Foamed molded body and method for manufacturing a foamed molded body

Abstract

To provide a molding which has an isolated cell and excellent moldability, and is lightweight, and a method for manufacturing the molding.SOLUTION: There is provided a molding in which cells are dispersed in a base material resin containing an elastomer resin, wherein an average circularity of the cells is 0.5-0.9. Standard deviation of circularity distribution of the cells is preferably 0.05-0.15. The cells contain hollow particles, and the hollow particles are preferably particles having an outer shell part containing a thermoplastic resin, and a hollow part surrounded by the outer shell part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a foamed molded article and a method for producing a foamed molded article. [Background technology]

[0002] Various methods have been investigated for obtaining foamed molded articles by adding foaming agents to thermoplastic resins and thermoplastic elastomers. Commonly used foaming molding methods include chemical foaming, in which a chemical foaming agent is mixed with a matrix resin (resin component), and the chemical foaming agent decomposes due to the heat generated when the resin melts, causing foaming with the resulting gas; and physical foaming, in which gases such as water vapor, nitrogen gas, or carbon dioxide (physical foaming agents) are introduced into the molten matrix resin to cause foaming. However, in these methods, the gas easily escapes to the outside of the resin, making it easy for interconnected bubbles to form, which degrades the appearance of the resulting molded article. Furthermore, because the cells become non-uniform, it is difficult to obtain a foamed molded article with uniform and fine cells. In addition, the foaming mechanism in these methods requires control of the melt tension and pressure of the resin, which limits the types of resins and molding conditions under which foamed molded articles can be obtained.

[0003] Therefore, in recent years, a method has been proposed to obtain a foamed molded article having uniform, fine, and closed cells by using thermally expandable microspheres, which have a structure in which a thermoplastic resin is used as the outer shell and an expander is sealed inside, as the foaming agent (see Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2000-17140 [Patent Document 2] Japanese Patent Application Publication No. 11-043551 [Patent Document 3] Japanese Patent Publication No. 2001-97594 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in conventional foam molding using thermally expandable microspheres as a foaming agent, while it is possible to introduce closed cells into the molded body, the processability is poor, making it difficult to produce processed products with complex shapes. Therefore, an investigation into the cause of this decrease in processability revealed that the high sphericity of the cells in the molded body was the reason for the reduced processability. The object of the present invention is to provide a molded article having closed cells and high moldability, and a method for manufacturing the same. [Means for solving the problem]

[0006] The present inventors conducted diligent research to solve the above problems and found that the above problems can be solved by providing a molded article in which cells are dispersed in a specific base resin, and in which the average circularity of the cells is within a specific range, thus arriving at the present invention.

[0007] In other words, the present invention relates to a molded article in which cells are dispersed in a base resin containing an elastomer resin, wherein the average circularity of the cells is 0.5 to 0.9.

[0008] Preferably, the molded article of the present invention further satisfies at least one of the following 1) to 5). 1) The standard deviation of the circularity distribution of the cells is between 0.05 and 0.15. 2) The cell contains hollow particles, and the hollow particles are particles having an outer shell containing a thermoplastic resin and a hollow part surrounded by the outer shell. 3) The average thickness of the outer shell of the hollow particle is 0.1 to 1.0 μm. 4) The thermoplastic resin contains a constituent unit having a carboxyl group. 5) The elastomer resin includes at least one selected from olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and polyester-based thermoplastic elastomers.

[0009] Preferably, the molded article of the present invention is produced by a production method comprising step 1 of extrusion-molding a foam-molding composition containing thermally expandable microspheres and a base resin including the elastomer resin, and step 2 of cooling the molded intermediate extruded in the step 1 through a cooling tank. The temperature of the cooling tank is preferably 50°C or lower. Effects of the Invention

[0010] The present invention provides a molded article having closed cells and excellent moldability. The molded article of the present invention is lightweight. The production method of the present invention can efficiently produce the above molded article. Brief Description of the Drawings

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of thermally expandable microspheres. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of hollow particles. Mode for Carrying Out the Invention

[0012] The present invention is a molded article in which cells are dispersed in a base resin containing an elastomer, wherein the average circularity of the cells is 0.5 to 0.9. The present invention is described in detail below.

[0013] Elastomer Resin The elastomer resin is an essential component contained in the base resin of the molded article of the present invention. The weight ratio of the elastomer resin in the base resin is not particularly limited, but is preferably 50 to 100% by weight from the viewpoint of production stability. The upper limit of the weight ratio is more preferably 99% by weight, still more preferably 97% by weight, and particularly preferably 95% by weight. On the other hand, the lower limit of the weight ratio is more preferably 60% by weight, still more preferably 80% by weight, and particularly preferably 90% by weight. The weight percentage of the base resin in the molded article of the present invention is not particularly limited, but is preferably 50 to 99% by weight in terms of improving cell dispersibility. The upper limit of this weight percentage is more preferably 98% by weight, even more preferably 97% by weight, and particularly preferably 95% by weight. On the other hand, the lower limit of this weight percentage is more preferably 60% by weight, even more preferably 80% by weight, and particularly preferably 90% by weight.

[0014] The elastomer resin is not particularly limited as long as it is an elastomer resin commonly used in foam molding, but it is preferable that it includes one selected from thermoplastic elastomers and rubber.

[0015] Thermoplastic elastomers are substances that soften upon heating, exhibit plasticity that allows them to be molded into desired shapes, and exhibit rubber elasticity at room temperature. Examples include mixtures of polymers consisting of hard segments and polymers consisting of soft segments, and copolymers of polymers consisting of hard segments and polymers consisting of soft segments. Examples of thermoplastic elastomers include olefin-based thermoplastic elastomers (TPO, TPV), styrene-based thermoplastic elastomers (TPS), polyurethane-based thermoplastic elastomers (TPU), polyester-based thermoplastic elastomers (TPC), polyamide-based thermoplastic elastomers (TPA), nitrile-based thermoplastic elastomers, and vinyl chloride-based thermoplastic elastomers.

[0016] Examples of olefin-based thermoplastic elastomers include hard segments made of polypropylene, propylene-ethylene copolymers, polyethylene, etc., and soft segments made of polyethylene or copolymers of ethylene with a small amount of diene component (e.g., ethylene-propylene copolymer (EPM), ethylene-propylene-diene copolymer (EPDM), EPDM partially crosslinked by adding organic peroxides). Furthermore, the polymer mixtures and copolymers as olefin-based thermoplastic elastomers may be graft-modified with unsaturated hydroxy monomers and their derivatives, unsaturated carboxylic acid monomers and their derivatives, etc.

[0017] Examples of commercially available olefin-based thermoplastic elastomers include "Santoprene" and "Vistamaxx" from ExxonMobil Corporation, "Excelink" from JSR Corporation, "Maxilon" from Showa Chemical Industries, Ltd., "Esporex TPE series" from Sumitomo Chemical Co., Ltd., "Engage" from Dow Chemical Japan Ltd., "Prime TPO" from Prime Polymer Co., Ltd., "Milastomer" from Mitsui Chemicals, Inc., "Zelus" and "Thermoran" from Mitsubishi Chemical Corporation, and "Multi-use Rheoestomer," "Actimer," and "Trinity" from Riken Technos Corporation.

[0018] Examples of styrene-based thermoplastic elastomers include hard segments made of polystyrene, for example, and soft segments made of polybutadiene, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene. Examples of such styrene-based thermoplastic elastomers include block copolymers such as styrene-butadiene-styrene (SBS) copolymer, styrene-isoprene-styrene (SIS) copolymer, styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, and styrene-butadiene-butylene-styrene (SBBS) copolymer.

[0019] Examples of commercially available styrene-based thermoplastic elastomers include "Toughbren," "Asablen," "Toughtech," and "SOE" from Asahi Kasei Corporation, "Elastomer AR" from Aron Kasei Co., Ltd., "Septon" and "Hybral" from Kuraray Co., Ltd., "JSR TR" and "JSR SIS" from JSR Corporation, "Maxilon" from Showa Kasei Kogyo Co., Ltd., "Triplen" and "Super Triplen" from Shinko Kasei Co., Ltd., "Esporex SB Series" from Sumitomo Chemical Co., Ltd., and "Rheostomer," "Actimer," "High-Performance Alloy Actimer," and "Actimer G" from Riken Technos Co., Ltd.

[0020] Polyurethane-based thermoplastic elastomers include polyurethanes produced by the reaction of diisocyanates with short-chain diols, which act as chain extenders, as hard segments, and polyurethanes produced by the reaction of polymer diols such as polyester diols, polyether diols, and polycarbonate diols with diisocyanates as soft segments. Polyurethane-based elastomers are block copolymers composed of alternating hard and soft segments.

[0021] Examples of polyurethane-based thermoplastic elastomers include "Rezamin" manufactured by Dainichi Seika Co., Ltd., "Miractran" manufactured by Tosoh Corporation, "Elastran" manufactured by BASF Japan Ltd., "Esten" manufactured by Nippon Looprisoll Co., Ltd., "Desmopan" and "Texin" manufactured by DIC Covestropolymer Co., Ltd., and "Maxilon" manufactured by Showa Kasei Kogyo Co., Ltd.

[0022] Polyester-based thermoplastic elastomers can include, for example, hard segments made of polybutylene terephthalate, and soft segments made of, for example, long-chain polyols or polyesters. Examples of polyester-based thermoplastic elastomers include "Tefablock" manufactured by Mitsubishi Chemical Corporation, "Hytrel" manufactured by Toray DuPont Ltd., "Perprene" manufactured by Toyobo Co., Ltd., and "Esteral" manufactured by Aron Kasei Co., Ltd.

[0023] Examples of rubbers include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, halogenated ethylene-α-olefin-non-conjugated diene copolymer rubber, sulfonated ethylene-α-olefin-non-conjugated diene copolymer rubber, maleated ethylene-α-olefin-non-conjugated diene copolymer rubber, butyl rubber, isobutylene isoprene rubber, and other diene rubbers; and non-diene rubbers such as hydrogenated nitrile rubber, urethane rubber, silicone rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylic rubber, epichlorohydrin rubber, fluororubber, polysulfurized rubber, and propylene oxide rubber.

[0024] Among thermoplastic elastomers, it is preferable to include at least one selected from olefin-based thermoplastic elastomers (TPO, TPV), styrene-based thermoplastic elastomers (TPS), polyurethane-based thermoplastic elastomers (TPU), and polyester-based thermoplastic elastomers (TPC), in order to stably produce molded articles, and it is particularly preferable to include olefin-based thermoplastic elastomers (TPO, TPV).

[0025] [Base resin] The base resin of the molded article of the present invention is not limited as long as it contains an elastomer resin, but in order to achieve the effects of the present invention, it is preferable to have a melting point or softening temperature below the expansion start temperature of the thermally expandable microspheres. The base resin may contain resins other than elastomer resins. Other resins include general thermoplastic resins such as polyethylene resins, polypropylene resins, polystyrene resins, polyvinyl chloride resins, polyester resins, polyamide resins, polycarbonate resins, polyvinyl chloride resins, acrylic resins, acrylonitrile-butadiene-styrene resins, and vinyl acetate resins. Among these, polyethylene-based resins and polypropylene-based resins are preferable in terms of stability and dispersibility.

[0026] When the base resin contains other resins, there are no particular limitations on the weight ratio of the other resins to the base resin, but 0.01% to 20% by weight is preferred in terms of improving cell dispersibility. The upper limit of this ratio is more preferably 15% by weight, even more preferably 10% by weight, and particularly preferably 5% by weight. On the other hand, the lower limit of this ratio is more preferably 0.1% by weight, even more preferably 0.5% by weight, and particularly preferably 1% by weight.

[0027] The MFR (melt flow rate) of the base resin is not particularly limited, but 0 to 200 g / 10 min is preferred due to its low fluidity and good handling properties. The upper limit of the MFR is more preferably 150 g / 10 min, even more preferably 130 g / 10 min, and particularly preferably 100 g / 10 min. On the other hand, the lower limit of the MFR is more preferably 0.01 g / 10 min, even more preferably 0.1 g / 10 min, and particularly preferably 1 g / 10 min. The MFR is measured using a capillary rheometer in accordance with JIS K7210, under conditions of a measurement temperature of 190°C and a load of 2.16 kg. The melting point of the base resin is not particularly limited, but is preferably between 100 and 300°C. If the temperature is 100°C or higher, fusion between resins is suppressed and workability is improved, and if the temperature is 300°C or lower, overheating of the thermally expandable microspheres during molding is suppressed and stable foaming properties can be achieved. The upper limit of the temperature is more preferably 280°C, even more preferably 260°C, and particularly preferably 250°C. On the other hand, the lower limit of the temperature is more preferably 120°C, even more preferably 130°C, and particularly preferably 150°C.

[0028] 〔cell〕 The cells dispersed in the molded article of this invention refer to void portions dispersed in the base resin. The cells have closed cells. The average circularity of the cells contained in the molded article of the present invention is 0.5 to 0.9. The reason why an average circularity of 0.5 to 0.9 results in a molded article with high moldability is not clear, but it is presumed that if the average circularity is less than 0.5, the durability of the base material is significantly reduced, and if it is greater than 0.9, the mechanical properties of the base material are improved. The lower limit of the average circularity is preferably 0.53, more preferably 0.55, particularly preferably 0.6, and most preferably 0.65. On the other hand, the upper limit of the average circularity is preferably 0.85, more preferably 0.83, particularly preferably 0.80, and most preferably 0.75. The method for measuring the average circularity of the cells described in the present invention is as described in the examples.

[0029] The standard deviation of the cell circularity distribution is not particularly limited, but 0.05 to 0.15 is preferred in terms of uniform dispersion. The upper limit of the standard deviation is more preferably 0.13, and even more preferably 0.1. The lower limit of the standard deviation is more preferably 0.06, and even more preferably 0.07. The method for measuring the standard deviation of the average circularity distribution of cells described in the present invention is as described in the examples.

[0030] There are no particular limitations on the number percentage of cells with a circularity of 0.9 or higher, but it is preferable that it be between 0 and 20% in order to ensure uniform dispersion in the base resin. The upper limit of this number percentage is more preferably 18%, and even more preferably 15%. The method for measuring the number percentage of cells with a circularity of 0.9 or higher described in this invention is as described in the examples.

[0031] The proportion of cells with a circularity of 0.4 or less is not particularly limited, but it is preferably 0 to 10% in order to maintain the durability of the molded article. The upper limit of this proportion is more preferably 8%, even more preferably 6%, and particularly preferably 5%. The method for measuring the proportion of cells with a circularity of 0.4 or less described in the present invention is as described in the examples.

[0032] The average diameter of the cells is not particularly limited, but it is preferably 1 to 200 μm in order to obtain a molded product with a good appearance. The upper limit of the diameter is more preferably 150 μm, and even more preferably 100 μm. On the other hand, the lower limit of the diameter is more preferably 10 μm, even more preferably 15 μm, and particularly preferably 20 μm. The method for measuring the average diameter of the cells described in the present invention is the method described in the examples.

[0033] The coefficient of variation CV of the cell diameter distribution is not particularly limited, but is preferably 1 to 50% in terms of the uniformity of the cell dispersion. The upper limit of the CV is more preferably 40%, and even more preferably 35%. On the other hand, the lower limit of the CV is more preferably 5%. The method for measuring the coefficient of variation CV of the cell diameter is as described in the examples.

[0034] [Hollow particles] The cells included in the molded article of the present invention are not particularly limited, but it is preferable that they include hollow particles. The hollow particles are preferably particles having an outer shell containing a thermoplastic resin and a hollow portion surrounded by the outer shell. Alternatively, the hollow particles may be expanded bodies of thermally expandable microspheres, as described later.

[0035] The thermoplastic resin contained in the outer shell of the hollow particles is not particularly limited, but it is preferably a polymer of polymerizable components. Furthermore, if the hollow particles are expanded bodies of thermally expandable microspheres, the thermoplastic resin forming the outer shell of the thermally expandable microspheres is also preferably a polymer of polymerizable components. Polymerizable components are components that essentially contain a monomer component having one radical-reactive carbon-carbon double bond (hereinafter sometimes simply referred to as a monomer), and may contain a crosslinking agent having two or more radical-reactive carbon-carbon double bonds (hereinafter sometimes simply referred to as a crosslinking agent). Both monomers and crosslinking agents are components that can undergo addition reactions, and the crosslinking agent is a component that can introduce a crosslinked structure into a thermoplastic resin.

[0036] Examples of monomers include nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; vinyl halogenated monomers such as vinyl chloride; vinylidene halogenated monomers such as vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid; and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, citraconic acid, and chloromaleic acid. Monomers containing carboxyl groups, such as anhydrides of unsaturated dicarboxylic acids and monoesters of unsaturated dicarboxylic acids, including monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate. (meth)acrylic acid ester monomers such as phenyl(meth)acrylate, isobornyl(meth)acrylate, cyclohexyl(meth)acrylate, benzyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate; (meth)acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, substituted methacrylamide; maleimide monomers such as N-phenylmaleimide, N-cyclohexylmaleimide; styrene monomers such as styrene, α-methylstyrene; Examples include ethylene unsaturated monoolefin monomers such as ethylene, propylene, and isobutylene; vinyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone; N-vinyl monomers such as N-vinylcarbazole and N-vinylpyrrolidone; vinyl naphthalene salts; and hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. In carboxyl group-containing monomers, some or all of the carboxyl groups may be neutralized during or after polymerization.In this invention, acrylic acid or methacrylic acid may be referred to as (meth)acrylic acid, and acrylate or methacrylate may be referred to as (meth)acrylate. Furthermore, (meth)acrylate means acrylate or methacrylate, and (meth)acrylic means acrylic or methacrylic. These other monomer components may be used individually or in combination of two or more.

[0037] It is preferable for the polymerizable component to contain a carboxyl group-containing monomer because it improves heat resistance. When the polymerizable component contains a carboxyl group-containing monomer, the weight percentage of the carboxyl group-containing monomer in the polymerizable component is not particularly limited, but is preferably 10 to 70% by weight. The upper limit of this weight percentage is more preferably 60% by weight, even more preferably 55% by weight, and particularly preferably 50% by weight. On the other hand, the lower limit of this weight percentage is more preferably 15% by weight, even more preferably 20% by weight, and particularly preferably 25% by weight.

[0038] It is preferable for the polymerizable component to contain a nitrile group-containing monomer because it improves the gas barrier properties. When the polymerizable component contains a nitrile group-containing monomer, the weight percentage of the nitrile group-containing monomer in the polymerizable component is not particularly limited, but is preferably 10 to 80% by weight. The upper limit of this weight percentage is more preferably 70% by weight, even more preferably 65% ​​by weight, and particularly preferably 60% by weight. On the other hand, the lower limit of this weight percentage is more preferably 15% by weight, even more preferably 20% by weight, and particularly preferably 25% by weight.

[0039] The polymerizable component is preferable because it improves heat resistance. When the polymerizable component contains a (meth)acrylamide monomer, the weight percentage of the (meth)acrylamide monomer in the polymerizable component is not particularly limited, but is preferably 0.1 to 50% by weight. The upper limit of this weight percentage is more preferably 40% by weight, even more preferably 30% by weight, and particularly preferably 20% by weight. On the other hand, the lower limit of this weight percentage is more preferably 1% by weight, even more preferably 3% by weight, and particularly preferably 5% by weight.

[0040] The polymerizable component is preferable because it improves foaming properties. When the polymerizable component contains a styrene monomer, the weight percentage of the styrene monomer in the polymerizable component is not particularly limited, but is preferably 0.1 to 50% by weight. The upper limit of this weight percentage is more preferably 40% by weight, even more preferably 30% by weight, and particularly preferably 20% by weight. On the other hand, the lower limit of this weight percentage is more preferably 2% by weight, even more preferably 3% by weight, and particularly preferably 5% by weight.

[0041] The polymerizable component is preferable because it improves foaming properties. When the polymerizable component contains a (meth)acrylic acid ester monomer, the weight percentage of the (meth)acrylic acid ester monomer in the polymerizable component is not particularly limited, but is preferably 0.1 to 50% by weight. The upper limit of this weight percentage is more preferably 40% by weight, even more preferably 30% by weight, and particularly preferably 20% by weight. On the other hand, the lower limit of this weight percentage is more preferably 1% by weight, even more preferably 3% by weight, and particularly preferably 5% by weight.

[0042] As described above, the polymerizable component may contain a crosslinking agent. By including a crosslinking agent, it is possible to suppress the decrease in the retention rate of hollow particles and the thermally expandable microspheres described later. Examples of crosslinking agents include alkanediolic di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, and 2-methyl-1,8-octanediolic di(meth)acrylate; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and PEG#200 di(meth)acrylate (the #200 in the compound name indicates that the weight-average molecular weight of the polyalkylene glycol chain portion within the molecule is 200, and the same applies to the # Arabic numerals listed below).Polyalkylene glycol di(meth)acrylates such as PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, PEG#1000 di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol #400 di(meth)acrylate, polypropylene glycol #700 di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polytetramethylene glycol #650 di(meth)acrylate, ethoxylated polypropylene glycol #700 di(meth)acrylate; ethoxylated bisphenol A di(meth)acrylate (EO addition 2-30), propoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A Examples include difunctional crosslinkable monomers such as sphenol A di(meth)acrylate, glycerin di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, dimethylol-tricyclodecane di(meth)acrylate, divinylbenzene, ethoxylated glycerin triacrylate, 1,3,5-tri(meth)acryloyl hexahydro-1,3,5-triazine, triallyl isocyanurate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-trivinylbenzene, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, as well as difunctional, trifunctional, and tetrafunctional or more crosslinkable monomers. The above crosslinking agents may be used individually or in combination of two or more.

[0043] There are no particular limitations on the amount of crosslinking agent, but it is preferably 0 to 5.0 parts by weight, more preferably 0.01 to 3.0 parts by weight, even more preferably 0.02 to 2.0 parts by weight, and most preferably 0.05 to 1.5 parts by weight per 100 parts by weight of polymerizable component. If the crosslinking agent content exceeds 5.0 parts by weight, the expansion performance of the thermally expandable microspheres may decrease.

[0044] The thermoplastic resin preferably contains structural units having carboxyl groups in terms of improving dispersibility, preferably contains structural units having nitrile groups in terms of improving heat resistance, and preferably contains structural units having phenyl groups in terms of increasing the strength of the molded article. Among these, it is more preferable to include structural units having carboxyl groups and / or structural units having nitrile groups, even more preferable to include structural units having carboxyl groups, and particularly preferable to include structural units having carboxyl groups and structural units having nitrile groups.

[0045] When the thermoplastic resin has a constituent unit having a nitrile group and a constituent unit having a carboxyl group, the constituent unit having a nitrile group (U N ) and a constituent unit having a carboxyl group (U c ) ratio (U N / U C The ratio of nitrile groups to carboxyl groups is preferably 1 / 2 to 10 / 1 in terms of heat resistance and solvent resistance. The upper limit of this ratio is more preferably 8 / 1, even more preferably 6 / 1, and particularly preferably 4 / 1. The ratio of these constituent units corresponds to the weight ratio of monomers having nitrile groups to monomers having carboxyl groups in the polymerizable component. Furthermore, the ratio of these constituent units can be measured by the ratio of the absorption peaks of each functional group in infrared spectroscopy (IR).

[0046] The hollow particles may contain components that vaporize upon heating. Furthermore, if the hollow particles are the expanded portion of the thermally expandable microspheres described later, the components that vaporize upon heating may be the foaming agents contained in the thermally expandable microspheres. Examples of components that vaporize upon heating include hydrocarbons with 3 to 13 carbon atoms such as propane, (iso)butane, (iso)pentane, (iso)hexane, (iso)heptane, (iso)octane, (iso)nonane, (iso)decane, (iso)undecane, (iso)dodecane, and (iso)tridecane; hydrocarbons with more than 13 carbon atoms but 20 or less, such as (iso)hexadecane and (iso)eicosane; hydrocarbons such as pseudocumene, petroleum ether, and petroleum fractions such as normal paraffins and isoparaffins with an initial boiling point of 150 to 260°C and / or a distillation range of 70 to 360°C; halides thereof; fluorine-containing compounds such as hydrofluoroethers; tetraalkylsilanes; and compounds that produce gas through thermal decomposition upon heating. One or more components may be used in combination to vaporize upon heating. The components that vaporize upon heating may be linear, branched, or alicyclic, and aliphatic components are preferred.

[0047] The encapsulation rate of components that vaporize upon heating contained in hollow particles is defined as the percentage of the weight of the components that vaporize upon heating contained within the hollow particles relative to the weight of the hollow particles. The encapsulation rate of the components is not particularly limited, but is preferably 1 to 50% by weight, more preferably 2 to 45% by weight, even more preferably 5 to 40% by weight, and most preferably 10 to 30% by weight relative to the weight of the hollow particles.

[0048] The average particle size of the hollow particles is preferably 0.5 to 100 μm, which results in a good appearance for the molded article. The upper limit of the average particle size is more preferably 80 μm, even more preferably 70 μm, and particularly preferably 50 μm. On the other hand, the lower limit of the average particle size is more preferably 1 μm, even more preferably 5 μm, and particularly preferably 10 μm.

[0049] The average thickness of the outer shell of the hollow particles is preferably 0.1 to 1.0 μm in order to obtain a sufficient lightweight effect. The upper limit of the average thickness is more preferably 0.9 μm, even more preferably 0.7 μm, and particularly preferably 0.5 μm. On the other hand, the lower limit of the average thickness is more preferably 0.2 μm, and even more preferably 0.3 μm. The method for measuring the average thickness of the outer shell of the hollow particles contained in the cell described in the present invention is as described in the examples.

[0050] When the molded article of the present invention contains hollow particles, the weight percentage of the hollow particles in the molded article is preferably 0.1 to 30% by weight. When the weight percentage of the hollow particles is 30% by weight or less, the strength of the molded article tends to improve, and when the weight percentage of the hollow particles is 0.1% by weight or more, a sufficient weight reduction effect can be obtained. The upper limit of the weight is more preferably 25% by weight, even more preferably 20% by weight, and particularly preferably 15% by weight. On the other hand, the lower limit of the weight is more preferably 0.5% by weight, even more preferably 0.8% by weight, and particularly preferably 1% by weight.

[0051] [Molded body] The specific gravity of the molded article of the present invention is preferably 0.2 to 0.8 in terms of good surface quality. The upper limit of the specific gravity is more preferably 0.75, even more preferably 0.7, and particularly preferably 0.65. On the other hand, the lower limit of the specific gravity is more preferably 0.3, particularly preferably 0.35, and most preferably 0.4. The method for evaluating the specific gravity of the molded article will be explained in the examples.

[0052] The foaming ratio of the molded article of the present invention is preferably 1.2 to 5 times, more preferably 1.3 to 3 times. When the foaming ratio is 5 times or less, the strength of the resulting molded article is increased and splintering of the surface of the molded article can be suppressed. The method for evaluating the foaming ratio of the molded article is as described in the examples.

[0053] The molded articles of the present invention are lightweight, have excellent heat insulation and sound insulation properties, and have a good appearance, making them suitable for applications such as sealing materials for building materials like window frame seals and door gaskets, sealing materials for automobiles like glass runs and body seals, interior materials for automobiles like instrument panels and door trims, exterior materials for automobiles like bumpers, wallpaper for buildings, flooring materials for buildings, soles of shoes, rolls for office automation equipment like transfer rolls and paper feed rolls, rolls for steelmaking, rolls for papermaking, wire rolls for printing, or industrial rolls. They are particularly suitable for sealing materials for building materials, sealing materials for automobiles, wallpaper, soles of shoes, artificial cork, or flooring materials.

[0054] [Method for manufacturing molded products] The molded article of the present invention can be manufactured by molding a foam molding composition containing thermally expandable microspheres and a base resin containing an elastomer resin. In this case, a masterbatch of thermally expandable microspheres may be used.

[0055] The weight percentage of thermally expandable microspheres in the foam molding composition is preferably 0.1 to 30% by weight. When the weight percentage of thermally expandable microspheres is 30% by weight or less, dispersibility tends to improve, and when the weight percentage of thermally expandable microspheres is 0.1% by weight or more, a sufficient lightweight effect can be obtained. The upper limit of this weight percentage is more preferably 25% by weight, even more preferably 20% by weight, and particularly preferably 15% by weight. On the other hand, the lower limit of this weight percentage is more preferably 0.5% by weight, even more preferably 0.8% by weight, and particularly preferably 1% by weight.

[0056] [Thermally expandable microspheres and methods for producing the same] The thermally expandable microspheres used in manufacturing the molded articles of the present invention have a core-shell structure consisting of an outer shell containing a thermoplastic resin and a foaming agent enclosed within it that vaporizes when heated, and exhibit thermal expandability (the property of the entire microsphere expanding when heated). The thermoplastic resin forming the outer shell of the thermally expandable microspheres is preferably a polymer of the polymerizable component described above. Furthermore, the foaming agent encapsulated within the thermally expandable microspheres is preferably a component that vaporizes upon heating.

[0057] The average particle size of the thermally expandable microspheres is not particularly limited, but is preferably 0.5 to 100 μm. When the particle size is within this range, the resulting bubble size is appropriate, and both sufficient lightweight effect and strength of the molded article can be achieved. The upper limit of the average particle size is more preferably 80 μm, even more preferably 65 μm, and particularly preferably 50 μm. On the other hand, the lower limit of the average particle size is more preferably 1 μm, even more preferably 5 μm, and particularly preferably 10 μm.

[0058] The coefficient of variation CV of the particle size distribution of thermally expandable microspheres is not particularly limited, but is preferably 50% or less, more preferably 45% or less, and especially preferably 40% or less. The coefficient of variation CV is calculated using the following formulas (1) and (2).

[0059]

number

[0060] The expansion start temperature of thermally expandable microspheres (T s The temperature is not particularly limited, but is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, particularly preferably 130°C or higher, and most preferably 150°C or higher, in terms of excellent heat resistance. The upper limit of the expansion start temperature of the thermally expandable microspheres is preferably 300°C. Maximum expansion temperature of thermally expandable microspheres (T max The temperature (T) is not particularly limited, but is preferably 150°C or higher, more preferably 170°C or higher, even more preferably 180°C or higher, particularly preferably 190°C or higher, and most preferably 200°C or higher, in terms of excellent heat resistance and expansion ratio. The upper limit of the maximum expansion temperature is preferably 350°C. Note that the expansion start temperature (T) of the thermally expandable microsphere s ) and maximum expansion temperature (T max The measurement method is as described in the examples.

[0061] The maximum volume expansion ratio of the thermally expandable microspheres is not particularly limited, but is preferably 3 times or more, more preferably 10 times or more, even more preferably 20 times or more, particularly preferably 30 times or more, even more preferably 50 times or more, and most preferably 70 times or more. On the other hand, the upper limit of the maximum expansion ratio is preferably 200 times.

[0062] A method for producing thermally expandable microspheres includes a step of dispersing an oily mixture containing a polymerizable component and a foaming agent in an aqueous dispersion medium and polymerizing the polymerizable component (hereinafter sometimes simply referred to as the polymerization step). The polymerizable component and foaming agent used in the method for producing thermally expandable microspheres are those described above.

[0063] In the method for producing thermally expandable microspheres, the polymerizable component may be polymerized in the presence of a polymerization initiator. Using a polymerization initiator is preferable because it allows for the efficient production of thermally expandable microspheres. The polymerization initiator is preferably included in the oily mixture together with the polymerizable component and the foaming agent.

[0064] Examples of polymerization initiators include peroxides and azo compounds. Examples of peroxides include peroxydicarbonates such as diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and dibenzyl peroxydicarbonate; diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; peroxyketals such as 2,2-bis(t-butylperoxy)butane; hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide; dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; and peroxyesters such as t-hexyl peroxypivalate and t-butyl peroxyisobutyrate.

[0065] Examples of azo compounds include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis(cyclohexane-1-carbonitride). The amount of polymerization initiator is not particularly limited, but is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and most preferably 0.2 to 5 parts by weight, per 100 parts by weight of polymerizable component. When the amount of polymerization initiator is within the above range, the heat resistance and expansion performance of the resulting thermally expandable microspheres tend to be high.

[0066] In the polymerization process, the aqueous dispersion medium is a medium for dispersing an oily mixture that includes polymerizable components and a foaming agent, and is mainly composed of water such as deionized water. The aqueous dispersion medium may further contain alcohols such as methanol, ethanol, or propanol, or hydrophilic organic solvents such as acetone. In this invention, hydrophilicity means being miscible with water. There are no particular limitations on the amount of aqueous dispersion medium used, but it is preferable to use 100 to 1000 parts by weight of aqueous dispersion medium per 100 parts by weight of polymerizable components.

[0067] The aqueous dispersion medium may further contain an electrolyte. Examples of electrolytes include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium carbonate. These electrolytes may be used individually or in combination of two or more. There are no particular limitations on the electrolyte content, but it is preferable to contain 0.1 to 50 parts by weight per 100 parts by weight of aqueous dispersion medium.

[0068] The aqueous dispersion medium may contain at least one water-soluble compound selected from water-soluble 1,1-substituted compounds having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group, and a phosphonic acid (salt) group and a heteroatom are bonded to the same carbon atom, potassium dichromate, alkali metal nitrite salts, metal (III) halides, boric acid, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble vitamin B compounds, and water-soluble phosphonic acid (salts). In this invention, "water-soluble" means a state in which 1 g or more dissolves per 100 g of water.

[0069] There are no particular limitations on the amount of water-soluble compound contained in the aqueous dispersion medium, but it is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 0.1 parts by weight, and especially preferably 0.001 to 0.05 parts by weight, per 100 parts by weight of polymerizable component. If the amount of water-soluble compound is too small, the effect of the water-soluble compound may not be sufficiently obtained. On the other hand, if the amount of water-soluble compound is too large, the polymerization rate may decrease or the amount of residual polymerizable component, which is the raw material, may increase.

[0070] In addition to electrolytes and water-soluble compounds, aqueous dispersion media may also contain dispersion stabilizers and dispersion stabilization aids. Examples of dispersion stabilizers include tricalcium phosphate, magnesium pyrophosphate obtained by a double decomposition method, calcium pyrophosphate, colloidal silica, alumina sol, and magnesium hydroxide. These dispersion stabilizers may be used individually or in combination of two or more. The amount of dispersion stabilizer is preferably 0.05 to 30 parts by weight, and more preferably 0.2 to 20 parts by weight, per 100 parts by weight of polymerizable component.

[0071] There are no particular limitations on the dispersion stabilization aids, but examples include polymer-type dispersion stabilization aids, cationic surfactants, anionic surfactants, amphoteric surfactants, nonionic surfactants, and other surfactants. These dispersion stabilization aids may be used individually or in combination of two or more types.

[0072] The aqueous dispersion medium is prepared, for example, by mixing water (ion-exchanged water) with a water-soluble compound and, if necessary, a dispersion stabilizer and / or dispersion stabilization aid. The pH of the aqueous dispersion medium during polymerization is appropriately determined depending on the type of water-soluble compound, dispersion stabilizer, and dispersion stabilization aid. Specifically, when colloidal silica is used as the dispersion stabilizer, it is preferably adjusted to an acidic range, and when magnesium hydroxide is used as the dispersion stabilizer, it is preferably adjusted to an alkaline range.

[0073] In the polymerization process, chain transfer agents, organic pigments, inorganic pigments or inorganic particles with hydrophobic surfaces may be used, and polymerization may be carried out in the presence of sodium hydroxide, or sodium hydroxide and zinc chloride.

[0074] In the polymerization process, an oily mixture is suspended and dispersed in an aqueous dispersion medium so that spherical oil droplets of a predetermined particle size are prepared. Methods for suspending and dispersing oily mixtures include, for example, stirring with a homomixer (e.g., manufactured by Primix Co., Ltd.), using a static dispersion device such as a static mixer (e.g., manufactured by Noritake Co., Ltd.), and general dispersion methods such as membrane emulsification and ultrasonic dispersion. Next, suspension polymerization is initiated by heating the aqueous suspension in which the oily mixture is dispersed as spherical oil droplets in an aqueous dispersion medium. During the polymerization reaction, it is preferable to stir the aqueous suspension, and the stirring should be done gently enough to prevent, for example, the floating of monomer components and the settling of thermally expandable microspheres after polymerization.

[0075] The polymerization temperature can be freely set depending on the type of polymerization initiator, but is preferably controlled within the range of 30 to 100°C, and more preferably within the range of 40 to 90°C. The time for maintaining the reaction temperature is preferably about 0.1 to 20 hours. There are no particular limitations on the initial polymerization pressure, but it is preferably 0 to 5.0 MPa, and more preferably 0.1 to 3.0 MPa in gauge pressure.

[0076] The method for manufacturing a molded article of the present invention preferably includes a step of molding a foam molding composition at a temperature close to the maximum expansion temperature of the thermally expandable microspheres contained in the foam molding composition. There are no particular limitations on the molding method, but extrusion molding is preferred in that it achieves the effects of the present invention. Other methods include injection molding, calendering, inflation molding, hollow molding, kneading molding, compression molding, vacuum molding, and thermoforming.

[0077] A method for producing a molded article of the present invention is preferable in that it includes a step 1 of extruding a foam molding composition containing thermally expandable microspheres and a base resin containing an elastomer resin, and a step 2 of cooling the molded intermediate extruded in step 1 through a cooling tank, in order to stably produce the molded article of the present invention. The extrusion molding machine used preferably has a heater and thermocouple in the cylinder section and is equipped with a raw material supply port for supplying the intermediate. Preferably, a screw is installed inside the cylinder to further melt and / or soften the intermediate and move it in the extrusion direction from the raw material supply port while kneading it.

[0078] In step 1, the foam molding composition supplied into the cylinder is heated within the cylinder to a temperature above the melting or softening point of the base resin and close to the maximum expansion temperature of the contained thermally expanded microspheres (molding temperature of the molded body), thereby becoming a melted and / or softened kneaded material that can be molded into the desired shape. The material is then extruded through a die equipped with a heater and a thermocouple to obtain a molded body. Here, the molding temperature of the molded body refers to the temperature of the molten and / or softened mixture as it moves through the cylinder of the molding machine.

[0079] The molding temperature of the molded article is preferably 160 to 250°C, from the viewpoint of the foaming ratio of the molded article. The upper limit of this temperature is more preferably 230°C, even more preferably 220°C, and particularly preferably 210°C. On the other hand, the lower limit of this temperature is more preferably 170°C, even more preferably 175°C, and particularly preferably 180°C.

[0080] When an extrusion molding machine is equipped with a vent during the manufacturing process of a molded product, it is desirable to perform the molding with the vent closed. If the vent is open, the molten mixture may be extruded through the vent, making it difficult to obtain a lightweight molded product. Furthermore, in extrusion molding, it is possible to connect a vacuum pump or the like to a vent located directly in front of the die and exhaust the mixture to remove voids generated during mixing.

[0081] In the manufacturing process of a molded product, the time from when the foam molding composition is introduced into the raw material supply port until it is extruded from the die can be adjusted by the rotation speed of the screw. The rotation speed of the screw can be set appropriately depending on the equipment and the type of base resin, but the time from when the molding composition is introduced into the raw material supply port until it is extruded from the die (residence time) is preferably 0.5 to 20 minutes, more preferably 0.7 to 15 minutes, even more preferably 0.7 to 10 minutes, and particularly preferably 1 to 7 minutes. If the residence time is 0.5 minutes or more, heating is sufficient and the expandable microspheres expand sufficiently, and the molded product tends to have the desired foaming ratio. On the other hand, if the residence time is 20 minutes or less, work efficiency tends to improve and productivity tends to increase.

[0082] In step 2, it is preferable, in terms of achieving the effects of the present invention, that after the softened foam molding composition passes through the die, the molded intermediate extruded from the die is cooled in a cooling tank such as a water cooler or roller cooler. The molded intermediate that has passed through the cooling tank is then molded to the desired length and shape, resulting in a lightweight molded body.

[0083] In step 2, it is preferable that the temperature of the cooling tank be 50°C or lower in order to improve moldability through rapid cooling. The lower limit of this temperature is preferably 0°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher. On the other hand, the upper limit of this temperature is more preferably 45°C or lower, even more preferably 40°C or lower, and particularly preferably 30°C or lower. Furthermore, it is preferable that the temperature of the cooling tank be maintained at 50°C or lower. Water is preferred as the refrigerant for the cooling tank in terms of cooling efficiency.

[0084] The foam molding composition may further contain other components as needed, such as chemical blowing agents, stabilizers, fillers, plasticizers, lubricants, softeners, humidifiers, colorants, antistatic agents, rubber vulcanization / crosslinking agents, and vulcanization accelerators.

[0085] Examples of chemical blowing agents include inorganic chemical blowing agents such as ammonium carbonate, sodium bicarbonate, and anhydrous sodium nitrate; and organic chemical blowing agents such as dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'-dinitrosotelephthalamide, benzenesulfonyl hydrazide, p,p'-oxybis(benzenesulfonyl hydrazide), and azodicarbamide. In addition, blowing aids such as urea-based, organic acid-based, and metal salt-based blowing agents may be used in combination with these chemical blowing agents. One or more of these chemical blowing agents and blowing aids may be used in combination.

[0086] Examples of stabilizers include antioxidants such as phenolic stabilizers, sulfur-based stabilizers, phosphorus-based stabilizers, organotin-based stabilizers, lead-based stabilizers, calcium-zinc-based stabilizers, and other calcium-zinc-based stabilizers, as well as light stabilizers such as UV absorbers and hindered amine-based stabilizers, and hydrotalcite. These stabilizers may be used individually or in combination of two or more types.

[0087] The filler may be either an inorganic or organic filler. Examples of inorganic fillers include glass fibers (including those coated with metal), carbon fibers (including those coated with metal), potassium titanate, silicon carbide, silicon nitride, ceramic fibers, metal fibers, aramid fibers, barium sulfate, calcium sulfate, calcium silicate, calcium carbonate, magnesium carbonate, antimony trioxide, zinc oxide, titanium oxide, magnesium oxide, iron oxide, molybdenum disulfide, magnesium hydroxide, aluminum hydroxide, mica, talc, kaolin, pyrophyllite, bentonite, sericite, zeolite, wollastonite, alumina, clay, ferrite, graphite, gypsum, glass beads, glass balloons, quartz, and the like. Examples of organic fillers include plant fibers such as cellulose, kenaf, and wheat bran; animal fibers such as wool and silk; synthetic fibers such as aramid fibers, phenolic fibers, polyester fibers, acrylic fibers, polyolefin fibers such as polyethylene and polypropylene, polyvinyl alcohol fibers, polyvinyl chloride fibers, and fluororesin fibers; regenerated fibers such as rayon; semi-synthetic fibers such as cellulose acetate; and polysaccharides such as wood flour, bamboo flour, okara (soy pulp), rice husks, fruit husk powder, monosaccharides, and starch. These fillers may be used individually or in combination of two or more types.

[0088] Examples of plasticizers include diisononyl phthalate (DINP), dioctyl phthalate (DOP), dibutyl phthalate (DBP), butyl octyl phthalate (BOP), diisononyl adipate (DINA), trioctyl trimetate (TOTM), tricresyl phosphate (TCP), tributyl acetyl citrate (ATBC), epoxidized soybean oil, and epoxidized linseed oil. These plasticizers may be used individually or in combination of two or more.

[0089] Examples of lubricants include metal soaps such as calcium stearate, magnesium stearate, barium stearate, lead stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, and calcium ricinoleate; hydrocarbons such as paraffin wax and liquid paraffin; amide waxes such as stearamide, oleamide, erucamide, methylenebisstearateamide, and ethylenebisstearateamide; fatty acid esters such as monoglyceride stearate, stearyl stearate, and butyl stearate; fatty acids such as stearic acid; higher alcohols such as stearyl alcohol; and modified polytetrafluoroethylenes. These lubricants may be used individually or in combination of two or more.

[0090] The softening agent or humidifying agent is not particularly limited as long as it is a liquid compound that can be mixed with the base resin to soften the base resin, or that can be mixed with the aforementioned heat-expandable microspheres to create wet powdery heat-expandable microspheres (hereinafter sometimes referred to as wet powdery microspheres) that can suppress the powdering of the heat-expandable microspheres. Examples include organic liquid compounds such as alkylene glycol, polyalkylene glycol, glycerin, process oil, liquid paraffin, naphthenic oil, aromatic oil, and fats and oils; and inorganic liquid compounds such as silicone oil. Organic liquid compounds are preferred in terms of achieving the effects of the present invention, and process oil, silicone oil, and liquid paraffin are more preferred. These softening agents may be used individually or in combination of two or more. Examples of colorants include carbon black, titanium dioxide, kaolin, chromium yellow, phthalocyanine blue, and red lead. There are no particular limitations on the antistatic agent, but examples include anionic antistatic agents and nonionic antistatic agents.

[0091] Examples of rubber vulcanizing and crosslinking agents include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur; inorganic vulcanizing agents such as sulfur chloride, selenium, and tellurium; sulfur-containing organic compounds such as morpholine disulfide, alkylphenol disulfides, thiuram disulfides, and dithiocarbamate; and organic peroxides such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, di-t-butylperoxide, dicumylperoxide, t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 1,3-bis-(t-butylperoxyisopropyl)benzene. These rubber vulcanizing and crosslinking agents may be used individually or in combination of two or more.

[0092] Examples of vulcanization accelerators include aldehyde ammonias such as hexamethylenetetramine; guanidines such as diphenylguanidine, di(o-tolyl)guanidine, and o-tolylupiguanide; thioureas such as thiocarbanilide, di(o-tolyl)thiourea, N,N'-diethylthiourea, and dilaurylthiourea; thiazoles such as mercaptobenzothiazole, dibenzothiazole disulfide, and N,N'-di(ethylthiocarbamoylthio)benzothiazole; and Nt- Examples include sulfenamides such as butyl-2-benzothiadylsulfenamide; thirams such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabutylthiuram disulfide; carbamates such as zinc dimethylthiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate, and iron dimethylthiocarbamate; and xanthogenic salts such as zinc butylthiooxantate. These vulcanization accelerators may be used individually or in combination of two or more.

[0093] Among the other components listed above, chemical blowing agents, stabilizers, fillers, plasticizers, lubricants, softeners, humectants, colorants, antistatic agents, rubber vulcanizing / crosslinking agents, vulcanization accelerators, and their decomposition products may be included in the molded article.

[0094] Hereinafter, examples of the molded article of the present invention will be specifically described. The present invention is not limited to these examples. In the following examples and comparative examples, "%" means "% by weight" and "part" means "part by weight" unless otherwise specified. Physical properties were measured and performance was further evaluated in accordance with the procedures described below for the thermally expandable microspheres listed in the following production examples and the molded articles listed in the examples and comparative examples. Hereinafter, thermally expandable microspheres may be simply referred to as "microspheres" for brevity.

[0095] (Evaluation of Thermally Expandable Microspheres) [Measurement of Average Particle Diameter (D50) of Thermally Expandable Microspheres] A Microtrac particle size distribution analyzer (model 9320-HRA) manufactured by Nikkiso Co., Ltd. was used as the measuring apparatus, and the D50 value obtained by volume-based measurement was taken as the average particle diameter.

[0096] [Expansion Initiation Temperature of Thermally Expandable Microspheres (T s ) and Maximum Expansion Temperature (T max ) Measurement] DMA (Model DMA Q800, manufactured by TA Instruments) was used as the measuring apparatus. 0.5 mg of microspheres was placed in an aluminum cup having a diameter of 5.6 mm and a depth of 4.8 mm, and an aluminum lid (5.6 mm in diameter, 0.1 mm in thickness) was placed on top of the microsphere layer to prepare a sample. The sample height was measured while a force of 0.01 N was applied from above to the sample by a pressurizer. The sample was heated from 20°C to 300°C at a heating rate of 10°C / min while a force of 0.01 N was applied by the pressurizer, and the displacement of the pressurizer in the vertical direction was measured. The temperature at which displacement starts in the positive direction is defined as the expansion initiation temperature (T s ) and the temperature at which the maximum displacement (H max ) is obtained is defined as the maximum expansion temperature (T max ). A higher T max indicates excellent heat resistance and high expansion properties.

[0097] [Moisture Content of Thermally Expandable Microspheres (C w1 ) Measurement] The moisture content (by weight) of the thermally expandable microspheres was measured using a Karl Fischer moisture meter (MKA-510N model, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). w1 That's what I decided.

[0098] [Measurement of the encapsulation rate (C1) of foaming agent in thermally expandable microspheres] 1.0 g of thermally expandable microspheres were placed in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, and their weight (W1 (g)) was measured. 30 ml of acetonitrile was added and the spheres were uniformly dispersed. After standing at room temperature for 24 hours, the weight (W2 (g)) was measured after drying under reduced pressure at 130°C for 2 hours. The encapsulation rate (C1) of the foaming agent in the thermally expandable microspheres was calculated using the following formula. C1(weight%)=100×{100×(W1-W2) / 1.0-C w1 } / (100-C w1 ) (In the formula, the water content of thermally expandable microspheres C w1 (This was measured using the method described above.)

[0099] (Evaluation of molded products) [Measurement of average cell diameter and CV] The molded body was cut, and the resulting cross-section was sputtered with platinum. Then, an electron microscope image was obtained using a scanning electron microscope (KEYENCE VE-8800) under conditions of an acceleration voltage of 20kV and a magnification of 30x. From these electron microscope images, 100 arbitrary cells (bubbles) were analyzed for their bubble diameter and CV value using the image analysis particle size distribution measurement software Mac-View (Mountec Co., Ltd.).

[0100] [Measurement of the mean circularity and standard deviation of cells] Similar to the average diameter of the cells mentioned above, the cells were observed using an electron microscope, and the projected area (A) (projected area) and perimeter (B) of 100 arbitrary cells (bubbles) were measured. The circularity of each cell was then calculated using the following formula. The average circularity and standard deviation were calculated from the circularity of the 100 cells obtained. Circularity = 4πA / B 2 Furthermore, regarding the circularity of the cells calculated above, the number of cells with a circularity of 0.9 or higher and the number of cells with a circularity of 0.4 or lower were counted, and the percentage of cells with a circularity of 0.9 or higher and the percentage of cells with a circularity of 0.4 or lower were calculated using the following formulas. Percentage of cells with a circularity of 0.9 or higher (%) = Number of cells with a circularity of 0.9 or higher / Number of cells measured × 100 Percentage of cells with a circularity of 0.4 or less (%) = Number of cells with a circularity of 0.4 or less / Number of cells measured × 100

[0101] [Measurement of the average thickness of the outer shell of hollow particles contained in a cell] The thickness of the shell of an arbitrary hollow particle was measured from SEM images of the cross-section of the obtained molded body taken at 100x magnification, and the result was calculated from the average value of the shell thicknesses of 20 hollow particles.

[0102] [Measurement of Young's modulus of molded articles] Based on JIS K7171, a test specimen measuring 80 mm in length, 25 mm in width, and 2 mm in thickness, cut from the obtained molded body, was evaluated for three-point bending flexibility using an Instron universal testing machine (Instron Corporation). The test specimen was set on a jig with a pair of support columns spaced 64 mm apart, and the bending modulus of elasticity (MPa) was measured while the test specimen was pressed from above at a speed of 1 mm / min at the center between the columns. The moldability was calculated from the measured bending modulus of elasticity and the modulus of elasticity of the base resin using the following formula, and the moldability of the molded body was determined based on the following evaluation criteria, with a score of ○ or higher being considered a pass. Degree of molding process = Elastic modulus of the molded body / Elastic modulus of the base resin ◎: The degree of molding is between 0.7 and 0.8, indicating excellent moldability. ○: The degree of molding is 0.6 or higher but less than 0.7 or greater than 0.8 and 0.9 or less, indicating excellent moldability. ×: The degree of molding is less than 0.6 or greater than 0.9, indicating poor moldability. [Measurement of specific gravity and foaming ratio of molded body] The specific gravity (D1) of the molded body was measured using the immersion method with a precision hydrometer AX200 (manufactured by Shimadzu Corporation). Next, the specific gravity (D2) of the base molded body formed from the base resin was measured. The foaming ratio of the molded body was calculated using the following formula. The foaming ratio of the molded body (times) = D2 / D1 [Evaluation of the appearance of the molded product] The obtained foam molded body was prepared to a width of 15 cm and a length of 50 cm. The prepared foam molded body was visually inspected and judged based on the following evaluation criteria, with a score of ○ or higher being considered a pass. ◎: Fewer than 5 indentations due to the fracture of thermally expandable microspheres, no surface roughness, and good condition. ○: There are 5 to 15 indentations caused by the fracture of thermally expandable microspheres, and the surface roughness is minimal, indicating good quality. ×: More than 15 indentations due to the destruction of thermally expandable microspheres, resulting in a rough surface and a defective product.

[0103] (Manufacturing of thermally expandable microspheres) <Manufacturing Example 1> To prepare an aqueous dispersion medium, 130 parts sodium chloride was dissolved in 500 parts deionized water, and 1.0 part polyvinylpyrrolidone, 0.05 parts carboxymethylated polyethyleneimine sodium salt, and 65 parts colloidal silica (effective concentration 20%) were added. The pH was then adjusted to 3.0. Separately, 40 parts acrylonitrile, 25 parts methacrylic acid, 25 parts methacrylonitrile, 5 parts methacrylamide, 5 parts styrene, 0.8 parts 1,9-nonanediol diacrylate, 0.8 parts perloyl OPP (di-2-ethylhexyl peroxydicarbonate (70% purity)), and 36 parts isopentane were mixed and dissolved to form an oily mixture. An aqueous dispersion medium and an oily mixture were mixed, and the resulting mixture was dispersed for 1 minute at a rotation speed of 10,000 rpm using a homomixer (TK Homomixer, manufactured by Primix Corporation) to prepare an aqueous suspension. The obtained aqueous suspension was transferred to a 1.5-liter pressurized reactor, purged with nitrogen, and the initial reaction pressure was set to 0.35 MPa. Polymerization was carried out at a polymerization temperature of 60°C for 20 hours while stirring at 80 rpm. After polymerization, the product was filtered and dried to obtain thermally expandable microspheres A1. The physical properties of the obtained thermally expandable microspheres were evaluated. The results are shown in Table 1. <Manufacturing Examples 2-5> Manufacturing Examples 2-5 were conducted in the same manner as Manufacturing Example 1, except for the modifications shown in Table 1, to obtain the thermally expandable microspheres A2-A5. The results are shown in Table 1.

[0104] (Examples 1-9 and Comparative Examples 1-5) (Example 1) 950 parts by weight of olefin-based elastomer (Milastomer 8032BS, manufactured by Mitsui Chemicals, Inc., flexural modulus 60 MPa, A hardness 79, specific gravity 0.89) and 50 parts by weight of microspheres A1 obtained in Production Example 1 were combined to form a 1000 parts by weight mixture. This mixture was supplied from the raw material supply port of a Laboplast Mill extrusion molding machine (manufactured by Toyo Seiki Co., Ltd.). The temperature of the mixture in the cylinder was set to 200°C, the temperature of the T-die (width 150 mm, lip thickness 2.1 mm) was set to 200°C, and the molding intermediate was extruded at a screw rotation speed of 40 rpm. The extruded molding intermediate was cooled by passing it through a cooling tank (cooling medium: water) adjusted to a temperature of 20°C to obtain a sheet-like foamed molded body (width 148 mm, thickness 2.0 mm) having closed cells. Table 2 shows the results of the evaluation of the physical properties of the obtained molded body.

[0105] (Examples 2-9 and Comparative Examples 1-5) Examples 2-7 and Comparative Examples 1-5 used the same base resin as in Example 1, and molded articles with closed cells were produced in the same manner, except that other conditions were changed as shown in Tables 2-4. The results are shown in Tables 2-4. Example 8 was prepared in the same manner as in Example 1, except that the base resin was a styrene-based elastomer (flexural modulus 10.4 MPa, A hardness 75, specific gravity 0.93), and the other conditions were changed as shown in Table 3. The results are shown in Table 3. Example 9 was prepared in the same manner as in Example 1, except that the base resin was a polyester elastomer (Toray DuPont Co., Ltd., Hytrel 4777, flexural modulus 94.1 MPa, D hardness 47, specific gravity 1.15), and the other conditions were changed as shown in Table 3. The results are shown in Table 3.

[0106] [Table 1]

[0107] [Table 2]

[0108] [Table 3]

[0109] [Table 4]

[0110] As can be seen from Tables 2-4, a molded article in which cells are dispersed in a base resin containing an elastomer resin, and in which the average circularity of the cells is 0.5-0.9, exhibits high moldability (Examples 1-9). On the other hand, if the circularity of the molded body is not between 0.5 and 0.9 (comparisons 1 to 5), the moldability is poor. [Industrial applicability]

[0111] According to the present invention, it is possible to provide a lightweight molded article that has closed cells, excellent moldability, and good formability. Furthermore, it is possible to provide a manufacturing method that can efficiently produce the said molded article. [Explanation of Symbols]

[0112] 1. Outer shell containing thermoplastic resin 2. Foaming agent (core) 3. Outer shell containing thermoplastic resin 4 hollow part< / x>

Claims

1. A foamed molded article in which cells are dispersed in a base resin containing an elastomer resin, The cell contains hollow particles, The hollow particle is a particle having an outer shell containing a thermoplastic resin and a hollow portion surrounded by the outer shell. The average circularity of the aforementioned cells is 0.5 to 0.

9. A foamed molded body in which the proportion of cells with a circularity of 0.9 or higher among the aforementioned cells is 0 to 20%.

2. The foamed molded article according to claim 1, wherein the standard deviation of the circularity distribution of the cells is 0.05 to 0.

15.

3. The foamed molded article according to claim 1 or 2, wherein the average thickness of the outer shell portion of the hollow particles is 0.1 to 1.0 μm.

4. The foamed molded article according to any one of claims 1 to 3, wherein the thermoplastic resin contains a constituent unit having a carboxyl group.

5. The foamed molded article according to any one of claims 1 to 4, wherein the elastomer resin comprises at least one selected from olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and polyester-based thermoplastic elastomers.

6. A method for manufacturing a molded article in which cells are dispersed in a base resin containing an elastomer resin, and the average circularity of the cells is 0.5 to 0.9, The process comprises: step 1 of extruding a foam molding composition containing thermally expandable microspheres and a base resin containing the elastomer resin; and step 2 of cooling the molded intermediate extruded in step 1 via a cooling tank. The expansion start temperature of the aforementioned thermally expandable microspheres is 100 to 176°C. A method for manufacturing a molded article, wherein the molding temperature of the molded article in step 1 is 180 to 250°C.

7. The method for manufacturing a molded article according to claim 6, wherein the temperature of the cooling tank is 50°C or lower.

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