Method for manufacturing a resin composition, and method for manufacturing a molded article

Abstract

To provide a method for producing a resin composition which gives a resin composition excellent in flexibility and low in compression set, and a method for producing a molding using the same.SOLUTION: The present invention relates to the method for producing a resin composition which includes a step of kneading a component (A): 100 pts.wt. of a block copolymer comprising a styrenic polymer block and an isobutylene-based polymer block, a component (B): 100-250 pts.wt. of a styrenic thermoplastic elastomer other than the component A, a component (C): 1-50 pts.wt. of polypropylene, and a component (D): 30-200 pts.wt. of a polybutene oil. The kneading is performed at 160-200°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin composition containing a styrene-based thermoplastic elastomer, and a method for producing a molded article using the same. [Background technology]

[0002] Traditionally, cross-linked rubber and the like have been widely used as elastic polymer materials. However, cross-linked rubbers have poor processability and are generally difficult to recycle. Therefore, in recent years, thermoplastic elastomers have been developed that can be easily manufactured using general-purpose melt molding technologies such as hot press molding, injection molding, and extrusion molding, just like ordinary thermoplastic resins. Such thermoplastic elastomers include olefin-based, urethane-based, ester-based, and styrene-based types, but styrene-based thermoplastic elastomers are used because they have excellent flexibility and rubber elasticity. For example, Patent Document 1 describes thermoplastic elastomer compositions using hydrogenated styrene-isoprene-styrene copolymers and styrene-isobutylene-styrene copolymers. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-145399 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the compression set of conventional resin compositions using styrene-based thermoplastic elastomers, as described in Patent Document 1, etc., is subject to further improvement.

[0005] To solve the problems of the past, the present invention provides a method for producing a resin composition that is highly flexible and has low compression set, and a method for producing a molded article using the same. [Means for solving the problem]

[0006] The present invention relates to a method for producing a resin composition, comprising the step of kneading (A) 100 parts by weight of a block copolymer consisting of a styrene polymer block and an isobutylene polymer block, (B) 100 to 250 parts by weight of a styrene thermoplastic elastomer other than the above A component, (C) 1 to 50 parts by weight of polypropylene, and (D) 30 to 200 parts by weight of polybutene oil, wherein the kneading is carried out at 160 to 200°C.

[0007] The present invention relates to a method for manufacturing a resin molded article, comprising the steps of manufacturing a resin composition using the method for manufacturing the resin composition, and molding the resin composition. [Effects of the Invention]

[0008] According to the manufacturing method of the present invention, it is possible to provide a resin composition that is highly flexible and has low compression set. Furthermore, by using the resin composition obtained by the manufacturing method of the present invention, it is possible to produce molded articles that have good moldability, excellent flexibility, and low compression set. [Modes for carrying out the invention]

[0009] The inventors of the present invention have conducted extensive research to solve the aforementioned problems. Normally, the compression set of a resin composition containing a thermoplastic elastomer is influenced by the components constituting the resin composition and their proportions, but the inventors of the present invention have found that the melt-kneading temperature during the production of the resin composition has a significant influence on the properties of the resin composition, such as the compression set. Specifically, in Patent Document 1, a thermoplastic elastomer composition is produced by melt-kneading each component, such as hydrogenated styrene-isoprene-styrene copolymer or styrene-isobutylene-styrene copolymer, under cylinder temperature conditions of 180 to 240°C, but there was a problem that the compression set increased when the temperature during melt-kneading was high. Therefore, the present invention provides a resin composition that maintains the excellent flexibility of the styrene-based thermoplastic elastomer while having a low compression set, by melt-kneading predetermined amounts of (A) component: a block copolymer consisting of a styrene-based polymer block and an isobutylene-based polymer block, (B) component: a styrene-based thermoplastic elastomer other than the above A component, (C) component: polypropylene, and (D) component: polybutene oil at 160 to 200°C.

[0010] In this specification, when a numerical range is indicated by "~", the numerical range includes both endpoints (upper and lower limits). For example, the numerical range "X~Y" includes both endpoints, X and Y. Furthermore, when multiple numerical ranges are described in this specification, they shall include numerical ranges formed by appropriately combining the upper and lower limits of different numerical ranges.

[0011] (Method for manufacturing resin compositions) A method for producing one or more resin compositions of the present invention includes the step of kneading components (A), (B), (C), and (D) at 160 to 200°C.

[0012] [(A) component] Component (A) is a block copolymer consisting of a styrene-based polymer block and an isobutylene-based polymer block.

[0013] The styrene polymer block contains 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more of styrene monomers, and is particularly preferably composed of 100% by weight of styrene monomers. Examples of styrene monomers include styrene, α-methylstyrene, β-methylstyrene, p-methylstyrene, t-butylstyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, indene, divinylbenzene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, and vinylpyridine. These may be used individually or in combination of two or more. From a balance of cost, physical properties, and productivity, one or more selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and indene are preferred. In the styrene-based polymer block, the monomers other than the styrene-based monomer can be any monomer that can polymerize with the styrene-based monomer and are not particularly limited, but examples include aromatic vinyl compounds other than styrene-based monomers, olefin compounds, vinyl ether compounds, β-pinene, etc. The monomers other than the styrene-based monomer may be used individually or in combination of two or more.

[0014] The isobutylene polymer block contains 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more of isobutylene, and is particularly preferably composed of 100% by weight of isobutylene. In the isobutylene polymer block, the monomer other than isobutylene may be any monomer that can polymerize with isobutylene and is not particularly limited, but examples include olefin compounds other than isobutylene, aromatic vinyl compounds, diene compounds, vinyl ether compounds, β-pinene, etc. The monomer other than isobutylene may be used alone or in combination of two or more.

[0015] In component (A), from the perspective of the balance between physical properties and processability, the weight ratio of the styrene-based polymer block to the isobutylene-based polymer block (styrene-based polymer block: isobutylene-based polymer block) is preferably 10:90 to 50:50 by weight, more preferably 15:85 to 45:55, and even more preferably 20:80 to 40:60. In the present specification, the content of the styrene-based polymer block or the isobutylene-based polymer block in component (A) can be measured by nuclear magnetic resonance spectroscopy.

[0016] The weight average molecular weight of component (A) is preferably 50,000 to 200,000, more preferably 60,000 to 180,000, and even more preferably 70,000 to 160,000. When the weight average molecular weight of component (A) is 50,000 or more, compression set can be reduced. When the weight average molecular weight of component (A) is 200,000 or less, the moldability becomes good. In the present specification, the average molecular weight can be measured by gel permeation chromatography (GPC). The GPC measurement is performed using chloroform as the mobile phase, the measurement is carried out using a polystyrene gel column, and the weight average molecular weight and number average molecular weight can be determined in terms of polystyrene.

[0017] Component (A) may be a diblock or a triblock. However, from the perspective of heat resistance and tensile properties, it is preferably a triblock composed of two styrene-based polymer blocks and one isobutylene-based polymer block, and more preferably a styrene-isobutylene-styrene block copolymer.

[0018] In the resin composition of one or more embodiments of the present invention, the content of component (A) may be 15 to 45% by weight, may be 20 to 40% by weight, or may be 25 to 35% by weight.

[0019] There are no particular restrictions on the method for producing a block copolymer composed of a styrene-based polymer block and an isobutylene-based polymer block of component (A). For example, it can be obtained by polymerizing a monomer mainly composed of isobutylene and a monomer mainly composed of a styrene-based monomer in the presence of a compound represented by the following general formula (1).

[0020]

Chemical formula

[0021] The compound represented by the above general formula (1) serves as a polymerization initiator, generates a carbocation in the presence of a Lewis acid or the like, and is considered to be the starting point of cationic polymerization.

[0022] Examples of compounds represented by the above general formula (1) include (1-chloro-1-methylethyl)benzene [C6H5C(CH3)2Cl], 1,4-bis(1-chloro-1-methylethyl)benzene [1,4-Cl(CH3)2CC6H4C(CH3)2Cl], 1,3-bis(1-chloro-1-methylethyl)benzene [1,3-Cl(CH3)2CC6H4C(CH3)2Cl], 1,3,5-tris(1-chloro-1-methylethyl)benzene [1,3,5-(ClC(CH3)2)3C6H3], and 1,3-bis(1-chloro-1-methylethyl)-5-(tert-butyl)benzene [1,3-(C(CH3)2Cl)2-5-(C(CH3)3)C6H3]. In particular, one or more selected from the group consisting of 1,4-bis(1-chloro-1-methylethyl)benzene, 1,3-bis(1-chloro-1-methylethyl)benzene, and 1,3-bis(1-chloro-1-methylethyl)-5-(tert-butyl)benzene are preferred, and one or more bis(1-chloro-1-methylethyl)benzenes selected from the group consisting of 1,4-bis(1-chloro-1-methylethyl)benzene and 1,3-bis(1-chloro-1-methylethyl)benzene are more preferred. Note that bis(1-chloro-1-methylethyl)benzene is also called bis(α-chloroisopropyl)benzene, bis(2-chloro-2-propyl)benzene, or dicumyl chloride, and 1,4-bis(1-chloro-1-methylethyl)benzene is also called p-dicumyl chloride.

[0023] In the polymerization reaction described above, a Lewis acid catalyst is generally used. Such a Lewis acid catalyst is not particularly limited as long as it can be used in cationic polymerization, and examples include metal halides such as TiCl4, TiBr4, BCl3, BF3, BF3·OEt2, SnCl4, AlCl3, AlBr3; or metal compounds having both halogen atoms and alkoxy groups on the metal, such as TiCl3(OiPr), TiCl2(OiPr)2, TiCl(OiPr)3; Et2AlCl, EtAlCl2, Me2AlCl, MeAlCl2, Et 1.5 AlCl 1.5 Me 1.5 AlCl 1.5Examples include organometallic halides such as the following. Among them, considering catalytic activity and availability, TiCl4, BCl3, SnCl4, TiCl3(OiPr), TiCl2(OiPr)2, TiCl(OiPr)3, EtAlCl2, Et 1.5 AlCl 1.5 One or more Lewis acids selected from the group consisting of are preferred.

[0024] The amount of Lewis acid catalyst used is not particularly limited. It can be arbitrarily set in consideration of the polymerization characteristics and polymerization concentration of the monomer used, as well as the exothermic behavior. Preferably, it is used in a range of 0.1 to 200 times the amount of the polymerization initiator in moles, and more preferably in a range of 0.2 to 100 times.

[0025] In polymerization reactions, it is preferable to include electron donors. The presence of electron donors tends to make it easier to obtain polymers with a narrow molecular weight distribution and controlled structure.

[0026] Examples of electron donors include pyridine compounds, amine compounds, amide compounds, sulfoxide compounds, ester compounds, and metal compounds having oxygen atoms bonded to metal atoms. More specifically, compounds with a donor number of 15 to 60, defined as a parameter representing the strength of electron donation, are preferably used.

[0027] Examples of pyridine compounds include 2,6-di-tert-butylpyridine, 2-tert-butylpyridine, 2,4,6-trimethylpyridine, 2,6-dimethylpyridine, 2-methylpyridine, and pyridine.

[0028] Examples of amine compounds include diethylamine, trimethylamine, triethylamine, tributylamine, and N,N-dimethylaniline.

[0029] Examples of amide compounds include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, and hexamethylphosphate triamide.

[0030] Examples of sulfoxide compounds include dimethyl sulfoxide.

[0031] Examples of ester compounds include methyl acetate, ethyl acetate, and butyl acetate.

[0032] Examples of metallic compounds include Ti(OiPr)4.

[0033] In particular, from the viewpoint of suppressing side reactions and availability, one or more electron donors selected from the group consisting of 2-methylpyridine, 2,6-dimethylpyridine, triethylamine, N,N-dimethylformamide, N,N-dimethylacetamide, and Ti(OiPr)4 are preferred.

[0034] The amount of electron donor used is not particularly limited. It can be arbitrarily set in consideration of the polymerization characteristics and polymerization concentration of the monomer used, as well as the exothermic behavior. Preferably, it is used in a range of 0.01 to 100 times the amount of the polymerization initiator in moles, and more preferably in a range of 0.1 to 50 times.

[0035] Polymerization reactions can be carried out in organic solvents as needed. The organic solvent is not particularly limited as long as it is an organic solvent commonly used in cationic polymerization; halogenated hydrocarbons; non-halogenated hydrocarbons such as aliphatic hydrocarbons and aromatic hydrocarbons; or mixtures thereof can be used.

[0036] Examples of halogenated hydrocarbons that can be used include methyl chloride, methylene chloride, chloroethane, dichloroethane, 1-chloropropane, 1-chloro-2-methylpropane, 1-chlorobutane (also called butyl chloride), 1-chloro-2-methylbutane, 1-chloro-3-methylbutane, 1-chloro-2,2-dimethylbutane, 1-chloro-3,3-dimethylbutane, 1-chloro-2,3-dimethylbutane, 1-chloropentane, 1-chloro-2-methylpentane, 1-chloro-3-methylpentane, 1-chloro-4-methylpentane, 1-chlorohexane, 1-chloro-2-methylhexane, 1-chloro-3-methylhexane, 1-chloro-4-methylhexane, 1-chloro-5-methylhexane, 1-chloroheptane, 1-chlorooctane, 2-chloropropane, 2-chlorobutane, 2-chloropentane, 2-chlorohexane, 2-chloroheptane, 2-chlorooctane, chlorobenzene, and others. These can be used individually or in combination of two or more types.

[0037] Examples of aliphatic hydrocarbons include butane, pentane, hexane, heptane, octane, nonane, decane, 2-methylpropane, 2-methylbutane, 2,3,3-trimethylpentane, 2,2,5-trimethylhexane, cyclohexane, methylcyclohexane, ethylcyclohexane, and paraffinic oil. These can be used individually or in combination of two or more.

[0038] Examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, propylbenzene, and butylbenzene. These can be used individually or in combination of two or more.

[0039] In particular, from the viewpoint of solubility and economic efficiency, it is preferable to use a mixed organic solvent of halogenated hydrocarbons having 3 to 5 carbon atoms and aliphatic hydrocarbons. A combination of one or more halogenated hydrocarbons selected from the group consisting of 1-chloropropane, 1-chlorobutane, and 1-chloropentane, and one or more non-halogenated hydrocarbons selected from the group consisting of pentane, hexane, heptane, cyclohexane, methylcyclohexane, and ethylcyclohexane is especially preferred from the viewpoint of solubility, economic efficiency, reactivity, and ease of distillation in the post-treatment process.

[0040] The organic solvent is preferably set to such a concentration of 1 to 50% by weight, and more preferably to 1 to 30% by weight, taking into consideration the viscosity of the polymer solution and the ease of heat removal.

[0041] Generally, cationic polymerization is known to be inhibited by the presence of water. Therefore, it is desirable to remove water from the organic solvent before use. As a method of removing water, it is possible to use methods that involve adding and contacting common dehydrating agents such as calcium chloride or molecular sieves.

[0042] There are no particular restrictions on the polymerization temperature, but it is preferable to carry out polymerization at a temperature of -100 to 50°C, and more preferably at -85 to 0°C from the viewpoint of energy cost and the stability of the polymerization reaction.

[0043] The polymerization time is not particularly limited, but for example, from the viewpoint of productivity, 1 minute to 48 hours is preferred, 10 minutes to 36 hours is more preferred, and 30 minutes to 24 hours is even more preferred.

[0044] In the method for producing the polymer, the polymerization step is carried out by a cationic polymerization method using carbocations as the growing species, as described above. Unless otherwise specified in this specification, known or conventional methods may be applied to carry out cationic polymerization.

[0045] The method for producing a polymer may include other steps in addition to the polymerization step. Other steps include, for example, removing organic solvents, water, etc., from the polymer solution (dope) obtained in the polymerization step. The method for removing organic solvents and water from the dope is not particularly limited, and known or conventional methods can be selected and implemented. The removed organic solvent may be purified as appropriate. One method for more highly purifying organic solvents used in polymerization is distillation. Distillation can remove almost all impurities with different boiling points. Distillation can be performed by batch distillation or continuous distillation. For example, in batch distillation, low-boiling point impurities can be removed by withdrawing the top distillate at the beginning of the distillation process, and high-boiling point impurities can be removed by withdrawing the bottom distillate after distillation. In the case of continuous distillation, impurities can be removed using one or more distillation columns, depending on the type of impurities to be removed.

[0046] [(B) Component] Component (B) is a styrene-based thermoplastic elastomer other than component (A). 100 to 250 parts by weight of component (B) are used per 100 parts by weight of component (A). A component of 100 parts by weight or more results in a lower compression set. A component of 250 parts by weight or less results in good moldability. Preferably, component (B) is 100 to 250 parts by weight per 100 parts by weight of component (A), more preferably 110 to 225 parts by weight, and even more preferably 120 to 200 parts by weight.

[0047] Component (B) can be, for example, a block copolymer containing a styrene-based polymer block, and specifically, a polymer block containing a styrene-based polymer block and an olefin-based polymer block can be used. The styrene-based polymer block may be the same as that in the case of component (A).

[0048] The olefin polymer block contains 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and even more preferably 90% by weight or more, of olefin monomers other than isobutylene, and it is particularly preferable that it consists of 100% by weight of olefin monomers other than isobutylene. Examples of olefin monomers other than isobutylene include monoolefin monomers such as ethylene, propylene, and 1-butene; and diolefin (conjugated diene) monomers such as butadiene and isoprene. The olefin monomers other than isobutylene may be used individually or in combination of two or more. In the olefin polymer block, monomers other than olefin monomers are not particularly limited as long as they can be polymerized with olefin monomers, but examples include aromatic vinyl compounds, diene compounds, vinyl ether compounds, and β-pinene. The monomers other than olefins may be used individually or in combination of two or more.

[0049] Component (B) is preferably a hydrogenated styrene-based thermoplastic elastomer from the viewpoint of gas barrier properties such as water vapor. Examples of hydrogenated styrene-based thermoplastic elastomers include polymer blocks consisting of a styrene-based polymer block and a conjugated diene-based polymer block (e.g., a butadiene-based polymer block, an isoprene polymer block, a butadiene / isoprene polymer block, etc.), in which some or all of the carbon-carbon double bonds in the conjugated diene-based polymer block are hydrogenated. The hydrogenation rate in the conjugated diene-based polymer block is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. The hydrogenated styrene-based thermoplastic elastomer may have one or more functional groups such as carboxyl groups, hydroxyl groups, acid anhydride groups, amino groups, and epoxy groups in the molecular chain and / or at the molecular terminals, as long as it does not hinder the effects of the present invention.

[0050] In component (B), from the viewpoint of balancing physical properties and processability, the weight ratio of styrene polymer blocks to olefin polymer blocks (styrene polymer blocks:olefin polymer blocks) is preferably 10:90 to 50:50, more preferably 15:85 to 45:55, and even more preferably 20:80 to 40:60. In this specification, the content of styrene polymer blocks or olefin polymer blocks in component (B) can be measured by nuclear magnetic resonance spectroscopy.

[0051] The weight-average molecular weight of component (B) is preferably 150,000 to 600,000, more preferably 200,000 to 550,000, and even more preferably 250,000 to 500,000. When the weight-average molecular weight of component (B) is 150,000 or more, the compression set can be reduced. When the weight-average molecular weight of component (B) is 600,000 or less, the moldability is good.

[0052] (B) Specifically, examples of components include thermoplastic elastomers such as styrene-butadiene copolymer (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylenebutylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylenepropylene-styrene block copolymer (SEPS), and hydrogenated styrene (butadiene / isoprene) styrene copolymer. These thermoplastic elastomers may be used individually or in combination of two or more types.

[0053] In the resin compositions of one or more embodiments of the present invention, the content of component (B) may be 20 to 70% by weight, 25 to 60% by weight, or 30 to 50% by weight.

[0054] [(C) component] Component (C) is polypropylene. Polypropylene is effective in improving the moldability of the resin composition and reducing the compression set. 1 to 50 parts by weight of polypropylene is used per 100 parts by weight of component (A). Having 1 part by weight or more of polypropylene improves the moldability of the resin composition. Also, having 50 parts by weight or less of polypropylene reduces the compression set of the resin composition. Preferably, component (C) is 3 to 40 parts by weight, more preferably 8 to 35 parts by weight, and even more preferably 10 to 25 parts by weight per 100 parts by weight of component (A).

[0055] Polypropylene may be a homopolymer consisting of 100 mol% propylene, or a copolymer of propylene with a propylene content of 50 mol% or more and an α-olefin other than propylene. The α-olefin may have 2, 4-20 carbon atoms, and specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene-1, etc., and one type may be used alone or two or more types may be used in combination. The copolymer may be random polypropylene or block polypropylene. Random polypropylene is preferred in terms of tensile properties and moldability of the resin composition.

[0056] In the resin compositions of one or more embodiments of the present invention, the content of component (C) may be 0.1 to 20% by weight, 1 to 15% by weight, or 2 to 10% by weight.

[0057] [(D) component] Component (D) is polybutene oil. Polybutene oil functions as a softening agent, is effective in improving the flexibility of the resin composition, and has high barrier properties such as gas barrier properties. With respect to 100 parts by weight of component (A), 30 to 200 parts by weight of polybutene oil is used. When the polybutene oil is 30 parts by weight or more, the hardness of the resin composition decreases and the flexibility increases. Also, when the polybutene oil is 200 parts by weight or less, the mechanical strength, moldability, and gas barrier properties are improved. With respect to 100 parts by weight of component (A), component (C) is preferably 40 to 180 parts by weight, more preferably 50 to 170 parts by weight, and even more preferably 60 to 150 parts by weight.

[0058] The polybutene oil is not particularly limited, and a high molecular weight substance in an oily state at room temperature (20 ± 5°C) mainly composed of isobutylene can be appropriately used.

[0059] The number average molecular weight of the polybutene oil is not particularly limited, but is preferably 300 to 20,000, and particularly preferably 500 to 10,000. When the number average molecular weight of the polybutene oil is 300 or more, the heat resistance of the resin composition is improved. When the number average molecular weight of the polybutene oil is 20,000 or less, the moldability of the resin composition is improved.

[0060] The kinematic viscosity of the polybutene oil at 40°C is not particularly limited, but for example, it is preferably 3,000 to 20,000 mm 2 / s, more preferably 4,000 to 18,000 mm 2 / s, and even more preferably 5,000 to 16,000 mm 2 / s. In this specification, the kinematic viscosity of the polybutene oil at 40°C can be measured in accordance with JIS Z 8803:2011.

[0061] In the resin composition of one or more embodiments of the present invention, the content of component (D) may be 5 to 55% by weight, may be 10 to 45% by weight, or may be 15 to 35% by weight.

[0062] [Other ingredients] In one or more embodiments of the present invention, the resin composition may contain other components such as reinforcing agents (also called fillers), softeners, antioxidants, ultraviolet absorbers, light stabilizers, pigments, surfactants, flame retardants, coupling agents, organic fillers, inorganic fillers, antiblocking agents, antistatic agents, colorants, inorganic antibacterial agents, organic antibacterial agents, lubricants, and silicone oils, to the extent that they do not impair the effects of the present invention, depending on the required properties for each application.

[0063] Examples of reinforcing agents include flexible olefin polymers such as ethylene-propylene copolymer rubber (EPM), ethylene-propylene-diene ternary copolymer rubber (EPDM), ethylene-butene copolymer rubber (EBM), amorphous poly-α-olefin (APAO), and ethylene-octene copolymer.

[0064] Examples of softening agents include paraffinic oils, naphthenic oils, and aromatic oils. Examples of antioxidants include hindered phenolic and hindered amine antioxidants. Examples of inorganic fillers include light calcium carbonate, heavy or calcium carbonate, other calcium-based fillers, hard clay, soft clay, kaolin clay, talc, wet silica, dry silica, amorphous silica, walnutite, synthetic zeolite, natural zeolite, diatomaceous earth, silica sand, pumice powder, slate powder, alumina, aluminum sulfate, barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, magnesium hydroxide, and silane-treated fillers. Suitable antiblocking agents include silica and zeolite, which can be natural or synthetic, and cross-linked spherical particles such as cross-linked acrylic spherical particles are also suitable. As antistatic agents, N,N-bis-(2-hydroxyethyl)-alkylamine compounds having an alkyl group with 12 to 18 carbon atoms and glycerin fatty acid esters are preferred. Furthermore, as lubricants, fatty acid amides are preferred, specifically including erucic acid amide, behenic acid amide, stearic acid amide, oleic acid amide, and the like.

[0065] (Method for manufacturing resin compositions) The method for producing the resin composition includes a step of heating and kneading components (A), (B), (C), and (D), or components (A), (B), (C), (D) and other components. The kneading is performed under heating conditions at a temperature of 160 to 200°C. If the temperature during kneading is below 160°C, components (A), (B), and (C) will not melt, making it difficult to uniformly mix each component, and the physical properties of the resulting resin composition, such as hardness, tensile properties, and compression set, will decrease. If the temperature during heating and kneading exceeds 200°C, the physical properties of the resulting resin composition will be inferior, in particular, the compression set will be large. The temperature during heating and kneading is preferably 170 to 200°C, more preferably 170 to 195°C, and even more preferably 170 to 190°C.

[0066] For the aforementioned mixing, batch-type mixing equipment or continuous-type mixing equipment can be used. Examples of batch-type mixing equipment include laboplast mills, brabenders, Banbury mixers, kneaders, and rolls. Examples of continuous-type mixing equipment include single-screw extruders and twin-screw extruders.

[0067] In the aforementioned kneading, the temperature is preferably 160 to 200°C, and more preferably 170 to 200°C. When using a batch-type kneading device, such as a laboplast mill, the kneading temperature is preferably 160 to 200°C, the kneading time is preferably 1 to 40 minutes, and the torque is preferably 10 to 20 N·m, more preferably the kneading temperature is 170 to 200°C, the kneading time is preferably 3 to 35 minutes, and the torque is preferably 15 to 20 N·m.

[0068] The aforementioned kneading may be carried out by putting all the components into a kneading device and heating and kneading until homogeneous. However, from the viewpoint of easily dispersing each component uniformly, it is preferable to pre-knead the components other than component (D), specifically the solid components, before adding the liquid component (D) and heating and kneading until homogeneous. In this case, the kneading process, including pre-kneading, is carried out under temperature conditions of 160 to 200°C.

[0069] If pre-mixing is included, the components other than component (D) can be pre-mixed at a temperature of 160-200°C for 1-5 minutes, then component (D) can be added and mixed at a temperature of 160-200°C for 1-40 minutes. More specifically, for example, when using a laboplast mill, the pre-mixing temperature is preferably 160-200°C, the time is 1-5 minutes, and the torque is 1-10 N·m; more preferably the pre-mixing temperature is 170-200°C, the time is 1-3 minutes, and the torque is 2-7 N·m; the mixing temperature after adding component (D) is preferably 160-200°C, the mixing time is 1-40 minutes, and the torque is 10-20 N·m; more preferably the mixing temperature is 170-200°C, the mixing time is 3-35 minutes, and the torque is 15-20 N·m.

[0070] The resin composition can be in the form of pellets, powder, sheets, etc., depending on the application. For example, it can be melt-kneaded in an extruder, extruded into strands, and then cut into cylindrical or rice-grain-shaped pellets using a cutter while being cooled in cold water.

[0071] From the viewpoint of deformation durability, the aforementioned resin composition preferably has a compression set of 55% or less, more preferably 50% or less, and even more preferably 45% or less, measured under conditions of 70°C, 22 hours, and a compressibility of 25% in accordance with JIS K 6262:2013. A lower compression set of the resin composition is preferable, but it may be, for example, 20% or more.

[0072] The hardness of the resin composition is preferably 10 to 95, more preferably 20 to 90, even more preferably 30 to 90, and particularly preferably 40 to 90, from the viewpoint of flexibility. In this specification, the hardness of the resin composition can be measured with a spring-type Type A durometer in accordance with JIS K 6253:2012.

[0073] The tensile breaking strength of the resin composition is preferably 6 to 30 MPa, more preferably 8 to 25 MPa, even more preferably 10 to 20 MPa, and particularly preferably 12 to 18 MPa, from the viewpoint of moldability. In this specification, the tensile breaking strength of the resin composition can be measured in accordance with JIS K 6251:2017.

[0074] The tensile elongation at break of the resin composition is preferably 500 to 750%, more preferably 530 to 720%, even more preferably 560 to 690%, and particularly preferably 590 to 660% from the viewpoint of moldability. In this specification, the tensile elongation at break of the resin composition can be measured in accordance with JIS K 6251:2017.

[0075] (Method of manufacturing a molded product) A molded article can be produced by appropriately molding the resin composition according to conventional methods. It can be molded using commonly used molding methods and apparatus, for example, by melt molding by extrusion molding, injection molding, press molding, blow molding, etc. Any molding machine capable of melting the molding material can be used as the molding apparatus. Examples include a kneader, extrusion molding machine, injection molding machine, press molding machine, blow molding machine, mixing roll, etc.

[0076] The molding temperature is preferably 150-250°C, more preferably 170-230°C, from the viewpoint of the appearance of the molded product. The molding pressure may be, for example, 1-10 MPa or 3-7 MPa.

[0077] The resin composition can be used in various molded articles that use general styrene-based thermoplastic elastomers, such as tubular molded articles, sealing molded articles, and sheet molded articles. However, due to its excellent moldability, compression set, and barrier properties, it is particularly suitable for use in tubular molded articles and sealing molded articles. Examples of tubular molded articles include medical tubes and industrial tubes. Examples of medical tubes include catheters, infusion tubes, peritoneal dialysis tubes, blood transfusion tubes, and blood circuit tubes (used in cardiopulmonary bypass machines and hemodialysis). Examples of industrial tubes include various tubes used to transport one or more substances selected from the group consisting of gases, liquids, and semi-solids, and specifically include food tubes and ink tubes. Examples of sealing molded articles include packing materials, sealing materials, gaskets, and stoppers, and specifically include drug stoppers, cap seals, fuel cell gaskets, secondary battery gaskets, solar cell sealing materials, and food liner materials. [Examples]

[0078] The present invention will be described in more detail below with reference to examples, but these examples do not limit the present invention in any way.

[0079] The measurement and evaluation methods used in the examples and comparative examples are as follows.

[0080] (Weight-average molecular weight and number-average molecular weight) The molecular weight was measured using gel permeation chromatography (GPC). Specifically, chloroform was used as the mobile phase, and the measurement was performed on a polystyrene gel column. The weight-average molecular weight and number-average molecular weight were determined in polystyrene equivalents. (Tensile breaking strength) Measurements were performed in accordance with JIS K 6251:2017. Test specimens were made from evaluation sheets pressed to a thickness of 2.0 mm, punched out in a No. 3 shape using a dumbbell. The tensile speed during measurement was 500 mm / min. (Tensile elongation at fracture) Measurements were performed in accordance with JIS K 6251:2017. Test specimens were made from evaluation sheets pressed to a thickness of 2.0 mm, punched out in a No. 3 shape using a dumbbell. The tensile speed during measurement was 500 mm / min. (hardness) Hardness was measured using a spring-type Type A durometer in accordance with JIS K 6253:2012. The hardness value was taken after 15 seconds. A 2.0 mm thick sheet was used as the test specimen. (Compression set) Measurements were taken in accordance with JIS K 6262:2013. A 12.0 mm thick sheet was used as the test specimen. Measurements were taken at 70°C for 22 hours with a 25% compression ratio.

[0081] The compounds used in the examples and comparative examples are as follows: (A) Components: Styrene-isobutylene-styrene block copolymer obtained in Production Example 1 below, styrene content 31% by weight, weight-average molecular weight 129,300, molecular weight distribution 1.26, hereinafter also referred to as SIBS. (B) Component: Hydrogenated styrene-butadiene-styrene block copolymer, Kraton Polymers Japan Co., Ltd. "Kraton G1633", hereafter also referred to as SEBS. (C) Ingredients: Random polypropylene, "Prime PolyPro F227D" manufactured by Prime Polymer Co., Ltd., hereinafter also referred to as PP. (D) Component: Polybutene oil, number average molecular weight 980, kinematic viscosity at 40°C 9,500 mmHg 2 / s, manufactured by ENEOS Corporation, "Nisseki Polybutene HV-100", hereinafter also referred to as PB. Antioxidant: Hindered phenol antioxidant, "AO-50" manufactured by ADEKA Corporation, hereinafter also referred to as "AO-50".

[0082] (Manufacturing Example 1) <Synthesis of styrene-isobutylene-styrene block copolymer> A 1 L separable flask was used as the polymerization vessel. After purging the inside of the polymerization vessel with nitrogen, 500 mL of a mixed organic solvent, consisting of butyl chloride and n-hexane in a volume ratio of 9:1, was added to the polymerization vessel using a syringe. Next, the polymerization vessel was cooled by immersing it in dry ice / echina at -70°C, and then 126 mL (1.33 mol) of isobutylene was added. Next, 0.130 mL (1.33 mmol) of 2-methylpyridine was added. Then, 1.73 g of a 15 wt% p-dicumyl chloride solution (p-dicumyl chloride: 1.12 mmol) and 8.0 mL of a mixed organic solvent, consisting of butyl chloride and n-hexane in a volume ratio of 9:1, were added. Next, after confirming that the solution in the polymerization vessel had cooled to -70°C, the polymerization reaction was initiated by adding 1.53 mL (13.9 mmol) of titanium(IV) chloride. During the reaction, the polymerization solution was withdrawn periodically, and the consumption rate of isobutylene was measured by gas chromatography. Sixty minutes after the addition of titanium(IV) chloride, it was confirmed that 99.9 mol% of the isobutylene had been consumed. Seventy-seven minutes after the addition of titanium(IV) chloride, 39.9 mL (0.347 mol) of styrene was added. Fifty-eight minutes after the addition of styrene, it was confirmed by gas chromatography that 92 mol% of the added styrene had been consumed. Next, the entire polymerization solution was poured into a mixture of 320 mL of pure water heated to 50°C and 150 g of a mixed organic solvent consisting of butyl chloride and n-hexane in a volume ratio of 9:1. After the internal temperature of the reaction mixture reached 50°C, polymerization was stopped by vigorous stirring for 60 minutes. The organic phase and the aqueous phase were separated, and the separated aqueous phase was drained. Next, 277 mL of pure water was added to the organic phase, and the organic phase was washed by vigorously stirring at 50°C for 30 minutes. The organic phase and the aqueous phase were separated, and the separated aqueous phase was drained off. The same washing procedure was repeated one more time. After that, volatile components such as water and organic solvents were removed from the organic phase under heating, and the mixture was dried to obtain styrene-isobutylene-styrene block copolymer (SIBS). The obtained SIBS had a weight-average molecular weight of 129,300, a molecular weight distribution of 1.26, and a styrene-based polymer block content of 31% by weight.

[0083] (Example 1) <Preparation of resin composition> 12.0g of SIBS, 16.0g of SEBS, and 2.0g of PP were weighed out and melt-kneaded (pre-kneaded) for 1 minute using a Laboplast Mill (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number "4C150") set to 180℃ and 50rpm. Then, 10.0g of PB was added and melt-kneaded for another 5 minutes, after which the resin composition was removed. During the pre-kneading, the indicated torque of the Laboplast Mill was 2.9 N·m. The time during which melt-mixing continued after adding PB was defined as the mixing time below. During the mixing time, the indicated temperature of the laboplast mill was 180-187°C, and the indicated torque was 16.6-17.1 N·m. <Fabrication of Molded Body 1> The resin composition obtained above was heated and pressed in a press machine (manufactured by Shinto Metal Industries Co., Ltd., model number "NSF-50") preheated to 180°C under a pressure of 5 MPa to obtain a sheet with a thickness of 2.0 mm. <Fabrication of Molded Body 2> The resin composition obtained above was heated and pressed in a press machine (manufactured by Shinto Metal Industries Co., Ltd., model number "NSF-50") preheated to 180°C under a pressure of 5 MPa to obtain a sheet with a thickness of 12.0 mm.

[0084] (Example 2) A resin composition, molded body 1, and molded body 2 were obtained in the same manner as in Example 1, except that the kneading time was set to 15 minutes. During the kneading time, the indicated temperature of the laboplast mill was 173 to 186°C, and the indicated torque was 17.6 to 18.6 N·m.

[0085] (Example 3) 12.0g of SIBS, 16.0g of SEBS, 2.0g of PP, and 0.06g of AO-50 were weighed out and melt-kneaded (pre-kneaded) for 1 minute using a Laboplast Mill (manufactured by Toyo Seiki Seisakusho) set to 180℃ and 50rpm. Then, 10.0g of PB was added and kneaded for 30 minutes, after which the resin composition was removed. During pre-kneading, the indicated torque of the Laboplast Mill was 3.1 N·m. During the kneading time, the indicated temperature of the Laboplast Mill was 186~187℃ and the indicated torque was 18.3~18.8 N·m. Using the obtained resin composition, molded articles 1 and 2 were produced in the same manner as in Example 1.

[0086] (Comparative Example 1) A resin composition, molded body 1, and molded body 2 were obtained in the same manner as in Example 3, except that the amount of AO-50 added was 0.24 g and the setting temperature of the Laboplastmill was 210°C. During the mixing time, the indicated temperature of the Laboplastmill was 211 to 214°C and the indicated torque was 8.9 to 15.5 N·m.

[0087] (Comparative Example 2) A resin composition, molded body 1, and molded body 2 were obtained in the same manner as in Example 3, except that the Laboplastmill was set to a temperature of 210°C and the kneading time was 5 minutes. During the kneading time, the Laboplastmill's indicated temperature was 212-213°C and the indicated torque was 10.3-14.1 N·m.

[0088] The tensile strength, elongation at break, hardness, and compression set of the resin compositions obtained in the examples and comparative examples were measured as described above, and the results are shown in Table 1 below. The mixing ratios of each component and the mixing conditions are also shown in Table 1 below.

[0089] [Table 1]

[0090] From the above results, it can be seen that the resin compositions obtained in Examples 1 to 3, in which components (A), (B), (C), and (D) were melt-kneaded at a temperature of 200°C or lower, were superior in tensile properties and compression set to the resin compositions obtained in Comparative Examples 1 and 2, in which components were melt-kneaded at a temperature exceeding 200°C.

Claims

1. (A) Components: 100 parts by weight of a block copolymer consisting of a styrene polymer block and an isobutylene polymer block, (B) Component: 100 to 250 parts by weight of a styrene-based thermoplastic elastomer other than component A, (C) Components: 1 to 50 parts by weight of polypropylene, and (D) Components: Includes a step of kneading 30 to 200 parts by weight of polybutene oil, The aforementioned polypropylene is random polypropylene, The kneading is performed at 160 to 200°C, in a method for producing a resin composition.

2. A method for producing the resin composition according to claim 1, wherein the weight-average molecular weight of component (A) is 50,000 to 200,000.

3. A method for producing the resin composition according to claim 1 or 2, wherein in component (A), the ratio of styrene polymer blocks to isobutylene polymer blocks is 10:90 to 50:50 by weight.

4. A method for producing the resin composition according to any one of claims 1 to 3, wherein component (B) is a hydrogenated styrene-based thermoplastic elastomer.

5. The method for producing a resin composition according to any one of claims 1 to 4, wherein the kneading is performed for 1 to 40 minutes.

6. The method for producing a resin composition according to any one of claims 1 to 5, wherein the kneading is performed under conditions of a torque of 10 to 20 N·m.

7. The method for producing a resin composition according to any one of claims 1 to 6, wherein the kneading is carried out for 3 to 35 minutes under conditions of a temperature of 170 to 200°C and a torque of 15 to 20 N·m.

8. A step of producing a resin composition using the method for producing a resin composition described in any one of claims 1 to 7, and A method for manufacturing a resin molded article, comprising the step of molding the aforementioned resin composition.

9. The method for manufacturing a resin molded article according to claim 8, wherein the resin molded article is one or more selected from the group consisting of medical tubes, food tubes, ink tubes, drug stoppers, cap seals, fuel cell gaskets, and secondary battery gaskets.

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