JPH1017759A - Weather resistant polycarbonate sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a weather resistant polycarbonate sheet capable of maintaining the weather resistant properties even after secondary processing such as a thermoforming and preventing an ultraviolet absorber from being lost during forming the sheet and to provide a method for producing the sheet. SOLUTION: This weather resistant polycarbonate sheet is composed of a polycarbonate having a little amount of different bond and blended with 0.01-20wt.% ultraviolet absorber. The method for producing the weather resistant polycarbonate sheet comprises an extrusion of the raw composition for the sheet comprising the polycarbonate having a little amount of the different bond from a sheet-forming machine while adjusting the temperature of the composition to 240-290 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a weather-resistant polycarbonate sheet and a method for producing the same.

[0002]

2. Description of the Related Art Polycarbonate sheets are excellent in impact resistance, transparency, flame resistance, etc., and are used for building materials such as window materials, carport roofing materials, lapel boards on verandas, road materials such as transparent soundproofing boards, and railways. It is used in various fields such as vehicle materials, and its use is expected to expand in the future.

However, polycarbonate sheets have the disadvantage of poor weather resistance, and particularly when used in places exposed to ultraviolet light, such as outdoors, a decrease in optical performance such as yellowing or loss, a decrease in tensile strength, and a decrease in impact resistance. The mechanical properties such as the above were deteriorated, which was a problem. A commonly used measure to improve the weather resistance of polycarbonate sheets is to incorporate an ultraviolet absorber. In particular, in recent years, a number of methods have been proposed for coating the surface of a polycarbonate sheet with a thin skin of polycarbonate containing a large amount of an ultraviolet absorber. And the like.

When a polycarbonate is formed into a sheet, a powdery or pelletized polycarbonate raw material is heated, melted and kneaded in a molding machine by an extrusion molding method, extruded into a sheet through a T-die or the like, and then extruded into a sheet.
A method of cooling and solidifying into a sheet using four polishing rolls (glazing rolls) is often used. Polycarbonate has a problem that it is colored when molded at high temperature. However, in the current polycarbonate sheet molding technology, when the molding temperature is lowered, the load on the molding machine increases and stable production cannot be performed. Molded with. In order to lower the molding temperature, studies have been made to lower the molecular weight of polycarbonate and make it easier to flow. However, resin dripping occurs between the T-die and the polishing roll and molding cannot be performed. It is difficult, and how to mold at a low molding temperature, that is, a resin temperature close to about 240 ° C., which is the melting point of polycarbonate, is an issue in polycarbonate molding technology.

At present, when a polycarbonate containing an ultraviolet absorber is formed into a sheet at a high molding temperature, the compounded ultraviolet absorber is volatilized during molding, and the ultraviolet absorber in the sheet product is initially removed. , The effect of improving the weather resistance is not as expected as a problem. In addition, this volatile ultraviolet absorber adheres to the surface of a T-die or a polishing roll, and contaminates the surface of a sheet product, and requires wiping and cleaning. Had occurred.

If the amount of the ultraviolet absorber is increased in anticipation of volatile components, the surface of the T-die and the polishing roll frequently become dirty, making it difficult to obtain a sheet having a good appearance. Until now, there was no good molding method because the load on the machine increased and molding could not be performed. In addition, polycarbonate sheets are generally used after being formed into a predetermined shape by secondary processing such as thermoforming, and as described above, even if a sheet in which the amount of an ultraviolet absorber is increased in anticipation of volatile components is obtained. However, since the loss of the ultraviolet absorber occurs again in such thermoforming, the weatherability cannot be maintained as a molded product of the sheet, and thus improvement is required.

[0007] For this reason, studies on UV absorbers which are difficult to volatilize have been actively conducted, and UV absorbers having small weight loss even at high temperatures have been proposed. For example, JP-A-62-1
No. 46952, JP-A-5-93089, and the like. Certainly, these UV absorbers have reduced weight loss at high temperatures, but improvement of the UV absorber alone is still insufficient, and there is a need for a polycarbonate that can be formed into a sheet at a low molding temperature.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polycarbonate sheet which maintains weather resistance even after secondary processing such as thermoforming, and to prevent loss of an ultraviolet absorber generated during sheet molding. An object of the present invention is to provide a method for producing the weather-resistant polycarbonate sheet.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors diligently studied a polycarbonate resin. As a result, the polycarbonate obtained by the transesterification method has several kinds of heterogeneous bonds. As well as finding
It has been found that by setting the amount of the hetero bond to a specific range, non-Newtonian flow behavior can be maintained. When a raw material composition in which an ultraviolet absorber was blended with this polycarbonate was formed into a sheet, surprisingly, this polycarbonate sheet raw material composition can be formed at a lower temperature compared to a composition using a conventional polycarbonate having the same molecular weight. And, the obtained polycarbonate sheet can be thermoformed at a low temperature, there is almost no loss of the ultraviolet absorber during the thermoforming, and it has been found that the weather resistance can be maintained even after the thermoforming of the sheet. Things.

That is, the present invention relates to (1) a polycarbonate comprising a small amount of a heterogeneous bond, wherein the ultraviolet absorber is 0.01 wt.
(2) a polycarbonate having a small amount of heterogeneous bond is a polycarbonate produced by transesterification from an aromatic dihydroxy compound and a carbonic acid diester, and the polycarbonate is completely After hydrolysis, methanol and 0.1%
A mixed eluent consisting of an aqueous phosphoric acid solution, methanol / 0.1.
Starting from 20/80 1% phosphoric acid aqueous solution ratio
When measured under conditions of a gradient to 0/0,
The total amount of compounds having a retention time longer than that of the aromatic dihydroxy compound (the amount calculated from the peak area using the extinction coefficient of salicylic acid detected by a UV detector having a wavelength of 300 nm, excluding the carbonic diester) is the polycarbonate. (1) The polycarbonate sheet is in the range of 0.01 to 0.10% by weight, and (3) 85 mol% or more of the aromatic dihydroxy compound is bisphenol A. (4) The total amount A of the compound having a retention time between bisphenol A and diphenyl carbonate.
(However, the ratio B / A between the other aromatic dihydroxy compound used and diphenyl carbonate) and the total amount B of the compound after diphenyl carbonate (however, excluding the other aromatic dihydroxy compound used and diphenyl carbonate) But,
(1) to (3), which are 0.8 or less.
(5) The weatherable polycarbonate sheet according to (1) to (4), wherein the ultraviolet absorber comprises a benzotriazole-based compound; and (6) the ultraviolet absorber. (1) to (1) comprising a hydroxyphenyltriazine compound
(4) A weather-resistant polycarbonate sheet as described in (4). Further, in the molding of the weather-resistant polycarbonate sheet according to the above (1) to (6), the resin temperature of the polycarbonate sheet raw material composition discharged from the sheet molding machine is adjusted to 240 to 290 ° C. It relates to a sheet manufacturing method.

Hereinafter, the present invention will be described in detail. The weatherable polycarbonate sheet of the present invention is a sheet made of a composition obtained by blending a UV absorber with a small amount of a polycarbonate having a heterogeneous bond. It is a sheet that can be formed, hardly loses the ultraviolet absorber even after thermoforming, and maintains weather resistance even after thermoforming.

The polycarbonate having a small amount of heterogeneous bond, which is a raw material of the polycarbonate sheet of the present invention, is produced by a transesterification method. The polycarbonate is completely hydrolyzed and is subjected to reverse phase liquid chromatography. When a ratio of methanol / 0.1% phosphoric acid aqueous solution was measured from 20/80 to 100/0 with a mixed eluent composed of methanol and 0.1% phosphoric acid aqueous solution, retention was measured. The total amount of compounds whose thyme is longer than the aromatic dihydroxy compound (the amount calculated from the peak area using the extinction coefficient of salicylic acid, detected with a UV detector at a wavelength of 300 nm, excluding the carbonate diester) is included in the polycarbonate. On the other hand, it must be in the range of 0.01 to 0.10% by weight. The compound is presumed to be due to a heterogeneous bond produced as a by-product in the process of producing a polycarbonate by the transesterification method. If the total amount of the compound is less than the above range, the non-Newtonian flow behavior decreases, so The fluidity under the shear, that is, the molding fluidity, is unfavorably decreased, and if it is more than the above range, the mechanical properties such as tensile elongation and IZOD impact strength are undesirably decreased. Preferably, 0.
It is in the range of 015 to 0.09% by weight, more preferably in the range of 0.02 to 0.08% by weight.

The hydrolysis of polycarbonate can be easily performed, and the method of complete hydrolysis is not particularly limited.
ymer Degradation and Stab
The method of hydrolysis at room temperature as described in ility 45 (1994), 127 to 137 is preferable since the polycarbonate can be completely hydrolyzed without a side reaction in the decomposition process. In the present invention, the polycarbonate 55m
g was dissolved in 2 ml of tetrahydrofuran, and 0.5 ml of 5N methanolic potassium hydroxide solution was added, followed by stirring at room temperature for 2 hours to completely hydrolyze. Thereafter, 0.3 ml of concentrated hydrochloric acid was added, and measurement was performed by reversed-phase liquid chromatography.

In reversed-phase liquid chromatography, a mixed eluent consisting of methanol and a 0.1% phosphoric acid aqueous solution is used as the eluent, and the methanol / 0.1% phosphoric acid aqueous solution ratio is started from 20/80 and 100/0. The measurement was performed under the condition of a gradient up to, and the detection was calculated from the peak area using a 300 nm wavelength UV detector, and the quantification was performed using the extinction coefficient of salicylic acid. In the present invention, other conditions are not particularly limited, but analysis was performed under the following conditions.

Column: Inertsil O, GL Science Company
DS-3 (registered trademark) Flow rate: 1 ml / min Injection volume: 20 μl An example of an analysis chart analyzed by this method is shown in FIGS. 1 and 2. FIG. 1 is a liquid chromatography chart of a pure compound, wherein peak 3 is bisphenol A, a typical aromatic dihydroxy compound, and peak 4 is diphenyl carbonate, a typical carbonic diester.
FIG. 2 is a reversed-phase liquid chromatography chart of a completely hydrolyzed polycarbonate polymerized by transesterification using bisphenol A as an aromatic dihydroxy compound and diphenyl carbonate as a carbonic acid diester. In FIG. 2, peak number 8 is bisphenol A, and subsequent peaks 9 to 17 are compounds considered to be based on heterogeneous bonds.

In the present invention, when polycarbonate is used in which 85% by mole or more of bisphenol A is used as the aromatic dihydroxy compound, the polycarbonate is completely hydrolyzed, and the retention is measured when measured by reverse phase liquid chromatography. Thyme is bisphenol A
And the total amount of compounds A (excluding the other aromatic dihydroxy compound and diphenyl carbonate used) and the total amount of compounds after the diphenyl carbonate B (however, other aromatic dihydroxy compounds and carbonates used). Excluding diphenyl) (B / A)
It is preferably at most 0.8. If B / A exceeds 0.8, the mechanical properties tend to decrease, which is not preferable.

The polycarbonate used in the present invention is:
It is produced by transesterification from an aromatic dihydroxy compound and a carbonic acid diester. In the present invention, the aromatic dihydroxy compound is a compound represented by HO-Ar-OH (where Ar is a divalent aromatic residue, for example, phenylene, naphthylene, biphenylene, pyridylene,- Ar ₁ is a divalent aromatic group represented by Ar ₁ —Y—Ar ₂ —, wherein Ar ₁ and Ar ₂ are each independently a divalent carbocyclic or heterocyclic aromatic group having 5 to 70 carbon atoms. And Y represents a divalent alkane group having 1 to 30 carbon atoms.)

In the divalent aromatic groups Ar ₁ and Ar ₂ , 1
One or more hydrogen atoms do not adversely affect the reaction, other substituents, for example, 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, It may be substituted by a cyano group, an ester group, an amide group, a nitro group or the like.

Preferred specific examples of the heterocyclic aromatic group include an aromatic group having one or more ring-forming nitrogen, oxygen or sulfur atoms. The divalent aromatic groups Ar ₁ and Ar ₂ represent groups such as substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and substituted or unsubstituted pyridylene. The substituent here is as described above.

The divalent alkane group Y is, for example,
Is an organic group represented by

[0021]

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(Wherein R ₁ , R ₂ , R ₃ and R ₄ each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms,
A cycloalkyl group having 5 to 10 ring carbon atoms, a carbocyclic aromatic group having 5 to 10 ring carbon atoms, and a carbocyclic aralkyl group having 6 to 10 carbon atoms. k is 3 to 1
Represents an integer of 1, R ₅ and R ₆ are individually selected for each X, independently of each other, represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and X represents carbon. R ₁ , R ₂ ,
In R ₃ , R ₄ , R ₅ , and R ₆ , other substituents such as a halogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms are provided as long as one or more hydrogen atoms do not adversely affect the reaction. 1
It may be substituted with 0 alkoxy group, phenyl group, phenoxy group, vinyl group, cyano group, ester group, amide group, nitro group and the like. Examples of such a divalent aromatic group Ar include those represented by the following formula (2).

[0023]

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(Wherein R ₇ and R ₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a cycloalkyl having 5 to 10 ring carbon atoms) An alkyl group or a phenyl group, m and n
Is an integer of 1 to 4, and when m is 2 to 4, each R ₇ may be the same or different, and n is 2 to 4
In this case, each R ₈ may be the same or different. In addition, the divalent aromatic group Ar is represented by -Ar ₁ -Z-Ar _2-
May be indicated.

(Wherein Ar ₁ and Ar ₂ are as described above, and
Is a single bond or -O-, -CO-, -S-, -SO2-,
-SO -, - COO -, - CON (R 1) - represents a divalent group, such as. Here, R ₁ is as described above. Examples of such a divalent aromatic group Ar include those represented by the following formula (3).

[0026]

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(Wherein R ₇ , R ₈ , m and n are as described above). The aromatic dihydroxy compound used in the present invention may be used alone or in combination of two or more. May be. A typical example of the aromatic dihydroxy compound is bisphenol A.
It is preferable to use 5% or more. It is preferable that these aromatic dihydroxy compounds have a small content of a chlorine atom and an alkali or alkaline earth metal, and it is preferable that they are not substantially contained if possible.

The carbonic diester used in the present invention is represented by the following chemical formula 4.

[0029]

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(Wherein, Ar_Three, Ar_FourAre monovalent
Represents an aromatic group. ) Ar_ThreeAnd Ar_FourIs a monovalent carbocyclic or heterocyclic aromatic
Represents an Ar group _Three, Ar_FourOne or more water
Other substituents whose elemental atoms do not adversely affect the reaction, for example
For example, a halogen atom, an alkyl group having 1 to 10 carbon atoms,
Alkoxy groups of the formulas 1 to 10, phenyl groups, phenoxy
Group, vinyl group, cyano group, ester group, amide group, nitro
It may be substituted by a group such as b. Ar
_Three, Ar_FourCan be the same or different
May be.

Representative examples of the monovalent aromatic groups Ar ₃ and Ar ₄ include a phenyl group, a naphthyl group, a biphenyl group and a pyridyl group. These may be substituted with one or more substituents described above. Preferred examples of Ar ₃ and Ar ₄ include, for example,

[0032]

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Representative examples of the carbonic acid diester include substituted or unsubstituted diphenyl carbonates represented by the following formula (6).

[0034]

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(Wherein R ₉ and R ₁₀ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms,
An alkoxy group having 10; a cycloalkyl group having 5 to 10 ring carbon atoms; or a phenyl group;
When p is 2 or more, each R9 may be different, and when q is 2 or more,
Each R10 may be different. Among these diphenyl carbonates, unsubstituted diphenyl carbonate, ditolyl carbonate, di-t
Symmetric diaryl carbonates, such as lower alkyl-substituted diphenyl carbonates such as -butylphenyl carbonate, are preferred, with diphenyl carbonate being the simplest diaryl carbonate being particularly preferred.

These carbonic acid diesters may be used alone or in combination of two or more. Further, it is preferable that these diaryl carbonates have a small content of a chlorine atom and an alkali or alkaline earth metal, and it is preferable that they are substantially not contained if possible. The use ratio (charge ratio) of the aromatic dihydroxy compound and the carbonic acid diester varies depending on the type of the aromatic dihydroxy compound and the diaryl carbonate used, the polymerization temperature and other polymerization conditions, and the molecular weight and terminal ratio of the polycarbonate to be obtained. There is no particular limitation. The diaryl carbonate is used in an amount of usually 0.9 to 2.5 mol, preferably 0.1 mol, per 1 mol of the aromatic dihydroxy compound.
It is used in a proportion of 95 to 2.0 mol, more preferably 0.98 to 1.5 mol. The ratio of hydroxy and non-hydroxy ends is controlled in the range of 0/100 to 100/0.

In the present invention, a small amount of an aromatic polyhydroxy compound for introducing a branched structure may be used in combination as long as the object of the present invention is not impaired. An aromatic monohydroxy compound may be used in combination. In the present invention, the transesterification method
A method in which the above compound is subjected to a polycondensation by transesterification in a molten state while heating under reduced pressure or / and an inert gas flow in the presence or absence of a catalyst, and its polymerization method and apparatus are limited. There is no. For example, a stirred tank reactor, a thin film reactor, a centrifugal thin film evaporation reactor, a surface-renewal twin-screw kneading reactor, a twin-screw horizontal stirring reactor, a wet-wall reactor, and a perforated plate that allows free-fall polymerization It can be easily produced by using a reactor, a perforated plate type reactor with a wire that polymerizes while being dropped along the wire, or the like, alone or in combination. Further, after the transesterification reaction is performed in a molten state to produce a prepolymer, the prepolymer can be produced by a solid phase polymerization method in which the degree of polymerization is increased in a solid state under reduced pressure or / and under an inert gas flow. The material of these reactors is not particularly limited, and is usually selected from stainless steel, nickel, glass lining and the like.

The polycarbonate used in the present invention is:
What is necessary is just to manufacture by the above-mentioned transesterification method, and the manufacturing method is not specifically limited. Usually, the transesterification reaction temperature for producing polycarbonate is usually 50
-350 ° C, preferably 100-300 ° C. In general, it is known that at a temperature higher than the above range, the obtained polycarbonate tends to be greatly colored and have poor thermal stability, and at a temperature lower than the above range, the polymerization reaction is slow and not practical. In the present invention, in the transesterification method, it is preferable to produce a polycarbonate by controlling the temperature and the residence time of the polycarbonate during the production within a specific range satisfying the expression (1). If the relationship between the temperature and the residence time is larger than the above range, the mechanical properties such as tensile elongation and IZOD impact strength are unfavorably reduced, and if smaller than the above range, the molding fluidity is undesirably reduced.

[0039] Ti: average temperature of polycarbonate in step i (° C.) Hi: average residence time in step i (hr) ki: coefficient at Ti temperature represented by formula (2) ki = 1 / aTi ^−b (2) When Ti <240 ° C. a = 1.60046 × 10 ⁵ b = 0.472 When 240 ° C. ≦ Ti <260 ° C. a = 4 × 10 ⁴⁹ b = 19.107 When 260 ° C. ≦ Ti a = 1 × 10 ¹²² b = 49.082 In the production of polycarbonate by the transesterification method, it is general to change the temperature, the residence time and the reaction pressure stepwise. The sum of × T × H is shown. For example, 連 続 (ki × Ti ×) in the case where a dissolution mixing tank of an aromatic dihydroxy compound and a carbonic acid diester, a stirring tank type reactor, a centrifugal thin film evaporation reactor and a surface renewal type twin-screw kneading reactor are connected for continuous polymerization. Hi) is (k × T × H in the dissolving / mixing tank) + (k × T × H in the piping from the dissolving / mixing tank to the stirred tank reactor) + (k × T in the stirred tank reactor) × H) + (k × T × H of piping from the stirred tank type reactor to the centrifugal thin film evaporation reactor) + (k × T × H in the centrifugal thin film evaporation reactor) + (centrifugal thin film evaporation reaction) K × T × H) of piping from the vessel to the surface renewal type twin screw kneading reactor
(K × T × H in the surface-renewal type twin-screw kneading reactor) + (k × T × H of the pipe from the surface-renewal type twin-screw kneading reactor to the extraction nozzle), and all stages including the piping Shows the sum of In this case, the i-step refers to each stage or step of each mixing tank or reactor and the piping connecting them.
If there is a heater in the middle of the pipe connecting the reactors, the pipe between the reactor and the heater, the heater, and the pipe between the heater and the reactor are each referred to as an i step. The average temperature of the polycarbonate refers to the average value of the temperatures in the i-th step. If the temperature is clearly divided into several steps, each step is divided and the average temperature in each step is calculated as the i-step. May be used. The average residence time is calculated by (amount of polycarbonate retained in each i-step / amount of passage or withdrawal per hour).

The reaction pressure also depends on the molecular weight of the polycarbonate during melt polymerization. When the number average molecular weight is 1,000 or less, the range of 50 mmHg to normal pressure is generally used, and the number average molecular weight is 1,000 to 2,000. In the range, the range of 3 mmHg to 80 mmHg is 10 mmHg or less when the number average molecular weight is in the range of 2000 or more,
In particular, 5 mmHg or less is used.

The polymerization by the transesterification method can be carried out without adding a catalyst. However, in order to increase the polymerization rate, the polymerization is carried out in the presence of a catalyst if necessary. The polymerization catalyst is not particularly limited as long as it is used in this field, and hydroxides of alkali metals and alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide are used. Alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydrides of boron and aluminum such as lithium aluminum hydride, sodium borohydride, tetramethylammonium borohydride; lithium hydride, sodium hydride ,
Hydrogen compounds of alkali metals and alkaline earth metals such as calcium hydride; alkoxides of alkali metals and alkaline earth metals such as lithium methoxide, sodium ethoxide and calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide; LiO-Ar-OLi, NaO-Ar-ON
aryloxides of alkali metals and alkaline earth metals such as a (Ar is an aryl group); organic acid salts of alkali metals and alkaline earth metals such as lithium acetate, calcium acetate and sodium benzoate; zinc oxide, zinc acetate;
Zinc compounds such as zinc phenoxide; boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, (R ₁ R ₂ R ₃ R ₄ ) NB (R ₁ R ₂ R ₃ R
₄ ) or (R ₁ R ₂ R ₃ R ₄ ) PB (R ₁ R ₂ R ₃ R ₄ ) represented by ammonium borates or phosphonium borates (R ₁ ,
R ₂ , R ₃ and R ₄ are as described in the above formula 3), etc .; boron oxides such as silicon oxide, sodium silicate, tetraalkylsilicon, tetraarylsilicon, diphenyl-ethyl-
Silicon compounds such as ethoxysilicon; germanium oxide, germanium tetrachloride, germanium ethoxide,
Germanium compounds such as germanium phenoxide; tin compounds such as tin compounds and organotin compounds combined with an alkoxy or aryloxy group such as tin oxide, dialkyltin oxide, dialkyltin carboxylate, tin acetate, and ethyltin tributoxide ;
Lead compounds such as lead oxide, lead acetate, lead carbonate, basic carbonate, alkoxide or aryloxide of lead and organic lead; onium compounds such as quaternary ammonium salt, quaternary phosphonium salt and quaternary arsonium salt Antimony compounds such as antimony oxide and antimony acetate;
Manganese compounds such as manganese acetate, manganese carbonate and manganese borate; titanium compounds such as titanium oxide, titanium alkoxide or aryloxide; zirconium compounds such as zirconium acetate, zirconium oxide, zirconium alkoxide or aryloxide, zirconium acetylacetone And the like.

When a catalyst is used, these catalysts may be used alone or in combination of two or more. The amount of these catalysts to be used is generally selected in the range of 10 ^-8 to 1% by weight, preferably 10 ^-7 to 10 ^-1 % by weight, based on the aromatic dihydroxy compound as the raw material. Although the molecular weight of the polycarbonate used in the present invention is not particularly limited, it is generally 1000 to 30 in weight average molecular weight.
000, preferably 5000 to 1000
00, particularly preferably 12000 to 800
00 range. Also, the terminal structure is not particularly limited.

The polycarbonate used in the present invention is:
When completely hydrolyzed and has a retention time after the aromatic dihydroxy compound used, that is, a small amount of a bond estimated to be a moderate heterogeneous bond, as measured by reverse phase liquid chromatography, It is excellent in color tone and mechanical properties, has higher non-Newtonian flow behavior than phosgene method polycarbonate, and is excellent in molding fluidity, and can be used for a wide range of applications. In that case, if necessary, heat stabilizers, antioxidants, weathering agents, release agents, lubricants, antistatic agents, plasticizers, polymers such as other resins and rubbers, pigments, dyes, fillers, A reinforcing agent, a flame retardant and the like may be added and used. Further, these additives and the like may be added while the polycarbonate-based resin after the polymerization is in a molten state, or after the polycarbonate is once pelletized, the additives may be added and re-melted and kneaded. In particular, since the polycarbonate causes an oxidation reaction by heat and is colored, it is particularly preferable to add an antioxidant in advance. Examples of the antioxidant include a phosphorus compound and a phenol compound. Examples of the phosphorus compound include tris (nonylphenyl) phosphite, triphenylphosphite, tris (ethylphenyl) phosphite,
Tris (butylphenyl) phosphite, tris (hydroxyphenyl) phosphite, tetrakis (2,4-
Di-t-butylphenyl) -4,4′-biphenylenediphosphite, tris (2,4-di-t-butylphenyl) phosphite and the like. Examples of the phenolic compound include octadecyl-3-phosphate. (3'-5'-
Di-t-butyl-4-hydroxyphenyl) propionate, tetrakismethylene (3,5-di-t-butyl-
4-hydroxyhydrocinnamate) methane, 2,2-
Thio [diethylbis-3 (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate, 2,6-di-
t-butyl-4-methylphenol, 2-t-butyl-
6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 4,4 ′
-Butylidenebis (3-methyl-6-t-butylphenol), alkylated bisphenol and the like.

The ultraviolet absorber used in the present invention includes an ultraviolet absorber composed of a benzotriazole compound, a benzophenone compound, a hydroxyphenyltriazine compound, a salicylic acid phenyl ester compound, or the like. As the benzotriazole-based compound, 2- (5
-Methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-5 '-T-octylphenyl) benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetramethylenebutyl) -6- (2H-benzotriazol-2-yl) phenol], and the like. Benzophenone-based compounds include 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4′-chlorobenzophenone,
2,2-dihydroxy-4-methoxybenzophenone,
2,2-dihydroxy-4,4'-dimethoxybenzophenone and the like.

Examples of the ultraviolet absorber comprising a hydroxyphenyltriazine compound include, for example, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine and 2,4-diphenyl −
6- (2-hydroxy-4-ethoxyphenyl) -1,
3,5-triazine, 2,4-diphenyl-6- (2-
(Hydroxy-4-propoxyphenyl) -1,3,5-
Triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-
Hexyloxyphenyl) -1,3,5-triazine,
2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine,
4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-
Diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4- (2-butoxyethoxy) phenyl) -1, 3,5-triazine, 2,4
-Di-p-toluyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-di-p-toluyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-di-p
-Toluyl-6- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-di-p-
Toluyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-di-p-toluyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3 , 5-Triazine, 2,4-di-p-toluyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-di-p-
Toluyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-di-p
-Toluyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-di-
p-toluyl-6- (2-hydroxy-4- (2-hexyloxyethoxy) phenyl) -1,3,5-triazine and the like; and para-t-butyl as a salicylic acid phenyl ester ultraviolet absorber. Examples include phenylsalicylate and para-octylphenylsalicylate.

Of these, ultraviolet absorbers composed of benzotriazole-based compounds and hydroxyphenyltriazine-based compounds, which are more difficult to volatilize, are more preferable. The blending amount of the ultraviolet absorber in the polycarbonate sheet is 0.01
-20% by weight, more preferably 0.02-1% by weight.
5% by weight. When the amount is less than 0.01% by weight, the weather resistance effect is small. On the contrary, when the amount exceeds 20% by weight, the polycarbonate sheet itself is colored, which is a problem in a polycarbonate sheet characterized by transparency.

There is no limitation on the method of blending the ultraviolet absorber with the polycarbonate. For example, a method of adding and blending an ultraviolet absorber in the polymerization process of polycarbonate, a method of dry-blending the polycarbonate and the ultraviolet absorber, followed by an extruder, and a method of kneading under heating and melting,
A method in which an ultraviolet absorber is side-fed during the molding of the polycarbonate sheet can be used.

The method for forming the polycarbonate sheet is not limited, and it can be formed by an extrusion method, a press molding method, an injection molding method, or the like. However, an extrusion method capable of continuously forming a sheet of uniform quality is preferable. . In the extrusion molding method, a powdery or pelletized polycarbonate raw material is heated, melted and kneaded in a molding machine by an extrusion molding method, extruded into a sheet shape through a T-die or the like, and then cooled and solidified using two to four polishing rolls. This is a method of making a sheet. At this time, the resin temperature of the polycarbonate discharged from the molding machine is preferably adjusted to 240 to 290 ° C, more preferably 260 to 280 ° C. 24
If the resin temperature is lower than 0 ° C., the load on the molding machine is significantly increased and molding cannot be performed. Conversely, if the resin temperature is higher than 290 ° C., the ultraviolet absorber volatilizes during molding, and coloring or hydrolysis due to heat, etc. Problems occur. The temperature of the resin discharged from the molding machine can be adjusted during molding by the molding machine heating cylinder temperature and screw rotation speed.
It can also be adjusted by changing the screw shape such as D, compression ratio, kneading zone and the like.

In order to form a transparent sheet, it is preferable that hard chrome plating or the like is applied to portions of the molding machine such as cylinders and screws, polishing rolls and guide rolls which are in direct contact with polycarbonate.
The polycarbonate sheet referred to in the present invention may be a single-layer sheet made of the above-mentioned polycarbonate alone or a laminated sheet obtained by stacking a plurality of resins containing the above-mentioned polycarbonate. As a laminated sheet, for example, the surface of the weatherable polycarbonate sheet of the present invention is coated with an acrylic resin or another polycarbonate resin, a silicone resin, a fluororesin, or the like by a coating method, a film laminating method, a coextrusion method, or the like. Examples include a laminated sheet which is stacked, and a sheet obtained by laminating the weather-resistant polycarbonate sheet of the present invention on an acrylic resin or another polycarbonate resin.

The weather-resistant polycarbonate sheet of the present invention can be subjected to secondary processing such as thermoforming, cutting, bonding, cold bending, printing and the like, similarly to a commercially available weather-resistant polycarbonate sheet. In particular, in thermoforming, the weatherable polycarbonate sheet of the present invention can be molded at a lower temperature than commercially available sheets, so that there is almost no loss of the ultraviolet absorber incorporated in the sheet, and it has excellent weatherability even after thermoforming. The thermoforming here means that the polycarbonate sheet is heated and softened and formed into a specific shape.For example, heat bending, heating curved surface forming, free blow molding, pressure forming, vacuum forming, free press forming, Examples include plug-assist vacuum forming, drape forming, vacuum snap-back forming, and reverse draw forming.

The thickness of the weather-resistant polycarbonate sheet in the present invention can be freely designed within the range of 1 to 20 mm.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The effects of the present invention will be more specifically described below with reference to examples and comparative examples. The evaluation of each item was measured by the following method. In addition, the complete hydrolysis of the polycarbonate and the measurement method of liquid chromatography were performed by the methods described in the specification. (1) Measurement of weight average molecular weight.

The measurement was performed by gel permeation chromatography (GPC). (2) Measurement of ultraviolet absorber concentration in polycarbonate sheet. The test piece was dissolved in chloroform, and subjected to structural analysis by high performance liquid chromatography (model LC-6A, manufactured by Shimadzu Corporation) to determine the spectral peak area of the ultraviolet absorber structure portion. From the calibration curve, the residual concentration of the ultraviolet absorber contained in the polycarbonate sheet was determined.

(3) Weather Resistance Using Sunshine Super Long Life Carbon with a sunshine weather meter manufactured by Suga Test Instruments, and using a temperature of 6
The test piece was exposed for 1000 hours under the condition of repeating a cycle of 2 hours without rainfall and 18 minutes of rainfall at a constant 3 ° C.

As the evaluation, the change in yellowness before and after exposure was evaluated as J.
It was measured according to IS K 7103. Yellowing degree (ΔYI) = (yellowness before exposure) − (yellowness before exposure) When the value of yellowing degree (ΔYI) is large, the yellowness becomes deeper as a result of the weather resistance test as compared to the initial value ( When the yellowing degree exceeds 4, it is clearly visible that the pigment is colored.

[0056]

Example 1 Stirred tank type first (A) and (B) polymerization vessels, stirred tank type second polymerization vessel, stirred tank type third polymerization vessel, perforated plate type first polymerization vessel, and perforated plate type second polymerization vessel Is a continuous process
An aromatic polycarbonate was produced. However, the first stirring tank
The polymerization reactor was operated batchwise while switching between (A) and (B), and the other polymerization reactors were continuously operated. Stirring tank first
The internal volumes of the polymerization vessels (A) and (B) are 100 liters, the internal volumes of the second polymerization vessel and the third polymerization vessel of the stirring vessel are 50 liters, and both the stirring blades are anchor type. The perforated plate type first polymerization vessel and the perforated plate type second polymerization vessel have a pore size of 7.
A perforated plate having 50 5 mm holes is provided, and a 1 mm diameter SUS316L wire-shaped guide penetrates each hole. The height to drop along the guide is 8
m. Further, each reactor was arranged such that the length and thickness of a pipe connecting each reactor was minimized.

The temperature of the first polymerization vessel in the stirring tank (A) and (B) is 180 ° C., normal pressure, and the flow rate of the sealing nitrogen gas is 1 liter / hr. Stirring tank first polymerization vessel (A)
80 kg of bisphenol A as an aromatic dihydroxy compound and diphenyl carbonate as a carbonate diester (molar ratio to bisphenol A 1.04) were further charged, and bisphenol A disodium salt was charged as a sodium atom, and 20 ppb with respect to bisphenol A.
And melt-mixed for 4 hours.
At hr, the mixture was continuously supplied to the second polymerization vessel in the stirring tank. Stirring tank first
While feeding from the polymerization vessel (A) to the second polymerization vessel in the stirring vessel, the first polymerization vessel (B) in the stirring vessel is charged with bisphenol A, diphenyl carbonate and bisphenol in the same manner as in the first polymerization vessel (A). The disodium A salt was melt-mixed, and when the first polymerization vessel (A) of the stirring tank became empty, the polymerization vessel was switched to the first polymerization vessel (B) of the stirring tank. Thereafter, in the same manner, the first polymerization reactor (A) and (B) in the stirring tank were switched in batches, and the polymerization intermediate was continuously fed to the second polymerization reactor in the stirring tank at 5 kg / h.
The supply was continued at r.

When the content of the second polymerization vessel in the stirring tank reached 20 liters, the polymerization intermediate was continuously supplied to the third polymerization vessel in the stirring vessel so as to keep the content of 20 liters constant. The second polymerization vessel in the stirring tank has a reaction temperature of 230 ° C. and a reaction pressure of 100 mm.
Hg and nitrogen gas flow rate were 2 liter / hr.
When the content of the third polymerization vessel in the stirred tank reaches 20 liters,
The polymerization intermediate was continuously supplied to the perforated plate-type first polymerization vessel so as to keep the content of 20 liters constant. The third polymerization vessel in the stirring tank had a reaction temperature of 240 ° C., a reaction pressure of 10 mmHg, and a nitrogen gas flow rate of 2 liter / hr.

When the content of the first perforated plate type polymerization vessel reached 10 liters, the polymerization intermediate was continuously supplied to the second perforated plate type polymerization vessel so as to keep the content volume constant at 10 liters. The perforated plate type first polymerization reactor had a reaction temperature of 245 ° C and a reaction pressure of 1.
The conditions were 5 mmHg and a nitrogen gas flow rate of 4 liter / hr. When the internal volume of the perforated plate type second polymerization vessel reached 10 liters, the molten polymer was continuously withdrawn from the nozzle so as to keep the internal volume constant at 10 liters, and pelletized by strand cutting. The perforated plate-type second polymerization vessel has a reaction temperature of 2
The conditions were 45 ° C., a reaction pressure of 0.3 mmHg, and a nitrogen gas flow rate of 2 liter / hr. Σ (Ki × Ti
× Hi) was 0.83.

In the polycarbonate thus obtained, the total amount of compounds having a retention time longer than that of bisphenol A was 0.05% by weight, and the total amount A of the compounds having a retention time between bisphenol A and diphenyl carbonate was 0.05% by weight. (However, the ratio B / A between the other aromatic dihydroxy compound used and diphenyl carbonate) and the total amount B of the compound after diphenyl carbonate (however, excluding the other aromatic dihydroxy compound used and diphenyl carbonate) Was 0.2. The weight average molecular weight of the polycarbonate was 26,800.

99.9% by weight of the polycarbonate and 2-
(4,6-diphenyl-1,3,5-triazine-2-
Dry-blended 0.1% by weight of a UV absorber made of a hydroxyphenyltriazine-based compound consisting of yl) -5- (hexyl) oxy-phenol was heated and melt-kneaded through an extruder having a screw diameter of 50 mm, and the width was 300.
The sheet was extruded into a sheet shape using a sheet die having a thickness of 1 mm. Next, a sheet-like molten polycarbonate was prepared with a diameter of 200 mm.
And cooled and solidified to obtain a polycarbonate sheet.

At this time, the temperature of the resin discharged from the extruder was adjusted to about 260 ° C., the temperature of the die was adjusted to 250 ° C., and the surface temperature of the polishing roll was adjusted to 130 ° C. The thickness of the sheet was adjusted to 3 mm by controlling the gap between the polishing rolls. When the concentration of the ultraviolet absorbent remaining in the polycarbonate sheet thus obtained was measured, it was 0.09% by weight, and it was found that there was almost no loss of the ultraviolet absorbent during sheet extrusion.

The polycarbonate sheet was subjected to a weather resistance test. As a result, it was found that the yellowing degree (ΔYI) was 1 and the weather resistance was good. As a result of performing vacuum press molding using the obtained polycarbonate sheet,
There was almost no loss of the ultraviolet absorber due to the thermoforming, the weather resistance was good even after the thermoforming, and the same performance as before the thermoforming.

[0064]

Example 2 An ultraviolet absorber to be added to polycarbonate was prepared from 2,2-methylenebis [4- (1,1,3,3-tetramethylenebutyl) -6- (2H-benzotriazol-2-yl) phenol]. The procedure was performed in the same manner as in Example 1 except that the product was changed to a benzotriazole-based compound.

When the concentration of the ultraviolet absorber remaining in the polycarbonate sheet thus obtained was measured, it was found to be 0.09% by weight, indicating that there was almost no loss of the ultraviolet absorber during sheet extrusion. As a result of a weather resistance test of this polycarbonate sheet, the yellowing degree (ΔY
I) was 1, and the weather resistance was found to be as good as in Example 1.

Further, as a result of performing vacuum press molding using the obtained polycarbonate sheet, almost no loss of the ultraviolet absorber due to thermoforming was obtained as in Example 1, the weather resistance was good even after thermoforming, and the heat resistance was unchanged. It was the same performance.

[0067]

Embodiment 3 The temperature of the resin discharged from the extruder is 250
The procedure was carried out in the same manner as in Example 1 except that the molding conditions were adjusted to be ℃. As for the state of the extrusion molding, the load of the extruder was slightly increased, but the sheet molding itself could be performed without any problem.
The concentration of the ultraviolet absorbent remaining in the polycarbonate sheet thus obtained was measured.
It was found that there was almost no loss of the ultraviolet absorbent during sheet extrusion as in Example 1.

As a result of a weather resistance test of this polycarbonate sheet, it was found that the yellowing degree (ΔYI) was 1, and the weather resistance was also good. In addition, as a result of performing vacuum press molding using the obtained polycarbonate sheet, there was almost no loss of the ultraviolet absorber due to thermoforming as in Example 1, and the weatherability was good even after thermoforming, and the same performance as before thermoforming. there were.

[0069]

Comparative Example 1 The temperature of each reactor was changed, and the total amount of the compound having a retention time longer than that of bisphenol A was 0.1%.
5% by weight, retention time is bisphenol A
Total amount A of the compound between the diphenyl carbonate and
(However, the ratio B / A between the other aromatic dihydroxy compound used and diphenyl carbonate) and the total amount B of the compound after diphenyl carbonate (however, excluding the other aromatic dihydroxy compound used and diphenyl carbonate) Is 0.
The evaluation was performed in the same manner as in Example 1 except that the polycarbonate adjusted to 95 was used. The weight average molecular weight of the polycarbonate at this time was 26,900.

However, when molding was performed under the same molding conditions as in Example 1, the load on the extruder increased, and overloading was repeatedly stopped, so that molding could not be performed stably. When the molding conditions were adjusted so that the load of the extruder was almost the same as in Example 1, the temperature of the resin discharged from the extruder became 295 ° C. The concentration of the ultraviolet absorbent remaining in the polycarbonate sheet obtained by molding the sheet under the condition that the load of the extruder was almost the same as that of Example 1 was 0.06% by mass. It can be seen that the absorbent has decreased.

When a weather resistance test was performed on this polycarbonate sheet, the yellowing degree (ΔYI) was 4,
It was found that the effect of blending the ultraviolet absorber was reduced. In addition, as a result of performing vacuum press molding using the obtained polycarbonate sheet in the same manner as in Example 1, volatilization and loss of the ultraviolet absorber occurred during heating and softening, and the volatilized ultraviolet absorber adhered to the press die. Surface is rough,
Further, the weather resistance was further deteriorated as compared with that before the thermoforming.

[0072]

Comparative Example 2 A commercial polycarbonate produced by the phosgene method and having a weight average molecular weight of 26,800 was evaluated in the same manner as in Example 1. Also in this case, if the molding is performed under the molding conditions as in Example 1, the load of the extruder increases and the overload is stopped, so that the molding cannot be performed stably. When the molding conditions were adjusted so that the load of the extruder was approximately the same as in Example 1, the temperature of the resin discharged from the extruder became 300 ° C.

The concentration of the ultraviolet absorbent remaining in the polycarbonate sheet obtained by forming the sheet under the condition that the load of the extruder was almost the same as that of Example 1 was measured.
It can be seen that the amount of the ultraviolet absorbent was reduced during sheet extrusion molding. When a weather resistance test was performed on this polycarbonate sheet, the yellowing degree (ΔY
As for I), there were 6 and it was found that there was almost no effect of blending the ultraviolet absorber.

The obtained polycarbonate sheet was subjected to vacuum press molding in the same manner as in Example 1. As a result, as in Comparative Example 1, volatilization and loss of the ultraviolet absorbent occurred during softening by heating. Due to the adhesion to the press die, the surface of the molded body was roughened, and the weather resistance was further deteriorated as compared with that before the thermoforming.

[0075]

[Table 1]

[0076]

According to the present invention, there is provided a polycarbonate sheet which maintains weather resistance even after secondary processing such as thermoforming, and a method for producing the weather resistant polycarbonate sheet which prevents loss of an ultraviolet absorber generated during molding. And can be used for a wider range of applications.

[0077]

[Brief description of the drawings]

[0078]

FIG. 1 is a liquid chromatography chart of a standard compound mixture measured by the method described in the specification.

[0079]

FIG. 2 is a liquid chromatography chart of a completely hydrolyzed polycarbonate measured by the method described in the specification.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08K 5/3492 C08K 5/3492 // B29K 69:00 B29L 7:00

Claims (7)

[Claims] 1. A weather-resistant polycarbonate sheet comprising a small amount of a polycarbonate having a heterogeneous bond and containing an ultraviolet absorber in an amount of 0.01 to 20% by weight. 2. A polycarbonate having a small amount of a heterogeneous bond is a polycarbonate produced by transesterification from an aromatic dihydroxy compound and a carbonic acid diester, and the polycarbonate is completely hydrolyzed and then subjected to reverse phase liquid chromatography. When using a mixed eluent composed of methanol and 0.1% phosphoric acid aqueous solution and measuring the ratio of methanol / 0.1% phosphoric acid aqueous solution from 20/80 to a gradient of 100/0, The total amount of compounds having a retention time longer than that of the aromatic dihydroxy compound (the amount calculated from the peak area using the extinction coefficient of salicylic acid, detected by a UV detector having a wavelength of 300 nm, except for the carbonic acid diester),
0.01 to 0.10% by weight based on the polycarbonate
The weather-resistant polycarbonate sheet according to claim 1, which is a polycarbonate in the range described above. 3. 85 mol% of the aromatic dihydroxy compound
3. The weather-resistant polycarbonate sheet according to claim 1, wherein the above is bisphenol A. 4. A retention time of bisphenol A
Total amount A of the compound between the diphenyl carbonate and
(However, the ratio B / A between the other aromatic dihydroxy compound used and diphenyl carbonate) and the total amount B of the compound after diphenyl carbonate (however, excluding the other aromatic dihydroxy compound used and diphenyl carbonate) But,
The weatherable polycarbonate sheet according to any one of claims 1 to 3, wherein the thickness is 0.8 or less. 5. The weatherable polycarbonate sheet according to claim 1, wherein the ultraviolet absorber comprises a benzotriazole compound. 6. The weatherable polycarbonate sheet according to claim 1, wherein the ultraviolet absorber comprises a hydroxyphenyltriazine compound. 7. The molding of the weather-resistant polycarbonate sheet according to claim 1, wherein the resin temperature of the polycarbonate sheet raw material composition comprising a small amount of a polycarbonate having a heterogeneous bond is adjusted to 240 to 290 ° C. A method for producing a weather-resistant polycarbonate sheet, characterized by extruding.