JP4575046B2 - Method for obtaining an aqueous metal salt solution of an aromatic dihydroxy compound - Google Patents

Description

  The present invention relates to an aromatic polycarbonate resin component of a laminate obtained by laminating a film formed from a resin other than an aromatic polycarbonate resin on a molded article formed from a resin mainly composed of an aromatic polycarbonate resin. The present invention relates to a method for decomposing and obtaining an aqueous solution of an aromatic dihydroxy compound metal salt and a method for recovering an aromatic dihydroxy compound from the aqueous solution. Moreover, it is related with the manufacturing method of the aromatic polycarbonate which uses the obtained aromatic dihydroxy compound metal salt aqueous solution or the collect | recovered aromatic dihydroxy compound for the manufacturing process of a polycarbonate.

  Aromatic polycarbonate (hereinafter abbreviated as PC) has excellent mechanical properties, electrical properties, heat resistance, cold resistance, transparency, etc., building materials for transparent sheets, liquid crystal television projections It is a material used in various applications such as diffusion plates / lens sheets for TVs, optical disks such as lenses, compact disks, automobile parts, chassis for OA equipment, camera bodies, and the demand for these materials is increasing year by year. Along with the increase in demand for PCs, many of the PC products to be discarded are processed by methods such as incineration or filling in the ground. This not only accelerates the depletion of petroleum resources due to the increasing demand for PC, but also promotes the deterioration of the global environment. Therefore, it has become important to reuse (recycle) discarded plastic.

  The methods for recycling waste plastics are as follows: (1) Thermal recycling in which waste plastic is recovered as thermal energy, (2) Material recycling in which waste plastic is mixed and processed in a certain proportion to the product, and (3) Waste plastic There is chemical recycling in which the material is chemically decomposed back to the raw material of the plastic and reused for plastic manufacturing. However, in thermal recycling, plastic is incinerated to extract heat, generating carbon dioxide and water, essentially destroying the global environment and reducing resources. Material recycling has the least environmental impact and is environmentally desirable in terms of resource consumption, but the products that can be mixed are limited, the proportion that can be mixed into the products is small, and the amount that can be recycled is limited. Chemical recycling is an industrially useful recycling method that can be used as it is because it decomposes plastics into raw materials.

  As a method of chemically recycling PC, a method of decomposing with an excess of alkaline aqueous solution and neutralizing to produce an aromatic dihydroxy compound has been known for a long time. For example, Patent Document 1 discloses that PC and 1-30% An alkaline aqueous solution is put in a pressure vessel, hydrolyzed at 100 ° C. or higher, preferably 150 ° C. or higher, acidified, dissolved in methanol, treated with activated carbon to remove colored components, and reprecipitated to obtain white bisphenol. Yes. Patent Document 2 discloses a method in which polycarbonate scrap is saponified with a bulk or a solution, an unsaponified component is separated, a saponified mixture is phosgenated, and used in a polycarbonate polymerization step without any purification and treatment steps. Yes. Patent Document 3 discloses a method for recovering an aromatic dihydroxy compound and a diaryl carbonate by decomposing PC with phenol in the presence of an alkali catalyst. Patent Document 4 discloses a method for obtaining a dialkyl carbonate and an aromatic dihydroxy compound by performing a transesterification reaction in a toluene, xylene, benzene or dioxane solvent using a small amount of alkali as a catalyst. Further, in Patent Document 5, PC is transesterified with a lower alcohol in the presence of a solvent such as an alkyl chloride, an ether or an aromatic hydrocarbon solvent and a tertiary amine as a catalyst to convert an aromatic dihydroxy compound and a dialkyl carbonate. The method of obtaining is proposed.

  However, since the method of Patent Document 1 uses a thin alkaline aqueous solution, the reaction becomes high temperature, and further, a large amount of water is used in the post-treatment, and the yellow coloring component is reprecipitated from methanol / water. Is very cumbersome. Since the method of Patent Document 2 is used for a polymerization reaction without a purification step, additives, colorants and the like used as almost essential components in plastics are mixed in the PC manufacturing process, which affects product quality. In the methods of Patent Documents 3 to 5, not only the decomposition and solvent separation and recovery steps are complicated, but also unnecessary by-products are generated.

Japanese Patent Publication No. 40-016536 Japanese Patent Laid-Open No. 54-048869 Japanese Patent Application Laid-Open No. 06-056885 Japanese Patent Laid-Open No. 10-259151 JP 2002-212335 A

  The purpose of the present invention is from aromatic polycarbonate molded products having a resin film other than aromatic polycarbonate, which is inexpensive, has a short decomposition time, is processed in large quantities, does not generate coloring components, and is useful for polycarbonate raw materials and the like. It is to provide an aqueous dihydroxy compound metal salt solution.

  Another object of the present invention is to provide a high-purity aromatic dihydroxy compound substantially free of aromatic polycarbonate and a resin other than aromatic polycarbonate from an aqueous solution of an aromatic dihydroxy compound metal salt obtained by decomposition of an aromatic polycarbonate component. It is to provide a way to recover.

  Still another object of the present invention is to provide a method for producing an aromatic polycarbonate using an aqueous solution of an aromatic dihydroxy compound metal salt obtained by decomposing an aromatic polycarbonate component or an aromatic dihydroxy compound recovered from the aqueous solution. It is.

  As a result of intensive investigations to solve these problems, the present inventors have determined that mild conditions can be obtained by using an appropriate amount of a solvent, preferably an aqueous metal hydroxide solution, preferably used in the production of an aromatic polycarbonate in a specific process. As a result, the aromatic polycarbonate is selectively decomposed to obtain a highly pure aqueous solution of an aromatic dihydroxy compound metal salt, and in the presence of a solvent used in the production of the aromatic polycarbonate. The aromatic dihydroxy compound metal salt aqueous solution is treated with an acid aqueous solution to obtain a higher-quality aromatic dihydroxy compound, and the aromatic dihydroxy compound metal salt aqueous solution or the obtained aromatic dihydroxy compound is used. The quality of the aromatic polycarbonate obtained by manufacturing the aromatic polycarbonate It found that not inferior quality of the aromatic polycarbonate produced using the hydroxy compound, and completed the present invention.

That is, according to the present invention,
1. Decomposes the aromatic polycarbonate resin component of the laminate in which a film formed from a resin other than the aromatic polycarbonate resin is laminated to a molded article formed from a resin containing 50% by weight or more of the aromatic polycarbonate resin with an aqueous metal hydroxide solution In the method of obtaining an aromatic dihydroxy compound metal salt aqueous solution, (1) the laminate is dissolved in at least one chlorinated compound organic solvent selected from the group consisting of dichloromethane, dichloroethane, and chloroform, and undissolved matter is filtered. The filtrate obtained in the steps (a), (2) and (1) is added to an aqueous solution of metal hydroxide which is an aqueous solution of sodium hydroxide and / or potassium hydroxide , and 100 parts by weight of the aromatic polycarbonate. contrast, sodium bisulfite 0.05 to 4.0 parts by weight of _{(Na 2 S 2 O 5)} , nitrous Sodium acid _(Na 2 _SO 3), one or antioxidants is more sodium hydrosulfite _{(Na 2} S 2 _{O 4)} was added, the step of decomposing an aromatic polycarbonate (b step), Contact and (4) A method of obtaining an aromatic dihydroxy compound metal salt aqueous solution comprising a step (step d) of separating a metal hydroxide aqueous solution phase and a chlorinated compound organic solvent phase and recovering the metal hydroxide aqueous solution phase.

2. The aromatic dihydroxy according to the preceding item 1, wherein water is added to the decomposition solution obtained in steps (3) and (2) between step b and step d to dissolve the precipitated solid component (step c). A method for obtaining an aqueous compound metal salt solution.

3. The aromatic dihydroxy compound metal salt aqueous solution according to the above item 1, wherein the resin other than the aromatic polycarbonate is at least one resin selected from the group consisting of melamine resins, acrylic resins, methacrylic resins and organopolysiloxane resins. How to get.

4. The method of obtaining the aromatic dihydroxy compound metal salt aqueous solution of the preceding clause 1 which uses 4.1-8.0 mol metal hydroxide with respect to 1 mol of carbonate bonds of an aromatic polycarbonate.

5 . The method of obtaining the aromatic dihydroxy compound metal salt aqueous solution of the preceding clause 1 whose decomposition reaction temperature in said b process is 30-80 degreeC.

6 . The method of obtaining the aromatic dihydroxy compound metal salt aqueous solution of the preceding clause 1 which uses 40-2000 weight part chlorinated compound organic solvent with respect to 100 weight part of aromatic polycarbonate.

7). Manufacture of the aromatic polycarbonate which obtains aromatic dihydroxy compound metal salt aqueous solution from a laminated body by the method of any one of the preceding clauses 1-6, and reuses the obtained aromatic dihydroxy compound metal salt aqueous solution for a polycarbonate manufacturing process. Method.

8). The aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method described in any one of 1 to 6 above, and the obtained aromatic dihydroxy compound metal salt aqueous solution is contacted with a chlorinated compound organic solvent comprising methylene chloride. And then separating the organic solvent phase and the aqueous solution phase, and using the aqueous solution in the polycarbonate production process.

9. The aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method described in any one of the preceding items 1 to 6, and the resulting aqueous solution of the aromatic dihydroxy compound metal salt is an aqueous solution of hydrochloric acid, sulfuric acid or phosphoric acid. A method for recovering an aromatic dihydroxy compound by precipitating an aromatic dihydroxy compound and filtering.

10. The aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method described in any one of the preceding items 1 to 6, and the resulting aromatic dihydroxy compound metal salt aqueous solution is mixed with a chlorinated compound organic solvent composed of methylene chloride and hydrochloric acid, A method of recovering an aromatic dihydroxy compound by adding an acid aqueous solution that is an aqueous solution of sulfuric acid or phosphoric acid, precipitating an aromatic dihydroxy compound, and filtering.

11. The aromatic dihydroxy compound is recovered by the method described in the preceding item 9 or 10 , and the recovered aromatic dihydroxy compound is further mixed with a chlorinated compound organic solvent and / or pure water comprising methylene chloride, and then the aromatic dihydroxy compound is filtered. A method of separating compounds and recovering an aromatic dihydroxy compound.

12 The manufacturing method of the aromatic polycarbonate which collect | recovers an aromatic dihydroxy compound by the method of any one of the preceding clauses 9-11, and uses the collect | recovered aromatic dihydroxy compound for a polycarbonate manufacturing process.
Is provided.

Hereinafter, the present invention will be described in detail.
(About laminates)
In the present invention, the laminate used is a laminate in which a film formed from a resin other than the aromatic polycarbonate resin is laminated on a molded article formed from a resin containing 50% by weight or more of an aromatic polycarbonate resin.

  The shape of the molded product formed from the resin containing 50% by weight or more of the aromatic polycarbonate resin is not particularly limited, and for example, a sheet-shaped molded product is used. The molded article is formed of a resin containing 50% by weight or more of an aromatic polycarbonate resin, preferably 60% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more. Particularly preferred are molded articles formed substantially from aromatic polycarbonate resins. For the above molded products, heat stabilizers, antioxidants, mold release agents (fatty acid esters, etc.), lubricants, plasticizers, antistatic agents, whitening agents, UV absorbers, Modification improvers such as antibacterial agents, pigments, dyes, fillers, reinforcing agents, diffusing agents, flame retardants, and the like can be added as appropriate.

  In addition, a film made of a resin other than the aromatic polycarbonate resin is laminated on the molded product. As the resin other than the aromatic polycarbonate resin, at least one resin selected from the group consisting of melamine resins, acrylic resins, methacrylic resins, and organopolysiloxane resins is preferable. Films formed from these resins have effects such as preventing scratches and improving weather resistance. For the purpose of imparting functionality, a modification / improving agent such as an ultraviolet absorber, an antistatic agent, or a fluorescent brightening agent can be appropriately added to the film.

The method of laminating the film on the molded product is not particularly limited. For example, a laminating method in which a resin composition that forms a film on the molded product is melt-extruded and fused, or a film previously formed into a film shape is molded. A laminating method in which a heated roll or the like is continuously pressed onto the surface of a molded product in the course of the manufacturing process, a co-extrusion method in which a molded product and a resin composition that forms a film are melt-extruded simultaneously, and a resin that forms a film Examples thereof include a method in which a coating material containing the composition is applied to the surface of a molded article by a coating method such as a dip coating method, a flow coating method, or a roll coating method.
The thickness of the film is preferably in the range of 0.1 to 1000 μm, more preferably in the range of 1 to 500 μm.

  Specific examples of the laminate include a polycarbonate resin light diffusing plate coated with a film having an ultraviolet absorbing ability used for liquid crystal displays and liquid crystal televisions, a polycarbonate resin window glass having a surface coated with a protective film, and ultraviolet light. Glasses made of polycarbonate resin coated with a protective film with absorbability and scratch resistance, headlamp lenses made of polycarbonate resin for automobiles coated with a protective film with scratch resistance, coated with a protective film with scratch resistance For example, a windshield made of polycarbonate resin for motorcycles. Moreover, as a laminated body used by this invention, the defective article etc. which generate | occur | produced in the middle of manufacture can be used.

The polycarbonate in the present invention may be produced by a known method such as an interfacial polymerization method or a melt polymerization method, and the molecular weight is preferably a viscosity average molecular weight of 1000 to 100,000. Here, the viscosity average molecular weight (M) of the polycarbonate resin is obtained by inserting the specific viscosity (η _sp ) obtained from a solution obtained by dissolving 0.7 g of the polycarbonate resin in 100 ml of methylene chloride at 20 ° C. into the following equation. .
η _sp /c=[η]+0.45×[η] ² c (where [η] is the intrinsic viscosity)
[Η] = 1.23 × 10 ⁻⁴ M ^0.83
c = 0.7

  The polycarbonate includes hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, 1,4-dihydroxynaphthalene, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, , 1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), 2,2 -Bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(3,5-dibromo- 4-hydroxy) phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propa 2,2-bis {(4-hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, , 2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2 -Bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis ( 4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- {(4-hydroxy-3-methyl) phenyl} fluorene, α, α'-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene , Α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4'-dihydroxydiphenylsulfone, 4,4 One or more dihydroxy compounds such as' -dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxydiphenyl ester Made from a mixture of

  Moreover, as a terminal stopper (molecular weight regulator), a monovalent phenol compound is preferably used, and phenol, p-cresol, p-ethylphenol, p-isopropylphenol, p-tert-butylphenol, p-cumylphenol. , P-cyclohexylphenol, p-octylphenol, p-nonylphenol, 2,4-xylenol, p-methoxyphenol, p-hexyloxyphenol, p-decyloxyphenol, o-chlorophenol, m-chlorophenol, p-chloro Phenol, p-bromophenol, pentabromophenol, pentachlorophenol, p-phenylphenol, p-isopropenylphenol, 2,4-di (1′-methyl-1′-phenylethyl) phenol, β-naphthol, α -NA Phthol, phenols such as p- (2 ′, 4 ′, 4′-trimethylchromanyl) phenol, 2- (4′-methoxyphenyl) -2- (4 ″ -hydroxyphenyl) propane, etc. alone or 2 A mixture of seeds or more is used.

(About step a)
In the present invention, a chlorinated compound organic solvent is required. Without the chlorinated organic solvent, the surface area of the polycarbonate resin layer in the laminate is small, the decomposition reaction becomes very slow, and an excessively high temperature is required. And the purity of the resulting aromatic dihydroxy compound may be reduced.

  In the step of dissolving the laminate in a chlorinated compound organic solvent and filtering the undissolved material (step a), the amount of the chlorinated compound organic solvent used is in the range of 40 to 2000 parts by weight with respect to 100 parts by weight of the polycarbonate resin. Is preferable, 200 to 1000 parts by weight is more preferable, and 450 to 700 parts by weight is particularly preferable. When the amount of the solvent is less than 40 parts by weight, the initial mixing is insufficient, the polycarbonate resin is not sufficiently dissolved, and the time until the decomposition reaction ends may be long. On the other hand, when the amount is more than 2000 parts by weight, the carbonate bond concentration and the catalyst concentration in the reaction system become low, the decomposition reaction rate decreases, the decomposition reaction time becomes long, and the solvent recovery cost may increase.

  The chlorinated compound organic solvent used in the present invention is preferably at least one solvent selected from the group consisting of dichloromethane, dichloroethane and chloroform, with dichloromethane being particularly preferred. These solvents are good solvents for polycarbonate, and are actually used as reaction solvents in the polycarbonate production process. Even if the solvent remains in the aromatic dihydroxy compound after decomposition and separation, the production of polycarbonate is adversely affected. It is because it does not reach.

  When the laminate is dissolved in the chlorinated compound organic solvent, there are undissolved substances in the polycarbonate resin solution, for example, an additive contained in the molded article and a laminated film (melamine resin or organopolysiloxane resin). These undissolved substances must be removed by filtration. When the polycarbonate resin decomposition reaction is performed without removing the undissolved substances, these undissolved substances may also be decomposed and mixed into the aromatic dihydroxy compound metal salt aqueous solution after the decomposition reaction, resulting in decomposition products that become impurities. When an aqueous solution for the polycarbonate production process is used with the mixture being mixed, it adversely affects the quality of the obtained polycarbonate resin, so it is necessary to remove it in advance. The chlorinated compound organic solvent solution (filtrate) in which the filtered polycarbonate resin is dissolved is used in the next step.

(About step b)
A metal hydroxide aqueous solution is added to the chlorinated compound organic solvent solution (filtrate) in which the polycarbonate resin obtained in step a is dissolved to decompose the aromatic polycarbonate (step b).
Metal hydroxide is used in the decomposition reaction of the aromatic polycarbonate. Examples of the metal hydroxide include sodium hydroxide and potassium hydroxide. Sodium hydroxide is particularly preferable.

  The amount of metal hydroxide used is preferably 4.1 to 8.0 moles per mole of carbonate bond in the polycarbonate resin. When the amount used is less than 4.1 mol, the decomposition reaction becomes very slow, and when it exceeds 8.0 mol, the cost increases, and the amount of the aqueous acid solution used for isolating and recovering the aromatic dihydroxy compound This is economically undesirable.

  The metal hydroxide is used in the form of an aqueous solution. The concentration of the metal hydroxide is preferably 30% by weight to 55% by weight. When it is lower than 30% by weight, the decomposition rate is slow, and when it exceeds 55% by weight, metal hydroxide is easily precipitated and becomes a slurry, and when it becomes a slurry, the reaction is rather slow.

  In this invention, 30 to 80 degreeC is preferable and the temperature which performs a decomposition reaction has more preferable 30 to 50 degreeC. When it is less than 30 ° C., the decomposition reaction time becomes long, and the processing efficiency may be remarkably inferior. In addition, when the temperature exceeds 80 ° C., resin components other than polycarbonate (especially acrylic resins and methacrylic resins that dissolve in chlorinated organic solvents and exist in the filtrate) may cause a decomposition reaction. Or methacrylic monomers may be mixed in the aqueous solution of the aromatic dihydroxy compound metal salt after the decomposition reaction and become impurities, thereby reducing the purity of the aromatic dihydroxy compound. In addition, a large amount of heating energy is required, and the color of the solution is likely to turn brown during the decomposition treatment, so that a high-quality aromatic dihydroxy compound aqueous solution may not be obtained.

  Since the aromatic dihydroxy compound produced during the decomposition reaction is easily oxidized under basic conditions, it is preferable to add an antioxidant to the reaction solution. It is also effective to reduce the oxygen concentration in the process with an inert gas.

Examples of the antioxidant include sodium bisulfite (Na ₂ S ₂ O ₅ ), sodium sulfite (Na ₂ SO ₃ ), and sodium hydrosulfite (Na ₂ S ₂ O ₄ ). These may be used alone or in combination of two or more. As for the usage-amount of antioxidant, 0.05-4.0 weight part is preferable with respect to 100 weight part of aromatic polycarbonate. If it is in the range of 0.05 to 4.0 parts by weight, it has an antioxidant effect, is advantageous in terms of cost, and is preferable because the decomposition reaction rate does not decrease.
Nitrogen, argon etc. are mentioned as a kind of inert gas. Nitrogen is preferred because of its cost advantage.

  The method for decomposing the aromatic polycarbonate resin in the present invention is an interfacial reaction, and the aromatic polycarbonate resin dissolved or swollen in the organic solvent of the chlorinated compound is stirred with the aqueous metal hydroxide solution and decomposed upon contact with the interface. Is done. This reaction is irreversible, and the carbonate bond of the aromatic polycarbonate resin is broken and decomposes into an aromatic dihydroxy compound metal salt and a carbonate metal salt.

(About step c)
When the aromatic dihydroxy compound metal salt and carbonate metal salt produced in the hydroxide aqueous solution obtained after the decomposition reaction obtained in step b above are not dissolved and are precipitated as a solid component, they are precipitated by adding water. A step of dissolving the solid part (step c) is performed, and then the step d is performed. On the other hand, when the aromatic dihydroxy compound metal salt and the metal carbonate formed after the decomposition reaction are dissolved in the metal hydroxide aqueous solution, the process proceeds directly to step d described later.

  In step c, water is added to the reaction solution after the decomposition reaction and stirred, and the precipitated aromatic dihydroxy compound metal salt and carbonate metal salt are dissolved. The amount of water to be added is more than the amount that completely dissolves the solid component, but if too much is added, the concentration of the aromatic dihydroxy compound metal salt in the aqueous solution will decrease and it will be used in the production process of aromatic polycarbonate. In addition, since the reaction rate is reduced and the waste liquid distillation cost is increased, the minimum amount that completely dissolves the solid is preferable. When water is added to the decomposition solution to dissolve the solid component, it is separated into two phases, an organic solvent phase and an aqueous phase of an aromatic dihydroxy compound metal salt.

(About step d)
Next, the metal hydroxide aqueous solution phase and the chlorinated compound organic solvent phase are separated to recover the metal hydroxide aqueous solution phase (step d).

  The metal hydroxide aqueous solution phase and the chlorinated compound organic solvent phase are separated by a liquid-liquid separator such as a decanter to recover the metal hydroxide aqueous solution phase (aqueous phase). The recovered aqueous solution of the aromatic dihydroxy compound metal salt can be used as it is in the production process of the aromatic polycarbonate. If separation is insufficient in the liquid-liquid separator, a heavy liquid phase floating in a granular form is mixed in the aqueous phase, and when this aqueous phase is used in the production process of the polycarbonate resin, the quality of the obtained polycarbonate resin is improved. It is preferred that the aqueous phase be further contacted with a chlorinated compound organic solvent and removed as much as possible. As this method, a known method such as contact with a washing tower, separation with a stirrer, liquid-liquid separator, or centrifugal separator can be used.

  An aqueous solution of an aromatic dihydroxy compound metal salt obtained by decomposing an aromatic polycarbonate and an aqueous solution prepared by mixing a purchased aromatic dihydroxy compound may be mixed at an arbitrary ratio and used in the process for producing an aromatic polycarbonate. it can.

  Moreover, an acid can be added to the aqueous solution of the aromatic dihydroxy compound metal salt obtained by decomposing | disassembling an aromatic polycarbonate, an aromatic dihydroxy compound can be precipitated, and an aromatic dihydroxy compound can also be isolated and collect | recovered. By solidifying, an aromatic dihydroxy compound raw material having a higher purity can be obtained than the method of using the solution in the production process of the aromatic polycarbonate.

A preferred method for precipitating the aromatic dihydroxy compound is to add the acid aqueous solution to a granulation tank in which the aqueous solution of the aromatic dihydroxy compound metal salt is stirred and / or circulated in the presence or absence of the chlorinated compound organic solvent. It is a method of adding. According to this method, an aromatic dihydroxy compound that does not dissolve in an aqueous phase and an organic solvent phase is obtained as a slurry, and an aromatic dihydroxy compound can be obtained by filtering the slurry. The final pH of the aqueous phase is preferably in the range of 4-10. More preferably, it is the range of pH 6-8.5.
Although the kind of acid of the acid aqueous solution to be used is not particularly limited, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid are preferably used.
Examples of the method for filtering the aromatic dihydroxy compound obtained as a solid include a filter, a centrifuge, and a centrifugal sedimentation device. A centrifuge is preferable because the liquid content after filtration is low.

  The aromatic dihydroxy compound obtained by the above method is unpurified and added with impurities other than the aromatic dihydroxy compound present in the aqueous phase and the organic solvent phase, for example, a terminal terminator, a coloring agent for molded articles, etc. Agents, carbonates derived from polycarbonate, neutral salts produced by the reaction of metal hydroxides and aqueous acid solutions, and the like. These impurities can be removed by contacting and washing with pure water and a chlorinated compound organic solvent, and the purity of the aromatic dihydroxy compound is improved.

  As a washing method, a solid aromatic dihydroxy compound is transferred to a stirring tank, and water or a chlorinated compound organic solvent is added simultaneously or separately, followed by stirring and filtration. Water, chlorinated compound organic in a centrifuge Examples include a method in which the solvent is sprinkled simultaneously or separately and the solution is removed by centrifugation as it is.

  The solid aromatic dihydroxy compound recovered by the method of the present invention can be reused in the production process of the aromatic polycarbonate. As a re-use method, it can be used as it is in the melt polymerization method, and in the interfacial polymerization method, it can be dissolved in a metal hydroxide aqueous solution at a desired concentration and used for the production of an aromatic polycarbonate. . At that time, it is also preferable to use a solution obtained by heating a solution obtained by dissolving an aromatic dihydroxy compound in a metal hydroxide aqueous solution and volatilizing the remaining chlorinated compound organic solvent.

  Moreover, you may use together the collect | recovered aromatic dihydroxy compound and a commercially available aromatic dihydroxy compound for manufacture of an aromatic polycarbonate. The method for mixing the recovered aromatic dihydroxy compound and the commercially available aromatic dihydroxy compound may be any method of solids, solids and liquids, or liquids.

  The polycarbonate resin obtained by the production method of the present invention includes a heat stabilizer, an antioxidant, a release agent (fatty acid ester, etc.), a lubricant, a plasticizer, an antistatic agent, a whitening agent, an ultraviolet absorber, a weathering agent, Antibacterial agents, pigments, dyes, fillers, reinforcing agents, polymers such as other resins and rubbers, and modifiers such as flame retardants can be appropriately added and used.

  As the heat stabilizer, a phosphorus heat stabilizer is preferably used, and examples thereof include phosphorous acid, phosphoric acid, phosphonous acid, phosphonic acid and esters thereof. Specifically, tris (nonylphenyl) Phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris (2,6-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, trimethyl phosphate, 4,4 ′ -Biphenylene diphosphinic acid tetrakis (2,4-di-tert-butylphenyl) and the like are preferably used. These can be used individually or in mixture of 2 or more types. The blending amount of these heat stabilizers is preferably 0.001 to 0.1 parts by weight, more preferably 0.002 to 0.05 parts by weight with respect to 100 parts by weight of the polycarbonate resin.

  The heat stabilizer may be added to the polycarbonate resin by any method of adding to the polycarbonate resin solution after the polymerization reaction and adding to the polycarbonate resin powder. In particular, the method of adding to the polycarbonate resin solution after the polymerization reaction preferably improves the hue and thermal stability of the polycarbonate resin, and the method of adding to the polycarbonate resin solution after completion of purification or warm water when granulating with warm water The method of adding in is preferable. The heat stabilizer may be dissolved in a solvent or added as it is.

  In addition, the polycarbonate resin obtained by the production method of the present invention is excellent in hue and thermal stability, so that, for example, a magneto-optical disk, various write-once disks, a digital audio disk (so-called compact disk), an optical video disk (so-called laser). Disk), a material for an optical disk substrate such as a digital versatile disk (DVD), and a material for a precision equipment storage container such as a silicon wafer. Moreover, it can recycle | recycle and use as polycarbonate resin molded products, such as a light diffusing plate, a window glass, a spectacle lens, a headlamp lens for motor vehicles, and a windshield for motorcycles.

  According to the present invention, a polycarbonate component of a laminate in which a film formed from a resin other than an aromatic polycarbonate is laminated on a molded product made of an aromatic polycarbonate, the decomposition time is short, and the resin component other than the aromatic polycarbonate is also decomposed. A high-purity aromatic dihydroxy compound can be obtained without contamination, and the obtained aromatic dihydroxy compound or an aqueous metal hydroxide solution thereof can be used as a raw material for producing an aromatic polycarbonate. Is exceptional.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Unless indicated otherwise, parts represent parts by weight. The evaluation was performed by the following method.

(1) Hue (b value)
Using a polycarbonate resin pellet, a 50 mm square plate having a thickness of 2 mm was molded at a cylinder temperature of 340 ° C. using an injection molding machine (manufactured by Nippon Steel Works, Ltd .: Nikko Anchor V-17-65 type). The molded plate was measured for b value using a color difference meter (manufactured by Nippon Denshoku Co., Ltd.).

(2) Thermal stability (△ E)
Test pieces (thickness 2 mm) of polycarbonate resin pellets that were not allowed to stay for 10 minutes at a cylinder temperature of 340 ° C. using an injection molding machine (manufactured by Nippon Steel Co., Ltd .: Nikko Anchor V-17-65 type) 50 mm square plate) was prepared, and the change in hue (ΔE) was measured. The change in hue was calculated by measuring the L, a and b values with a color difference meter (manufactured by Nippon Denshoku Co., Ltd.) and using the following equation.
ΔE = [(L′−L) ² + (a′−a) ² + (b′−b) ² ] ^1/2
(L, a, b are not retained, L ′, a ′, b ′ are retained for 10 minutes)

(3) Bisphenol A concentration in bisphenol A aqueous solution The bisphenol A aqueous solution was diluted with sodium hydroxide aqueous solution so as to be 0.1 to 0.5% by weight, and the absorbance was measured with a UV meter at a wavelength of 294 nm. The bisphenol A concentration in the aqueous solution was measured by a wire.

(4) Purity of bisphenol A (bisphenol A purity in organic matter)
Using Waters high performance liquid chromatography, 0.2 mL of sample (organic matter) was dissolved by adding 1 mL of acetonitrile with o-cresol added as an internal standard, and a chromatograph was obtained using acetonitrile / 0.2% acetic acid aqueous solution as a developing solvent. The purity of bisphenol A was determined using a calibration curve prepared in advance.

(5) Sodium ion content of bisphenol A 10 mL of ultrapure water was added to 1 g of bisphenol A and allowed to stand for 24 hours to extract ionic components. An ion chromatograph was obtained from this solution, and the amount of sodium ions was determined using a calibration curve prepared in advance.

[Example 1]
100 parts of a commercially available polycarbonate resin light diffusing plate (a 2 mm thick polycarbonate resin sheet containing a silicon light diffusing agent having an average particle diameter of 2 μm and a 40 μm thick acrylic laminate) in a stirring tank and chloride 600 parts of methylene was added and stirred for 6 hours. The silicon light diffusing agent was dispersed in a methylene chloride solution of polycarbonate. This solution was passed through a filter (manufactured by Advantech) equipped with a metal filter having an opening of 1 μm to remove the diffusing agent.

  Into a reactor equipped with a thermometer, stirrer, reflux condenser and water bath, 264 parts of methylene chloride solution of the polycarbonate (dope concentration 14.2%), 71 parts of 50% aqueous sodium hydroxide solution (based on 1 mol of carbonate bond of polycarbonate 6.0 mol) and 0.6 part of hydrosulfite sodium was added and stirred. Thereafter, when the water bath temperature was adjusted to 40 ° C., the reflux began vigorously after 8 minutes, and the intensity was reduced after 20 minutes. After 5 hours of reaction, a solid was precipitated inside, and a part of the solid was collected and analyzed, and it was bisphenol A sodium salt and sodium carbonate. The temperature adjustment of the water bath was stopped, 337.5 parts of pure water was added, and stirring was continued for 1 hour to dissolve the solid.

  The reaction mixture was transferred to a separatory funnel and separated into 455 parts aqueous phase and 224 parts organic phase. The aqueous phase was an alkaline aqueous solution and contained bisphenol A, sodium carbonate, sodium hydroxide, p-tertiary butylphenol sodium salt, and it was confirmed that no acrylic monomer or acrylic polymer was detected by NMR. The organic phase was evaporated and recovered with an evaporator, and the residue was discarded. The residue was a decomposition product of unreacted polycarbonate, acrylic polymer and additives, and its weight was 1.1 parts.

  100 parts of methylene chloride was added to 455 parts of the separated aqueous phase, mixed vigorously and allowed to stand to separate the aqueous phase and the methylene chloride phase. Methylene chloride was recovered with an evaporator. This operation was repeated three times to obtain a washed bisphenol A aqueous solution (bisphenol A concentration: 76.6 g / L).

[Example 2]
In Example 1, the same operation as in Example 1 was carried out except that the amount of methylene chloride mixed with 100 parts of the polycarbonate resin light diffuser plate and 360 parts of the methylene chloride solution of polycarbonate were used. (Bisphenol A concentration 74.7 g / L) was obtained.

[Example 3]
In Example 1, the same operation as in Example 1 was carried out except that 56.3 parts of a 50% aqueous sodium hydroxide solution (4.8 moles per 1 mole of carbonate bond of polycarbonate) was used. A concentration 75.0 g / L) was obtained.

[Example 4]
455 parts of the bisphenol A aqueous solution obtained in Example 1 was transferred to a thermometer, a stirrer and a container equipped with a reflux condenser, and 170 parts of methylene chloride was newly added and stirred. While stirring, 36.1 parts of 98% concentrated sulfuric acid was added dropwise over 1 hour using a dropping funnel. When stirring was stopped and the inside was confirmed, the inside of the container was divided into three phases: an aqueous phase, a methylene chloride phase, and precipitated bisphenol A.

  The slurry was filtered with a centrifuge and sprinkled on the solid in the order of 45 parts of methylene chloride, 45 parts of pure water, 45 parts of methylene chloride, and 45 parts of pure water while operating in the centrifuge to perform rinse washing. The solid was scraped out of the centrifuge and the weight after drying was measured to be 26.9 parts. The purity of bisphenol A was 99.8% and the sodium ion content was 8 ppm.

[Example 5]
In Example 4, after filtration with a centrifuge, the solid was scraped out without rinsing, and the weight after drying was measured to be 29.9 parts. The purity of bisphenol A was 98.2% and the sodium ion content was 1.3%.

[Example 6]
In Example 4, the same operation was performed except that 170 parts of methylene chloride was not added. However, the internal state after the dropwise addition of concentrated sulfuric acid was an aqueous slurry containing no methylene chloride.
The slurry was filtered with a centrifuge and sprinkled on the solid in the order of 45 parts of methylene chloride, 45 parts of pure water, 45 parts of methylene chloride, and 45 parts of pure water while operating in the centrifuge to perform rinse washing. The solid was scraped from the centrifuge, and the weight after drying was measured to find 27.4 parts. The purity of bisphenol A was 99.5% and the sodium ion content was 15 ppm.

[Reference Example 1] (Production of polycarbonate resin)
(A) A thermometer, a stirrer, a reflux condenser, and a reactor equipped with a circulator were charged with 650 parts of ion-exchanged water and 252 parts of a 25% aqueous sodium hydroxide solution, and 170 parts of purchased bisphenol A, 13 parts of methylene chloride and 0.34 part of hydrosulfite was added, the temperature was maintained at 30 ° C. while circulating, and dissolved in 40 minutes to prepare a bisphenol A aqueous solution.

  (B) A thermometer, a stirrer, and a reactor equipped with a reflux condenser were charged with 367 parts of the bisphenol A aqueous solution prepared in (A), 181 parts of methylene chloride was added, and 28.3 parts of phosgene at 15 to 25 ° C. with stirring. It took 40 minutes to blow. After completion of the phosgene blowing, 7.2 parts of a 48% aqueous sodium hydroxide solution and 1.55 parts of solid p-tertiary butylphenol were added and emulsified. After 10 minutes, 0.06 part of triethylamine was added, and further 28 to 33 The reaction was terminated by stirring for 1 hour at ° C. After completion of the reaction, 400 parts of methylene chloride was added to and mixed with the product, the stirring was stopped, and the aqueous phase and the organic phase were separated to obtain an organic solvent solution having a polycarbonate resin concentration of 14.5% by weight.

  After adding 150 parts of water to this organic solvent solution and stirring and mixing, stirring was stopped and the aqueous phase and the organic phase were separated. To this organic phase, 200 parts of aqueous hydrochloric acid having a pH of 3 was added and mixed by stirring to extract triethylamine and the like. Then, stirring was stopped and the aqueous phase and the organic phase were separated. Next, 200 parts of ion-exchanged water was added to the separated organic phase, and the mixture was stirred and mixed. Then, the stirring was stopped and the aqueous phase and the organic phase were separated. This operation was repeated (four times) until the conductivity of the aqueous phase was almost the same as that of ion-exchanged water. The obtained purified polycarbonate resin solution was filtered with a 1 μm filter made of SUS304.

  Next, 100 L of ion-exchanged water is poured into a 1000 L kneader made of SUS316L with an inner wall provided with an isolation chamber having a foreign matter outlet at the bearing portion, and methylene chloride is evaporated at a water temperature of 42 ° C. The powder and the mixture of the powder and water were put into a hot water treatment tank of a hot water treatment process having a hot water treatment tank with a stirrer controlled at a water temperature of 95 ° C. The mixture was stirred for 30 minutes at a mixing ratio of 75 parts of water. This mixture of powder and water was separated with a centrifuge to obtain a powder containing 0.5% by weight of methylene chloride and 45% by weight of water. Next, this granular material is continuously supplied at 50 kg / h (in terms of polycarbonate resin) to a SUS316L conductive heat receiving groove type biaxial stirring continuous dryer controlled at 140 ° C., and the condition of an average drying time of 3 hours. And dried to obtain a granular material.

  Tris (2,6-di-tert-butylphenyl) phosphite was 0.010% by weight and tetrakis (2,4-di-tert-butylphenyl) 4,4′-biphenylenediphosphinic acid (0,4) were added to the powder. 0.010% by weight and 0.080% by weight of stearic acid monoglyceride were added and mixed. Next, this powder and granule are melt kneaded and extruded by a vent type twin screw extruder [TEM-50B manufactured by TOSHIBA MACHINE CO., LTD.] With a cylinder temperature of 280 ° C. and a suction vacuum of 700 Pa using a dry vacuum pump. A pellet was obtained. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

[Example 7]
In Reference Example 1 (B), instead of 367 parts of the aqueous solution prepared in Reference Example 1 (A), 9.5 parts of the aqueous solution obtained in Example 1 and 362.6 of the aqueous solution prepared in Reference Example 1 (A) were used. The pellets were obtained in the same manner as in Reference Example 1 except that the components were used. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

[Example 8]
In Reference Example 1 (A), instead of the purchased bisphenol A, the same procedure as in Reference Example 1 was performed except that the recovered bisphenol A obtained in Example 4 was used to prepare a pellet. Got. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

[Example 9]
In Reference Example 1 (A), instead of the purchased bisphenol A, the same procedure as in Reference Example 1 was carried out except that the recovered bisphenol A obtained in Example 5 was used to prepare a pellet. Got. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

[Example 10]
In Reference Example 1 (A), instead of the purchased bisphenol A, the same procedure as in Reference Example 1 was performed except that the recovered bisphenol A obtained in Example 6 was used to prepare a pellet. Got. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

[Example 11]
In Reference Example 1 (A), in place of the purchased bisphenol A, a bisphenol A aqueous solution was prepared using a mixture of the recovered bisphenol A obtained in Example 4 and the purchased bisphenol A in a ratio of 5:95. Performed the same operation as in Reference Example 1 to obtain pellets. The obtained pellets were molded and evaluated for hue and thermal stability. The results are shown in Table 1.

Claims (12)

Decomposes the aromatic polycarbonate resin component of the laminate in which a film formed from a resin other than the aromatic polycarbonate resin is laminated to a molded article formed from a resin containing 50% by weight or more of the aromatic polycarbonate resin with an aqueous metal hydroxide solution In the method of obtaining an aromatic dihydroxy compound metal salt aqueous solution, (1) the laminate is dissolved in at least one chlorinated compound organic solvent selected from the group consisting of dichloromethane, dichloroethane, and chloroform, and undissolved matter is filtered. The filtrate obtained in the steps (a), (2) and (1) is added to an aqueous solution of metal hydroxide which is an aqueous solution of sodium hydroxide and / or potassium hydroxide, and 100 parts by weight of the aromatic polycarbonate. contrast, sodium bisulfite 0.05 to 4.0 parts by weight of _{(Na 2 S 2 O 5)} , nitrous Sodium acid _(Na 2 _SO 3), one or antioxidants is more sodium hydrosulfite _{(Na 2} S 2 _{O 4)} was added, the step of decomposing an aromatic polycarbonate (b step), and ( 4) A method for obtaining an aromatic dihydroxy compound metal salt aqueous solution comprising a step (step d) of separating a metal hydroxide aqueous solution phase and a chlorinated compound organic solvent phase and recovering the metal hydroxide aqueous solution phase.   The aromatic according to claim 1, wherein a step (c step) is carried out between step b and step d by adding water to the decomposition solution obtained in steps (3) and (2) to dissolve the precipitated solid component. A method of obtaining a dihydroxy compound metal salt aqueous solution.   The aromatic dihydroxy compound metal salt aqueous solution according to claim 1, wherein the resin other than the aromatic polycarbonate is at least one resin selected from the group consisting of a melamine resin, an acrylic resin, a methacrylic resin, and an organopolysiloxane resin. How to get.   The method of obtaining the aromatic dihydroxy compound metal salt aqueous solution of Claim 1 using 4.1-8.0 mol metal hydroxide with respect to 1 mol of carbonate bonds of an aromatic polycarbonate.   The method for obtaining an aqueous solution of an aromatic dihydroxy compound metal salt according to claim 1, wherein the temperature of the decomposition reaction in the step b is 30 to 80 ° C.   The method of obtaining the aromatic dihydroxy compound metal salt aqueous solution of Claim 1 using 40-2000 weight part chlorinated compound organic solvent with respect to 100 weight part of aromatic polycarbonate. Production of an aromatic dihydroxy compound metal salt aqueous solution from a laminate by the method according to any one of claims 1 to 6, and production of an aromatic polycarbonate using the obtained aromatic dihydroxy compound metal salt aqueous solution in a polycarbonate production process Method. An aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method according to claim 1 , and the obtained aromatic dihydroxy compound metal salt aqueous solution is contacted with a chlorinated compound organic solvent comprising methylene chloride. Then, it is separated into an organic solvent phase and an aqueous solution phase, and the aqueous solution is used in the polycarbonate production process. An aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method according to any one of claims 1 to 6, and the resulting aromatic dihydroxy compound metal salt aqueous solution is an acid that is an aqueous solution of hydrochloric acid, sulfuric acid, or phosphoric acid. A method of recovering an aromatic dihydroxy compound by adding an aqueous solution, precipitating an aromatic dihydroxy compound, and filtering. An aromatic dihydroxy compound metal salt aqueous solution is obtained from the laminate by the method according to any one of claims 1 to 6, and the resulting aromatic dihydroxy compound metal salt aqueous solution contains a chlorinated compound organic solvent and hydrochloric acid comprising methylene chloride. A method of recovering an aromatic dihydroxy compound by adding an acid aqueous solution which is an aqueous solution of sulfuric acid or phosphoric acid to precipitate an aromatic dihydroxy compound and filtering. The aromatic dihydroxy compound is recovered by the method according to claim 9 or 10 , and the recovered aromatic dihydroxy compound is further mixed with a chlorinated compound organic solvent and / or pure water comprising methylene chloride, and then the aromatic dihydroxy compound is filtered. A method for separating an aromatic dihydroxy compound and recovering an aromatic dihydroxy compound. The manufacturing method of an aromatic polycarbonate which collect | recovers an aromatic dihydroxy compound by the method of any one of Claims 9-11, and uses the collect | recovered aromatic dihydroxy compound for a polycarbonate manufacturing process.