JP2000143961A - Polycarbonate resin composition for sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polycarbonate resin composition for sheets holding characteristic weather resistance and mechanical properties, at the same time, capable of reducing the adherend and dirt formed at the die lip of an extruder while the composition is formed into sheets in an extruding processing and useful as a building material or the like by compounding a specific amount of a specific internal mold release agent in the composition. SOLUTION: The objective composition consists of (A) 100 pts.wt. of a polycarbonate resin, (B) 0.1-0.3 pt.wt. of an ultraviolet absorber, (C) 0.005-0.07 pt.wt. of an internal mold release agent whose 90 wt.% or more consists of the ester of a monohydric alcohol and a monocarboxylic aliphatic acid and/or the full ester of a polyhydric alcohol and an aliphatic acid, and (D) 0.01-0.05 pt.wt. of a phosphorus-containing stabilizer [e.g. tris(2,4-di-tert-butylphenyl) phosphite] whose 90 wt.% or more is one or more kinds selected from the group of compounds of formula I to formula III (R1 to R6 are each a 1-10C alkyl).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin composition for a sheet capable of reducing stains on a die lip of an extruder when a weather-resistant polycarbonate resin sheet is produced by extrusion.

[0002]

2. Description of the Related Art Polycarbonate resin sheets have attracted attention as substitutes for glass because of their excellent transparency and impact resistance, and are used in many fields including building materials.

[0003] Polycarbonate resins are relatively high in weather resistance among polymer materials, but when exposed to ultraviolet rays for a long period of time, for example, when used outdoors, they become transparent due to yellowing and cracks on the surface. Properties and mechanical properties are also reduced. An effective method for suppressing such deterioration of the resin due to ultraviolet rays, that is, for imparting weather resistance, is a method of blending an ultraviolet absorber, which is widely applied to sheet materials. The effective amount of UV absorbers is generally higher than other additives, and as a result, the proportion of additives incorporated in the weather-resistant polycarbonate resin composition is high, and correspondingly the volatilization during processing Many minutes.

Conventionally, when a polycarbonate resin composition (powder or pellet) imparted with weather resistance is extruded into a sheet, there has been a problem that the periphery of the die lip is easily stained. Dirt around the die lip is directly linked to surface defects such as die lines (vertical streaks in the extrusion direction) and dirt on the sheet.

[0005] To solve this problem, it is effective to periodically clean the vicinity of the die lip. However, it is necessary to stop the operation in order to safely perform sufficient cleaning, and the production efficiency is reduced. In order to solve this problem, there is an idea of reducing volatile components during extrusion. Examples of the volatile components include compounded various additives, additive decomposition products, and resin decomposition products.

[0006] Most of the resin decomposed products are generated by heat during processing, and when the blending amount of an ultraviolet absorber or a release agent exceeds a certain amount, the resin decomposed products tend to increase due to the influence thereof. is there. In many materials having sufficient weather resistance, the amount of each compounding additive used is the highest for the weathering agent, so that the effect of the weathering agent on volatile matter is very large.

Therefore, as one method of solving the problem, there is a method of reducing the amount of a weathering agent (ultraviolet absorber) in order to reduce the amount of volatile substances to such an extent that the die lip is not stained. Unfortunately, however, this method cannot provide sufficient weather resistance.

Another method is to use a weathering agent having a high molecular weight and a low volatility. However, in reality, dirt near the die lip cannot be reduced by that method. In other words, when a weathering agent having a high molecular weight and a low volatility is used, the volatilization amount of the weathering agent is reduced to some extent, but volatilization cannot be completely suppressed. Generation cannot be suppressed. Moreover, the weathering agent once volatilized is more likely to condense around the die lip than a weathering agent having a low molecular weight and a high volatility.

That is, when extruding a weather-resistant polycarbonate resin composition into a sheet,
No effective means has been found to reduce the deposit contamination around the die lip.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet having a reduced amount of stain on a die lip of an extruder while maintaining an effective amount of a weathering agent when producing a weatherable polycarbonate sheet. It is to provide a polycarbonate resin composition for use.

[0011]

Means for Solving the Problems As a result of intensive studies to achieve the object, we have found that in a polycarbonate resin composition for a sheet having weather resistance, a specific internal mold release compounded in the resin composition is used. The combination of a specific amount of a specific phosphorus-based stabilizer and a specific amount of a phosphorus-based stabilizer is the same as “the weather-resistant polycarbonate resin composition is extruded into a sheet while maintaining the original weather resistance and mechanical properties. To reduce deposits and stains on the die lip of the extruder when forming.

It is natural to think that the use of the release agent is disadvantageous for solving the problem because it leads to increase of volatile components.
“Use of a specific internal release agent” can surprisingly be an effective factor in achieving the task.

That is, the object of the present invention is to provide (A) 100 parts by weight of a polycarbonate resin, and (B) an ultraviolet absorbent.
1 to 0.3 parts by weight, (C) 90% by weight or more of an internal release agent comprising an ester of a monohydric alcohol and a monohydric fatty acid and / or a full ester of a polyhydric alcohol and a fatty acid 0.0
0.5 to 0.07 parts by weight and 90% by weight or more of (D) one or more phosphorus-based stabilizers selected from the group of compounds represented by the following formulas (1), (2) and (3). 01 ~
A polycarbonate resin composition for a sheet comprising 0.05 parts by weight.

[0014]

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[0015]

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[0016]

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(Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are alkyl groups having 1 to 10 carbon atoms)

The compounding amount of the ultraviolet absorber used in the present invention is 0.1 to 100 parts by weight of the polycarbonate resin.
To 0.3 parts by weight, preferably 0.15 to 0.28
Parts by weight. If the amount is too small, there is a problem that sufficient weather resistance cannot be imparted to the obtained polycarbonate resin sheet. If the compounding amount is too large, the effect of the ultraviolet absorber "the stain on the die lip during the extrusion to the sheet" is less than the effect of "the reduction of the stain and the deposit on the die lip during the extrusion to the sheet" of the present invention. And increase in attached matter ".

The ultraviolet absorber compound used in the present invention is, specifically, benzophenone-based compounds such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, -Hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxybenzophenone, 2-hydroxy-4-methoxy-
5-sulfoxytrihydridobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4 '
-Dimethoxy-5-sodiumsulfoxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2-hydroxy-4-n-dodecyloxybensophenone, 2-hydroxy-4-methoxy- 2'-carboxybenzophenone and the like;
In the benzotriazole series, 2- (2-hydroxy-5
-Methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dicumylphenyl) phenylbenzotriazole, 2- (2- Hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazole -2-yl) phenol], 2- (2-hydroxy-3,5-di-te
rt-butylphenyl) benzotriazole, 2- (2
-Hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, 2- (2-hydroxy- 5-ter
t-octylphenyl) benzotriazole, 2- (2
-Hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-4-octoxyphenyl) benzotriazole, 2,2'-methylenebis (4-cumyl-6-benzotriazolephenyl),
2,2′-p-phenylenebis (1,3-benzoxazin-4-one), 2- [2-hydroxy-3- (3,
4,5,6-tetrahydrophthalimidomethyl) -5
[Methylphenyl] benzotriazole, which can be used alone or as a mixture of two or more. Preferably, 2- (2-hydroxy-5-tert)
-Octylphenyl) benzotriazole, 2- (2-
Hydroxy-3,5-dicumylphenyl) phenylbenzotriazole, 2- (2-hydroxy-3-tert)
-Butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2'-methylenebis [4- (1,1,
3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol].

The amount of the internal release agent used in the present invention is as follows:
0.005 to 100 parts by weight of polycarbonate resin
To 0.07 parts by weight, preferably 0.01 to 0.07 parts by weight.
6. If the compounding amount of the internal release agent is too large, the effect of reducing stains and deposits on the die lip in the present invention,
The object of the present invention cannot be achieved because priority is given to the effect of increasing dirt and attached matter on the die lip due to volatilization of the internal release agent itself.

The internal release agent used in the present invention means an internal release agent used in an injection molding material.
At least 0% by weight is an internal release agent composed of an ester of a monohydric alcohol and a monohydric fatty acid and / or a full ester of a polyhydric alcohol and a fatty acid.

The object of the present invention cannot be achieved if free fatty acids, free alcohols, or partial esters of polyhydric alcohols are present in the internal release agent blended in the present invention.

The higher fatty acid full ester of a monohydric or polyhydric alcohol, which is an internal release agent used in the present invention, comprises a monohydric or polyhydric alcohol having 1 to 20 carbon atoms and a monohydric or polyhydric alcohol having 5 to 30 carbon atoms. Preferably, it is a full ester with a saturated fatty acid. Such full esters of monohydric or polyhydric alcohols with saturated fatty acids include stearyl stearate, palmityl palmitate, butyl stearate, methyl laurate, isopropyl palmitate,
-Ethylhexyl stearate, stearic acid triglyceride, sorbitan distearate, pentaerythritol tetrastearate, pentaerythritol tetraperargonate, propylene glycol distearate and the like, and these can be used alone or in a mixture of two or more. Of these, stearic acid triglyceride, stearyl stearate, and pentaerythritol tetrastearate are preferably used.

At least 90% by weight of the phosphorus stabilizer used in the present invention is a phosphorus stabilizer selected from the group of compounds represented by the following general formulas (1), (2) and (3). Can be used alone or as a mixture of two or more. More preferred among the phosphorus-based stabilizers are those in which R ₁ , R ₂ , R ₃ and R _{4 in} formulas (1) and (2) are all t.
An tert-butyl group, R ₅ in the general formula (3) is a tert-butyl group, and R ₆ is a methyl group.

[0025]

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[0026]

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[0027]

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(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are alkyl groups having 1 to 10 carbon atoms.)

Specifically, tris (2,4-di-tert)
-Butylphenyl) phosphite, bis (2,6-di-
(tert-butyl-4-methylphenyl) pentaerythritol diphosphite and tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylenediphosphophosphinate. Of these, tris (2,4-di-tert-butylphenyl) phosphite is more preferred.

The amount of the phosphorus stabilizer used in the present invention is at least 90% by weight, preferably at least 95% by weight, more preferably substantially 100% by weight, based on 100% by weight of the total stabilizer.
It is. If the proportion of the stabilizer other than the compounds represented by the general formulas (1), (2) and (3) increases, the object of the present invention cannot be achieved.

The amount of the phosphorus stabilizer used in the present invention is 0.01 to 100 parts by weight of the polycarbonate resin.
To 0.05 part by weight, preferably 0.015 to 0.5 part by weight.
04 parts by weight.

If the amount is too small, there is a problem that the molecular weight is lowered and the hue is deteriorated at the time of extrusion into a sheet. If the compounding amount is too large, the effect of increasing the stains and deposits on the die lip due to the effect of the phosphorus-based stabilizer takes precedence over the effect of reducing the stains and deposits on the die lip, which is a feature of the present invention. Or, the object of the present invention cannot be achieved.

It is preferable to blend a bluing agent into the polycarbonate resin composition for a sheet of the present invention as long as the object of the present invention is not impaired. The bluing agent is effective for eliminating the yellow tint of the sheet product. In particular, in the case of a composition imparted with weather resistance, a certain amount of an ultraviolet absorber is blended, so that there is a reality that the sheet product tends to take on a yellow tint due to the "action and color of the ultraviolet absorber", and the sheet product is naturally used. The blending of a bluing agent is very effective for imparting an excellent transparency.

The blending amount of the bluing agent in the present invention is 0.05 to 1.5 ppm of the whole resin composition,
Preferably, it is 0.1 to 1.2 ppm. If the amount is too large, the bluish tint of the sheet product becomes strong and the luminous transparency decreases. If the amount is too small, the effect of the bluing agent that reduces the yellow color and imparts a natural transparency is not exhibited.

Specific examples of bluing agents include, for example, Solvent Violet 13 [CA. No
(Color index No.) 60725; Trade name “Macrolex Violet B” manufactured by Bayer, “Diaresin Blue G” manufactured by Mitsubishi Chemical Corporation, “Sumiplast Violet B” manufactured by Sumitomo Chemical Co., Ltd.], generic name S
solvent Violet 31 [CA. No 682
10; trade name “Diaresin Violet D” manufactured by Mitsubishi Chemical Corporation], generic name Solvent Violet 3
3 [CA. No. 60725; Trade name: Mitsubishi Chemical Corporation
"Diaresin Blue J"], generic name Solvent
Blue 94 [CA. No 61500; Trade name “Diaresin Blue N” manufactured by Mitsubishi Chemical Corporation], generic name S
solventViolet36 [CA. No 6821
0; brand name “Macrolex Violet 3R” manufactured by Bayer AG], generic name Solvent Blue 97 [brand name “Macrolex Blue RR” manufactured by Bayer AG] and generic name Solvent Blue 45 [CA. No 6
1110; Trade name "Tetazole Blue R" manufactured by Sando
LS "], Macrolex Violet and Triazo-ruble-RLS of Ciba Specialty Chemicals, etc., and Macrolex Violet and Triazo-ruble-RLS are particularly preferred.

The molecular weight of the polycarbonate resin of the present invention is 19,000-45,000 in terms of viscosity average molecular weight (M).
0 is preferable, and 21,000 to 35,000 is more preferable. An aromatic polycarbonate resin having such a viscosity average molecular weight is preferable because it maintains good fluidity during extrusion processing and at the same time has a certain mechanical strength with respect to the obtained sheet. When the molecular weight is less than 19,000, a practical material cannot be obtained because the strength of the sheet product is not high, and when the molecular weight exceeds 45,000, there arises a problem that the fluidity in extrusion into a sheet is poor. .

In the present invention, the viscosity average molecular weight is such that 0.7 g of an aromatic polycarbonate resin is added to 100 ml of methylene chloride.
Is measured at 20 ° C. using a specific viscosity (η
_SP ) in the following equation. η _SP /c=[η]+0.45×[η] ² c (where [η]
Is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7

The aromatic polycarbonate resin used in the present invention is obtained by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method. Representative examples of the dihydric phenol used here include:
2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A), bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl)
Ethane, 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) ether, 4,4
-Dihydroxydiphenyl, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like. Preferred dihydric phenols are bis (4-hydroxyphenyl) alkanes, of which bisphenol A is particularly preferred.

As the carbonate precursor, carbonyl halide, carbonate ester, haloformate and the like are used, and specific examples include phosgene, diphenyl carbonate and dihaloformate of dihydric phenol.

In producing the aromatic polycarbonate resin by reacting the dihydric phenol with the carbonate precursor by a solution method or a melting method, the dihydric phenol may be used alone or in combination of two or more. A catalyst, a terminal terminator, an antioxidant for dihydric phenol, and the like may be used according to the requirements. Further, the aromatic polycarbonate resin may be a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound, and may be aromatic or aliphatic, preferably aromatic or aliphatic difunctional having 8 or more carbon atoms. It may be a polyester carbonate resin obtained by copolymerizing a hydrophilic carboxylic acid, or a mixture of two or more aromatic polycarbonate resins.

The reaction by the solution method is usually a reaction between dihydric phenol and phosgene, and is carried out in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine or triethylamine is used. As the organic solvent, for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. For promoting the reaction, a catalyst such as a tertiary amine or a quaternary ammonium salt can be used. At that time, the reaction temperature is usually 0 to 40 ° C., and the reaction time is several minutes to 5 hours.

The reaction by the melting method is usually a transesterification reaction between dihydric phenol and diphenyl carbonate. The dihydric phenol and diphenyl carbonate are mixed in the presence of an inert gas, and the reaction is carried out under reduced pressure, usually at 120 to 350 ° C. Let it. The degree of decompression is changed step by step,
The phenols produced at a pressure of not more than mmHg are removed outside the system. The reaction time is usually about 1 to 4 hours.

In the polymerization reaction, monofunctional phenols can be used as a terminal stopper. For reactions using phosgene as a carbonate precursor,
Monofunctional phenols are commonly used as molecular terminators for molecular weight control, and the resulting polycarbonate resins are capped by groups based on monofunctional phenols, so that Excellent heat stability. Similarly, in the case of a transesterification reaction using diphenyl carbonate as a carbonate precursor, it can be preferably used for improving thermal stability. The monofunctional phenol may be any one used as a terminal terminator for polycarbonate, and is generally a phenol or a lower alkyl-substituted phenol, and is a monofunctional phenol represented by the following general formula (4). Can be shown.

[0044]

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(Wherein R is a hydrogen atom or carbon number 1-9,
It preferably represents an alkyl group of 1 to 8, and m represents an integer of 1 to 5, preferably 1 to 3. )

Specific examples of the monofunctional phenols include, for example, phenol, p-tert-butylphenol, p-cumylphenol and isooctylphenol.

The polycarbonate resin composition for a sheet of the present invention may be a blend of a polycarbonate resin powder and various additives, or may be a pellet obtained by extruding it. Good. When the former is used, pelletization can be omitted and the manufacturing process can be shortened in the sense of directly extruding the powdery blend into a sheet. When the latter is used, in the sense that the pellets have stable extrusion performance, stable operation can be performed with less operation trouble when extruding into a sheet, and the quality of the sheet is easily stabilized.

For blending the additives in the aromatic polycarbonate resin of the present invention, any method is employed. For example, a method of mixing with a tumbler, a V-type blender, a super mixer, a Nauta mixer, a Banbury mixer, a kneading roll, an extruder or the like is appropriately used.
The aromatic polycarbonate resin thus obtained is extruded into a sheet as it is or once into a pellet by a melt extruder.

The blending of the additives may be carried out in one stage, or may be carried out in two or more stages. In a method carried out in two stages, for example, after blending a part of the polycarbonate resin powder to be blended with the blending additive, that is, diluting the blending additive with the polycarbonate resin powder and then adding the master powder of the additive. After that, there is a method of performing a final blending using this.

[0050]

The present invention will be further described with reference to the following examples. “Parts” in the examples are parts by weight. The evaluation was performed by the following method.

(1) Time Until Dirt Occurs When extruding a sheet, the time at which the presence of dirt (black oily deposits) can be visually confirmed for the first time at the die lip portion of the extruder is referred to as “extrusion time”. Time since start "
And (2) Weather resistance test (ΔYI) The amounts shown in Tables 1 and 2 were blended, and the resin temperature was 290.
Extruded and pelletized at ℃. The pellet was injection molded at a resin temperature of 290 ° C. to obtain a flat molded piece having a thickness of 2 mm.
This flat plate was treated for 1000 hours with a sunshine weather meter in accordance with JIS A1415. The difference in yellowness (YI) before and after the treatment was ΔYI.

Examples 1 to 10, Comparative Examples 1 to 8 and Reference Example 1 Viscosity average molecular weights shown in Table 1 obtained from bisphenol A, p-tert-butylphenol (terminal terminator) and phosgene by a conventional method. Combinations and blending amounts of a specific ultraviolet absorber, a specific phosphorus-based stabilizer, a specific internal mold release agent and a specific blueing agent with respect to 100 parts by weight of a powdery aromatic polycarbonate resin having According to the formula. The blended powder was extruded horizontally at a resin temperature of 290 ° C. to produce a sheet having a thickness of 5 mm. The film forming speed at that time was 0.5 m / min.
Extrusion The presence or absence of dirt on the die lip portion of the extruder was visually checked every hour from the start of extrusion.

As a result, the "time from the start of extrusion" in which dirt from the die lip was first confirmed was as shown in Table 1. As a reference example, a sheet without a weathering agent was also evaluated. The contents of the additive samples shown in the table are as follows.

(A) UV absorber UV absorber A: 2- (2-hydroxy-5-tert)
-Octylphenyl) benzotriazole UV absorber B: 2- (2-hydroxy-3,5-dicumylphenyl) phenylbenzotriazole UV absorber C: 2- (2-hydroxy-3-tert)
-Butyl-5-methylphenyl) -5-chlorobenzotriazole UV absorber D: 2,2'-methylenebis [4- (1,
1,3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol] (B) Internal release agent Release agent A (for comparison): glycerin monostearate Release agent B: A mixture of glycerin tristearate and stearyl stearate (the mixing ratio is about 7% by weight
0%) Release agent C: Pentaerythritol tetrastearate (C) Phosphorus stabilizer Stabilizer A (for comparison): Tris (4-n-nonylphenyl) phosphite Stabilizer B: Bis (2,6-di -Tert-butyl-4-
Methylphenyl) pentaerythritol diphosphite Stabilizer C: tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylenediphosphosphinate Stabilizer D: tris (2,4-di-tert-butyl) Phenyl) phosphite (D) bluing agent 1- (4-methylphenylamino) -4-hydroxy-
9,10-anthraquinone

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

According to the polycarbonate resin composition for a sheet provided with a certain weather resistance, the type and the amount of the phosphorus-based stabilizer are specified, and a specific fatty acid ester is used in combination to form a die lip at the time of extrusion into a sheet. It was found that it was possible to reduce the deposit stain on the part. Thereby, defects due to die marks or the like in the sheet product can be suppressed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/527 C08K 5/527

Claims (3)

[Claims] 1. (A) 100 parts by weight of a polycarbonate resin, (B) 0.1 to 0.3 parts by weight of an ultraviolet absorber, (C)
90% by weight or more of an internal release agent composed of an ester of a monohydric alcohol and a monohydric fatty acid and / or a full ester of a polyhydric alcohol and a fatty acid 0.005 to 0.07 parts by weight and (D) 90% by weight or more of the following A polycarbonate resin composition for a sheet comprising 0.01 to 0.05 parts by weight of at least one phosphorus stabilizer selected from the group of compounds represented by formulas (1), (2) and (3). Embedded image Embedded image Embedded image (Wherein, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ have 1 to 1 carbon atoms.
It is an alkyl group of 0. ) 2. R ₁ , R ₂ , and R ₃ in the general formulas (1) and (2)
R ₃ and R ₄ are both a tert-butyl group, and the general formula (3)
The polycarbonate resin composition for a sheet according to claim 1, wherein R ₅ is a tert-butyl group and R ₆ is a methyl group. 3. The polycarbonate resin composition for a sheet according to claim 1, wherein 90% by weight or more of the phosphorus-based stabilizer is a compound represented by the general formula (1).