Modifier for polyamide resin and polyamide resin composition

Abstract

To provide a modifier for polyamide resin which enables improvement of impact strength of polyamide resin.SOLUTION: A modifier for polyamide resin is provided which is composed of polymer particles. Each of the polymer particles has core-shell structure of a shell layer and one or more core layers, and the polymer particle has a volume average particle diameter of 150 nm or more. At least the one core layer among the core layers is composed of polybutadiene or poly(butadiene-styrene). The shell layer is composed of a polymer of 50 wt.% or more of a methacrylate monomer and 0-50 wt.% of other monomer copolymerizable with the methacrylate monomer. The polymer constituting the shell layer includes a hydroxyl group-containing vinyl monomer as a constituent monomer.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Conventionally, as a technique for improving the impact resistance of a thermoplastic resin, a method of blending a graft copolymer containing a rubber component with the thermoplastic resin has been known.

[0003] However, when the thermoplastic resin is a polyamide resin, the polyamide resin and the rubber-containing graft copolymer generally have low compatibility, so that the rubber-containing graft copolymer does not disperse sufficiently in the polyamide resin, and the effect of improving the impact strength of the polyamide resin by blending the rubber-containing graft copolymer is not necessarily sufficient.

[0004] For example, Patent Documents 1 and 2 disclose that the impact strength of a polyamide resin can be improved by blending core-shell type polymer particles with the polyamide resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-004334 A [Patent Document 2] JP 2000-186204 A Summary of the Invention [Problem to be solved by the invention]

[0006] There is a demand for the development of a modifier that can further improve the impact strength of polyamide resins.

[0007] In view of the above-mentioned current situation, an object of the present invention is to provide a modifier for polyamide resins capable of improving the impact strength of polyamide resins, and a polyamide resin composition containing the modifier. [Means for solving the problem]

[0008] The present inventors have discovered that the impact strength of a polyamide resin can be significantly improved by using a specific monomer in the shell layer of core-shell type polymer particles to be blended with the polyamide resin, and have arrived at the present invention.

[0009] That is, the present invention relates to a polyamide resin modifier comprising polymer particles, the polymer particles having a core-shell structure comprising a shell layer and one or more core layers, the polymer particles having a volume average particle diameter of 150 nm or more, at least one layer of the core layers being composed of polybutadiene or poly(butadiene-styrene), the shell layer being composed of a polymer of 50% by weight or more of a methacrylic acid ester monomer and 0 to 50% by weight of another monomer copolymerizable with the methacrylic acid ester monomer, and the polymer constituting the shell layer contains a hydroxyl group-containing vinyl monomer as a constituent monomer. Preferably, the proportion of the hydroxyl group-containing vinyl monomer in the entire polymer particles is 0.1% by weight or more and 10% by weight or less. Preferably, the core layer exhibits a refractive index of 1.47 or greater. Preferably, the polyamide resin has a total content of 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units in the diamine units constituting the polyamide resin of not less than 0 mol % and less than 60 mol %. The present invention also relates to a polyamide resin composition comprising a polyamide resin and the modifier for polyamide resin, the proportion of the modifier being 1 to 40% by weight based on the total weight of the polyamide resin and the modifier. Preferably, the polyamide resin composition further contains 0.1 to 2.0 parts by weight of a carbodiimide compound based on 100 parts by weight of the polyamide resin composition. Preferably, the polyamide resin composition further contains 10 to 60 parts by weight of a reinforcing material based on 100 parts by weight of the polyamide resin composition. The present invention further relates to pellets or molded articles made of the polyamide resin composition. Effect of the Invention

[0010] According to the present invention, it is possible to provide a modifier for polyamide resins capable of improving the impact strength of polyamide resins, and a polyamide resin composition containing the modifier. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail.

[0012] (Modifier for polyamide resin) The polyamide resin modifier according to the present disclosure is composed of polymer particles which 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 on the inside of the polymer particle relative to the shell layer, and is composed of a rubber-like polymer. The core layer may be only one layer, or may be composed of two or more layers having different monomer compositions. The shell layer covers the surface of the core layer, but is not limited to covering the entire surface of the core layer, and may cover at least a part of the surface of the core layer.

[0013] (Core layer) The core layer of the polymer particles is composed of a rubber-like polymer, and the rubber-like polymer in at least one of the core layers is selected from polybutadiene or poly(butadiene-styrene). By using polybutadiene or poly(butadiene-styrene) in the core layer, the refractive index of the core layer is improved compared to when, for example, an acrylic rubber is used, and as a result, the color development of the polyamide resin composition is improved, and the decrease in the color development of the polyamide resin due to the blending of the polymer particles can be suppressed. In addition, the impact strength of the polyamide resin composition is also improved. Among them, polybutadiene is particularly preferred from the viewpoint of high impact strength improvement effect and raw material cost. The ratio of styrene in poly(butadiene-styrene) is not particularly limited, but is preferably 0.01 to 50% by weight.

[0014] The polybutadiene or poly(butadiene-styrene) may not contain vinyl monomers other than butadiene and styrene, or may contain such vinyl monomers. Examples of such vinyl monomers include aromatic vinyl monomers (excluding styrene) such as α-methylstyrene; (meth)acrylic acid and (meth)acrylic acid alkyl esters such as acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate; and unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile.

[0015] The polybutadiene or poly(butadiene-styrene) may be one in which a multifunctional monomer such as divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, or 1,3-butylene dimethacrylate is used during polymerization.

[0016] Furthermore, the polybutadiene or poly(butadiene-styrene) may be polymerized without using a chain transfer agent, or may be polymerized in the presence of a chain transfer agent. By using a chain transfer agent, the impact strength of the polyamide resin composition at low temperature is improved, and the incidence of brittle fracture in an impact test at low temperature tends to decrease and the incidence of ductile fracture tends to increase. Usable chain transfer agents are not particularly limited, and examples thereof include alkyl mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, t-decyl mercaptan, n-decyl mercaptan, and n-octyl mercaptan, and alkyl ester mercaptans such as 2-ethylhexyl thioglycolate.

[0017] When a chain transfer agent is used, the amount is not particularly limited, but is preferably 0.01 to 3% by weight based on the total amount of polybutadiene or poly(butadiene-styrene). When the amount of the chain transfer agent is within the above range, the effect of improving the impact strength of the polyamide resin by blending the polymer particles can be enhanced. The amount is more preferably 0.05 to 2% by weight, and even more preferably 0.1 to 1% by weight.

[0018] The core layer preferably has a refractive index of 1.47 or more. By using a core layer having such a refractive index, the color development of the polyamide resin composition is further improved, and the decrease in color development of the polyamide resin due to the incorporation of polymer particles can be further suppressed. The refractive index of the core layer is more preferably 1.48 or more, even more preferably 1.49 or more, even more preferably 1.50 or more, and particularly preferably 1.51 or more. The upper limit of the refractive index is not particularly limited, but may be, for example, 1.55 or less, and preferably 1.53 or less.

[0019] (Shell layer) The shell layer is composed of a polymer of 50% by weight or more of a methacrylic acid ester monomer and 0 to 50% by weight of another monomer copolymerizable with the methacrylic acid ester monomer. Since the shell layer is composed of a polymer in which the methacrylic acid ester monomer accounts for 50% by weight or more, the glass transition temperature of the shell layer is high, the polymer particles are less likely to become coarse particles, and the mechanical stability of the latex of the polymer particles is also good, making it suitable for industrial production.

[0020] The methacrylic acid ester monomer constituting the shell layer is not particularly limited, and examples thereof include methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, and behenyl methacrylate. Among these, methyl methacrylate is preferred. The hydroxyl group-containing vinyl monomer described below may be one corresponding to the methacrylic acid ester monomer. In addition, in order to avoid isobutylene gas generation during melt processing of the polyamide resin composition, it is preferable not to use t-butyl methacrylate.

[0021] The ratio of the methacrylic acid ester monomer to the entire monomer components of the polymer constituting the shell layer is 50 to 100% by weight. When the methacrylic acid ester monomer accounts for more than half of the shell layer of the polymer particle, the polymer particles are unlikely to become coarse in the powdering process for obtaining a powder of the polymer particles from the latex, so that the obtained polymer particles are easily uniformly dispersed in the polyamide resin, and the mechanical stability of the latex of the polymer particles is also good. The ratio is preferably 60 to 99% by weight, more preferably 70 to 97% by weight, and even more preferably 75 to 95% by weight. In addition, when the hydroxyl group-containing vinyl monomer described later corresponds to the methacrylic acid ester monomer, the ratio of the methacrylic acid ester monomer is calculated including the amount of the hydroxyl group-containing vinyl monomer.

[0022] The monomer component of the polymer constituting the shell layer of the polymer particle may contain, in addition to the methacrylic acid ester monomer, other monomers copolymerizable with the methacrylic acid ester monomer. Such monomers are not particularly limited, but acrylic acid alkyl esters are preferred. Examples of acrylic acid alkyl esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, and behenyl acrylate. Among them, butyl acrylate is preferred. The hydroxyl group-containing vinyl monomer described later may be one that corresponds to the other monomers copolymerizable with the methacrylic acid ester monomer.

[0023] The proportion of the other copolymerizable monomer in the total monomer components of the polymer constituting the shell layer is 0 to 50% by weight. The proportion is preferably 1 to 40% by weight, more preferably 3 to 30% by weight, and even more preferably 5 to 25% by weight. When a hydroxyl group-containing vinyl monomer described later corresponds to the other copolymerizable monomer, the proportion of the other copolymerizable monomer is calculated including the amount of the hydroxyl group-containing vinyl monomer.

[0024] The weight proportion of the shell layer in the entire polymer particle 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 polymer particle and the polyamide resin and the effect of improving impact strength.

[0025] The polymer constituting the shell layer contains a hydroxyl group-containing vinyl monomer as a constituent monomer. The hydroxyl group-containing vinyl monomer is preferably contained in at least the polymer constituting the shell layer, and in this case, the hydroxyl group-containing vinyl monomer may be contained only in the polymer constituting the shell layer without being contained in the polymer constituting the core layer, or may be contained in both the polymer constituting the core layer and the polymer constituting the shell layer.

[0026] By including a hydroxyl group-containing vinyl monomer as a constituent monomer in the shell layer, the polymer particles can be made reactive with the polyamide resin. As a result, the dispersibility of the polymer particles in the polyamide resin can be improved, and the effect of improving the impact strength of the polyamide resin by incorporating the polymer particles can be enhanced.

[0027] The hydroxyl group-containing vinyl monomer is not particularly limited, but a (meth)acrylic acid ester having a hydroxyalkyl group having 1 to 22 carbon atoms can be suitably used. The number of carbon atoms is preferably 1 to 18, more preferably 1 to 12, even more preferably 1 to 6, and particularly preferably 1 to 4. Specific examples include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. The hydroxyl group-containing vinyl monomer may be used alone or in combination of two or more.

[0028] The proportion of the hydroxyl group-containing vinyl monomer in the entire polymer particles is preferably 0.1% by weight or more and 10% by weight or less. When the proportion is within the above range, the effect of improving the impact strength of the polyamide resin by blending the polymer particles can be enhanced. The lower limit of the proportion is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, and even more preferably 1.0% by weight or more. Since the effect of improving the impact strength is particularly excellent, it is particularly preferably 2.0% by weight or more, and most preferably 3.0% by weight or more. The upper limit of the proportion is preferably 9.0% by weight or less, more preferably 8.0% by weight or less, even more preferably 7.0% by weight or less, and especially preferably 6.0% by weight or less.

[0029] (Volume average particle size of polymer particles) The volume average particle diameter of the polymer particles is 150 nm or more because excellent impact strength can be achieved. It is preferably 160 nm or more, more preferably 170 nm or more, and even more preferably 175 nm or more. On the other hand, when the particle diameter of the polymer particles is large, the polymerization reaction takes time and the productivity tends to decrease, so the volume average particle diameter is preferably 400 nm or less, more preferably 350 nm or less, even more preferably 300 nm or less, even more preferably 250 nm or less, and particularly preferably 200 nm or less. The volume average particle diameter of the polymer particles is a value measured by using a particle diameter measuring device in the state of the latex of the polymer particles, as shown in the example section. The volume average particle diameter of the polymer particles can also be calculated from a transmission electron microscope (TEM) image of the polyamide resin composition. The particle diameter of the polymer particles can be controlled by the type and amount of the polymerization initiator, chain transfer agent, redox agent, emulsifier, etc., the polymerization temperature, the polymerization time, etc.

[0030] (Method of Producing Polymer Particles) The polymer particles 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, that is, emulsion graft polymerization, is preferred.In emulsion graft polymerization, specifically, first, the latex of the polymer particles corresponding to the core layer is produced by emulsion polymerization, and then the monomer components for the shell layer, polymerization initiator, etc. are added to the latex to polymerize the monomer components.

[0031] The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be used. In addition, dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may be used. Among the above 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; alkalescents such as sodium dodecyl sulfate, sodium higher alcohol 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. Kyl sulfate ester salts; sodium alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; sodium dialkyl sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkyl naphthalene sulfonates; sodium alkyl diphenyl ether disulfonates; potassium alkyl phosphate salts; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalene sulfonate formalin condensates; polycarboxylate type polymer anions; sodium acyl (beef tallow) methyl taurate; sodium acyl (coconut) methyl taurate; sodium cocoyl isethionate; sodium α-sulfofatty acid ester salts; sodium amido ether sulfonate; oleyl sarcosine; sodium lauroyl sarcosine; rosin acid soap, etc.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] These emulsifiers (dispersants) may be used alone or in combination of two or more. The average particle size of the polymer particles can be controlled by adjusting the amount of the emulsifier used.

[0036] When the emulsion polymerization method is employed, known polymerization initiators, such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used as thermal decomposition initiators.

[0037] Also usable is a redox initiator obtained by using 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, in combination with at least one selected from the group consisting of a reducing agent, such as sodium formaldehyde sulfoxylate or glucose; a transition metal salt, such as iron (II) sulfate; a chelating agent, such as disodium ethylenediaminetetraacetate; or a phosphorus-containing compound, such as sodium pyrophosphate.

[0038] When a redox type initiator is used, polymerization can be performed even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set in a wide range, which is preferable. Among them, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as the redox type initiator. The amount of the initiator used, and the amount of the reducing agent, transition metal salt, chelating agent, etc. used when a redox type initiator is used, can be used within a known range. In addition, when polymerizing a polyfunctional monomer, a known chain transfer agent can be used within a known range. A surfactant can be additionally used, which is also within a known range.

[0039] 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.

[0040] The temperature during emulsion polymerization is not particularly limited as long as the emulsifier is uniformly dissolved in the solvent, but is, for example, 40 to 75°C, preferably 45 to 70°C, and more preferably 49 to 65°C.

[0041] When the polymer particles are produced by emulsion polymerization, for example, the polymer particles are coagulated by mixing a latex of the polymer particles with an acid such as hydrochloric acid or a divalent or higher metal salt such as calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, calcium acetate, etc., and then the polymer particles are heat-treated, dehydrated, washed, and dried according to a known method, whereby the polymer particles can be separated from the aqueous medium. The obtained polymer particles are preferably washed with water and / or an organic solvent.

[0042] Alternatively, a water-soluble organic solvent such as alcohol, e.g., methanol, ethanol, propanol, etc., or acetone, may be added to the latex of the polymer particles to precipitate the polymer particles, and the polymer particles may be separated from the solvent by centrifugation, filtration, etc., and then dried and isolated. Another method includes a method in which an organic solvent having a small water solubility, e.g., methyl ethyl ketone, is added to the latex of the polymer particles to extract the polymer particles in the latex into an organic solvent layer, and the organic solvent layer is separated and then mixed with water or the like to precipitate the polymer particles.

[0043] The latex of the polymer particles can also be directly powdered by spray drying. The obtained powder is preferably washed with water and / or an organic solvent. Alternatively, calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, etc., preferably as a solution such as an aqueous solution, can be added to the obtained powder, and the powder can be re-dried as necessary to obtain the same effect as the above washing.

[0044] (Modifier blend amount) The polyamide resin modifier comprising the polymer particles described above is used by blending with the polyamide resin, and has the effect of improving the impact strength of the polyamide resin. The blending amount of the modifier with respect to the polyamide resin can be appropriately set, but the ratio of the modifier to the total of the polyamide resin and the modifier is preferably 1 to 40% by weight. When the ratio of the modifier is within the above range, the effect of improving the impact strength of the polyamide resin by blending the modifier can be obtained while maintaining the physical properties specific to the polyamide resin. The ratio is more preferably 3 to 30% by weight, and further preferably 5 to 25% by weight.

[0045] (Polyamide resin) The polyamide resin is not limited as long as it is a polymer having an acid amide bond (-CONH-), and examples thereof include a polymer obtained by polycondensation of a diamine and a dicarboxylic acid, a polymer obtained by polycondensation of a diamine derivative such as diformyl and a dicarboxylic acid, a polymer obtained by polycondensation of a dicarboxylic acid derivative such as dimethyl ester and a diamine, a polymer obtained by reaction of a dinitrile or a diamide with formaldehyde, a polymer obtained by polyaddition of a diisocyanate and a dicarboxylic acid, a polymer obtained by self-condensation of an amino acid or its derivative, and a polymer obtained by ring-opening polymerization of a lactam. 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 and used.

[0046] Specific examples of polyamide resins include aliphatic polyamides such as nylon 4, nylon 6, nylon 66, 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. Among these, nylon 6, nylon 6,6, nylon 11, and nylon 12 are preferred from the viewpoint of versatility.

[0047] The diamine units constituting the polyamide resin may or may not contain 1,9-nonanediamine units and / or 2-methyl-1,8-octanediamine units, but the total content of 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units in the diamine units is preferably 0 mol% or more and less than 60 mol%, and more preferably 0 to 50 mol%.

[0048] (Other resins) The polyamide resin composition according to the present disclosure 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, and 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, and 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, relative to 100 parts by weight of the polyamide resin.

[0049] (Carbodiimide compounds) The polyamide resin composition according to the present disclosure preferably further contains a carbodiimide compound. By blending the carbodiimide compound together with the modifier composed of the polymer particles, the impact resistance improvement effect due to the blending of the modifier can be further enhanced. This is presumably because the carbodiimide group has reactivity with the hydroxyl group in the shell layer of the polymer particles, and the terminal carboxylic acid group and amino group of the polyamide resin, so that the carbodiimide compound functions as a compatibilizer, and the dispersibility of the polymer particles in the polyamide resin can be further improved.

[0050] The carbodiimide compound preferably has a skeleton represented by the following chemical formula (1). (-RN=C=N-) n (1) In the above chemical formula, n R's may be the same or different and each represent a divalent aliphatic hydrocarbon group having 1 to 18 carbon atoms, a divalent heterocyclic group having 3 to 12 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 14 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 13 carbon atoms, or a terminal hydroxyl group. n is an integer of 1 to 15.

[0051] Examples of the carbodiimide compound in which n is 1 in the chemical formula (1) include dicyclohexylcarbodiimide, diisopropylcarbodiimide, N,N'-phenylcarbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-di-2,6-diisopropylphenylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and its hydrochloride, 1-ethyl-3-(tert-butyl)carbodiimide (BEC), 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide (CMC), and the like.

[0052] A linear polymer called polycarbodiimide is known as a carbodiimide compound represented by the above chemical formula (1) in which n is 2 or more. Examples of diisocyanates that are raw materials for polycarbodiimides include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and mixtures thereof.

[0053] Examples of the aromatic diisocyanate include 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, 2,6-isopropylphenyl diisocyanate, and 1,3,5-triisopropylbenzene-2,4-diisocyanate.

[0054] Examples of the aliphatic diisocyanate include hexamethylene diisocyanate, etc. Examples of the alicyclic diisocyanate include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexane diisocyanate, etc.

[0055] The carbodiimide compound can be produced, for example, by using a monoisocyanate or diisocyanate as a raw material and carrying out a decarboxylation condensation reaction in the presence of an organophosphorus compound or an organometallic compound at a temperature of about 70° C. or higher in the absence of a solvent or in an inert solvent.

[0056] In the carbodiimide compound, R preferably represents an aliphatic hydrocarbon group. The aliphatic hydrocarbon group is preferably a linear hydrocarbon group. From the viewpoint of safety and ease of handling, the molecular weight of the carbodiimide compound is preferably 100 or more and 100,000 or less, and more preferably 500 or more and 10,000 or less.

[0057] Commercially available examples of the carbodiimide compound include products manufactured by Nisshinbo Chemical Inc., such as Carbodilite HMV-5CA-LC, Carbodilite LA-1 (poly(4,4'-dicyclohexylmethane carbodiimide)), Carbodilite HMV-8CA, and Carbodilite HMV-15CA containing no isocyanate groups, and products manufactured by Rhein Chemie include Stavaxol P (poly(1,3,5-triisopropylbenzene) polycarbodiimide), Stavaxol P-400 (poly(1,3,5-triisopropylbenzene) polycarbodiimide), and Stavaxol I (N,N'-di-2,6-diisopropylphenylcarbodiimide).

[0058] The content of the carbodiimide compound may be appropriately set, but from the viewpoint of the impact resistance improving effect, it is preferably 0.1 to 2.0 parts by weight, more preferably 0.2 to 1.5 parts by weight, and even more preferably 0.3 to 1.0 parts by weight, per 100 parts by weight of the polyamide resin composition.

[0059] (Other additives) The polyamide resin composition according to the present disclosure may appropriately contain additives that can be blended into general thermoplastic resin compositions. Such additives are not particularly limited, but examples thereof include flame retardants, flame retardant assistants, 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.

[0060] From the viewpoint of improving impact strength, the polyamide resin composition according to the present disclosure 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 them, glass fiber, carbon fiber, and metal fiber are preferred, and glass fiber is more preferred, because they have a high effect of improving impact strength. The reinforcing material may be used alone or in combination of two or more kinds.

[0061] The amount of the reinforcing material to be added can be appropriately set, but is preferably 10 to 60 parts by weight, more preferably 15 to 50 parts by weight, and even more preferably 20 to 40 parts by weight, per 100 parts by weight of the polyamide resin composition.

[0062] (Production method of the composition) The method for producing the polyamide resin composition is not particularly limited, and a general method for producing a thermoplastic resin composition can be applied. For example, the raw materials are mixed using a Henschel mixer or a tumbler mixer, and then melt-kneaded to obtain the polyamide resin composition. For the melt-kneading, a kneading machine 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.

[0063] The polyamide resin composition can be molded into a predetermined shape to obtain a molded article. The molding method is not particularly limited, and examples of the molding method that can be used include injection molding, extrusion molding, blow molding, calendar molding, inflation molding, rotational molding, and press molding.

[0064] (Application) Polyamide resin compositions and molded articles thereof are widely used in a wide range of applications, including 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, bearings, and resistance components. Examples of applications include, but are not limited to, mechanical applications such as pressure 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, diving snorkels and the like; packaging materials and container applications such as shrink wrapping film, food packaging film, alcoholic beverage bottles, pesticide bottles and the like; everyday applications such as toothbrushes, chair legs and armrests, combs, knives and forks and the like; and medical applications such as medical catheters and pipes, medical packs and sutures and the like. EXAMPLES

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0066] (Average particle size of polymer particles) The average particle size of the polymer particles was measured as a volume average particle size in the state of the polymer particle latex using a Nanotrac Wave manufactured by Nikkiso Co., Ltd. as a measuring device.

[0067] (Polymerization conversion rate) A part of the obtained latex was sampled and weighed, and dried in a hot air dryer at 120℃ for 1 hour. The weight after drying was weighed as the solid content. The ratio of the weighing results before and after drying was calculated as the solid content ratio in the latex. Finally, the polymerization conversion rate was calculated by the following formula using this solid content ratio. Formula: Polymerization conversion rate = (total weight of raw materials charged x solid component ratio - total weight of raw materials other than monomers) / weight of charged monomer x 100 (%)

[0068] <Production method of polybutadiene rubber latex (core layer) (R-1)> In a pressure-resistant polymerization reactor, 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 were added, and the mixture was thoroughly degassed with stirring to remove oxygen. Then, 100 parts by weight of butadiene (hereinafter referred to as Bd) was added to the system, and the temperature was raised to 45°C. Then, 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 was added. At 20 hours after the start of polymerization, the remaining monomers were removed by volatilization under reduced pressure to terminate the polymerization, and polybutadiene rubber latex (R-1) consisting mainly of polybutadiene rubber was obtained. The volume average particle size of the polybutadiene rubber particles in the obtained latex (R-1) was appropriately adjusted by changing the initial amount of sodium dodecylbenzenesulfonate added.

[0069] As a representative method for producing the polymer particle latex, the procedure for producing the polymer particle latex in Example 1 is shown below. The polymer particles in Examples 2 and 3 and Comparative Example 1 were produced by changing the monomer composition of the shell layer according to the description in Table 1, but the production procedure was in accordance with the description below for Example 1.

[0070] <Production method of polymer particle latex in Example 1> In a glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier adding device, 30 parts by weight of deionized water and polybutadiene rubber latex (R-1) were charged so that the solid content was 78 parts by weight, and the temperature was raised 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 18.45 parts by weight of methyl methacrylate (hereinafter referred to as MMA), 2.05 parts by weight of butyl acrylate (hereinafter referred to as BA), 1.5 parts by weight of 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA), and 0.024 parts by weight of t-butyl hydroperoxide was added thereto over a period of 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%.

[0071] (Obtaining white resin powder of polymer particles) 760 parts by weight of deionized water and 3.3 parts by weight of a 25% by weight aqueous calcium chloride solution were heated to 60°C while stirring, and polymer particle latex containing 3.0 parts by weight of IRGANOX-1076 [n-octadecyl-3-(3',5',di-t-butyl-4'-hydroxyphenyl)propionate], a hindered phenol-based antioxidant, was added to obtain a slurry containing coagulated latex particles. The obtained slurry was heated to 90°C, dehydrated, and dried to obtain a white resin powder of core-shell type polymer particles. This was used in the production of the following polyamide resin composition.

[0072] (Production of polyamide resin composition) According to the following description, pellets and test pieces composed of a polyamide resin, a white resin powder of polymer particles, and a composition containing a carbodiimide compound in some cases were prepared, and the Izod impact strength, MFR, and tensile properties were measured, and the results are shown in each table. However, in Reference Example 1, the white resin powder of polymer particles was not used, and the polyamide resin alone was evaluated.

[0073] [Test piece preparation conditions for Tables 1 and 2] (a) Polyamide 6 resin (Durethan B29 manufactured by Lanxess): Amount as shown in Table 1 or 2 (b) Core-shell type polymer particles: amount shown in Table 1 or 2 (c) Carbodiimide compound (Carbodilite HMV-5CA-LC, manufactured by Nisshinbo Chemical Co., Ltd.): the amount shown in Table 1 or 2 (d) Hindered phenol-based antioxidant (Irganox 1010 manufactured by BASF): 0.2 parts by weight (e) Phosphorus-based processing stabilizer (Irgafos 168 manufactured by BASF): 0.1 parts by weight

[0074] The mixture of (a), (b), (c), (d) and (e) was mixed in a twin-screw extruder (TEX44SS manufactured by The Japan Steel Works, Ltd.) heated to a barrel temperature of 230 to 260°C and at a screw rotation speed of 100 rpm to obtain extruded pellets.

[0075] The pellets were dried in a dryer at 80°C for 12 hours to sufficiently reduce the moisture content, and then the test pieces used in Tables 1 and 2 were produced using an injection molding machine (FAS100B, manufactured by Fanuc Corporation) at a molding temperature of 270 to 290°C and a mold temperature of 80°C.

[0076] [Test piece preparation conditions for Table 3] (a) 30% glass fiber reinforced polyamide 6,6 resin (CM3006G-30 manufactured by Toray Industries, Inc.): the amount shown in Table 3 (b) Core-shell type polymer particles: amount shown in Table 3 (c) Carbodiimide compound (Carbodilite HMV-5CA-LC, manufactured by Nisshinbo Chemical Co., Ltd.): the amount shown in Table 3 (d) Hindered phenol-based antioxidant (Irganox 1010 manufactured by BASF): 0.2 parts by weight (e) Phosphorus-based processing stabilizer (Irgafos 168 manufactured by BASF): 0.1 parts by weight

[0077] The mixture of (a), (b), (c), (d) and (e) was mixed in a twin-screw extruder (TEX44SS manufactured by The Japan Steel Works, Ltd.) heated to a barrel temperature of 240 to 290°C at a screw rotation speed of 100 rpm to obtain extruded pellets.

[0078] The pellets were dried in a dryer at 80°C for 12 hours to sufficiently reduce the moisture content, and then test pieces were produced using an injection molding machine (FAS100B manufactured by Fanuc Corporation) at a molding temperature of 270 to 290°C and a mold temperature of 95°C.

[0079] (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 as described above, was measured in an absolute dry state at -30°C and 23°C according to the method according to ASTM D256. The results are shown in the tables.

[0080] (Tensile properties) The tensile properties of the ASTM D638-1 type test pieces having a thickness of 3.2 mm prepared by the above-mentioned method were measured in an absolute dry state at a test speed of 50 mm / min. and at 23°C according to the method in accordance with the ASTM D638 standard. The results are shown in the tables.

[0081] (MFR) The extruded 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 at a measurement temperature of 280°C and a load of 5 kg according to JIS K7210 Method A. The results are shown in the tables.

[0082] [Table 1]

[0083] From Table 1, it can be seen that in Examples 1 to 3, in which polymer particles containing a hydroxyl group-containing vinyl monomer in the shell layer were used, the Izod impact strength values ​​measured at 23°C were larger and impact resistance was superior compared to Comparative Example 1, in which polymer particles not containing a hydroxyl group-containing vinyl monomer were used. Furthermore, it can be seen from Examples 1 to 3 that the impact resistance improved and the tensile break strain value increased as the content of the hydroxyl group-containing vinyl monomer increased.

[0084] [Table 2]

[0085] From Table 2, it can be seen that in Example 4, in which a carbodiimide compound was used in combination with polymer particles containing a hydroxyl group-containing vinyl monomer in the shell layer, the numerical value of the Izod impact strength measured at 23 ° C. is very large compared to Example 1, in which a carbodiimide compound was not used in combination. On the other hand, in Comparative Example 2, in which a carbodiimide compound alone was used without blending polymer particles containing a hydroxyl group-containing vinyl monomer in the shell layer, the impact resistance was not improved compared to Reference Example 1. Therefore, it can be seen that the use of a carbodiimide compound alone does not show an improvement effect on impact resistance, and that the impact resistance is specifically improved by combining a carbodiimide compound with polymer particles containing a hydroxyl group-containing vinyl monomer in the shell layer. In addition, it can be seen that in Example 4, in addition to impact resistance, the tensile yield stress, tensile breaking stress, and tensile breaking strain are also improved compared to Example 1.

[0086] [Table 3]

[0087] Table 3 shows the results for a system in which glass fiber, a reinforcing material, is blended with a polyamide resin. Here again, it is seen that the impact resistance is improved by blending polymer particles containing a hydroxyl group-containing vinyl monomer in the shell layer, and that the impact resistance is further improved by using the polymer particles in combination with a carbodiimide compound. In addition, it is seen that in Example 6, in addition to the impact resistance, the tensile yield stress, tensile break stress, and tensile break strain are also improved compared to Example 5.

Claims

1. A modifier for polyamide resins comprising polymer particles, The polymer particles have a core-shell structure consisting of a shell layer and one or more core layers, The polymer particles have a volume average particle size of 150 nm or more, At least one of the core layers is made of polybutadiene or poly(butadiene-styrene); the shell layer is composed of a polymer of 50% by weight or more of a methacrylic acid ester monomer and 0 to 50% by weight of another monomer copolymerizable with the methacrylic acid ester monomer; the polymer constituting the shell layer contains a hydroxyl group-containing vinyl monomer as a constituent monomer, A modifier for polyamide resins, wherein the weight ratio of the shell layer to the entire polymer particles is 10 to 30% by weight.

2. 2. The polyamide resin modifier according to claim 1, wherein the proportion of the hydroxyl group-containing vinyl monomer in the entire polymer particles is 0.1% by weight or more and 10% by weight or less.

3. The modifier for polyamide resins according to claim 1 or 2, wherein the core layer has a refractive index of 1.47 or more.

4. The polyamide resin has a total content of 1,9-nonanediamine units and 2-methyl-1,8-octanediamine units in the diamine units constituting the polyamide resin of 0 mol% or more and less than 60 mol%. The polyamide resin modifier according to any one of claims 1 to 3.

5. A polyamide resin composition comprising a polyamide resin and the polyamide resin modifier according to any one of claims 1 to 4, wherein the proportion of the modifier relative to the total of the polyamide resin and the modifier is 1 to 40% by weight.

6. The polyamide resin composition according to claim 5, further comprising 0.1 to 2.0 parts by weight of a carbodiimide compound based on 100 parts by weight of the polyamide resin composition.

7. The polyamide resin composition according to claim 5 or 6, further comprising 10 to 60 parts by weight of a reinforcing material based on 100 parts by weight of the polyamide resin composition.

8. A pellet comprising the polyamide resin composition according to any one of claims 5 to 7.

9. A molded article comprising the polyamide resin composition according to any one of claims 5 to 7.

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