JP2012214620A - Polycarbonate resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin sheet excellent in surface hardness and excellent in color tone.SOLUTION: The polycarbonate resin sheet has pencil hardness defined in ISO 15184 of F or larger, wherein the yellow index of 7 wt.% of a methylene chloride solution in the polycarbonate resin sheet, measured at optical length of 50 mm, is 6.8 or lower.

Description

  The present invention relates to a polycarbonate resin sheet.

Polycarbonate resins are excellent in mechanical properties such as impact resistance, heat resistance, moldability, transparency and the like, and are widely used for various mechanical parts, optical disks, automobile parts, building materials and the like.
Among these, for building materials, lightweight and transparent structural elements are required, and sheets using polycarbonate resin are often used. In this case, additional processing such as forming a multilayer sheet or applying a hard coat treatment is performed. Is often performed.

For example, Patent Document 1 reports that a polycarbonate having a 2,2-bis (4-hydroxy-3-methylphenyl) propane skeleton is used as a sheet.
Patent Document 2 reports that a polycarbonate having a cyclododecane biscresol skeleton is used as a sheet.
Patent Document 3 discloses a polycarbonate having a 2,2-bis (4-hydroxy-3-methylphenyl) propane skeleton or a polycarbonate having a 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane skeleton. A multilayer sheet in which a sheet is arranged on the surface has been reported.

Japanese Unexamined Patent Publication No. 64-69625 JP 2010-126594 A JP 2010-188719 A

However, in the conventional method, a polycarbonate resin sheet having high surface hardness and excellent color tone could not be obtained regardless of the thickness of the sheet.
Under such circumstances, an object of the present invention is to provide a polycarbonate resin sheet having excellent surface hardness and excellent color tone.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following inventions meet the above object, and have reached the present invention.

（一般式（１）中、Ｒ¹及びＲ²は、それぞれ独立に、置換若しくは無置換の炭素数１〜炭素数２０のアルキル基、又は置換若しくは無置換のアリール基を示し、Ｒ³及びＲ⁴は、それぞれ独立に、水素原子、置換若しくは無置換の炭素数１〜炭素数２０のアルキル基、又は置換若しくは無置換のアリール基を示し、Ｘは、単結合、カルボニル基、置換若しくは無置換のアルキリデン基、置換若しくは無置換の硫黄原子、又は酸素原子を示す。）
＜４＞ 前記ポリカーボネート樹脂（ａ）が、下記一般式（１ａ）〜（１ｃ）からなる群より選ばれた少なくとも１種の化合物に由来する構造単位を少なくとも含むポリカーボネート樹脂である前記＜３＞に記載のポリカーボネート樹脂シート。

＜５＞ 前記ポリカーボネート樹脂（ａ）と前記ポリカーボネート樹脂（ｂ）との重量比が、１：９９〜４５：５５の範囲である前記＜２＞乃至＜４＞のいずれかに記載のポリカーボネート樹脂シート。
＜６＞ 前記ポリカーボネート樹脂（ａ）の粘度平均分子量であるＭｖ（ａ）が、１００００以上５００００以下である前記＜２＞乃至＜５＞のいずれかに記載のポリカーボネート樹脂シート。
＜７＞ 前記ポリカーボネート樹脂（ｂ）が、下記一般式（２）で表される化合物に由来する構造単位を主として含むポリカーボネート樹脂である前記＜２＞乃至＜６＞のいずれかに記載のポリカーボネート樹脂シート。

＜８＞ ポリカーボネート樹脂シートの厚さが１μｍ〜２０００μｍである前記＜１＞乃至＜７＞のいずれかに記載のポリカーボネート樹脂シート。 The present invention relates to the inventions according to the following <1> to <8>.
<1> A polycarbonate resin sheet having a pencil hardness defined by ISO 15184 of F or higher, and a yellow index of a polycarbonate resin sheet measured by measuring a 7% by weight methylene chloride solution at an optical path length of 50 mm is 6.8 or lower. Polycarbonate resin sheet.
<2> The polycarbonate resin sheet according to <1>, wherein the polycarbonate resin sheet includes at least a polycarbonate resin (a) and a polycarbonate resin (b) having a structural unit different from the polycarbonate resin (a).
<3> The polycarbonate resin sheet according to <2>, wherein the polycarbonate resin (a) is a polycarbonate resin containing at least a structural unit derived from a compound represented by the following general formula (1).

(In General Formula (1), R ¹ and R ² each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, and R ³ and R 2 ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group, and X represents a single bond, a carbonyl group, a substituted or unsubstituted group. An alkylidene group, a substituted or unsubstituted sulfur atom, or an oxygen atom.)
<4> In the above <3>, the polycarbonate resin (a) is a polycarbonate resin containing at least a structural unit derived from at least one compound selected from the group consisting of the following general formulas (1a) to (1c). The polycarbonate resin sheet as described.

<5> The polycarbonate resin sheet according to any one of <2> to <4>, wherein a weight ratio of the polycarbonate resin (a) to the polycarbonate resin (b) is in a range of 1:99 to 45:55. .
<6> The polycarbonate resin sheet according to any one of <2> to <5>, wherein Mv (a), which is a viscosity average molecular weight of the polycarbonate resin (a), is from 10,000 to 50,000.
<7> The polycarbonate resin according to any one of <2> to <6>, wherein the polycarbonate resin (b) is a polycarbonate resin mainly including a structural unit derived from a compound represented by the following general formula (2). Sheet.

<8> The polycarbonate resin sheet according to any one of <1> to <7>, wherein the polycarbonate resin sheet has a thickness of 1 μm to 2000 μm.

  The polycarbonate resin sheet obtained by the present invention is particularly useful for electrical and electronic equipment, OA related products, automobiles, building materials, signboards / display boards, etc., because of its excellent surface hardness and good color tone.

  The present invention relates to a polycarbonate resin sheet having a pencil hardness defined by ISO 15184 of F or higher, and a yellow index measured by measuring a 7% by weight methylene chloride solution of the polycarbonate resin sheet at an optical path length of 50 mm. The present invention relates to a certain polycarbonate resin sheet.

The pencil hardness specified by ISO15184 of the polycarbonate resin sheet of the present invention is F or more, preferably H or more, more preferably 2H or more. If the pencil hardness is low, the polycarbonate resin sheet may be easily damaged when used as a product. The pencil hardness is 2B, B, HB, F, H, 2H, 3H, 4H from the lowest rank.
In addition, the yellow index of a 7% by weight methylene chloride solution of the polycarbonate resin sheet of the present invention measured at an optical path length of 50 mm is 6.8 or less, preferably 6.6 or less, more preferably 6.5 or less. is there. When the yellow index is large, the color tone is deteriorated, and the design as a sheet is poor. In particular, in a sheet that needs to be colored, the brightness is not sufficient, and the color may become dull.
In particular, the polycarbonate resin sheet of the present invention has a large portion in contact with the outside, and the hardness and color tone are highly likely to determine the superiority of product quality.

  The polycarbonate resin sheet of the present invention preferably contains at least a polycarbonate resin (a) and a polycarbonate resin (b) having a structural unit different from the polycarbonate resin (a). By including the at least two types of polycarbonate resins, the polycarbonate resin sheet may be a polycarbonate resin sheet having high surface hardness and excellent color tone.

  Hereinafter, suitable polycarbonate resins will be described as the polycarbonate resin (a) and the polycarbonate resin (b) constituting the polycarbonate resin sheet of the present invention.

（一般式（１）中、Ｒ¹及びＲ²は、それぞれ独立に、置換若しくは無置換の炭素数１〜炭素数２０のアルキル基、又は置換若しくは無置換のアリール基を示し、Ｒ³及びＲ⁴は、それぞれ独立に、水素原子、置換若しくは無置換の炭素数１〜炭素数２０のアルキル基、又は置換若しくは無置換のアリール基を示し、Ｘは、単結合、カルボニル基、置換若しくは無置換のアルキリデン基、置換若しくは無置換の硫黄原子、又は酸素原子を示す。） <Polycarbonate resin (a)>
As a polycarbonate resin (a), first, a polycarbonate resin containing at least a structural unit derived from a compound represented by the following general formula (1) is a preferred example.

(In General Formula (1), R ¹ and R ² each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, and R ³ and R 2 ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group, and X represents a single bond, a carbonyl group, a substituted or unsubstituted group. An alkylidene group, a substituted or unsubstituted sulfur atom, or an oxygen atom.)

Here, in the general formula (1), examples of the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms of R ¹ and R ² include, for example, a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. , N-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, sec-pentyl group, n-hexyl group, n-heptyl group, n-octyl group and the like. Examples of the unsubstituted aryl group include a phenyl group, a benzyl group, a tolyl group, a 4-methylphenyl group, and a naphthyl group.
Examples of the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms of R ³ and R ⁴ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -Butyl group, tert-butyl group, n-pentyl group, sec-pentyl group, n-hexyl group, n-heptyl group, n-octyl group and the like. Examples of the substituted or unsubstituted aryl group include: A phenyl group, a benzyl group, a tolyl group, 4-methylphenyl group, a naphthyl group, etc. are mentioned.
Among these, R ¹ and R ² are preferably a methyl group, an ethyl group, an n-propyl group, or a 4-methylphenyl group, and particularly preferably a methyl group. R ³ and R ⁴ are preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or a 4-methylphenyl group, and particularly preferably a hydrogen atom. Here, the bonding positions of R ¹ , R ² , R ³ and R ⁴ in the general formula (1) are arbitrarily selected from 2-position, 3-position, 5-position and 6-position with respect to X on each phenyl ring. And preferably the 3rd and 5th positions.

In the general formula (1), when X is a substituted or unsubstituted alkylidene group, it is represented by the following structural formula. Examples of the substituted or unsubstituted sulfur atom for X include —S— and —SO ₂ —.

ここで、Ｒ⁵及びＲ⁶は、それぞれ独立に、水素原子、置換若しくは無置換の炭素数１〜炭素数２０のアルキル基、又は置換若しくは無置換のアリール基を示し、ｎは正の整数を示し、Ｚは、置換若しくは無置換の炭素数４〜炭素数２０のアルキレン基又はポリメチレン基を示す。

Here, R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group, and n represents a positive integer. Z represents a substituted or unsubstituted alkylene group having 4 to 20 carbon atoms or a polymethylene group.

Examples of the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms of R ⁵ and R ⁶ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec- Examples include a butyl group, a tert-butyl group, an n-pentyl group, a sec-pentyl group, an n-hexyl group, an n-heptyl group, and an n-octyl group. Examples of the substituted or unsubstituted aryl group include phenyl Group, benzyl group, tolyl group, 4-methylphenyl group, naphthyl group and the like.
Among these, R ₅ and R ₆ are preferably a methyl group, an ethyl group, an n-propyl group, or a 4-methylphenyl group, and particularly preferably a methyl group.
Z is bonded to carbon bonded to two phenyl groups in the general formula (1) to form a substituted or unsubstituted divalent carbocycle. Examples of the divalent carbocycle include a cycloalkylidene group such as a cyclopentylidene group, a cyclohexylidene group, a cycloheptylidene group, a cyclododecylidene group or an adamantylidene group (preferably having a carbon number of 4 to Examples of the substituted group include those having these methyl substituents and ethyl substituents. Among these, a cyclohexylidene group, a methyl-substituted cyclohexylidene group, and a cyclododecylidene group are preferable.

Among the polycarbonate resins (a) including at least a structural unit derived from the compound represented by the general formula (1), at least one compound selected from the group consisting of the following general formulas (1a) to (1i) A polycarbonate resin containing the derived structural unit is preferably used.

  Among the above compounds, a polycarbonate resin containing a structural unit derived from at least one compound selected from the group consisting of the general formulas (1a) to (1c) is more preferably used.

The polycarbonate resin (a) may contain a structural unit other than the structural unit derived from the compound represented by the general formula (1) as long as the performance is not impaired.
Such a structural unit is not particularly limited. Specifically, 2,2-bis (4-hydroxyphenyl) propane (hereinafter sometimes referred to as “bisphenol A”), anhydrosugar alcohol, and the like. And structural units derived from cyclic ether compounds such as alicyclic dihydroxy compounds and spiroglycols. Among these, the structural unit derived from bisphenol A is particularly preferable.
Mv (a), which is the viscosity average molecular weight of the polycarbonate resin (a), is preferably 10,000 or more and 50,000 or less, and the upper limit is more preferably 40,000, still more preferably 35,000. The lower limit is more preferably 5,000, still more preferably 7,000. If Mv (a) is too high, the melt viscosity of the polycarbonate resin composition becomes high, and the effect of improving the surface hardness of the polycarbonate resin sheet may be reduced. On the other hand, if Mv (a) is too low, it may be difficult to mold the polycarbonate resin sheet, and cracking may occur in the polycarbonate resin sheet.

<Polycarbonate resin (b)>
Next, as the polycarbonate resin (b), a polycarbonate resin containing a structural unit derived from at least one compound selected from the group consisting of the following general formulas (2) to (13) is preferably used. A bisphenol A type polycarbonate resin mainly containing a structural unit derived from bisphenol A represented by the formula (2) is more preferably used. Here, “mainly containing structural units derived from bisphenol A” means 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, among the structural units constituting the polycarbonate resin (b). Means a structural unit derived from bisphenol A.
In addition, content of the structural unit in polycarbonate resin (b) can be calculated | required by NMR method. Specifically, it is used when synthesizing a polycarbonate resin (b), which is observed when a deuterated chloroform solution of the polycarbonate resin (b) is measured by ¹ H-NMR using a nuclear magnetic resonance apparatus (NMR apparatus). The molar composition of each structural unit can be determined by the characteristic signal area intensity ratio depending on the dihydroxy compound. The weight ratio of each structural unit is obtained from the obtained molar composition and the formula amount of each structural unit.

<Production method of polycarbonate resin>
Next, a method for producing the polycarbonate resin (a) and the polycarbonate resin (b) according to the present invention will be described. (Hereinafter, “polycarbonate resin (a) and polycarbonate resin (b)” may be collectively referred to as “polycarbonate resin”.)
The polycarbonate resin according to the present invention is obtained by polymerization using a dihydroxy compound and a carbonyl compound. Specifically, a polycarbonate resin is obtained by reacting a dihydroxy compound and carbonyl chloride (hereinafter sometimes referred to as “CDC” or “phosgene”) at the interface between an organic phase and an aqueous phase that are not arbitrarily mixed. A polycarbonate resin is produced by transesterification of a dihydroxy compound and a carbonyl compound in a molten state in the presence of a transesterification catalyst in the presence of an interfacial polycondensation method (hereinafter sometimes referred to as “interface method”). There is a melt polycondensation method (hereinafter sometimes referred to as “melting method”).
Hereinafter, each of the interface method and the melting method will be specifically described.

<Interface method>
In the production method of polycarbonate resin by the interfacial method, an aqueous alkali solution of a dihydroxy compound is usually prepared, and an interfacial polycondensation reaction between the dihydroxy compound and phosgene is performed as a condensation catalyst, for example, in the presence of an amine compound, followed by neutralization. A polycarbonate resin is obtained through water washing and drying processes. Specifically, the polycarbonate resin production process by the interfacial method includes a raw material process for preparing raw materials such as monomer components, an oligomerization process in which an oligomerization reaction is performed, a polycondensation process in which a polycondensation reaction using an oligomer is performed, A washing step for washing the reaction solution after the polycondensation reaction by alkali washing, acid washing and water washing, a polycarbonate resin isolation step for pre-concentrating the washed reaction solution and isolating the polycarbonate resin after granulation, It has at least a drying step for drying the polycarbonate resin particles. Hereinafter, each step will be described.

(Primary process)
In the primary process, the primary tank is filled with a dihydroxy compound, an aqueous solution of an alkali metal compound such as sodium hydroxide (NaOH) or an alkaline earth metal compound such as magnesium hydroxide, demineralized water (DMW), and A raw material such as an alkaline aqueous solution of a dihydroxy compound containing a reducing agent such as hydrosulfite (HS) is prepared as necessary.

(Dihydroxy compound)
Specific examples of the dihydroxy compound that is a raw material of the polycarbonate resin according to the present invention include dihydroxy compounds represented by the general formulas (1) to (13).

(Alkali metal compound or alkaline earth metal compound)
As the alkali metal compound or alkaline earth metal compound, a hydroxide is usually preferable, and examples thereof include sodium hydroxide, lithium hydroxide, potassium hydroxide, magnesium hydroxide, and calcium hydroxide. Among these, sodium hydroxide is particularly preferable.
The ratio of the alkali metal compound or alkaline earth metal compound to the dihydroxy compound is usually 1.0 to 1.5 (equivalent ratio), preferably 1.02 to 1.04 (equivalent ratio). When the ratio of the alkali metal compound or alkaline earth metal compound is excessively large or excessively small, it affects the terminal group of the carbonate oligomer obtained in the oligomerization step described later, and as a result, the polycondensation reaction tends to be abnormal. There is.

(Oligomerization process)
Next, in the oligomerization step, the alkaline aqueous solution of the dihydroxy compound and phosgene (CDC) prepared in the original preparation step are mixed in a predetermined reactor in the presence of an organic solvent such as methylene chloride (CH ₂ Cl ₂ ). A phosgenation reaction of a dihydroxy compound is performed.
Subsequently, a condensation catalyst such as triethylamine (TEA) and a chain terminator such as pt-butylphenol (pTBP) are added to the mixed solution in which the phosgenation reaction of the dihydroxy compound is performed, and the oligomerization reaction of the dihydroxy compound Is done.
Next, the oligomerization reaction liquid of the dihydroxy compound was introduced into a predetermined stationary separation tank after further oligomerization reaction, and the organic phase containing the carbonate oligomer and the aqueous phase were separated and separated. The organic phase is fed to the polycondensation process.
Here, the residence time in the oligomerization step from when the alkaline aqueous solution of the dihydroxy compound is supplied to the reactor in which the phosgenation reaction of the dihydroxy compound is performed until entering the stationary separation tank is usually 120 minutes or less, preferably 30 minutes to 60 minutes.

(phosgene)
The phosgene used in the oligomerization step is usually used in liquid or gaseous form. The preferred amount of CDC used in the oligomerization step is appropriately selected depending on the reaction conditions, particularly the reaction temperature and the concentration of the dihydroxy compound in the aqueous phase, and is not particularly limited. Usually, the amount of CDC is 1 mol to 2 mol, preferably 1.05 mol to 1.5 mol, per 1 mol of the dihydroxy compound. When the amount of CDC used is excessively large, unreacted CDC increases and the basic unit tends to be extremely deteriorated. On the other hand, if the amount of CDC used is excessively small, the amount of chloroformate group is insufficient and proper molecular weight elongation tends not to be performed.

(Organic solvent)
In the oligomerization step, an organic solvent is usually used. As the organic solvent, reaction products such as phosgene and carbonate oligomers and polycarbonate resins are dissolved at the reaction temperature and reaction pressure in the oligomerization step and are not compatible with water (or do not form a solution with water). An active organic solvent is mentioned.
Examples of such inert organic solvents include aliphatic hydrocarbons such as hexane and n-heptane; chlorinations such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane, and 1,2-dichloroethylene. Aliphatic hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene; chlorinated aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene and chlorotoluene; and other substituted aromatic hydrocarbons such as nitrobenzene and acetophenone It is done.
Among these, chlorinated hydrocarbons such as dichloromethane or chlorobenzene are preferably used. These inert organic solvents can be used alone or as a mixture with other solvents.

(Condensation catalyst)
The oligomerization reaction can be performed in the presence of a condensation catalyst. The addition timing of the condensation catalyst is preferably after CDC is consumed. The condensation catalyst can be arbitrarily selected from many condensation catalysts used in the two-phase interfacial condensation method. For example, trialkylamine, N-ethylpyrrolidone, N-ethylpiperidine, N-ethylmorpholine, N-isopropylpiperidine, N-isopropylmorpholine and the like can be mentioned. Of these, triethylamine and N-ethylpiperidine are preferable.

(Chain terminator)
In the present embodiment, monophenol is usually used as a chain terminator in the oligomerization step. Examples of monophenols include phenols; alkylphenols having 1 to 20 carbon atoms such as pt-butylphenol and p-cresol; halogenated phenols such as p-chlorophenol and 2,4,6-tribromophenol. Can be mentioned. The usage-amount of monophenol is suitably selected according to the molecular weight of the carbonate oligomer obtained, and is 0.5 mol%-10 mol% normally with respect to a dihydroxy compound.

In the interface method, the molecular weight of the polycarbonate resin is determined by the addition amount of a chain terminator such as monophenol. For this reason, from the viewpoint of controlling the molecular weight of the polycarbonate resin, the chain stopper is preferably added immediately after the consumption of the carbonate-forming compound is completed and before the molecular weight elongation starts.
When monophenol is added in the presence of a carbonate-forming compound, a large amount of condensates (diphenyl carbonates) of monophenols are produced, and it is difficult to obtain a polycarbonate resin having a target molecular weight. When the addition time of monophenol is extremely delayed, it becomes difficult to control the molecular weight, and furthermore, the resin has a specific shoulder on the low molecular weight side of the molecular weight distribution, and there is a tendency that problems such as dripping occur during molding.

(Branching agent)
In the oligomerization step, any branching agent can be used. Examples of such a branching agent include 2,4-bis (4-hydroxyphenylisopropyl) phenol, 2,6-bis (2-hydroxy-5-methylbenzyl) -4-methylphenol, 2- (4- Hydroxyphenyl) -2- (2,4-dihydroxyphenyl) propane, 1,4-bis (4,4′-dihydroxytriphenylmethyl) benzene and the like. In addition, 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and the like can also be used. Among these, a branching agent having at least three phenolic hydroxyl groups is preferable. The amount of branching agent used is appropriately selected according to the degree of branching of the carbonate oligomer obtained, and is usually 0.05 mol% to 2 mol% with respect to the dihydroxy compound.

In the oligomerization step, when the two-phase interfacial condensation method is employed, the organic phase containing the dihydroxy compound and the alkali metal compound or alkaline earth are contacted prior to the contact between the aqueous solution of the alkali metal compound or alkaline earth metal compound of the dihydroxy compound and phosgene. It is particularly preferred that an aqueous phase containing a metal group compound is brought into contact with an organic phase that is not arbitrarily mixed with water to form an emulsion.
Examples of means for forming such an emulsion include a stirrer having a predetermined stirring blade, a homogenizer, a homomixer, a colloid mill, a flow jet mixer, a dynamic mixer such as an ultrasonic emulsifier, a static mixer, and the like. It is preferable to use a mixer. The emulsion usually has a droplet diameter of 0.01 μm to 10 μm and has emulsion stability.
The emulsion state of the emulsion is usually represented by the Weber number or P / q (load power value per unit volume). The Weber number is preferably 10,000 or more, more preferably 20,000 or more, and most preferably 35,000 or more. Also, the upper limit is about 1,000,000 or less. P / q is preferably 200 kg · m / L or more, more preferably 500 kg · m / L or more, and most preferably 1,000 kg · m / L or more.

  The contact between the emulsion and the CDC is preferably carried out under a mixing condition that is weaker than the emulsification conditions described above in order to suppress the dissolution of CDC in the organic phase. The Weber number is less than 10,000, preferably less than 5,000, and more preferably less than 2,000. Further, P / q is less than 200 kg · m / L, preferably less than 100 kg · m / L, and more preferably less than 50 kg · m / L. CDC contact can be achieved by introducing CDC into a tubular reactor or tank reactor.

  The reaction temperature in the oligomerization step is usually 80 ° C. or lower, preferably 60 ° C. or lower, more preferably 10 ° C. to 50 ° C. The reaction time is appropriately selected depending on the reaction temperature, and is usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours. If the reaction temperature is excessively high, side reactions cannot be controlled and the CDC basic unit tends to deteriorate. If the reaction temperature is excessively low, this is a favorable situation in terms of reaction control, but the refrigeration load increases and the cost tends to increase.

  The concentration of the carbonate oligomer in the organic phase may be in a range in which the obtained carbonate oligomer is soluble, and is specifically about 10 wt% to 40 wt%. The proportion of the organic phase is preferably a volume ratio of 0.2 to 1.0 with respect to the aqueous phase containing the aqueous alkali metal salt solution or alkaline earth metal salt solution of the dihydroxy compound.

(Polycondensation process)
Next, in the polycondensation step, the organic phase containing the carbonate oligomer separated from the aqueous phase in the stationary separation tank is transferred to an oligomer storage tank having a stirrer. A condensation catalyst such as triethylamine (TEA) is further added to the oligomer storage tank.
Subsequently, the organic phase stirred in the oligomer storage tank is introduced into a predetermined polycondensation reaction tank. Subsequently, an organic solvent such as demineralized water (DMW) or methylene chloride (CH ₂ Cl ₂ ) is added to the polycondensation reaction tank. Then, an aqueous sodium hydroxide solution is supplied and mixed with stirring to carry out a polycondensation reaction of the carbonate oligomer.

Thereafter, the polycondensation reaction liquid in the polycondensation reaction tank is successively introduced successively into a plurality of polycondensation reaction tanks, and the polycondensation reaction of the carbonate oligomer is completed.
Here, in the polycondensation step, the residence time in the polycondensation reaction tank in which the polycondensation reaction of the carbonate oligomer is continuously performed is usually 12 hours or less, preferably 0.5 to 5 hours.
As a preferred embodiment of the polycondensation step, first, an organic phase containing a carbonate oligomer and an aqueous phase are separated, and an inert organic solvent is added to the separated organic phase as necessary to adjust the concentration of the carbonate oligomer. In this case, the amount of the inert organic solvent is adjusted so that the concentration of the polycarbonate resin in the organic phase obtained by the polycondensation reaction is 5% by weight to 30% by weight. Next, an aqueous solution containing water and an alkali metal compound or an alkaline earth metal compound is newly added, and in order to further adjust the polycondensation conditions, a condensation catalyst is preferably added, and a polycondensation reaction is performed according to an interfacial polycondensation method . The ratio of the organic phase to the aqueous phase in the polycondensation reaction is preferably about volume ratio of organic phase: aqueous phase = 1: 0.2 to 1: 1.

Examples of the alkali metal compound or alkaline earth metal compound include compounds similar to those used in the oligomerization step described above. Of these, sodium hydroxide is preferred industrially. The amount of the alkali metal compound or alkaline earth metal compound used may be more than the amount that the reaction system is always kept alkaline during the polycondensation reaction. In addition, it may be divided and added as appropriate during the polycondensation reaction.
When the amount of the alkali metal compound or alkaline earth metal compound used is excessively large, the hydrolysis reaction as a side reaction tends to proceed. Therefore, the concentration of the alkali metal compound or alkaline earth metal compound contained in the aqueous phase after the completion of the polycondensation reaction is 0.05N or more, preferably 0.05N to 0.3N.
The temperature of the polycondensation reaction in the polycondensation step is usually around room temperature. The reaction time is about 0.5 to 5 hours, preferably about 1 to 3 hours.

(Washing process)
Next, after the polycondensation reaction in the polycondensation reaction tank is completed, the polycondensation reaction solution is subjected to alkali washing with an alkali washing solution, acid washing with an acid washing solution, and water washing with washing water by a known method. In addition, the total residence time of the washing process is usually 12 hours or less, preferably 0.5 to 6 hours.

(Polycarbonate resin isolation process)
In the polycarbonate resin isolation step, first, the polycondensation reaction solution containing the polycarbonate resin washed in the washing step is prepared as a concentrated solution concentrated to a predetermined solid content concentration. The solid content concentration of the polycarbonate resin in the concentrate is usually 5% to 35% by weight, preferably 10% to 30% by weight.
Next, the concentrate is continuously supplied to a predetermined granulation tank, and stirred and mixed with demineralized water (DMW) at a predetermined temperature. And the granulation process which evaporates an organic solvent is performed, maintaining a suspended state in water, and the water slurry containing a polycarbonate resin granular material is formed.
Here, the temperature of the demineralized water (DMW) is usually 37 ° C to 67 ° C, preferably 40 ° C to 50 ° C. Moreover, the solidification temperature of polycarbonate resin by the granulation process performed in a granulation tank is 37 to 67 degreeC normally, Preferably, it is 40 to 50 degreeC.
The water slurry containing the polycarbonate resin powder continuously discharged from the granulation tank is then continuously introduced into a predetermined separator, and water is separated from the water slurry.

(Drying process)
In the drying process, in the separator, the polycarbonate resin powder from which water has been separated from the water slurry is continuously supplied to a predetermined dryer, retained for a predetermined residence time, and then continuously extracted. . Examples of the dryer include a fluidized bed dryer. Note that a plurality of fluidized bed dryers may be connected in series to perform the drying process continuously.
Here, the dryer usually has a heating means such as a heat medium jacket, for example, with water vapor, usually 0.1 MPa-G to 1.0 MPa-G, preferably 0.2 MPa-G to 0. .6 MPa-G. Thus, the temperature of nitrogen (N ₂₎ flowing through the dryer, usually, 100 ° C. to 200 DEG ° C., preferably, it is held in 120 ° C. to 180 ° C..

<Melting method>
Next, the melting method will be described.

(Dihydroxy compound)
Specific examples of the dihydroxy compound that is a raw material of the polycarbonate resin according to the present invention include dihydroxy compounds represented by the general formulas (1) to (13).

(Carbonated diester)
Examples of the carbonic acid diester that is a raw material of the polycarbonate resin according to the present invention include compounds represented by the following general formula (14).

Here, in the general formula (14), A ′ is an optionally substituted linear, branched, or cyclic monovalent hydrocarbon group having 1 to 10 carbon atoms. Two A ′ may be the same or different from each other.
In addition, as a substituent on A ′, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, and an ester group Amide group, nitro group and the like.

Specific examples of the carbonic acid diester compound include substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate, and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate.
Among these, diphenyl carbonate (hereinafter sometimes referred to as “DPC”) and substituted diphenyl carbonate are preferable. These carbonic acid diesters can be used alone or in admixture of two or more.

Moreover, the amount of the carbonic acid diester compound is preferably 50 mol% or less, more preferably 30 mol% or less, and may be substituted with dicarboxylic acid or dicarboxylic acid ester.
Typical dicarboxylic acids or dicarboxylic acid esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate, and the like. When substituted with such a dicarboxylic acid or dicarboxylic acid ester, a polyester carbonate is obtained.

  In the production method of the polycarbonate resin by the melting method, the amount of these carbonic acid diesters (including the above-mentioned substituted dicarboxylic acid or dicarboxylic acid ester, the same shall apply hereinafter) is usually the carbonic acid diester compound relative to 1 mol of the dihydroxy compound. Is used in a ratio of 1.01 mol to 1.30 mol, preferably 1.02 mol to 1.20 mol. If the molar ratio of the carbonic acid diester is excessively small, the transesterification rate decreases, making it difficult to produce a polycarbonate resin having a desired molecular weight, or increasing the terminal hydroxyl group concentration of the resulting polycarbonate resin, resulting in thermal stability. Tend to get worse. In addition, if the molar ratio of the carbonic acid diester is excessively large, the reaction rate of the transesterification decreases, and it becomes difficult to produce a polycarbonate resin having a desired molecular weight, and the residual amount of the carbonic acid diester compound in the resin. Is unfavorable because it may cause odor when being molded or formed into a molded product.

(Transesterification catalyst)
Examples of the transesterification catalyst used in the method for producing a polycarbonate resin by a melting method include, but are not particularly limited to, catalysts used for producing a polycarbonate resin by an ester exchange method.
In general, for example, basic compounds such as alkali metal compounds, alkaline earth metal compounds, beryllium compounds, magnesium compounds, basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds can be used. Among these, alkali metal compounds and alkaline earth metal compounds are preferable for practical use. These transesterification catalysts may be used alone or in combination of two or more.

The amount of the transesterification catalyst used is usually in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol with respect to 1 mol of all dihydroxy compounds, in order to obtain a polycarbonate resin excellent in molding characteristics and hue. In the case of using an alkali metal compound and / or an alkaline earth metal compound, the amount of the transesterification catalyst is preferably 1.0 × 10 ⁻⁸ mol to 1 × 10 ^{−4 with} respect to 1 mol of the total dihydroxy compound. Within a range of moles, more preferably within a range of 1.0 × 10 ⁻⁸ moles to 1 × 10 ⁻⁵ moles, particularly preferably 1.0 × 10 ⁻⁷ moles to 5.0 × 10 ⁻⁶ moles. Within range. If the amount is less than the above lower limit amount, the polymerization activity necessary for producing a polycarbonate resin having a desired molecular weight cannot be obtained. If the amount is more than the above upper limit amount, the polymer hue deteriorates, the amount of branching components is too large, and the fluidity. The polycarbonate resin having excellent target melting characteristics cannot be produced.

Examples of the alkali metal compound include inorganic alkali metal compounds such as alkali metal hydroxides, carbonates and hydrogencarbonate compounds; organic alkali metal compounds such as salts with alkali metal alcohols, phenols and organic carboxylic acids. It is done. Here, as an alkali metal, lithium, sodium, potassium, rubidium, cesium etc. are mentioned, for example.
Among these alkali metal compounds, cesium compounds are preferable, and cesium carbonate, cesium hydrogen carbonate, and cesium hydroxide are particularly preferable.

  Examples of the alkaline earth metal compound include inorganic alkaline earth metal compounds such as alkaline earth metal hydroxides and carbonates; alkaline earth metal alcohols, phenols, salts with organic carboxylic acids, and the like. It is done. Here, examples of the alkaline earth metal include calcium, strontium, barium and the like.

  Examples of the beryllium compound and magnesium compound include inorganic metal compounds such as metal hydroxides and carbonates; salts of the metals with alcohols, phenols, and organic carboxylic acids.

  Examples of basic boron compounds include sodium salts, potassium salts, lithium salts, calcium salts, magnesium salts, barium salts, strontium salts, and the like of boron compounds. Here, as the boron compound, for example, tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenylboron, tributyl Examples include benzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, and butyltriphenylboron.

  Examples of the basic phosphorus compound include trivalent phosphine compounds such as triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, and tributylphosphine, or derivatives thereof. And quaternary phosphonium salts.

  Examples of the basic ammonium compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, Triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide Sid, butyl triphenyl ammonium hydroxide, and the like.

  Examples of the amine compound include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2 -Dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.

(Catalyst deactivator)
In the present invention, a catalyst deactivator for neutralizing and deactivating the transesterification catalyst may be added after completion of the transesterification reaction. The heat resistance and hydrolysis resistance of the polycarbonate resin obtained by such treatment are improved.
As such a catalyst deactivator, an acidic compound having a pKa of 3 or less, such as sulfonic acid and sulfonic acid ester, is preferable. Specifically, benzenesulfonic acid, p-toluenesulfonic acid, methyl benzenesulfonate, benzenesulfone Examples include ethyl acetate, propyl benzenesulfonate, butyl benzenesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, propyl p-toluenesulfonate, and butyl p-toluenesulfonate.
Among these, p-toluenesulfonic acid and butyl p-toluenesulfonate are preferably used.

The method for producing a polycarbonate resin by a melting method is to prepare a raw material mixed melt of a raw material dihydroxy compound and a carbonic acid diester (original preparation step), and the raw material mixed melt is melted in the presence of a transesterification reaction catalyst. The polycondensation reaction is performed in multiple stages using a plurality of reaction tanks (polycondensation step). The reaction system may be any of a batch system, a continuous system, or a combination of a batch system and a continuous system. As the reaction tank, a plurality of vertical stirring reaction tanks and, if necessary, at least one horizontal stirring reaction tank subsequent thereto are used. Usually, these reaction tanks are installed in series and processed continuously.
After the polycondensation process, the reaction is stopped, the unreacted raw materials and reaction byproducts in the polycondensation reaction liquid are devolatilized and removed, the process of adding a thermal stabilizer, mold release agent, colorant, etc., polycarbonate resin You may add suitably the process etc. which form in a predetermined particle size.
Next, each process of the manufacturing method will be described.

(Primary process)
The dihydroxy compound and the carbonic acid diester compound used as the raw material of the polycarbonate resin are usually raw materials using a batch type, semi-batch type or continuous type stirring tank type apparatus in an atmosphere of an inert gas such as nitrogen or argon. Prepared as a mixed melt. For example, when bisphenol A is used as the dihydroxy compound and diphenyl carbonate is used as the carbonic acid diester compound, the melt mixing temperature is usually selected from the range of 120 ° C. to 180 ° C., preferably 125 ° C. to 160 ° C.
Hereinafter, the case where bisphenol A is used as a dihydroxy compound and diphenyl carbonate is used as a carbonic acid diester compound as raw materials will be described as an example.
At this time, the ratio of the dihydroxy compound and the carbonic acid diester compound is adjusted so that the carbonic acid diester compound becomes excessive. The carbonic acid diester compound is usually 1.01 mol to 1.30 mol with respect to 1 mol of the dihydroxy compound. Preferably, it is adjusted to a ratio of 1.02 mol to 1.20 mol.

(Polycondensation process)
The polycondensation by the transesterification reaction between the dihydroxy compound and the carbonic acid diester compound is usually carried out continuously in a multistage system of two or more stages, preferably 3 to 7 stages. Specific reaction conditions for each stage are temperature: 150 ° C. to 320 ° C., pressure: normal pressure to 0.01 Torr (1.3 Pa), and average residence time: 5 minutes to 150 minutes.
In each multi-stage reactor, in order to more effectively remove monohydroxy compounds such as phenol as a by-product from the system as the transesterification progresses, the reaction temperature is increased stepwise in the above reaction conditions. Set to high vacuum.

When the polycondensation step is performed in a multistage manner, usually, a plurality of reaction vessels including a vertical stirring reaction vessel are provided to increase the average molecular weight of the polycarbonate resin. The reaction tank is usually installed in 2 to 6 groups, preferably 4 to 5 groups.
Here, as a reaction tank, for example, a stirring tank type reaction tank, a thin film reaction tank, a centrifugal thin film evaporation reaction tank, a surface renewal type biaxial kneading reaction tank, a biaxial horizontal type stirring reaction tank, a wet wall reaction tank, a free tank A perforated plate type reaction vessel that polycondenses while dropping, a perforated plate type reaction vessel with wire that polycondenses while dropping along a wire, and the like are used.

  The types of stirring blades in the vertical stirring reaction tank include, for example, turbine blades, paddle blades, fiddler blades, anchor blades, full zone blades (manufactured by Shinko Environmental Solution Co., Ltd.), Sun Meller blades (manufactured by Mitsubishi Heavy Industries, Ltd.), Max blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), helical ribbon blades, twisted lattice blades (manufactured by Hitachi Plant Technology Co., Ltd.), and the like.

  Moreover, a horizontal stirring reaction tank means that the rotating shaft of a stirring blade is a horizontal type (horizontal direction). As a stirring blade of a horizontal stirring reaction tank, for example, a uniaxial stirring blade such as a disk type or a paddle type, HVR, SCR, N-SCR (manufactured by Mitsubishi Heavy Industries, Ltd.), Vivolak (Sumitomo Heavy Industries, Ltd.) )), Or biaxial stirring blades such as spectacle blades and lattice blades (manufactured by Hitachi Plant Technology Co., Ltd.).

  In addition, the transesterification catalyst used for the polycondensation of a dihydroxy compound and a carbonic acid diester compound may usually be prepared as a solution in advance. The concentration of the catalyst solution is not particularly limited, and is adjusted to an arbitrary concentration according to the solubility of the catalyst in the solvent. As the solvent, acetone, alcohol, toluene, phenol, water and the like can be appropriately selected.

  When water is selected as the solvent for the catalyst, the nature of the water is not particularly limited as long as the type and concentration of impurities contained are constant, but usually distilled water or deionized water is preferably used.

<Configuration of polycarbonate resin sheet>
The configuration of the polycarbonate resin sheet of the present invention is not particularly limited, such as one type of polycarbonate resin, a polycarbonate resin composition composed of two or more types of polycarbonate resins, and the polycarbonate resin (a) is different from the polycarbonate resin (a). It is preferable to include at least a polycarbonate resin (b) having a structural unit. That is, it is preferable to use a polycarbonate resin composition containing the polycarbonate resin (a) and the polycarbonate resin (b) as a sheet. The method of making a polycarbonate resin composition is:
1) A method of melt-kneading the polycarbonate resin (a) and the polycarbonate resin (b);
2) A method of melt-kneading the molten polycarbonate resin (a) and the molten polycarbonate resin (b);
3) A method of mixing the polycarbonate resin (a) and the polycarbonate resin (b) in a solution state;
4) A method of dry blending the polycarbonate resin (a) and the polycarbonate resin (b);
Etc.
Hereinafter, each method will be described.

1) A method of melt-kneading the polycarbonate resin (a) and the polycarbonate resin (b);
The pellets or granules of the polycarbonate resin (a) and the pellets or granules of the polycarbonate resin (b) are melt kneaded using a mixing device such as a kneader, a twin screw extruder, or a single screw extruder. The pellets or granules of the polycarbonate resin (a) and the pellets or granules of the polycarbonate resin (b) may be mixed in advance in a solid state and then kneaded, or either one may be mixed with the mixing device first. It may be melted and the other polycarbonate resin added thereto and kneaded. The kneading temperature is not particularly limited, but is preferably 240 ° C or higher, more preferably 260 ° C or higher, and further preferably 280 ° C or higher. Moreover, 350 degrees C or less is preferable and 320 degrees C or less is especially preferable. If the kneading temperature is low, mixing of the polycarbonate resin (a) and the polycarbonate resin (b) is not complete, and there is a possibility that the pencil hardness and the like may vary when the polycarbonate resin sheet is produced, which is not preferable. Moreover, when the kneading | mixing temperature is too high, the color tone of a polycarbonate resin sheet may deteriorate, and it is unpreferable.

2) A method of melt-kneading the molten polycarbonate resin (a) and the molten polycarbonate resin (b);
The molten polycarbonate resin (a) and the molten polycarbonate resin (b) are mixed using a mixing device such as a stirring tank, a static mixer, a kneader, a twin screw extruder, or a single screw extruder. At this time, for example, a polycarbonate resin obtained by a melt polymerization method may be introduced into the mixing apparatus in a molten state without being cooled and solidified. Although there is no restriction | limiting in particular as temperature to mix, 150 degreeC or more is preferable, 180 degreeC or more is more preferable, and 200 degreeC or more is further more preferable. Moreover, 300 degrees C or less is preferable and 250 degrees C or less is especially preferable. If the mixing temperature is low, the mixing of the polycarbonate resin (a) and the polycarbonate resin (b) is not complete, and when the polycarbonate resin sheet is produced, the pencil hardness and the like may vary, which is not preferable. Moreover, when the temperature to mix is too high, the color tone of a polycarbonate resin sheet may deteriorate, and it is not preferable.

3) A method of mixing the polycarbonate resin (a) and the polycarbonate resin (b) in a solution state;
In this method, the polycarbonate resin (a) and the polycarbonate resin (b) are dissolved in an appropriate solvent to form a solution, mixed in a solution state, and then isolated as a polycarbonate resin composition. Suitable solvents include, for example, aliphatic hydrocarbons such as hexane and n-heptane; chlorinated aliphatic carbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane and 1,2-dichloroethylene. Hydrogen; aromatic hydrocarbons such as benzene, toluene and xylene; and other substituted aromatic hydrocarbons such as nitrobenzene and acetophenone. Among these, for example, chlorinated hydrocarbons such as dichloromethane or chlorobenzene are preferably used. These solvents can be used alone or as a mixture with other solvents.
Examples of the mixing device include a stirring tank and a static mixer. Further, the mixing temperature is not particularly limited as long as the polycarbonate resin (a) and the polycarbonate resin (b) are dissolved, and the mixing temperature is usually carried out below the boiling point of the solvent used.

4) A method of dry blending the polycarbonate resin (a) and the polycarbonate resin (b);
In this method, pellets or granules of polycarbonate resin (a) and pellets or granules of polycarbonate resin (b) are dry blended using a tumbler, super mixer, Henschel mixer, Nauter mixer or the like.

Among the methods 1) to 4) above, the methods 1) and 2) in which the polycarbonate resin (a) and the polycarbonate resin (b) are melt-kneaded, and the polycarbonate resin (a) and the polycarbonate resin (b) are dry blended. The method 4) is preferred.
In producing the composition, in any of the above methods, a pigment, a dye, a release agent, a heat stabilizer and the like can be appropriately added within a range not impairing the object of the present invention.
In the polycarbonate resin sheet of the present invention, the weight ratio of the polycarbonate resin (a) to the polycarbonate resin (b) is usually in the range of 1:99 to 45:55, preferably 3:97 to 45:55, More preferably, it is 5: 95-40: 60, More preferably, it is 10: 90-30: 70. When the proportion of the polycarbonate resin (a) is too large, the color tone of the obtained polycarbonate resin sheet tends to deteriorate, and when the proportion of the polycarbonate resin (a) is too small, the pencil hardness may be insufficient.

"Production method of polycarbonate resin sheet"
Although the manufacturing method of the polycarbonate resin sheet of the said invention is not specifically limited, Usually, the extrusion molding method, the compression molding method, and the casting method are mentioned. Of these, an extrusion molding method using an extrusion molding machine or the like, and a compression molding method using a compression molding machine or the like, in which the surface hardness or the like tends to be uniform over the entire surface of the sheet, are preferable.
Hereinafter, the extrusion molding method will be described in detail as an example.

  The barrel temperature of the extruder when producing a polycarbonate resin sheet using an extruder is not particularly limited, but is preferably 360 ° C. or lower, more preferably 340 ° C. or lower, and most preferably 320 ° C. or lower. Moreover, 220 degreeC or more is preferable, 240 degreeC or more is more preferable, and 260 degreeC or more is especially preferable. If the barrel temperature is too high, the melt viscosity becomes low and sheet molding becomes difficult. If the barrel temperature is too low, the melt viscosity increases and the resin pressure increases, so that the T-die may be blocked. Note that a die called a T die having a specific thickness is usually attached to the extruder, and a polycarbonate resin sheet is extruded from the T die in a molten state. Next, the extruded polycarbonate resin sheet in a molten state is cooled by a roll, and becomes a polycarbonate resin sheet having a uniform thickness. The roll temperature is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and most preferably 160 ° C. or lower. Moreover, 60 degreeC or more is preferable and 80 degreeC or more is especially preferable. If the roll temperature is too high, the molten polycarbonate resin sheet extruded from the T-die remains attached to the cooling roll, and the sheet cannot be molded. If the roll temperature is too low, the molten polycarbonate resin sheet extruded from the T-die is rapidly cooled on the cooling roll to generate gear marks, resulting in poor surface smoothness of the sheet.

  The thickness of the polycarbonate resin sheet in the present invention is preferably 1 μm to 2000 μm, the upper limit is more preferably 1800 μm, still more preferably 1500 μm, and the lower limit is more preferably 10 μm, still more preferably 50 μm. If the polycarbonate resin sheet is too thick, even if the sheet surface is cooled on the cooling roll, the inside of the sheet is cooled later, and the inside contracts to deteriorate the surface smoothness of the sheet. If the polycarbonate resin sheet is too thin, it is easily torn and is not suitable for practical use.

  The polycarbonate resin sheet can be used in various fields such as buildings, vehicles, electrical / electronic devices, machinery and the like.

Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to a following example. The physical properties of the polycarbonate resin sheet used in the examples were evaluated by the following methods.

(1) Pencil hardness of polycarbonate resin sheet About the polycarbonate resin sheet, the pencil hardness measured by 750g load was calculated | required using the pencil hardness tester (made by Toyo Seiki Co., Ltd.) based on ISO15184.

(2) Yellow index (YI) of methylene chloride solution of polycarbonate resin sheet
The polycarbonate resin sheet was dissolved in methylene chloride to give a 7% by weight methylene chloride solution. Next, the methylene chloride solution was placed in a quartz cell having a container inner width of 50 mm, and the yellow index (solution YI) was measured with a color difference meter (SM color computer SM-4-2, manufactured by Suga Test Instruments Co., Ltd.). The smaller the value, the better the color tone.

(3) Viscosity average molecular weight of polycarbonate resin (Mv)
The polycarbonate resin was dissolved in methylene chloride (concentration 6.0 g / L), the specific viscosity (ηsp) at 20 ° C. was measured using an Ubbelohde viscosity tube, and the viscosity average molecular weight (Mv) was calculated by the following formula.
ηsp / C = [η] (1 + 0.28ηsp)
[η] = 1.23 × 10 ⁻⁴ Mv ^0.83

In addition, the polycarbonate resin used by the Example and the comparative example is as follows.
Reference Example 1 Synthesis of BPC homopolymer 1 (melting method)
37.60 kg (about 147 mol) of 2,2-bis (4-hydroxy-3-methylphenyl) propane (hereinafter sometimes abbreviated as “BPC”) (Honshu Chemical Co., Ltd.) and diphenyl carbonate (DPC) 32 The mixture was prepared by adding an aqueous solution of cesium carbonate to .20 kg (about 150 mol) so that cesium carbonate was 2 μmol per mol of dihydroxy compound. Next, the mixture was charged into a first reactor having an internal volume of 200 L equipped with a stirrer, a heating medium jacket, a vacuum pump, and a reflux condenser.
Next, the operation of depressurizing the inside of the first reactor to 1.33 kPa (10 Torr) and then restoring the pressure to the atmospheric pressure with nitrogen was repeated 5 times, and the inside of the first reactor was replaced with nitrogen. After nitrogen substitution, the internal temperature of the first reactor was gradually raised through a heat medium having a temperature of 230 ° C. through the heat medium jacket to dissolve the mixture. Then, the stirrer was rotated at 300 rpm, the temperature in the heating medium jacket was controlled, and the internal temperature of the first reactor was kept at 220 ° C. The pressure in the first reactor was 101.3 kPa (760 Torr) in absolute pressure over 40 minutes while distilling off phenol produced as a by-product by the oligomerization reaction of BPC and DPC performed in the first reactor. To 13.3 kPa (100 Torr).
Subsequently, a transesterification reaction was performed for 80 minutes while maintaining the pressure in the first reactor at 13.3 kPa and further distilling off the phenol.
Thereafter, the inside of the system was restored to the absolute pressure of 101.3 kPa with nitrogen, the gauge pressure was increased to 0.2 MPa, and the oligomer in the first reactor was passed through a transfer pipe heated to 200 ° C. or higher in advance. Was pumped to the second reactor. The second reactor had an internal volume of 200 L, was equipped with a stirrer, a heat medium jacket, a vacuum pump, and a reflux condenser, and the internal pressure was controlled to atmospheric pressure and the internal temperature was controlled to 240 ° C.
Next, the oligomer fed into the second reactor was stirred at 38 rpm, the internal temperature was raised with a heating medium jacket, and the inside of the second reactor was absolute pressure from 101.3 kPa to 13.3 kPa over 40 minutes. The pressure was reduced to. Thereafter, the temperature increase was continued, and the internal pressure was reduced from 13.3 kPa to 399 Pa (3 Torr) as an absolute pressure over an additional 40 minutes, and phenol distilled out was removed out of the system. Further, the temperature was continuously raised, and after the absolute pressure in the second reactor reached 70 Pa (about 0.5 Torr), the pressure was maintained at 70 Pa, and a polycondensation reaction was performed. The final internal temperature in the second reactor was 285 ° C. The polycondensation reaction was completed when the stirrer of the second reactor reached a predetermined stirring power.
Next, the inside of the second reactor is restored to 101.3 kPa in absolute pressure with nitrogen, and the gauge pressure is increased to 0.2 MPa, and the polycarbonate resin is extracted in a strand form from the bottom of the second reactor, The mixture was pelletized by using a rotary cutter while being cooled at the same time. The resulting polycarbonate resin had a viscosity average molecular weight of 31,800.

Reference Example 2 Synthesis of BPC homopolymer 2 (melting method)
A polycarbonate resin was produced in the same manner as in Reference Example 1 except that the value of the predetermined stirring power of the second reactor was changed. The resulting polycarbonate resin had a viscosity average molecular weight of 34,500.

Reference Example 3 Synthesis of BPC homopolymer 3 (melting method)
A transesterification reaction was carried out in the first reactor in the same manner as in Reference Example 1.
Thereafter, the inside of the system was restored to the absolute pressure of 101.3 kPa with nitrogen, the gauge pressure was increased to 0.2 MPa, and the oligomer in the first reactor was passed through a transfer pipe heated to 200 ° C. or higher in advance. Was pumped to the second reactor. The second reactor had an internal volume of 200 L, was equipped with a stirrer, a heat medium jacket, a vacuum pump, and a reflux condenser, and the internal pressure was controlled to atmospheric pressure and the internal temperature was controlled to 240 ° C.
Next, the oligomer pumped into the second reactor was stirred at 38 rpm, the internal temperature was raised with a heating medium jacket, and the absolute pressure in the second reactor was increased from 101.3 kPa to 13.3 kPa over 40 minutes. The pressure was reduced. Thereafter, the temperature was continuously increased, and the internal pressure was reduced from 13.3 kPa to 900 Pa (6.8 Torr) in absolute pressure over 38 minutes to remove the distilled phenol out of the system, and a polycondensation reaction was performed. . The internal temperature in the second reactor was 282 ° C. At this point, the polycondensation reaction was completed.
Subsequently, the inside of the second reactor was restored to an absolute pressure of 101.3 kPa with nitrogen and then increased to 0.2 MPa with a gauge pressure, and the polycarbonate resin was extracted from the bottom of the tank of the second reactor as a lump. After the extraction, the bulky polycarbonate resin was crushed to obtain a granular polycarbonate resin. The resulting polycarbonate resin had a viscosity average molecular weight of 6,700.

Reference Example 4 Synthesis of BPC / BPA (30/70 wt%) copolymer (melting method)
A polycarbonate resin was obtained in the same manner as in Reference Example 1 except that BPC (Honshu Chemical Co., Ltd.) 10.11 kg and BPA (Mitsubishi Chemical Co., Ltd.) 23.60 kg were used as raw materials. The viscosity average molecular weight of the obtained polycarbonate resin was 25,200.

(Reference Example 5) BPA homopolymer 1 (melting method)
As the BPA homopolymer 1, a commercially available polycarbonate resin (M7022J manufactured by Mitsubishi Engineering Plastics Co., Ltd.) formed by a melting method composed only of monomer units derived from BPA was used. The viscosity average molecular weight of the BPA homopolymer 1 was 20,600.

(Reference Example 6) BPA homopolymer 2 (melting method)
As the BPA homopolymer 2, a commercially available polycarbonate resin (M7027J, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) using only a monomer unit derived from BPA was used. The viscosity average molecular weight of the BPA homopolymer 2 was 25,600.

"Example 1"
As a polycarbonate resin (a) and a polycarbonate resin (b), a BPC homopolymer 1 and a BPA homopolymer 2 were respectively fed to a Nippon Steel Works twin screw extruder (LABOTEX30HSS-32) having one vent port in the ratio shown in Table 1. The mixture was melt-kneaded, extruded into a strand form from the exit of the twin-screw extruder, cooled and solidified with water, and then pelletized with a rotary cutter to obtain polycarbonate resin pellets. At this time, the barrel temperature of the twin screw extruder was 280 ° C., and the temperature of the polycarbonate resin at the outlet of the twin screw extruder was 300 ° C. During melt kneading, the vent port of the twin screw extruder was connected to a vacuum pump, and the pressure at the vent port was controlled to 500 Pa.
Next, using the obtained polycarbonate resin pellets, a polycarbonate having a thickness of 500 μm and a width of 300 ± 10 mm under the barrel temperature and roll temperature conditions shown in Table 1 using a T-die extrusion molding machine (manufactured by Soken). Resin sheet extrusion was performed.
The obtained polycarbonate resin sheet was evaluated for pencil hardness and solution YI according to the method described in the above evaluation items. The results are shown in Table 1.

"Examples 2-3, 5 and Comparative Examples 3-5"
Examples 2 to 3 are the same as Example 1 except that two types of polycarbonate resins shown in Table 1 are used as the polycarbonate resin (a) and the polycarbonate resin (b), and the sheet molding conditions shown in Table 1 are used. 5 and Comparative Examples 3 to 5 were obtained. Furthermore, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

"Comparative Examples 1, 2, 6"
As shown in Table 1, BPC homopolymer is used as Comparative Example 1, BPA homopolymer 2 is used as Comparative Example 2, and BPC / BPA (30/70 wt%) copolymer is used as Comparative Example 6, each shown in Table 1. The polycarbonate resin sheets of Comparative Examples 1, 2, and 6 were obtained in the same manner as in Example 1 except that the sheet molding conditions were used. Further, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
As a polycarbonate resin (a) and a polycarbonate resin (b), a BPC homopolymer 2 and a BPA homopolymer 1 are respectively supplied to a Nippon Steel Works twin screw extruder (LABOTEX30HSS-32) having one vent port in the ratio shown in Table 1. The mixture was melt-kneaded, extruded into a strand form from the exit of the twin-screw extruder, cooled and solidified with water, and then pelletized with a rotary cutter to obtain polycarbonate resin pellets. At this time, the barrel temperature of the twin screw extruder was 280 ° C., and the temperature of the polycarbonate resin at the outlet of the twin screw extruder was 300 ° C. During melt kneading, the vent port of the twin screw extruder was connected to a vacuum pump, and the pressure at the vent port was controlled to 500 Pa.
Next, using the obtained polycarbonate resin pellets, a thickness of 240 μm, a width of 150 ± on a barrel temperature and roll temperature conditions described in Table 1 using a 25 mmφ single screw extruder (manufactured by Isuzu Chemical Industries Ltd.). A 10 mm polycarbonate resin sheet was extruded.
The obtained polycarbonate resin sheet was evaluated for pencil hardness and solution YI according to the method described in the above evaluation items. The results are shown in Table 1.

“Comparative Example 7”
A polycarbonate resin sheet of Comparative Example 7 was obtained in the same manner as in Example 4 except that the two types of polycarbonate resins shown in Table 1 were used and the sheet molding conditions shown in Table 1 were used. Furthermore, various evaluations were performed in the same manner as in Example 4. The results are shown in Table 1.

When Examples 1 to 4 and Comparative Example 6 are compared, the content of the structural unit (a) (the structural unit derived from BPC) of the entire polycarbonate resin sheet is the same, but Examples 1 to 4 have a pencil hardness. And the solution yellow index (solution YI) are both good. However, it can be seen that Comparative Example 6 has a high solution yellow index (solution YI).
Further, when Examples 1 to 4 and Comparative Examples 3 to 5 are compared, Comparative Examples 3 to 5 have Examples 1 to 4 in which the content of the structural unit (a) (the structural unit derived from BPC) of the entire polycarbonate resin sheet is. However, the pencil hardness is only increased by about one rank, and it can be seen that the solution yellow index (solution YI) is much worse.

  According to the present invention, a polycarbonate resin sheet having a significantly improved surface hardness and color tone can be obtained. The polycarbonate resin sheet is used in the field of electrical and electronic equipment such as mobile phones, personal computers and displays, OA related products, the field of automobiles such as headlamp lenses and vehicle windows, the field of building materials such as lighting and exteriors, signboards and display boards, etc. In particular, it is possible to expand the application field to applications requiring surface hardness.

Claims (8)

  A polycarbonate resin sheet having a pencil hardness defined by ISO15184 of F or higher and a yellow index of a polycarbonate resin sheet measured with a 7% by weight methylene chloride solution at an optical path length of 50 mm is 6.8 or lower. A polycarbonate resin sheet.   The polycarbonate resin sheet according to claim 1, wherein the polycarbonate resin sheet includes at least a polycarbonate resin (a) and a polycarbonate resin (b) having a structural unit different from the polycarbonate resin (a). The polycarbonate resin sheet according to claim 2, wherein the polycarbonate resin (a) is a polycarbonate resin containing at least a structural unit derived from a compound represented by the following general formula (1).

(In General Formula (1), R ¹ and R ² each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, and R ³ and R 2 ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group, and X represents a single bond, a carbonyl group, a substituted or unsubstituted group. An alkylidene group, a substituted or unsubstituted sulfur atom, or an oxygen atom.) The polycarbonate resin (a) is a polycarbonate resin containing at least a structural unit derived from at least one compound selected from the group consisting of the following general formulas (1a) to (1c). The polycarbonate resin sheet described in 1.

The polycarbonate resin according to any one of claims 2 to 4, wherein a weight ratio of the polycarbonate resin (a) to the polycarbonate resin (b) is in a range of 1:99 to 45:55. Sheet.   The polycarbonate resin sheet according to any one of claims 2 to 5, wherein Mv (a), which is a viscosity average molecular weight of the polycarbonate resin (a), is 10,000 or more and 50,000 or less. The polycarbonate according to any one of claims 2 to 6, wherein the polycarbonate resin (b) is a polycarbonate resin mainly containing a structural unit derived from a compound represented by the following general formula (2). Resin sheet.

  The polycarbonate resin sheet according to any one of claims 1 to 7, wherein the thickness of the polycarbonate resin sheet is 1 µm to 2000 µm.