [1], n is 0, 1 or 2, and in the general formula [3], A is a divalent saturated aliphatic hydrocarbon group having 20 or less carbon atoms, a saturated alicyclic hydrocarbon. Or an aromatic hydrocarbon group.

The content (x) of the structural unit of the general formula [1] is substantially 50 mol%. The content (y) of the structural unit of the general formula [2] is from 20 to 50 mol%, preferably from 3 to
0 to 50 mol%. If the content is less than 20 mol%, the moisture permeability and the dimensional change in moisture absorption tend to increase, which is not preferable. The content (z) of the structural unit of the general formula [3] is basically 50-y mol%.

The structural unit represented by the general formula [1] is specifically as follows, and when the structural unit is a repeating unit in which n is 1 or 2, the heat resistance of the film or sheet is preferably high.

When n = 0

[0014]

Embedded image When n = 1

[0015]

Embedded image When n = 2

[0016]

Embedded image Further, specific examples of the structural unit of the general formula [3] include the following.

When A is a saturated aliphatic hydrocarbon

[0018]

Embedded image When A is a saturated alicyclic hydrocarbon

[0019]

Embedded image When A is an aromatic hydrocarbon

[0020]

Embedded image In applications requiring particularly low birefringence, such as a polarizing plate support plate, a saturated aliphatic hydrocarbon or saturated alicyclic hydrocarbon structure having low birefringence is preferably selected. In particular, when A is a saturated alicyclic hydrocarbon, the heat resistance is high,
In addition, a change in dimensional change due to moisture absorption is preferable. In applications where birefringence is not particularly problematic, an orientation birefringence is large, but an aromatic hydrocarbon structure can be selected. In this case,
For example, there is an advantage in that heat resistance is increased.

Each of the structural units represented by the general formulas [1] and [3] may be only one type or a mixture of two or more types. Further, other structural units may be included as long as the effects of the present invention are not impaired. The substitution amount is usually 10 mol% or less.

The molecular weight of the alicyclic polycarbonate resin must be in the number average molecular weight of 10,000 to 200,000 (in terms of polystyrene) , preferably 20,000.
１５０150,000. When the molecular weight is less than 10,000, the mechanical strength of the film or sheet of the present invention becomes insufficient, and when it exceeds 200,000, film formation becomes difficult.

When the content of an alkali metal, an alkaline earth metal, titanium, zinc, lead, manganese, antimony, germanium or a compound of these metals in an alicyclic polycarbonate resin is 5 ppm or less in metal element concentration, A film or sheet with less coloring can be obtained, which is particularly preferable for applications requiring low coloring. Conventionally, in the production of resins, these metals or metal compounds have been used as polymerization catalysts and used as mixed in the resin,
The present inventors have found that these metals or metal compounds cause coloration is a slightly film or sheet is present, can be improved coloration by without these mixed substantially. Such a material is used, for example, in the production of a resin,
-A new method using a boronic ester such as butylammonium as a polymerization catalyst.

The alicyclic polycarbonate resin is prepared from a corresponding raw material such as an acid, an ester thereof, an acid chloride (the structural unit represented by the general formula [2] is phosgene), an acid anhydride, a diol, an ester thereof, or an alkoxide. Can be produced by a known method (Japanese Patent Laid-Open No. 2-6951).
No. 9). Examples of the catalyst include tetraalkyl orthotitanate, zinc acetate, antimony oxide, germanium oxide, various alkoxides such as potassium-t-butoxide and sodium methoxide, alkali metals such as lithium and sodium, and lithium hydride and sodium hydride. Known catalysts such as alkali metal hydrides can be used. Also,
It can be produced by a novel method using a borate ester such as tetra-n-butylammonium tetraphenylboronate as a catalyst.

As long as the effects of the present invention are not impaired, a plasticizer, a dye / pigment, an ultraviolet absorber,
A resin modifier such as an antioxidant and a lubricant may be added, or another resin may be blended.

The film or sheet of the present invention needs to be stretched. Unstretched films or sheets have poor mechanical properties such as bending strength, tensile strength and tensile elongation.

For some applications, for example, uniaxially stretched films or sheets can be used, for example, it is sufficient to improve the mechanical properties in one direction, but biaxially stretched films or sheets are generally preferred.

The stretched film or sheet of the present invention can be produced by first preparing an unstretched film or sheet from an alicyclic polycarbonate resin and stretching the unstretched film or sheet.

The unstretched film or sheet can be produced by a known method, for example, press molding, melt extrusion molding and solution casting. As an industrial method, an extrusion method is preferable, and as the extrusion temperature, a temperature in the range of usually 180 to 350 ° C is used, and particularly, 200 to 300 ° C is preferably used.

The orientation release stress (AS) of the stretched film or sheet in the stretching direction
TM D1504, hereinafter abbreviated as ORS) is generally preferably 3 to 30 kg / cm ² , and more preferably 5 to 30 kg / cm ^2.
25 kg / cm ² is good. ORS is the internal stress caused by stretching, frozen in a stretched film or sheet.

A film or sheet having a small ORS has good heating shape stability but poor mechanical properties such as bending strength, tensile elongation and tensile strength. If the ORS is too high, the mechanical properties are good but the heating shape is stable. It becomes inferior in nature.

As the stretching method, known methods such as a roll uniaxial stretching method, a tenter uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and an inflation method can be used. The stretching temperature ranges from 10 ° C. higher than Tg of the resin to 50 ° C.
If the temperature is too high, stretching is difficult. If the temperature is too high, stretching unevenness is large. The stretching ratio is preferably 1.1 to 3.5 times, particularly preferably 1.5 to 2.5 times. If the stretching ratio is too large, the film is easily broken, and the stretching unevenness increases. The stretching speed is usually 100 to
5000% / min is used. Generally, it is cooled immediately after the completion of stretching.

The thickness of the film or sheet of the present invention is
Although not essentially limited, 10 μm to 5 μm
mm, particularly preferably 20 μm to 2 mm. If the thickness is small, it is easily broken during molding, and if it is too thick, a large stretching load is required during stretching.

[0034]

The stretched film or sheet of the present invention has low moisture permeability and small change in moisture absorption, transparency, weather resistance (light),
It is excellent in optical properties such as birefringence, heat resistance, and mechanical properties.

Low moisture permeability is a very desirable property as a support plate of a polyvinyl alcohol polarizing plate using iodine as a polarizing element, which is problematic in performance degradation caused by passing moisture. As a result, a polarizing plate with improved durability became possible.
In this application, for example, n in the general formula [1] is 1
A preferable example is a biaxially stretched film of a resin of the general formula [2] having a molar fraction of 50%. The film 100 mu moisture permeability thickness and very 4g / m ² / 24hr low, about 1/100 of the TAC being conventionally used
And the durability is greatly improved. This characteristic is that the moisture permeability of a 100 μm film of bisphenol A polycarbonate resin, which is the same polycarbonate resin, is 35%.
It was unexpected at all because of high and g / m ² / 24hr.

[0036] This application, moisture permeability 20g / m ^2/24
hr or less, is also preferably used a film or sheet, especially 15g / m ² / 24hr or less of another present invention.

The stretched film or sheet of the present invention is also excellent in dimensional stability due to moisture absorption, and can cope with a problem due to a dimensional change due to a change in humidity. For example, the protective film made of TAC as a protective film or sheet of an optical disk such as a compact disk or a laser disk have been proposed, by the environmental humidity change, into practical use for wrinkles was not optimum et al. The film or sheet of the present invention has a small change in moisture absorption dimension and a small birefringence, and is suitable for this use. Specifically, for example, n of general formula [1]
Is 1, and the biaxially stretched film of the resin represented by the general formula [2] having a mole fraction of 50% has a dimensional change of 0% when dried and left in an environment of 23 ° C. and 95% humidity for 7 days. It is preferably used as small as 01%. This value is about 1/50 of the change in the moisture absorption dimension of the TAC film, and the occurrence of wrinkles can be suppressed even under severe humidity conditions.

For this use, the dimensional change when dried and allowed to stand in an environment of 23 ° C. and 95% humidity for 7 days is 0.1% or less, more preferably 0.05% or less. The film or sheet of the present invention is also preferably used.

When used as a protective film or sheet, it is convenient to use the stretched film or sheet of the present invention in a form in which an adhesive is laminated, and as the adhesive, a transparent adhesive is selected according to the application. For example, polyurethane-based, epoxy-based, and acrylic-based materials can be used. A method is also possible in which an adhesive is laminated on the surface to be protected, and a protective film or sheet is adhered to the adhesive.

The stretched film or sheet of the present invention can withstand a temperature of 100 ° C. or more without being deformed or deteriorated, and has excellent weather (light) resistance. It can be suitably used as a reflector used on the back side of lighting for improving the efficiency of the apparatus.

The film or sheet of the present invention, which is excellent in heat resistance, moisture absorption dimensional stability, and transparency, is also preferable for uses of transparent films or sheets other than optical uses, for example, for nameplates.

In the present invention, those having a thickness of less than 254 μm are distinguished from films and those having a thickness of 254 μm or more are distinguished from sheets.

The method for measuring the characteristic values will be described below. Transparency: total light transmittance, haze (ASTM D100
3) was evaluated. -Colorimetry: Measured according to JIS K7105 (C light source,
10 ° field of view, transmission method). -Metal analysis: Analyzed by atomic absorption method. Birefringence: Observed with a strain tester SVP-10 manufactured by Toshiba Glass Co., Ltd. -Moisture absorption dimensional stability: After drying in an oven at 80 ° C for 48 hours, it was evaluated by dimensional change after leaving it in an environment of 23 ° C and 95% humidity for 7 days. -Moisture permeability: Measured according to JIS Z0208. -Number average molecular weight: Determined by GPC measurement in comparison with a standard polystyrene molecular weight (polystyrene conversion). Glass transition temperature (Tg): Measured by differential thermal analysis (in nitrogen, heating temperature 10 ° C./min). ORS: Measured according to ASTM D1504. -Tensile strength and tensile elongation: Measured according to ASTM D882-64T. -Folding strength: The object to be measured is made into a strip having a width of 15 mm.
The number of times of bending without breaking was determined by using a T-type folding fatigue tester {Bending speed 30 times / minute, manufactured by Toyo Seiki Seisaku-sho, Ltd.}.

[0044]

EXAMPLES The present invention will be specifically described with reference to examples.

Example 1 Trans-2,3-di (hydroxymethyl) -perhydro-1, 4: 5,8-dimethanonaphthalene 13.4 Kg
Using 12.9 kg of diphenyl carbonate and 0.7 g of tetra-n-butylammonium tetraphenylboronate as a catalyst, an alicyclic polycarbonate resin comprising a repeating structural unit represented by the general formula [4] was obtained by a melt condensation reaction. Obtained. The number average molecular weight of the obtained resin was 29000, and Tg was 125 ° C.

[0046]

Embedded image This resin is pressed at a temperature of 200 ° C.
An unstretched sheet of μ was produced. Using a pantograph-type biaxial stretching tester {manufactured by Toyo Seiki Co., Ltd.}, a stretching temperature of 155 ° C., a stretching speed of 1000% / minute in one direction, and a stretching direction of 2
The film was simultaneously biaxially stretched at twice the draw ratio to produce a stretched film having a thickness of 100 μm. The ORS of the biaxially stretched product was 9 kg / cm ² in both directions. The bending strength was 30 times, the tensile strength was 350 kg / cm ² , and the tensile elongation was 2.0%, which was excellent in mechanical strength, and had sufficient strength for handling.

The metal of this film was analyzed by atomic absorption spectroscopy. Alkali metal, alkaline earth metal, titanium, zinc,
The contents of all elements of lead, manganese, antimony and germanium were 1 ppm or less.

Total light transmittance 93%, haze 0.3%
The colorimetric values of L * are 96.42 and a * is-
It was a colorless film excellent in transparency, with little coloration, 0.01 and b * of 0.17. The moisture permeability is 4
g / m ² / 24hr as low, after drying, 23 ° C., 95
% For 7 days, but the dimensional change is 0.01%
% And small.

When a film was placed between a pair of orthogonal polarizing plates using a strain tester and rotated, the brightness and hue of the orthogonal polarizing plates did not change, and no birefringence was observed. Further, the sample was heated to 115 ° C., but no deformation was observed.

This film was adhered to both surfaces of a polyvinyl alcohol polarizing film using iodine having a thickness of 30 μm as a polarizing element with a urethane adhesive to produce a polarizing plate. The polarizing plate was excellent in polarizing performance with two parallel transmittances of 40% and a degree of polarization of 99.9% or more. A durability test was carried out under the conditions of 80 ° C. and 90% humidity, but even after 350 hours, the parallel transmittance was 45% and the degree of polarization was 98.9%, which was a slight change.

Comparative Example 1 An 80 μm triacetate film (FT-8, manufactured by Fuji Photo Film Co., Ltd.) used as a support plate for a polarizing plate
The moisture permeability of 0) was 480g / m ² / 24hr. Using this as a support plate, a polarizing plate was produced in the same manner as in Example 1,
A durability test was performed under the conditions of 80 ° C. and 90% humidity. The initial polarization performance was such that the parallel transmittance of two sheets was 41% and the degree of polarization was 99.
It was 9% or more, but after 100 hours, the two sheets had a parallel transmittance of 51% and a degree of polarization of 75.3%, making them unsuitable for use as a polarizing plate.

Comparative Example 2 In the same manner as in Example 1, 150
An unstretched film of μ was produced. The bending strength is broken by the first bending, and the tensile strength is 200 kg / c.
The film was inferior in mechanical strength with m ² and tensile elongation of 0.9%.

Example 2 In Example 1, trans-2,3-di (hydroxymethyl) -perhydro-1, 4: 5,8-dimethanonaphthalene was replaced by 13.4 kg of trans-2,3-di ( (Hydroxymethyl) -perhydro-1, 4: 5, 10:
An alicyclic polycarbonate resin comprising a repeating structural unit represented by the general formula [5], having a number average molecular weight of 69000 and a Tg of 160 ° C. is obtained by the same method except that 17.4 kg of 6,9-trimethanoanthracene is used. Manufactured.

[0054]

Embedded image An unstretched sheet of about 500 μ was produced from this resin by extrusion molding. Using a pantograph-type biaxial stretching tester (manufactured by Toyo Seiki Co., Ltd.), simultaneous biaxial stretching was performed at a stretching temperature of 190 ° C., a stretching speed of 1000% / minute in one direction, and a stretching ratio of 2.2 times in one direction. The film was stretched to produce a stretched film having a thickness of 105 μm. The ORS of this biaxially stretched product is 12K in both directions.
g / cm ² . Folding strength 26 times, tensile strength 4
This film, which had an excellent mechanical strength of 20 Kg / cm ² and a tensile elongation of 2.8%, was subjected to metal analysis by atomic absorption spectroscopy. The alkali metal, alkaline earth metal, titanium, zinc,
The contents of all elements of lead, manganese, antimony and germanium were 1 ppm or less.

Total light transmittance 93%, haze 0.3%
The colorimetric values are as follows: L * is 96.24, a * is-
0.02 and b * of 0.29, indicating that the film was a colorless film having excellent transparency with almost no coloring. Moisture permeability 3
g / m ² / 24hr and was low. After drying, 23
It was left in an environment at a temperature of 95 ° C and a humidity of 95% for 7 days, but the dimensional change was as small as 0.01%.

No birefringence was observed, and the sample was heated to 150 ° C., but no deformation was observed.

An adhesive was partially applied to this film so that only the inner and outer peripheral portions of the laser disk were stuck.
Affixed to laser disk. The humidity was changed from 10% to 95% at 25 ° C., but no wrinkling occurred. The laser disk was reproduced with the protective film attached, but no abnormality was found.

Comparative Example 3 An 80 μm triacetylcellulose resin film (Fujitac, FT-80, manufactured by Fuji Photo Film Co., Ltd.) was dried and then left in an environment of 23 ° C. and 95% humidity for 7 days. Was 0.6%.

This film was adhered to a laser disk in the same manner as in Example 2, and the humidity was 10% at 25 ° C.
When it was changed from 95% to 95%, wrinkles occurred and reproduction became impossible.

Example 3 In Example 1, trans-2,3-di () was replaced with 13.4 kg of trans-2,3-di (hydroxymethyl) -perhydro-1, 4: 5,8-dimethanonaphthalene. (Hydroxymethyl) -perhydro-1, 4: 5,8-dimethanonaphthalene 6.7 kg and trans-2,3-di (hydroxymethyl) bicyclo [2.2.1] heptane 4.7 kg It comprises a structural unit represented by the general formula [6] and has a number average molecular weight of 4
An alicyclic polycarbonate resin having a Tg of 8000 and a Tg of 118 ° C. was produced.

[0061]

Embedded image An unstretched sheet of about 900 μm was prepared from this resin by extrusion molding. Using a pantograph-type biaxial stretching tester {manufactured by Toyo Seiki Co., Ltd.}, simultaneous biaxial stretching was performed at a stretching temperature of 140 ° C., a stretching speed of 500% / minute in one direction, and a stretching ratio of 1.75 times in one direction. The sheet was stretched to produce a stretched sheet having a thickness of 300 μm. The ORS of this biaxially stretched product is 11 kg / in both directions.
cm ² and excellent mechanical strength.

The metal of this sheet was analyzed by atomic absorption spectroscopy. As a result, alkali metal, alkaline earth metal, titanium, zinc,
The contents of all elements of lead, manganese, antimony and germanium were 1 ppm or less.

Total light transmittance 93%, haze 0.4%
The colorimetric values of L * are 96.39 and a * is-
The colorless sheet was excellent in transparency, with little coloration of 0.02 and b * of 0.23. After drying, 23
It was left in an environment at a temperature of 95 ° C. and a humidity of 95% for 7 days, but the dimensional change was as small as 0.02%. No birefringence was observed, and heating to 100 ° C. showed no deformation.

Example 4 trans-2,3-di (hydroxymethyl) -perhydro-1, 4: 5,8-dimethanonaphthalene 13.4K
g, 9.0 kg of diphenyl carbonate, 3.5 kg of diphenyl terephthalate, and 0.5 g of lithium hydride as a catalyst, using the same method as in Example 1 to obtain a compound represented by the general formula [7]. Has a number average molecular weight of 4
An alicyclic polycarbonate resin having 3000 and Tg of 137 ° C. was produced.

[0065]

Embedded image From this resin, an unstretched sheet of about 200 μ was produced by extrusion molding. Using a pantograph-type biaxial stretching tester (manufactured by Toyo Seiki Co., Ltd.), the film was successively biaxially stretched at a stretching temperature of 165 ° C., a stretching speed of 500% / minute in one direction, and a stretching ratio of 1.75 times in one direction. The film was stretched to prepare a stretched film having a thickness of 65 μm. The ORS of this biaxially stretched product was 9 kg / cm ² in the direction of first stretching, and 12 kg / cm ² in the direction of later stretching.
^{Was 2} . The bending strength was excellent 55 times when it was bent along the direction in which it was initially stretched, and 39 times when it was bent in the direction in which it was stretched later.

Total light transmittance 92%, haze 0.4%
The film was excellent in transparency and was heated to 125 ° C., but no deformation was observed.

[0067]

According to the present invention, a film or sheet of a polycarbonate resin having an alicyclic structural unit has a small change in moisture permeability and moisture absorption dimensions, and is excellent in optical properties such as transparency, weather resistance (light) and birefringence, and heat resistance. A film or sheet excellent in mechanical properties and suitable for optical use can be obtained. This film or sheet is suitable for use as, for example, a polarizing plate support plate, a protective film or sheet for an optical recording medium such as an optical disk, or a substrate for a reflector.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification code FI // B29K 69:00 B29L 7:00 (58) Field surveyed (Int.Cl. ⁶ , DB name) C08J 5/00-5 / 02 C08J 5/12-5/22 B29C 55/00-55/30

Claims (4)

(57) [Claims] 1. A repeating unit represented by the following general formula [1] , comprising repeating units represented by the following general formulas [1] to [3] :
The unit molar fraction (x) is a repeating unit represented by the general formula [2].
Unit mole fraction (y) and repetition represented by general formula [3]
Total mole fraction of the mole fraction of units (z) (y + z) is substantially equal, the formula the molar fraction of the repeating unit represented by [2] (y) is 50 mol% or less than 20 mol% A stretched film or sheet comprising an alicyclic polycarbonate-based resin having a number average molecular weight of 10,000 to 200,000 in a range. Embedded image However, in the general formula [1], n is 0, 1 or 2, and in the general formula [3], A is a divalent saturated aliphatic hydrocarbon group having 20 or less carbon atoms, a saturated alicyclic hydrocarbon. Or an aromatic hydrocarbon group. 2. The stretched film or sheet according to claim 1, wherein the film or sheet is a biaxially stretched film or sheet. 3. An orientation release stress in a stretching direction in a range of 3 to 30 kg / cm ² .
3. The stretched film or sheet according to 2. 4. The content of an alkali metal, an alkaline earth metal, titanium, zinc, lead, manganese, antimony, germanium or a compound of these metals in an alicyclic polycarbonate resin is 5 ppm or less in a metal element concentration. The stretched film or sheet according to any one of claims 1 to 3.