JP2016113569A - Polycarbonate resin composition for supercritical foam molding and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin composition for supercritical foam molding, which solves the problem of corrosion of a mold cavity surface during supercritical foam molding.SOLUTION: The polycarbonate resin composition for supercritical foam molding contains 0.01-0.5 pt.mass of a stabilizer (B) per 100 pts.mass of a polycarbonate resin (A) which contains 50-100 mass% of a polycarbonate resin (a1) having a structural viscosity index (an N value) of 1.2 or more and a viscosity average molecular weight of 20,000 or more and less than 50,000, and 0-50 mass% of a polycarbonate resin (a2) having a structural viscosity index (an N value) of less than 1.2 and a viscosity average molecular weight of 10,000 or more and less than 25,000, based on 100 mass% of the total of (a1) and (a2).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polycarbonate resin composition and a molded article for supercritical foam molding, and more specifically, a polycarbonate resin composition for supercritical foam molding in which generation of defects such as cavities and swelling due to foam breakage during supercritical foam molding is suppressed. The present invention relates to a molded article and a supercritical foam molded article using the same.

  Polycarbonate resin is a resin excellent in heat resistance, mechanical properties, and electrical properties, and is widely used for automotive materials, electrical / electronic equipment materials, housing materials, materials for manufacturing parts in other industrial fields, etc. In particular, it is suitably used as a part of electric / electronic devices such as computers, notebook computers, various portable terminals, printers, copying machines, and OA / information devices.

  In recent years, these devices have been rapidly reduced in size and weight, and a foam molding method is being adopted in order to reduce the amount of resin used and reduce the weight. As foam molding, there is a method of manufacturing using a chemical foaming agent or a physical foaming agent, but the chemical foaming method is expensive because of the use of the foaming agent, and also due to the decomposition residue of the foaming agent remaining in the foam. There are problems such as discoloration of foam, generation of odor, and contamination of molding machine by chemical foaming agent.

  On the other hand, the gas foaming method using a physical foaming agent is a method of foam molding by melting a resin with a molding machine, supplying a low-boiling organic compound such as butane and kneading, and then releasing it into a low-pressure region. Since the low-boiling organic compound obtained has an affinity for the resin, it is excellent in solubility and can obtain a high-magnification foam. However, these foaming agents are expensive, and low-boiling organic compounds have dangers such as flammability.

  In order to solve such problems, a method has been proposed in which an inert gas such as nitrogen gas or carbon dioxide gas that is clean and inexpensive is used as a blowing agent. However, these inert gases have low solubility because they have a low affinity with the resin, and the resulting foam has a large and uneven cell diameter and low cell density. There's a problem.

Patent Document 1 describes a technique for obtaining a foam having a very fine cell diameter and a large cell density by using a supercritical fluid as a foaming agent and impregnating the supercritical fluid with a resin. The foam molding method using a supercritical fluid as a foaming agent is a microfoam molding technology also called Mucell (registered trademark). A supercritical fluid dissolved in a molten resin under high pressure is subjected to molding and subjected to rapid decompression. This is a molding technique for obtaining a molded product having fine foam cells.
According to this supercritical foam molding, supercritical liquid has excellent solubility close to liquid and excellent diffusibility close to gas, so it has high solubility in resin and also has a high diffusion rate in resin. Therefore, the foaming agent can be impregnated in the resin in a short time.

However, in order to form fine bubbles by supercritical foam molding, it is important to impregnate the resin with a supercritical fluid and rapidly reduce the pressure from high pressure. Thus, it is not easy to perform fine foam molding.
For this reason, in supercritical foam molding, various attempts have been proposed to add various components to the polycarbonate resin to make the foam uniform and eliminate the problems. For example, in Patent Document 2, a surfactant is added to a polycarbonate resin to increase the density of bubble nuclei generated when the pressure is rapidly reduced from high pressure, and the bubbles are refined and densified in subsequent bubble growth. It has been proposed. However, even if such a countermeasure is taken with a normal polycarbonate resin, cavities and swelling due to bubble breakage are likely to occur during supercritical foam molding, and it is not easy to perform stable and fine foam molding.

US Pat. No. 5,158,986 JP 2008-127467 A

  The present invention was devised in view of the above-mentioned problems of the prior art, and is a polycarbonate resin composition for supercritical foam molding in which the occurrence of defects such as cavities and swelling due to bubble breakage in supercritical foam molding of polycarbonate resin is suppressed. The purpose is to provide goods.

As a result of intensive studies in order to achieve the above-mentioned problems, the present inventor used a polycarbonate resin having a high molecular weight and a specific molecular weight as a polycarbonate resin and a polycarbonate resin having a linear and low molecular weight, and a stabilizer. It discovered that the compounded polycarbonate resin composition solved the said subject, and came to complete this invention.
The present invention provides the following supercritical foam molding polycarbonate resin composition and molded article.

[1] A polycarbonate resin (a1) having a structural viscosity index (N value) of 1.2 or more and a viscosity average molecular weight of 20,000 or more and less than 50,000, and a structural viscosity index (N value) of 1.2. The polycarbonate resin (a2) having a viscosity average molecular weight of 10,000 or more and less than 25,000 is less than 50% by mass, and (a1) is 50 to 100% by mass based on the total of 100% by mass of (a1) and (a2). A polycarbonate resin composition for supercritical foam molding comprising 0.01 to 0.5 parts by mass of a stabilizer (B) with respect to 100 parts by mass of a polycarbonate resin (A) containing 0 to 50% by mass of [2] Further, the polycarbonate oligomer (C) having a viscosity average molecular weight of 1,000 or more and less than 10,000 is contained in an amount of 5 to 60 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). The supercritical foam molding polycarbonate resin composition according to [1].
[3] The supercritical foam according to [1] or [2], wherein the viscosity average molecular weight of the polycarbonate resin (a1) is larger than the viscosity average molecular weight of the polycarbonate resin (a2), and the difference is 5,000 or more. Polycarbonate resin composition for molding.
[4] The polycarbonate resin composition for supercritical foam molding according to any one of the above [1] to [3], wherein the difference in viscosity average molecular weight between the polycarbonate resin (a1) and the polycarbonate oligomer (C) is 10,000 or more. .
[5] The supercritical foam according to any one of [1] to [4], further comprising 0.1 to 5 parts by mass of the fluoropolymer (D) with respect to 100 parts by mass of the polycarbonate resin (A). Polycarbonate resin composition for molding.
[6] The polycarbonate resin composition for supercritical foam molding according to any one of the above [1] to [5], wherein the gas used for supercritical foaming is nitrogen gas or carbon dioxide gas.
[7] A molded article formed by supercritical foam molding using the polycarbonate resin composition for supercritical foam molding according to any one of [1] to [6].

  The polycarbonate resin composition for supercritical foam molding of the present invention suppresses the occurrence of defects such as cavities and blisters due to bubble breakage during supercritical foam molding, eliminates the problem of molding defects, and is stable, uniform and fine. A critical foam molded article can be obtained. Although the mechanism for producing such an effect has not been sufficiently elucidated, a branched polycarbonate resin having a structural viscosity index (N value) of 1.2 or more and a linear low resin having an N value of less than 1.2. By using a polycarbonate resin with a molecular weight, the rubber-like region is expanded and the extensional viscosity is increased, and by adding a stabilizer, cell breakage formed during supercritical foam molding is sufficiently suppressed, and voids due to bubble breakage It can be inferred that it suppresses the occurrence of defects such as swelling and blistering.

It is a graph which shows the result of the complex elastic modulus of the polycarbonate resin composition obtained by the Example and the comparative example. It is a graph which shows the result of the extensional viscosity measurement of the polycarbonate resin composition obtained by the Example and the comparative example.

Hereinafter, although an embodiment, an example thing, etc. are shown and explained in detail about the present invention, the present invention is limited to an embodiment, an example, etc. shown below and is not interpreted.
In the present specification, unless otherwise specified, “to” is used in a sense that includes numerical values described before and after it as a lower limit value and an upper limit value.

  The polycarbonate resin composition for supercritical foam molding of the present invention has a structural viscosity index (N value) of 1.2 or more and a viscosity average molecular weight of 20,000 or more and less than 50,000, and a polycarbonate resin (a1), A polycarbonate resin (a2) having a structural viscosity index (N value) of less than 1.2 and a viscosity average molecular weight of 10,000 or more and less than 25,000 is calculated based on the total of 100% by mass of (a1) and (a2). ) Is contained in an amount of 0.01 to 0.5 parts by weight of the stabilizer (B) with respect to 100 parts by weight of the polycarbonate resin (A) containing 0 to 50% by weight of (a2). And

[Polycarbonate resin (A)]
The polycarbonate resin (A) which is the component (A) of the present invention has a structural viscosity index (N value) of 1.2 or more and a viscosity average molecular weight of 20,000 or more and less than 50,000. And a polycarbonate resin containing a polycarbonate resin (a2) having a structural viscosity index (N value) of less than 1.2 and a viscosity average molecular weight of 10,000 or more and less than 25,000.

[Polycarbonate resin (a1)]
The polycarbonate resin (a1) is a polycarbonate resin having a structural viscosity index (hereinafter also referred to as N value or N) of 1.2 or more.
The structural viscosity index N is an index for evaluating the flow characteristics of a melt as described in detail in the document “Rheology for chemists” (Chemical Doujin, 1982, pp. 15-16). . Usually, the melting characteristics of polycarbonate resin can be expressed by the formula: γ = a · σ ^N. In the above formula, γ: shear rate, a: constant, σ: stress, N: structural viscosity index.

  In the above formula, when N = 1, Newtonian fluidity is shown, and the non-Newtonian fluidity increases as the value of N increases. That is, the structural viscosity index N is an indicator of the flow characteristics of the melt, and the polycarbonate resin having a large structural viscosity index N has a high melt viscosity in a low shear region.

The polycarbonate resin (a1) preferably has a structural viscosity index N of 1.3 or more, more preferably 1.35 or more, more preferably 1.38 or more, and 2.5 or less. Preferably, it is 2.0 or less, more preferably 1.8 or less, and particularly preferably 1.7 or less, and particularly preferably 1.65 or less.
Such a high structural viscosity index N means that the polycarbonate resin has a branched structure.

The structural viscosity index N can also be expressed by Log η _a = [(1-N) / N] × Log γ + C, which is derived from the above equation, as described in, for example, JP-A-2005-232442. Is possible. In the above formula, N: structural viscosity index, γ: shear rate, C: constant, η _a : apparent viscosity. As can be seen from this equation, the N value can also be evaluated from γ and ηa in _a low shear region in which the viscosity behavior is greatly different. For example, the N value can be determined from η _a at γ = 12.16 sec ⁻¹ and γ = 24.32 sec ⁻¹ .

  A polycarbonate resin having a structural viscosity index N of 1.2 or more is obtained by, for example, a dihydroxy compound and a dihydroxy compound by a melting method (transesterification method) as described in JP-A-8-259687 and JP-A-8-245782. When the carbonic acid diester is reacted, a polycarbonate resin having a high structural viscosity index and excellent hydrolysis stability can be obtained without adding a branching agent by selecting the catalyst conditions or production conditions.

In addition, a polycarbonate resin having a structural viscosity index N of 1.2 or more can be produced by a method using a branching agent when produced by a phosgene method or a melting method (a transesterification method) according to a conventional method.
Specific examples of the branching agent include phloroglucin, 4,6-dimethyl-2,4,6-tris (4-hydroxyphenyl) heptene-2, 4,6-dimethyl-2,4,6-tris (4-hydroxy). Phenyl) heptane, 2,6-dimethyl-2,4,6-tris (4-hydroxyphenylheptene-3,1,3,5-tris (4-hydroxyphenyl) ethane and the like, and 3,3-bis (4-hydroxyaryl) oxindole (= isatin bisphenol), 5-chlorisatin bisphenol, 5,7-dichloroisatin bisphenol, 5-bromoisatin bisphenol and the like.
The amount used is preferably in the range of 0.01 to 10 mol%, particularly preferably in the range of 0.1 to 3 mol%, based on the dihydroxy compound.

  The molecular weight of the polycarbonate resin (a1) is a viscosity average molecular weight (Mv) described later, and is 20,000 or more and less than 50,000, preferably 22,000 or more, more preferably 23,000 or more, especially 24,000 or more. In particular, it is preferably 25,000 or more, preferably 45,000 or less, more preferably 40,000 or less, especially 35,000 or less, and particularly preferably 32,000 or less. When the viscosity average molecular weight is within this range, the resulting resin composition has good moldability in supercritical foam molding, and a molded product having high mechanical strength is easily obtained.

[Polycarbonate resin (a2)]
The polycarbonate resin (a2) is a polycarbonate resin having a structural viscosity index (N value) of less than 1.2 and a viscosity average molecular weight of 10,000 or more and less than 25,000.
The viscosity average molecular weight of the polycarbonate resin (a2) is preferably 12,000 or more, more preferably 13,000 or more, especially 14,000 or more, particularly 15,000 or more, and preferably 22,000. Or less, more preferably 20,000 or less, and particularly preferably 18,000 or less.

  Here, the viscosity average molecular weight of the polycarbonate resin (a1) is preferably larger than the viscosity average molecular weight of the polycarbonate resin (a2), and the difference between the viscosity average molecular weights of the polycarbonate resin (a1) and the polycarbonate resin (a2) is 5,000 or more, more preferably 6,000 or more, further 7,000 or more, especially 8,000 or more, especially 9,000 or more, and particularly preferably 10,000 or more. This difference in viscosity average molecular weight is preferable because the fluidity of the resin composition can be increased and a large molded product can be formed without difficulty.

  The structural viscosity index (N value) of the polycarbonate resin (a2) is preferably 1.15 or less, more preferably 1.10 or less, still more preferably 1.05 or less, and usually 1.0 or more. An N value of less than 1.2 means that the polycarbonate resin has a small degree of branching and is linear. Such a polycarbonate resin (a2) is preferably produced by an interfacial polymerization method.

  In the polycarbonate resin composition of the present invention, the polycarbonate resin (a2) having such N value and Mv is in the range of 0 to 50% by mass based on the total of 100% by mass of the polycarbonate resins (a1) and (a2). contains. The content of the polycarbonate resin (a2) is preferably 5% by mass or more, more preferably 8% by mass or more, further preferably 10% by mass or more, preferably 45% by mass or less, and more preferably 40% by mass. It is not more than mass%, more preferably not more than 37 mass%, particularly not more than 35 mass%.

In the present invention, the viscosity average molecular weights of the polycarbonate resins (a1) and (a2) are determined by measuring the viscosity of the methylene chloride solution of the polycarbonate resin at 20 ° C. using an Ubbelohde viscometer and calculating the intrinsic viscosity ([η]). The viscosity average molecular weight (Mv) calculated from the following Schnell viscosity formula.
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83

  There is no restriction | limiting in the kind of polycarbonate resin (a1) and (a2), Although aromatic polycarbonate resin, aliphatic polycarbonate resin, and aromatic-aliphatic polycarbonate resin are mentioned, Preferably, it is aromatic polycarbonate resin, and is concrete. For this, a thermoplastic aromatic polycarbonate polymer or copolymer obtained by reacting an aromatic dihydroxy compound with phosgene or a diester of carbonic acid is preferably used.

Among monomers used as raw materials for aromatic polycarbonate resins, examples of aromatic dihydroxy compounds include:
Dihydroxybenzenes such as 1,2-dihydroxybenzene, 1,3-dihydroxybenzene (ie, resorcinol), 1,4-dihydroxybenzene;
Dihydroxybiphenyls such as 2,5-dihydroxybiphenyl, 2,2′-dihydroxybiphenyl, 4,4′-dihydroxybiphenyl;
2,2′-dihydroxy-1,1′-binaphthyl, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, , 7-dihydroxynaphthalene, dihydroxynaphthalene such as 2,7-dihydroxynaphthalene;

2,2′-dihydroxydiphenyl ether, 3,3′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether, 1,4-bis (3-hydroxyphenoxy) Dihydroxy diaryl ethers such as benzene and 1,3-bis (4-hydroxyphenoxy) benzene;

2,2-bis (4-hydroxyphenyl) propane (ie, bisphenol A),
1,1-bis (4-hydroxyphenyl) propane,
2,2-bis (3-methyl-4-hydroxyphenyl) propane,
2,2-bis (3-methoxy-4-hydroxyphenyl) propane,
2- (4-hydroxyphenyl) -2- (3-methoxy-4-hydroxyphenyl) propane,
1,1-bis (3-tert-butyl-4-hydroxyphenyl) propane,
2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane,
2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane,
2- (4-hydroxyphenyl) -2- (3-cyclohexyl-4-hydroxyphenyl) propane,
α, α′-bis (4-hydroxyphenyl) -1,4-diisopropylbenzene,
1,3-bis [2- (4-hydroxyphenyl) -2-propyl] benzene,
Bis (4-hydroxyphenyl) methane,
Bis (4-hydroxyphenyl) cyclohexylmethane,
Bis (4-hydroxyphenyl) phenylmethane,
Bis (4-hydroxyphenyl) (4-propenylphenyl) methane,
Bis (4-hydroxyphenyl) diphenylmethane,
Bis (4-hydroxyphenyl) naphthylmethane,
1,1-bis (4-hydroxyphenyl) ethane,
1,1-bis (4-hydroxyphenyl) -1-phenylethane,
1,1-bis (4-hydroxyphenyl) -1-naphthylethane,
1,1-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) pentane,
1,1-bis (4-hydroxyphenyl) hexane,
2,2-bis (4-hydroxyphenyl) hexane,
1,1-bis (4-hydroxyphenyl) octane,
2,2-bis (4-hydroxyphenyl) octane,
1,1-bis (4-hydroxyphenyl) hexane,
4,4-bis (4-hydroxyphenyl) heptane,
2,2-bis (4-hydroxyphenyl) nonane,
1,1-bis (4-hydroxyphenyl) decane,
1,1-bis (4-hydroxyphenyl) dodecane,
Bis (hydroxyaryl) alkanes such as;

1,1-bis (4-hydroxyphenyl) cyclopentane,
1,1-bis (4-hydroxyphenyl) cyclohexane,
1,1-bis (4-hydroxyphenyl) -3,3-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,4-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,5-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane,
1,1-bis (4-hydroxy-3,5-dimethylphenyl) -3,3,5-trimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3-propyl-5-methylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3-tert-butyl-cyclohexane,
1,1-bis (4-hydroxyphenyl) -4-tert-butyl-cyclohexane,
1,1-bis (4-hydroxyphenyl) -3-phenylcyclohexane,
1,1-bis (4-hydroxyphenyl) -4-phenylcyclohexane,
Bis (hydroxyaryl) cycloalkanes such as;

Cardostructure-containing bisphenols such as 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene;

Dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide;

Dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide;

Dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone;

Among these, bis (hydroxyaryl) alkanes are preferable, and bis (4-hydroxyphenyl) alkanes are preferable, and 2,2-bis (4-hydroxyphenyl) propane (ie, from the viewpoint of impact resistance and heat resistance). Bisphenol A) is preferred.
In addition, 1 type may be used for an aromatic dihydroxy compound and it may use 2 or more types together by arbitrary combinations and a ratio.

  Among the monomers used as the raw material for the aromatic polycarbonate resin, carbonyl halides, carbonate esters and the like are used as examples of the carbonate precursor. In addition, 1 type may be used for a carbonate precursor and it may use 2 or more types together by arbitrary combinations and a ratio.

  Specific examples of carbonyl halides include phosgene; haloformates such as bischloroformate of dihydroxy compounds and monochloroformate of dihydroxy compounds.

  Specific examples of the carbonate ester include diaryl carbonates such as diphenyl carbonate and ditolyl carbonate; dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; biscarbonate bodies of dihydroxy compounds, monocarbonate bodies of dihydroxy compounds, and cyclic carbonates. And carbonate bodies of dihydroxy compounds such as

  The polycarbonate resins (a1) and (a2) may be a homopolymer composed of one type of repeating unit or a copolymer having two or more types of repeating units. At this time, the copolymer can be selected from various copolymerization forms such as a random copolymer and a block copolymer.

-Manufacturing method of polycarbonate resin (a1), (a2) The manufacturing method of polycarbonate resin (a1), (a2) is not limited, for example, interfacial polymerization method, melt transesterification method, pyridine method, cyclic carbonate Examples thereof include a ring-opening polymerization method of a compound and a solid phase transesterification method of a prepolymer.
Hereinafter, a particularly preferable one of these methods will be specifically described.

.. Interfacial polymerization method First, the case where a polycarbonate resin is produced by the interfacial polymerization method will be described. In the interfacial polymerization method, a dihydroxy compound and a carbonate precursor (preferably phosgene) are reacted in the presence of an organic solvent inert to the reaction and an aqueous alkaline solution, usually at a pH of 9 or higher. Polycarbonate resin is obtained by interfacial polymerization in the presence. In the reaction system, a molecular weight adjusting agent (terminal terminator) may be present as necessary, or an antioxidant may be present to prevent the oxidation of the dihydroxy compound.

  The dihydroxy compound and the carbonate precursor are as described above. Of the carbonate precursors, phosgene is preferably used, and a method using phosgene is particularly called a phosgene method.

  Examples of the organic solvent inert to the reaction include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, monochlorobenzene and dichlorobenzene; aromatic hydrocarbons such as benzene, toluene and xylene; It is done. In addition, 1 type may be used for an organic solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the alkali compound contained in the alkaline aqueous solution include alkali metal compounds and alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium hydrogen carbonate, among which sodium hydroxide and water Potassium oxide is preferred. In addition, an alkali compound may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Although there is no restriction | limiting in the density | concentration of the alkali compound in alkaline aqueous solution, Usually, in order to control pH in the alkaline aqueous solution of reaction to 10-12, it is used at 5-10 mass%. For example, when phosgene is blown, the molar ratio of the bisphenol compound and the alkali compound is usually 1: 1.9 or more in order to control the pH of the aqueous phase to be 10 to 12, preferably 10 to 11. Among these, it is preferable that the ratio is 1: 2.0 or more, usually 1: 3.2 or less, and more preferably 1: 2.5 or less.

  Examples of the polymerization catalyst include aliphatic tertiary amines such as trimethylamine, triethylamine, tributylamine, tripropylamine, and trihexylamine; alicyclic rings such as N, N′-dimethylcyclohexylamine and N, N′-diethylcyclohexylamine. Formula tertiary amines; aromatic tertiary amines such as N, N′-dimethylaniline and N, N′-diethylaniline; quaternary ammonium salts such as trimethylbenzylammonium chloride, tetramethylammonium chloride, triethylbenzylammonium chloride, etc. Pyridine; guanidine salt; and the like. In addition, 1 type may be used for a polymerization catalyst and it may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the molecular weight regulator include aromatic phenols having a monohydric phenolic hydroxyl group; aliphatic alcohols such as methanol and butanol; mercaptans; phthalimides and the like. Of these, aromatic phenols are preferred. Specific examples of such aromatic phenols include alkyl groups such as m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, p-tert-butylphenol, and p-long chain alkyl-substituted phenol. Examples thereof include substituted phenols; vinyl group-containing phenols such as isopropanyl phenol; epoxy group-containing phenols; carboxyl group-containing phenols such as o-oxinebenzoic acid and 2-methyl-6-hydroxyphenylacetic acid; In addition, a molecular weight regulator may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The usage-amount of a molecular weight regulator is 0.5 mol or more normally with respect to 100 mol of dihydroxy compounds, Preferably it is 1 mol or more, and is 50 mol or less normally, Preferably it is 30 mol or less. By making the usage-amount of a molecular weight modifier into this range, the thermal stability and hydrolysis resistance of a polycarbonate resin composition can be improved.

In the reaction, the order of mixing the reaction substrate, reaction medium, catalyst, additive and the like is arbitrary as long as a desired polycarbonate resin is obtained, and an appropriate order may be arbitrarily set. For example, when phosgene is used as the carbonate precursor, the molecular weight regulator can be mixed at any time as long as it is between the reaction (phosgenation) of the dihydroxy compound and phosgene and the start of the polymerization reaction.
In addition, reaction temperature is 0-40 degreeC normally, and reaction time is normally several minutes (for example, 10 minutes)-several hours (for example, 6 hours).

-Melt transesterification method Next, the case where a polycarbonate resin is manufactured by the melt transesterification method is demonstrated.

  As described above, the polycarbonate resin (a1) having a structural viscosity index N of 1.2 or more is preferably produced by a melting method (a transesterification method), and the conditions for the catalyst when the aromatic dihydroxy compound and the carbonic acid diester are reacted. Alternatively, by selecting the production conditions, a polycarbonate resin having a high structural viscosity index and excellent hydrolytic stability can be obtained without adding a branching agent.

In the melt transesterification method, for example, a transesterification reaction between a carbonic acid diester and a dihydroxy compound is performed.
The dihydroxy compound is as described above.
On the other hand, examples of the carbonic acid diester include dialkyl carbonate compounds such as dimethyl carbonate, diethyl carbonate, and di-tert-butyl carbonate; diphenyl carbonate; substituted diphenyl carbonate such as ditolyl carbonate, and the like. Among these, diphenyl carbonate and substituted diphenyl carbonate are preferable, and diphenyl carbonate is more preferable. In addition, 1 type may be used for carbonic acid diester, and it may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the dihydroxy compound and the carbonic acid diester is arbitrary as long as the desired polycarbonate resin can be obtained, but it is preferable to use an equimolar amount or more of the carbonic acid diester with respect to 1 mol of the dihydroxy compound. Is more preferable. The upper limit is usually 1.30 mol or less. By setting it as such a range, the amount of terminal hydroxyl groups can be adjusted to a suitable range.

  In the polycarbonate resin, the amount of terminal hydroxyl groups tends to have a great influence on thermal stability, hydrolysis stability, color tone and the like. For this reason, you may adjust the amount of terminal hydroxyl groups as needed by a well-known arbitrary method. In the transesterification reaction, a polycarbonate resin in which the amount of terminal hydroxyl groups is adjusted can be usually obtained by adjusting the mixing ratio of the carbonic diester and the aromatic dihydroxy compound; the degree of vacuum during the transesterification reaction, and the like. In addition, the molecular weight of the polycarbonate resin usually obtained can also be adjusted by this operation.

When adjusting the amount of terminal hydroxyl groups by adjusting the mixing ratio of the carbonic acid diester and the dihydroxy compound, the mixing ratio is as described above.
Further, as a more aggressive adjustment method, there may be mentioned a method in which a terminal terminator is mixed separately during the reaction. Examples of the terminal terminator at this time include monohydric phenols, monovalent carboxylic acids, carbonic acid diesters, and the like. In addition, 1 type may be used for a terminal terminator and it may use 2 or more types together by arbitrary combinations and a ratio.

  When producing a polycarbonate resin by the melt transesterification method, a transesterification catalyst is usually used. Any transesterification catalyst can be used. Among them, it is preferable to use, for example, an alkali metal compound and / or an alkaline earth metal compound. In addition, auxiliary compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds may be used in combination. In addition, 1 type may be used for a transesterification catalyst and it may use 2 or more types together by arbitrary combinations and a ratio.

  In the melt transesterification method, the reaction temperature is usually 100 to 320 ° C. The pressure during the reaction is usually a reduced pressure condition of 2 mmHg or less. As a specific operation, a melt polycondensation reaction may be performed under the above-mentioned conditions while removing a by-product such as an aromatic hydroxy compound.

  The melt polycondensation reaction can be performed by either a batch method or a continuous method. When performing by a batch type, the order which mixes a reaction substrate, a reaction medium, a catalyst, an additive, etc. is arbitrary as long as a desired aromatic polycarbonate resin is obtained, What is necessary is just to set an appropriate order arbitrarily. However, considering the stability of the polycarbonate resin and the polycarbonate resin composition, the melt polycondensation reaction is preferably carried out continuously.

  In the melt transesterification method, a catalyst deactivator may be used as necessary. As the catalyst deactivator, any compound that neutralizes the transesterification catalyst can be used. Examples thereof include sulfur-containing acidic compounds and derivatives thereof. In addition, a catalyst deactivator may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The amount of the catalyst deactivator used is usually 0.5 equivalents or more, preferably 1 equivalent or more, and usually 10 equivalents or less, relative to the alkali metal or alkaline earth metal contained in the transesterification catalyst. Preferably it is 5 equivalents or less. Furthermore, it is 1 ppm or more normally with respect to aromatic polycarbonate resin, and is 100 ppm or less normally, Preferably it is 20 ppm or less.

[Stabilizer (B)]
The polycarbonate resin composition for supercritical foam molding of the present invention contains 0.01 to 0.5 parts by mass of the stabilizer (B) with respect to 100 parts by mass of the polycarbonate resin (A).

  The stabilizer (B) is preferably a phosphorus stabilizer or a phenol stabilizer.

  Any known phosphorous stabilizer can be used. Specific examples include phosphorus oxo acids such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphoric acid; acidic pyrophosphate metal salts such as acidic sodium pyrophosphate, acidic potassium pyrophosphate, and acidic calcium pyrophosphate; phosphoric acid Group 1 or Group 2B metal phosphates such as potassium, sodium phosphate, cesium phosphate and zinc phosphate; organic phosphate compounds, organic phosphite compounds, organic phosphonite compounds, etc. Particularly preferred.

Organic phosphite compounds include triphenyl phosphite, tris (monononylphenyl) phosphite, tris (monononyl / dinonyl phenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, monooctyl Diphenyl phosphite, dioctyl monophenyl phosphite, monodecyl diphenyl phosphite, didecyl monophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, 2,2-methylenebis (4,6-di- tert-butylphenyl) octyl phosphite and the like.
Specific examples of such organic phosphite compounds include, for example, “ADEKA STAB 1178”, “ADEKA STAB 2112”, “ADEKA STAB HP-10” manufactured by ADEKA, “JP-351” manufactured by Johoku Chemical Industry Co., Ltd., “ JP-360 ”,“ JP-3CP ”,“ Irgaphos 168 ”manufactured by BASF, and the like.
In addition, 1 type may contain phosphorus stabilizer and 2 or more types may contain it by arbitrary combinations and a ratio.

  The content of the phosphorus-based stabilizer is 0.01 parts by mass or more, preferably 0.02 parts by mass or more, more preferably 0.03 parts by mass or more with respect to 100 parts by mass of the polycarbonate resin (A). Moreover, it is 0.5 mass part or less, Preferably it is 0.4 mass part or less, More preferably, it is 0.3 mass part or less. When the content of the phosphorus stabilizer is in the above range, molecular weight reduction and crosslinking during molding are suppressed, so that the molecular weight distribution can be made uniform and the foamed state, that is, the cell shape can be stabilized.

  As a phenol type stabilizer, a hindered phenol type antioxidant is mentioned, for example. Specific examples thereof include 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-hydroxyphenyl) propionamide], 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] ] Methyl] phosphoate, 3,3 ', 3 ", 5,5', 5" -hexa-tert-butyl-a, a ', a -(Mesitylene-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, 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6 Di -tert- pentylphenyl acrylate.

Among them, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate preferable. Specific examples of such a phenolic antioxidant include “Irganox 1010”, “Irganox 1076” manufactured by BASF, “Adekastab AO-50”, “Adekastab AO-60” manufactured by ADEKA, and the like. Is mentioned.
In addition, 1 type may contain the phenol type stabilizer, and 2 or more types may contain it by arbitrary combinations and a ratio.

  Content of a phenol type stabilizer is 0.01 mass part or more with respect to 100 mass parts of polycarbonate resin (A), Preferably it is 0.02 mass part or more, and is 0.5 mass part or less. It is preferably 0.4 parts by mass or less. When the content of the phenol-based stabilizer is less than the lower limit of the above range, when the content of the phenol-based stabilizer is within the above range, molecular weight reduction and crosslinking during molding are suppressed, so the molecular weight distribution becomes uniform, The foamed state, that is, the cell shape can be stabilized.

[Polycarbonate oligomer (C)]
The polycarbonate resin composition for supercritical foam molding of the present invention preferably contains a polycarbonate oligomer (C).
The polycarbonate oligomer (C) preferably has a viscosity average molecular weight of 1,000 or more and less than 10,000, and more preferably 2,000 to 8,000. When the molecular weight is less than 1,000, the mechanical strength decreases, and when the molecular weight is 10,000 or more, the effect of expanding the rubbery region due to the decrease in Tg is small.

  The difference in viscosity average molecular weight between the polycarbonate resin (a1) and the polycarbonate oligomer (C) is preferably 10,000 or more, more preferably 12,000 or more, further 14,000 or more, and especially 14,000 or more. In particular, it is preferably 16,000 or more, particularly 18,000 or more. The difference in viscosity average molecular weight is preferable because the ratio of the branched polycarbonate increases when compared with the same fluidity, and the effect of expanding the rubbery region and the effect of increasing the extension viscosity described later is increased.

Polycarbonate oligomer (C) is 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3). , 5-dibromophenyl) propane by reaction of an aromatic dihydric phenolic compound typically exemplified by phosgene and a transesterification reaction of aromatic dihydric phenol with diphenyl carbonate or the like. What is obtained is preferable, and the aromatic dihydric phenol compound may be used alone or in combination.
In the interfacial polymerization method using phosgene, the polymerization degree of the polycarbonate oligomer may be adjusted by adding phenol and / or alkyl-substituted phenol to the polymerization system and end-capping.

  The content of the polycarbonate oligomer (C) is preferably 5 to 60 parts by mass, more preferably 8 parts by mass or more, further preferably 10 parts by mass or more, relative to 100 parts by mass of the polycarbonate resin (A). Preferably it is 55 mass parts or less, More preferably, it is 50 mass parts or less.

[Fluoropolymer (D)]
The polycarbonate resin composition of the present invention preferably contains a fluoropolymer (D).
Examples of the fluoropolymer (D) include a fluoroolefin resin. The fluoroolefin resin is usually a polymer or copolymer containing a fluoroethylene structure. Specific examples include difluoroethylene resin, tetrafluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, and the like. Of these, tetrafluoroethylene resin and the like are preferable. The fluoroethylene resin may be either a fluoroethylene resin that does not have fibril-forming ability or a fluoroethylene resin that has fibril-forming ability, and preferably a fluoroethylene resin that has fibril-forming ability.

  Examples of the fluoroethylene resin having no fibril-forming ability include “Lublon L5” and “Lublon L7” manufactured by Daikin Industries, Ltd. Examples of the fluoroethylene resin having a fibril-forming ability include, for example, Mitsui and DuPont. Examples thereof include “Teflon (registered trademark) 6J”, “Teflon (registered trademark) 640J” manufactured by Fluorochemical Co., Ltd., “Polyfluorocarbon F201L”, “Polyfluorocarbon F103”, “Polyfluorocarbon FA500B”, and “Polyfluorocarbon FA500H” manufactured by Daikin Industries, Ltd. Further, examples of commercially available aqueous dispersions of fluoroethylene resin include “Teflon (registered trademark) 31-JR” manufactured by Mitsui DuPont Fluorochemical Co., Ltd. and “Fullon D-210C” manufactured by Daikin Industries, Ltd. Furthermore, a fluoroethylene polymer having a multilayer structure obtained by polymerizing vinyl monomers can also be used. Examples of such a fluoroethylene polymer include polystyrene-fluoroethylene composites, polystyrene-acrylonitrile-fluoroethylene. Examples include composites, polymethyl methacrylate-fluoroethylene composites, polybutyl methacrylate-fluoroethylene composites, etc. Specific examples include “Metablene A-3800” manufactured by Mitsubishi Rayon Co., Ltd., “Blendex” manufactured by GE Specialty Chemical Co., Ltd. 449 "and the like. In addition, 1 type may contain fluoroethylene resin and 2 or more types may contain it by arbitrary combinations and a ratio.

  The content of the fluoropolymer (D) is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, further preferably 0.4 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). As described above, it is particularly preferably 0.5 parts by mass or more, preferably 5 parts by mass or less, preferably 4 parts by mass or less, more preferably 3 parts by mass or less. When the content of the fluoropolymer (D) is less than 0.1 parts by mass, the effect of suppressing foam breakage due to an increase in elongational viscosity is small, and when the content exceeds 5 parts by mass, a polycarbonate resin composition was molded. Deterioration of the appearance of the molded product and reduction in mechanical strength are likely to occur.

[Other ingredients]
The polycarbonate resin composition for supercritical foam molding of the present invention may contain other components in addition to those described above as necessary, as long as desired physical properties are not significantly impaired. Examples of other components include resins other than those described above and various resin additives. In addition, 1 type may contain other components and 2 or more types may contain them by arbitrary combinations and ratios.

Other resins Examples of other resins include thermoplastic polyester resins such as polyethylene terephthalate resin, polytrimethylene terephthalate, polybutylene terephthalate resin; polyolefin resins such as polyethylene resin and polypropylene resin; polystyrene resins; polyamide resins; polyimide resins A polyetherimide resin; a polyurethane resin; a polyphenylene ether resin; a polyphenylene sulfide resin; and a polysulfone resin.
In addition, 1 type may contain other resin and 2 or more types may contain it by arbitrary combinations and ratios.

-Resin additive The resin additive may contain various resin additives other than those described above within a range not impairing the effects of the present invention. For example, an ultraviolet absorber, a dye / pigment, an antistatic agent, an antifogging agent. Agents, antiblocking agents, fluidity improvers, plasticizers, dispersants, antibacterial agents and the like. In addition, 1 type may contain resin additive and 2 or more types may contain it by arbitrary combinations and a ratio.

[Production Method of Polycarbonate Resin Composition]
There is no restriction | limiting in the manufacturing method which manufactures the polycarbonate resin composition of this invention, The manufacturing method of a well-known polycarbonate resin composition can be employ | adopted widely.
As specific examples, the polycarbonate resin (a1), the polycarbonate resin (a2), the stabilizer (B), and other components to be blended as necessary are used, for example, by using various mixers such as a tumbler and a Henschel mixer. Examples of the method include a method of melt-kneading with a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader after mixing in advance.

In addition, for example, without mixing each component in advance, or only a part of the components is mixed in advance, and fed to an extruder using a feeder and melt-kneaded to produce the polycarbonate resin composition of the present invention. You can also.
Also, for example, by mixing a part of the components in advance and supplying the resulting mixture to an extruder and melt-kneading it as a master batch, this master batch is again mixed with the remaining components and melt-kneaded. The polycarbonate resin composition of the present invention can also be produced.
In addition, for example, when mixing a component that is difficult to disperse, the component that is difficult to disperse is dissolved or dispersed in a solvent such as water or an organic solvent in advance, and kneaded with the solution or the dispersion. It can also improve sex.

[Supercritical foam molding]
The polycarbonate resin composition of the present invention is made into a foam molded product by supercritical foam molding. As the molding machine, an injection molding machine, an extrusion molding machine, a blow molding machine or the like is used, and an injection molding machine is preferably used. The gas used for supercritical foaming is preferably nitrogen gas or carbon dioxide gas.

For the supercritical foam molding, various known methods can be applied, and any of a batch type and a continuous type may be used.
As a batch type, an unfoamed solid molded product is produced by extrusion molding, injection molding, etc., the molded product is sealed in a pressure-resistant container, a supercritical gas as a foaming agent is injected, and gas is injected into the molded product by high pressure. By impregnating and depressurizing the inside of the container, bubbles are generated in the molded product to obtain a foam.

Examples of the continuous type include extrusion foam molding and injection foam molding.
In extrusion foam molding, a supercritical fluid is impregnated during resin kneading and foamed by reduced pressure during extrusion from a die.

Examples of the injection foam molding include a short shot method and a core back method. In both cases, the supercritical fluid is injected into the cylinder and melted when the resin is weighed, but the foaming process is different.
In the short shot method, a smaller amount of resin than the cavity volume is injected, bubbles are generated by pressure reduction during injection, and the cavity is filled by expanding the bubbles. In the core back method, a mold having a variable cavity volume is used, and the same amount of resin as the cavity volume is injected. After filling, the cavity volume is expanded to generate and expand bubbles to obtain a foam.
Bubble nuclei are generated by reducing the pressure in the mold to a pressure below the critical pressure of nitrogen or carbon dioxide, so that nitrogen or carbon dioxide is supersaturated, and a large number of cells are added to the supersaturated molten resin composition. This is done by generating nuclei.

[Molded body]
The polycarbonate resin composition of the present invention is molded into an arbitrary shape by supercritical foam molding and used as a molded product. There are no restrictions on the shape, pattern, color, size, etc. of the molded product, and it may be set arbitrarily according to the application of the molded product.

  Examples of the molded article include parts such as electric / electronic equipment, OA equipment, information terminal equipment, machine parts, home appliances, vehicle parts, building members, various containers, and lighting equipment. Among these, it is particularly suitable for various parts of electric / electronic devices and OA devices.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In the following description, “parts” means “parts by mass” based on mass standards unless otherwise specified.

  Each component used in the following Examples and Comparative Examples is as shown in Table 1 below.

(Examples 1-12, Comparative Examples 1-2)
[Manufacture of resin pellets]
The components described in Table 1 above were blended in the proportions (mass ratio) described in Table 2 below, mixed for 10 minutes with a tumbler, and then a twin-screw extruder “TEM26SX” manufactured by Toshiba Machine Co., Ltd. equipped with 1 vent. Kneaded under the conditions of a rotation speed of 200 rpm, a discharge rate of 20 kg / hour, and a barrel temperature of 280 ° C., the molten resin extruded into a strand is rapidly cooled in a water tank, pelletized using a pelletizer, Pellets were obtained.

[Measurement of complex elastic modulus]
After drying the pellet at 120 ° C. for 5 hours, a flat plate having a width of 13 mm, a length of 125 mm, and a thickness of 0.8 mm is injection-molded, and then cut into a strip shape having a width of 3 mm, a length of 20 mm, and a thickness of 0.8 mm. A sample was obtained. The sample used was Rheogel E-4000 manufactured by UBM, and the complex elastic modulus E ^* (Pa · s) was measured under the conditions of a measurement frequency of 1.0 Hz and a strain of 0.1%.

FIG. 1 is a graph showing the measurement results of the complex elastic modulus E ^* (Pa) of the polycarbonate resin compositions produced in Examples and Comparative Examples.
From FIG. 1, it can be seen that the polycarbonate of the example of the present invention has a wide rubber-like region as compared with Comparative Example 1. Due to this property, the foamed cell wall can have high strength in a wide temperature range, and it is considered that foam breakage is suppressed. On the other hand, in Comparative Example 2, the rubber-like region is greatly enlarged as compared with Comparative Example 1, but it is considered that since the effect of increasing the extensional viscosity described later is small, it did not have a large bubble breaking suppression effect.

[Measurement of elongational viscosity]
The extension viscosity of the obtained pellet was measured as follows.
The pellets were dried at 120 ° C. for 5 hours, and then press-molded at 270 ° C. into a shape having a width of 8 mm, a length of 1.5 mm, and a thickness of 0.8 mm to obtain a measurement sample. The sample was dried at 120 ° C. for 4 hours before the measurement, and the elongation viscosity η _E (Pa · s) was measured using a TA instrument ARES rheometer at a temperature of 190 ° C. and a strain rate of 0.1 s ^−1. It was measured.

It is a graph which shows the result of the extensional viscosity measurement of the polycarbonate resin composition obtained by the Example and the comparative example.
From FIG. 2, it can be seen that the polycarbonate of the example of the present invention has a higher elongational viscosity at high strain than the comparative example. It is considered that cell wall tearing during bubble growth was suppressed by high elongational viscosity.

[Evaluation of fluidity]
After drying the obtained pellets at 120 ° C. for 5 hours or more, using a Koka flow tester according to the method described in Appendix C of JIS K7210, per unit time of the composition under the conditions of 280 ° C. and a load of 160 kgf. The flow rate Q value (unit: × 10 ⁻² cc / sec) was measured to evaluate the fluidity. An orifice having a diameter of 1 mm and a length of 10 mm was used.
It shows that it is excellent in fluidity | liquidity (moldability), so that Q value is high.

[Evaluation of supercritical foam moldability]
The pellets of the obtained resin composition were preliminarily dried at 120 ° C. for 6 to 12 hours, and nitrogen which was put into a supercritical state using a MuCell SCF apparatus (model: SII-TRJ-10-A) manufactured by TREXEL was used. A predetermined amount is injected into the cylinder of J35EL injection molding machine manufactured by Nippon Steel Co., Ltd., mixed with the molten resin composition, injected into the mold, core backed by the core back method, and supercritical foam molding is performed. A foam having a thickness of 4 mm and a length of 50 mm × width of 50 mm was obtained.
Molding conditions are: cylinder temperature 300 ° C., mold temperature 80 ° C., cooling time 15 seconds, back pressure 15 MPa, holding pressure 80 MPa, nitrogen inflow 0.06% by mass, injection holding time 2.5 seconds, core back amount 2 mm. The core back speed was applied by applying two conditions of 1 mm / sec and 20 mm / sec.

The evaluation method was evaluated by the number n (n / 10) of defects caused by bubble breakage during 10 shots when 10 shots were molded under the same conditions at core back speeds of 1 mm / sec and 20 mm / sec. The defect was determined to be defective when the foam was in any of the following states.
-When the foam is visually observed through a fluorescent lamp, a transparent part due to a cavity is observed.
・ A clear blister is observed in the foam.

  The above evaluation results are shown in Table 2 below.

  Since the polycarbonate resin composition for supercritical foam molding of the present invention has no problem of corrosion of the mold cavity surface during supercritical foam molding, it can produce good molded products with high productivity in various supercritical foam molding, Its industrial utility is high.

Claims (7)

  A polycarbonate resin (a1) having a structural viscosity index (N value) of 1.2 or more and a viscosity average molecular weight of 20,000 or more and less than 50,000, and a viscosity having a structural viscosity index (N value) of less than 1.2 Polycarbonate resin (a2) having an average molecular weight of 10,000 or more and less than 25,000 is calculated based on the total of 100% by mass of (a1) and (a2), (a1) being 50 to 100% by mass, and (a2) being 0 to A polycarbonate resin composition for supercritical foam molding, comprising 0.01 to 0.5 parts by mass of the stabilizer (B) with respect to 100 parts by mass of the polycarbonate resin (A) containing 50% by mass.   Furthermore, the supercritical foaming of Claim 1 which contains 5-60 mass parts with respect to 100 mass parts of polycarbonate resin (A) of the polycarbonate oligomer (C) whose viscosity average molecular weight is 1,000 or more and less than 10,000. Polycarbonate resin composition for molding.   The polycarbonate resin composition for supercritical foam molding according to claim 1 or 2, wherein the viscosity average molecular weight of the polycarbonate resin (a1) is larger than the viscosity average molecular weight of the polycarbonate resin (a2), and the difference is 5,000 or more. .   The polycarbonate resin composition for supercritical foam molding according to any one of claims 1 to 3, wherein the difference in viscosity average molecular weight between the polycarbonate resin (a1) and the polycarbonate oligomer (C) is 10,000 or more.   The polycarbonate resin composition for supercritical foam molding according to any one of 1 to 4, further comprising 0.1 to 5 parts by mass of the fluoropolymer (D) with respect to 100 parts by mass of the polycarbonate resin (A). .   The gas used for supercritical foaming is nitrogen gas or carbon dioxide gas, The polycarbonate resin composition for supercritical foam molding of any one of Claims 1-5.   The molded article formed by supercritical foam molding using the polycarbonate resin composition for supercritical foam molding of any one of Claims 1-6.