Masterbatch, method for producing the same, polycarbonate resin composition, injection foamed molded article, and method for producing the same

Abstract

The present invention relates to a masterbatch comprising heat-expandable microcapsules (A) and a carrier resin composition (B). The carrier resin composition (B) is a carrier resin composition (B1) comprising an acrylic resin (C), an acrylic plasticizer (D1), and an oil-absorbing powder (E), or a carrier resin composition (B2) comprising an acrylic resin (C) and a low-molecular-weight styrene resin (D2). In the case of the carrier resin composition (B1), the acrylic plasticizer (D1) accounts for 0.1 to 4% by weight, and the oil-absorbing powder (E) accounts for 0.1% to less than 4% by weight in the masterbatch. In the case of the carrier resin composition (B2), the low-molecular-weight styrene resin (D2) accounts for 0.1% to less than 12% by weight in the masterbatch.

Description

Technical Field

[0001] The present invention relates to a masterbatch containing thermally expandable microcapsules, a method for producing the masterbatch, a polycarbonate resin composition containing the masterbatch, a mixture, an injection-molded foam article, and a method for producing the injection-molded foam article. Background Art

[0002] Thermally decomposable chemical foaming agents such as sodium bicarbonate are often used in resin injection foaming. Furthermore, heat-expandable microcapsules that expand by heating are also used in resin injection foaming. Generally, from the perspective of dispersibility and operability in the base resin, heat-expandable microcapsules are often used in the form of a masterbatch containing a chemical foaming agent and 20 to 60% by weight of heat-expandable microcapsules in a thermoplastic resin or thermoplastic elastomer. For example, Patent Document 1 describes a masterbatch containing heat-expandable microcapsules, a carrier resin containing an olefin polymer, and a lubricant. However, if the masterbatch of heat-expandable microcapsules described in Patent Document 1 is used to foam a polycarbonate resin, since the carrier resin contains an olefin polymer, whitening will occur on the surface of the injection-molded foaming body due to incompatible components of the olefin polymer, resulting in a poor appearance.

[0003] Therefore, in Patent Document 2, by using a masterbatch of heat-expandable microcapsules, an injection-molded foamed article of a polycarbonate resin composition can be obtained in which the occurrence of whitening is suppressed and the appearance is good. The masterbatch of heat-expandable microcapsules is obtained by masterbatch using a carrier resin composition comprising an acrylic resin having a weight-average molecular weight of 8,000 to 350,000 inclusive and being solid at 20°C and a plasticizer having a weight-average molecular weight of 1,000 to 20,000 inclusive and being liquid at 20°C.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-082244

[0007] Patent Document 2: International Publication No. 2019 / 208653 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, when preparing the masterbatch described in Patent Document 2, the type and amount of the plasticizer may result in poor feedability of the carrier resin composition or the mixture of the thermally expandable microcapsules and the carrier resin composition into the extruder, resulting in a low discharge rate of the melt-kneaded product.

[0010] In order to solve the above-mentioned conventional problems, the present invention provides a masterbatch of a carrier resin composition or a mixture of a thermally expandable microcapsule and a carrier resin composition, which has good feedability to an extruder and improves the discharge amount of the molten kneaded product; a method for producing the masterbatch; a polycarbonate resin composition comprising the masterbatch; the mixture; an injection-molded foam molded article; and a method for producing the injection-molded foam molded article.

[0011] Solutions to the Problem

[0012] In one or more embodiments, the present invention relates to a masterbatch comprising a heat-expandable microcapsule (A) and a carrier resin composition (B), wherein the carrier resin composition (B) is a carrier resin composition (B1) or a carrier resin composition (B2), wherein the carrier resin composition (B1) comprises an acrylic resin (C) having a weight-average molecular weight of 8,000 to 350,000 inclusive and being solid at 20° C., an acrylic plasticizer (D1) having a weight-average molecular weight of 1,000 to 20,000 inclusive and being liquid at 20° C., and an oil-absorbing powder (E), and the carrier resin composition (B2) comprises an acrylic resin (C) having a weight-average molecular weight of 8,000 to 350,000 inclusive and being liquid at 20° C. ℃, an acrylic resin (C) which is solid at 20℃, and a low-molecular-weight styrene resin (D2) which has a weight-average molecular weight of 1000 to 150000 and is liquid or solid at 20℃; when the carrier resin composition (B) is the carrier resin composition (B1), in the masterbatch, the content of the acrylic plasticizer (D1) is 0.1 wt% to 4 wt%, and the content of the oil-absorbing powder (E) is 0.1 wt% to less than 4 wt%; when the carrier resin composition (B) is the carrier resin composition (B2), in the masterbatch, the content of the low-molecular-weight styrene resin (D2) is 0.1 wt% to less than 12 wt%.

[0013] In addition, the present invention relates to a method for producing the above-mentioned masterbatch in one or more embodiments, the method comprising: a step of mixing a heat-expandable microcapsule (A) and a carrier resin composition (B); a step of supplying the obtained mixture to an extruder and melt-kneading the mixture; and a step of extruding the obtained melt-kneaded product.

[0014] In one or more embodiments, the present invention relates to a method for producing the above-mentioned masterbatch, comprising: supplying a heat-expandable microcapsule (A) and a carrier resin composition (B) to an extruder, respectively, and melt-kneading the heat-expandable microcapsule (A) and the carrier resin composition (B); and extruding the resulting melt-kneaded product.

[0015] In one or more embodiments, the present invention relates to a mixture comprising a heat-expandable microcapsule (A) and a carrier resin composition (B), wherein the heat-expandable microcapsule (A) and the carrier resin composition (B) are the heat-expandable microcapsule (A) and the carrier resin composition (B), respectively. When the carrier resin composition (B) is the carrier resin composition (B1), the mixture is a mixture of a powder and a liquid. When the carrier resin composition (B) is the carrier resin composition (B2), the mixture is a mixture of a powder and a liquid or a mixture of powders. When the mixture is fed into a twin-screw quantitative feeder, the rotation of the twin screws causes the mixture to flow within the feeder and be ejected from the feeder.

[0016] Furthermore, the present invention, in one or more embodiments, relates to a polycarbonate-based resin composition comprising the above-mentioned masterbatch and a polycarbonate-based resin.

[0017] Furthermore, the present invention, in one or more embodiments, relates to an injection-foamed product obtained by injection-foaming the polycarbonate-based resin composition.

[0018] Furthermore, in one or more embodiments, the present invention relates to a method for producing an injection-foamed article, comprising injection-foaming the polycarbonate-based resin composition.

[0019] Effects of the Invention

[0020] According to the present invention, there can be provided a masterbatch having good feedability of a carrier resin composition or a mixture of a thermally expandable microcapsule and a carrier resin composition to an extruder and an increased discharge amount of a molten kneaded product, a polycarbonate resin composition containing the masterbatch, and an injection-molded foaming molded article using the polycarbonate resin composition and a method for producing the same.

[0021] Furthermore, according to the production method of the present invention, the carrier resin composition or the mixture of the thermally expandable microcapsule and the carrier resin composition can be easily supplied to the extruder, the discharge amount of the melt-kneaded product is increased, and the productivity of the masterbatch is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic explanatory diagram of the hopper portion of a quantitative feeder used in evaluating the scattering properties of raw materials.

[0023] Figure 2 is Figure 1 CC' cross-sectional view of the hopper portion of a quantitative feeder used in the evaluation of raw material scattering properties.

[0024] Explanation of symbols

[0025] 1.2 Components of the hopper of the quantitative feeder

[0026] 3 gap

[0027] 4 Joint surface DETAILED DESCRIPTION

[0028] The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, they have discovered that by using a carrier resin composition (B1) comprising an acrylic resin (C) having a weight-average molecular weight of 8,000 to 350,000 and being solid at 20°C, an acrylic plasticizer (D1) having a weight-average molecular weight of 1,000 to 20,000 and being liquid at 20°C, and an oil-absorbing powder (E), and by adjusting the content of the acrylic plasticizer (D1) to 0.1% by weight to 4% by weight and the content of the oil-absorbing powder (E) to 0.1% by weight to less than 4% by weight in a masterbatch comprising thermally expandable microcapsules (A) and the carrier resin composition (B1), the supply efficiency of the carrier resin composition or the mixture of the thermally expandable microcapsules and the carrier resin composition to an extruder and the discharge rate of the melt-kneaded product of the thermally expandable microcapsules and the carrier resin composition can be improved. It is speculated that by using the masterbatch containing the heat-expandable microcapsules (A), the acrylic resin (C), and the acrylic plasticizer (D1) in such a manner that the content of the acrylic plasticizer (D1) is from 0.1% by weight to 4% by weight, and the content of the oil-absorbing powder (E) is from 0.1% by weight to less than 4% by weight, the carrier resin composition or the mixture of the heat-expandable microcapsules and the carrier resin composition has reduced adhesion and improved fluidity, thereby improving the supply efficiency of the carrier resin composition or the mixture of the heat-expandable microcapsules and the carrier resin composition to the extruder and the discharge amount of the melt-kneaded product of the heat-expandable microcapsules and the carrier resin composition.

[0029] Alternatively, the inventors of the present invention have discovered that by using a carrier resin composition (B2) comprising an acrylic resin (C) having a weight-average molecular weight of 8,000 to 350,000, which is solid at 20°C, and a low-molecular-weight styrene resin (D2) having a weight-average molecular weight of 1,000 to 150,000, which is liquid or solid at 20°C, and by adjusting the content of the low-molecular-weight styrene resin (D2) in a masterbatch comprising thermally expandable microcapsules (A) and the carrier resin composition (B2) to 0.1% by weight or more and less than 12% by weight, the supplyability of the carrier resin composition or a mixture of the thermally expandable microcapsules and the carrier resin composition to an extruder and the discharge amount of the melt-kneaded product of the thermally expandable microcapsules and the carrier resin composition can be improved. It is speculated that by using a low molecular weight styrene-based resin (D2) in a predetermined amount that has a shear force reducing effect during kneading and does not reduce the fluidity of the carrier resin composition or the mixture of the heat-expandable microcapsules and the carrier resin composition, the supply efficiency of the carrier resin composition or the mixture of the heat-expandable microcapsules and the carrier resin composition to the extruder and the discharge amount of the melt-kneaded product of the heat-expandable microcapsules and the carrier resin composition are improved.

[0030] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described below.

[0031] Thermally expandable microcapsules (A)

[0032] Thermally expandable microcapsules (A) are encapsulated foaming agents consisting of a liquid, low-boiling-point compound encapsulated by a thermoplastic polymer shell. The pressure from the vaporized low-boiling-point compound caused by heating within the injection molding machine barrel causes the capsules to expand and function as a foaming agent. Suitable examples of thermally expandable microcapsules (A) include those described in Japanese Patent Application Laid-Open No. 2011-16884. Specifically, thermally expandable microcapsules (A) have a core-shell structure, with the core composed of one or more compounds having a boiling point of 10°C to 330°C, and the shell enclosing the core and composed of a thermoplastic resin.

[0033] The core may be composed of one or more compounds selected from compounds having a boiling point of 10°C or higher and 330°C or higher. The compound constituting the core is not particularly limited, and examples thereof include hydrocarbons, alcohols, ketones, and the like. The hydrocarbon is not particularly limited, and examples thereof include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, and structural isomers thereof. The compound constituting the core is preferably one or more hydrocarbons having a boiling point of 10°C or higher and 330°C or lower, more preferably one or more hydrocarbons having a boiling point of 30°C or higher and 280°C or lower, and even more preferably one or more hydrocarbons having a boiling point of 30°C or higher and 200°C or lower. By using a compound having a boiling point of 10°C or higher, the heat-expandable microcapsule (A) can be easily masterbatched. In addition, by using a compound having a boiling point of 330°C or lower, the dispersibility during polymerization becomes good, making it easy to manufacture the heat-expandable microcapsules.

[0034] As the monomer component of the thermoplastic resin constituting the shell of the heat-expandable microcapsule (A), for example, one or more monomers selected from the group consisting of nitrile monomers, (meth)acrylate monomers, aromatic vinyl monomers, vinyl monomers having a carboxyl group, diene monomers, and monomers having one or more reactive functional groups selected from the group consisting of a methylol group, a hydroxyl group, an amino group, an epoxy group, and an isocyanate group can be used.

[0035] From the perspective of utilizing the shell of the heat-expandable microcapsule (A) to suppress the decomposition of the main chain of a resin component such as a polycarbonate resin, the thermoplastic resin constituting the shell preferably comprises one or more monomers selected from the group consisting of the aforementioned nitrile monomers, (meth)acrylate monomers, aromatic vinyl monomers, and vinyl monomers having a carboxyl group. Furthermore, the thermoplastic resin constituting the shell may appropriately contain a chain transfer agent and a monomer having a reactive functional group.

[0036] Examples of the nitrile monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile.

[0037] Examples of the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. In the present invention, the "(meth)acrylate" may be either a methacrylate or an acrylate.

[0038] Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, p-nitrostyrene, and chloromethylstyrene.

[0039] Examples of the vinyl monomer having a carboxyl group include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, and chloromaleic acid, and anhydrides thereof; and unsaturated dicarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate.

[0040] Examples of the diene monomer include butadiene, isoprene, and chloroprene.

[0041] Examples of monomers having one or more reactive functional groups selected from the group consisting of a methylol group, a hydroxyl group, an amino group, an epoxy group, and an isocyanate group (hereinafter also referred to as “monomers having a reactive functional group”) include N-methylol (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, glycidyl (meth)acrylate, glyceryl mono(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, p-hydroxystyrene, and blocked isocyanates. Examples of blocked isocyanates include isocyanate compounds (e.g., diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, toluene diisocyanate) blocked with phenol, alcohol, dimethyl malonate, diethyl malonate, ethyl acetoacetate, oxime, dimethylpyrazole, methyl ethyl ketone oxime, caprolactam, etc. In the present invention, "(meth)acrylamide" may be either methacrylamide or acrylamide.

[0042] The chain transfer agent is not particularly limited as long as it is a chain transfer agent used in conventional free radical polymerization. Specifically, a thiol compound can be used. Examples of the thiol compound that can be used appropriately include alkyl mercaptans such as n-dodecyl mercaptan, n-octyl mercaptan, tert-dodecyl mercaptan, and n-octadecyl mercaptan, 2-mercaptobenzothiazole, bromotrichloromethane, α-methylstyrene dimer, and 2-ethylhexyl thioglycolate.

[0043] From the perspective of preventing decomposition of resin components such as polycarbonate resins and improving the surface properties of the injection-molded foaming article, the concentration of structural units derived from one or more monomers selected from carboxyl group-containing monomers and amino group-containing monomers in the thermoplastic resin constituting the shell is preferably 12 mmol / g or less, more preferably 10 mmol / g or less, even more preferably 8 mmol / g or less, even more preferably 5 mmol / g or less, even more preferably 3 mmol / g or less, particularly preferably 1 mmol / g or less, and most preferably substantially no carboxyl group-containing monomers and / or amino group-containing monomers are contained. The lower limit of the carboxyl group concentration in the thermoplastic resin constituting the shell can be 0.001 mmol / g or more.

[0044] From the perspective of suppressing the decomposition of the main chain of a resin such as a polycarbonate resin, the concentration of the alkaline substance in the heat-expandable microcapsule (A) is preferably 2000 ppm or less, more preferably 1000 ppm or less, and even more preferably 800 ppm or less. If it exceeds 2000 ppm, there is concern that the molecular weight of the polycarbonate resin may be reduced and the strength of the molded article may be reduced. Examples of the alkaline substance include ionic components derived from hydroxides (salts) of alkali metals and / or alkaline earth metals, and specifically, ionic components derived from hydroxides (salts) of metals such as Li, Na, Mg, K, Ca, and Ba.

[0045] It is expected that the pH of the heat-expandable microcapsule (A) is near neutral. The heat-expandable microcapsule (A) can generally be produced as follows: in an aqueous dispersion medium, a mixture containing a polymerizable monomer and a low-boiling-point compound forming a core is subjected to suspension polymerization, thereby enclosing the low-boiling-point compound as a core component in a shell of a thermoplastic resin composed of monomers. It is expected that the pH of the heat-expandable microcapsule (A) is adjusted during such polymerization. Generally speaking, a method of adding potassium hydrogen phosphate buffer can be cited. The preferred range of pH is 6.0 or more and 8.0 or less, a more preferred range is 6.0 or more and 7.5 or less, and a further preferred range is 6.0 or more and 7.0 or less. The glass electrode method can be cited as a method for measuring pH. In the glass electrode method, two electrodes, a glass electrode and a reference electrode, are used to detect the potential difference generated between the electrodes and convert it into a pH value.

[0046] From the perspective of not causing a decrease in the molecular weight of the polycarbonate resin, in the heat-expandable microcapsule (A), the thermoplastic resin constituting the shell preferably satisfies the following conditions. The temperature at which the weight loss of 5% of the pellets obtained by kneading 95 parts by weight of the polycarbonate resin and 5 parts by weight of the thermoplastic resin constituting the shell at 300°C using a φ30 mm single-screw extruder is preferably 200°C or higher, more preferably 220°C or higher, further preferably 240°C or higher, and particularly preferably 260°C or higher. Furthermore, with respect to the weight average molecular weight (Mw) and number average molecular weight (Mn) of the pellets, the retention rates of Mw and Mn relative to the Mw and Mn of the polycarbonate resin are preferably in the range of 60% or higher, more preferably 80% or higher, further preferably 90% or higher, and particularly preferably 95% or higher, respectively.

[0047] The average particle size (unexpanded) of the heat-expandable microcapsules (A) is preferably 0.5 μm to 50 μm, more preferably 0.7 μm to 50 μm, even more preferably 1.0 μm to 45 μm, even more preferably 1.0 μm to 40 μm, and particularly preferably 1.0 μm to 35 μm. The maximum particle size of the heat-expandable microcapsules (A) when heated is in the range of about 3 to 5 times the average particle size when unexpanded. When the average particle size when unexpanded is 0.5 μm to 50 μm, the particle size when expanded is about 1.5 to 250 μm, which significantly suppresses the decrease in Charpy impact strength and surface impact strength during foaming. The average particle size of the heat-expandable microcapsules (A) when unexpanded can be measured using a particle size distribution analyzer, specifically a particle size distribution analyzer SALD-3000J manufactured by Shimadzu Corporation.

[0048] The maximum expansion temperature (also called the maximum foaming temperature) of the heat-expandable microcapsule (A) is preferably 180°C to 300°C, more preferably 190°C to 290°C, even more preferably 200°C to 280°C, and particularly preferably 210°C to 270°C. In the present invention, the maximum expansion temperature of the heat-expandable microcapsule (A) can be measured by the measurement method described in Japanese Patent No. 5484673. Specifically, a "TMA measurement" is performed using a TMA-7 manufactured by PerkinElmer. Approximately 0.25 mg of a sample is placed in a container, the temperature is increased at a heating rate of 5°C / min, and the height displacement is continuously measured. The temperature at which the height displacement of the sample in the container reaches the maximum is defined as the maximum expansion temperature. When the maximum expansion temperature of the heat-expandable microcapsule (A) is within the above range, it matches the molding temperature of the polycarbonate resin, making it easy to obtain a low-density, high-strength injection-molded foam product.

[0049] <Carrier resin composition (B1)>

[0050] The carrier resin composition (B1) comprises an acrylic resin (C) having a weight-average molecular weight of 8,000 to 350,000, which is solid at 20°C; an acrylic plasticizer (D1) having a weight-average molecular weight of 1,000 to 20,000, which is liquid at 20°C; and an oil-absorbing powder (E). In a masterbatch comprising the heat-expandable microcapsules (A) and the carrier resin composition (B1), the content of the acrylic plasticizer (D1) is 0.1% to 4% by weight, and the content of the oil-absorbing powder (E) is 0.1% to less than 4% by weight. This improves the feedability of the carrier resin composition (B1), particularly the mixture of the heat-expandable microcapsules (A) and the carrier resin composition (B1), into the extruder and the discharge rate of the melt-kneaded product of the heat-expandable microcapsules and the carrier resin composition.

[0051] 《Acrylic Resin (C)》

[0052] The weight average molecular weight of the acrylic resin (C) is 8,000 to 350,000, preferably 10,000 to 330,000, more preferably 10,000 to 300,000, even more preferably 10,000 to 280,000, even more preferably 14,000 to 330,000, even more preferably 14,000 to 300,000, even more preferably 14,000 to 280,000, even more preferably 14,000 to 200,000, and particularly preferably 14,000 to 100,000. Alternatively, the weight average molecular weight of the acrylic resin (C) is preferably 16,000 or more and 330,000 or less, more preferably 16,000 or more and 300,000 or less, even more preferably 16,000 or more and 280,000 or less, even more preferably 16,000 or more and 200,000 or less, and particularly preferably 16,000 or more and 100,000 or less. Alternatively, the weight average molecular weight of the acrylic resin (C) is preferably 19,000 or more and 330,000 or less, more preferably 19,000 or more and 300,000 or less, even more preferably 19,000 or more and 280,000 or less, even more preferably 19,000 or more and 200,000 or less, and particularly preferably 19,000 or more and 100,000 or less. In the present invention, the weight average molecular weight and number average molecular weight of the resin are measured by GPC (gel permeation chromatography).

[0053] The acrylic resin (C) is solid at 20°C. This provides excellent handling properties and improves the processability of the masterbatch. From the viewpoint of handling properties, the acrylic resin (C) is preferably solid at 20°C to 25°C (room temperature).

[0054] From the viewpoint of the processability of the masterbatch, the glass transition temperature of the acrylic resin (C) is preferably 20°C to 150°C, more preferably 25°C to 140°C, and even more preferably 25°C to 130°C.

[0055] The acrylic resin (C) is not particularly limited. For example, from the viewpoint of compatibility with the polycarbonate resin, it is preferably an acrylic resin comprising acrylic resin particles (a) having an average particle size of 50 μm to 500 μm, and acrylic resin particles (b) having an average particle size of 0.05 μm to 0.5 μm covering the acrylic resin particles (a).

[0056] It is desired that the average particle size of the acrylic resin particles (a) is 50 μm or more and 500 μm or less, preferably 75 μm or more and 300 μm or less, and more preferably 100 μm or more and 250 μm or less. Acrylic resin particles (a) having the above average particle size can be obtained by suspension polymerization. When the average particle size of the acrylic resin particles (a) is 50 μm or more, the filterability becomes good, and when it is 500 μm or less, when the particulate compounding agent is powder-mixed in the acrylic resin (C), it can be uniformly mixed. The average particle size of the acrylic resin particles (a) is measured using Microtrack MT3300 manufactured by Microtrac BEL Co., Ltd.

[0057] In the acrylic resin (C), coating the acrylic resin particles (a) with the acrylic resin particles (b) means that the entire surface of the acrylic resin particles (a) may be coated with the acrylic resin particles (b), or the surface of the acrylic resin particles (a) may be partially coated with the acrylic resin particles (b). Preferably, at least 50% of the surface area of ​​the acrylic resin particles (a) is coated with the acrylic resin particles (b), and more preferably at least 60% is coated. When the coated surface area is 50% or more, the powder properties of the acrylic resin (C) are improved.

[0058] It is preferred that the average particle size of the acrylic resin particles (a) is increased by 3% or more and 50% or less compared to before coating by coating the acrylic resin particles (a) with acrylic resin particles (b). When the change in the acrylic resin particles (a) is less than 3%, acrylic resin particles (a) remain in the system, and as a result, there is a tendency to make it difficult to improve the filterability. That is, the average particle size of the acrylic resin (C) is preferably 3% or more and 50% or less larger than the average particle size of the acrylic resin particles (a). The average particle size of the acrylic resin (C) is measured using Microtrac MT3300 manufactured by Microtrac-Bel Co., Ltd.

[0059] From the viewpoint of easily suppressing the dust accompanying the polymer obtained by suspension polymerization, the acrylic resin particles (a) are preferably composed of more than 30% by weight and less than 100% by weight of (meth)acrylate, and more than 0% by weight and less than 70% by weight of a vinyl monomer that can be copolymerized with the (meth)acrylate. More preferably, they are composed of more than 70% by weight and less than 100% by weight of (meth)acrylate, and more than 0% by weight and less than 30% by weight of a vinyl monomer that can be copolymerized with the (meth)acrylate. In the acrylic resin particles (a), when the content of the structural unit from the (meth)acrylate is more than 30% by weight, the compatibility with the acrylic resin particles (b) is good and the molding process is good. In the present invention, "(meth)acrylic acid" can be methacrylic acid or acrylic acid.

[0060] The (meth)acrylate is not particularly limited. Examples thereof include alkyl acrylates having an alkyl group with 10 or fewer carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; and alkyl methacrylates having an alkyl group with 10 or fewer carbon atoms, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. These (meth)acrylates may be used alone or in combination of two or more. From the perspective of obtaining a high-quality molded article when combined with the acrylic resin particles (b), the (meth)acrylate is preferably one or more selected from the group consisting of methyl methacrylate, butyl methacrylate, ethyl acrylate, and butyl acrylate.

[0061] In addition, the vinyl monomers copolymerizable with (meth)acrylates are not particularly limited, and examples thereof include aromatic vinyl monomers such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinyl carboxylic acid monomers such as acrylic acid and methacrylic acid; vinyl nitrile monomers such as acrylonitrile and methacrylonitrile; vinyl halide monomers such as vinyl chloride, vinyl bromide, and chloroprene; olefins such as vinyl acetate, ethylene, propylene, butylene, butadiene, and isobutylene; olefin halides; polyfunctional monomers such as allyl methacrylate, diallyl phthalate, triallyl cyanurate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, divinylbenzene, and glycidyl methacrylate. These vinyl monomers may be used alone or in combination of two or more. Among these, from the perspective of obtaining a high-quality molded article when combined with the acrylic resin particles (b), the copolymerizable vinyl monomers are preferably one or more selected from the group consisting of styrene, α-methylstyrene, acrylic acid, methacrylic acid, acrylonitrile, vinyl acetate, allyl methacrylate, and glycidyl methacrylate.

[0062] The acrylic resin particles (a) may be particles of a polymer obtained by suspension polymerization, copolymerization or graft polymerization of one or more of the above-mentioned monomers, or a polymer obtained by itself or a mixed polymer.

[0063] As the dispersion stabilizer in the suspension polymerization, for example, conventional inorganic dispersants and organic dispersants can be used. Examples of inorganic dispersants include magnesium carbonate and tricalcium phosphate. Examples of organic dispersants include starch, gelatin, acrylamide, partially saponified polyvinyl alcohol (PVA), partially saponified polymethyl methacrylate, polyacrylic acid, salts of polyacrylic acid, cellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, polyoxyalkylenes, polyvinyl pyrrolidone, polyvinyl imidazole, sulfonated polystyrene and other natural polymer dispersants and synthetic polymer dispersants, as well as low molecular weight dispersants (also referred to as emulsifiers) such as alkylbenzene sulfonates and fatty acid salts. From the viewpoint of suppressing the decomposition of polycarbonate resin, polyoxyalkylenes such as PVA or polyethylene oxide are preferred.

[0064] Examples of the polymerization initiator in suspension polymerization include peroxides such as benzoyl peroxide and lauroyl peroxide, and azo compounds such as azobisisobutyronitrile.

[0065] A chain transfer agent may also be used to adjust the molecular weight. Examples of chain transfer agents include alkyl mercaptans having 2 to 18 carbon atoms; mercapto acids such as thioglycolates and β-mercaptopropionic acid; and aromatic mercaptans such as benzyl mercaptan, thiophenol, thiocresol, and thionaphthol. Examples of alkyl mercaptans having 2 to 18 carbon atoms include n-dodecyl mercaptan, n-octyl mercaptan, tert-dodecyl mercaptan, and n-octadecyl mercaptan. Of these, alkyl mercaptans having 4 to 12 carbon atoms are preferred. Examples of thioglycolates include 2-ethylhexyl thioglycolate.

[0066] The added amounts of the dispersion stabilizer, polymerization initiator, and chain transfer agent can be appropriately set according to the monomers used and the physical properties of the target suspended polymer particles (acrylic resin particles (a)).

[0067] The method for producing suspended polymer particles is not particularly limited, and all generally available methods can be used. Examples include: a method in which a monomer or monomer mixture is suspended in water and the polymerization reaction is directly carried out; a method in which a portion of the monomer or monomer mixture is suspended in water, the polymerization reaction is initiated, and as the polymerization reaction proceeds, the remaining monomer or monomer mixture aqueous suspension is added to a polymerization reaction tank in a single stage, in multiple stages, or continuously; a method in which a portion of the monomer or monomer mixture is suspended in water, the polymerization reaction is initiated, and as the polymerization reaction proceeds, the remaining monomer or monomer mixture is added to a polymerization reaction tank in a single stage, in multiple stages, or continuously.

[0068] The adding method of polymerization initiator and chain-transfer agent is not particularly limited. Preferably, after polymerization initiator and chain-transfer agent are dissolved in monomer, monomer is suspended in water, and the method for directly implementing polyreaction is carried out. The time required for polymerization is different according to the type and amount of polymerization initiator and polymerization temperature etc., and is usually more than 1 hour and less than 24 hours. In addition, also can when suspension polymerization, the additive that usually adds during the forming processing of plastics such as plasticizer, lubricant, stabilizer and ultraviolet light absorber is added in monomer.

[0069] The average particle size of the acrylic resin particles (b) is preferably 0.05 μm or more and 0.5 μm or less, preferably 0.06 μm or more and 0.3 μm or less. Acrylic resin particles (b) having the above average particle size can be obtained by emulsion polymerization. When the average particle size of the acrylic resin particles (b) is within the above range, the processability during molding of the acrylic resin (C) and the impact resistance and transparency of the resulting molded product tend to be good. The average particle size of the acrylic resin particles (b) is measured using Microtrac MT3300 manufactured by Microtrac-Bel Co., Ltd.

[0070] The acrylic resin particles (b) are preferably composed of 30-100% by weight of a (meth)acrylate and 0-70% by weight of a vinyl monomer copolymerizable with the (meth)acrylate. More preferably, they are polymerized particles formed by polymerizing 50-90 parts by weight of latex particles (b1) composed of 50-100% by weight of a (meth)acrylate, 0-40% by weight of an aromatic vinyl monomer, 0-10% by weight of a vinyl monomer copolymerizable with the (meth)acrylate, and 0-5% by weight of a polyfunctional monomer, with a monomer mixture (b2) containing 10-100% by weight of a (meth)acrylate, 0-90% by weight of an aromatic vinyl monomer, 0-25% by weight of an acrylonitrile monomer, and 0-20% by weight of a vinyl monomer copolymerizable with the (meth)acrylate, with the total of the latex particles (b1) and the monomer mixture (b2) being 100 parts by weight. In this specification, a range represented by "... to..." is equivalent to a range represented by "... or more and... or less."

[0071] The (meth)acrylate constituting the acrylic resin particles (b) is not particularly limited, and for example, the (meth)acrylates listed in the description of the acrylic resin particles (a) can be suitably used. Furthermore, the aromatic vinyl monomer, acrylonitrile monomer, polyfunctional monomer, and other copolymerizable vinyl monomers constituting the acrylic resin particles (b) are not particularly limited, and for example, the monomers listed in the description of the acrylic resin particles (a) can be suitably used.

[0072] The acrylic resin particles (b) are more preferably emulsion polymer particles obtained by graft polymerization of 70 to 95 parts by weight of latex particles (b1) and 5 to 30 parts by weight of a monomer mixture (b2), wherein the latex particles (b1) are obtained by emulsion polymerization of a monomer mixture (a) comprising 50 to 95 parts by weight of methyl methacrylate, 5 to 50 parts by weight of a methacrylate having an alkyl group having 2 to 8 carbon atoms, and 0 to 20 parts by weight of a vinyl monomer copolymerizable with these, and the monomer mixture (b2) comprises 20 to 80 parts by weight of one or more monomers selected from methacrylates other than acrylic esters and methyl methacrylate, 20 to 80 parts by weight of methyl methacrylate, and 0 to 20 parts by weight of a vinyl monomer copolymerizable with these, and the total amount of the latex particles (b1) and the monomer mixture (b2) is 100 parts by weight. Specifically, preferably, the present invention relates to emulsion polymer particles obtained by graft polymerizing 5 to 30 parts by weight of a monomer mixture (II) comprising 20 to 80% by weight of one or more monomers selected from methacrylates other than acrylates and methyl methacrylate, 20 to 80% by weight of methyl methacrylate, and 0 to 20% by weight of a vinyl monomer copolymerizable with these monomers, in the presence of a polymer latex obtained by emulsion polymerizing 70 to 95 parts by weight of a monomer mixture (I) comprising 50 to 95% by weight of methyl methacrylate, 5 to 50% by weight of a methacrylate having an alkyl group having 2 to 8 carbon atoms, and 0 to 20% by weight of a vinyl monomer copolymerizable with these monomers, wherein the total of the monomer mixture (I) and the monomer mixture (II) is 100 parts by weight.

[0073] The acrylic resin particles (b) are more preferably emulsion polymer particles obtained by polymerizing 100 parts by weight of the second-stage polymer particles (latex particles (b1)) with 11 to 67 parts by weight of a monomer mixture containing 60 to 100% by weight of a (meth)acrylate and 0 to 40% by weight of a vinyl monomer copolymerizable with the (meth)acrylate, wherein the second-stage polymer particles are obtained by polymerizing 10 to 60 parts by weight of the first-stage polymer with 60 to 99.9% by weight of an alkyl acrylate and 0 to 30% by weight of a vinyl monomer copolymerizable with the (meth)acrylate. The first stage polymer is obtained by polymerizing 40 to 90 parts by weight of a monomer mixture (IV) containing 40 to 99.99 parts by weight of methyl methacrylate, 0 to 59.99 parts by weight of a vinyl monomer copolymerizable therewith, and 0.01 to 10 parts by weight of a polyfunctional monomer, wherein the total amount of the monomer mixture (III) and the monomer mixture (IV) is 100 parts by weight. Specifically, the three-layered emulsion polymer particles are obtained by subjecting 10 to 60 parts by weight of a monomer mixture (III) comprising 40 to 99.99 wt % of methyl methacrylate, 0 to 59.99 wt % of a vinyl monomer copolymerizable with the methyl methacrylate, and 0.01 to 10 wt % of a multifunctional monomer to emulsion polymerization, and then, in the presence of the latex of the obtained first-stage polymer, reacting 60 to 99.9 wt % of an alkyl acrylate, 0 to 39.9 wt % of a vinyl monomer copolymerizable with the methyl methacrylate, and 0.1 to 5 wt % of a multifunctional monomer to form a three-layered emulsion polymer. The invention relates to a method for preparing an emulsion polymer latex comprising: emulsion polymerization of 40 to 90 parts by weight of a monomer mixture (IV) containing 60 to 100 parts by weight of a (meth)acrylate and 0 to 40 parts by weight of a vinyl monomer copolymerizable therewith, to obtain a second-stage polymer latex, wherein the total amount of the monomer mixture (III) and the monomer mixture (IV) is 100 parts by weight, and in the presence of 100 parts by weight of the solid component (latex particles (b1)) of the obtained second-stage polymer latex, 11 to 67 parts by weight of a monomer mixture (b2) containing 60 to 100 parts by weight of a (meth)acrylate and 0 to 40 parts by weight of a vinyl monomer copolymerizable therewith are further polymerized to obtain the emulsion polymer particles.

[0074] The glass transition temperature of the latex particles (b1) is preferably 0° C. or lower, more preferably -30° C. or lower. When the glass transition temperature of the latex particles (b1) is 0° C. or lower, the impact resistance of the injection-molded foaming article tends to be improved.

[0075] The acrylic resin (C) preferably contains 22 parts by weight or more and 100 parts by weight or less of acrylic resin particles (b) per 100 parts by weight of acrylic resin particles (a), more preferably 25 parts by weight or more and 100 parts by weight or less, and even more preferably 30 parts by weight or more and 100 parts by weight or less. If the amount of acrylic resin particles (b) is less than 22 parts by weight per 100 parts by weight of acrylic resin particles (a), there is a concern that filterability may not be improved. Furthermore, if the amount of acrylic resin particles (b) exceeds 100 parts by weight per 100 parts by weight of acrylic resin particles (a), there is a concern that the moisture content of the acrylic resin (C) after dehydration may increase.

[0076] The acrylic resin (C) is not particularly limited and can be produced, for example, as described below. First, a suspension containing acrylic resin particles (a) is prepared by suspension polymerization, and an emulsion polymerization latex containing acrylic polymer particles (b) is prepared by emulsion polymerization. Next, the above-mentioned suspension is mixed with the above-mentioned emulsion polymerization latex. Next, the solid content concentration (the total concentration of acrylic polymer particles (a) and acrylic polymer particles (b)) in the obtained mixed suspension is adjusted to be greater than 25% by weight and less than 35% by weight. Next, in the mixed suspension after adjusting the solid content concentration, an electrolyte aqueous solution is added at a temperature below the Vicat softening temperature of the acrylic polymer particles (b), and after heating to a temperature higher than the Vicat softening temperature of the acrylic polymer particles (b), the acrylic resin (C) is recovered by solid-liquid separation. Through the above-mentioned manufacturing method, the surface of the acrylic polymer particles (a) can be evenly coated with the acrylic polymer particles (b), and the residual acrylic polymer particles (b) that cause the deterioration of filterability can be greatly reduced.

[0077] The method of mixing a suspension containing acrylic resin particles (a) obtained by suspension polymerization and an emulsion polymerization latex containing acrylic polymer particles (b) obtained by emulsion polymerization is preferably to add the emulsion polymerization latex to the suspension under stirring, or to add the suspension to the emulsion polymerization latex under stirring.

[0078] Regarding the solid content ratio of the suspension containing acrylic resin particles (a) to the emulsion polymerization latex containing acrylic polymer particles (b), the acrylic polymer particles (b) are preferably 22 parts by weight or more and 100 parts by weight or less, more preferably 25 parts by weight or more and 100 parts by weight or less, and even more preferably 30 parts by weight or more and 100 parts by weight or less, per 100 parts by weight of the acrylic resin particles (a). When the acrylic polymer particles (b) are 22 parts by weight or more per 100 parts by weight of the acrylic resin particles (a), the residual acrylic resin particles (b) in the system are reduced, resulting in improved filterability. In addition, when the acrylic polymer particles (b) are 100 parts by weight or less per 100 parts by weight of the acrylic resin particles (a), the moisture content of the resulting acrylic resin (C) after dehydration is reduced.

[0079] When the above-mentioned suspension is mixed with emulsion polymerization latex, the solid component concentration of suspension and emulsion polymerization latex is not particularly limited, and directly using the emulsion polymerization latex or suspension polymerization suspension obtained by common polymerization operation is the simplest in manufacturing, thus preferred. Usually, the solid component concentration (concentration of acrylic resin particles (a)) of the suspension comprising acrylic resin particles (a) is preferably more than 25 weight % and less than 55 weight %, more preferably more than 30 weight % and less than 45 weight %, further preferably more than 33 weight % and less than 45 weight %, particularly preferably more than 35 weight % and less than 40 weight %. The solid component concentration (concentration of acrylic resin particles (b)) of the emulsion polymerization latex comprising acrylic resin particles (b) is preferably more than 25 weight % and less than 55 weight %, more preferably more than 25 weight % and less than 45 weight %, further preferably more than 30 weight % and less than 45 weight %, particularly preferably more than 30 weight % and less than 40 weight %. The temperature during mixing is preferably 5° C. or higher. If it is lower than 5° C., the effective amount of the subsequent heat treatment operation tends to be excessively large, which is not preferable.

[0080] When adding an electrolyte aqueous solution, the solid content concentration (concentration of polymer particles) in the above-mentioned mixed suspension is preferably 25% by weight or more and 35% by weight or less, more preferably 27% by weight or more and 33% by weight or less. When the concentration of the polymer particles (solid content) in the mixed suspension is 25% by weight or more when adding an electrolyte aqueous solution, the generation of micro-agglomerates with a particle size of 50 μm or less in the mixed suspension after adding an electrolyte aqueous solution and performing heat treatment can be suppressed, and filterability becomes good, and the water content of the acrylic resin (C) after dehydration becomes low. In addition, when the concentration of the polymer particles in the mixed suspension is 35% by weight or less when adding an electrolyte aqueous solution, the generation of secondary agglomerates via acrylic resin particles (b) can be suppressed, and the water content of the acrylic resin (C) after dehydration becomes low.

[0081] The above-mentioned aqueous electrolyte solution is preferably added to the above-mentioned mixed suspension under stirring. Through this operation, the acrylic resin particles (b) as emulsion polymer particles coagulate (precipitate) on the surface of the acrylic resin particles (a) as suspension polymer particles, coating the surface of the acrylic resin particles (a). The addition of the above-mentioned aqueous electrolyte solution must be implemented after the suspension of suspension polymerization is mixed with the emulsion polymerization latex. The reason is that when the suspension of suspension polymerization and the emulsion polymerization latex are mixed, if the aqueous electrolyte solution is present, the shape of the generated acrylic resin (C) becomes skewed, not only the water content becomes higher after dehydration, but also uncoagulated acrylic resin particles (b) remain, and there is a tendency for the filterability to deteriorate extremely. For example, after adding the aqueous electrolyte solution to the suspension of suspension polymerization, when the emulsion polymerization latex is added, the problem of a significant increase in the amount of acrylic polymer particles (b) remaining will occur, which will lead to a decrease in the coating uniformity of the acrylic resin particles (b) on the surface of the acrylic resin particles (a) and a deterioration in the filterability.

[0082] As the above-mentioned electrolyte aqueous solution, an organic acid, an organic acid salt, an inorganic acid, and an inorganic salt aqueous solution having a property of causing the acrylic resin particles (b) to condense / solidify can be appropriately used. As the above-mentioned electrolyte aqueous solution, for example, there can be mentioned: aqueous solutions of inorganic salts such as sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, potassium iodide, sodium iodide, potassium sulfate, sodium sulfate, ammonium sulfate, ammonium chloride, sodium nitrate, potassium nitrate, calcium chloride, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, barium chloride, ferrous chloride, ferric chloride, magnesium chloride, ferric sulfate, aluminum sulfate, potassium alum, and iron alum; aqueous solutions of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; organic acids such as acetic acid and formic acid and their aqueous solutions; aqueous solutions of organic acid salts such as sodium acetate, calcium acetate, sodium formate, and calcium formate; etc. These can be used alone or in combination of two or more. Among them, aqueous solutions of inorganic salts such as sodium chloride, potassium chloride, sodium sulfate, ammonium chloride, calcium chloride, magnesium chloride, magnesium sulfate, barium chloride, ferrous chloride, aluminum sulfate, potassium alum, and iron alum, and aqueous solutions of inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid can be suitably used from the viewpoints of uniformity of coating the surfaces of the acrylic resin particles (a) with the acrylic resin particles (b), significant reduction in residual acrylic polymer particles (b) which causes deterioration in filterability, and ease of drainage treatment.

[0083] The concentration of the aqueous electrolyte solution is preferably 0.001% by weight or more, more preferably 0.1% by weight or more, and even more preferably 1% by weight or more. If the concentration of the aqueous electrolyte solution is less than 0.001% by weight, a large amount of aqueous electrolyte solution must be added to agglomerate the acrylic resin particles (b), which may increase the effective amount used in the subsequent heat treatment operation.

[0084] The addition of the aqueous electrolyte solution must be carried out at a temperature below the Vicat softening temperature of the acrylic resin particles (b). If the temperature of the mixed suspension exceeds the Vicat softening temperature of the acrylic resin particles (b) during the addition of the aqueous electrolyte solution, there is a concern that the shape of the resulting acrylic resin (C) may become distorted and the water content may increase after dehydration. Unsolidified acrylic resin particles (b) may remain, leading to a tendency for filterability to deteriorate significantly, and there is a tendency for agglomeration between acrylic resin particles (C) to occur frequently.

[0085] Preferably, after adding an aqueous electrolyte solution to the mixed suspension, the aqueous electrolyte solution is an acidic aqueous solution. If the mixed suspension after granulation is acidic, it is neutralized with an alkali such as sodium hydroxide, or if the aqueous electrolyte solution is a neutral aqueous solution, it is directly heat-treated at a temperature higher than the Vicat softening temperature of the acrylic polymer particles (b), for example, 50°C to 120°C. The heat treatment densifies the agglomerates of the acrylic polymer particles (b) coating the surfaces of the acrylic polymer particles (a), and the water content of the resulting acrylic resin (C) is reduced. Subsequently, dehydration and drying are performed by conventional methods to obtain the acrylic resin (C).

[0086] 《Acrylic plasticizer (D1)》

[0087] The weight average molecular weight of the acrylic plasticizer (D1) is 1,000 to 20,000, preferably 1,000 to 18,000, more preferably 1,000 to 15,000, and even more preferably 1,000 to 13,000. When the weight average molecular weight of the acrylic plasticizer (D1) is within the above range, the shear viscosity of the carrier resin composition (B1) at 130°C can easily reach 1.0×10 2 Pa·s or above and 1.0×10 6 Pa·s or less, and on this basis, the compatibility with polycarbonate resins is also good. The shear viscosity of the carrier resin composition (B1) at 130°C is 1.0×10 2 Pa·s or above and 1.0×10 6 When the viscosity is Pa·s or less, the heat-expandable microcapsule (A) can be easily and uniformly dispersed in the carrier resin composition (B1).

[0088] The acrylic plasticizer (D1) is liquid at 20° C. This improves the processability of the masterbatch.

[0089] The viscosity of the acrylic plasticizer (D1) at 25°C is preferably 300 mPa·s or more and 100,000 mPa·s or less, more preferably 350 mPa·s or more and 90,000 mPa·s or less, and even more preferably 400 mPa·s or more and 80,000 mPa·s or less. When the viscosity of the acrylic plasticizer at 25°C is within the above range, a shear viscosity of 1.0×10 2 Pa·s or above and 1.0×10 6 The carrier resin composition (B1) has a viscosity of Pa·s or less. The viscosity of the acrylic plasticizer at 25° C. can be measured using an E-type viscometer in accordance with JIS Z8803-1991.

[0090] The acrylic plasticizer (D1) may be a generally known acrylic plasticizer, but preferably a non-functional acrylic plasticizer is used. Examples of acrylic plasticizers include (meth)acrylate polymers and (meth)acrylate-aromatic vinyl monomer copolymers, with (meth)acrylate polymers being preferred. The acrylic plasticizer preferably contains at least 50% by weight, more preferably at least 70% by weight, of all repeating units derived from (meth)acrylate.

[0091] The (meth)acrylate is not particularly limited. Examples thereof include alkyl acrylates having an alkyl group with 10 or fewer carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; and alkyl methacrylates having an alkyl group with 10 or fewer carbon atoms, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate. These (meth)acrylates may be used alone or in combination of two or more. Among them, one or more selected from methyl methacrylate, butyl methacrylate, ethyl acrylate, and butyl acrylate are preferred.

[0092] The aromatic vinyl monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, and the like.

[0093] The (meth)acrylate polymer includes homopolymers of alkyl acrylates, homopolymers of alkyl methacrylates, copolymers of alkyl acrylates, copolymers of alkyl methacrylates, and copolymers of alkyl acrylates and alkyl methacrylates.

[0094] The acrylic plasticizer (D1) is not particularly limited, but specifically, commercially available non-functional acrylic plasticizers such as "UP-1000," "UP-1010," "UP-1020," "UP-1021," and "UP-1061" manufactured by Toagosei Co., Ltd. can be used.

[0095] Oil-absorbing powder (E)

[0096] The oil-absorbing powder (E) may be any compound having oil-absorbing properties, and any inorganic or organic compound may be used. Specific examples of the oil-absorbing powder (E) include inorganic compounds such as silica (including wet silica), silica diatomaceous earth, perlite, boron nitride, talc (talc), mica, calcium carbonate, graphite (including natural graphite and artificial graphite), and carbon black, and lipophilic treatments of these inorganic compounds. Preferably, the oil-absorbing powder (E) is at least one selected from silica, talc, and mica.

[0097] The oil absorption of the oil-absorbing powder (E) is preferably 5 mL / 100 g or more and 350 mL / 100 g or less, more preferably 10 mL / 100 g or more and 300 mL / 100 g or less, and even more preferably 20 mL / 100 g or more and 250 mL / 100 g or less. When the oil absorption of the oil-absorbing powder (E) is 5 mL / 100 g or more, the fluidity of the mixture of the carrier resin composition (B1) and the thermally expandable microcapsules (A) is easily improved, and the feedability to the extruder is easily improved. When the oil absorption of the oil-absorbing powder (E) is 350 mL / 100 g or less, the fluidity of the mixture of the carrier resin composition (B1) and the thermally expandable microcapsules (A) can be appropriately adjusted, and mass production is improved. In one or more embodiments of the present invention, the oil absorption of the oil-absorbing powder (E) is obtained by measuring the amount of bis(2-ethylhexyl) adipate (DOA) absorbed by the oil-absorbing powder (E) in accordance with JIS K5101-13-1.

[0098] The oil-absorbing powder (E) is not particularly limited. However, from the perspective of suppressing a decrease in the strength of an injection-molded foam molded article using the masterbatch, the average particle size is preferably 0.01 μm to 100 μm, more preferably 0.2 μm to 50 μm, even more preferably 0.5 μm to 40 μm, and particularly preferably 1 μm to 30 μm. In one or more embodiments of the present invention, the average particle size of the oil-absorbing powder (E) can be measured by a conventional static light scattering method (laser diffraction, scattering method) or dynamic light scattering method (photon correlation method) appropriate to the particle size and other properties.

[0099] The carrier resin composition (B1) may further contain a low-molecular-weight styrene-based resin (D2) having a weight-average molecular weight of 1,000 or more and 150,000 or less.

[0100] 《Low molecular weight styrene resin (D2)》

[0101] The weight average molecular weight of the low molecular weight styrene resin (D2) is greater than or equal to 1,000 and less than or equal to 150,000, and is liquid or solid at 20°C. From the viewpoint of excellent handling and easy mixing with other components such as the acrylic resin (C) in the carrier resin composition (B1), the low molecular weight styrene resin (D2) is preferably solid at 20°C. From the viewpoint of reducing the scattering of the mixture containing the carrier resin composition (B1), the heat-expandable microcapsules (A) and the carrier resin composition (B1), the low molecular weight styrene resin (D2) is preferably liquid at 20°C. The low molecular weight styrene resin (D2) may be a homopolymer of a styrene monomer or a copolymer of two or more styrene monomers. In addition, it may be a copolymer of a styrene monomer and other copolymerizable monomers. In this case, the repeating units derived from the styrene monomer may be contained in all the repeating units in an amount of 50% by weight or more, preferably 80% by weight or more.

[0102] Examples of the styrene monomers include styrene and styrene derivatives. Examples of the styrene derivatives include methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene. Among these, styrene is preferred.

[0103] Examples of the above-mentioned other copolymerizable monomers include: polyfunctional vinyl compounds such as divinylbenzene; (meth)acrylic acid compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, and acrylonitrile; diene compounds such as butadiene and their derivatives; and unsaturated carboxylic acid esters such as maleic acid ester and itaconic acid ester. These other copolymerizable monomers may be used alone or in combination of two or more.

[0104] From the viewpoint of processability, the low-molecular-weight styrene-based resin (D2) is preferably a styrene homopolymer.

[0105] From the viewpoint of improving compatibility with polycarbonate resins, the weight average molecular weight of the low molecular weight styrene resin (D2) is preferably 130,000 or less, more preferably 100,000 or less, further preferably 80,000 or less, and particularly preferably 40,000 or less. In addition, from the viewpoint of improving the processability of the masterbatch, the weight average molecular weight of the low molecular weight styrene resin (D2) is preferably 2,000 or more, more preferably 5,000 or more, and further preferably 10,000 or more. Specifically, the weight average molecular weight of the low molecular weight styrene resin (D2) is preferably 2,000 or more and 130,000 or less, more preferably 2,000 or more and 100,000 or less, further preferably 5,000 or more and 80,000 or less, and particularly preferably 5,000 or more and 40,000 or less.

[0106] The low molecular weight styrene resin (D2) is not particularly limited, but preferably has a glass transition temperature of 25°C or higher and 130°C or lower. When the glass transition temperature of the low molecular weight styrene resin (D2) is 25°C or higher, the extruder temperature can be easily controlled during masterbatch production, resulting in improved processability. Furthermore, when the glass transition temperature of the low molecular weight styrene resin (D2) is 130°C or lower, the carrier resin composition tends to have an appropriate viscosity during masterbatch production, thereby preventing the thermally expandable microcapsules (A) from breaking and improving processability.

[0107] In the case where the masterbatch contains a carrier resin composition (B1), the content of the acrylic plasticizer (D1) in the masterbatch is 0.1 wt% or more and 4 wt% or less. The adhesion of the carrier resin composition (B1) is reduced and the fluidity is improved, so the productivity of the masterbatch becomes good. The content of the acrylic plasticizer (D1) in the masterbatch is preferably 3 wt% or less. From the viewpoint of easily obtaining a masterbatch in which the thermally expandable microcapsules (A) are uniformly dispersed in the carrier resin composition (B1), the content of the acrylic plasticizer (D1) in the masterbatch is preferably 0.5 wt% or more, more preferably 0.8 wt% or more. Specifically, the content of the acrylic plasticizer (D1) in the masterbatch is preferably 0.5 wt% or more and 4 wt% or less, more preferably 0.5 wt% or more and 3 wt% or less, further preferably 0.8 wt% or more and 3 wt% or less,

[0108] In addition, when the carrier resin composition (B1) contains a low molecular weight styrene resin (D2), from the viewpoint of handling properties, the content of the low molecular weight styrene resin (D2) in the masterbatch is preferably from 0.1 wt % to 4 wt %, more preferably from 0.5 wt % to 3 wt %.

[0109] In addition, when the carrier resin composition (B1) contains a low molecular weight styrene resin (D2), the total content of the acrylic plasticizer (D1) and the low molecular weight styrene resin (D2) in the masterbatch is preferably 0.1 weight % or more and less than 12 weight %, more preferably 0.5 weight % or more and 8 weight % or less, further preferably 0.5 weight % or more and 6 weight % or less, and particularly preferably 0.8 weight % or more and 4 weight % or less.

[0110] When the masterbatch includes a carrier resin composition (B1), the content of the oil-absorbing powder (E) in the masterbatch is 0.1% by weight or more and less than 4% by weight. This reduces the adhesiveness of the carrier resin composition (B1) or the mixture of the carrier resin composition (B1) and the thermally expandable microcapsules (A) without reducing the processability of the masterbatch, thereby improving the fluidity and thus improving the productivity of the masterbatch. From the perspective of the fluidity of the carrier resin composition (B1) and the processability of the masterbatch, the content of the oil-absorbing powder (E) in the masterbatch is preferably 0.1% by weight or more and 3% by weight or less, more preferably 0.1% by weight or more and 2% by weight or less, and even more preferably 0.1% by weight or more and 1.5% by weight or less.

[0111] <Carrier resin composition (B2)>

[0112] The carrier resin composition (B2) comprises an acrylic resin (C) and a low molecular weight styrene resin (D2). In the masterbatch comprising the heat-expandable microcapsules (A) and the carrier resin composition (B2), the content of the low molecular weight styrene resin (D2) is 0.1% by weight or more and less than 12% by weight, preferably 0.5% by weight or more and 10% by weight or less, more preferably 0.5% by weight or more and 6% by weight or less, and further preferably 0.5% by weight or more and 4% by weight or less. Thus, it is easy to supply the carrier resin composition (B2) or the mixture of the carrier resin composition (B2) and the heat-expandable microcapsules (A) to the extruder, and the ejection amount of the melt-kneaded product can also be increased. As the acrylic resin (C) and the low molecular weight styrene resin (D2), the resins described in the "carrier resin composition (B1)" can be appropriately used. From the viewpoint of excellent handling and easy mixing with other components such as the acrylic resin (C) in the carrier resin composition (B2), the low molecular weight styrene resin (D2) is preferably solid at 20°C. From the viewpoint of reducing scattering of the mixture containing the carrier resin composition (B2), the thermally expandable microcapsules (A), and the carrier resin composition (B2), the low molecular weight styrene resin (D2) is preferably liquid at 20°C. In the present invention, the carrier resin composition (B2) substantially does not contain the acrylic plasticizer (D1) and the oil-absorbing powder (E).

[0113] The carrier resin composition (B2) may contain the oil-absorbing powder (E) within a range where the content of the oil-absorbing powder (E) in the masterbatch is less than 4% by weight. When the masterbatch contains the carrier resin composition (B2), the content of the oil-absorbing powder (E) in the masterbatch is preferably from 0.1% by weight to 3% by weight, more preferably from 0.1% by weight to 2% by weight, even more preferably from 0.1% by weight to 1.5% by weight, and even more preferably from 0.1% by weight to 1% by weight.

[0114] By using the carrier resin composition (B1) or the carrier resin composition (B2) having the above-mentioned structure as the carrier resin composition (B), the carrier resin composition (B) is easily substantially compatible with the polycarbonate resin, and the shear viscosity at 130°C is easily 1.0×10 2 Pa·s or above and 1.0×10 6 Pa·s or less. Therefore, in a foamed resin molded article made from a polycarbonate resin composition using a masterbatch of heat-expandable microcapsules (A) masterbatched with a carrier resin composition (B), whitening is suppressed, resulting in a favorable appearance. In the present invention, "substantially compatible with the polycarbonate resin" specifically means that the glass transition temperature detectable in differential scanning calorimetry (DSC) of a mixture of the carrier resin composition (B) and the polycarbonate resin is the same.

[0115] By making the shear viscosity of the carrier resin composition (B) at 130°C to be 1.0×10 2 Pa·s or above and 1.0×10 6 Pa·s or less, it is easy to obtain a masterbatch in which the heat-expandable microcapsules (A) are uniformly dispersed in the carrier resin composition (B). Specifically, when the heat-expandable microcapsules (A) and the carrier resin composition (B) are kneaded at 130°C to prepare a masterbatch, by adjusting the viscosity of the carrier resin composition (B) to an appropriate range, shearing is not generated in the heat-expandable microcapsules (A), and shear heating can be suppressed. As a result, the heat-expandable microcapsules (A) can be pelletized without expanding. From the perspective of improving the processability of the masterbatch, the shear viscosity of the carrier resin composition (B) at 130°C is preferably 1.0×10 3 Pa·s or above 9.0×10 5 Pa·s or less, more preferably 2.0×10 3 Pa·s or above and 8.0×10 5 Pa·s or less, more preferably 3.0×10 3 Pa·s or above and 3.0×10 5 Pa·s or less, more preferably 5.0×10 3 Pa·s or above and 1.5×10 5Pa·s or less. The shear viscosity of the carrier resin composition (B) at 130°C can be measured using a flow tester (Model CFT-500C) manufactured by Shimadzu Corporation. Specifically, the measurement start temperature is set to 50°C, a load of 30 kgf is applied to the carrier resin composition (B) in a capillary tube with a diameter of 1.0 mm and a length of 10 mm, and the carrier resin composition (B) is flowed. The temperature is increased at a rate of 10°C / min, and the shear viscosity is measured when the measurement temperature reaches 130°C.

[0116] From the viewpoint of improving the low-temperature processability of the masterbatch, the shear viscosity of the carrier resin composition (B) at any temperature within the temperature range of 60°C to 100°C is preferably 1.0×10 2 Pa·s or above and 1.5×10 6 Pa·s or less.

[0117] From the viewpoint of reducing the scattering of the mixture containing the carrier resin composition (B), the heat-expandable microcapsules (A) and the carrier resin composition (B), the carrier resin composition (B) is preferably the carrier resin composition (B1) or a carrier resin composition (B2) containing a low molecular weight styrene-based resin (D2) that is liquid at 20°C, and more preferably the carrier resin composition (B1).

[0118] From the viewpoints of handling properties, storage stability, and dispersibility in the base resin, the masterbatch preferably contains 30% by weight or more and 80% by weight or less of the thermally expandable microcapsules (A), more preferably 30% by weight or more and 70% by weight or less, and even more preferably 30% by weight or more and 60% by weight or less.

[0119] From the viewpoint of compatibility with the polycarbonate resin and processability, the masterbatch preferably contains 20% by weight or more and 70% by weight or less of the carrier resin composition (B), more preferably 30% by weight or more and 70% by weight or less, and even more preferably 40% by weight or more and 70% by weight or less.

[0120] When the masterbatch contains the carrier resin composition (B1), from the viewpoints of compatibility with the polycarbonate resin and shear viscosity at 130° C., as well as handleability, storage stability, and dispersibility in the base resin, it is preferred that the masterbatch contain 30% by weight or more and 80% by weight of the heat-expandable microcapsules (A), 15% by weight or more and 62.5% by weight of the acrylic resin (C), 0.1% by weight or more and 4% by weight of the acrylic plasticizer (D1), and 0.1% by weight or more and 3.5% by weight of the oil-absorbing powder (E). More preferably, the masterbatch contains 31% by weight or more and 80% by weight of the heat-expandable microcapsules (A), 15% by weight or more and 62.5% by weight of the acrylic resin (C), and 0.5% by weight of the acrylic plasticizer (D1). The present invention further preferably contains from 35% to 75% by weight of the heat-expandable microcapsules (A), from 20% to 60% by weight of the acrylic resin (C), from 0.5% to 3% by weight of the acrylic plasticizer (D1), and from 0.1% to 2% by weight of the oil-absorbing powder (E). It further preferably contains from 35.5% to 75% by weight of the heat-expandable microcapsules (A), from 20.5% to 60% by weight of the acrylic resin (C), from 0.5% to 3% by weight of the acrylic plasticizer (D1), and from 0.1% to 1.5% by weight of the oil-absorbing powder (E).

[0121] When the masterbatch contains the carrier resin composition (B1), from the viewpoints of compatibility with the polycarbonate resin, shear viscosity at 130° C., handleability, storage stability, and dispersibility in the base resin, specifically, it is preferred that the masterbatch contains 30% by weight or more and 80% by weight of the heat-expandable microcapsules (A), 15% by weight or more and 58.5% by weight of the acrylic resin (C), 0.1% by weight or more and 4% by weight of the acrylic plasticizer (D1), 0.1% by weight or more and 4% by weight of the low-molecular-weight styrene resin (D2), and 0.1% by weight or more and 3.5% by weight of the oil-absorbing powder (E). More preferably, it contains 33% by weight or more and 80% by weight of the heat-expandable microcapsules (A), 15% by weight or more and 58.5% by weight of the acrylic resin (C), 0.5% by weight or more and 4% by weight of the acrylic plasticizer (D1), and 0.5% by weight or less of the low-molecular-weight styrene resin (D2). The present invention further preferably contains from 34% to 70% by weight of the heat-expandable microcapsules (A), from 22% to 58% by weight of the acrylic resin (C), from 0.5% to 3% by weight of the acrylic plasticizer (D1), from 0.5% to 3% by weight of the low-molecular-weight styrene resin (D2), and from 0.1% to 2% by weight of the oil-absorbing powder (E). It further preferably contains from 34.5% to 70% by weight of the heat-expandable microcapsules (A), from 22.5% to 58% by weight of the acrylic resin (C), from 0.5% to 3% by weight of the acrylic plasticizer (D1), from 0.5% to 3% by weight of the low-molecular-weight styrene resin (D2), and from 0.1% to 2% by weight of the oil-absorbing powder (E).

[0122] When the masterbatch contains the carrier resin composition (B2), from the viewpoints of compatibility with the polycarbonate resin, shear viscosity at 130°C, handleability, storage stability, and dispersibility in the base resin, specifically, it is preferred that the masterbatch contain 30% by weight or more and 75% by weight of the heat-expandable microcapsules (A), 15% by weight or more and 60% by weight of the acrylic resin (C), and 0.1% by weight or more and 10% by weight of the low-molecular-weight styrene resin (D2). It is more preferred that the masterbatch contain 34% by weight or more and 75% by weight of the heat-expandable microcapsules (A), 19% by weight or more and 60% by weight of the acrylic resin (C), and 0.5% by weight or more and 6% by weight of the low-molecular-weight styrene resin (D2). It is even more preferred that the masterbatch contain 36% by weight or more and 75% by weight of the heat-expandable microcapsules (A), 21% by weight or more and 60% by weight of the acrylic resin (C), and 0.5% by weight or more and 4% by weight of the low-molecular-weight styrene resin (D2).

[0123] <Masterbatch Manufacturing Method>

[0124] In one or more embodiments of the present invention, the masterbatch can be produced, for example, by mixing the thermally expandable microcapsules (A) and the carrier resin composition (B), specifically, the carrier resin composition (B1) or the carrier resin composition (B2), supplying the resulting mixture to an extruder, melt-kneading the mixture, and extruding the resulting melt-kneaded product (hereinafter also referred to as Embodiment 1), but is not particularly limited thereto. The extruded strands can be cut into pellets.

[0125] In the first embodiment, the heat-expandable microcapsules (A) and the carrier resin composition (B), specifically, the components constituting the carrier resin composition (B), are not particularly limited. For example, a mixture of the heat-expandable microcapsules (A) and the carrier resin composition (B) can be obtained by mixing them using a high-speed mixer, a Henschel mixer, a floater, or the like.

[0126] In the first embodiment, by using the carrier resin composition (B1) or the carrier resin composition (B2) having the above-mentioned structure as the carrier resin composition (B), the feedability of the mixture of the thermally expandable microcapsules and the carrier resin composition to the extruder is improved, the discharge amount of the melt-kneaded product is increased, and the productivity of the masterbatch is improved.

[0127] In embodiment 1, when the carrier resin composition (B1) is used as the carrier resin composition (B), the mixture of the heat-expandable microcapsule (A) and the carrier resin composition (B1) becomes a mixture of powder and liquid. When the carrier resin composition (B2) is used as the carrier resin composition (B), the mixture of the heat-expandable microcapsule (A) and the carrier resin composition (B2) becomes a mixture of powder and liquid or a powder mixture. When the above-mentioned mixture is put into a twin-screw quantitative feeder, it is preferred that the above-mentioned mixture flows in the feeder by the rotation of the twin screws and is ejected from the feeder. For example, a twin-screw box-type weighing feeder (model: CE-W-0) manufactured by KUOTA Co., Ltd. is used as a twin-screw quantitative feeder. When 1 kg of the mixture is added to the feeder, it is preferred that the mixture flows appropriately in the feeder by the rotation of the twin screws and is ejected from the feeder. By using the carrier resin composition (B1) or the carrier resin composition (B2) as the carrier resin composition (B), the mixture does not adhere to the wall surface inside the feeder, and the rotation of the twin screw allows the mixture to flow appropriately within the feeder, thereby improving the feedability of the raw material to the extruder. From the perspective of preventing the raw material from scattering when feeding the extruder, a mixture of a powder and a liquid obtained by mixing the heat-expandable microcapsule (A) and the carrier resin composition (B1) or a mixture of a powder and a liquid obtained by mixing the heat-expandable microcapsule (A) and the carrier resin composition (B2) containing a low molecular weight styrene-based resin (D2) that is liquid at 20°C is preferred. A mixture of a powder and a liquid obtained by mixing the heat-expandable microcapsule (A) and the carrier resin composition (B1) is more preferred.

[0128] In one or more embodiments of the present invention, the masterbatch can be produced, for example, by supplying heat-expandable microcapsules (A) and a carrier resin composition (B), specifically, a carrier resin composition (B1) or a carrier resin composition (B2), to an extruder, melt-kneading the heat-expandable microcapsules (A) and the carrier resin composition (B), and extruding the resulting melt-kneaded product (hereinafter also referred to as Embodiment 2), without particular limitation. The extruded strands can be cut into pellets.

[0129] In the second embodiment, the carrier resin composition (B), specifically the carrier resin composition (B1) or the carrier resin composition (B2), can be obtained by mixing the components using, for example, a high-speed mixer, a Henschel mixer, a floater, etc., without particular limitation.

[0130] By using the carrier resin composition (B1) or the carrier resin composition (B2) having the above-described structure as the carrier resin composition (B), the supply properties of the carrier resin composition (B) to the extruder are improved, the discharge amount of the melt-kneaded product is increased, and the productivity of the masterbatch is improved.

[0131] During melt kneading, the heat-expandable microcapsules (A) and the carrier resin composition (B) may be supplied to the extruder from the same raw material supply port or from different raw material supply ports. When the heat-expandable microcapsules (A) and the carrier resin composition (B) are supplied to the extruder from different raw material supply ports, the raw material supply port for supplying the carrier resin composition (B) is preferably arranged upstream in the extrusion direction relative to the raw material supply port for supplying the heat-expandable microcapsules (A).

[0132] The extruder for melt mixing is not particularly limited, and can be a single screw extruder or a twin screw extruder. From the viewpoint of versatility and dispersibility, a twin screw extruder is preferably used. In embodiment 1, the above-mentioned mixture is supplied to the extruder from the raw material supply port and melt mixed. In embodiment 2, the heat-expandable microcapsule (A) and the carrier resin composition (B) are supplied to the extruder from the raw material supply port and melt mixed. The melt mixing temperature is not particularly limited, for example, preferably 110°C or more and 150°C or less, more preferably 120°C or more and 140°C or less. In the case of a 25mm extruder, the ejection amount is preferably 3kg / hour or more and 10kg / hour or less, more preferably 3kg / hour or more and 7kg / hour or less.

[0133] <Polycarbonate resin composition>

[0134] A polycarbonate resin composition is a resin composition comprising the aforementioned masterbatch and a polycarbonate resin, with the polycarbonate resin as the main component. Here, "main component" means that the polycarbonate resin comprises the largest proportion of all components in the polycarbonate resin composition. Components other than the masterbatch in the polycarbonate resin composition are also referred to as base components.

[0135] The content of the masterbatch in the polycarbonate resin composition can be appropriately set based on the expansion ratio of the final product, the type of blowing agent, the resin temperature during molding, and other factors. The content of the masterbatch in the polycarbonate resin composition is preferably from 1% by weight to 20% by weight, more preferably from 2% by weight to 15% by weight, and particularly preferably from 3% by weight to 10% by weight. By using the masterbatch within this range, it is easy to obtain an economically sized foamed article having an expansion ratio of 1.1 or more and uniform, fine bubbles.

[0136] The polycarbonate resin is a polycarbonate resin derived from a compound having two phenolic hydroxyl groups (hereinafter referred to as a dihydric phenol), and is generally a resin obtained by the reaction of a dihydric phenol and phosgene, or a dihydric phenol and a carbonic acid diester.

[0137] Examples of the dihydric phenol include bisphenol, methylene bisphenol (bisphenol F), bis(4-hydroxyphenyl)sulfone (bisphenol S), and 2,2-bis(4-hydroxyphenyl)propane (bisphenol A). Among these, bisphenol A is preferred, but the present invention is not limited thereto.

[0138] From the perspectives of impact resistance, chemical resistance, and moldability, the number average molecular weight of the polycarbonate resin is preferably 10,000 or more and 60,000 or less, more preferably 10,000 or more and 30,000 or less. The content of the polycarbonate resin in the polycarbonate resin composition is preferably 30% by weight or more and 99% by weight or less, more preferably 30% by weight or more and 80% by weight or less, and even more preferably 30% by weight or more and 70% by weight or less. In one or more embodiments of the present invention, the number average molecular weight of the resin is measured by GPC (gel permeation chromatography).

[0139] The polycarbonate resin composition may further include one or more other thermoplastic resins selected from polyester resins, polyester-polyether copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-ethylene-propylene-diene-styrene copolymers, acrylate-styrene-acrylonitrile copolymers, acrylonitrile-styrene copolymers, polyarylate resins, and polystyrene resins. There is no particular limitation on the polyester resin, polyester-polyether copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-ethylene-propylene-diene-styrene copolymer, acrylate-styrene-acrylonitrile copolymer, acrylonitrile-styrene copolymer, polyarylate resin, or polystyrene resin, and for example, the substances described in International Publication No. 2019 / 208653 can be appropriately used.

[0140] From the viewpoint of effectively suppressing the whitening of the surface of the injection-molded foaming molded body and making the appearance better, the polycarbonate resin composition preferably contains 1% by weight or more and 15% by weight of a masterbatch, 30% by weight or more and 99% by weight of a polycarbonate resin, and 0% by weight or more and 55% by weight of one or more thermoplastic resins selected from polyester resins, polyester-polyether copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-ethylene-propylene-diene-styrene copolymers, acrylate-styrene-acrylonitrile copolymers, acrylonitrile-styrene copolymers, polyarylate resins, and polystyrene resins.

[0141] In order to improve the flexural rigidity and dimensional stability of the injection molded foaming body, the above-mentioned polycarbonate resin composition can further include an inorganic compound. As a compound, one or more of mica, talc, montmorillonite, sericite, kaolin, glass flake, plate-like alumina, synthetic hydrotalcite, wollastonite, hollow glass beads, carbon fiber, aramid fiber and whisker can be enumerated. From the viewpoint of flexural rigidity improvement effect and the dispersibility of polycarbonate resin, it is more preferably selected from mica, talc, montmorillonite, sericite, kaolin, glass flake, hollow glass beads and carbon fiber. From the viewpoint of the balance of impact resistance, fluidity and product appearance, it is more preferably selected from mica, talc, glass flake and wollastonite.

[0142] From the viewpoints of impact resistance, heat resistance, rigidity and formability, the polycarbonate resin composition preferably contains 5% by weight or more and 45% by weight or less of inorganic compounds, more preferably 5% by weight or more and 35% by weight or less, and even more preferably 5% by weight or more and 25% by weight or less.

[0143] In order to further improve the impact resistance of the injection foaming molded body, the polycarbonate resin composition may further contain an impact resistance modifier. As the impact resistance modifier, it is preferably selected from one or more of a multi-stage graft polymer, a polyolefin polymer, an olefin-unsaturated carboxylic acid ester copolymer, and a thermoplastic polyester elastomer.

[0144] The amount of the impact modifier is preferably 0 to 20 wt %, more preferably 0 to 15 wt %, and even more preferably 0 to 10 wt % in the polycarbonate resin composition from the viewpoints of impact resistance, heat resistance, rigidity, and moldability.

[0145] The polycarbonate resin composition may contain additives such as flame retardants, UV resistant agents, stabilizers, release agents, pigments, softeners, plasticizers, and surfactants as needed. The amount of these additives in the polycarbonate resin composition is preferably from 0.01% to 6% by weight, and more preferably from 0.1% to 4% by weight.

[0146] <Injection foam molding>

[0147] By injection molding and foaming the above-mentioned polycarbonate resin composition, an injection molded foaming molded body with suppressed whitening and good appearance is obtained. Specifically, the above-mentioned injection molded foaming molded body can be produced by a method of foaming the above-mentioned polycarbonate resin composition in a mold. As a method for foaming it in a mold, there is no particular limitation, and examples thereof include: a core-retracting method, a short injection method, a full fill method, etc. Among them, it is preferred to use a mold consisting of a fixed mold (also called a cavity) and a movable mold (also called a core) that can advance and retreat to any position, and after the resin composition is injection molded to an initial filling thickness, the movable mold is retreated and foamed, so-called core-retracting method (Moving Cavity method). According to the core-retracting method, by forming a non-foaming layer on the surface, the surface unevenness of the order of several μm to tens of μm is smoothed, and the internal foaming layer is easy to become uniform fine bubbles, and it is easy to obtain an injection molded foaming molded body with excellent lightness, so it is preferred.

[0148] In the core-retraction method, the retreat of the movable mold can be performed in one step or in multiple steps of two or more, and the retreat speed can also be adjusted appropriately. For example, it is preferable to include: a process of injection filling a mold composed of a fixed mold and a movable mold that can advance and retreat to any position, and an initial mold cavity gap t0 (initial filling thickness) of 1.5 mm or more and 2.7 mm or less; and a process of injection filling to the initial filling thickness so that the mold cavity gap t f A step of retracting the movable mold and performing foaming so as to achieve a thickness of 2.0 mm to 6.0 mm.

[0149] In the core-back method, other molding conditions may include a resin temperature of 240°C to 280°C, a mold temperature of 60°C to 90°C, a molding cycle of 1 second to 60 seconds, an injection speed of 10 mm / s to 400 mm / s, an injection pressure of 10 MPa to 200 MPa, a back pressure of 5 MPa to 40 MPa, and a screw speed of 10 rpm to 200 rpm.

[0150] The above-mentioned injection-molded foamed article is not particularly limited, and can be appropriately used for, for example, electrical products such as mobile phones and computer cases, vehicle exterior decorative material components such as license plate decorations, pillar decorations, rail covers, roof panels and spoilers, vehicle exterior panel components such as fenders, door panels, rear door panels, roofs, fuel tank caps, trunk lids, retractable headlight panels, control boxes for industrial robots / cranes, control boxes and housings for game consoles, frames, covers and housings for VR / AR goggles, exterior panels for drones, and the like.

[0151] From the viewpoint of lightweight and impact strength of the molded body, the specific gravity of the injection foam molded body is preferably 0.3 g / cm 3Above and 1.2g / cm 3 The specific gravity of the injection molded foam is less than 0.3g / cm 3 When the diameter of the foam is larger than 1.5 mm, the impact strength tends to decrease. When the diameter is larger than 1.2 g / cm 3 , it is difficult to achieve lightweight. The specific gravity can be calculated based on JISK 7112: 1999 and by the water substitution method. From the viewpoint of lightweight and impact strength, the foaming ratio of the injection molded foaming body is preferably 1.1 times or more and 3.0 times or less, more preferably 1.1 times or more and 2.5 times or less, and further preferably 1.1 times or more and 2.0 times or less. When the foaming ratio is less than 1.1 times, there is a tendency that it is difficult to obtain lightweight, and when it exceeds 3.0 times, there is a tendency that the reduction in surface impact strength becomes significant. It should be noted that, in this specification, the foaming ratio refers to the thickness of the injection molded foaming body (the cavity gap t after core pulling) f ) divided by the initial cavity gap t0.

[0152] Example

[0153] Hereinafter, the present invention will be described based on specific examples and comparative examples, but the present invention is not limited to the following examples. Hereinafter, unless otherwise specified, "parts" means parts by weight, and "%" means % by weight.

[0154] Various measurement methods and evaluation methods are shown below.

[0155] (1) Glass transition temperature

[0156] The glass transition temperature was measured using a differential scanning calorimeter (DSC220C manufactured by Seiko Instruments Inc.) under the condition of a temperature increase of 5° C. / min.

[0157] (2) Weight average molecular weight

[0158] The weight average molecular weight of the resin was measured by GPC (gel permeation chromatography). Specifically, the value was determined by measuring using a system: Tosoh HLC-8220, a column: Tosoh TSKgel SuperHZM-H (×2), and a solvent: THF, and calculated by polystyrene conversion.

[0159] (3) Average particle size

[0160] The average particle size of the heat-expandable microcapsules (unexpanded) and the average particle size of the oil-absorbing powder were measured using a laser diffraction particle size distribution analyzer SALD-3000J manufactured by Shimadzu Corporation.

[0161] (4) Oil absorption

[0162] The oil absorption of the oil-absorbing powder is determined by measuring the amount of bis(2-ethylhexyl) adipate (DOA) absorbed by the oil-absorbing powder in accordance with JIS K5101-13-1.

[0163] (5) Viscosity

[0164] The viscosity of the acrylic plasticizer at 25° C. is measured using an E-type viscometer based on JIS Z 8803-1991.

[0165] (6) Maximum expansion temperature

[0166] TMA measurements were performed using a TMA-7 manufactured by PerkinElmer. Approximately 0.25 mg of a heat-expandable microcapsule sample was placed in a container, and the temperature was raised at a rate of 5°C / min. The height displacement was continuously measured, and the temperature at which the height displacement of the sample within the container reached its maximum was defined as the maximum expansion temperature.

[0167] (7) Shear viscosity

[0168] The shear viscosity of the carrier resin composition (B) at 80°C or 130°C was measured using a flow tester "Type CFT-500C" manufactured by Shimadzu Corporation. Specifically, the measurement start temperature was set to 50°C, a constant load of 30 kgf was applied to the carrier resin composition (B) in a capillary tube with a diameter of 1.0 mm and a length of 10 mm, and the composition was flowed. The temperature was increased at a rate of 10°C / min, and the shear viscosity was measured when the measurement temperature reached 80°C or 130°C.

[0169] (8) Raw material availability

[0170] 1 kg of a mixture of the thermally expandable microcapsules (A) and the carrier resin composition (B) was fed into a twin-screw quantitative feeder for an extruder (manufactured by KUOTA Co., Ltd., twin-screw box-type weigh feeder, model: CE-W-0). It was confirmed whether the mixture could be fed into the extruder solely by the rotation of the twin screws located at the bottom of the feeder and by their own weight, even without a stirring blade inside the feeder. The raw material supply performance was evaluated according to the following criteria.

[0171] Good: The mixture can be fed into the extruder by its own weight

[0172] Defective: The mixture cannot be fed into the extruder by its own weight.

[0173] (9) Raw material scattering

[0174] The hopper part of a twin-screw quantitative feeder for an extruder (KUOTA Co., Ltd., twin-screw box-type weighing feeder, model: CE-W-0) was used, as shown in FIG. Figure 1 and Figure 2 As shown, a gap 3 was provided at the joint of components 1 and 2 so that the interval La became 0.5 mm. A mixture of heat-expandable microcapsules (A) and a carrier resin composition (B) was introduced from the upper portion of component 1 to the joint of components 1 and 2. Component 1 was opened, and the scattering state of the raw materials (mixture) was evaluated at the joint surface 4 of component 2 according to the following four-level criteria. Figure 1 In the example, Lb is 30 mm.

[0175] 4: No scattering into the gap

[0176] 3: There is a small amount of scattering in the gap (scattering on the joint surface <15mm)

[0177] 2: Although some amount of scattering occurs in the gap, mass production is possible (scattering on the joint surface <25mm)

[0178] 1: A large amount of scattering into the gap obviously poses a big problem in mass production (scattering ≥ 25mm on the joint surface)

[0179] (10) Amount of melted mixture ejected

[0180] Evaluation was performed according to the following criteria based on the discharge amount of the melt-kneaded product from the extruder die.

[0181] Good: The discharge rate of the molten kneaded material is 3 kg / hour or more

[0182] Bad: The discharge rate of the molten kneaded material is less than 3 kg / hour

[0183] (11) Can it be masterbatch

[0184] The cross section of the masterbatch pellets was observed using a scanning electron microscope (SEM, manufactured by JEOL Ltd., model "JSM-6060LA"), and the processability of the masterbatch was evaluated based on the state of the thermally expandable microcapsules.

[0185] Masterbatch capable: No expansion of heat-expandable microcapsules and no fuzzing of particles

[0186] Unable to masterbatch: No expansion of heat-expandable microcapsules, but pellets become fluffy

[0187] (12) Compatibility with polycarbonate resin (PC)

[0188] Differential scanning calorimetry (DSC) was performed on the mixture of the carrier resin composition (B) and the polycarbonate resin, and compatibility with PC was determined according to the following criteria.

[0189] Compatible: In DSC, the glass transition temperature is

[0190] No compatibility: In DSC, the glass transition temperature is two

[0191] <Production Example 1 of Acrylic Resin (C)>

[0192] <Preparation of Acrylic Resin Particles (a)>

[0193] A reactor equipped with a stirrer was charged with 220 parts of deionized water and 15 parts of a 3% aqueous PVA solution (GH-20, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and the atmosphere inside the reactor was purged with nitrogen. A monomer mixture of 25 parts of butyl acrylate and 75 parts of methyl methacrylate, in which 0.5 parts of lauroyl peroxide, 0.5 parts of benzoyl peroxide, and 0.5 parts of 2-ethylhexyl thioglycolate were dissolved, was added. The stirrer speed was adjusted to achieve a dispersed particle size of approximately 250 μm. The temperature was then raised stepwise to 60°C for 2 hours, 70°C for 2 hours, 80°C for 2 hours, and 90°C for 1 hour to complete polymerization. This produced a suspension of acrylic resin particles (a) having a polymer solids content of 30%, a glass transition temperature of 72°C, and an average particle size of 150 μm.

[0194] <Preparation of Acrylic Resin Particles (b)>

[0195] 220 parts of deionized water, 0.3 parts of boric acid, 0.03 parts of sodium carbonate, 0.09 parts of sodium N-lauroyl sarcosinate, 0.09 parts of sodium formaldehyde sulfoxylate, 0.006 parts of sodium ethylenediaminetetraacetate, and 0.002 parts of ferrous sulfate heptahydrate were added to a reactor with a stirrer, and after nitrogen replacement, the temperature was raised to 80°C, and 25% of a monomer mixture containing 25 parts of methyl methacrylate, 0.1 parts of allyl methacrylate, and 0.1 parts of tert-butyl hydroperoxide was added thereto, and polymerization was carried out for 45 minutes. Then, the remaining 75% of the mixed solution was continuously added over 1 hour. After the addition was completed, the temperature was maintained for 2 hours to complete the polymerization. In addition, 0.2 parts of sodium N-lauroyl sarcosinate were added during this period. The average particle size of the polymer particles of the innermost cross-linked methacrylic polymer obtained in the latex is (Calculated by light scattering at a wavelength of 546 nm), the polymerization conversion rate (polymer production / monomer injection amount × 100) is 98%. Next, the obtained innermost cross-linked methacrylic acid polymer latex is maintained at 80°C in a nitrogen gas stream, and after adding 0.1 parts of potassium persulfate, a monomer mixture of 41 parts of n-butyl acrylate, 9 parts of styrene, and 1 part of allyl methacrylate is continuously added over 5 hours. During this period, 0.1 parts of potassium oleate are added in 3 times. After the addition of the monomer mixture is completed, 0.05 parts of potassium persulfate are further added to terminate the polymerization and maintained for 2 hours. In the obtained emulsion polymerized latex, the average particle size of the latex particles (b1) is The polymerization conversion rate was 99%. Next, the latex of latex particles (b1) was maintained at 80°C, 0.02 parts of potassium persulfate was added, and then a mixture of 24 parts of methyl methacrylate, 1 part of n-butyl acrylate, and 0.1 parts of tert-dodecylmercaptan was continuously added over 1 hour. After the addition of the monomer mixture was completed, the mixture was maintained for 1 hour to obtain a latex of an emulsion-polymerized graft copolymer (acrylic resin particles (b)) having a multilayer structure, an average particle size of 0.25 μm, and a Vicat softening temperature of 90°C.

[0196] <Production of acrylic resin (C)>

[0197] 96 parts of the resulting latex of acrylic resin particles (b) (30 parts solid content, i.e., acrylic resin particles (b)) and 332 parts of a suspension of acrylic resin particles (a) (100 parts solid content, i.e., acrylic resin particles (a)) were mixed under stirring. The resulting mixed suspension (the total solid content, i.e., acrylic resin particles (a) and acrylic resin particles (b) concentration was 30%) was adjusted to 60°C, and 50 parts of a 1.0% aqueous calcium chloride solution was added dropwise over 10 minutes under stirring. The mixture was then heated to 95°C under stirring for heat treatment, yielding an acrylic resin (C) having an average particle size of 200 μm. The acrylic resin (C) had a weight-average molecular weight of 60,000 and a glass transition temperature (Tg) of 77°C.

[0198] (Example 1)

[0199] The acrylic resin (C) obtained above, acrylic plasticizer (D1) (manufactured by Toagosei Co., Ltd., “allfone UP1020”, weight average molecular weight 2000, liquid at 20°C, viscosity 500 mPa·s at 25°C, all acrylic acid, no functional group), oil-absorbing powder (E) (silica particles, wet silica, average particle size 11.5 μm, oil absorption 225 mL / 100 g, manufactured by Evonik Japan Co., Ltd., product name “Carplex”, model “#67”), and thermally expandable microcapsules (A) (manufactured by KUREHA Co., Ltd., “Microsphere The obtained mixture was fed to a co-rotating intermeshing twin-screw extruder (manufactured by TECHNOVEL, 25 mm extruder) via a gravimetric feeder and melt-kneaded at 130° C. The strands were water-cooled and then cut with a pelletizer to obtain a masterbatch of granular thermally expandable microcapsules.

[0200] (Examples 2 to 4)

[0201] A masterbatch was prepared in the same manner as in Example 1, except that the mixing ratio of the acrylic plasticizer (D1) was changed to the mixing ratio shown in Table 1 below, and a low molecular weight styrene resin (D2) (styrene homopolymer, weight average molecular weight 2500, solid at 20°C, glass transition temperature 50°C, "Regit S-94" manufactured by Sanyo Chemical Industries, Ltd.) was further added to the mixing ratio shown in Table 1 below.

[0202] (Example 5)

[0203] A masterbatch was prepared in the same manner as in Example 1, except that the acrylic plasticizer (D1) and the oil-absorbing powder (E) were not used, the mixing ratio of the acrylic resin (C) was changed to the mixing ratio shown in Table 1 below, and the low-molecular-weight styrene resin (D2) was added to the mixing ratio shown in Table 1 below.

[0204] (Comparative Example 1)

[0205] A masterbatch was prepared in the same manner as in Example 1 except that the oil-absorbing powder (E) was not used and the mixing ratio of the acrylic resin (C) and the acrylic plasticizer (D1) was changed to the mixing ratio shown in Table 2 below.

[0206] (Comparative Example 2)

[0207] A masterbatch was prepared in the same manner as in Example 1 except that the mixing ratio of the acrylic resin (C), the acrylic plasticizer (D1), and the oil-absorbing powder (E) was changed to the mixing ratio shown in Table 2 below.

[0208] (Comparative Examples 3 to 6)

[0209] A masterbatch was prepared in the same manner as in Example 2 except that the mixing ratios of the acrylic resin (C), acrylic plasticizer (D1), low molecular weight styrene resin (D2) and oil-absorbing powder (E) were changed to those shown in Table 2 below.

[0210] (Comparative Example 7)

[0211] A masterbatch was prepared in the same manner as in Example 5 except that the mixing ratios of the acrylic resin (C), the low molecular weight styrene resin (D2), and the oil-absorbing powder (E) were changed to those shown in Table 2 below.

[0212] In the Examples and Comparative Examples, the raw material supplyability, the discharge amount of the melt-kneaded product, and the processability of the masterbatch were evaluated as described above, and the results are shown in Tables 1 and 2 below. In addition, in the Examples and Comparative Examples, the shear viscosity of the carrier resin composition (B) at 80°C and 130°C was measured as described above, and the results are shown in Tables 1 and 2 below.

[0213] [Table 1]

[0214]

[0215] [Table 2]

[0216]

[0217] As shown in Table 1, in the examples using carrier resin composition (B1) or carrier resin composition (B2) as carrier resin composition (B), the feedability of the mixture of thermally expandable microcapsules and the carrier resin composition into the extruder was good, the discharge rate of the melt-kneaded product was high, and a masterbatch could be obtained with good productivity. Furthermore, a comparison between Examples 1 to 4 and Example 5 shows that when carrier resin composition (B1) was used as carrier resin composition (B), scattering of the raw materials was suppressed, resulting in excellent mass productivity.

[0218] On the other hand, as shown in Table 2, in Comparative Example 1, which used a carrier resin composition containing an acrylic plasticizer (D1) but not an oil-absorbing powder (E), the feedability of the mixture of the thermally expandable microcapsules and the carrier resin composition into the extruder was poor, and the discharge rate of the melt-kneaded product was also low. Furthermore, in Comparative Examples 2 to 7, which used carrier resin compositions containing an oil-absorbing powder (E), but in which the content of the oil-absorbing powder (E) in the masterbatch was 4% by weight or greater, no masterbatch could be obtained. In Comparative Examples 2 to 7, however, severe fuzzing and poor kneading prevented pellet processing for measurement, and therefore the shear viscosity of the carrier resin composition (B) at 80°C could not be measured.

[0219] The present invention is not particularly limited, and includes, for example, the following aspects.

[0220] [1] A masterbatch comprising a thermally expandable microcapsule (A) and a carrier resin composition (B),

[0221] The carrier resin composition (B) is the carrier resin composition (B1) or the carrier resin composition (B2),

[0222] The carrier resin composition (B1) comprises an acrylic resin (C) having a weight average molecular weight of 8,000 to 350,000 and being solid at 20°C, an acrylic plasticizer (D1) having a weight average molecular weight of 1,000 to 20,000 and being liquid at 20°C, and an oil-absorbing powder (E).

[0223] The carrier resin composition (B2) comprises an acrylic resin (C) having a weight average molecular weight of 8,000 to 350,000, which is solid at 20°C, and a low molecular weight styrene resin (D2) having a weight average molecular weight of 1,000 to 150,000, which is liquid or solid at 20°C.

[0224] When the carrier resin composition (B) is the carrier resin composition (B1), in the masterbatch, the content of the acrylic plasticizer (D1) is 0.1% by weight or more and 4% by weight or less, and the content of the oil-absorbing powder (E) is 0.1% by weight or more and less than 4% by weight,

[0225] When the carrier resin composition (B) is the carrier resin composition (B2), the content of the low-molecular-weight styrene-based resin (D2) in the masterbatch is 0.1% by weight or more and less than 12% by weight.

[0226] [2] The masterbatch according to [1], wherein

[0227] The glass transition temperature of the low molecular weight styrene resin (D2) is 25° C. or higher and 130° C. or lower.

[0228] [3] The masterbatch according to [1] or [2], wherein

[0229] The oil-absorbing powder (E) is at least one selected from the group consisting of silica, silica diatomaceous earth, perlite, boron nitride, talc, mica, calcium carbonate, graphite, and carbon black.

[0230] [4] The masterbatch according to any one of [1] to [3], wherein

[0231] The oil absorption of the oil-absorbing powder (E) is 5 mL / 100 g or more and 350 mL / 100 g or less.

[0232] [5] The masterbatch according to any one of [1] to [4], wherein

[0233] The average particle size of the oil-absorbing powder (E) is 0.01 μm or more and 100 μm or less.

[0234] [6] The masterbatch according to any one of [1] to [5], wherein

[0235] The carrier resin composition (B1) further contains a low molecular weight styrene resin (D2), and the content of the low molecular weight styrene resin (D2) in the masterbatch is 0.1% by weight or more and 4% by weight or less.

[0236] [7] The masterbatch according to any one of [1] to [6], wherein

[0237] The carrier resin composition (B) is compatible with the polycarbonate-based resin.

[0238] [8] The masterbatch according to any one of [1] to [7], wherein

[0239] The heat-expandable microcapsule (A) has a core-shell structure and is composed of a core and a shell surrounding the core, wherein the core is composed of one or more compounds having a boiling point of 10° C. to 330° C.

[0240] The shell is composed of a resin having structural units derived from the following monomers:

[0241] The monomer is one or more selected from nitrile monomers, (meth)acrylate monomers, aromatic vinyl monomers, diene monomers, vinyl monomers having a carboxyl group, and monomers having one or more reactive functional groups selected from methylol, hydroxyl, amino, epoxy and isocyanate groups.

[0242] [9] The masterbatch according to any one of [1] to [8], wherein

[0243] The maximum expansion temperature of the heat-expandable microcapsule (A) is 210° C. or higher and 270° C. or lower.

[0244]

[10] The masterbatch according to any one of [1] to [9], wherein

[0245] The shear viscosity of the carrier resin composition (B) at 130°C was 1.0×10 2 Pa·s or above and 1.0×10 6 Below Pa.

[0246]

[11] The masterbatch according to any one of [1] to

[10] , wherein

[0247] The masterbatch contains 30% by weight or more and 80% by weight or less of the thermally expandable microcapsules (A) and 20% by weight or more and 70% by weight or less of the carrier resin composition (B1) or the carrier resin composition (B2).

[0248]

[12] The method for producing a masterbatch according to any one of [1] to

[11] , comprising:

[0249] a step of mixing the heat-expandable microcapsule (A) and the carrier resin composition (B);

[0250] a step of supplying the obtained mixture to an extruder and performing melt kneading; and

[0251] The step of extruding the obtained melt-kneaded product.

[0252]

[13] The method for producing a masterbatch according to any one of [1] to

[11] , comprising:

[0253] The heat-expandable microcapsule (A) and the carrier resin composition (B) are supplied to an extruder respectively, and the heat-expandable microcapsule (A) and the carrier resin composition (B) are melt-kneaded; and

[0254] The step of extruding the obtained melt-kneaded product.

[0255]

[14] A mixture comprising a heat-expandable microcapsule (A) and a carrier resin composition (B),

[0256] The heat-expandable microcapsule (A) and the carrier resin composition (B) are the heat-expandable microcapsule (A) and the carrier resin composition (B) described in any one of [1] to

[11] , respectively.

[0257] When the carrier resin composition (B) is the carrier resin composition (B1), the mixture is a mixture of powder and liquid. When the carrier resin composition (B) is the carrier resin composition (B2), the mixture is a mixture of powder and liquid or a mixture of powders.

[0258] When the mixture is fed into a twin-screw quantitative feeder, the mixture flows in the feeder due to the rotation of the twin screws and is ejected from the feeder.

[0259]

[15] A polycarbonate resin composition comprising the masterbatch according to any one of [1] to

[11] and a polycarbonate resin.

[0260]

[16] The polycarbonate resin composition according to

[15] , wherein

[0261] The content of the masterbatch in the polycarbonate resin composition is 1% by weight or more and 20% by weight or less.

[0262]

[17] The polycarbonate resin composition according to

[15] or

[16] , wherein

[0263] The polycarbonate resin composition further comprises one or more other thermoplastic resins selected from polyester resins, polyester-polyether copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-ethylene-propylene-diene-styrene copolymers, acrylate-styrene-acrylonitrile copolymers, acrylonitrile-styrene copolymers, polyarylate resins, and polystyrene resins.

[0264]

[18] An injection foam molded product obtained by injection foam molding the polycarbonate resin composition according to any one of

[15] to

[17] .

[0265]

[19] The injection molded article according to

[18] , wherein

[0266] The injection-molded foamed article is an electrical product, a vehicle component, a vehicle exterior material, or a vehicle outer panel.

[0267]

[20] The injection molded article according to

[18] or

[19] , wherein

[0268] The expansion ratio of the injection-molded foam article is 1.1 times or more and 3.0 times or less.

[0269]

[21] A method for producing an injection-molded foamed article, the method comprising: subjecting the polycarbonate resin composition described in any one of

[15] to

[17] to injection-molding foam.

[0270]

[22] The method for producing an injection molded article according to

[21] , wherein:

[0271] The injection foam molding is at least one method selected from the group consisting of a core back method, an undershot method, and a full fill method.

Claims

1. A masterbatch comprising a thermally expandable microcapsule (A) and a carrier resin composition (B), The carrier resin composition (B) is the carrier resin composition (B1) or the carrier resin composition (B2), The carrier resin composition (B1) comprises: an acrylic resin (C) having a weight average molecular weight of 8,000 to 350,000 and being solid at 20°C; an acrylic plasticizer (D1) having a weight average molecular weight of 1,000 to 20,000 and being liquid at 20°C; and an oil-absorbing powder (E). The carrier resin composition (B2) comprises: an acrylic resin (C) having a weight average molecular weight of 8,000 to 350,000 inclusive and being solid at 20° C.; and a low molecular weight styrene resin (D2) having a weight average molecular weight of 1,000 to 150,000 inclusive and being liquid or solid at 20° C. When the carrier resin composition (B) is the carrier resin composition (B1), in the masterbatch, the content of the acrylic plasticizer (D1) is 0.1% by weight or more and 4% by weight or less, and the content of the oil-absorbing powder (E) is 0.1% by weight or more and less than 4% by weight, When the carrier resin composition (B) is the carrier resin composition (B2), the content of the low-molecular-weight styrene-based resin (D2) in the masterbatch is 0.1% by weight or more and less than 12% by weight.

2. The masterbatch according to claim 1, wherein The glass transition temperature of the low molecular weight styrene resin (D2) is 25° C. or higher and 130° C. or lower.

3. The masterbatch according to claim 1 or 2, wherein The oil-absorbing powder (E) is at least one selected from the group consisting of silica, silica diatomaceous earth, perlite, boron nitride, talc, mica, calcium carbonate, graphite, and carbon black.

4. The masterbatch according to claim 1 or 2, wherein The oil absorption of the oil-absorbing powder (E) is 5 mL / 100 g or more and 350 mL / 100 g or less.

5. The masterbatch according to claim 1 or 2, wherein The average particle size of the oil-absorbing powder (E) is 0.01 μm or more and 100 μm or less.

6. The masterbatch according to claim 1 or 2, wherein The carrier resin composition (B1) further comprises a low molecular weight styrene resin (D2), In the masterbatch, the content of the low-molecular-weight styrene-based resin (D2) is 0.1% by weight or more and 4% by weight or less.

7. The masterbatch according to claim 1 or 2, wherein The carrier resin composition (B) is compatible with the polycarbonate-based resin.

8. The masterbatch according to claim 1 or 2, wherein The heat-expandable microcapsule (A) has a core-shell structure and is composed of a core and a shell surrounding the core, wherein the core is composed of one or more compounds having a boiling point of 10° C. or higher and 330° C. or lower. The shell is composed of a resin having structural units derived from the following monomers: The monomer is one or more selected from nitrile monomers, (meth)acrylate monomers, aromatic vinyl monomers, diene monomers, vinyl monomers having a carboxyl group, and monomers having one or more reactive functional groups selected from methylol, hydroxyl, amino, epoxy and isocyanate groups.

9. The masterbatch according to claim 1 or 2, wherein The maximum expansion temperature of the heat-expandable microcapsule (A) is 210° C. or higher and 270° C. or lower.

10. The masterbatch according to claim 1 or 2, wherein The shear viscosity of the carrier resin composition (B) at 130°C was 1.0×10 2 Pa·s or above and 1.0×10 6 Pa·s or less.

11. The masterbatch according to claim 1 or 2, wherein The masterbatch contains 30% by weight or more and 80% by weight or less of the thermally expandable microcapsule (A) and 20% by weight or more and 70% by weight or less of the carrier resin composition (B1) or the carrier resin composition (B2).

12. The method for producing a masterbatch according to any one of claims 1 to 11, comprising: a step of mixing the heat-expandable microcapsule (A) and the carrier resin composition (B); a step of supplying the obtained mixture to an extruder and performing melt kneading; and The step of extruding the obtained melt-kneaded product.

13. The method for producing a masterbatch according to any one of claims 1 to 11, comprising: The heat-expandable microcapsule (A) and the carrier resin composition (B) are supplied to an extruder respectively, and the heat-expandable microcapsule (A) and the carrier resin composition (B) are melt-kneaded; and The step of extruding the obtained melt-kneaded product.

14. A mixture comprising a heat-expandable microcapsule (A) and a carrier resin composition (B), The heat-expandable microcapsule (A) and the carrier resin composition (B) are the heat-expandable microcapsule (A) and the carrier resin composition (B) according to any one of claims 1 to 9, respectively. When the carrier resin composition (B) is the carrier resin composition (B1), the mixture is a mixture of powder and liquid; when the carrier resin composition (B) is the carrier resin composition (B2), the mixture is a mixture of powder and liquid, or a mixture of powders. When the mixture is fed into a twin-screw quantitative feeder, the rotation of the twin screws causes the mixture to flow in the feeder and be ejected from the feeder. 15 . A polycarbonate-based resin composition comprising the masterbatch according to claim 1 and a polycarbonate-based resin.

16. The polycarbonate resin composition according to claim 15, wherein The masterbatch content in the polycarbonate resin composition is 1% by weight or more and 20% by weight or less.

17. The polycarbonate resin composition according to claim 15 or 16, wherein The polycarbonate resin composition further comprises one or more other thermoplastic resins selected from the following group: Polyester resins, polyester-polyether copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-ethylene-propylene-diene-styrene copolymers, acrylate-styrene-acrylonitrile copolymers, acrylonitrile-styrene copolymers, polyarylate resins, and polystyrene resins. 18 . An injection foam molded article obtained by injection foam molding the polycarbonate resin composition according to claim 15 .

19. The injection molded article according to claim 18, wherein The injection-molded foamed article is an electrical product, a vehicle component, a vehicle exterior material, or a vehicle outer panel.

20. The injection molded article according to claim 18 or 19, wherein The expansion ratio of the injection-molded foam article is 1.1 times or more and 3.0 times or less.

21. A method for manufacturing an injection-molded foaming molded body, the method comprising: The polycarbonate resin composition according to any one of claims 15 to 17 is subjected to injection foam molding.

22. The method for producing an injection molded article according to claim 21, wherein: The injection foam molding is one or more methods selected from the group consisting of a core-retraction method, an undershot method, and a full-fill method.

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