Polymer, additive for resin, resin composition and molding of the same

Abstract

To provide a polymer which enables provision of a resin composition that can cope with various molding methods, and can yield high surface smoothness and a high expansion ratio, especially when being applied to foam molding.SOLUTION: A polymer contains a constitutional unit derived from alkyl methacrylate having an alkyl group having less than 6 carbon atoms, and a constitutional unit derived from alkyl acrylate having a (meth)alkyl group having 6 or more carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer, a resin additive, a resin composition, and a molded article thereof. More specifically, the present invention relates to a polymer that can provide a resin composition that has high melt tension during melt kneading and exhibits excellent appearance when foam-molded, a resin additive containing the polymer, and a resin composition using the polymer. [Background technology]

[0002] Polyester resins are used in automobile components, home appliance and office equipment components, and building materials due to their excellent mechanical properties, heat resistance, chemical resistance, and electrical properties. Furthermore, in recent years, environmental issues caused by waste plastics have come to the forefront, spurring a global demand for a recycling-oriented society. In this context, various studies have been conducted to expand the application of plant-derived polyester resins to components. In particular, there is a growing demand for foam-molded products using polyester resins, due to their ability to reduce the amount of resin used, lighten components, and provide functionality. Examples of such polyester resins include polylactic acid, polybutylene succinate, 3-hydroxybutyrate / 3-hydroxyhexanoate copolymer, polycaprolactone, and partially biomass-based plastics. Examples of partially biomass-based plastics include polyethylene terephthalate, obtained by polymerizing biomass-derived ethylene glycol and petroleum-derived terephthalic acid, and polybutylene terephthalate, obtained by polymerizing biomass-derived butylene glycol and the aforementioned terephthalic acid.

[0003] However, polyester resins have a problem in that their low melt strength limits the molding methods they can be used in. For example, their application to foam molding, blow molding, vacuum molding, and other processes that require melt strength is limited. To address these problems with polyester resins, a method has been proposed in which a high-molecular-weight acrylic resin is added to the polyester resin, primarily for the purpose of imparting melt strength (Patent Documents 1 and 2). Another method has been proposed in which a modifier reactive with the polyester resin is added (Patent Documents 2 and 3). Furthermore, methods reported for foaming applications include a method using a resin composition in which a predetermined amount of deodorant is added to polylactic acid (Patent Document 5), and a method using a polyester resin composition containing an aliphatic polyester with a predetermined structure and a predetermined azo-based blowing agent (Patent Document 6). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-45487 [Patent Document 2] Japanese Patent Application Publication No. 8-59949 [Patent Document 3] Japanese Patent Application Publication No. 6-41376 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-254541 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-239738 [Patent Document 6] Japanese Patent Application Laid-Open No. 2015-52045 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the addition of conventional high-molecular-weight acrylic resins is insufficient in improving melt strength, and the addition of reactive modifiers significantly impairs the fluidity of the resin composition. Therefore, it is difficult to achieve both moldability and melt tension with the techniques disclosed in Patent Documents 1 to 3. Furthermore, even when the resin compositions described in Patent Documents 5 and 6 are applied to foam molding, the effects of improving foam cell uniformity, surface smoothness of the molded product, and expansion ratio are insufficient.

[0006] In view of the above circumstances, there is a strong demand for a method for providing a resin composition that has excellent melt tension and that can achieve high surface smoothness and a high expansion ratio when applied to foam molding.

[0007] Therefore, one aspect of the present invention has as its main object the provision of a polymer that can be used in a wide range of molding methods, and that can provide a resin composition that can achieve high surface smoothness and a high expansion ratio when applied to foam molding in particular. Another aspect of the present invention has as its main object the provision of a resin additive containing the polymer, a resin composition containing the polymer and a polyester resin, and a molded article made of the resin composition. [Means for solving the problem]

[0008] A first aspect of the present invention is a polymer containing a structural unit derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms and a structural unit derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms.

[0009] A second aspect of the present invention is the polymer according to the first aspect, wherein the alkyl group of the (meth)acrylic acid alkyl ester having an alkyl group having 6 or more carbon atoms has 8 or more carbon atoms.

[0010] A third aspect of the present invention is the polymer according to the first or second aspect, wherein the content of the structural units derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms is 30 to 99 mass % and the content of the structural units derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms is 1 to 70 mass % relative to 100 mass % of the polymer.

[0011] A fourth aspect of the present invention is a resin additive comprising the polymer according to any one of the first to third aspects.

[0012] A fifth aspect of the present invention is a resin composition comprising the polymer according to any one of the first to third aspects and a polyester resin.

[0013] A sixth aspect of the present invention is the resin composition according to the fifth aspect, wherein the polyester resin comprises an aliphatic polyester.

[0014] A seventh aspect of the present invention is the resin composition according to the fifth or sixth aspect, wherein the polyester resin contains a polyester having a structural unit derived from a hydroxycarboxylic acid having 2 to 30 carbon atoms.

[0015] An eighth aspect of the present invention is the resin composition according to any one of the fifth to seventh aspects, wherein the polyester resin contains a polyester having a structural unit derived from polylactic acid.

[0016] A ninth aspect of the present invention is a molded article made of the resin composition according to any one of the fifth to eighth aspects.

[0017] A tenth aspect of the present invention is a foam-molded article obtained by foam-molding the resin composition according to any one of the fifth to eighth aspects. [Effects of the Invention]

[0018] The polymer according to one embodiment of the present invention can be used in a wide range of molding methods, and can provide a resin composition that exhibits high surface smoothness and a high expansion ratio when subjected to foam molding, and a molded article made from the resin composition. Therefore, the polymer, a resin additive containing the polymer, and a resin composition containing the polymer and a polyester resin can be applied to various molding conditions, molding means, molding devices, etc., and can be said to be industrially advantageous. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described in detail below. However, the present invention is not limited to this, and various modifications are possible within the scope of the description. For example, embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A and less than or equal to B."

[0020] [Embodiment 1: Polymer] A polymer according to one embodiment of the present invention is a polymer containing a structural unit derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms and a structural unit derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms.

[0021] As shown in the examples described below, the polymer can significantly improve the melt tension of a resin composition containing the polymer and a polyester resin, compared to a resin composition not containing the polymer. Therefore, the moldability of the resin composition can be improved, and stable molding can be performed even when the resin composition is subjected to foam molding. As a result, compared to a resin composition not containing the polymer, the expansion ratio can be significantly improved and a molded product with excellent surface smoothness can be obtained.

[0022] The structural unit derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms is a structural unit represented by the following formula (1).

[0023] [ka]

[0024] (wherein R1 is an alkyl group having less than 6 carbon atoms). The structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group with 6 or more carbon atoms is a structural unit represented by the following formula (2): Hereinafter, this structural unit will be referred to as structural unit B.

[0025] [ka]

[0026] (wherein R2 is an alkyl group having 6 or more carbon atoms, and R3 is a hydrogen atom or a methyl group.) The content of the structural unit A in 100% by mass of the polymer is preferably from 30 to 99% by mass, more preferably from 35 to 98% by mass, even more preferably from 40 to 96% by mass, and particularly preferably from 50 to 95% by mass.

[0027] By setting the content of the structural unit A to 30% by mass or more, in a resin composition containing the polymer and a polyester resin, the dispersibility of the polymer in the polyester resin is improved, and the smoothness of a molded product is improved. Furthermore, by setting the content to 99% by mass or less, the effect of improving the melt tension of the resin composition and the effect of improving the expansion ratio during expansion molding of the resin composition are easily obtained.

[0028] Examples of the alkyl methacrylate ester having an alkyl group having less than 6 carbon atoms include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, sec-pentyl methacrylate, 3-pentyl methacrylate, and neopentyl methacrylate. Among these, the alkyl methacrylate ester is preferably an alkyl methacrylate ester having an alkyl group having less than 5 carbon atoms, more preferably an alkyl methacrylate ester having an alkyl group having less than 3 carbon atoms, and most preferably methyl methacrylate. These alkyl methacrylate esters may be used alone or in combination depending on the purpose.

[0029] The content of the structural unit B in 100% by mass of the polymer is preferably from 1 to 70% by mass, more preferably from 2 to 65% by mass, even more preferably from 4 to 60% by mass, and particularly preferably from 5 to 50% by mass.

[0030] By setting the content to 1% by mass or more, it is possible to improve the melt tension of a resin composition containing the polymer and a polyester resin, and to improve the expansion ratio during expansion molding of the resin composition. Furthermore, by setting the content to 70% by mass or less, the dispersibility of the polymer in the polyester resin in the resin composition is improved, and the smoothness of the molded product is improved.

[0031] Examples of the (meth)acrylic acid alkyl ester having an alkyl group having 6 or more carbon atoms include n-hexyl (meth)acrylate, iso-hexyl (meth)acrylate, neohexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, cycloheptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. Among these, the (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 8 or more carbon atoms, more preferably a (meth)acrylic acid alkyl ester having an alkyl group having 10 or more carbon atoms, even more preferably a (meth)acrylic acid alkyl ester having an alkyl group having 12 or more carbon atoms, and most preferably stearyl (meth)acrylate. These (meth)acrylic acid alkyl esters may be used alone or in combination depending on the purpose.

[0032] The upper limit of the number of carbon atoms in the alkyl group of the (meth)acrylic acid alkyl ester is preferably 30 or less, and more preferably 24 or less, from the viewpoint of dispersibility of the polymer in the polyester resin.

[0033] The polymer can be obtained, for example, by copolymerizing an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms, an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms, and optionally other monomers.

[0034] Examples of the other monomers include alkyl acrylates having an alkyl group having 1 to 5 carbon atoms; (meth)acrylic esters having an aromatic substituent such as benzyl (meth)acrylate and phenyl (meth)acrylate; aromatic vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; and acid anhydrides such as maleic anhydride, but the monomers are not limited to these specific examples.

[0035] The other monomers may be used alone or in combination of two or more depending on the purpose. The content of the structural units derived from the other monomers in 100% by mass of the polymer is preferably 0 to 30% by mass. When the polymer contains structural units derived from other monomers, the total content of the structural unit A, the structural unit B, and the structural units derived from the other monomers is 100% by mass.

[0036] By setting the content of structural units derived from other monomers to 30% by mass or less, it is possible to easily obtain the effect of improving the melt tension of a resin composition containing the polymer and a polyester resin, and the effect of improving the expansion ratio during foam molding of the resin composition.

[0037] The polymer may include a polymer obtained by using a polyfunctional monomer such as divinylbenzene, allyl methacrylate, 1,3-butylene dimethacrylate, or triallyl cyanurate as the other monomer. In this case, the content of structural units derived from the polyfunctional monomer in 100% by mass of the polymer is preferably 2.0% by mass or less, and more preferably 1.0% by mass or less. By keeping the content at 2.0% by mass or less, it is possible to easily obtain the effect of improving the melt tension of a resin composition containing the polymer and a polyester resin, and the effect of improving the expansion ratio during expansion molding of the resin composition.

[0038] The mass average molecular weight of the polymer is not particularly limited, but from the viewpoint of obtaining an excellent effect of improving melt tension when molding the resin composition and an effect of improving the expansion ratio when foam molding the resin composition, it is preferable to adjust the mass average molecular weight within an appropriate range. That is, the mass average molecular weight is preferably 100,000 to 10,000,000, more preferably 300,000 to 9,000,000, even more preferably 500,000 to 8,500,000, even more preferably 1,500,000 to 8,000,000, and most preferably 3,000,000 to 8,000,000.

[0039] The mass average molecular weight can be adjusted by a commonly used method such as adjusting the amount of a chain transfer agent used when preparing the polymer, adjusting the amount of a polymerization initiator used, or adjusting the polymerization temperature.

[0040] By setting the mass average molecular weight to 100,000 or more, the effect of improving the melt tension of the resin composition and the effect of improving the expansion ratio during foam molding of the resin composition can be easily obtained. Furthermore, by setting the mass average molecular weight to 10,000,000 or less, an excessive increase in the melt tension-imparting effect can be suppressed. At the same time, the dispersibility of the polymer in the polyester resin in the resin composition is improved, thereby improving the appearance of the molded product.

[0041] The mass average molecular weight can be measured by gel permeation chromatography (GPC). When measuring by GPC, it is preferable to use tetrahydrofuran (THF) as an eluent and to use a molecular weight converted using polystyrene as a standard polymer. It is also preferable to use a separation column having an exclusion limit molecular weight 20 times or more the mass average molecular weight to be measured.

[0042] The glass transition temperature of the polymer is not particularly limited, but is preferably 0° C. to 120° C., more preferably 40° C. to 115° C., even more preferably 60° C. to 110° C., and most preferably 80° C. to 105° C. Hereinafter, the glass transition temperature may be referred to as "Tg value."

[0043] When the Tg value of the polymer is 0°C or higher, the polymer has excellent handleability as a powder, and in the resin composition, the polymer has good dispersibility in the polyester resin, thereby improving the appearance of the molded product.

[0044] The Tg value of the polymer can be calculated using the FOX formula. In this case, the Tg value of each homopolymer obtained by polymerizing each monomer unit constituting the polymer can be, for example, the value described in "POLYMER HANDBOOK" (Wiley Interscience, 1999). Furthermore, the Tg value of a monomer component not described can be calculated using Bicerano's method "Prediction of Polymer Properties" (Marcel Dekker, 2002).

[0045] The polymer can be produced by, for example, emulsion polymerization, soap-free polymerization, microsuspension polymerization, or the like. Emulsion polymerization involves dissolving an emulsifier or surfactant in water as a medium, adding a water-insoluble or poorly soluble monomer, and polymerizing the resulting mixture using a water-soluble polymerization initiator. Soap-free polymerization involves using a reaction system containing a monomer, an ionic polymerization initiator, and water, in which ionic radicals generated by dissolving the ionic polymerization initiator in water are reacted with the monomer dissolved in the aqueous phase to obtain a high molecular weight product. Microsuspension polymerization involves using water as a dispersion medium, emulsifying and dispersing a mixture of monomer, surfactant, oil-soluble polymerization initiator, etc. into fine droplets using a homogenizer or the like, and then polymerizing the resulting mixture. Microsuspension polymerization is also known as suspension polymerization.

[0046] The polymer can be obtained, for example, by the following method. That is, when emulsion polymerization or soap-free polymerization is used, the polymer (polymer latex) obtained by the polymerization method is cooled, and then the polymer is coagulated or salted out with an acid or electrolyte to precipitate, followed by filtration, washing, and drying. The acid can be one or more acids such as sulfuric acid, hydrochloric acid, and phosphoric acid. The electrolyte can be one or more electrolytes selected from the group consisting of aluminum chloride, calcium chloride, magnesium sulfate, aluminum sulfate, and calcium acetate. Various drying methods such as spray drying and freeze drying can be used. When producing the polymer by a microsuspension method, the polymer component can be recovered by filtration from the obtained polymer dispersion, washed, and dried to obtain the polymer.

[0047] [Embodiment 2: Resin Additive] A resin additive according to one embodiment of the present invention includes the polymer according to one embodiment of the present invention, and may contain components other than the polymer, provided that the object of the present invention is not impaired. Examples of such components include one or more components selected from the group consisting of other components that may be contained in the resin composition according to one embodiment of the present invention, which will be described later, inorganic salts that improve powder flowability when used as a resin additive, and fumed silica.

[0048] The content of the polymer in the resin additive is not particularly limited, but may be 100% by mass, preferably 50 to 100% by mass, and more preferably 80 to 100% by mass, relative to 100% by mass of the resin additive. By setting the content to 50% by mass or more, it is possible to effectively obtain the effect of improving the melt tension when a resin composition containing the resin additive and a polyester resin is prepared, and the effect of improving the expansion ratio when the resin composition is foam-molded.

[0049] [Embodiment 3: Resin composition] A resin composition according to one embodiment of the present invention contains the polymer according to one embodiment of the present invention and a polyester resin.

[0050] The resin composition contains the polymer, and therefore has a superior melt tension compared to a resin composition not containing the polymer, making the resin composition suitable for a wide range of molding methods, and particularly when applied to foam molding, it can exhibit high surface smoothness and a high expansion ratio.

[0051] The polymer is as described in embodiment 1. The polyester resin preferably contains an aliphatic polyester. The aliphatic polyester is a polymer having an ester bond in the molecule, and is obtained by polycondensation of a hydroxycarboxylic acid or polycondensation of a dicarboxylic acid component and a diol component. These polymers may be used alone, or two or more polymers may be used. The aliphatic polyester more preferably contains a polycondensate of a hydroxycarboxylic acid, since this has excellent foam moldability, and particularly preferably contains a polyester having a structural unit derived from polylactic acid.

[0052] <Hydroxycarboxylic acid> When the hydroxycarboxylic acid is used as a raw material for the polyester resin, the polyester resin preferably contains a polyester having a structural unit derived from a hydroxycarboxylic acid having 2 to 30 carbon atoms. There are no particular restrictions on the type of hydroxycarboxylic acid, but the hydroxycarboxylic acid more preferably has 2 to 20 carbon atoms, and even more preferably has 2 to 10 carbon atoms.

[0053] Specific examples of hydroxycarboxylic acids include glycolic acid, lactic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, hydroxyhexanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, leucinic acid, and silinolic acid. Among these, lactic acid and glycolic acid are more preferred due to their excellent foaming moldability, and lactic acid is particularly preferred. In other words, it is particularly preferred that the polyester resin contains a polyester having structural units derived from polylactic acid. One or more of the hydroxycarboxylic acids may be used.

[0054] <Dicarboxylic acid> When the dicarboxylic acid is used as a raw material for the polyester resin, the type thereof is not particularly limited.Specific examples include aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, and ethylmalonic acid; alicyclic dicarboxylic acids such as adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, and 9,9'-bis(4-carboxyphenyl)fluorene acid, or ester derivatives thereof. The dicarboxylic acids may be used alone or in combination of two or more.

[0055] <Diol> When the diol is used as a raw material for the polyester resin, the type thereof is not particularly limited. For example, aliphatic diols such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, hexanediol, and neopentyl glycol; saturated alicyclic primary diols such as cyclohexanedimethanol, cyclohexanediethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, and decalindiethanol; 2,6-dihydroxy-9-oxabicyclo[3,3,1]nonane, 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetramethyl ... Examples of the diol include saturated heterocyclic primary diols containing cyclic ethers, such as tetraoxaspiro[5,5]undecane (spiroglycol), 5-methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, and isosorbide; alicyclic diols such as cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxycyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, and adamantanediol; and aromatic diols such as paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, and 9,9'-bis(4-hydroxyphenyl)fluorene. In addition to the diol, polyfunctional alcohols such as trimethylolpropane and pentaerythritol can also be used as long as they do not cause gelation. One or more of the diols may be used.

[0056] Among these, from the viewpoint of the heat resistance and hydrolysis resistance of the resin composition, one or more diols selected from the group consisting of ethanediol, propanediol, and butanediol are preferred.

[0057] The weight average molecular weight of the polyester resin is not particularly limited, but is preferably from 30,000 to 500,000, more preferably from 50,000 to 400,000, and even more preferably from 80,000 to 300,000. By setting the weight average molecular weight to 30,000 or more, it becomes easier to obtain a good foamed molded article. Furthermore, by setting the weight average molecular weight to 500,000 or less, the molding processability of the resin composition can be improved.

[0058] The content of the polymer in the resin composition is preferably 0.1 to 200 parts by mass, more preferably 0.5 to 200 parts by mass, even more preferably 1 to 200 parts by mass, and particularly preferably 3 to 150 parts by mass, per 100 parts by mass of polyester resin. By setting the content to 0.1 parts by mass or more, the effect of improving the melt tension of the resin composition and the effect of improving the expansion ratio during foam molding of the resin composition can be obtained. Furthermore, by setting the content to 200 parts by mass or less, the dispersibility of the polymer in the polyester resin in the resin composition can be improved, thereby improving the appearance of the molded product.

[0059] The melt tension of the resin composition varies depending on the intended use, but from the viewpoint of obtaining sufficient moldability, for example, it is preferably 12 mN or more, more preferably 40 mN or more, even more preferably 60 mN or more, even more preferably 80 mN or more, and particularly preferably 100 mN or more.

[0060] The upper limit of the melt tension of the resin composition is not particularly limited, but it is preferably 2000 mN or less from the viewpoint of preventing breakage during high-speed molding.

[0061] The melt tension can be measured by the method described in the examples below.

[0062] The expansion ratio of the resin composition during expansion molding varies depending on the intended use, but is preferably 1.20 times or more, and more preferably 1.25 times or more, from the viewpoint of reducing the weight of the molded article. The upper limit of the expansion ratio is not particularly limited, but is preferably 100 times or less, from the viewpoint of the strength of the molded article. The expansion ratio can be measured by the method described in the Examples below.

[0063] The resin composition may contain other components in addition to the polyester resin and the polymer, provided that the object of the present invention is not impaired. Examples of such other components include one or more selected from the group consisting of a foaming agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, a flame retardant, an impact strength modifier, a catalyst deactivator, a plasticizer, a lubricant, a mold release agent, an antistatic agent, an antibacterial agent, an antifogging agent, a filler, a crystal nucleating agent, and a pigment.

[0064] Examples of the heat stabilizer and / or the antioxidant include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, and alkali metal halides.

[0065] The foaming agent may be a volatile foaming agent and / or a thermal decomposition type foaming agent.

[0066] Examples of the volatile blowing agent include carbon dioxide, nitrogen, water, hydrocarbons such as ethane, butane, pentane, hexane, and heptane, and halogenated hydrocarbons such as methyl chloride, monochlorotrifluoromethane, dichlorofluoromethane, and dichlorotetrafluoromethane. These volatile blowing agents may be used alone or in combination of two or more. Among these, carbon dioxide and nitrogen are most preferred in terms of safety, environmental impact, and ease of obtaining a supercritical state.

[0067] The volatile foaming agent is preferably used in an amount ranging from 0.1 to 10 parts by mass relative to 100 parts by mass of the resin composition. By setting the content of the volatile foaming agent to 0.1 part by mass or more, the foaming ratio can be easily improved. Furthermore, by setting the content to 10 parts by mass or less, gas escape during foaming can be reduced, which makes it easier to improve the surface smoothness of molded articles.

[0068] The thermally decomposable foaming agent may be a thermally decomposable inorganic foaming agent and / or a thermally decomposable organic foaming agent. Examples of the thermally decomposable inorganic foaming agent include sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate. Examples of the thermally decomposable organic foaming agent include nitroso compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosoterephthalamide; azo compounds such as azodicarbonamide (ADCA) and azobisisobutyronitrile; and sulfonylhydrazide compounds such as benzenesulfonylhydrazide and toluenesulfonylhydrazide.

[0069] These thermally decomposable foaming agents may be used alone or in combination of two or more. The content of the thermally decomposable foaming agent is preferably 0.1 to 10 parts by mass in total relative to 100 parts by mass of the resin composition. By setting the content of the thermally decomposable foaming agent to 0.1 part by mass or more, the effect of improving the expansion ratio is likely to be obtained. Furthermore, by setting the content to 10 parts by mass or less, gas escape during foaming can be reduced, which makes it easy to improve the surface smoothness of the molded product.

[0070] When a thermally decomposable organic foaming agent is used, a foaming accelerator called a kicker may be added to match the decomposition temperature with the processing temperature. Examples of the foaming accelerator include one or more selected from metal compounds having Lewis acid properties, such as zinc stearate, zinc oxide, zinc carboxylate, cadmium stearate, calcium stearate, potassium perchlorate, sodium perchlorate, calcium perchlorate, magnesium perchlorate, barium perchlorate, and zinc perchlorate.

[0071] The flame retardant may be one or more selected from the group consisting of halogen-based flame retardants, phosphorus-based flame retardants, and inorganic flame retardants, but it is preferable to use a non-halogen flame retardant. Examples of the non-halogen flame retardant include phosphorus-based flame retardants, hydrated metal compounds (aluminum hydroxide, magnesium hydroxide), N-containing compounds (melamine-based, guanidine-based), and inorganic compounds (borates, Mo compounds).

[0072] Examples of the catalyst deactivator include alkyl phosphate and / or alkyl phosphonate compounds, such as one or more compounds selected from the group consisting of monooctyl phosphate, dioctyl phosphate, monoethylhexyl phosphate, diethylhexyl phosphate, monostearyl phosphate, and distearyl phosphate.

[0073] The filler may be an inorganic filler or an organic filler, and examples of the inorganic filler include at least one selected from the group consisting of talc, calcium carbonate, zinc carbonate, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloons, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, boron nitride, and graphite.

[0074] Examples of the organic filler include naturally occurring polymers such as one or more selected from the group consisting of starch, cellulose fine particles, wood flour, soybean pulp, rice husks, and bran, as well as modified products thereof.

[0075] The nucleating agent may be inorganic or organic. Examples of the inorganic nucleating agent include talc and / or kaolin. The organic nucleating agent may be one or more selected from the group consisting of sorbitol compounds, benzoic acid, metal salts of these compounds, metal phosphate esters, and rosin compounds, as needed.

[0076] The resin composition can be produced by mixing the polymer, the polyester resin, and, if necessary, the other components. The method for performing the mixing is not particularly limited, and known methods can be used.

[0077] [Embodiment 3: Molded body] A molded article according to one embodiment of the present invention is made from the resin composition according to one embodiment of the present invention. Because the resin composition contains the polymer, the melt tension is improved compared to a resin composition that does not contain the polymer. Therefore, the resin composition has excellent moldability. The molded article can be obtained by molding the resin composition, and can accurately have the intended shape. The molding method is not particularly limited. For example, various molding methods such as extrusion molding, injection molding, blow molding, and vacuum molding can be used.

[0078] The melt tension is an index of moldability in molding methods in which a resin deforms while maintaining a free surface, such as foam molding, blow molding, inflation molding, cast molding, and spinning molding. If the melt tension is low, problems such as bubbles easily breaking in foam molding and poor drawdown properties of the resin in inflation molding may occur, but the resin composition has excellent melt tension, and therefore the molded article does not have such problems.

[0079] Therefore, the molded article is preferably one molded using the molding method such as foam molding, blow molding, etc. In particular, since the resin composition can provide high surface smoothness and a high expansion ratio when applied to foam molding, the molded article is more preferably a foam molded article obtained by foam molding the resin composition.

[0080] The foam molding method is not particularly limited, and may be solid phase foaming or liquid phase foaming. Examples of solid phase foaming that can be used include bead foaming, batch foaming, press foaming, and atmospheric secondary foaming. Examples of liquid phase foaming that can be used include extrusion foaming, injection foaming, and foam blowing. A foam molded article according to one embodiment of the present invention can be produced by subjecting the resin composition to any of these foam molding methods.

[0081] A method for producing a foamed molded article using the volatile foaming agent includes a step of impregnating the resin composition with a gas and / or a supercritical fluid, and a step of degassing the resin composition to foam it.

[0082] Examples of such methods include a method in which a gas and / or supercritical fluid is sealed in a sealed autoclave, the resin composition is impregnated with the gas and / or supercritical fluid for a certain period of time, and then the pressure in the autoclave is released to cause foaming; a method in which the resin composition is placed in a melt extruder, the gas and / or supercritical fluid is injected into the middle of the cylinder, the gas and / or supercritical fluid is impregnated using the pressure inside the cylinder, and foaming is performed at the die outlet of the extruder, etc. Among these, the method in which the resin composition is impregnated with the supercritical fluid using an extruder or the like, and then extruded through a die to cause foaming is preferred from the viewpoint of excellent continuous productivity.

[0083] The gas also includes liquefied gas, and examples of the gas include the volatile blowing agents exemplified above. The supercritical fluid can be obtained, for example, by placing carbon dioxide and / or nitrogen at a temperature equal to or higher than the critical temperature and at a pressure equal to or higher than the critical pressure.

[0084] The extruder may be a single-screw extruder, a twin-screw extruder, a tandem extruder, or the like. The tandem extruder may be any of an extruder combining a single-screw extruder and a single-screw extruder, an extruder combining a twin-screw extruder and a single-screw extruder, or an extruder combining a twin-screw extruder and a twin-screw extruder. Among these, when a resin composition containing a polyester having structural units derived from polylactic acid is to be supplied, it is most preferable to use the tandem extruder. If necessary, a gear pump or the like may be installed between the extruder and the die.

[0085] The uses of the molded articles and foamed molded articles are not particularly limited, and examples thereof include interior and exterior automotive parts such as instrument panels, door trims, sun visors, side sill protectors, and side garnishes; automotive parts such as engine covers, shock absorbing pads, and air ducts; food containers and packaging materials such as cups, trays, cap seals, and beverage bottles; transport and packaging materials such as cushioning materials and polystyrene foam boxes; parts for the electrical, electronic, and electric wire fields such as reflective films and electric wire covering materials; and building materials such as heat insulation materials and tatami mats.

[0086] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Example]

[0087] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In each example and comparative example, "parts" means "parts by mass," and evaluations were performed according to the following measurement methods.

[0088] <Measurement method> (1) Mass average molecular weight The tetrahydrofuran (THF) soluble fraction of the polymer according to one embodiment of the present invention was used as a sample and subjected to molecular weight measurement using gel permeation chromatography (GPC). The GPC measurement conditions are as follows, and the mass average molecular weight was determined from a calibration curve using standard polystyrene. Equipment: Tosoh Corporation "HLC8320" Column: Tosoh Corporation "TSKgel GMHHR-H(20)" (inner diameter 7.8 mm x length 30 cm, exclusion limit 4 x 10 8 Da (estimated) Eluent:THF Eluent flow rate: 0.600ml / min Measurement temperature: 40℃ Detector: Differential refractometer (RI) Sample injection volume: 10 μl (sample concentration 1000 μg / mL).

[0089] (2) Melt tension The melt tension was evaluated as an index of melt strength. Since an improvement in melt tension can be regarded as an improvement in melt strength, a higher melt tension value is preferable.

[0090] The melt tension was measured as follows.

[0091] The polyester resin composition was extruded at a constant rate using a capillary rheometer, and the strand was taken up at a constant rate. Equipment: ROSAND "Twin Capillary Rheometer RH-7" Die: length 16.0mm, diameter φ1.0mm Temperature: 200℃ Extrusion speed: 2 m / min (piston speed: 8.89 mm / min) Take-up speed: 20m / min.

[0092] (3) Expansion Ratio To evaluate the foam moldability, the expansion ratio was measured.

[0093] The expansion ratio was calculated by the following formula (A). Foaming ratio = d0 / d1 Formula (A) d0: Density of non-foamed molded body extruded from polyester resin alone (no foaming agent added) d1: Density of foamed molded article of resin composition (containing foaming agent).

[0094] The d0 and d1 were measured by the underwater displacement method using a "DENSHIMETER-H" manufactured by Toyo Seiki Seisakusho Co., Ltd. as the measuring device.

[0095] (4) Surface smoothness The surface smoothness of a 10 cm long foam-molded product was visually observed and judged according to the following criteria. +++: No traces of broken bubbles or irregularities are observed on the surface of the foam-molded product. ++: No traces of broken bubbles on the surface of the foam-molded product, but irregularities are observed +: No traces of broken bubbles on the surface of the foam-molded product, but irregularities and wrinkles are observed -: There are traces of broken bubbles on the surface of the foam-molded product, and many irregularities are observed. Surface smoothness improves in the order of +++, ++, +, and -. ++ or +++ can be said to be sufficiently excellent in surface smoothness.

[0096] [Production Example 1] Production of polymer (B-1) 220 parts of ion-exchanged water, 4 parts of dipotassium alkenyl succinate (Latemul ASK, manufactured by Kao), 80 parts of methyl methacrylate, and 20 parts of n-stearyl acrylate were weighed into a beaker. Next, these were stirred at 10,000 rpm for 3 minutes per 1 L of the weighed solution using an IKA Homogenizer T25 to obtain a pre-emulsified dispersion. The obtained pre-emulsified dispersion was charged into a reaction vessel equipped with a stirrer and a reflux condenser, and the atmosphere inside the vessel was replaced with nitrogen. The contents of the reaction vessel were then heated to 50°C while stirring, and 0.15 parts of potassium persulfate was added to initiate the polymerization reaction. The mixture was then heated and stirred for 4 hours. The contents were then cooled to 20°C to terminate the polymerization, yielding an emulsion of the polymer (B-1).

[0097] The resulting emulsion of (B-1) was poured into a vessel containing 600 parts by mass of a 5% aqueous calcium acetate solution heated to 50°C over a period of 3 minutes while stirring, and then heated to 95°C and held for 5 minutes. The mixture was then filtered, washed, and dried to obtain a powdered polymer (B-1).

[0098] The methyl methacrylate forms, in the polymer, structural units derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms. The n-stearyl acrylate forms, in the polymer, structural units derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms. The dipotassium alkenyl succinate is an emulsifier for emulsion polymerization.

[0099] [Production Examples 2 to 5] Production of polymers (B-2) to (B-5) Polymerization was carried out in the same manner as in Production Example 1, except that the raw materials used were changed as shown in Table 1, to obtain polymers (B-2) to (B-5).

[0100] [Production Examples 6 to 11] Production of polymers (B-6) to (B-11) Polymers (B-6) to (B-11) were obtained by carrying out polymerization in the same manner as in Production Example 1, except that the raw materials used were changed as shown in Table 1 and the amount of potassium persulfate was changed to 0.08 parts.

[0101] Table 1 shows the raw material compositions of the polymers (B-1) to (B-11).

[0102] [Table 1]

[0103] In the table, B-1 to B-11 represent the polymers (B-1) to (B-11), MMA represents methyl methacrylate, EMA represents ethyl methacrylate, nSA represents n-stearyl acrylate, nDA represents n-lauryl acrylate, nOA represents n-octyl acrylate, MA represents methyl acrylate, and nBA represents n-butyl acrylate.

[0104] Example 1 100 parts of polylactic acid (Luminy LX-175, manufactured by Total Corbion) as a polyester resin and 10 parts of the polymer (B-1) were mixed to obtain a polyester resin composition. The obtained polyester resin composition was fed into a Φ30 mm co-rotating twin-screw extruder (die: Φ2 mm × 4 holes), extruded under the following conditions, and pelletized to obtain polyester resin composition pellets. The obtained polyester resin composition pellets were subjected to evaluation of melt tension.

[0105] (Extrusion conditions) Temperature: 170℃-180℃-190℃-200℃-200℃-200℃(C1-C2-C3-C4-HD) Screw rotation speed: 250 rpm.

[0106] The C1 to C4 are temperature setting points of the extruder, with C1 being the hopper side of the extruder screw and C4 being the head side, and the equally spaced points between them are C2 and C3 from the C1 side. H denotes the head part, and D denotes the die.

[0107] Table 2 shows the types and amounts of polyester resins and polymers used, as well as the results of measuring the melt tension of the polyester resin composition pellets.

[0108] [Examples 2 to 4], [Comparative Examples 1 to 3] Extrusion was carried out in the same manner as in Example 1, except that the type and amount of polymer used were changed as shown in Table 2, to obtain pellets of each polyester resin composition, and the melt tension thereof was measured.

[0109] [Table 2]

[0110] In the table, B-12 is polymer (B-12), which is an acrylic processing aid P-530A (manufactured by Mitsubishi Chemical Corporation, methyl methacrylate-n-butyl acrylate copolymer, mass average molecular weight 3.3 million).

[0111] As shown in Table 2, the resin compositions of Examples 1 to 4 exhibited significantly higher melt tensions than the polylactic acid of Comparative Example 1, which did not contain a polymer. The resin composition of Comparative Example 2 did not contain "structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group with 6 or more carbon atoms," but was superior to Example 4 in terms of melt tension alone. However, as shown in Comparative Example 5, which will be described later, the foamed molded article obtained using the resin composition of Comparative Example 2 had insufficient expansion ratio and surface smoothness. Furthermore, the commercially available resin composition of Comparative Example 3, which did not contain "structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group with 6 or more carbon atoms," was insufficient in all of melt tension, expansion ratio, and surface smoothness.

[0112] Therefore, since the polymers used in Examples 1 to 4 have a configuration according to one embodiment of the present invention, they are excellent in the effect of improving the melt tension (melt strength) of the resin composition, and are also excellent in the effect of improving the foaming ratio and surface smoothness of the resin composition, as will be described later.

[0113] Example 5 A polyester resin composition was obtained by mixing 100 parts of polylactic acid (Luminy LX-175, manufactured by Total Corbion, optical purity 96%L) as a polyester resin with 10 parts of the polymer (B-1). The obtained polyester resin composition was fed into a Φ30 mm co-rotating twin-screw extruder (die: Φ2 mm × 4 holes), extruded under the following conditions, and pelletized to obtain polyester resin composition pellets. The meanings of C1 to C4, H, and D below are as described in Example 1.

[0114] (Extrusion conditions) Temperature: 170℃-180℃-190℃-200℃-200℃-200℃(C1-C2-C3-C4-HD) Screw rotation speed: 250 rpm.

[0115] 110 parts of the obtained polyester resin composition pellets and 2 parts of azodicarbonamide (ADCA) were mixed, fed into a Φ25 mm single-screw extruder (die: Φ5 mm round bar), and extrusion-molded under the following conditions to obtain a polyester resin foam molded article. The meanings of C1 to C2 and D below are as described in Example 1.

[0116] (Extrusion conditions) Temperature: 190℃-210℃-230℃-210℃(C1-C2-C3-D) Screw rotation speed: 30 rpm.

[0117] Table 3 shows the measurement results of the expansion ratio and surface smoothness of the polyester resin expansion molded article.

[0118] [Examples 6 to 8], [Comparative Examples 4 to 6] Extrusion was carried out in the same manner as in Example 5, except that the type and amount of polymer used were changed as shown in Table 3, to obtain each polyester resin foam molded article, and the expansion ratio and surface smoothness were measured.

[0119] [Table 3]

[0120] As shown in Table 3, the polyester resin foam molded articles of Examples 5 to 8 had higher expansion ratios and better surface smoothness than the polyester resin foam molded articles of Comparative Examples 4 to 6. As mentioned above, the polyester resin composition used as the raw material for the polyester resin foam molded article of Comparative Example 5 exceeded that of Example 4 in terms of melt tension alone (Table 2), but as shown in Table 3, the expansion ratio and surface smoothness were insufficient.

[0121] [Examples 9 to 13, Comparative Examples 7 to 11] Extrusion was carried out in the same manner as in Example 1, except that the type of polyester resin was changed to polylactic acid (Luminy L-175, manufactured by Total Corbion, optical purity >99%L) and the type of polymer used was changed as shown in Table 4, to obtain pellets of each polyester resin composition, and their melt tensions were measured.

[0122] [Table 4]

[0123] As shown in Table 4, the resin compositions of Examples 9 to 13 exhibited higher melt tensions than those of Comparative Example 7, which did not contain a polymer, and the resin compositions of Comparative Examples 8 to 11, which used polymers that did not contain "structural units derived from (meth)acrylic acid alkyl esters having an alkyl group having 6 or more carbon atoms."

[0124] Therefore, since the polymers used in Examples 9 to 13 have a configuration according to one embodiment of the present invention, they are excellent in the effect of improving the melt tension (melt strength) of the resin composition, and as will be described later, are also excellent in the effect of improving the foaming ratio and surface smoothness of the resin composition.

[0125] [Examples 14 to 18], [Comparative Examples 12 to 16] Extrusion was carried out in the same manner as in Example 5, except that the type of polyester resin was changed to polylactic acid (Luminy L-175, manufactured by Total Corbion, optical purity >99%L) and the type of polymer used was changed as shown in Table 5, to obtain each polyester resin foam molded product, and the expansion ratio and surface smoothness were measured.

[0126] [Table 5]

[0127] As shown in Table 5, the polyester resin expansion molded articles of Examples 14 to 18 had higher expansion ratios and were superior in surface smoothness compared to the polyester resin expansion molded articles of Comparative Examples 12 to 16.

[0128] [Examples 19 to 21, Comparative Examples 17 to 19] Extrusion was carried out in the same manner as in Example 1, except that the type of polyester resin was changed to polylactic acid (Luminy L-175, manufactured by Total Corbion, optical purity >99%L) and the type and amount of polymer used were changed as shown in Table 6. Pellets of each polyester resin composition were obtained, and their melt tensions were measured.

[0129] [Table 6]

[0130] As shown in Table 6, the resin compositions of Examples 19 to 21 exhibited higher melt tensions than the resin compositions of Comparative Examples 17 to 19 using polymers that did not contain "structural units derived from (meth)acrylic acid alkyl esters having an alkyl group with 6 or more carbon atoms."

[0131] Therefore, since the polymers used in Examples 19 to 21 have a configuration according to one embodiment of the present invention, they are excellent in the effect of improving the melt tension (melt strength) of the resin composition, and as will be described later, are also excellent in the effect of improving the foaming ratio and surface smoothness of the resin composition.

[0132] [Examples 22 to 24], [Comparative Examples 20 to 22] Extrusion was carried out in the same manner as in Example 5, except that the type of polyester resin was changed to polylactic acid (Luminy L-175, manufactured by Total Corbion, optical purity >99%L) and the type and amount of polymer used were changed as shown in Table 7. Each polyester resin foam molded product was obtained, and the expansion ratio and surface smoothness were measured.

[0133] [Table 7]

[0134] As shown in Table 7, the polyester resin expansion molded articles of Examples 22 to 24 had higher expansion ratios and better surface smoothness than the polyester resin expansion molded articles of Comparative Examples 20 to 22.

[0135] Therefore, it can be said that a polymer having a configuration according to one embodiment of the present invention is excellent in the effect of improving the melt tension (melt strength) of a resin composition, and is also excellent in the effect of improving the foaming ratio and surface smoothness of a resin composition. [Industrial Applicability]

[0136] The present invention can be used in a wide range of fields, such as the automobile industry, food containers and packaging materials, transport materials and packaging materials, etc.

Claims

1. A polymer containing a structural unit derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms and a structural unit derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms.

2. The polymer according to claim 1 , wherein the alkyl group of the (meth)acrylic acid alkyl ester having an alkyl group having 6 or more carbon atoms has 8 or more carbon atoms.

3. 2. The polymer according to claim 1, wherein the content of the structural units derived from an alkyl methacrylate ester having an alkyl group with less than 6 carbon atoms is 30 to 99 mass%, and the content of the structural units derived from an alkyl (meth)acrylate ester having an alkyl group with 6 or more carbon atoms is 1 to 70 mass%, relative to 100 mass% of the polymer.

4. A resin additive comprising the polymer according to any one of claims 1 to 3.

5. A resin composition comprising the polymer according to any one of claims 1 to 3 and a polyester resin.

6. The resin composition according to claim 5 , wherein the polyester resin comprises an aliphatic polyester.

7. The resin composition according to claim 5, wherein the polyester resin comprises a polyester having a structural unit derived from a hydroxycarboxylic acid having 2 to 30 carbon atoms.

8. The resin composition according to claim 5 , wherein the polyester resin comprises a polyester having structural units derived from polylactic acid.

9. A molded article made from the resin composition according to claim 5.

10. A foamed molded article obtained by foam molding the resin composition according to claim 5.

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