Additive for polyamide resin and polyamide resin composition

Abstract

An additive for polyamide resins that includes a first polymer. The first polymer includes, as constituent monomers, (i) a carboxyl group–containing vinyl monomer and (ii) a (meth)acrylic acid ester monomer and / or an aromatic vinyl monomer, and the weight average molecular weight of the first polymer is 2,000–25,000. The additive for polyamide resins may also include a second polymer that has a weight average molecular weight of at least 100,000.

Description

[Technical Field]

[0001] The present invention relates to an additive for polyamide resins and a polyamide resin composition containing the additive. [Background technology]

[0002] Polyamide resins such as nylon-6, nylon-6,6, and nylon-12 have excellent physical properties such as heat resistance and abrasion resistance, and also have excellent resistance to hydrocarbon solvents such as gasoline and oil, so they are used in a variety of molding applications such as machine parts, automobile parts, and electrical and electronic parts.

[0003] However, polyamide resins have the property that their melt viscosity and melt tension drop significantly above their melting point. Therefore, when applied to melt processing methods performed above their melting point, such as blow molding, extrusion molding, and foam molding, molding can be difficult. Specifically, blow molding and extrusion molding can cause the wall thickness of molded products to become non-uniform due to drawdown, and foam molding can cause the cells to become non-uniform.

[0004] Patent Document 1 describes the addition of a thickener (B) to a polyamide resin to increase the melt viscosity of the polyamide resin, which comprises 100 parts by weight of reactive polymer particles (B-1) having a glass transition temperature of 60°C or higher and a volume average particle size of 50 to 500 μm, coated with 0.5 to 30 parts by weight of polymer particles (B-2) having a volume average particle size of 0.01 to 0.5 μm. In the examples, a monomer (glycidyl methacrylate) having an epoxy group is used to produce the polymer particles (B-1), and therefore the polymer particles (B-1) have epoxy groups, and the weight average molecular weight of the polymer particles is disclosed to be 52,000 to 67,000.

[0005] Patent Document 2 does not disclose melt viscosity, but describes the use of 80 to 99 parts by weight of a core-shell polymer and 1 to 20 parts by weight of a copolymer of an alkyl (meth)acrylate and an unsaturated carboxylic acid in combination as an impact modifier for polyamide resins. There is no disclosure of the molecular weight of the copolymer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-31607 [Patent Document 2] Japanese Patent Publication No. 63-61013 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, polyamide resins are required to have improved moldability during melt processing, and at the same time, they are also required to have improved tensile properties of the resulting molded articles. However, the techniques described in Patent Documents 1 and 2 are insufficient to improve moldability during melt processing and further to improve the tensile properties of molded articles.

[0008] In view of the above-described current situation, an object of the present invention is to provide an additive for polyamide resins, which can improve the moldability of polyamide resins during melt processing and can also improve the tensile properties of molded articles containing polyamide resins, and a polyamide resin composition containing the additive. [Means for solving the problem]

[0009] The present inventors discovered that by blending a copolymer containing specific constituent monomers and having an average molecular weight within a specific range with a polyamide resin, the moldability of the polyamide resin during melt processing is improved, and further, the tensile properties of the resulting molded body are improved, leading to the present invention.

[0010] That is, the present invention is an additive for polyamide resins containing a first polymer, wherein the first polymer contains, as a constituent monomer: (i) a carboxyl group-containing vinyl monomer, and (ii) a (meth)acrylic acid ester monomer and / or an aromatic vinyl monomer; The present invention relates to an additive for polyamide resins, which is a copolymer comprising the first polymer and the second polymer, and wherein the first polymer has a weight average molecular weight of 2,000 to 25,000. Preferably, the carboxyl group-containing vinyl monomer accounts for 15% by weight or more and 50% by weight or less of 100% by weight of the first polymer. Preferably, the first polymer is a copolymer containing, as constituent monomers, (i) a carboxyl group-containing vinyl monomer and (ii) a (meth)acrylic acid ester monomer. Preferably, the composition further comprises a second polymer having a weight average molecular weight of 100,000 or more. Preferably, the first polymer forms particles, and at least a portion of the second copolymer is located outside the particles. Preferably, the second polymer is a polymer containing, as a constituent monomer, a methacrylic acid ester monomer and / or an aromatic vinyl monomer. Preferably, the total of the methacrylic acid ester monomer and the aromatic vinyl monomer accounts for 80% by weight to 100% by weight of the second polymer (100% by weight). Preferably, the first polymer and / or the second polymer are non-rubbery polymers. Preferably, the first polymer and the second polymer are each a non-rubber polymer, the first polymer forms particles, and at least a portion of the second polymer is located outside the particles. The present invention also relates to a modifier for polyamide resins, comprising the additive and an impact modifier. Preferably, the impact modifier is a core-shell type impact modifier. Preferably, the impact modifier is a polyolefin elastomer. The present invention further relates to a polyamide resin composition containing a polyamide resin and the additive for polyamide resin, wherein the proportion of the additive is 0.1 to 10% by weight based on 100% by weight of the total of the polyamide resin and the additive; and to a polyamide resin composition containing a polyamide resin and the modifier for polyamide resin, wherein the proportion of the modifier is 1 to 40% by weight based on 100% by weight of the total of the polyamide resin and the modifier. Preferably, the polyamide resin composition further contains a reinforcing material, and the proportion of the reinforcing material is 10 to 60% by weight relative to 100% by weight of the total of the polyamide resin and the reinforcing material. Furthermore, the present invention also relates to pellets or molded articles made from the polyamide resin composition. [Effects of the Invention]

[0011] According to the present invention, there are provided an additive for polyamide resins, which can improve the moldability of polyamide resins during melt processing and the tensile properties of molded articles containing the polyamide resins, and a polyamide resin composition containing the additive. The additive for polyamide resins according to a preferred embodiment of the present invention can reduce the fluidity of polyamide resins during melt processing and can increase the melt viscosity or melt tension of the polyamide resins. Furthermore, the additive for polyamide resins can be blended with an impact modifier into a polyamide resin, thereby further enhancing the impact-improving effect of the impact modifier in addition to the above-mentioned effects. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail.

[0013] (Additives for polyamide resins) The polyamide resin additive of this embodiment contains at least a first polymer. A preferred embodiment of the polyamide resin additive preferably contains a second polymer in addition to the first polymer, since this additive has excellent granulation properties during additive production. The polyamide resin additive is used by blending it with a polyamide resin, and may be a molecular chain extender for the polyamide resin, an agent for improving the moldability of the polyamide resin during melt processing, or an agent for improving the tensile properties of a polyamide resin-containing molded article.

[0014] (first polymer) The first polymer is a copolymer containing, as constituent monomers, a carboxyl group-containing vinyl monomer, and a (meth)acrylic acid ester monomer and / or an aromatic vinyl monomer.

[0015] The first polymer has carboxyl groups derived from the carboxyl group-containing vinyl monomer. When the polyamide resin and the first polymer are mixed by melt kneading or the like, the carboxyl groups of the first polymer can react with the terminal amino groups of the polyamide resin. This reaction elongates the molecular chain of the polyamide resin and can also introduce a branched structure into the polyamide resin. It is presumed that the above mechanism improves the moldability of the polyamide resin during melt processing and further improves the tensile properties of the resulting molded article. On the other hand, as shown in the comparative example below, when a polymer having epoxy groups rather than carboxyl groups was blended with the polyamide resin, the effect of improving the moldability of the polyamide resin during melt processing was not sufficient.

[0016] The carboxyl group-containing vinyl monomer is not particularly limited, but examples thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. One of these may be used alone, or two or more may be used in combination. Among these, acrylic acid and / or methacrylic acid is preferred, and methacrylic acid is more preferred.

[0017] The content of the carboxyl group-containing vinyl monomer can be appropriately set from the viewpoints of the effect of improving moldability during melt processing, the effect of improving the tensile properties of the molded body, productivity, etc. The content may be, for example, 10% by weight or more, based on 100% by weight of the first polymer, but is preferably 15% by weight or more, and more preferably 20% by weight or more. Within this range, the effect of improving moldability during melt processing is particularly excellent. However, if the content of the carboxyl group-containing vinyl monomer is too high, the water content of the first polymer increases, making post-processing during production more complicated. Therefore, the content is preferably 50% by weight or less, and more preferably 45% by weight or less.

[0018] From the viewpoint of productivity, the first polymer contains, as constituent monomers, a (meth)acrylic acid ester monomer and / or an aromatic vinyl monomer in addition to a carboxyl group-containing vinyl monomer. The first polymer preferably contains a (meth)acrylic acid ester monomer because it is effective in improving the moldability of the polyamide resin during melt processing and in improving the tensile properties of the molded article.

[0019] The (meth)acrylic acid ester monomer is not particularly limited, and examples thereof include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate. Among these, (meth)acrylic acid alkyl ester monomers are preferred, (meth)acrylic acid alkyl ester monomers having an alkyl group with 1 to 4 carbon atoms are more preferred, and methyl methacrylate is particularly preferred.

[0020] The aromatic vinyl monomer is not particularly limited, but examples thereof include styrene, α-methylstyrene, p-methylstyrene, etc. Among these, styrene is preferred.

[0021] A larger molecular weight of the first polymer is preferable from the viewpoint of improving moldability during melt processing and the tensile properties of molded articles. Specifically, the weight-average molecular weight of the first polymer is preferably in the range of 2,000 to 25,000, as measured by gel permeation chromatography (GPC) in terms of polystyrene. If the weight-average molecular weight is less than 2,000, the thermal stability of the polymer may be insufficient. If the weight-average molecular weight exceeds 25,000, the stability of the latex during polymer production may decrease, making efficient production difficult. Polymers having a weight-average molecular weight of 25,000 or less can be suitably produced by using a chain transfer agent during polymerization.

[0022] The first polymer is preferably a non-rubber polymer. A non-rubber polymer refers to a polymer that does not have a crosslinked structure between molecular chains. When the first polymer is a non-rubber polymer, the reaction between the carboxyl groups of the first polymer and the terminal amino groups of the polyamide resin proceeds more efficiently, making it easier to achieve improved moldability during melt processing and improved tensile properties of the molded body.

[0023] (Second double combination) The second polymer is an optional component capable of improving granulation properties during production. Because the first polymer has a small molecular weight, powdering it alone can result in a fine powder that is difficult to handle. Therefore, in order to obtain the first polymer as a powder of an appropriate particle size that is easy to handle, it is desirable to produce the first polymer together with a second polymer having a large molecular weight and isolate the first polymer together with the second polymer. Furthermore, the presence of the second polymer improves the dispersibility of the first polymer in the polyamide resin, allowing the reaction between the polyamide resin and the first polymer to proceed efficiently, thereby further improving the moldability of the polyamide resin during melt processing.

[0024] From the viewpoint of improving granulation properties, the weight average molecular weight of the second polymer is 100,000 or more, preferably 150,000 or more, and more preferably 180,000 or more, in terms of polystyrene, as measured by GPC. There is no particular upper limit, but it is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less.

[0025] The monomer constituting the second polymer is not particularly limited, but preferably contains a methacrylic acid ester monomer and / or an aromatic vinyl monomer. From the viewpoint of improving moldability during melt processing and the tensile properties of the molded body, it is more preferable to contain an aromatic vinyl monomer. Furthermore, from the viewpoint of polymerization conversion rate and granulation property, it is more preferable to contain a methacrylic acid ester monomer.

[0026] The methacrylic acid ester monomer is not particularly limited, and examples thereof include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate; hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate, etc. Among these, alkyl methacrylate monomers are preferred, alkyl methacrylate monomers in which the alkyl group has 1 to 4 carbon atoms are more preferred, and methyl methacrylate is particularly preferred.

[0027] The aromatic vinyl monomer is not particularly limited, but examples thereof include styrene, α-methylstyrene, p-methylstyrene, etc. Among these, styrene is preferred.

[0028] The total content of the methacrylic acid ester monomer and the aromatic vinyl monomer is preferably 80% by weight or more and 100% by weight or less, more preferably 82% by weight or more and 99% by weight or less, and even more preferably 84% by weight or more and 98% by weight or less, of 100% by weight of the second polymer.

[0029] From the viewpoint of improving granulation properties, the second polymer preferably contains an acrylic acid ester monomer in addition to a methacrylic acid ester monomer and / or an aromatic vinyl monomer.

[0030] The acrylic acid ester monomer is not particularly limited, but examples thereof include alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, etc. Among these, alkyl acrylate monomers are preferred, alkyl acrylate monomers in which the alkyl group has 1 to 4 carbon atoms are more preferred, and butyl acrylate is particularly preferred.

[0031] From the viewpoint of improving granulation properties, the content of the acrylic acid ester monomer is preferably 0% by weight or more and 20% by weight or less, more preferably 1% by weight or more and 18% by weight or less, and even more preferably 2% by weight or more and 16% by weight or less, relative to 100% by weight of the second polymer.

[0032] The second polymer is preferably a non-rubber polymer, which allows the reaction between the carboxyl groups of the first polymer and the terminal amino groups of the polyamide resin to proceed more efficiently, making it easier to achieve improved moldability during melt processing and improved tensile properties of the molded article.

[0033] A preferred embodiment of the additive for polyamide resins may contain the first polymer and the second polymer, and the relationship between the two polymers is not particularly limited. However, from the viewpoint of improving granulation properties, it is preferred that the first polymer constitutes particles and at least a portion of the second polymer is located on the outside of the particles. At least a portion of the second polymer may coat the outer surface of the particles. Alternatively, a portion of the second polymer may be located on the outside of the particles, and the remainder may be impregnated into the interior of the particles. Furthermore, it is preferable that the first polymer and the second polymer are not chemically bonded to each other. In this case, it is considered that by kneading the additive with the polyamide resin, the first polymer and the second polymer exist separately from each other in the polyamide resin matrix.

[0034] The additive for polyamide resins according to the present embodiment is blended with a polyamide resin and used to improve the moldability of the polyamide resin during melt processing and the tensile properties of a polyamide resin-containing molded article. The amount of the additive blended with the polyamide resin can be appropriately determined, but the ratio of the additive to the total of the polyamide resin and the additive is preferably 0.1% by weight or more and 10% by weight or less. When the additive ratio is within this range, the additive can be effectively used to maintain the physical properties unique to the polyamide resin while improving the moldability during melt processing and the tensile properties of the molded article. The additive ratio is more preferably 0.2 to 8% by weight, and even more preferably 0.3 to 5% by weight. Furthermore, due to the significant effect of improving the tensile properties of the molded article, the additive ratio is particularly preferably 1.5% by weight or more.

[0035] (Method of manufacturing additives for polyamide resin) The method for producing the additive for polyamide resins can be a conventional polymerization method and is not particularly limited. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. can be used, with emulsion polymerization being preferred. When producing the first polymer, it is preferable to carry out polymerization in the presence of a chain transfer agent to control the molecular weight. Furthermore, when producing the first polymer and the second polymer continuously, first, a latex of the first polymer is produced by emulsion polymerization, and then the monomer components for the second polymer, a polymerization initiator, etc. are added to the latex to polymerize the monomer components.

[0036] The chain transfer agent that can be used when producing the first polymer is not particularly limited, and examples thereof include primary mercaptan chain transfer agents such as n-butyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, n-dodecyl mercaptan, and n-tetradecyl mercaptan; secondary mercaptan chain transfer agents such as sec-butyl mercaptan and sec-dodecyl mercaptan; tertiary mercaptan chain transfer agents such as t-dodecyl mercaptan; mercaptan compounds; thioglycolic acid esters such as 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris(thioglycolate), and pentaerythritol tetrakis(thioglycolate); thiophenol, tetraethylthiuram disulfide, pentanephenylethane, acrolein, methacrolein, allyl alcohol, carbon tetrachloride, ethylene bromide, styrene oligomers such as α-methylstyrene dimer, and terpinolene. These may be used alone or in combination of two or more. The amount of the chain transfer agent used may be appropriately determined depending on the desired weight average molecular weight of the first polymer.

[0037] The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may also be used. Among the above-mentioned emulsifiers, the anionic surfactant is not particularly limited, and examples thereof include the following compounds: fatty acid soaps such as potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium oleate diethanolamine salt, sodium oleate, potassium palmitate, potassium stearate, sodium stearate, mixed fatty acid soda soap, semi-hardened beef tallow fatty acid soda soap, and castor oil potassium soap; alkoxylated surfactants such as sodium dodecyl sulfate, higher alcohol sodium sulfate, triethanolamine dodecyl sulfate, ammonium dodecyl sulfate, sodium polyoxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and sodium 2-ethylhexyl sulfate; alkyl sulfate salts; sodium alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate; sodium dialkylsulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkylnaphthalenesulfonates; sodium alkyldiphenyletherdisulfonates; potassium alkylphosphate salts; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalenesulfonic acid formalin condensates; polycarboxylic acid type polymeric anions; sodium acyl (beef tallow) methyl taurate; sodium acyl (coconut) methyl taurate; sodium cocoyl isethionate; sodium α-sulfofatty acid ester salts; sodium amidoethersulfonate; oleyl sarcosine; sodium lauroyl sarcosine; rosin acid soap, etc.

[0038] Furthermore, among the above-mentioned emulsifiers, the nonionic surfactant is not particularly limited, and examples thereof include the following compounds: polyoxyethylene alkyl allyl ethers or polyoxyethylene alkyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether; polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate; and oxyethylene / oxypropylene block copolymers.

[0039] Furthermore, among the above emulsifiers, the cationic surfactant is not particularly limited, and examples thereof include the following compounds: alkylamine salts such as coconut amine acetate, stearyl amine acetate, octadecyl amine acetate, and tetradecyl amine acetate; and quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, alkyl benzyl dimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and behenyl trimethyl ammonium chloride.

[0040] Furthermore, among the above emulsifiers, the amphoteric surfactant is not particularly limited, but examples thereof include the following compounds: alkyl betaines such as lauryl betaine, stearyl betaine, and dimethyl lauryl betaine; sodium lauryl diaminoethyl glycine; amido betaine; imidazoline; lauryl carboxymethyl hydroxyethyl imidazolinium betaine; and the like.

[0041] These emulsifiers (dispersants) may be used alone or in combination of two or more.

[0042] When emulsion polymerization is employed, known polymerization initiators, such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used as thermal decomposition initiators.

[0043] Alternatively, a redox initiator can be used which is a combination of a peroxide such as an organic peroxide such as t-butyl peroxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, or t-hexyl peroxide; or an inorganic peroxide such as hydrogen peroxide, potassium persulfate, or ammonium persulfate, optionally with a reducing agent such as sodium formaldehyde sulfoxylate or glucose, optionally with a transition metal salt such as iron (II) sulfate, optionally with a chelating agent such as disodium ethylenediaminetetraacetate, and optionally with a phosphorus-containing compound such as sodium pyrophosphate.

[0044] When a redox initiator is used, polymerization can be carried out even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set over a wide range, which is preferable. Among these, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as the redox initiator. The amount of the initiator used, and when a redox initiator is used, the amount of the reducing agent, transition metal salt, chelating agent, etc. used can be within known ranges. Furthermore, when polymerizing a monomer having two or more radically polymerizable double bonds, known chain transfer agents can be used within known ranges. A surfactant can also be used, and this is also within known ranges.

[0045] The solvent used during emulsion polymerization may be any solvent that allows the emulsion polymerization to proceed stably, and for example, water can be suitably used.

[0046] The temperature during emulsion polymerization is not particularly limited as long as the emulsifier is dissolved uniformly in the solvent, but is, for example, 40 to 75°C, preferably 45 to 73°C, and more preferably 49 to 71°C.

[0047] When the additive for polyamide resins is produced by emulsion polymerization, the additive can be separated from the aqueous medium by, for example, coagulating the additive by mixing a latex of the additive with an acid such as hydrochloric acid or a divalent or higher metal salt such as calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, or calcium acetate, and then heat-treating, dehydrating, washing, and drying the additive according to a known method. The obtained additive is preferably washed with water and / or an organic solvent.

[0048] Alternatively, a water-soluble organic solvent such as an alcohol such as methanol, ethanol or propanol, or acetone may be added to the latex of the additive to precipitate the additive, and the additive may be separated from the solvent by centrifugation, filtration or the like, and then dried and isolated.Another method may be added to the latex of the additive to extract the additive in the latex into an organic solvent layer, and after separating the organic solvent layer, the additive may be mixed with water or the like to precipitate the additive.

[0049] Alternatively, the additive latex can be directly powdered by spray drying. The resulting powder is preferably washed with water and / or an organic solvent. Alternatively, calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, etc., preferably as an aqueous solution, can be added to the resulting powder, and the powder can be re-dried as needed, to achieve the same effect as the washing.

[0050] (Modifier for polyamide resin) The polyamide resin modifier of this embodiment contains the above-mentioned additive for polyamide resins and an impact modifier. The impact modifier is not particularly limited and may be a conventionally known one. Specific examples include one or more selected from the group consisting of a core-shell impact modifier, a polyolefin elastomer, a polyester elastomer, and a polyamide elastomer. Among these, a core-shell impact modifier or a polyolefin elastomer is preferred.

[0051] The core-shell impact strength improver is composed of polymer particles that are graft copolymers. The polymer particles are composed of a shell layer and one or more core layers. The shell layer refers to a polymer layer located on the surface side of the polymer particle and is also called a graft layer. The core layer refers to a polymer layer located more inward of the polymer particle than the shell layer and is composed of a rubbery polymer. The core layer may consist of only one layer, or may be composed of two or more layers each having a different monomer composition. The shell layer covers the surface of the core layer, but is not limited to covering the entire surface of the core layer, as long as it covers at least a portion of the surface of the core layer.

[0052] (core layer) The core layer is composed of a rubbery polymer, which preferably contains at least one selected from the group consisting of natural rubber, diene rubber, acrylate rubber, and polyorganosiloxane rubber, and more preferably contains at least one selected from the group consisting of diene rubber, acrylate rubber, and polyorganosiloxane rubber.

[0053] (Diene rubber) The diene rubber is an elastomer containing a constituent unit derived from a diene monomer as a constituent unit. The core layer more preferably contains a diene rubber, and particularly preferably is a diene rubber, because the glass transition temperature of the resulting elastomer can be lowered, the impact resistance of the resulting molded article of the polyamide resin composition is improved, and the raw material cost is low.

[0054] Examples of the diene monomer include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2-chloro-1,3-butadiene, etc. These diene monomers may be used alone or in combination of two or more.

[0055] The diene rubber may further contain, as a structural unit, a structural unit derived from a vinyl monomer other than the diene monomer that is copolymerizable with the diene monomer.

[0056] Examples of vinyl monomers other than diene monomers copolymerizable with diene monomers (hereinafter also referred to as vinyl monomer A) include: (a) aromatic vinyl monomers such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; (b) vinyl carboxylic acids such as acrylic acid and methacrylic acid; (c) alkyl (meth)acrylates such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate; (d) methacrylic acid, alkyl acrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; Examples of the vinyl monomer A include: (a) hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; (b) glycidyl group-containing vinyl monomers such as glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether; (c) unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; (d) vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; (e) vinyl acetate; and (f) alkenes such as ethylene, propylene, butylene, and isobutylene. The vinyl monomer A may be used alone or in combination of two or more.

[0057] There are no particular limitations on the content of constituent units derived from vinyl monomer A in the diene rubber. The diene rubber preferably contains 50 to 100% by weight of constituent units derived from diene monomers and 0 to 50% by weight of constituent units derived from vinyl monomer A, based on 100% by weight of constituent units.

[0058] The diene rubber may further contain, as a structural unit, a structural unit derived from a polyfunctional monomer such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, etc. In other words, these polyfunctional monomers may be used in the polymerization of the diene rubber.

[0059] Suitable examples of diene rubbers include butadiene rubber (polybutadiene rubber), styrene / butadiene copolymer rubber (poly(styrene / butadiene) rubber), poly(acrylonitrile / butadiene) rubber, butadiene / acrylic acid ester copolymer, etc. Butadiene rubber is an elastomer containing 50 to 100% by weight of structural units derived from 1,3-butadiene out of 100% by weight of structural units.

[0060] The diene rubber is preferably a butadiene rubber containing 50 to 100% by weight of structural units derived from 1,3-butadiene and 0 to 50% by weight of structural units derived from vinyl monomer A, and more preferably a 1,3-butadiene homopolymer containing 100% by weight of structural units derived from 1,3-butadiene.

[0061] It is more preferable that the core layer contains butadiene rubber, and it is particularly preferable that it is butadiene rubber, because this can lower the glass transition temperature of the resulting elastic body, has a high effect of improving the impact resistance of the molded article of the resulting polyamide resin composition, and has low raw material costs.

[0062] (Acrylate rubber) Acrylate rubber is an elastic material containing, as a structural unit, a structural unit derived from a (meth)acrylate monomer.

[0063] Examples of the (meth)acrylate monomer include: (a) (meth)acrylic acid alkyl esters having an alkyl group having 1 to 22 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (b) aromatic ring-containing (meth)acrylic acid esters, such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; (c) (meth)acrylic acid hydroxyalkyl esters, such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; (d) glycidyl group-containing (meth)acrylic acid esters, such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; and (e) (meth)acrylic acid alkoxyalkyl esters. These (meth)acrylate monomers may be used alone or in combination of two or more.

[0064] The acrylate rubber may further contain, as a structural unit, a structural unit derived from a vinyl monomer other than the (meth)acrylate monomer that is copolymerizable with the (meth)acrylate monomer. Examples of the vinyl monomer other than the (meth)acrylate monomer that is copolymerizable with the (meth)acrylate monomer include (a) the diene monomers described above, and (b) monomers of the vinyl monomer A other than the (meth)acrylate monomer.

[0065] The acrylic rubber has a crosslinked structure. To introduce the crosslinked structure, for example, a crosslinking agent and / or a graft crosslinking agent can be used when synthesizing the core layer polymer by polymerizing the monomer components. Examples of crosslinking agents and graft crosslinking agents include: (a) allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; (b) polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; and (c) polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. These crosslinking agents and graft crosslinking agents may be used alone or in combination of two or more.

[0066] Suitable examples of acrylate rubbers include polybutyl acrylate rubber and butyl acrylate / 2-ethylhexyl acrylate copolymer rubber. Polybutyl acrylate rubber is an elastomer containing 50 to 100% by weight of structural units derived from butyl acrylate out of 100% by weight of structural units.

[0067] Suitable examples of the polyorganosiloxane rubber include silicone rubber and silicone / acrylate rubber.

[0068] Examples of silicone rubbers include polymethylsilicone rubber and polymethylphenylsilicone rubber, etc. Examples of silicone / acrylate rubbers include polyorganosiloxane / butyl acrylate copolymers, etc.

[0069] In one embodiment, the core layer preferably includes one or more materials selected from the group consisting of butadiene rubber, styrene / butadiene copolymer rubber, acrylate rubber, and silicone rubber.

[0070] (shell layer) The shell layer is preferably formed from a polymer containing a structural unit derived from a vinyl monomer, such as an aromatic vinyl compound, a vinyl cyanide compound, an unsaturated carboxylic acid ester, an acrylamide monomer, or a maleimide monomer.

[0071] Suitable examples of the aromatic vinyl compound include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butylstyrene, α-methylvinyltoluene, dimethylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, and dibromostyrene.

[0072] Suitable examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, and ethacrylonitrile.

[0073] Suitable examples of the unsaturated carboxylic acid ester include: (a) alkyl acrylates having an alkyl group having 1 to 22 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, and behenyl acrylate; (b) alkyl methacrylates having an alkyl group having 1 to 22 carbon atoms, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, and behenyl methacrylate; and (c) alkoxyalkyl (meth)acrylates having an alkyl group having 1 to 22 carbon atoms and an alkoxyl group, such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate.

[0074] Suitable examples of the acrylamide monomer include acrylamide, methacrylamide, and N-methylacrylamide.

[0075] Suitable examples of the maleimide monomer include N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide.

[0076] The polymer constituting the shell layer preferably contains, as a constituent monomer, one or more selected from acrylic acid alkyl esters and methacrylic acid alkyl esters, which may be used alone or in combination of two or more.

[0077] Furthermore, the polymer constituting the shell layer preferably further contains, as a constituent monomer, at least one reactive vinyl monomer selected from the group consisting of carboxyl group-containing vinyl monomers, hydroxyl group-containing vinyl monomers, and glycidyl group-containing vinyl monomers. By including the reactive vinyl monomer as a constituent monomer in the shell layer, the core-shell impact modifier can be made reactive with the polyamide resin, thereby improving the dispersibility of the core-shell impact modifier in the polyamide resin and enhancing the impact strength improvement effect. At the same time, the dispersibility of the additive in the polyamide resin can also be improved. Among the reactive vinyl monomers, carboxyl group-containing vinyl monomers are preferred because of their particularly good reactivity with polyamide resins. The reactive vinyl monomers may be used alone or in combination of two or more.

[0078] Suitable examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, vinyloxyacetic acid, allyloxyacetic acid, 2-(meth)acryloylpropanoic acid, 3-(meth)acryloylbutanoic acid, 4-vinylbenzoic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, etc. Among these, acrylic acid and / or methacrylic acid are preferred, and methacrylic acid is more preferred.

[0079] Suitable examples of the hydroxyl group-containing vinyl monomer include (meth)acrylic acid hydroxyalkyl esters having an alkyl group with 1 to 22 carbon atoms and a hydroxyl group, such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0080] Suitable examples of the glycidyl group-containing vinyl monomer include glycidyl (meth)acrylate.

[0081] The amount of the reactive vinyl monomer used can be appropriately determined depending on the desired effect and is not particularly limited. However, when the reactive vinyl monomer is a carboxyl group-containing vinyl monomer, the proportion of the carboxyl group-containing vinyl monomer in the entire polymer particles of the core-shell impact strength modifier is preferably 0.05 to 1.4 wt%. When the proportion is within this range, the effect of adding the core-shell impact strength modifier to improve the impact strength of the polyamide resin can be enhanced. The lower limit of this proportion is preferably 0.1 wt%, more preferably 0.2 wt%. The upper limit of this proportion is preferably 1.2 wt%, more preferably 1.0 wt%, even more preferably 0.9 wt%, even more preferably 0.7 wt%, particularly preferably 0.6 wt%, and most preferably 0.5 wt%.

[0082] The weight proportion of the shell layer in the entire polymer particles that are the core-shell type impact strength improver is preferably 1 to 50% by weight, more preferably 5 to 40% by weight, and even more preferably 10 to 30% by weight, from the viewpoint of compatibility between the core-shell type impact strength improver and the polyamide resin, and from the viewpoint of the impact strength improving effect.

[0083] (Particle size of core-shell type impact strength modifier) The particle size of the polymer particles that are core-shell impact strength improvers can be set as appropriate, but the volume average particle size of the polymer particles is typically 100 nm or more. Since larger particle sizes tend to improve impact strength, particularly at low temperatures, the volume average particle size is preferably 130 nm or more, more preferably 150 nm or more, more preferably 160 nm or more, and even more preferably 170 nm or more. On the other hand, since larger particle sizes of the polymer particles tend to increase the time required for the polymerization reaction and reduce productivity, the volume average particle size is preferably 400 nm or less, more preferably 350 nm or less, even more preferably 300 nm or less, and even more preferably 250 nm or less. The volume average particle size of the polymer particles is a value measured using a particle size measuring device in the state of the polymer particles in a latex state, as shown in the Examples section. The volume average particle size of the polymer particles can also be calculated from transmission electron microscope (TEM) images of the polyamide resin composition. The particle size of the polymer particles can be controlled by the types and amounts of the polymerization initiator, chain transfer agent, oxidation-reduction agent, emulsifier, etc., the polymerization temperature, the polymerization time, etc.

[0084] (Method of manufacturing polymer particles that are core-shell type impact strength improvers) The polymer particles that are the core-shell type impact strength improver can be produced by a conventional method and is not particularly limited.For example, any of bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be adopted, but emulsion polymerization, i.e., emulsion graft polymerization, is preferred.In emulsion graft polymerization, specifically, first, a latex of particles that correspond to the core layer is produced by emulsion polymerization, and then monomer components and polymerization initiators for the shell layer are added to the latex to polymerize the monomer components.

[0085] (Polyolefin elastomer) Examples of the polyolefin elastomer include polyolefin elastomers and hydrogenated styrene thermoplastic elastomers. Specific examples include ethylene / propylene copolymers, ethylene / butene-1 copolymers, ethylene / hexene-1 copolymers, ethylene / propylene / dicyclopentadiene copolymers, ethylene / propylene / 5-ethylidene-2-norbornene copolymers, unhydrogenated or hydrogenated styrene / isoprene / styrene triblock copolymers, unhydrogenated or hydrogenated styrene / butadiene / styrene triblock copolymers, ethylene / methacrylic acid copolymers, or copolymers in which part or all of the carboxylic acid moieties in these copolymers have been converted into salts with sodium, lithium, potassium, zinc, or calcium; ethylene / methyl acrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / methyl methacrylate copolymers, ethylene / ethyl methacrylate copolymers, ethylene / ethyl acrylate-g-maleic anhydride copolymers ("g" represents graft, the same applies below), ethylene / methyl methacrylate-g-maleic anhydride copolymers, ethylene / ethyl acrylate-g-maleimide copolymers, ethylene / ethyl acrylate-g-N-phenylmaleimide copolymers, or partially saponified copolymers of these copolymers;Ethylene / glycidyl methacrylate copolymer, ethylene / vinyl acetate / glycidyl methacrylate copolymer, ethylene / methyl methacrylate / glycidyl methacrylate copolymer, ethylene / glycidyl acrylate copolymer, ethylene / vinyl acetate / glycidyl acrylate copolymer, ethylene / glycidyl ether copolymer, ethylene / propylene-g-maleic anhydride copolymer, ethylene / butene-1-g-maleic anhydride copolymer, ethylene / propylene / 1,4-hexadiene-g-maleic anhydride copolymer, ethylene / propylene / dicyclopentadiene-g-maleic anhydride copolymer, ethylene / propylene / 2,5-norbornadiene-g-maleic anhydride copolymer Examples of the copolymer include styrene / butadiene / styrene-g-maleic anhydride copolymer, ethylene / propylene-g-N-phenylmaleimide copolymer, ethylene / butene-1-g-N-phenylmaleimide copolymer, hydrogenated styrene / butadiene / styrene-g-maleic anhydride copolymer, hydrogenated styrene / isoprene / styrene-g-maleic anhydride copolymer, ethylene / propylene-g-glycidyl methacrylate copolymer, ethylene / butene-1-g-glycidyl methacrylate copolymer, ethylene / propylene / 1,4-hexadiene-g-glycidyl methacrylate copolymer, ethylene / propylene / dicyclopentadiene-g-glycidyl methacrylate copolymer, and hydrogenated styrene / butadiene / styrene-g-glycidyl methacrylate copolymer. Examples of industrially usable elastomers include TAFMER MH7020, MH7010, and MA8510 manufactured by Mitsui Chemicals, Inc., HIMILAN 1706 manufactured by Mitsui DuPont, SEBS TUFTEC M1943 manufactured by Asahi Kasei Corporation, and PA-bond 959, PA-bond 969, and PA-bond 979 manufactured by Polymer Asia Co., Ltd.;

[0086] The polyamide resin modifier of this embodiment contains the additive of this embodiment and an impact modifier, and the proportion of the additive contained in the modifier can be appropriately determined by those skilled in the art. However, from the viewpoint of the balance between the effects achieved by the additive and the effects achieved by the impact modifier, the proportion of the amount of the additive relative to the total amount of the additive and the impact modifier is preferably 0.1% by weight or more and 25% by weight or less, more preferably 0.5% by weight or more and 15% by weight or less, and even more preferably 1% by weight or more and 10% by weight or less.

[0087] The polyamide resin modifier of this embodiment can be produced by mixing the additive of this embodiment with an impact modifier. When producing the modifier, the additive and the impact modifier may be mixed in powder form, but it is preferable to mix the additive and the impact modifier in latex form and then dry them to obtain a powder. In particular, when the impact modifier is a core-shell impact modifier, the method of mixing with latex can dramatically improve the melt tension of the polyamide resin composition in addition to the impact strength improvement effect, which is effective for improving parison retention during blow molding. This is thought to be because the additive can be more compatible with the shell portion of the core-shell impact modifier during latex blending, and as a result, when the modifier is kneaded with the polyamide resin, the additive can also be uniformly dispersed in the polyamide resin along with the dispersion of the core-shell impact modifier.

[0088] (Amount of modifier blended) The polyamide resin modifier of this embodiment is blended with a polyamide resin to improve its melt-processing moldability, the tensile properties of molded articles, and the impact strength of the polyamide resin. The amount of modifier blended with the polyamide resin can be appropriately determined, but the proportion of the modifier relative to the total of the polyamide resin and the modifier is preferably 1% by weight or more and 40% by weight or less. When the modifier proportion is within this range, it is possible to appropriately improve the melt-processing moldability, the tensile properties of molded articles, and the impact strength of the polyamide resin while maintaining the physical properties unique to the polyamide resin. The proportion is more preferably 3 to 30% by weight, and even more preferably 5 to 25% by weight.

[0089] (Polyamide resin) The polyamide resin in this embodiment is not limited as long as it is a polymer having an acid amide bond (-CONH-). Examples include polymers obtained by polycondensation of diamines and dibasic acids, polymers obtained by polycondensation of diamine derivatives such as diformyl with dibasic acids, polymers obtained by polycondensation of dibasic acid derivatives such as dimethyl ester with diamines, polymers obtained by reaction of dinitriles or diamides with formaldehyde, polymers obtained by polyaddition of diisocyanates with dibasic acids, polymers obtained by self-condensation of amino acids or their derivatives, and polymers obtained by ring-opening polymerization of lactams. The polyamide resin may also contain a polyether block. One type of polyamide resin may be used alone, or two or more types may be mixed together.

[0090] Specific examples of polyamide resins include aliphatic polyamides such as nylon 4, nylon 6, nylon 6,6, nylon 7, nylon 9, nylon 11, nylon 12, nylon 46, nylon 56, nylon 410, nylon 412, nylon 610, and nylon 612, semi-aromatic polyamides such as nylon 6T, nylon 6I, nylon 9T, nylon 10T, nylon M5T, and nylon MXD6, and copolymer polyamides such as nylon 6 / 66, nylon 6 / 12, nylon 6 / 66 / 12, nylon 6 / 6T, nylon 66 / 6T, nylon 6 / 6I, nylon 6T / 6I, nylon 6T / 12, and nylon 66 / 6T / 6I. Of these, nylon 6, nylon 6,6, nylon 11, and nylon 12 are preferred from the viewpoint of versatility.

[0091] (other resins) The polyamide resin composition of this embodiment may or may not contain a thermoplastic resin other than the polyamide resin. When a thermoplastic resin other than the polyamide resin is contained, the thermoplastic resin is not particularly limited, but examples thereof include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, polyacetal, polycarbonate, modified polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, and cyclic polyolefin. The amount of the other thermoplastic resin is not particularly limited, but is, for example, 0 to 100 parts by weight, preferably 0 to 50 parts by weight, more preferably 0 to 30 parts by weight, and even more preferably 0 to 10 parts by weight, per 100 parts by weight of the polyamide resin.

[0092] (Other additives) The polyamide resin composition of the present embodiment may contain, as appropriate, additives that can be blended into general thermoplastic resin compositions, including, but not limited to, flame retardants, flame retardant auxiliaries, anti-dripping agents, reinforcing materials, fillers, antioxidants, pigments, dyes, conductivity-imparting agents, hydrolysis inhibitors, thickeners, plasticizers, lubricants, UV absorbers, antistatic agents, flow improvers, release agents, compatibilizers, and heat stabilizers.

[0093] From the viewpoint of improving impact strength, the polyamide resin composition of this embodiment preferably further contains a reinforcing material. Examples of reinforcing materials include glass fiber, carbon fiber, boron fiber, asbestos fiber, polyvinyl alcohol fiber, polyester fiber, acrylic fiber, wholly aromatic polyamide fiber, polybenzoxazole fiber, polytetrafluoroethylene fiber, kenaf fiber, bamboo fiber, hemp fiber, bagasse fiber, high-strength polyethylene fiber, alumina fiber, silicon carbide fiber, potassium titanate fiber, brass fiber, stainless steel fiber, steel fiber, ceramic fiber, and basalt fiber. Among these, glass fiber, carbon fiber, and metal fiber are preferred, and glass fiber is more preferred, due to their high impact strength improving effect. The reinforcing materials may be used alone or in combination of two or more.

[0094] The amount of the reinforcing material to be blended can be set as appropriate, but the proportion of the reinforcing material relative to the total of the polyamide resin and the reinforcing material (100% by weight) is preferably 10 to 60% by weight, more preferably 15 to 50% by weight, and even more preferably 20 to 40% by weight.

[0095] (Method of producing the composition) The method for producing the polyamide resin composition of this embodiment is not particularly limited, and a general method for producing a thermoplastic resin composition can be applied. For example, the raw materials can be mixed using a Henschel mixer, a tumbler mixer, or the like, and then melt-kneaded to obtain the polyamide resin composition. For the melt-kneading, a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll can be used. By such melt-kneading, pellets made of the polyamide resin composition can be produced.

[0096] The polyamide resin composition of the present embodiment can be molded into a predetermined shape to form a molded article. The molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, blow molding, foam molding, calendar molding, inflation molding, rotational molding, and press molding.

[0097] (Application) The polyamide resin composition of the present embodiment and molded articles thereof are suitable for use in automotive applications such as cylinder head covers, engine covers, intake manifolds, radiator tanks, oil pans, accelerator pedals, canisters, fuel tubes, air brake tubes, exhaust gas tubes, hydrogen injectors, ducts, industrial fasteners, and door mirror stays; electrical and electronic applications such as coil bobbins, connectors, gears, sockets, switches, electric blanket coated wires, optical fiber cable coating materials, power tools, and electric wire ties; hydraulic and pneumatic connectors and tubes, bearings, covers and housings, and shafts. Examples of applications include, but are not limited to, mechanical applications such as receivers, pressure-resistant hoses, and cable ties; building material applications such as curtain rail parts, aluminum sash corners, door rollers, handrails, curtain rollers, and door handles; sports and leisure applications such as sports shoe soles, ski and snowboard equipment, reels, and diving snorkels; packaging and container applications such as shrink wrapping film, food packaging film, alcoholic beverage bottles, and pesticide bottles; everyday applications such as toothbrushes, chair legs and armrests, combs, knives and forks; and medical applications such as medical catheters and pipes, medical packs, and sutures. [Example]

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0099] (Weight average molecular weight) The weight-average molecular weight was determined by dissolving a sample in tetrahydrofuran (THF), filtering the soluble fraction through a 0.2 μm filter, and then measuring it with a high-speed GPC system (HLC-8220, manufactured by Tosoh Corporation) (sample solution: 20 mg sample / 10 mL THF, columns: one TSKguardcolumn SuperHZ-H and two TSKgel SuperHZM-H, both manufactured by Tosoh Corporation, column temperature: 40°C, detector: differential refractometer, flow rate: 0.35 mL / min, injection volume: 10 μL, calibration curve: standard polystyrene).

[0100] (Volume average particle size of polymer particles) The volume average particle size of the polymer particles was measured in the state of polymer particle latex using a Nanotrac Wave manufactured by Nikkiso Co., Ltd. as the measuring device.

[0101] (polymerization conversion rate) A portion of the obtained latex was sampled and weighed, and dried in a hot air oven at 120°C for 1 hour. The weight after drying was then weighed as the solid content. The ratio of the weighed amounts before and after drying was calculated as the solid content in the latex. Finally, the polymerization conversion rate was calculated using the solid content ratio according to the following formula. Formula: Polymerization conversion rate = (total weight of raw materials charged × solid component ratio - total weight of raw materials other than monomers) / weight of charged monomer × 100 (%)

[0102] (Example of additive manufacturing) As a representative method for producing additives, the production procedure for the additives used in Examples 1 and 2 is shown below. The additives used in the examples and comparative examples other than Examples 1 and 2 were produced in accordance with the following description for Examples 1 and 2, except that the type and amount of the monomer used and the amount of the chain transfer agent were changed according to the description in the table.

[0103] <Manufacturing additive latex> A glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier adding device was charged with 100 parts by weight of deionized water, 0.147 parts by weight of sodium hydroxide, and 1.353 parts by weight of polyoxyethylene lauryl ether phosphate, and the temperature was raised to 70°C while stirring in a nitrogen stream. 0.0025 parts by weight of disodium ethylenediaminetetraacetate, 0.0015 parts by weight of ferrous sulfate heptahydrate, 0.3 parts by weight of sodium formaldehyde sulfoxylate, and 0.01 parts by weight of t-butyl hydroperoxide were added to the mixture and stirred. To this mixture, 11.05 parts by weight of methacrylic acid (hereinafter referred to as MAA), 38.95 parts by weight of styrene (hereinafter referred to as ST), 0.9 parts by weight of t-dodecyl mercaptan (chain transfer agent), 0.9 parts by weight of n-dodecyl mercaptan (chain transfer agent), and 0.451 parts by weight of polyoxyethylene lauryl ether phosphate were added over 150 minutes. During the addition, aqueous sodium hydroxide solution was added as needed to maintain the pH at 6.5 to 7.0, and t-butyl hydroperoxide was added as needed to promote polymerization. After the addition of the mixture was completed, the mixture was stirred for 30 minutes while cooling the temperature from 70°C to 50°C. T-butyl hydroperoxide was added as needed during stirring to promote polymerization. As a result, a first polymer was formed with a polymerization conversion rate of 97%. Then, a mixture of 43.28 parts by weight of ST, 6.72 parts by weight of butyl acrylate (hereinafter referred to as BA), 0.451 parts by weight of polyoxyethylene lauryl ether phosphate, and 0.08 parts by weight of t-butyl hydroperoxide was added over 150 minutes. During the addition, aqueous sodium hydroxide solution was added as needed to maintain the pH at 6.5 to 7.0. After the addition was completed, 0.01 parts by weight of t-butyl hydroperoxide was added three times every 10 minutes, followed by stirring for 30 minutes to form a second polymer with a polymerization conversion rate of 98%. This resulted in an additive latex containing the first polymer and the second polymer. <Obtaining white resin powder as an additive> 650 parts by weight of deionized water and 3.5 parts by weight of a 25% by weight calcium chloride aqueous solution were heated to 70°C while stirring, and the additive latex was added thereto to obtain a slurry containing coagulated latex particles. The coagulated latex particle slurry was then heated to 95°C, dehydrated, and dried to obtain a particulate additive containing the first polymer and the second polymer as a white resin powder.

[0104] (Examples 1 to 15 and Comparative Examples 1 to 3) Production of Polyamide Resin Compositions Pellets and test pieces composed of a composition containing a polyamide resin and the white resin powder of the additive were prepared according to the following description, and the MFR, tensile properties, Izod impact strength, and HDT were measured. However, in Comparative Example 1, the evaluation was carried out without using the white resin powder of the additive. The MFR or melt tension was used as an index of moldability during melt processing. A smaller MFR value indicates lower fluidity during melt processing and better moldability during melt processing. Furthermore, a larger melt tension value indicates better moldability during melt processing.

[0105] (Pellet and test piece preparation conditions) (a) Polyamide 6 resin (Durethan B29 manufactured by Lanxess) 99.0 parts by weight or 98.0 parts by weight (b) 1 part by weight or 2 parts by weight of the white resin powder of the additive (c) 0.1 parts by weight of hindered phenol antioxidant (Irganox 1076 manufactured by BASF) (d) Phosphorus-based processing stabilizer (Irgafos 168 manufactured by BASF) 0.2 parts by weight

[0106] The mixture of (a) to (d) was kneaded and extruded in a twin-screw extruder (TEX44SS manufactured by The Japan Steel Works, Ltd.) heated to a barrel temperature of 230 to 260° C. at a screw rotation speed of 100 rpm to obtain pellets. The pellets were dried in a dryer at 80°C for 12 hours to sufficiently reduce the moisture content, and then test specimens were produced using an injection molding machine (FAS100B manufactured by Fanuc Corporation) at a molding temperature of 270-290°C and a mold temperature of 80°C.

[0107] (MFR) The pellets prepared under the above conditions were dried in a hot air dryer at 120°C for 12 hours, and then the MFR value was measured in accordance with JIS K7210 Method A at a measurement temperature of 280°C and a load of 5 kg.

[0108] (melt tension) The melt tension was determined by measuring the stress when the pellets prepared under the above conditions were melted and stretched at a constant acceleration, and was measured under the following conditions: The melt tension was measured for Examples 7-8 and 16 and Comparative Examples 1 and 4-5. [Measurement conditions] Model used: Capillary rheometer (Gottfert, RG25) Capillary die: diameter 2 mm, length 20 cm Winding speed: 17mm / s Acceleration: (Table 1) 6mm / s 2 , (Table 2) 12mm / s 2 Measurement temperature: (Table 1) 228℃, (Table 2) 238℃

[0109] (Tensile properties) The 3.2 mm thick ASTM D638-1 type test pieces prepared by the above-mentioned method were measured for tensile properties (tensile modulus, tensile yield stress, tensile breaking stress, and tensile breaking strain) in an absolute dry state at 23°C at a test speed of 50 mm / min according to the method in accordance with the ASTM D638 standard.

[0110] (Izod impact strength) The Izod impact strength of the v-notched test specimens, 63.5 mm long, 12.7 mm wide, and 3.2 mm thick, prepared by the method described above, was measured in an absolute dry state at -30°C and 23°C using a method in accordance with ASTM D256 standard.

[0111] (HDT) The test piece, 127 mm long, 12.7 mm wide, and 6.4 mm thick, was annealed at 100°C for 1 hour and then subjected to a test of 18.6 kgf / cm using a method in accordance with ASTM D648. 2 The HDT was measured at a load of 1000 kJ / s. The results of the above measurements are shown in Table 1.

[0112] [Table 1]

[0113] From Table 1, it can be seen that Examples 1 to 15 have significantly smaller MFR values ​​than Comparative Examples 1 to 3, i.e., good moldability during melt processing, and that the tensile properties of the molded bodies are also good compared to Comparative Examples 1 and 2. Among the Examples, Examples 7 to 15 are particularly good. Furthermore, Examples 7 and 8 have larger melt tension values ​​than Comparative Example 1, which also indicates good moldability during melt processing. Note that Comparative Example 1 does not contain any additives, and the additives used in Comparative Examples 2 and 3 do not contain methacrylic acid, a carboxyl group-containing vinyl monomer, but instead contain glycidyl methacrylate, an epoxy group-containing vinyl monomer.

[0114] (Production of core-shell impact strength improvers) <Production of polybutadiene rubber latex (core layer)> A pressure-resistant polymerization reactor was charged with 170 parts by weight of deionized water, 0.002 parts by weight of disodium ethylenediaminetetraacetate, 0.0012 parts by weight of ferrous sulfate heptahydrate, and 0.13 parts by weight of sodium dodecylbenzenesulfonate. The mixture was thoroughly degassed with stirring to remove oxygen, after which 100 parts by weight of butadiene (hereinafter referred to as BD) was added to the system and the temperature was raised to 45°C. 0.05 parts by weight of sodium formaldehyde sulfoxylate and 0.03 parts by weight of paramenthane hydroperoxide were added to initiate polymerization. At 6, 10, 14, and 17 hours after the start of polymerization, 0.014 parts by weight of paramenthane hydroperoxide were added. After 20 hours of polymerization, the remaining monomer was removed under reduced pressure to volatilize and terminate the polymerization, yielding a polybutadiene rubber latex composed primarily of polybutadiene rubber and having a volume-average particle size of 180 nm.

[0115] <Production of polymer particle latex> A glass reactor equipped with a thermometer, stirrer, reflux condenser, nitrogen inlet, and monomer and emulsifier addition apparatus was charged with 30 parts by weight of deionized water and the polybutadiene rubber latex described above to a solids content of 78 parts by weight. The mixture was heated to 60°C while stirring in a nitrogen stream. Next, 0.00032 parts by weight of disodium ethylenediaminetetraacetate, 0.00008 parts by weight of ferrous sulfate, and 0.04 parts by weight of sodium formaldehyde sulfoxylate were charged. A mixture of 19.62 parts by weight of methyl methacrylate (hereinafter referred to as MMA), 2.18 parts by weight of BA, 0.2 parts by weight of MAA, and 0.024 parts by weight of t-butyl hydroperoxide was added over 68 minutes. Five minutes after the completion of the addition, 0.015 parts by weight of sodium formaldehyde sulfoxylate was added, and after another five minutes, 0.01 parts by weight of t-butyl hydroperoxide was added, and after another five minutes, 0.01 parts by weight of t-butyl hydroperoxide was added. This process was repeated twice, and the mixture was stirred for 50 minutes to obtain a polymer particle latex with a polymerization conversion rate of 100%.

[0116] (Production of modifiers containing additives and polymer particles) The polymer particle latex containing 3.0 parts by weight of the hindered phenol antioxidant IRGANOX-1076 [n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate] was blended with the additive latex used in Examples 7 and 8 in a 98:2 solids ratio (by weight) to obtain a blended latex. 760 parts by weight of deionized water and 3.5 parts by weight of a 25% calcium chloride aqueous solution were heated to 60°C with stirring, and the blended latex was added to obtain a slurry containing coagulated latex particles. The coagulated latex particle slurry was then heated to 90°C, dehydrated, and dried to obtain a modifier containing the additive and polymer particles (core-shell impact strength modifier) ​​as a white resin powder. Also, polymer particles (core-shell impact strength modifier) ​​alone were obtained as a white resin powder in the same manner except that the additive latex was not used.

[0117] (Example 16 and Comparative Examples 4 to 5) Production of Polyamide Resin Composition According to the formulations shown in Table 2, pellets and test pieces composed of a composition containing a polyamide resin and the white resin powder of the modifier were prepared according to the methods described above, and the MFR, melt tension, tensile properties, and Izod impact strength were measured according to the methods described above. However, in Comparative Example 4, evaluation was performed without using the white resin powder of the modifier, and in Comparative Example 5, evaluation was performed using a white resin powder containing only the polymer particles (core-shell impact strength modifier) ​​instead of the white resin powder of the modifier. The results obtained are shown in Table 2. As the polyamide resin, polyamide 6 resin (UBE 1030B manufactured by Ube Industries, Ltd.) was used.

[0118] [Table 2]

[0119] From Table 2, it can be seen that Example 16 has a smaller MFR value and a larger melt tension value than Comparative Examples 4 and 5, i.e., good moldability during melt processing, and also has better tensile properties and Izod impact strength than Comparative Example 5.

[0120] (Examples 17 to 21 and Comparative Examples 6 to 8) Production of Polyamide Resin Compositions Pellets and test pieces composed of a composition containing a glass fiber reinforced polyamide resin, the additive white resin powder, and optionally a polyolefin elastomer according to the formulations shown in Table 3 were prepared as described below, and the MFR, tensile properties, Izod impact strength, and HDT were measured according to the methods described above. However, in each comparative example, evaluation was performed without using the additive white resin powder. The results obtained are shown in Table 3.

[0121] (Pellet and test piece preparation conditions) (a) Glass fiber reinforced polyamide 6 resin (CM1016G-30 manufactured by Toray Industries, Inc., containing 30% by weight of glass fiber) Parts by weight shown in Table 3 (b) White resin powder of the additive used in Examples 7 and 8, parts by weight as shown in Table 3 (c) Maleic anhydride-modified polyolefin elastomer (MH7020 manufactured by Mitsui Chemicals, Inc.) Parts by weight shown in Table 3 (d) 0.21 parts by weight of hindered phenol antioxidant (Irganox 1076 manufactured by BASF) (e) Phosphorus-based processing stabilizer (Irgafos 168 manufactured by BASF) 0.09 parts by weight

[0122] Pellets were obtained from the mixture of (a) to (e) by the method described above, and then test pieces were prepared.

[0123] [Table 3]

[0124] From Table 3, it can be seen that Examples 17 to 19, in which the above-mentioned additives were blended into the glass fiber reinforced polyamide resin, had smaller MFR values ​​than Comparative Example 6, which did not contain the above-mentioned additives, i.e., had good moldability during melt processing, and also had better tensile properties and Izod impact strength than the comparative example. For the system in which a polyolefin elastomer is blended with a glass fiber reinforced polyamide resin, Example 20, which contains the additive, has a smaller MFR value and is better in both tensile properties and Izod impact strength than Comparative Example 7, which does not contain the additive. Example 21 also has a smaller MFR value and is better in both tensile properties and Izod impact strength than Comparative Example 8.

[0125] (Examples 22 to 27 and Comparative Examples 9 to 10) Production of Polyamide Resin Compositions Pellets and test pieces composed of compositions containing polyamide resin and the white resin powder of the additive according to the formulations shown in Table 4 were prepared as described below, and the MFR, tensile properties, Izod impact strength, and HDT were measured according to the methods described above. However, in each comparative example, evaluation was performed without using the white resin powder of the additive. The results obtained are shown in Table 4.

[0126] (Pellet and test piece preparation conditions) (a) Polyamide 66 resin (Leona 1300 manufactured by Asahi Kasei Corporation or Leona 1700 manufactured by Asahi Kasei Corporation) Parts by weight shown in Table 4 (b) White resin powder of the additive used in Examples 7 and 8, parts by weight as shown in Table 4 (c) 0.21 parts by weight of hindered phenol antioxidant (Irganox 1076 manufactured by BASF) (d) Phosphorus-based processing stabilizer (Irgafos 168 manufactured by BASF) 0.09 parts by weight

[0127] Pellets were obtained from the mixture of (a) to (d) by the method described above, and then test pieces were prepared.

[0128] [Table 4]

[0129] Table 4 shows that Examples 22 to 24, in which the additives were blended with nylon 6,6, had smaller MFR values ​​than Comparative Example 9, which did not contain the additives, i.e., had good moldability during melt processing, and also had better tensile properties than Comparative Example 9. Moreover, it is also clear that in Examples 25 to 27, compared with Comparative Example 10, the MFR values ​​are small and the tensile properties are good.

Claims

1. An additive for polyamide resins, comprising a first polymer and a second polymer, The first polymer contains, as a constituent monomer, (i) a carboxyl group-containing vinyl monomer, and (ii) a (meth)acrylic acid ester monomer and / or an aromatic vinyl monomer; is a copolymer comprising the first polymer has a weight average molecular weight of 2,000 to 25,000; the second polymer is a polymer containing, as a constituent monomer, a methacrylic acid ester monomer and / or an aromatic vinyl monomer, the second polymer has a weight average molecular weight of 100,000 or more, The additive for polyamide resins, wherein the first polymer and the second polymer are each a non-rubber polymer, the first polymer constitutes particles, and at least a portion of the second polymer is located outside the particles.

2. 2. The additive for polyamide resins according to claim 1, wherein the carboxyl group-containing vinyl monomer accounts for 15% by weight or more and 50% by weight or less of 100% by weight of the first polymer.

3. 3. The additive for polyamide resins according to claim 1 or 2, wherein the first polymer is a copolymer containing, as constituent monomers, (i) a carboxyl group-containing vinyl monomer and (ii) a (meth)acrylic acid ester monomer.

4. The additive for polyamide resins according to any one of claims 1 to 3, wherein the total of the methacrylic acid ester monomer and the aromatic vinyl monomer accounts for 80% by weight or more and 100% by weight or less of 100% by weight of the second polymer.

5. A modifier for polyamide resins, comprising the additive according to any one of claims 1 to 4 and an impact strength improver.

6. 6. The polyamide resin modifier according to claim 5, wherein the impact strength modifier is a core-shell type impact strength modifier.

7. 6. The polyamide resin modifier according to claim 5, wherein the impact strength improver is a polyolefin elastomer.

8. A polyamide resin and the additive for polyamide resins according to any one of claims 1 to 4, a polyamide resin composition in which the additive accounts for 0.1 to 10% by weight relative to 100% by weight of the total of the polyamide resin and the additive;

9. A polyamide resin modifier comprising: a polyamide resin; and the modifier for polyamide resin according to any one of claims 5 to 7, a polyamide resin composition in which the modifier accounts for 1 to 40% by weight relative to 100% by weight of the total of the polyamide resin and the modifier;

10. 10. The polyamide resin composition according to claim 8, further comprising a reinforcing material, wherein the proportion of the reinforcing material is 10 to 60% by weight relative to 100% by weight of the total of the polyamide resin and the reinforcing material.

11. A pellet comprising the polyamide resin composition according to any one of claims 8 to 10.

12. A molded article made of the polyamide resin composition according to any one of claims 8 to 10.

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