JP6803302B2 - Manufacturing method of polycarbonate resin molded product and polycarbonate resin molded product - Google Patents

Description

The present invention relates to a method for producing a polycarbonate resin pellet, an extrusion-molded product, and an injection-molded product with less coloring and a good hue, and a polycarbonate resin pellet, an extrusion-molded product, and an injection-molded product.

Polycarbonate resin has many excellent properties such as excellent transparency, heat resistance, mechanical properties, and high dimensional accuracy, and is widely used in a wide range of fields. For example, molded products are manufactured by extrusion molding of polycarbonate resin pellets or the like, injection molding, or the like. Polycarbonate resin having excellent transparency and the like is also widely used in optical applications such as optical lenses and films. However, as the size of molded products made of polycarbonate resin (hereinafter, simply referred to as "molded products") increases and the number of applications in which light is incident parallel to a flat surface such as a light guide plate increases, higher transparency is required. As a result, the problem of transparency, which has not been a problem in the past, has become apparent. That is, it is conspicuous that the molded product is colored yellow (amber), and it is difficult to use it as it is in a field where high transparency is required.

In order to solve such a problem, for example, JP-A-06-145337 specifies pretreatment at the time of synthesizing a polycarbonate resin, and JP-A-05-331277 and JP-A-2002-533544. The publication discloses a technique for controlling the oxygen concentration during synthesis. Further, Japanese Patent Application Laid-Open No. 06-145492 discloses a technique for blending an antioxidant with a polycarbonate copolymer. Further, in a method for producing an extruded resin processed product, Japanese Patent Application Laid-Open No. 2009-029031 discloses a technique for deoxidizing a resin raw material by general vacuum drying before extrusion molding. Further, Japanese Patent Application Laid-Open No. 2001-08817 discloses a technique for flowing an inert gas into a hopper provided in a molding apparatus.

However, even if pretreatment is applied during the synthesis of the polycarbonate resin, the oxygen concentration during the synthesis is controlled, or even if an antioxidant is added to the polycarbonate resin, the polycarbonate resin is synthesized and manufactured after the polycarbonate resin is synthesized. If the polycarbonate resin is left exposed to the atmosphere, the amount of dissolved oxygen gas in the polycarbonate resin will increase before it is actually used for molding, and the optimum amount of the antioxidant will change. That is, even if a sufficient amount of antioxidant is added immediately after production, the amount will be insufficient after being left in the air after production, and the polycarbonate resin will be colored. On the other hand, if the amount added is sufficient in the latter situation, it will be excessive when molding immediately after production, which will cause adhesion to the mold (mold deposit) and impair transparency due to the additive. ..

Further, even if the resin raw material is deoxidized immediately before extrusion molding, or if the inert gas is allowed to flow into the hopper provided in the molding apparatus, the amount of dissolved oxygen gas in the polycarbonate resin once increased during storage. Is difficult to reduce. According to the study by the present inventors, even if molding is performed based on the polycarbonate resin while the amount of dissolved oxygen gas in the polycarbonate resin is large, the obtained molded product is conspicuously colored in yellow (amber). It has become clear. For example, page 323 and FIG. 7.128 of Seiichi Honma's "Polycarbonate Resin Handbook" show the amount of oxygen absorbed by the polycarbonate resin by heat treatment at 140 ° C. The drying temperature of the polycarbonate resin before molding is 120 ° C., and it is generally interpreted that oxygen is taken into the resin by pre-molding drying. These measuring methods are described in the Journal of Applied Polymer Science Vol.10 P843-857, and measure the weight increase by a heat balance.

Further, it is disclosed in Japanese Patent Application Laid-Open No. 03-239508 that the thermoplastic resin is stored in a state where oxygen is blocked. However, even if it is possible to suppress the coloring of the thermoplastic resin with the passage of storage time and prevent the deterioration of the hue by blocking oxygen, it is not possible to improve the hue as compared with the production of the thermoplastic resin. Absent. Therefore, it is difficult to improve the essential hue of the thermoplastic resin only by improving the storage state.

As described above, it cannot always be said that the problem of transparency due to coloring of the molded product can be surely solved only by the method of suppressing the oxygen concentration contained in the polycarbonate resin. Therefore, it has been required to provide a method for producing a polycarbonate resin that can more reliably prevent coloring, and a polycarbonate resin that is sufficiently suppressed in coloring and has excellent transparency.

Japanese Unexamined Patent Publication No. 06-145337 Japanese Unexamined Patent Publication No. 05-331277 Special Table 2002-533544 Gazette Japanese Unexamined Patent Publication No. 06-145492 Japanese Unexamined Patent Publication No. 2009-029031 Japanese Unexamined Patent Publication No. 2001-08817 Japanese Unexamined Patent Publication No. 03-239508

Therefore, the present invention manufactures polycarbonate resin pellets, extrusion-molded products, and injection-molded products, which have negligibly little yellow (amber) coloring and high transparency, and the polycarbonate resin pellets and molded products. The challenge is to provide a method.

The present inventors have solved the above-mentioned problems by a method for producing pellets in which fine powders are removed from the powder or granular material of a polycarbonate resin to obtain sorted granules and pellets are formed using the sorted granules. It came to. That is, the present invention is as follows.

<1> A method of molding a polycarbonate resin to manufacture a molded product.
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B) Having any of the following steps
(B1) Pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form pellets:
(B2) Pellet extrusion step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets and extruding the pellets to produce an extruded product:
(B3) Pellet injection step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets, and injection molding the pellets to produce an injection molded product:
(B4) Extrusion step of extruding the sorted granules to produce an extruded product: or
(B5) An injection step of producing an injection-molded product by injection-molding the sorted granules.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the obtained molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is A method for producing a polycarbonate resin molded product having a weight of 5 ppm or less.

<2> The content of the compound represented by the formula (A) in the decomposition product after alkaline hydrolysis of the sorted granules is 3 ppm by weight or less, or the content of the compound represented by the formula (B). The production method according to <1> above, wherein the amount is 3 ppm by weight or less.
<3> In the above <1> or <2>, the (a) granule sorting step is a step of obtaining sorted granules having a particle size of 500 μm or more and a content of 90% by weight or more. The manufacturing method described.
<4> The above-mentioned <1> to <3>, wherein the solution YI value of the sorted granules is 0.05 or more smaller than the solution YI value of the powder or granular material before obtaining the sorted granules. Manufacturing method.
<5> The production method according to any one of <1> to <4>, wherein in the (a) granule sorting step, the sorted granules are obtained from the powder or granular material by using wind power.
<6> The production method according to <5> above, wherein the suspended fine powder is removed by using a blowing means to obtain the selected granules.
<7> The production method according to any one of <1> to <4> above, wherein in the (a) granule sorting step, the sorted granules are obtained from the powder or granular material using a sieve.
<8> The production method according to <7> above, wherein the fine powder is removed while the sieve is vibrating to obtain the sorted granules.
<9> The production method according to any one of <1> to <8> above, wherein the solution YI value of the sorted granules is 1.30 or less.
<10> The production method according to any one of <1> to <9> above, wherein the solution YI value of the produced molded product is 2.00 or less.
<11>
In the pellet forming step (b1), the selected granules are melted to form pellets in an atmosphere where the oxygen concentration is 10,000 ppm or less by adding an inert gas and / or reducing the pressure. The manufacturing method according to any one of.
<12> The production method according to any one of <1> to <11> above, wherein the pellet formed by the pellet forming step (b1) is sealed in a state where the surface temperature of the pellet is 50 to 100 ° C.
<13> Any of the above <1> to <12>, in which the pellets formed by the pellet forming step (b1) are stored in an atmosphere in which the oxygen concentration is reduced to 10,000 ppm or less by adding an inert gas and / or reducing the pressure. The manufacturing method described in Crab.
<14> The production method according to any one of <1> to <13> above, wherein the solution YI value of the pellet is 1.40 or less.
<15>
The production method according to any one of <1> to <14> above, wherein the dissolved oxygen concentration in the pellet is 0.015 cm ³ / g or less, and the water content in the pellet is 300 ppm or less.
<16> Prior to the (b2) pellet extrusion step or the (b3) pellet injection step, the pellets are heated in a state of being sealed by a packaging means so that the surface temperature of the pellets is 60 ° C. or higher. The production method according to any one of <1> to <15>.
<17> In the (b2) pellet extrusion step or the (b3) pellet injection step, the pellet is extrusion-molded or injection-molded in an atmosphere where the oxygen concentration is 1000 ppm or less by adding an inert gas and / or reducing the pressure. The manufacturing method according to any one of <1> to <16> above, which manufactures a molded product.
<18> In the (b4) extrusion step or the (b5) injection step, the sorted granules are extruded or injection-molded in an atmosphere where the oxygen concentration is 10,000 ppm or less by adding an inert gas and / or reducing the pressure. The manufacturing method according to <1> to <17> above, which manufactures a molded product.
<19>
The production method according to <1> to <18> above, wherein the sorted granules before injection molding are dried to have a water content of 200 ppm or less.
<20>
The molded product is a pellet,
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B1) has a pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form pellets.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the pellet is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5 ppm by weight. The production method according to <1>, which is described below.

<21>
The molded product is an extruded product,
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B2) A pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets.
It has a pellet extrusion step of extruding the pellet to produce an extruded product.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The production method according to <1> above, wherein the weight is ppm or less.

<22>
The molded product is an injection molded product,
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B3) A pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets.
It has a pellet injection process for producing an injection-molded product by injection-molding the pellets.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The production method according to <1> above, wherein the weight is ppm or less.

<23>
The molded product is an extruded product,
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B4) It has an extrusion step of extruding the sorted granules to produce an extruded product.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The production method according to <1> above, wherein the weight is ppm or less.

<24>
The molded product is an injection molded product,
(A) A granule sorting step of obtaining a sorted granule from which fine powder is removed from a polycarbonate resin powder obtained by an interfacial polymerization method.
(B5) It has an injection step of producing an injection-molded product by injection-molding the sorted granules.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The production method according to <1> above, wherein the weight is ppm or less.

<25>
A molded product formed from powders and granules of a polycarbonate resin obtained by an interfacial polymerization method.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the obtained molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is A molded product of polycarbonate resin having a weight of 5 ppm or less.
<26>
The molded product
Polycarbonate resin pellets formed from polycarbonate resin powders and granules obtained by an interfacial polymerization method.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the pellet is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5 ppm by weight. The molded product according to <25> above, which is as follows.

<27>
The molded product according to <26> above, wherein the solution YI value of the pellet is 1.40 or less.
<28> The molded product according to <26> or <27> above, wherein the dissolved oxygen concentration in the pellet is 0.015 cm ³ / g or less.
<29> The molded product according to any one of <26> to <28> above, wherein the water content in the pellet is 300 ppm or less.
<30>
The molded product according to any one of <25> to <29>, wherein the solution YI value of the molded product is 2.00 or less.
<31> The molded product according to any one of <25> to <30> above, wherein the parallel light transmittance at a wavelength of 400 nm is 40% / 300 mm or more.
<32>
The molded product
An extrusion-molded product produced by removing fine powder from the polycarbonate resin powder or granules obtained by the interfacial polymerization method and extruding pellets formed by melting the selected granules. There,
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The molded product according to <25> above, which has a weight of ppm or less.

<33>
The molded product
An injection-molded product produced by removing fine powder from the polycarbonate resin powder or granules obtained by the interfacial polymerization method, and injecting and molding pellets formed by melting the selected granules. There,
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The molded product according to <25> above, which has a weight of ppm or less.

<34>
The molded product
An extrusion-molded product produced by removing fine powder from the polycarbonate resin powder or granular material obtained by the interfacial polymerization method and extruding the selected granular material.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The molded product according to <25> above, which has a weight of ppm or less.

<35>
The molded product
An injection-molded product produced by removing fine powder from a polycarbonate resin powder or granular material obtained by an interfacial polymerization method and injection-molding the selected granular material.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection molded product is 5 ppm by weight or less, or the content of the compound represented by the following formula (B) is 5. The molded product according to <25> above, which has a weight of ppm or less.

In the present invention, a sorted granule obtained by removing fine powder from the powder granule of the polycarbonate resin obtained by the interfacial polymerization method is obtained (grain sorting step), and further, any of the following steps, that is, the sorted granule A step of melting and forming pellets (pellet forming step), a step of extruding pellets formed using sorted granules to produce an extruded product (pellet extrusion step), and forming using sorted granules. The process of injecting pellets to produce an injection-molded product (pellet injection process), the process of extruding sorted granules to produce an extruded product (extruded process), and the process of injecting sorted granules for injection molding. A molded product such as a polycarbonate resin pellet can be produced by any of the steps (injection process) of producing the product. The content of the compound represented by the above formula (A) in the decomposition product after alkaline hydrolysis of the molded product produced in this manner is 5 ppm by weight or less, or the content of the compound represented by the above formula (B). The amount is 5 ppm by weight or less, and the molded product of the polycarbonate resin has high transparency with negligible yellow (amber) coloring.

It is a figure which shows the outline of the measurement method of the solution YI value. It is a figure which shows the 1st extrusion molding machine used for pellet formation. It is a figure which shows the 2nd extrusion molding machine used for pellet formation. It is a figure which shows the 1st injection molding machine used for manufacturing an injection molded article. It is sectional drawing of the mold assembly used for manufacturing an injection-molded article. It is a figure which shows the 2nd injection molding machine used for manufacturing an injection molded article.

1. 1. Polycarbonate Resin Powder Granules The polycarbonate resin powder granules in the present invention are produced by an interfacial polymerization method.
Specifically, the polycarbonate resin includes an aromatic dihydroxy compound or a small amount of the polyhydroxy compound, carbonyl chloride generally known as phosgene, or a carbonic acid diester typified by dimethyl carbonate or diphenyl carbonate, or carbon monoxide. It is obtained by reacting with a carbonyl compound such as carbonic acid or carbonic acid. The polycarbonate resin in the present invention is a polymer or copolymer of a thermoplastic aromatic polycarbonate which may be linear or branched.

Examples of the raw material aromatic dihydroxy compound include 2,2-bis (4-hydroxyphenyl) propane [= bisphenol A], 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and 2, 2-Bis (4-hydroxy-3,5-diethylphenyl) propane, 2,2-bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3, 5-dibromophenyl) propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4'-dihydroxy-diphenylmethane, bis- (4-hydroxyphenyl) methane, bis- (4-hydroxy-5-nitrophenyl) ) Methan, 1,1-bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone , 2,4'-Dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, 4,4'-dihydroxy-2 , 5-Diethoxydiphenyl ether, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1-phenyl-1,1-bis Examples thereof include (4-hydroxy-3-methylphenyl) ethane, but bis (4-hydroxyphenyl) alkanes are preferable, and 2,2-bis (4-hydroxyphenyl) propane is particularly preferable. [Called bisphenol A]. These aromatic dihydroxy compounds can be used alone or in combination of two or more.

To obtain branched polycarbonates, fluoroglusin, 4,6-dimethyl-2,4,6-tris (4-hydroxyphenyl) heptene-2,4,6-dimethyl-2,4,6-tris (4-hydroxy) Phenyl) heptene, 2,6-dimethyl-2,4,6-tris (4-hydroxyphenyl) heptene-3,1,3,5-tris (4-hydroxyphenyl) benzene, 1,1,1-tris ( Polyhydroxy compound represented by 4-hydroxyphenyl) ethane or the like, or 3,3 bis (4-hydroxyaryl) oxyindole (= isatin bisphenol), 5-chloroisatin bisphenol, 5,7-dichloroisatin bisphenol. , 5-Bromisatin bisphenol or the like may be used as a part of the above-mentioned aromatic dihydroxy compound, and the amount used is, for example, 0.01 to 10 mol%, preferably 0.1 to 2 mol%.

In the reaction by the interfacial polymerization method, the pH is usually kept at 10 or more in the presence of an organic solvent inert to the reaction and an alkaline aqueous solution, and an aromatic dihydroxy compound, a molecular weight modifier (terrest stop agent), and an aromatic if necessary. An antioxidant or the like for antioxidant of the group dihydroxy compound is used. Then, after reacting an aromatic dihydroxy compound or the like with phosgene, a polymerization catalyst such as a tertiary amine or a quaternary ammonium salt is added, and interfacial polymerization is carried out to produce a polycarbonate resin. The timing of addition of the molecular weight modifier is not particularly limited as long as it is between the time of phosgenation and the start of the polymerization reaction. The reaction temperature is, for example, 0 to 35 ° C., and the reaction time is, for example, several minutes to several hours.

Examples of the organic solvent inert to the reaction include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, monochlorobenzene and dichlorobenzene, and aromatic hydrocarbons such as benzene, toluene and xylene. .. Examples of the molecular weight modifier or terminal terminator include compounds having a monovalent phenolic hydroxyl group, specifically, m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, p. Examples thereof include -tert-butylphenol and p-long-chain alkyl-substituted phenol. As the polymerization catalyst, tertiary amines such as trimethylamine, triethylamine, tributylamine, tripropylamine, trihexylamine, and pyridine; quaternary ammonium salts such as trimethylbenzylammonium chloride, tetramethylammonium chloride, and triethylbenzylammonium chloride, etc. Can be mentioned.

The powder or granular material (flake) of the polycarbonate resin is produced by, for example, the following method. It is produced by dropping a dichloromethane solution containing a polycarbonate resin obtained by an interfacial polymerization method into warm water maintained at about 45 ° C. and evaporating and removing the solvent. Alternatively, it is produced by putting a dichloromethane solution containing a polycarbonate resin by an interfacial polymerization method into methanol, filtering the precipitated polymer, and drying the precipitated polymer. Flake of polycarbonate resin is also produced by stirring and pulverizing a dichloromethane solution containing a polycarbonate resin by an interfacial polymerization method with a kneader while keeping the temperature at about 40 ° C., and then removing the solvent with hot water of 95 ° C. or higher. be able to.

The polycarbonate resin powder or granular material thus produced has, for example, an average particle size of about 50 to 300 μm, 300 to 500 μm, 500 to 700 μm, 700 to 900 μm, and is, for example, 600 μm, 800 μm, or the like. The particle size distribution of the powder or granular material is 50 to 1500 μm, 100 to 1500 μm, 200 to 1500 μm, 300 to 1500 μm, or the like.

2. 2. Powder Sorting Step In the grain sorting step, in the grain sorting step, fine powder, that is, fine powder having a particle size smaller than that of other granules contained in the powder or granular material is removed from the powder or granular material of the polycarbonate resin to sort the granular material. To get. This is because, as will be described later, the fine particles contained in the powder or granular material of the polycarbonate resin are colored yellow as compared with the larger particles, and tend to be inferior in hue. The sorted granules contain granules having a particle size of a predetermined reference particle size or more in a predetermined reference content or more, and for example, 90% by weight or more of granules having a particle size of 200 μm or more. The reference particle size and the reference content of the sorted granules are appropriately selected according to the particle size distribution of the powder or granular material to be used, the hue, and the like. For example, the standard particle size is 100 μm, 200 μm, 300 μm, 500 μm, 1000 μm, etc., and the standard content is 80% by weight, 90% by weight, 95% by weight, 97% by weight, or the like.

In the grain sorting step of the present invention, a sieve having a predetermined size of a mesh, a wind sorting machine using a blowing means, or the like can be used. In addition, a sieve and a wind power sorter or the like may be used together.

1) Sieve The fine powder can be removed by sieving the powder or granular material with a sieve having a predetermined size of opening. As such a sieve, for example, a JIS standard sieve (JIS Z 8801-1) of a metal net or a resin net can be used. However, a sieve that does not conform to JIS standards may be used. Further, a classification device provided with a sieve (net) may be used. In this case, fine powder can be efficiently removed from the powder or granular material by vibrating the sieve or the like.

2) Wind power sorter A wind power sorter having a blowing function may be used to remove fine powder while the powder or granular material is suspended by blowing air. In the wind power sorter, for example, a blower (blower means) installed below the cylinder generates an upward wind in the cylinder while suspending the powder or granular material. At this time, the fine powder is blown by the wind force, passes through the cylinder, and reaches the diffusion chamber connected to the cylinder, whereas the powder having a larger particle size and heavier than the fine powder is caused by gravity even if it is temporarily suspended. Fall inside. As a result, the fine powder and the sorted granules having a larger particle size can be separated to obtain the sorted granules.
Moreover, the structure of the wind power sorter is not limited to this. For example, the inside of the system may be decompressed by a blower installed above the inside of the machine, and the sorted granules may be dropped while moving the fine powder into the decompression system. Further, the powder or granular material may be supplied to the air passage having the diffusion chamber, the fine powder may be suspended and sent to the diffusion chamber, and the sorted granules may be dropped near the supply port of the powder or granular material. The natural wind may be partially utilized.

In the present specification, the particle size of the sorted granules is determined based on the value of the nominal opening (mm) of JIS Z8801-1. For example, a particle having a nominal opening of 200 μm and not passing through a sieve is defined as a particle having a particle size of 200 μm or more. When sorted granules are obtained using a sieve that does not conform to JIS standards or a wind power sorter, the sorted granules are then further sieved according to the JIS standard to obtain the above-mentioned reference particle size. And the standard content can be grasped.

3. 3. Sorted Granules In the present invention, the compound represented by the following formula (A) (hereinafter referred to as “Compound A”) in the decomposed product after alkaline hydrolysis of the sorted granules, or the following formula (B). The content of the compound (hereinafter referred to as "Compound B") is preferably 3 ppm by weight or less, more preferably 2 ppm by weight or less, and particularly preferably 1 ppm by weight or less. Further, the contents of compound A and compound B in the alkaline hydrolyzate of the sorted granules are both 3 ppm by weight or less, or the total content of compound A and compound B is 3 ppm by weight or less. Is more preferable. Further, the value of these contents is also more preferably 2 ppm by weight or less, and particularly preferably 1 ppm by weight or less. The method for measuring the content (concentration) of compound A in the decomposed product after alkaline hydrolysis of the sorted granules is the same as that for pellets described below.

4. Pellet forming step In the pellet forming step, in the pellet forming step, the above-mentioned sorted granules are melted under a predetermined temperature condition to form a pellet of a polycarbonate resin.

4-1. Pellet components In the pellet forming step, the following components can be added in addition to the selected granules of the polycarbonate resin. For example, release of antioxidants, phenol-based, phosphorus-based, sulfur-based heat stabilizers, benzotriazole-based and benzophenone-based ultraviolet absorbers, carboxylic acid esters, polysiloxane compounds, paraffin wax (polyolefin-based), polycaprolactone, etc. Examples thereof include a mold agent and an additive such as a light stabilizer.

Examples of the antioxidant include an organophosphorus compound such as a phenol-based antioxidant, a hindered phenol-based antioxidant, a bisphenol-based antioxidant, a polyphenol-based antioxidant, an organic sulfur compound, and phosphite. Specifically, as a phenolic antioxidant, 2,6-di-obutyl-4-methylphenol, n-octadecyl-3- (3', 5'-di-tert-butyl-4'-hydroxyphenyl) Propionate, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 4, 4'-butylidenebis- (3-methyl-6-tert-butylphenol), triethylene glycol-bis [3- (3-tert-butyl-hydroxy-5-methylphenyl) propionate], 3,9-bis {2- [3- (3-tert-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane be able to. In addition, as hindered phenolic antioxidants, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert) -Butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], N, N'-hexane-1,6-diylbis [3-) (3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (1,1-dimethyl) Ethyl) -4-hydroxyphenyl] methyl] phosphate, 3,3', 3 ", 5,5', 5" -hexa-tert-butyl-a, a', a "-(methicylene-2,4,6 -Triyl) tri-p-cresol, 4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate ], Hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3, 5-Triazin-2-ylamino) phenol and the like can be mentioned.

As a heat stabilizer, a phosphite ester compound (a) in which at least one ester in the molecule is esterified with phenol and / or a phenol having at least one alkyl group having 1 to 25 carbon atoms, phosphite (b). ) And tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylene-di-phosphonite (c), at least one selected from the group. Specific examples of the phosphite ester compound (a) include trioctylphosphite, tridecylphosphite, triphenylphosphite, trisnonylphenylphosphite, tris (octylphenyl) phosphite, and tris (2,4-di-). tert-butylphenyl) phosphite, tridecylphosphite, didecylmonophenylphosphite, dioctylmonophenylphosphite, diisopropylmonophenylphosphite, monobutyldiphenylphosphite, monodecyldiphenylphosphite, monooctyldiphenylphosphite, Distearyl pentaerythritol diphosphite, diphenylpentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, 2,2-methylenebis (4,6-di-) tert-butylphenyl) octylphosphite, bis (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl) -4-ethylphenyl) pentaerythritol diphosphite and the like can be mentioned. These may be used alone or in admixture of two or more.

Specific examples of the ultraviolet absorber include inorganic ultraviolet absorbers such as cerium oxide and zinc oxide, as well as organic ultraviolet absorbers such as benzotriazole compounds, benzophenone compounds and triazine compounds. Of these, organic UV absorbers are preferred. In particular, benzotriazole compounds, 2- (4,6-diphenyl-1,3,5-triazine-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4,6-bis (2,) 4-Dimethylphenyl) -1,3,5-triazine-2-yl] -5- (octyloxy) phenol, 2,2'-(1,4-phenylene) bis [4H-3,1-benzoxazine-4- On], [(4-methoxyphenyl) -methylene] -propanedioic acid-dimethyl ester is preferably at least one selected from the group. Specific examples of the benzotriazole compound include a condensate with methyl-3- [3-tert-butyl-5- (2H-benzotriazole-2-yl) -4-hydroxyphenyl] propionate-polyethylene glycol. .. Specific examples of other benzotriazole compounds include 2-bis (5-methyl-2-hydroxyphenyl) benzotriazole and 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2 -(3', 5'-di-tert-butyl-2'-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzo Triazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- (3,5-di-tert-amyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3 , 5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2'-methylene-bis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-) Benzotriazole 2-yl) phenol] [methyl-3- [3-tert-butyl-5- (2H-benzotriazole-2-yl) -4-hydroxyphenyl] propionate-polyethylene glycol] condensates and the like can be mentioned. it can. Two or more of these may be used in combination. Among the above, preferably 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl]- 2H-benzotriazole, 2- (4,6-diphenyl-1,3,5-triazine-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4,6-bis (2,4) -Dimethylphenyl) -1,3,5-triazine-2-yl] -5- (octyloxy) phenol, 2,2'-methylene-bis [4- (1,1,3,3-tetramethylbutyl)- 6- (2N-benzotriazol 2-yl) phenol].

Examples of the release agent include at least one compound selected from the group of aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds having a number average molecular weight of 200 to 15,000, and polysiloxane-based silicone oils. be able to. Examples of the aliphatic carboxylic acid include saturated or unsaturated aliphatic monovalent, divalent or trivalent carboxylic acids. Here, the aliphatic carboxylic acid also includes an alicyclic carboxylic acid. Among these, the preferred aliphatic carboxylic acid is a monovalent or divalent carboxylic acid having 6 to 36 carbon atoms, and an aliphatic saturated monovalent carboxylic acid having 6 to 36 carbon atoms is more preferable. Specific examples of aliphatic carboxylic acids include palmitic acid, stearic acid, caproic acid, caproic acid, lauric acid, araquinic acid, bechenic acid, lignoceric acid, cerotic acid, melissic acid, tetraliacontanic acid, montanic acid, adipic acid, Azelaic acid and the like can be mentioned. As the aliphatic carboxylic acid in the ester of the aliphatic carboxylic acid and the alcohol, the same one as the above-mentioned aliphatic carboxylic acid can be used. On the other hand, examples of the alcohol include saturated or unsaturated monohydric or polyhydric alcohols. These alcohols may have a substituent such as a fluorine atom or an aryl group. Among these, monohydric or polyhydric saturated alcohols having 30 or less carbon atoms are preferable, and aliphatic saturated monohydric alcohols or polyhydric alcohols having 30 or less carbon atoms are more preferable. Here, the aliphatic compound also includes an alicyclic compound. Specific examples of alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, polypropylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol. And so on. The above ester compound may contain an aliphatic carboxylic acid and / or an alcohol as an impurity, or may be a mixture of a plurality of compounds. Specific examples of esters of aliphatic carboxylic acid and alcohol include beeswax (mixture containing myricyl palmitate as the main component), stearyl stearate, behenyl behenate, stearyl behenate, glycerin monopalmitate, and glycerin monostearate. , Glycerin distearate, glycerin tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate and the like. Examples of the aliphatic hydrocarbon having a number average molecular weight of 200 to 15,000 include liquid paraffin, paraffin wax, microwax, polyethylene wax, Fischer-Tropsch wax, and α-olefin oligomer having 3 to 12 carbon atoms. Here, the aliphatic hydrocarbon also includes an alicyclic hydrocarbon. Moreover, these hydrocarbon compounds may be partially oxidized. Among these, paraffin wax, polyethylene wax or a partial oxide of polyethylene wax is preferable, and paraffin wax and polyethylene wax are more preferable. The number average molecular weight is preferably 200 to 5000. These aliphatic hydrocarbons may be a single substance or a mixture of various constituents and molecular weights, and the main component may be within the above range. Examples of the polysiloxane-based silicone oil include dimethyl silicone oil, phenyl methyl silicone oil, diphenyl silicone oil, and fluorinated alkyl silicone. Two or more of these may be used in combination.

Examples of the light stabilizer include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, ogizanilide-based ultraviolet absorbers, malonic acid ester-based ultraviolet absorbers, and hindered amines. Specific examples of the light stabilizer include 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2- ( 2-Hydroxy-5-tert-octylphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (5-methyl-2-hydroxyphenyl) ) Benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2,2'-methylenebis (4-cumyl-6-benzotriazolephenyl), Examples thereof include p-phenylenebis (1,3-benzoxazine-4-one) and [(4-methoxyphenyl) -methylene] -malonic acid dimethyl ester.

These additives may be added directly to the selected granules of the polycarbonate resin by directly mixing the total amount required by a tumbler, a mixer, etc., to form a masterbatch consisting of all kinds of additives, and to form pellets. May be used for. In addition, the required total amount of some types of additives may be mixed with each other to form a masterbatch for other additives.

4-2. Pellet formation In the pellet formation step, for example, pellets are formed by extrusion granulation using sorted granules. As an extruder suitable for use in this extrusion granulation, a well-known twin-screw machine including a vent type extruder and a tandem type extruder, a parallel type twin-screw extruder, and a well-known twin-screw machine including a conical type twin-screw extruder. An extruder or the like can be used. The structure, structure, type, etc. of the strand die are arbitrary. The heating cylinder is generally composed of a supply section (feed zone), a compression section (compression zone), and a quantification section (metering zone). A die is arranged downstream of the quantification section, and a hopper is provided in the supply section. It is attached. Depending on the extrusion molding machine used, the heating cylinder may have a closed structure and may be modified so that an inert gas can be introduced into the heating cylinder.

The selected granules of the polycarbonate resin charged into the hopper are sent to the compression section as solid in the supply section of the heating cylinder, and plasticization and melting proceed before and after the compression section. The sorted granules are then weighed in the weighing section and extruded through the strand die. The exhaust port (vent portion) may be provided in the compression portion or downstream thereof (for example, between the compression portion and the measuring portion). The type, structure, and configuration of the heating cylinder, screw, and hopper are essentially arbitrary, and known heating cylinders, screws, and hoppers can be used. In the case of continuously forming pellets, that is, granulating, it is necessary to carry the flaky sorted granules as a raw material into the hopper, and such a carrying method can be any method. For example, it is possible to use a method in which the pressure inside the hopper is negative and the sorted granules are carried into the hopper by airflow from the storage portion of the sorted granules via a pipe.

The melting temperature of the sorted granules for forming the pellets is adjusted according to the type of the sorted granules as the raw material (particularly the glass transition temperature, etc.), but is 145 ° C. or higher and 230 to 300 ° C. Is preferable.

4-3. Inert gas In the present invention, it is preferable to form pellets in an environment where the oxygen concentration is lower than that in the atmosphere by using an inert gas or by a depressurization step in order to suppress coloring of the pellets. Further, before using the inert gas, it is preferable to depressurize or evacuate the inside of the system in advance to remove oxygen. More specifically, the oxygen concentration is preferably 10,000 (volume) ppm (1%) or less, more preferably 5000 ppm or less, and most preferably 5000 ppm or less, by adding an inert gas, reducing the pressure in the system, or a combination thereof. In an atmosphere of 2000 ppm or less, the selected granules of the polycarbonate resin are melted to form pellets.

Examples of the inert gas include helium gas and argon gas, but it is economically preferable to use nitrogen gas. When nitrogen gas is used as the inert gas, a commercially available nitrogen gas cylinder, a separation membrane type or PSA type nitrogen gas generator, or the like can be used.

It is desirable that the inert gas flows from the inert gas source to the outside of the system via piping, a heating cylinder, and a hopper. In addition, the inert gas can be effectively used by flowing it toward the material bunker (storage). In this case, it is preferable that the portion of the heating cylinder through which the inert gas flows is airtight. However, if the pressure of the inert gas in the portion of the heating cylinder through which the inert gas flows is kept substantially constant, there may be some leakage of the inert gas from the portion of the heating cylinder in which the inert gas flows. Further, in this case, the hopper is filled with the sorted granules, and the inert gas flows from the portion of the heating cylinder to which the hopper is attached to the tip of the heating cylinder in a plasticized state. The pressure of the part is preferably higher than the atmospheric pressure. The pressure of the portion of the heating cylinder through which the inert gas flows is preferably, for example, about 2 × 10 ³ Pa (0.02 kgf / cm ² ) or higher than the atmospheric pressure. Further, the pressure in the hopper in which the sorted granules are charged in the extrusion molding machine or in the heating cylinder when the sorted granules are plasticized and melted should be set to a preferable level, for example, 1.3 × 10 ⁴ Pa or less. , May be depressurized by a vacuum pump.

The molten resin extruded from the extrusion molding machine may be formed into a strand shape, and pellets of the polycarbonate resin may be produced by using a strand cutter or the like. At this time, the strand-shaped molten resin is water-cooled. At the time of water cooling, adjusting the surface temperature of the cooled pellets to preferably 60 to 140 ° C., more preferably 80 to 120 ° C. is a viewpoint of preventing water retention in the pellets and preventing blocking of the molten pellets. Is preferable. However, pellets may be produced by air-cooling and cutting the strand-shaped molten resin.

5. Storage of pellets The pellets formed in the pellet forming step described above are subjected to addition of an inert gas, reduced pressure in the system, or a combination thereof to have an oxygen concentration of preferably 10,000 (volume) ppm or less, more preferably 5000 ppm. Hereinafter, storage in an atmosphere of 2000 ppm or less is most preferable in order to reduce the residual oxygen concentration. Further, it is preferable to store (seal) the pellets in a storage container in a state where the surface temperature of the pellets is preferably 50 to 100 ° C., more preferably 60 to 80 ° C. from the viewpoint of preventing water adsorption by the pellets.

Further, the pellets are preferably stored in a closed storage container or packed in a bag. Bag used in the closed storage containers or bagged, the oxygen permeability preferably ^{100cm 3 / (m 2 · 24h} · atm) or less, more preferably ^{10cm 3 / (m 2 · 24h} · atm) or less, even more preferably at ^{1cm 3 / (m 2 · 24h} · atm) or less, 40 ° C., preferably the water vapor permeability at ^{90% RH 10g / (m 2} · 24 hr) or less, more preferably 1 cm ³ / ( m ² · 24h · atm) is less than or equal to. Further, it may be stored in a closed container containing an oxygen gas absorber to reduce the oxygen concentration in the system.

In the present invention, the dissolved oxygen concentration in the pellet can be suppressed to preferably 0.015 cm ³ / g or less, more preferably 0.010 cm ³ / g or less by the above-mentioned method, and the water content in the pellet. Is preferably suppressed to 300 ppm by weight or less, more preferably 200 ppm by weight or less. As a result of suppressing the dissolved oxygen concentration in the pellets, it is possible to prevent coloring of the pellets during storage. Further, by suppressing the water content of the pellets during storage, molding defects such as foaming during subsequent injection molding of the pellets can be prevented, so that the pellet drying step can be omitted. In the drying step, the pellets generally occlude oxygen in the air, resulting in a decrease in hue (coloring). Therefore, by suppressing the water content of the pellets, the effect of indirectly maintaining a good hue can be obtained.

6. Treatment at the time of opening the pellet When opening the pellet sealed by the above-mentioned packaging means, it is preferable to perform the following treatment. First, with the pellets sealed in a closed storage container or bag, the surface temperature of the pellets is 60 ° C. or higher, more preferably 80 ° C. or higher, and 60 ° C. to 100 ° C., more preferably, together with the closed container or the like. Heat at 80 to 100 ° C. for 1 hour or longer, for example 4 hours. By raising the temperature of the pellets before they come into contact with the outside air in such a pre-opening treatment, it is possible to suppress the adsorption of water and the dissolution (occlusion) of oxygen gas in the pellets after opening.

Immediately after opening the sealed pellet, it is preferable to place the pellet in an atmosphere having an oxygen concentration of 1000 ppm or less, more preferably 500 ppm or less. This is to prevent the oxygen in the air from being dissolved in the pellets, and for this purpose, a hopper for purging an inert gas such as nitrogen gas, a vacuum hopper, or the like is used. Further, it is preferable to heat the pellets for the above-mentioned purpose not only before opening but also after opening. As described above, the extrusion produced by maintaining the surface temperature of the pellets at, for example, 60 ° C. or higher and the ambient oxygen concentration at, for example, 1000 ppm or lower from the time of opening until it is used for extrusion molding or injection molding. The hue of the molded product or the injection molded product can be further improved.

7. Compounds in Pellet Decomposed Products In the present invention, the decomposition products of polycarbonate resin pellets after alkali hydrolysis contain the compound A represented by the following formula (A) and the compound B represented by the following formula (B). The amounts are 5 ppm by weight or less, preferably 3 ppm by weight or less, more preferably 2 ppm by weight or less, and particularly preferably 1 ppm by weight or less. Further, the contents of compound A and compound B in the alkaline hydrolyzate of the pellets are both 5 ppm by weight or less, or the total content of compound A and compound B is 5 ppm by weight or less. Is more preferable. Further, the value of these contents is also preferably 3 ppm by weight or less, more preferably 2 ppm by weight or less, and particularly preferably 1 ppm by weight or less. In the present invention, the content of compound A can be kept low by removing fine powder from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method, and as a result, pellets having more excellent hue can be produced. it can.

The content (concentration) of compounds A and B in the decomposition product of the pellet after alkaline hydrolysis is measured using LC-MS / MS as follows. First, a 0.1 g pellet sample is dissolved in 10 ml of dichloromethane. To this dichloromethane solution, 1.8 ml of a methanol solution of 28% sodium methoxide, 8 ml of methanol, and 2.6 ml of water are added, and the mixture is stirred for 1 hour. To this solution, 12 ml of a 1N hydrochloric acid aqueous solution is added, and the mixture is stirred for 10 minutes to acidify the inside of the system and then allowed to stand. Then, the volume of the organic layer of dichloromethane separated from the aqueous layer is adjusted to 10 ml, and 2 ml of the dichloromethane solution is collected. This dichloromethane solution is dried under a nitrogen stream, and the obtained sample is dissolved in 2 ml of an acetonitrile solution of 10 mg / l of methoxysalicylic acid as an internal standard solution to prepare an LC-MS / MS measurement sample. The contents of compounds A and B in the alkaline hydrolyzate of the pellet are calculated by LC-MS / MS measurement on this measurement sample.

The content of compounds A and B in the alkaline hydrolyzate of the polycarbonate resin pellet is closely related to the hue of the pellet, as will be described in detail later. That is, the pellets having a low content of compounds A and B are almost colorless and have an excellent hue, whereas the pellets having a high content of compounds A or B are colored yellow or amber and have a hue. Tends to be inferior to. In the present invention, pellets having a good hue are produced by forming pellets using the sorted granules as described above, and the contents of compounds A and B in the alkaline hydrolyzate of the pellets are different, respectively. It can be suppressed to 5 wt ppm or less.

8. Hue of Polycarbonate Resin In the present specification, the hue of polycarbonate resin pellets, extrusion-molded products, injection-molded products, and powders and granules is evaluated by the solution YI value. Polycarbonate resins that are colored yellow (amber) by impurities have a larger solution YI value. The solution YI value is measured as follows. That is, a 15 wt% dichloromethane solution of polycarbonate resin is placed in a transparent container, and light from a C light source (1 mm × 3 mm) is transmitted through a 100 mm dichloromethane solution layer and received by a light receiving portion, and the transmittance calculated at this time is received. Is the solution YI value (see FIG. 1). A spectroscopic transmission color meter ASA-1 manufactured by Nippon Denshoku Industries Co., Ltd. was used for measuring the solution YI value in the specification of the present application. Hereinafter, in the present specification, the hue of pellets, powders and the like is expressed using the solution YI value.

In the powder or granular material of the polycarbonate resin, as illustrated in Table 1, the larger the particle size, the lower the solution YI value and the better the hue, while the smaller the particle size, the higher the solution YI value. It was revealed that it had and was colored. Based on the relationship between the particle size distribution and the hue of the powder or granular material, in the present invention, pellets having an excellent hue are formed by using the sorted granules obtained by removing the fine powder. It is preferable to use a sorted granule having a particle size of 500 μm or more and a content of 90% by weight or more, and particularly preferably a granular material having a particle size of 1 mm or more has a content of 90% by weight or more. Certain sorted granules are used to form pellets with excellent hue.

In the present invention, the solution YI value of the sorted granules is 0.05 or more, preferably 0.10 or more, more preferably 0.20 or more than the solution YI value of the powder or granular material before obtaining the sorted granules. , Small is preferred. Further, the solution YI value of the sorted granules is preferably 1.30 or less, more preferably 1.20 or less, and particularly preferably 1.00 or less, which is a pellet having a more colorless hue and a molded product. It is preferable from the viewpoint of manufacturing. The solution YI value of the pellet produced by the production method of the present invention is preferably 1.40 or less, more preferably 1.20 or less, and particularly preferably 1.00 or less.

9. Pellet Extrusion Step and Pellet Injection Step In the present invention, in the pellet extrusion step or the pellet injection step, the above pellets are extruded or pellet-injected to produce an extrusion-molded product of polycarbonate resin and an injection-molded product.

9-1. Components of Extruded Products and Injection Molded Products In the pellet extrusion step or pellet injection step, only the pellets of the polycarbonate resin may be extruded or injection molded, and the above-mentioned 4-1. Ingredients such as the additives listed in the pellet component column may be added to the pellet for extrusion or injection molding.

9-2. Manufacture of extruded products by pellet extrusion process In the pellet extrusion process, the above-mentioned 4-2. Extruded products are manufactured according to the method described in the section on pellet formation. That is, 4-2. Extruders of the types listed in the column for pellet formation can be used. As with extrusion molding for pellet formation, the die structure, configuration, type, etc. are arbitrary, and the heating cylinder generally has a supply section (feed zone), a compression section (compression zone), and a quantification section (meta). It is composed of a ring zone), a die is arranged downstream of the weighing unit, and a hopper is attached to the supply unit. Further, it is preferable that the heating cylinder has a closed structure and the inert gas can be introduced into the heating cylinder.

The pellets of the polycarbonate resin charged into the hopper are described in 4-2. Similar to the sorted granules in the column for forming pellets, in the supply section of the heating cylinder, the solid is sent to the compression section, plasticized and melted before and after the compression section, and extruded through the die. Then, the molten resin extruded from the extrusion molding machine is appropriately water-cooled or air-cooled and cut to produce an extrusion-molded product having a predetermined shape. The shape and size of the extruded product are not particularly limited, and for example, an extruded product having a width of 1000 mm, a thickness of 2 mm, and a length of 2000 mm can be obtained.

9-3. Manufacture of injection-molded product by pellet injection process In the pellet injection process, an injection-molded product is manufactured by injection molding using the pellets described above. As an injection molding machine suitable for this injection molding, for example, an in-line screw type injection molding machine can be mentioned. Further, an injection molding machine can also be used in which the rear end portion of the molding cylinder (heating cylinder) connecting the screw drive device and the screw has a sealed structure and the inert gas can be introduced into, for example, the sealed portion. A molding (heating) cylinder is generally composed of a supply section (feed zone), a compression section (compression zone), and a metering section (metering zone), and a die is arranged downstream of the metering section to supply the cylinder. A hopper is attached to the part.

The pellets of the polycarbonate resin charged into the hopper are described in 4-2. Similar to the sorted granules in the column for forming pellets, in the supply section of the heating cylinder, the solid is sent to the compression section, plasticized and melted before and after the compression section, and ejected through the resin lead-out section. .. In this way, the molten resin injected from the injection molding machine is supplied to the cavity of the mold and cooled to manufacture an injection-molded product having a shape corresponding to the shape of the cavity.

Also in the extrusion molding machine or injection molding machine used in the pellet extrusion process for manufacturing the extrusion-molded product or the injection-molded product, or the pellet injection process, the exhaust port (vent portion) is set to the compression part or its downstream (for example,). , Between the compression part and the measuring part). Even in this case, the type, structure, and configuration of the heating cylinder, screw, and hopper are essentially arbitrary, and known heating cylinders, screws, and hoppers can be used to continuously produce extruded products. , It is necessary to carry the pellets of the raw material into the hopper, and the carrying method can be any method. For example, the pressure inside the hopper may be negative, and the pellets may be carried into the hopper by airflow from the pellet storage portion via a pipe.

The melting temperature of pellets for producing extruded products or injection-molded products is adjusted according to the type of pellets as a raw material (particularly the glass transition temperature, etc.), but is 145 ° C. or higher and 230 to 300 ° C. Is preferable.

10. Extrusion Step and Injection Step In the present invention, in the extrusion step or injection step, the above-mentioned sorted granules can be extruded or injection-molded without passing through pellets to produce an extrusion-molded product or an injection-molded product of a polycarbonate resin. ..

10-1. Components of Extruded Products and Injection Molded Products In the extrusion process or injection process, the following components can be added in addition to the selected granules of the polycarbonate resin. For example, release of antioxidants, phenol-based, phosphorus-based, sulfur-based heat stabilizers, benzotriazole-based and benzophenone-based ultraviolet absorbers, carboxylic acid esters, polysiloxane compounds, paraffin wax (polyolefin-based), polycaprolactone, etc. Examples thereof include a mold agent and an additive such as a light stabilizer. Specific examples of additives that can be used in these extrusion steps or injection steps are similar to those described in paragraphs [0029] to [0034] above.

Further, it is preferable to reduce the water content by drying before using the sorted granules for injection molding. Specifically, the sorted granules are dried to suppress the water content in the sorted granules to preferably 300 ppm by weight or less, more preferably 200 ppm by weight or less. By suppressing the water content in the sorted granules, molding defects such as foaming during subsequent injection molding of the sorted granules can be prevented.

10-2. Manufacture of Extruded Products by Extrusion Step In the extrusion process, extruded products are manufactured by extrusion molding using sorted granules. As an extrusion molding machine suitable for this extrusion molding, for example, a well-known twin-screw extruder including a vent type extruder and a tandem type extruder, a parallel twin-screw extruder, and a well-known twin-screw extruder including a conical twin-screw extruder. Machines and the like can be used. Moreover, the structure, structure, form, etc. of the die are arbitrary. The heating cylinder is generally composed of a supply section (feed zone), a compression section (compression zone), and a quantification section (metering zone). A die is arranged downstream of the quantification section, and a hopper is provided in the supply section. It is attached. Depending on the extrusion molding machine used, the heating cylinder may have a closed structure and may be modified so that an inert gas can be introduced into the heating cylinder.

The selected granules of the polycarbonate resin charged into the hopper are sent to the compression section as solid in the supply section of the heating cylinder, and plasticization and melting proceed before and after the compression section. Then, the sorted granules are weighed by the weighing unit and extruded through the die. In this way, the molten resin extruded from the extrusion molding machine is appropriately cooled by contact with a mold such as a cooling roll and cut to produce an extrusion-molded product having a predetermined shape. The shape and size of the extruded product are not particularly limited, and for example, an extruded product having a width of 1600 mm, a thickness of 2 mm, and a length of 2000 m can be obtained.

The exhaust port (vent portion) may be provided in the compression portion or downstream thereof (for example, between the compression portion and the measuring portion). The type, structure, and configuration of the heating cylinder, screw, and hopper are essentially arbitrary, and known heating cylinders, screws, and hoppers can be used. For example, in the case of continuously producing an extruded product, it is necessary to carry the flaky sorted granules as a raw material into the hopper, and such a carrying method can be any method. For example, it is possible to use a method in which the pressure inside the hopper is negative and the sorted granules are carried into the hopper by airflow from the storage portion of the sorted granules via a pipe.

10-3. Manufacture of injection-molded products by injection process In the injection process, injection-molded products are manufactured by injection molding using sorted granules. As an injection molding machine suitable for this injection molding, for example, an in-line screw type injection molding machine can be mentioned. Further, an injection molding machine can also be used in which the rear end portion of the molding cylinder (heating cylinder) connecting the screw drive device and the screw has a sealed structure and the inert gas can be introduced into, for example, the sealed portion. A molding (heating) cylinder is generally composed of a supply section (feed zone), a compression section (compression zone), and a metering section (metering zone), and a die is arranged downstream of the metering section to supply the cylinder. A hopper is attached to the part.

The selected granules of the polycarbonate resin charged into the hopper are sent to the compression section as solid in the supply section of the molding cylinder, and plasticization and melting proceed before and after the compression section. Then, the sorted granules are weighed in the quantification section and ejected through the resin lead-out section. In this way, the molten resin injected from the injection molding machine is supplied to the cavity of the mold and cooled to manufacture an injection-molded product having a shape corresponding to the shape of the cavity.

The exhaust port (vent portion) may be provided in the compression portion or downstream thereof (for example, between the compression portion and the measuring portion). The type, structure, and configuration of the molding cylinder, screw, and hopper are essentially arbitrary, and known molding cylinders, screws, and hoppers can be used. For example, in the case of continuously producing an injection-molded product, it is necessary to carry the flaky sorted granules as a raw material into the hopper, and the carrying-in method can be any method. For example, it is possible to use a method in which the pressure inside the hopper is negative and the sorted granules are carried into the hopper by airflow from the storage portion of the sorted granules via a pipe.

The melting temperature of the sorted granules for producing an extruded product or an injection molded product is adjusted according to the type of the sorted granules as a raw material (particularly the glass transition temperature), but is 145 ° C. or higher, 230. It is preferably about 300 ° C.

11. Inert gas in pellet extrusion step or pellet injection step Also in the pellet extrusion step or pellet injection step, extrusion molding is carried out in an environment where the oxygen concentration is lower than that in the atmosphere by using inert gas or decompression step. It is preferable to suppress the coloring of the product or the injection-molded product. More specifically, the oxygen concentration is preferably 1000 (volume) ppm (1%) or less, more preferably 500 ppm or less, and most preferably 500 ppm or less, by adding an inert gas, reducing the pressure in the system, or a combination thereof. An extrusion-molded product or an injection-molded product is manufactured by melting the pellets of the polycarbonate resin in an atmosphere of 200 ppm or less.

For example, an inert gas is supplied into the system from an extrusion molding machine, which will be described in detail later, or a hopper and a rear end of a screw of an injection molding machine, and the oxygen concentration in the hopper is set to 1000 ppm or less, more preferably 500 ppm or less. The oxygen concentration at the rear end of the screw is 1000 ppm or less, more preferably 500 ppm or less. For this purpose, for example, an inert gas flow rate of 20 to 150 liters / minute is secured in the upper part of the hopper and 10 to 50 liters / minute is secured in the rear end of the screw. Also in the pellet extrusion step or the pellet injection step, the above-mentioned 4-2. An inert gas such as nitrogen gas exemplified in the column of inert gas can be used.

12. Inert gas in extrusion step or injection step In the extrusion step or injection step of the present invention, an extruded product or injection in an environment where the oxygen concentration is lower than in the atmosphere by using an inert gas or by a depressurization step. It is preferable to produce a molded product in order to suppress coloring of the extruded product or the injection molded product. Further, before using the inert gas, it is preferable to depressurize or evacuate the inside of the system in advance to remove oxygen. More specifically, the oxygen concentration is preferably 10000 (volume) ppm (1%) or less, more preferably 5000 ppm or less, most preferably 5000 ppm or less, by adding an inert gas, reducing the pressure in the system, or a combination thereof. A molded product is manufactured by extrusion molding or injection molding of the selected granules of the polycarbonate resin in an atmosphere of 2000 ppm or less.

Examples of the inert gas include helium gas and argon gas, but it is economically preferable to use nitrogen gas. When nitrogen gas is used as the inert gas, a commercially available nitrogen gas cylinder, a separation membrane type or PSA type nitrogen gas generator, or the like can be used.

It is desirable that the inert gas flows from the inert gas source to the outside of the system via piping, a heating cylinder, and a hopper. In addition, the inert gas can be effectively used by flowing it toward the material bunker (storage). In this case, it is preferable that the portion of the heating cylinder through which the inert gas flows is airtight. However, if the pressure of the inert gas in the portion of the heating cylinder through which the inert gas flows is kept substantially constant, there may be some leakage of the inert gas from the portion of the heating cylinder in which the inert gas flows. Further, in this case, the hopper is filled with the sorted granules, and the inert gas flows from the portion of the heating cylinder to which the hopper is attached to the tip of the heating cylinder in a plasticized state. The pressure of the part is preferably higher than the atmospheric pressure. The pressure of the portion of the heating cylinder through which the inert gas flows is preferably, for example, about 2 × 10 ³ Pa (0.02 kgf / cm ² ) or higher than the atmospheric pressure. Further, the pressure in the hopper in which the sorted granules are charged in the extrusion molding machine or in the heating cylinder when the sorted granules are plasticized and melted should be set to a preferable level, for example, 1.3 × 10 ⁴ Pa or less. , May be depressurized by a vacuum pump.

13. Compounds in Extruded Products and Decomposed Products of Injection Molded Products In the present invention, in the extruded products of polycarbonate resin or the decomposed products after alkaline hydrolysis of the injection molded products, the compound A represented by the following formula (A) The content of the compound B represented by the following formula (B) is 5 wt ppm or less, preferably 3 wt ppm or less, more preferably 2 wt ppm or less, and particularly preferably 1 wt ppm or less. Further, the contents of compound A and compound B in the alkaline hydrolyzate of the molded product are both 5 ppm by weight or less, or the total content of compound A and compound B is 5 ppm by weight or less. Is more preferable. Further, the value of these contents is also preferably 3 ppm by weight or less, more preferably 2 ppm by weight or less, and particularly preferably 1 ppm by weight or less. In the present invention, the content of the compounds A and B can be kept low by removing the fine powder from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method, and as a result, the extruded product having more excellent hue can be obtained. And injection molded products can be manufactured.

The content (concentration) of compounds A and B in the decomposition product of the extruded product or the injection-molded product after alkali hydrolysis is measured using LC-MS / MS as follows. First, 0.1 g of an extruded product or a sample of an injection molded product is dissolved in 10 ml of dichloromethane. To this dichloromethane solution, 1.8 ml of a methanol solution of 28% sodium methoxide, 8 ml of methanol, and 2.6 ml of water are added, and the mixture is stirred for 1 hour. To this solution, 12 ml of a 1N hydrochloric acid aqueous solution is added, and the mixture is stirred for 10 minutes to acidify the inside of the system and then allowed to stand. Then, the volume of the organic layer of dichloromethane separated from the aqueous layer is adjusted to 10 ml, and 2 ml of the dichloromethane solution is collected. This dichloromethane solution is dried under a nitrogen stream, and the obtained sample is dissolved in 2 ml of an acetonitrile solution of 10 mg / l of methoxysalicylic acid as an internal standard solution to prepare an LC-MS / MS measurement sample. The contents of compounds A and B in the alkali hydrolyzate of the extruded product or the injection molded product are calculated by LC-MS / MS measurement with respect to this measurement sample.

The content of compounds A and B in the alkali hydrolyzate of the extruded product or injection molded product of the polycarbonate resin is closely related to the hue of the extruded product or injection molded product, as will be described in detail later. That is, the extruded product or injection-molded product having a low content of compounds A and B is almost colorless and has an excellent hue, whereas the extruded product or injection-molded product having a high content of compounds A or B is almost colorless. It is colored yellow or amber and tends to be inferior in hue. In the present invention, as described above, by producing an extrusion-molded article or an injection-molded article from pellets formed using the sorted granules (pellet extrusion step or pellet injection step), or directly from the sorted granules. By producing an extrusion or injection molding (extrusion step or injection step), the hue of the extrusion or injection molding is good and in the extrusion or injection molded product alkali hydrolyzate. The contents of compounds A and B are each suppressed to 5 wt ppm or less.

14. Properties of Extruded Products and Injection Molded Products By using the above-mentioned sorted granules, the solution YI values of the extruded products and injection molded products formed from pellets can also be suppressed to low values. More specifically, the solution YI value of the extruded product and the injection-molded product produced by the pellet extrusion step of the production method of the present invention or the pellet injection step is 2.00 or less, preferably 1.80 or less. , More preferably 1.60 or less.

Further, the solution YI value of the extruded product or the injection-molded product formed by using the above-mentioned sorted granules can also be suppressed to a low value. More specifically, the solution YI value of the extruded product produced by the extrusion step of the production method of the present invention is 2.00 or less, preferably 1.40 or less, more preferably 1.20 or less, particularly. It is preferably 1.00 or less. The solution YI value of the injection-molded article produced by the injection step of the production method of the present invention is 2.00 or less, preferably 1.80 or less, and more preferably 1.60 or less.

In the extruded product and the injection-molded product formed from the pellets of the present invention, when the C light source is used as the light source, the parallel transmittance of the extruded product or the injection-molded product having a thickness of 300 mm at a wavelength of 400 nm is 40% or more. (40% / 300 mm or more), preferably 45% / 300 mm or more, and more preferably 50% / 300 mm or more.

In the extruded product directly formed from the selected granules of the present invention, when a C light source is used as the light source, the parallel transmittance of the extruded product having a thickness of 300 mm at a wavelength of 400 nm is 40% or more (40% / 300 mm). The above), preferably 50% / 300 mm or more, and more preferably 55% / 300 mm or more. Further, in the injection-molded product directly formed from the selected granules of the present invention, when a C light source is used as the light source, the parallel transmittance of the injection-molded product having a thickness of 300 mm at a wavelength of 400 nm is 40% or more (40%). / 300 mm or more), preferably 45% / 300 mm or more, and more preferably 50% / 300 mm or more.

Hereinafter, the present invention will be described based on preferred examples with reference to the drawings, but the present invention is not limited to these examples, and various numerical values and materials in these examples are examples.

[Impurities and hues in resin]
In order to investigate the relationship between impurities and hue in the polycarbonate resin obtained by the interfacial polymerization method, for each of the three types of polycarbonate resins I to III, a powder having a particle size of 100 μm or less and a powder having a particle size of 1 mm or more Granules were selected and used as Samples 1-6. The impurity concentrations and hues of these samples 1 to 6 were compared.

Alkaline hydrolysis of these samples 1 to 6 was carried out, and impurities contained in the samples 1 to 6 were identified and quantified by LC-MS / MS measurement or the like on the decomposed products. As a result, compound A represented by the formula (A) was detected as an impurity. However, although it was confirmed that the main component of the impurity was compound A, it is possible that compound B represented by the formula (B) was also contained in the above-mentioned impurities, albeit in a trace amount. These compounds were considered to be components derived from the branched chains of the polycarbonate resin.

As is clear from Table 2, Compound A was found to be closely related to the hues of Samples 1-6. That is, compound A was not detected in the sample having a higher YI value and a higher concentration of compound A and a lower YI value, specifically, a sample having a solution YI value of 1.35 or less. Therefore, in the present invention, as one of the requirements of the method for producing pellets, the requirement that the content of compound A in the pellets of the produced polycarbonate resin is not more than a predetermined amount is defined.

Further, from the results shown in Table 2 above, in the polycarbonate resin, the smaller the particle size of the powder or granular material, the higher the YI value and the coloration, and the larger the particle size of the powder or granular material, the lower the YI value and the superior hue. The point was confirmed.

(I. Pellet production)
In this example, first, from the powder or granular material (particle size distribution 50 to 1200 μm, average particle size 800 μm, solution YI value 1.33) of a common polycarbonate resin (H-4000F manufactured by Mitsubishi Engineering Plastics Co., Ltd.), it is yellow. The solution YI value and the concentration of the compound A were measured for each sample of the selected granules shown in Table 3 below from which the fine powder which is the main cause of the coloring of the material was removed.

The sorted granules of Samples 1 to 4 were obtained by removing fine powder from the powder granules of the resin using sieves having different mesh size. On the other hand, for the sorted granules of sample 5, fine powder is removed from the powder granules of the above resin by using a classification device (manufactured by Freund Turbo Co., Ltd .: turbo screener) capable of automatically sorting the powder granules. Obtained by doing.

The sorted granules of Sample 5 were sorted by a classifier as follows. First, a blade in a cylindrical net made of synthetic fiber with a mesh of 500 mesh provided in the classifier was rotated at high speed. In this state, by sucking air with a suction device (blower means), powder or granular material was supplied together with air from the end opening of the cylindrical net to the inside of the cylinder, and micro-vibration was generated in the net.
As a result, most of the powders having a small particle size passed through the side surface of the cylindrical net relatively quickly and fell, whereas the sorted granules that did not pass through the net and the powder having a slightly smaller amount were powders. It moved to the end opposite to the opening where the granules were supplied and fell through the opening.

By using such a classification device, the sorted granules of Sample 5 contained a small amount of powder having a small particle size. That is, while the samples 1 to 4 do not contain fine powder having a particle size equal to or smaller than the size of the opening of each sieve used, the selected particles of the sample 5 contain particles having a particle size of less than 500 μm. , About 3 to 5% by weight was contained based on the total weight of the sorted granules. As described above, by using the classification device, although a small amount of powder or granular material having a small particle size is contained in the selected granules, a large amount of powder or granular material can be sorted by utilizing centrifugal force. The comparative sample 1 is the unsorted powder or granular material of the above resin.

Comparing the hues of Samples 1 to 5 and Comparative Sample 1 with the concentrations of Compound A, it was confirmed that the sample from which more fine powder was removed had a smaller solution YI value and a better hue. Regarding compound A, undetected samples 3 to 5 having particularly good hues were observed, and samples 1 and 2 having good hues detected an amount of less than 3 ppm by weight, whereas in comparative sample 1, 4 was observed. It was confirmed that the detected amount was as large as 0.0 wt ppm. Thus, it was also confirmed that the concentration of compound A was related to the solution YI value. In Table 3, compound A tends to be detected even in the sample of the sorted granules having a lower solution YI value than the resin sample in Table 2. It is considered that this is due to the fact that the compound A is an index representing the impurities in the polycarbonate resin, but impurities other than the compound A are also present.

Next, pellets were formed using the selected granules of Sample 2 described above. An extrusion molding machine (extrusion granulator) 100 shown in FIG. 2 was used for forming the pellets. The extrusion molding machine 100 includes a heating cylinder 10 having a strand die 11 at its tip, a screw 15 built in the heating cylinder 10, a hopper 20 for supplying the selected granules 40 of raw materials into the heating cylinder 10, and a hopper 20. It has a screw drive device 18 or the like attached to the rear end portion 16 of the screw 15. The screw 15 arranged in the heating cylinder 10 plasticizes and melts the sorted granules 40. A heater (not shown) is attached to the outer periphery of the heating cylinder 10, and the sorted granules 40 existing in the gap 17 between the heating cylinder 10 and the screw 15 can be plasticized and melted. The sorted granular material 40 and the additive (not shown) described later were carried into the hopper 20 from the resin storage section via a pipe (not shown) and a carry-in section 21. The compositions of the sorted granules 40 and the additives used are as follows.
Sorted Granules 40 (Sample 2, Polycarbonate Resin Upiron H-4000F (manufactured by Mitsubishi Engineering Plastics): 99.92 parts by weight ADEKA STAB PEP36 (Bis (2,6-di-tert-butyl-4-ethylphenyl) penta) Eris Ritol Diphosphite Adeka): 0.05 parts by weight Rikemar S100A (glycerin monostearate, made by RIKEN Vitamin): 0.03 parts by weight

An inert gas discharge unit 24 having a check valve 23 is provided downstream of the exhaust unit 22 provided in the hopper 20 so that the pressure in the material supply path does not rise abnormally, and further downstream thereof, for example, the blower 25. The blower 25 was operated to create a negative pressure in the hopper 20, and the flake-shaped sorted granules 40 were carried into the hopper 20 from the raw material polycarbonate resin storage section via the pipe and the carry-in section 21. However, the method of carrying the sorted granules 40 from the resin storage unit to the hopper 20 can be any method.

The sorted granules 40 carried into the heating cylinder 10 from the hopper 20 were heated, plasticized, melted, and conveyed by the heating cylinder 10 and the screw 15. The set melting temperature of the barrel (heating cylinder) 10 was 240 ° C. The screw 15 was rotated by the operation of the screw drive device 18, and the sorted granular material 41 containing the molten additive in the heating cylinder 10 was sent out toward the strand die 11. The melt-sorted granules 41 were filled in the gap 17 between the heating cylinder 10 and the screw 15 from the portion of the heating cylinder 10 to which the hopper 20 was attached to the strand die 11, but in FIG. Only a part of it is shown.

An airtight member 13 for forming the rear end portion 12 into an airtight structure is attached to the rear end portion 12 of the heating cylinder 10 on the screw drive device 18 side, and between the airtight member 13 and the screw 15. A sealing member 14 for making airtight is attached to the airtight member 13. As a result, the airtight state inside the heating cylinder 10 through which the inert gas (for example, nitrogen gas having a purity of about 99.99%) flows can be maintained. When the heating cylinder 10 itself has airtightness, an airtight member or a sealing member is unnecessary. In FIG. 2, the flow of the inert gas is indicated by an arrow.

The extrusion molding machine 100 further includes an inert gas source 30 and a pipe 32 for introducing the inert gas from the inert gas source 30 into the heating cylinder 10. The pipe 32 is attached to a portion of the heating cylinder 10 on the screw drive side side of the portion of the heating cylinder 10 to which the hopper 20 is attached, more specifically, to the airtight member 13. The pipe 32 may be attached to the rear end portion 12 of the heating cylinder 10 on the screw drive device side. A pressure control valve 33 and a pressure sensor 34 are arranged in the middle of the pipe 32. Further, in order to detect the pressure in the hopper 20, a second pressure sensor 36 is attached to the hopper 20. As the pressure control valve 33 and the pressure sensors 34 and 36, those having a well-known method, structure and configuration can be used. The outputs of the pressure sensors 34 and 36 are sent to the pressure control device 31, and the operation of the pressure control valve 33 and the inert gas source 30 is controlled by the output of the pressure control device 31.

The inert gas injection port 35 is a gap through which the inert gas passes, but the raw material polycarbonate resin does not enter. The position and shape of the inert gas injection port 35 are not particularly limited as long as the passage of the inert gas and the outflow of the raw material polycarbonate resin can be prevented, but the opening of the inert gas injection port 35 is punctate. Not linear, more preferably circular.

The inert gas was flowed from the inert gas source 30 to the outside of the system via the pipe 32, the inert gas inlet 35, the heating cylinder 10, and the exhaust portion 22 of the hopper 20. At this time, the hopper 20 is filled with the sorted granules 40, and in the gap 17 between the heating cylinder 10 and the screw 15 from the portion of the heating cylinder 10 to which the hopper 20 is attached to the die 11. The sorted granular material 40 was plasticized.

In this state, the pressure of the portion of the heating cylinder (specifically, the rear end portion 12) through which the inert gas flows is about 2 × 10 ³ Pa (0.02 kgf / cm ² ) higher than the atmospheric pressure, for example. The pressure or pressure change of the inert gas at the rear end portion 12 can be detected by the pressure sensor 34, and the pressure control valve 33 is controlled via the pressure control device 31 based on the detection result of the pressure. The flow rate of the inert gas can be controlled. Further, when the sorted granular material 40 is carried into the hopper 20 by an air flow, the inside of the hopper 20 becomes a negative pressure. As a result, the pressure of the inert gas flowing from the inert gas source 30 to the outside of the system via the pipe 32, the heating cylinder 10, and the hopper 20 changed. The pressure change in the hopper 20 was detected by the second pressure sensor 36, and the pressure of the inert gas at the rear end portion 12 was further detected by the pressure sensor 34. Based on the detection results of these pressures, it was possible to control the pressure control valve 33 and the inert gas source 30 via the pressure control device 31 to control the flow rate of the inert gas. Therefore, even if the pressure inside the hopper 20 changes, the inert gas that flows from the inert gas source 30 to the outside of the system via the pipe 32, the inert gas injection port 35, the heating cylinder 10, and the hopper 20 The flow rate could be maintained almost constant.

Further, the gas generated from the sorted granules 41 plasticized and melted in the gap 17 between the heating cylinder 10 and the screw 15 passes through the hopper 20 together with the inert gas flowing in the heating cylinder 10 and is exhausted from the exhaust unit 22. Was discharged from the system.

In the first embodiment, the oxygen gas concentration in the hopper 20 into which the selected granular material 40 as a raw material was charged and in the strand die 11 was set to 5000 ppm by the nitrogen gas supplied from the inert gas source 30. Further, the oxygen concentration in the hopper 20 into which the sorted granular materials 40 are charged may be lowered by reducing the pressure in the system using the vacuum pump 26 of the extrusion molding machine 110 shown in FIG.

Then, extrusion granulation was performed under the following conditions.
Discharge rate: 500 kg / hr
Set temperature of barrel 10: 240 ° C
Screw rotation speed: 500 rpm

The strands of the polycarbonate resin thus formed were cut while cooling with water to produce pellets. The temperature of the cooling water and the like were adjusted so that the surface temperature of the pellets immediately after cooling was about 85 ° C. The strand at the time of cutting may be water-cooled in the range of, for example, 60 to 120 ° C., or may be air-cooled.

As described above, the pellet produced by using the selected granules of Sample 2 was designated as Example 1. Further, pellets were produced using the selected granules of Samples 3 to 5 and Comparative Sample 1, and used as Examples 2 to 6 and Comparative Example 1 as shown in Table 4 below. The pellets of Examples 2 to 6 and Comparative Example 1 were produced by the same production method as in Example 1 described above, except that the oxygen gas concentration at the time of molding was different.

As is clear from Table 4, it was confirmed that Examples 1 to 6 had a smaller YI value, excellent transparency, and good hue as compared with Comparative Examples. This tendency was particularly remarkable in Example 3 derived from Sample 4 in which the amount of fine powder removed was large. However, even in Examples 4 to 6 in which a slightly larger amount of powder or granular material having a smaller particle size than in Example 3 and Examples 1 and 2 in which a larger amount of powder or granular material was further contained, the solution YI value of the pellet was high. It can be said that the hue was sufficiently improved because it was a sufficiently low level of 1.12 to 1.20 and was about 0.20 or more lower than the solution YI value of the comparative example.

Further, in Example 1, a small amount of Compound A was detected in the decomposed product after alkaline hydrolysis, but in other Examples, none of Compound A was detected. On the other hand, in the comparative example, since it was contained at a concentration of 6.2 wt ppm, it was reconfirmed that the concentration of compound A was related to the hue. Further, in each example, the water content of the pellet was suppressed to 150 ppm by weight or less, and the amount of dissolved oxygen gas was suppressed to 0.004 cm ³ / gram, and good results were obtained.

The resin pellets produced, the oxygen permeability is ^{0cm 3 / (m 2 · 24h} · atm), water vapor transmission rate (40 ℃, 90% RH) in the sealed container is a can 0g / (m ² · 24 hours) I kept it. Then, when the pellets were stored, the air in the container was replaced with nitrogen gas, and the oxygen concentration in the container at the time of storage was set to 1000 ppm.

As described above, by storing or bagging polycarbonate resin pellets having a good hue and a small amount of decomposition products during alkaline hydrolysis and having a low YI value in a container from which oxygen and water have been removed, substantially It was possible to maintain the state of pellets that were uncolored and had high transparency for a long period of time.

From the above results, it is possible to improve the hue and transparency by removing a predetermined amount of components having a small particle size contained in the powder or granular material of the polycarbonate resin to produce pellets, and it is possible to improve the hue and transparency. It was confirmed that a great effect can be obtained as compared with the case of producing pellets in addition to the body.

[Measurement of dissolved oxygen amount]
The amount of oxygen dissolved in the polycarbonate resin pellets was measured as follows. A sample of polycarbonate resin pellets to be measured was taken, the temperature was raised, and the amount of oxygen removed from the sample was measured. Specifically, oxygen contained in 1 g of the sample under the condition of flowing helium as a flow gas using a temperature-rising degassing gas mass spectrometer TPD-Mass (manufactured by Nippon Bell Co., Ltd.) and a detector Q-MASS. The amount was measured. The dissolved oxygen concentration (cm ³ / g) in the resin is calculated from the amount of dissolved oxygen in 1 g of the pellet sample measured in this way.

(II. Manufacture of extruded products from pellets)
Next, an example in which pellets are produced and an extruded product is produced from the pellets will be described. In the following examples, first, the above-mentioned I. From the powder or granular material (particle size distribution 50 to 1200 μm, average particle size 800 μm, solution YI value 1.45) of a polycarbonate resin (S-3000F manufactured by Mitsubishi Engineering Plastics Co., Ltd.) different from the example of pellet production, it is yellow. The solution YI value and the concentration of the compound A were measured for each sample of the selected granules shown in Table 5 below from which the fine powder which is the main cause of the coloring of the material was removed.

The selected granules of Samples 6 to 9 were obtained by removing fine powder from the powder granules of the above resin using sieves having different mesh size. On the other hand, for the sorted granules of the sample 10, fine powder is removed from the powder granules of the resin by using a classification device (manufactured by Freund Turbo Co., Ltd .: turbo screener) capable of automatically sorting the powder granules. Obtained by doing.

The sorted granules of Sample 10 were sorted by a classifier as follows. First, a blade in a cylindrical net made of synthetic fiber with a mesh of 500 mesh provided in the classifier was rotated at high speed. In this state, by sucking air with a suction device (blower means), powder or granular material was supplied together with air from the end opening of the cylindrical net to the inside of the cylinder, and micro-vibration was generated in the net. As a result, most of the powders having a small particle size passed through the side surface of the cylindrical net relatively quickly and fell, whereas the sorted granules that did not pass through the net and the powder having a slightly smaller amount were powders. It moved to the end opposite to the opening where the granules were supplied and fell through the opening.

By using such a classification device, the sorted granules of Sample 10 contained a small amount of powder having a small particle size. That is, while the samples 6 to 9 did not contain fine powder having a particle size equal to or smaller than the size of the opening of each sieve used, the selected particles of the sample 10 contained particles having a particle size of less than 500 μm. , About 3 to 5% by weight was contained based on the total weight of the sorted granules. As described above, by using the classification device, although a small amount of powder or granular material having a small particle size is contained in the selected granules, a large amount of powder or granular material can be quickly sorted by utilizing the centrifugal force. The comparative sample 2 is the unsorted powder or granular material of the above resin.

Comparing the hues of Samples 6 to 10 and Comparative Sample 2 with the concentrations of Compound A, it was confirmed that the sample from which more fine powder was removed had a smaller solution YI value and a better hue. Regarding compound A, undetected was observed in samples 7 to 10 having a particularly good hue, and a detection amount of less than 3 ppm by weight was observed in sample 6 having a good hue, whereas 4.5 in comparative sample 2. It was confirmed that the weight was ppm and the detected amount was large. Thus, it was also confirmed that the concentration of compound A was related to the solution YI value. In Table 5, compound A tends to be more easily detected even in the sample of the sorted granules having a solution YI value of about the same (1.35 to 1.45) as compared with the resin sample in Table 2. .. It is considered that this is due to the fact that the compound A is an index representing the impurities in the polycarbonate resin, but impurities other than the compound A are also present.

Next, pellets were formed using the selected granules of Sample 7 in Table 5 described above. For this pellet formation, the same method as in the above-mentioned Example (I. Pellet production) was used.

As described above, the pellet produced by using the selected granules of Sample 7 was designated as Production Example 1. Further, pellets were produced using the selected granules of Samples 8 to 10 and Comparative Sample 2, and used as Production Examples 2 to 6 and Production Comparative Example 1 as shown in Table 6 below. The pellets of Production Examples 2 to 6 and Production Comparative Example 1 were produced by the same production method as that of Production Example 1 described above, except that the oxygen gas concentration at the time of molding was different.

As is clear from Table 6, it was confirmed that Production Examples 1 to 6 had a smaller YI value, excellent transparency, and good hue as compared with Production Comparative Examples. This tendency was particularly remarkable in Production Examples 2 to 6 derived from Samples 3 to 5 in which the amount of fine powder removed was large. However, even in Production Example 1 in which a large amount of powder or granular material having a smaller particle size was contained as compared with Production Examples 2 to 6, the solution YI value of the pellets was a sufficiently low level of 1.30. In Production Examples 2 to 6, the value is 0.20 or more lower than the solution YI value of Production Comparative Example, and in Production Example 1, it is 0.18 lower than the solution YI value of Production Comparative Example. In the production example, it can be said that the hue is sufficiently improved.

Further, in Production Example 1, a small amount of Compound A was detected in the decomposition product after alkali hydrolysis, but in other Production Examples, none of Compound A was detected. On the other hand, in the production comparative example, since it was contained at a concentration of 6.9 ppm by weight, it was reconfirmed that the concentration of compound A was related to the hue. Further, in each production example, the water content of the pellets was suppressed to 150 ppm by weight or less, and good results were obtained.

Production Example 1-6 was prepared, and the prepared Comparative Example 1 resin pellets, an oxygen permeability ^{0cm 3 / (m 2 · 24h} · atm), water vapor transmission rate (40 ℃, 90% RH) is 0 g / was stored in a sealed container is a (m ² · 24 hours). Then, when the pellets were stored, the air in the container was replaced with nitrogen gas, and the oxygen concentration in the container at the time of storage was set to 1000 ppm.

As described above, by storing or bagging polycarbonate resin pellets having a good hue and a small amount of decomposition products during alkaline hydrolysis and having a low YI value in a container from which oxygen and water have been removed, substantially It was possible to maintain the state of pellets that were uncolored and had high transparency for a long period of time.

The resin pellets of Production Examples 1 to 6 and Comparative Production Example 1 described above were stored in a closed container for 2 weeks, and then opened as follows. First, while the pellets were kept sealed by a closed storage container made of aluminum, the pellets were heated at 80 ° C. for about 4 hours together with the closed container so that the surface temperature of the pellets was 60 ° C. or higher. Immediately after opening the pellets from the closed storage container, in the extrusion molding machine 100 shown in FIG. 2 above, a vacuum pump (not shown) was used to create an atmosphere in which the oxygen concentration in the hopper 20 was 1000 ppm or less. The pellet was allowed to stand. At this time, nitrogen gas was flowed through the upper part of the hopper 20 at a flow rate of 50 liters / minute (20 to 150 liters / minute) and at the rear end of the screw 15 at a flow rate of 20 liters / minute (10 to 50 liters / minute). The oxygen concentration was maintained at the low levels mentioned above.

Then, in order to prevent air bubbles from occurring during extrusion, while maintaining the vacuum degree of the heating cylinder 10 to 1.3 × 10 ⁴ or less, the extruded pellets of each Production Examples and Comparative Production Examples I made it progress. In the extrusion molding of pellets for producing this extrusion-molded product, unlike the extrusion molding of the sorted granular material 40 for pellet formation described above, only the pellets were used without adding any additives.

The polycarbonate resin extruded from the die 11 by extrusion molding of pellets was cut while being air-cooled to produce an extrusion molded product. The shape of the extruded product thus formed was a rectangular shape having a width of 900 mm, a thickness of 2 mm, and a length of 1200 mm, but the shape and size are not particularly limited thereto. For example, the extruded product is in the form of a sheet, a film, or the like. In the second extrusion molding in which the extrusion molded product was produced from the pellets, the pressure (vacuum degree) in the system was different from that of the first extrusion molding in which the pellets were formed from the powder or granular material, except that the pressure (vacuum degree) in the system was different. , Proceeded under the same conditions.

As described above, Table 7 shows the properties of the extruded products produced from the resin pellets of Production Examples 1 to 6 and Comparative Production Example 1, respectively.

As is clear from Table 7, it was confirmed that the extruded products of Examples 7 to 12 had a smaller YI value, excellent transparency, and good hue as compared with Comparative Examples. That is, in each of the extruded products, the solution YI value is larger than that of the pellets (see Table 6) which were the raw materials, but the solution YI values of the extruded products of Examples 7 to 12 are all 2. It was 0.00 or less, which was sufficiently lower than the solution YI value (2.12) of the extruded product of Comparative Example 2. As a result of comparing the properties of the extruded products of Examples 7 to 12 and Comparative Example 2 in this way, by producing the extruded product using pellets having a good hue, the hue of the extruded product is sufficiently improved. It was confirmed that it would be done.

Further, in the extruded product of Example 7, a small amount of Compound A was detected in the decomposed product after alkaline hydrolysis, but in the other Examples, none of Compound A was detected, whereas in Comparative Example. In the extruded product of, it was contained at a concentration of 8.0 wt ppm. From this, it can be said that the concentration of compound A is effective not only as an index for evaluating the hue of extruded products but also as an index for evaluating the hue of extruded products. Further, in each example, the value of the parallel light transmittance at the wavelength of 400 nm is 40% / 300 mm or more and higher than the value of the comparative example, and from this point as well, the extrusion molding of Examples 7 to 12 It was confirmed that the transparency and hue of the product were good.

From the above results, it is possible to improve the hue and transparency by producing an extruded product from pellets in which a predetermined amount of small particle size components contained in the polycarbonate resin powder or granular material is removed, and the additive is powdered. It was confirmed that a large effect can be obtained as compared with the case of producing an extruded product from the conventional pellets added to the granules.

[Measurement of parallel light transmittance]
The parallel light transmittance of the extruded product made of polycarbonate resin was measured as follows. First, an extruded product having a thickness of 300 mm was prepared, and the ratio (% / 300 mm) through which light having a wavelength of 400 nm was transmitted was measured using a C light source. More specifically, based on the standard illuminant standard specified by the CIE (International Commission on Illumination), a C light source with a color temperature of 6740 Kelvin is used to form a 5.2 (a) film and plate of JIS K 7373. According to the transmittance measurement, the measurement was performed using a spectrocolor difference meter ASA-1 manufactured by Nippon Denshoku Industries Co., Ltd.
(III. Manufacture of injection molded products from pellets)

Next, an example in which pellets are produced and an injection-molded product is produced from the pellets will be described. In the same manner as in the above-mentioned Example (I. Production of pellets), the pellet produced using the selected granules of Sample 2 in Table 3 was designated as Production Example 7. Further, pellets were produced using the selected granules of Samples 3 to 5 and Comparative Sample 1, and used as Production Examples 7 to 12 and Production Comparative Example 2 as shown in Table 8 below. The pellets of Production Examples 8 to 12 and Comparative Production Example 2 were produced by the same production method as that of Production Example 7 described above, except that the oxygen gas concentration at the time of molding was different.

As is clear from Table 8, it was confirmed that Production Examples 7 to 12 had a smaller YI value, excellent transparency, and good hue as compared with Production Comparative Examples. This tendency was particularly remarkable in Production Examples 8 to 12 derived from Samples 3 to 5 in which the amount of fine powder removed was large. However, even in Production Example 7 in which a large amount of powder or granular material having a smaller particle size was contained as compared with Production Examples 8 to 12, the solution YI value of the pellets was a sufficiently low level of 1.18, and Production Comparative Example 2 It can be said that the hue was sufficiently improved because it was 0.20 or more lower than the solution YI value of.

Further, in Production Example 7, a small amount of Compound A was detected in the decomposed product after alkaline hydrolysis, but in other Production Examples, none of Compound A was detected (not detected). On the other hand, in the production comparative example, since it was contained at a concentration of 6.2 wt ppm, it was reconfirmed that the concentration of compound A was related to the hue. Further, in each production example, the water content of the pellets was suppressed to 150 ppm by weight or less, and good results were obtained.

Production Example 7-12 was prepared, and the prepared Comparative Example 2 resin pellets, an oxygen permeability ^{0cm 3 / (m 2 · 24h} · atm), water vapor transmission rate (40 ℃, 90% RH) is 0 g / was stored in a sealed container is a (m ² · 24 hours). Then, when the pellets were stored, the air in the container was replaced with nitrogen gas, and the oxygen concentration in the container at the time of storage was set to 1000 ppm.

As described above, by storing or bagging polycarbonate resin pellets having a good hue and a small amount of decomposition products during alkaline hydrolysis and having a low YI value in a container from which oxygen and water have been removed, substantially It was possible to maintain the state of pellets that were uncolored and had high transparency for a long period of time.

The resin pellets of Production Examples 7 to 12 and Comparative Production Example 2 described above were stored in a closed container for 2 weeks, and then opened as follows. First, while the pellets were kept sealed by a closed storage container made of aluminum, the pellets were heated at 80 ° C. for about 4 hours together with the closed container and the like so that the surface temperature of the pellets was 60 ° C. or higher.

An injection molding machine 120 shown in FIG. 4 was used for producing an injection molded product using these pellets. The injection molding machine 120 is attached to a molding cylinder 10'with a resin lead-out portion 11'at the tip, a screw 15 built in the molding cylinder 10', and a molding cylinder 10', and is inside the molding cylinder 10'. It has a hopper 20 for supplying pellets 42 of raw materials, a screw driving device 18 attached to the rear end portion 16 of the screw 15, and the like. The screw 15 arranged in the molding cylinder 10'is an in-line screw that plasticizes and melts the pellet 42 and at the same time functions as a plunger. A heater (not shown) is attached to the outer periphery of the molding cylinder 10', and the pellet 42 existing in the gap 17 between the molding cylinder 10'and the screw 15 can be plasticized and melted.

In the injection molding machine 120, the pellets immediately after being opened from the closed storage container as described above are immediately statically charged in an atmosphere in which the oxygen concentration in the hopper 20 is 950 ppm (1000 ppm or less) using a vacuum pump (not shown). I put it. At this time, nitrogen gas is flowed through the upper part of the hopper 20 at a flow rate of 50 liters / minute (20 to 150 liters / minute) and at the rear end 12 of the screw 15 at a flow rate of 20 liters / minute (10 to 50 liters / minute). , The oxygen concentration was maintained at the low levels described above.

Then, in order to prevent bubbles in the injection molded article is produced, while maintaining the vacuum degree of the molding cylinder 10 in 'to 1.3 × 10 ⁴ or less, the injection of the pellets in each Production Examples and Comparative Production Examples Molding was advanced. In the injection molding of the pellet 42 for producing this injection-molded product, unlike the extrusion molding of the sorted granular material 40 for pellet formation described above, only the pellet 42 was used without adding an additive.

The method of carrying the pellets 42 into the hopper 20 can be any method. For example, a blower (not shown) is arranged downstream of the exhaust portion 22 provided in the hopper 20, and the inside of the hopper 20 is made negative pressure by the operation of the blower, and the piping and the carry-in portion are connected from the storage portion of the raw material pellets 42. The flake-shaped sorted granules 40 may be carried into the hopper 20 through the airflow 21.

The pellet 42 carried into the molding cylinder 10'from the hopper 20 was heated, plasticized, melted, and conveyed by the molding cylinder 10'and the screw 15. The set melting temperature of the barrel (molding cylinder) 10 was 240 ° C. By operating the screw drive device 18, the screw 15 is rotated and pushed forward, and pressure is applied to the molten pellet 43 in the molding cylinder 10'to push the molten pellet 43 from the resin lead-out portion 11'to the mold assembly. Injection was performed toward the molten resin injection unit 54 (see FIG. 5) of 50. The molten pellet 43 flowed into the cavity 53 provided between the first mold portion 51 and the second mold portion 52 via the molten resin injection portion 54 in the mold assembly 50. The molten pellet 43 was filled in the gap 17 between the molding cylinder 10'and the screw 15 from the portion of the molding cylinder 10'to which the hopper 20 was attached to the resin lead-out portion 11'. In, only a part of them is shown.

An airtight member 13 for forming the rear end portion 12 into an airtight structure is attached to the rear end portion 12 of the molding cylinder 10'on the screw drive device 18 side, and the airtight member 13 and the screw 15 are attached to each other. A sealing member 14 for making the space airtight is attached to the airtight member 13. As a result, the airtight state inside the molding cylinder 10'where the inert gas (for example, nitrogen gas having a purity of about 99.99%) flows can be maintained. When the molding cylinder 10'itself has airtightness, an airtight member or a sealing member is unnecessary. In FIG. 4, the flow of the inert gas is indicated by an arrow.

The injection molding machine 120 further includes an inert gas source 30 and a pipe 32 for introducing the inert gas from the inert gas source 30 into the molding cylinder 10'. The pipe 32 is attached to a portion of the molding cylinder 10'on the screw drive device side, more specifically, to the airtight member 13 rather than the portion of the molding cylinder 10'to which the hopper 20 is attached. The pipe 32 may be attached to the rear end portion 12 of the molding cylinder 10'on the screw drive device side. A pressure control valve 33 and a pressure sensor 34 are arranged in the middle of the pipe 32. Further, in order to detect the pressure in the hopper 20, a second pressure sensor 35 is attached to the hopper 20. As the pressure control valve 33 and the pressure sensors 34 and 35, those having a well-known method, structure and configuration can be used. The outputs of the pressure sensors 34 and 35 are sent to the pressure control device 31, and the operation of the pressure control valve 33 and the inert gas source 30 is controlled by the output of the pressure control device 31.

With such a configuration, the inert gas flows from the inert gas source 30 to the outside of the system via the pipe 32, the molding cylinder 10', and the exhaust portion 22 of the hopper 20. That is, the hopper 20 is filled with pellets 42, and the pellets are placed in the gap 17 between the molding cylinder 10'and the screw 15 from the portion of the molding cylinder 10'to which the hopper 20 is attached to the resin lead-out portion 11'. In the plasticized state of 42, the inert gas was flowed from the inert gas source 30 to the outside of the system via the pipe 32, the molding cylinder 10', and the hopper 20.

In this state, the pressure of the molding cylinder portion (specifically, the rear end portion 12) through which the inert gas flows is about 2 × 10 ³ Pa (0.02 kgf / cm ² ) higher than the atmospheric pressure, for example. .. The pressure or pressure change of the inert gas at the rear end portion 12 can be detected by the pressure sensor 34, and the pressure control valve 33 is controlled via the pressure control device 31 based on the detection result of the pressure. The flow rate of the inert gas can be controlled. Further, when the pellet 42 is carried into the hopper 20 by an air flow, the pressure inside the hopper 20 becomes negative. As a result, although the pressure of the inert gas flowing out of the system from the inert gas source 30 via the pipe 32, the molding cylinder 10', and the hopper 20 changes, the pressure change in the hopper 20 is the second. The pressure sensor 35 can detect the pressure of the inert gas, and the pressure sensor 34 can detect the pressure of the inert gas at the rear end portion 12. Based on the detection results of these pressures, the pressure control valve 33 and the inert gas source 30 can be controlled via the pressure control device 31, and the flow rate of the inert gas can be controlled. Therefore, the pressure in the hopper 20 can be controlled. However, the flow rate of the inert gas flowing from the inert gas source 30 to the outside of the system via the pipe 32, the molding cylinder 10', and the hopper 20 can be maintained substantially constant.

Further, the gas generated from the pellet 43 plasticized and melted in the gap 17 between the molding cylinder 10'and the screw 15 is exhausted via the hopper 20 together with the inert gas flowing in the molding cylinder 10'. It was discharged from the unit 22 to the outside of the system.

In Production Example 7, the oxygen gas concentration in the hopper 20 into which the pellet 42 as a raw material was charged and in the molding cylinder 10'was set to 5000 ppm by the nitrogen gas supplied from the inert gas source 30. Further, the oxygen gas concentration may be reduced by using the injection molding machine 130 provided with the exhaust port (vent portion) 19 in the molding cylinder 10'shown in FIG. In the injection molding machine 130, it is easily possible to reduce the pressure in the system by using a vacuum pump (not shown) through the exhaust port (vent portion) 19 or to inject nitrogen while reducing the pressure in the system. is there.

Then, injection molding was performed under the following conditions.
Injection molding machine: Sodick Plustech injection molding machine TR100EH2
Molded product dimensions: width 5 mm x thickness 4 mm length 300 mm
Molding temperature: 320 ° C
Mold temperature: 120 ° C
Molding cycle: 60 seconds

As described above, Table 9 shows the properties of the injection-molded articles of Examples 13 to 18 and Comparative Example 3 produced from the resin pellets of Production Examples 7 to 12 and Comparative Example 2, respectively.

As is clear from Table 9, it was confirmed that the injection-molded products of Examples 1 to 5 had a smaller YI value, excellent transparency, and good hue as compared with Comparative Examples. That is, although the solution YI value of each injection-molded product is larger than that of the pellets (see Table 8) that were the raw materials, the solution YI value of the injection-molded products of Examples 1 to 5 is 2 in each case. It was .00 or less, which was sufficiently lower than the solution YI value (2.28) of the injection-molded article of Comparative Example 1. As a result of comparing the properties of the injection-molded products of Examples 1 to 5 and Comparative Example in this way, by producing the injection-molded product using pellets having a good hue, the hue of the injection-molded product is sufficiently improved. It was confirmed that

Further, in the injection-molded product of Example 1, a small amount of Compound A was detected in the decomposition product after alkali hydrolysis, but in the other Examples, none of Compound A was detected, whereas in Comparative Example. In the injection-molded product of No. 1, it was contained at a concentration of 11.5 wt ppm. From this, it can be said that the concentration of compound A is effective not only as an index for evaluating the hue of injection-molded products but also as an index for evaluating the hue of injection-molded products. Further, in each example, the value of the parallel light transmittance at the wavelength of 400 nm was 40% / 300 mm or more, whereas in the comparative example, it was 36% / 300 mm. From this point as well, it was confirmed that the injection molded products of Examples 1 to 5 had good transparency and hue.

From the above results, it is possible to improve the hue and transparency by producing an injection-molded product from pellets in which a predetermined amount of small-particle size components contained in the powder or granular material of the polycarbonate resin is removed, and the additive is powdered. It was confirmed that a large effect can be obtained as compared with the case of producing an injection-molded product from conventional pellets added to granules.

[Measurement of parallel light transmittance]
The parallel light transmittance of the injection-molded product made of polycarbonate resin was measured as follows. First, an injection-molded product having a thickness of 300 mm was prepared, and the ratio (% / 300 mm) through which light having a wavelength of 400 nm was transmitted was measured using a C light source. More specifically, based on the standard illuminant standard specified by the CIE (International Commission on Illumination), a C light source with a color temperature of 6740 Kelvin is used to form a 5.2 (a) film and plate of JIS K 7373. According to the transmittance measurement, the measurement was performed using a spectrocolor difference meter ASA-1 manufactured by Nippon Denshoku Industries Co., Ltd.
(IV. Manufacture of extruded products from sorted granules)

Next, an example in which an extruded product is produced directly from the sorted granules without producing pellets will be described. An extruded product was produced using the selected granules of Sample 2 described in Table 3 in the same manner as when the pellets were extruded from the sorted granules in the above-mentioned Example (I. Pellet production). For the production of this extruded product, the extrusion molding machine 100 shown in FIG. 2 was used. However, in the extrusion molding machine 100 used in this embodiment for producing the extrusion molded product directly from the sorted granules, a T-die 11 was used instead of the strand die of FIG. Further, although the T-die 11 is used here, another type of die can be used depending on the shape of the extruded product to be manufactured.

Then, unlike the extrusion granulation of pellets from the sorted granules described in (I. Pellet production) described above, extrusion molding was performed under the following conditions.
Discharge rate: 200 kg / hr
Set temperature of barrel 10: 260 ° C
Set temperature of T-die 11: 240 ° C
Screw rotation speed: 70 rpm

The polycarbonate resin extruded from the T-die 11 by this extrusion molding was cut while being air-cooled to produce an extrusion-molded product. The shape of the extruded product thus formed was a rectangular shape having a width of 900 mm, a thickness of 2 mm, and a length of 1200 mm, but the shape and size are not particularly limited thereto. For example, the extruded product is in the form of a sheet, a film, or the like. The polycarbonate resin at the time of cutting may be water-cooled in the range of, for example, 60 to 120 ° C.

As described above, the extruded product produced by using the selected granules of Sample 2 was designated as Example 19. Further, an extruded product was produced using the selected granules of Samples 3 to 5 and Comparative Sample 1, and used as Examples 20 to 24 and Comparative Example 1 as shown in Table 10 below. The extruded products of Examples 20 to 24 and Comparative Example 1 were manufactured by the same manufacturing method as in Example 19 described above, except that the oxygen gas concentration at the time of molding was different.

As is clear from Table 10, it was confirmed that Examples 19 to 24 had a smaller YI value, excellent transparency, and good hue as compared with Comparative Example 4. This tendency was particularly remarkable in Example 21 derived from Sample 4 in which the amount of fine powder removed was large. However, in Examples 22 to 24 in which a slightly larger amount of powder or granular material having a smaller particle size than in Example 21, and in Examples 19 and 20 in which a larger amount of powder or granular material is further contained, the solution YI of the extruded product The value is a sufficiently low level of 1.12 to 1.18, which is 0.20 or more lower than the solution YI value of the comparative example. Further, the extruded products of each example had a parallel light transmittance of 40% / 300 mm or more at a wavelength of 400 nm. From these results, it can be said that the hue and transparency of the extruded products of each example were sufficiently improved.

Further, in Example 19, a small amount of Compound A was detected in the decomposed product after alkaline hydrolysis, but in other Examples, none of Compound A was detected. On the other hand, in Comparative Example 4, since it was contained at a concentration of 6.2 wt ppm, it was reconfirmed that the concentration of Compound A was related to the hue.

From the above results, it is possible to improve the hue and transparency by removing a predetermined amount of components having a small particle size contained in the powder or granular material of the polycarbonate resin to produce an extruded product. It was confirmed that a large effect can be obtained as compared with the case of producing an extruded product in addition to the powder or granular material.

[Measurement of parallel light transmittance]
The parallel light transmittance of the extruded product made of polycarbonate resin was measured in the same manner as in the case of (II. Production of extruded product from pellets) described above.
(V. Manufacture of injection molded products from sorted granules)

Next, an example in which an injection-molded product is produced directly from the sorted granules without producing pellets will be described. Similar to the case where the injection-molded product was produced from the pellets in the above-mentioned Example (III. Production of pellets), the injection-molded product was prepared by using the selected granules of Sample 2 in Table 3 above instead of the pellet 42. Manufactured. The injection molding machine 120 shown in FIG. 4 was used for manufacturing this injection molded product. The composition of the sorted granular material 40 and the additive used here is as follows.
Sorted Granules 40 (Sample 2, Polycarbonate Resin Upiron H-4000F (manufactured by Mitsubishi Engineering Plastics): 99.92 parts by weight ADEKA STAB PEP36 (Bis (2,6-di-tert-butyl-4-ethylphenyl) penta) Eris Ritol Diphosphite Adeka): 0.05 parts by weight Rikemar S100A (glycerin monostearate, made by RIKEN Vitamin): 0.03 parts by weight

In this embodiment, a blower (not shown) is arranged downstream of the exhaust portion 22 provided in the hopper 20, and the inside of the hopper 20 is made a negative pressure by the operation of the blower, and piping and carrying in from the raw material polycarbonate resin storage portion. The flake-shaped sorted granules 40 were carried into the hopper 20 through the section 21. However, as described in the above-mentioned Example (III. Manufacture of pellets), the method of carrying the sorted granules 40 from the resin storage unit to the hopper 20 can be any method.

In this way, the polycarbonate resin filled with the cavity 53 (see FIG. 5) is cooled by injecting from the resin lead-out unit 11 by injection molding using sorted granules instead of the pellets in the example of (III. Manufacture of pellets). Then, an injection-molded product having a shape corresponding to the cavity 53 was manufactured.

As described above, the injection-molded product produced by using the selected granules of Sample 2 was designated as Example 25. Further, injection-molded products were produced using the selected granules of Samples 3 to 5 and Comparative Sample 1, and used as Examples 25 to 30 and Comparative Example 5 as shown in Table 11 below. The injection-molded products of Examples 26 to 30 and Comparative Example 5 were manufactured by the same manufacturing method as in Example 25 described above, except that the oxygen gas concentration at the time of molding was different.

As is clear from Table 11, it was confirmed that Examples 25 to 30 had a smaller YI value, excellent transparency, and good hue as compared with Comparative Example 5. This tendency was particularly remarkable in Examples 26 to 30 derived from Samples 3 to 5 in which the amount of fine powder removed was large. However, even in Example 25 in which a slightly larger amount of powder or granular material having a smaller particle size was contained as compared with Examples 26 to 30, the solution YI value of the injection-molded product was 1.88, which was a sufficiently low level. Yes, it is 0.35 or more lower than the solution YI value of Comparative Example 5. Further, in the injection-molded products of each example, the parallel light transmittance at a wavelength of 400 nm was 40% / 300 mm or more. From these results, it can be said that the hue and transparency were sufficiently improved in the injection-molded products of each example.

Further, in Example 25, a small amount of Compound A was detected in the decomposed product after alkaline hydrolysis, but in other Examples, none of Compound A was detected. On the other hand, in Comparative Example 5, since it was contained at a concentration of 11.5 ppm by weight, it was reconfirmed that the concentration of Compound A was related to the hue.

From the above results, it is possible to improve the hue and transparency by removing a predetermined amount of small particle size components contained in the powder or granular material of the polycarbonate resin to produce an injection-molded product, and it is possible to use conventional additives. It was confirmed that a large effect can be obtained as compared with the case of producing an injection-molded product in addition to the powder or granular material.

[Measurement of dissolved oxygen amount]
The amount of oxygen dissolved in the injection-molded product of the polycarbonate resin was measured as follows. A sample of an injection-molded product of polycarbonate resin to be measured was sampled, the temperature was raised, and the amount of oxygen removed from the sample was measured. Specifically, oxygen contained in 1 g of the sample under the condition of flowing helium as a flow gas using a temperature-rising degassing gas mass spectrometer TPD-Mass (manufactured by Nippon Bell Co., Ltd.) and a detector Q-MASS. The amount was measured. The dissolved oxygen concentration (cm ³ / g) in the resin is calculated from the amount of dissolved oxygen in 1 g of the injection-molded product sample measured in this way.

[Measurement of parallel light transmittance]
The parallel light transmittance of the injection-molded product made of polycarbonate resin was measured in the same manner as in the case of (III. Production of injection-molded product from pellets) described above.

As described above, in the present invention, fine powder is removed from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method, and the granular material is selected to form pellets, thereby coloring yellow (amber). It was possible to obtain pellets made of polycarbonate resin having extremely high transparency with a negligible amount of. Furthermore, by producing an extrusion-molded product or an injection-molded product from the pellets thus formed or the granules from which fine powder has been removed, yellow coloring is negligibly small, and extrusion made of a polycarbonate resin having extremely high transparency is achieved. And injection molded products could also be obtained.

Although the present invention has been described above based on preferred examples, the present invention is not limited to these examples. The structure of the extrusion molding machine described in the examples, the materials used, the granulation conditions, and the like are examples and can be changed as appropriate.

10 Heating cylinder 11 Strand die 12 Rear end of heating cylinder 13 Airtight member 14 Sealing member 15 Screw 16 Screw rear end 17 Void 18 Screw drive device 19 Exhaust port (vent part)
20 Hopper 21 Carry-in part 22 Exhaust part 23 Check valve 24 Inactive gas discharge part 25 Blower 26 Vacuum pump 30 Inactive gas source 31 Pressure control device 32 Piping 33 Pressure control valve 34 Pressure sensor 35 Inactive gas inlet 36 Second Pressure sensor 40 Sorting granules 41 Melting sorting granules 100 Extrusion molding machine (extrusion granulator)
110 Extrusion molding machine (extrusion granulator)
120 injection molding machine 130 injection molding machine

Claims (28)

It is a method of molding a polycarbonate resin to manufacture a molded product.
(A) A particle sorting step of removing fine powder having a particle size of less than 300 μm from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method to obtain a sorted granular material.
(B) Having any of the following steps
(B2) Pellet extrusion step of melting the sorted granules at a temperature of 145 ° C. or higher to form pellets, and extruding the pellets to produce an extruded product:
(B3) Pellet injection step of melting the sorted granules at a temperature of 145 ° C. or higher to form pellets, and injection molding the pellets to produce an injection molded product:
(B4) Extrusion step of extruding the sorted granules to produce an extruded product: or
(B5) An injection step of producing an injection-molded product by injection-molding the sorted granules.
The content of the compound represented by the following formula (A) and the content of the compound represented by the following formula (B) in the decomposed product after alkaline hydrolysis of the obtained selected granules were measured. ,
The selected granules having a content of the compound represented by the following formula (A) of 3 ppm by weight or less and a content of the compound represented by the following formula (B) of 3 wt ppm or less are described in (b2) to the above. Used in step (b5)
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the molded product is 5 ppm by weight or less, and the content of the compound represented by the following formula (B) is 5 weight by weight. Less than ppm
The method for producing a polycarbonate resin molded product, wherein the (a) particle sorting step is a step of obtaining the sorted granules having a particle size of 500 μm or more and a content of 90% by weight or more.
The production method according to claim 1, wherein the solution YI value of the sorted granules is 0.05 or more smaller than the solution YI value of the powder or granular material before obtaining the sorted granules. The production method according to claim 1 or 2, wherein in the (a) granule sorting step, the sorted granules are obtained from the powder or granular materials by using wind power. The production method according to claim 3, wherein the suspended fine powder is removed by using a blowing means to obtain the sorted granules. The production method according to claim 1 or 2, wherein in the (a) granule sorting step, the sorted granules are obtained from the powder or granular material using a sieve. The production method according to claim 5, wherein the fine powder is removed while the sieve is vibrating to obtain the sorted granules. The production method according to any one of claims 1 to 6, wherein the solution YI value of the sorted granules is 1.30 or less. The production method according to any one of claims 1 to 7, wherein the solution YI value of the produced molded product is 2.00 or less. The production method according to any one of claims 1 to 8, wherein the solution YI value of the pellet is 1.40 or less. The production method according to any one of claims 1 to 9, wherein the dissolved oxygen concentration in the pellet is 0.015 cm ³ / g or less, and the water content in the pellet is 300 ppm or less. Prior to the (b2) pellet extrusion step or the (b3) pellet injection step, the pellets are heated in a state of being sealed by a packaging means so that the surface temperature of the pellets becomes 60 ° C. or higher. 10. The production method according to any one of 10. In the (b2) pellet extrusion step or the (b3) pellet injection step, the pellets are extruded or injection molded in an atmosphere where the oxygen concentration is 1000 ppm or less by adding an inert gas and / or reducing the pressure to obtain a molded product. The production method according to any one of claims 1 to 11, wherein the product is produced. In the (b4) extrusion step or the (b5) injection step, the selected granules are extruded or injection-molded in an atmosphere where the oxygen concentration is 10,000 ppm or less by adding an inert gas and / or reducing the pressure to obtain a molded product. The manufacturing method according to claim 1 to 12, wherein the product is manufactured. The production method according to claim 1 to 13, wherein the sorted granules before injection molding are dried to have a water content of 200 ppm or less. The molded product is an extruded product,
(A) A particle sorting step of obtaining a sorted granular material obtained by removing fine powder having a particle size of less than 300 μm from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method.
(B2) A pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets.
It has a pellet extrusion step of extruding the pellet to produce an extruded product.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, and the content of the compound represented by the following formula (B) is 5. The production method according to claim 1, wherein the weight is ppm or less.
The molded product is an injection molded product,
(A) A particle sorting step of obtaining a sorted granular material obtained by removing fine powder having a particle size of less than 300 μm from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method.
(B3) A pellet forming step of melting the sorted granules at a temperature of 145 ° C. or higher to form the pellets.
It has a pellet injection process for producing an injection-molded product by injection-molding the pellets.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection-molded product is 5 ppm by weight or less, and the content of the compound represented by the following formula (B) is 5. The production method according to claim 1, wherein the weight is ppm or less.
The molded product is an extruded product,
(A) A particle sorting step of obtaining a sorted granular material obtained by removing fine powder having a particle size of less than 300 μm from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method.
(B4) It has an extrusion step of extruding the sorted granules to produce an extruded product.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the extruded product is 5 ppm by weight or less, and the content of the compound represented by the following formula (B) is 5. The production method according to claim 1, wherein the weight is ppm or less.
The molded product is an injection molded product,
(A) A particle sorting step of obtaining a sorted granular material obtained by removing fine powder having a particle size of less than 300 μm from the powder or granular material of the polycarbonate resin obtained by the interfacial polymerization method.
(B5) It has an injection step of producing an injection-molded product by injection-molding the sorted granules.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the injection-molded product is 5 ppm by weight or less, and the content of the compound represented by the following formula (B) is 5. The production method according to claim 1, wherein the weight is ppm or less.
It is selected from the powders and granules of the polycarbonate resin obtained by the interfacial polymerization method, fine powders having a particle size of less than 300 μm are removed, and the content of the granules having a particle size of 500 μm or more is 90% by weight or more. It is formed from selected granules having a content of a compound represented by the following formula (A) of 1 wt ppm or less and a content of a compound represented by the following formula (B) of 1 wt ppm or less. It is a molded product
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the obtained molded product is 1 wt ppm or less, and the content of the compound represented by the following formula (B). Is a molded product of polycarbonate resin having a weight of 1 ppm by weight or less.
The molded product
Polycarbonate resin pellets formed from polycarbonate resin powders and granules obtained by an interfacial polymerization method.
The content of the compound represented by the following formula (A) in the decomposition product after alkaline hydrolysis of the pellet is 1 ppm by weight or less, and the content of the compound represented by the following formula (B) is 1 ppm by weight. The molded product as the polycarbonate resin pellet according to claim 19, which is as follows.
The molded product according to claim 20 , wherein the solution YI value of the pellet is 1.40 or less. The molded product according to any one of claims 20 and 21, wherein the dissolved oxygen concentration in the pellet is 0.015 cm ³ / g or less. The molded product according to any one of claims 20 to 22, wherein the water content in the pellet is 300 ppm or less. The molded product according to any one of claims 19 to 23, wherein the solution YI value of the molded product is 2.00 or less. The molded product according to any one of claims 19 to 24, wherein the parallel light transmittance at a wavelength of 400 nm is 40% / 300 mm or more. The molded product
Sorted granules obtained by removing fine powder having a particle size of less than 300 μm from the powder granules of the polycarbonate resin obtained by the interfacial polymerization method are obtained, and the sorted granules are extruded or injection molded to produce or produced. An extrusion-molded product or an injection-molded product produced by extrusion-molding or injection-molding pellets formed by melting the sorted granules.
The content of the compound represented by the following formula (A) in the extrusion-molded product or the decomposition product after alkaline hydrolysis of the injection-molded product is 1 wt ppm or less, and is represented by the following formula (B). The molded article according to claim 19, wherein the content of the compound is 1 ppm by weight or less.
The production method according to claim 1, wherein an ultraviolet absorber is added to the polycarbonate resin in at least one of the steps (b2) to (b5) to produce a molded product containing the ultraviolet absorber together with the polycarbonate resin. .. The molded article according to claim 19, further comprising an ultraviolet absorber.