JPH07107100B2 - Method for producing polycarbonate-based copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polycarbonate-based copolymer which has a small stress optical coefficient and is suitable for use as an optical molded article.

[Prior Art and Its Problems] Polycarbonate resins are widely used as industrial materials because they have high mechanical strength, high heat resistance, and good transparency. Among them, many attempts have been made to utilize the good transparency for use in optical materials.

However, when a polycarbonate resin is used as an optical material, it has a drawback that a product obtained by injection molding or melt spinning has a large birefringence due to molecular orientation because of its large stress optical coefficient.

[Problems to be Solved by the Invention] An object of the present invention is to produce a polycarbonate-based copolymer having a small stress optical coefficient and to provide a resin material suitable for an optical material.

That is, the object of the present invention is to provide a method for producing a novel polycarbonate-based copolymer having a small stress optical coefficient while maintaining excellent properties of polycarbonate such as transparency, surface hardness, heat resistance, and mechanical properties. To provide.

[Means for Solving Problems] The present inventors have found that when a component having a bulky structure is introduced into a polymer main chain as a graft or as an end group, the molecular orientation of the polycarbonate resin at the time of molding is lowered. Therefore, the present invention has been accomplished by finding that the object can be achieved by selecting a specific styrene-based oligomer as the bulky component.

That is, the present invention is selected from (A) (a) styrene-based monomers, thiomalic acid, thioglycolic acid, 2-aminoethanethiol, 2-mercapto-1,4-butanedicarboxylic acid and salts thereof. Polycondensation of a propolymer obtained by reacting at least one chain transfer agent, a styrene-based macromonomer obtained by the reaction with a polymerization initiator, and (b) a polycarbonate oligomer, and (B) an aromatic dioxy compound The present invention provides a method for producing a polycarbonate-based copolymer, which comprises:

The styrenic macromonomer used in the present invention is obtained by polymerizing a styrenic monomer with a degree of polymerization of 10 to 100, and has a functional group (-COOH, -OH, -NH) capable of being acylated at one end by the Schotten-Baumann reaction. ₂ etc.).

Examples of the styrene-based macromonomer include styrene and α
-Methylstyrene, p-methylstyrene, p-tert-butylstyrene, and other styrene-based monomer-containing styrene molecular structures are dissolved in a solvent, and a predetermined chain transfer agent and polymerization initiator are added to the mixture at a temperature of 40 to 70 ° C. Reaction for 0.5 to 5 hours, and then the product is poured into a precipitating agent to cause precipitation, which is separated by filtration,
It can be produced by drying and refining.

The chain transfer agent used in this reaction is at least one selected from thiomalic acid, thioglycolic acid, 2-aminoethanethiol, 2-mercapto-1,4-butanedicarboxylic acid and salts thereof. is necessary.

As the polymerization initiator, for example, azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide and the like can be preferably used.

As the solvent used in this production method, any solvent can be used, for example, a polar solvent such as tetrahydrofuran or dimethylformamide, benzene, toluene,
An aromatic hydrocarbon solvent such as xylene, an aliphatic hydrocarbon solvent such as hexane, heptane, or octane, a mixed solvent of the aromatic hydrocarbon solvent and the aliphatic hydrocarbon solvent, and the like can be used. Among these, preferred solvents are polar solvents such as tetrahydrofuran.

Further, as the precipitant, for example, petroleum ether,
Aromatic hydrocarbons such as benzene and aliphatic alcohols such as methanol and ethanol can be used.

As the styrenic macromonomer of the present invention, for example, when thiomalic acid is used as a chain transfer agent, the following formula is obtained.

(R ² is a monomer unit of a styrenic compound, m is a degree of polymerization) Similarly, when thioglycolic acid is used as a chain transfer agent, the following formula is obtained.

Those with ^{_{HOOC-CH 2 -S- (R 2}} ) m-H (II) styrenic macromonomer polyfunctional chain transfer agents are also those with three or more acylating possible functional groups of the present invention You can get it if you choose.

The polycarbonate oligomer used in the present invention is, for example, an aromatic dioxy compound such as bis-2- (4-hydroxyphenyl) -propane dissolved in an aqueous solution of caustic soda, an organic solvent such as methylene chloride, and phosgene therein while stirring the mixture. Blow-in and stop the introduction of phosgene when the pH is in the range of 9 to 12, and the aqueous layer and the organic layer are allowed to stand and separate to obtain a solvent solution.

At this time, the molecular weight of the oligomer and the ratio of the hydroxyl group and the chloroformate group in the molecule can be arbitrarily adjusted by appropriately controlling the reaction conditions.

As the polycarbonate oligomer used in the method of the present invention, those having a degree of polymerization of 2 to 50, preferably 3 to 10 can be used, and those having a terminal chloroformate group content of 65% or more can be used. it can. When the polymerization degree of this polycarbonate oligomer is less than 2, the mechanical strength of the finally obtained polycarbonate-based copolymer may be insufficient, and when the polymerization degree is more than 50, the polycarbonate-based copolymer The moldability of the polymer may deteriorate. When the content of the terminal chloroformate group in the polycarbonate oligomer is less than 65%, the prepolymer formation reaction may not proceed sufficiently.

In addition to bisphenol A, for example, bis-2- (4-hydroxyphenyl) -propane and bis- (4 as an aromatic dioxy compound used in the production of the propolymer of the present invention and polycondensation with the prepolymer. -Hydroxyphenyl) -methane, bis-2- (4-hydroxy-3,5
-Dimethylphenyl) -propane, bis-1- (4-hydroxyphenyl) -butane, bis- (3- (4-hydroxyphenyl) -pentane, bis-1- (4-hydroxyphenyl) -cyclohexane and other bis- (4-Hydroxyphenyl) -alkane, 2,2- (3,5,3 ', 5'
-Tetrachlor-4,4'-dihydroxyphenyl) -propane, 2,2- (3,5,3 ', 5'-tetrabromo-4,4'-
Dihydroxydiphenyl) -propane, 2,2- (3,3'-
Dichloro-4,4-dihydroxydiphenyl) -propane, 2,2- (3,5-dichloro-4,4'-dihydroxydiphenyl) -propane, 2,2- (3,3'-dichloro-5,5 '
-Dimethyl-4,4'-dihydroxydiphenyl) -propane, 2,2- (3,3'-diprom-4,4-dihydroxyphenyl) -propane, 3,5,3 ', 5'-tetrabromo-4, Four
-Halogen-containing bisphenols such as dihydroxydiphenyl sulfone, or 4,4-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl, 4,
One or more of bisphenols such as 4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxydiphenyl ether and hydroquinone are preferably used. In the method of this invention, bisphenol A is usually the most commonly used dioxy compound.

The prepolymer in the present invention can be synthesized by reacting the styene-based macromonomer with the polycarbonate-based oligomer. The synthesis reaction of this prepolymer is a polycondensation reaction, and can be carried out, for example, in the presence of a catalyst in an organic solvent capable of dissolving the polycarbonate oligomer and the resulting prepolymer.

As the catalyst in this case, tertiary amines such as trimethylamine, triethylamine, tripropylamine and tributylamine are preferably used. The reaction proceeds even with a quaternary ammonium salt, but the reaction rate becomes very slow.

In addition, in the condensation reaction, a molecular weight modifier may be used in combination, if necessary.

As the solvent, chlorinated hydrocarbons such as tetrachloroethane, trichloroethane, dichloroethane, trichloroethylene, dichloroethylene, chloroform, methylene chloride, chlorobenzene, dichlorobenzene, etc., cyclic oxy compounds such as dioxane, tetrahydrofuran and crown ethers. A compound or the like is used. Furthermore, if necessary, it is preferable to add an antioxidant such as hydrosulfite.

When the prepolymer of the present invention is synthesized from the styrenic macromonomer of the formula I and a polycarbonate oligomer having a degree of polymerization of n, a prepolymer represented by the following formula is obtained.

In this case, the structure is such that the styrene macromonomer is grafted to the polycarbonate chain.

When the prepolymer of the present invention uses, for example, a styrenic macromonomer of the formula II, a styrenic macromonomer bound to the terminal is obtained as follows.

In the method of the present invention, a polycarbonate-based copolymer is produced by polycondensing the prepolymer thus obtained and an aromatic dioxy compound.

As the aromatic dioxy compound used for producing the polycarbonate-based copolymer, the same aromatic dioxy compound used for obtaining the polycarbonate oligomer used for synthesizing the prepolymer can be used. . Different aromatic dioxy compounds used in synthesizing the prepolymer and aromatic dioxy compounds used in producing the polycarbonate-based copolymer can be used.

In the present invention, when a prepolymer of the type of formula III is used, it is polycondensed with an aromatic dioxy compound to form a link between the two prepolymers so that the aromatic dioxy compound enters, and this is repeated one after another. The prepolymers are bound to each other, so that a graft copolymer having a structure in which a styrene-based macromonomer is branched into units of the prepolymer in a main chain mainly composed of a polycarbonate chain is finally obtained. When a prepolymer of the formula IV type is used, it becomes a block copolymer in which styrene-based oligomers are bonded to both ends of the polymer. In this case, the polycarbonate oligomer may be added to the polycondensation system in order to increase the molecular weight. If a styrene-based macromonomer synthesized by using a chain transfer agent having three or more functional groups is partially added to the above prepolymer, the copolymer of the present invention becomes a star polymer type.

It is also possible to use a mixture of the formula III type prepolymer and the formula IV type prepolymer.

According to the production method of the present invention, the type of prepolymer classified by the number of acylatable functional groups of the chain transfer agent used, the type of aromatic dioxy compound, the polymerization degree of the polycarbonate oligomer in the prepolymer, or the like. By selecting the degree of polymerization of the styrene-based macromonomer and the ratio of use thereof, copolymer polymers of various forms can be appropriately designed and synthesized according to the application.

The polycondensation reaction to obtain the copolymer of the present invention is carried out by adding an alkaline aqueous solution of an aromatic dioxy compound to an organic solvent solution of the prepolymer, and if necessary, a catalyst and a molecular weight modifier.
While stirring and cooling, the polycondensation reaction can be carried out at the interface between the organic solvent solution and the aqueous solution.

In the polycondensation reaction for obtaining the copolymer of the present invention, as a catalyst optionally used, a tertiary amine or the like can be basically used as in the case of synthesizing the prepolymer. .

Examples of the molecular weight regulator used in the polycondensation reaction for obtaining the copolymer of the present invention include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and butyl alcohol, phenols such as phenol, cresol and p-tert-butylphenol. Carboxylic acids such as propionic acid, butyric acid, acetic acid and benzoic acid are suitable.

When the obtained organic solvent solution of the copolymer is washed with water to remove inorganic substances and a precipitating agent is added, the copolymer powder is precipitated.

As the precipitating agent at this time, pentane, hexane, heptane, aliphatic hydrocarbons such as cyclohexane, aliphatic alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol, acetone,
Aliphatic ketones such as methyl ethyl ketone may be used alone or in admixture of two or more.

The polycarbonate-based copolymer obtained by the method of the present invention contains a styrene-based resin component in an amount of 5 to 95% by weight, preferably
Contains 10 to 85% by weight, 95 to 5 of polycarbonate component
% By weight, preferably 90 to 15% by weight, and has a weight average molecular weight of 3,000 to 100,000, preferably 5,000 to 50,00.
It is preferably 0. When the amount of the styrene resin component is less than 5% by weight, the stress optical coefficient of the molded article obtained by molding the polycarbonate copolymer is large, and when it is more than 95% by weight, the polycarbonate copolymer is molded. The mechanical strength and heat resistance of the molded product may be insufficient. When the weight average molecular weight is less than 3,000, mechanical strength and heat resistance are lowered, and when it exceeds 100,000, fluidity is lowered and molding may be difficult.

The polycarbonate-based copolymer obtained in this manner maintains the preferred physical properties of the polycarbonate resin, the molecular orientation during molding is lowered, and the stress optical coefficient is small.

EFFECTS OF THE INVENTION According to the production method of the present invention, it is possible to produce an optical material having a reduced stress optical coefficient while maintaining excellent physical properties of polycarbonate such as mechanical strength, heat resistance and transparency. Since the branch component and the terminal component can be appropriately selected, and further, the molecular weight of the copolymer, or the graft ratio, the length of the branch, the length of the terminal group, etc. can be easily controlled appropriately, the present invention There is an advantage that the molecular design of the polycarbonate-based copolymer corresponding to the physical properties required for various applications including the purpose of stress optical coefficient can be easily performed.

[Examples] The present invention will be described in more detail with reference to Examples.

Example 1 (1) Synthesis of styrene-based macromonomer 200 g of styrene, 2.3 g of azobisbutyronitrile (polymerization initiator) and 7.79 g of thioglycolic acid (chain transfer agent) were dissolved in 400 ml of tetrahydrofuran and heated to 60 ° C. And reacted for 3 hours. The reaction product was poured into 4 l of petroleum ether while stirring, and the polymer was precipitated, filtered, and dried. Then, the obtained polymer was dissolved in methylene chloride, washed with water, and then methylene chloride was evaporated to dryness to obtain a purified styrene macromonomer having a degree of polymerization of about 100.

(2) Synthesis of Polycarbonate Oligomer 60 kg of bisphenol A is dissolved in 400 l of a 5% caustic soda aqueous solution to prepare an aqueous solution of bisphenol A caustic soda. Then, the caustic soda aqueous solution of bisphenol A and methylene chloride kept at room temperature were respectively
At a flow rate of 138 l / hr and 69 l / hr, it was introduced into a tubular reactor with an inner diameter of 10 mm and a tube length of 10 m through an orifice plate, and phosgene was blown into it at a flow rate of 10.7 kg / hr in a cocurrent manner for 3 hours continuously It was made to react. The tubular reactor used here is a double tube, cooling water is passed through the jacket to keep the discharge temperature of the reaction solution at 25 ° C., and the pH after discharge is 10-11. The reaction solution obtained as a result is allowed to stand to separate and remove the aqueous phase, and the methylene chloride phase (220 l)
Was collected, 342 l of methylene chloride was further added thereto, and the mixture was thoroughly stirred to obtain a polycarbonate oligomer having a concentration of 220 g / l. The degree of polymerization of the oligomer obtained here is 3
It was ~ 4.

(3) Production of polycarbonate-based copolymer 153.6 g of styrene-based macromonomer obtained in (1) above
And the polycarbonate oligomer 4 obtained in (2) above
Dissolve 6.4 g in 200 ml of methylene chloride, add 2.1 ml of triethylamine, react for 1 hour with stirring, then
It was washed with hydrochloric acid and the organic phase was separated to obtain a prepolymer solution.

Add 800 ml of methylene chloride to the obtained prepolymer solution.
And Bisphenol A 12.4 g, sodium hydroxide 7.6
g and 0.08 ml of triethylamine were dissolved in water to make 170 ml.
This aqueous solution was added to the prepolymer solution, and was subjected to interfacial polycondensation while stirring, washed and separated to obtain a polycarbonate copolymer (block type).

The physical properties of the obtained polycarbonate copolymer (block type) are shown in the table.

Examples 2 and 3 In the same manner as in Example 1, polycarbonate-based copolymers (block type) having different ratios of copolymerization components were produced. The results are shown in the table.

Example 4 (1) Synthesis of styrenic macromonomer As a result of carrying out in the same manner as in Example 1 except that 20.5 g of thiomalic acid was used instead of 7.79 g of thioglycolic acid, the degree of polymerization was about 60 styrenic macromonomers were obtained.

(2) Production of Polycarbonate Graft Copolymer Styrene macromonomer 134.6 obtained in Example (1)
g, 65.4 g of the polycarbonate oligomer obtained in (2) of Example 1 and 6.0 ml of triethylamine were used.
A prepolymer solution was obtained in the same manner as in (3). Then bisphenol A 15.7 g, sodium hydroxide 9.7 g, para-tert-butylphenol 0.292 g, triethylamine.
A polycarbonate type copolymer (graft type) was obtained by the same method using 1 ml of an aqueous solution. The results are shown in the table.

The measurement of the physical property values in this example and the comparative example was performed by the following methods.

Measurement of polymer molecular weight M _W Dissolve 20 mg of sample in 80 ml of tetrahydrofuran and
It was measured by the method. (At 25 ° C) Stress optical coefficient and transparency measurement Pellets are melt-spun and the stress during melt-spinning is calculated from the tension during melt-spinning and the diameter of the yarn. The birefringence of the melt-spun spun yarn was determined by observation with a polarizing microscope under a crossed Nicols using a Berek compensator. Also, the transparency of the spinning was visually observed.

Melt spinning is a cylinder defined in JIS K 7210, using a heating furnace of 210 ° C. consisting of piston and die (melt indexer), the polymer melted at a piston extrusion speed of 10 mm / min from the melt indexer, Using a melt tension tester type II manufactured by Toyo Seiki Co., Ltd., the filament was drawn, passed through a load detector and led to a feed roll with a diameter of 50 mm, and the melt tension at a constant rate of tension was measured by the load detector.

The stress of the yarn was calculated as the melt tension per cross-sectional area of the yarn.

The birefringence of the yarn was measured by a polarizing microscope in a crossed Nicol state using a Berek compensator. The birefringence of a thread is determined by stress, independent of the thread diameter or melt tension. The birefringence value at a stress value of 1.5 MPa was read from the graph, and the slope of the straight line was taken as the stress optical coefficient and used as a parameter of optical isotropy.

Claims (1)

[Claims] 1. A component selected from (A) (a) styrene-based monomer, thiomalic acid, thioglycolic acid, 2-aminoethanethiol, 2-mercapto-1,4-butanedicarboxylic acid, and salts thereof. Polycondensation of at least one chain transfer agent, a styrene-based macromonomer obtained by the reaction with a polymerization initiator, and a prepolymer obtained by reacting (b) a polycarbonate oligomer and (B) an aromatic dioxy compound A method for producing a polycarbonate-based copolymer, comprising: