Resin sheet for packaging electronic components and electronic component packaging container using the same

Abstract

[Problem] To provide: a resin sheet which is for packaging an electronic component and has transparency, excellent folding endurance, and excellent low-temperature heat sealability; and an electronic component packaging container using the same. [Solution] This resin sheet for packaging an electronic component is composed of a rubber-modified aromatic vinyl copolymer resin containing a rubbery polymer (Y) as a dispersed particle in a continuous matrix resin (X) and satisfying the following (1)-(2). (1) The continuous matrix resin (X) is a copolymer of 53-63 mass% of at least one aromatic vinyl compound (x1) and 37-47 mass% of at least one alkyl (meth)acrylate (x2). (2) The proportion of the rubbery polymer (Y) is 5-10 mass% (exclusive of 10) with respect to the total mass of the rubber-modified aromatic vinyl copolymer resin.

Description

[Technical Field]

[0001] The present invention relates to a resin sheet for packaging electronic components and a container for packaging electronic components using the same. [Background technology]

[0002] Rigid polyvinyl chloride (PVC) has traditionally been used in packaging containers for electronic components, such as IC magazines and IC carrier tapes, due to its excellent physical properties, including transparency, impact resistance, rigidity, and surface hardness. However, PVC alternatives are needed due to concerns about the release of acidic, corrosive gases and toxic substances during waste incineration. As an alternative material that addresses these drawbacks, a blend resin composed of at least one resin selected from polystyrene and a styrene-(meth)acrylic acid ester copolymer with a styrene-butadiene block copolymer is known (see, for example, Patent Document 1). However, this blend resin is difficult to achieve both the rigidity and impact resistance required for packaging containers for electronic components. In other words, this blend resin has a trade-off relationship in which increasing rigidity decreases impact resistance, and vice versa. Therefore, it is difficult to say that it is a well-balanced material that can simultaneously achieve the rigidity and impact resistance required for packaging containers for electronic components. Other PVC alternatives, such as polycarbonate resin and transparent ABS resin, are known, but they are expensive and lack practicality as low-cost PVC alternatives.

[0003] Patent Document 2 proposes a rubber-modified styrene-based resin composition that can be used to obtain transparent molded articles for packaging electronic components, which have high strength, excellent transparency and rigidity, and high surface hardness. Patent Document 2 also describes a transparent molded article for packaging electronic components formed from a rubber-modified styrene-based resin composition that includes a rubber-modified styrene-based resin obtained by polymerizing a mixed solution of styrene, a (meth)acrylic acid alkyl ester, and a butadiene-based rubber polymer, and a terpene-based resin or a hydrogenated terpene-based resin. However, molded articles formed from such rubber-modified styrene-based resin compositions are insufficient in physical properties such as strength and transparency, and in surface hardness.

[0004] In contrast, Patent Document 3 proposes a rubber-modified aromatic vinyl copolymer resin that can produce molded articles for packaging electronic components that have excellent physical properties such as strength and transparency and sufficiently high surface hardness. Patent Document 3 describes that transparent molded articles for packaging electronic components that have high strength, excellent transparency and rigidity, and also high surface hardness can be produced by extruding a resin composition in which a styrene-butadiene block copolymer of a specific structure that can be graft-copolymerized with a mixture of an aromatic vinyl compound and a (meth)acrylic acid alkyl ester compound and that has a particularly strong affinity with the mixture is dispersed as a rubber-like polymer in the mixture. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-12847 [Patent Document 2] Japanese Patent Application Publication No. 9-301479 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-193378 Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, in view of the need for high-speed filling of electronic components, packaging containers for electronic components are also required to have low-temperature heat sealability that allows high peel strength to be obtained in a short sealing time. Furthermore, there is also a need for a balance between physical properties such as folding strength and moldability while maintaining high transparency that allows the electronic components contained therein to be visually observed from the outside. Therefore, an object of the present invention is to provide a resin sheet for packaging electronic components that has transparency, excellent folding strength, and excellent low-temperature heat sealing properties, and an electronic component packaging container made using the same. [Means for solving the problem]

[0007] As a result of intensive research into the above-mentioned problems, the present inventors have surprisingly found that a resin sheet made of a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer as dispersed particles in a continuous matrix resin obtained by copolymerizing an aromatic vinyl compound with a (meth)acrylic acid alkyl ester, wherein the aromatic vinyl compound is copolymerized in an amount of 53 to 63 mass % and the (meth)acrylic acid alkyl ester is copolymerized in an amount of 37 to 47 mass % and the rubber-like polymer accounts for 5 mass % or more and less than 10 mass % of the total mass of the rubber-modified aromatic vinyl copolymer resin, can be obtained, which has excellent transparency, impact resistance, and rigidity, as well as excellent low-temperature heat sealing properties, and has thereby completed the present invention. That is, the present invention has the following aspects. [1] A resin sheet for packaging electronic components, which is composed of a rubber-modified aromatic vinyl copolymer resin containing a continuous matrix resin (X) and a rubber-like polymer (Y) as dispersed particles, and which satisfies the following (1) and (2): (1) The continuous matrix resin (X) is a copolymer of 53 to 63 mass % of one or more aromatic vinyl compounds (x1) and 37 to 47 mass % of one or more (meth)acrylic acid alkyl esters (x2), (2) The proportion of the rubber-like polymer (Y) relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 5% by mass or more and less than 10% by mass. [2] The resin sheet for packaging electronic components according to [1], wherein the (meth)acrylic acid alkyl ester (x2) comprises methyl methacrylate (x2-1) and a (meth)acrylic acid alkyl ester (x2-2) having a linear or branched alkyl group having 4 to 8 carbon atoms. [3] The resin sheet for packaging electronic components according to [2], wherein the proportion of the (meth)acrylic acid alkyl ester (x2-2) relative to the total mass of the (meth)acrylic acid alkyl ester (x2) is 5 to 50 mass %. [4] The resin sheet for packaging electronic components according to [2] or [3], wherein the (meth)acrylic acid alkyl ester (x2-2) contains butyl acrylate. [5] An electronic component packaging container made using the resin sheet for packaging electronic components according to any one of [1] to [4]. [6] The electronic component packaging container according to [5], which is a carrier tape. [7] The electronic component packaging container according to [5], which is a tray. [8] An electronic component packaging body comprising the electronic component packaging container according to any one of [5] to [7]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin sheet for packaging electronic components that has transparency, excellent folding strength, and excellent low-temperature heat sealing properties, and an electronic component packaging container made using the same. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below, but the present invention is not limited to the following embodiments. In this specification, the symbol "to" means "not less than" or "not more than." For example, "5 to 10% by mass" means "not less than 5% by mass and not more than 10% by mass." [Resin sheets for packaging electronic components] The resin sheet for packaging electronic components according to the present invention (hereinafter sometimes simply referred to as "resin sheet") contains a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X), and is composed of a rubber-modified aromatic vinyl copolymer resin that satisfies the following (1) and (2): (1) The continuous matrix resin (X) is a copolymer of 53 to 63 mass % of one or more aromatic vinyl compounds (x1) and 37 to 47 mass % of one or more (meth)acrylic acid alkyl esters (x2), (2) The proportion of the rubber-like polymer (Y) relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 5% by mass or more and less than 10% by mass. The resin sheet for packaging electronic components according to the present invention, which is made from a rubber-modified aromatic vinyl copolymer resin having such a characteristic composition, has transparency, excellent folding strength, and excellent low-temperature heat sealing properties.

[0010] <Rubber-modified aromatic vinyl copolymer resin> The rubber-modified aromatic vinyl copolymer resin according to the present invention (hereinafter simply referred to as "copolymer resin") contains a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X), and is characterized by satisfying the following (1) and (2): (1) The continuous matrix resin (X) is a copolymer of 53 to 63 mass % of one or more aromatic vinyl compounds (x1) and 37 to 47 mass % of one or more (meth)acrylic acid alkyl esters (x2), (2) The proportion of the rubber-like polymer (Y) relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 5% by mass or more and less than 10% by mass. By satisfying the above (1) and (2), a resin sheet having excellent low-temperature heat sealing property, transparency, and folding strength can be obtained.

[0011] (Continuous matrix resin (X)) The continuous matrix resin (X) is a resin component that forms a continuous phase in the copolymer resin. The continuous matrix resin (X) is a copolymer of one or more aromatic vinyl compounds (x1) (hereinafter sometimes referred to as "component (x1)") and one or more (meth)acrylic acid alkyl esters (x2) (hereinafter sometimes referred to as "component (x2)"). Specifically, the continuous matrix resin (X) is obtained by copolymerizing 53 to 63 mass % of the component (x1) and 37 to 47 mass % of the component (x2) relative to the total mass of the continuous matrix resin (X).

[0012] (Aromatic vinyl compound (x1)) Examples of the aromatic vinyl compound (x1) include styrene; α-alkyl-substituted styrenes such as α-methylstyrene and α-methyl-p-methylstyrene; nuclear alkyl-substituted styrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, and p-tert-butylstyrene; nuclear halogenated styrenes such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, 2-methyl-1,4-chlorostyrene, and 2,4-dibromostyrene; and vinylnaphthalene, among others. These styrene compounds can be used alone or in combination of two or more, and are conventionally used in rubber-modified styrene resins. Among these, styrene is preferably used.

[0013] The proportion of the (x1) component in the continuous matrix resin (X) is 53 to 63 mass%, preferably 53.5 to 62.5 mass%, more preferably 54 to 61 mass%, and particularly preferably 54 to 60 mass%, relative to the total mass of the continuous matrix resin (X). By controlling the proportion of the (x1) component within the above range, the proportion of the (x2) component in the continuous matrix resin (X) can be adjusted to 37 to 47 mass%, resulting in a resin sheet with excellent low-temperature heat-sealing properties. A particularly preferred copolymer resin contains 53 to 63 mass%, preferably 53.5 to 62.5 mass%, of styrene as (x1), relative to the total mass of the continuous matrix resin (X). The proportion of the (x1) component in the (X) component refers to the proportion of the (x1) component relative to the total amount (100 mass%) of all monomers constituting the (X) component. A proportion of the (x1) component of 53 to 63 mass% can be achieved, for example, by adjusting the monomer charging ratio. The same applies to the ratio of the (x2) component in the (X) component, which will be described later.

[0014] The proportion of the (x1) component in the copolymer resin is preferably 48.0 to 57.0 mass%, more preferably 49.5 to 55.0 mass%, and particularly preferably 50.5 to 54.0 mass%, relative to the total mass of the copolymer resin. When the proportion of the (x1) component in the copolymer resin is within the above range, a resin sheet with excellent low-temperature heat-sealability is more easily obtained. The proportion of the (x1) component in the copolymer resin is a value calculated from the following formula (1): [(x1) / (X+Y)]×100 (1) In formula (1), x1 is the total amount of all monomers used to make up the component (x1), X is the value obtained by multiplying the total amount of all monomers used to make up the component (X) by the polymerization rate (%), and Y is the total amount of rubber-like polymers used to make up the component (Y).

[0015] ((Meth)acrylic acid alkyl ester (x2)) In the copolymer resin according to the present invention, the (meth)acrylic acid alkyl ester means a methacrylic acid alkyl ester and an acrylic acid alkyl ester. Examples of the component (x2) include (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 18 carbon atoms. Specific examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, tridecyl methacrylate, palmitic methacrylate, pentadecyl methacrylate, stearyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, lauryl acrylate, tridecyl acrylate, palmitic acrylate, pentadecyl acrylate, and stearyl acrylate. These may be used alone or in combination of two or more.

[0016] The proportion of component (x2) in the continuous matrix resin (X) is 37 to 47 mass%, preferably 37.5 to 46.5 mass%, more preferably 39 to 46 mass%, and particularly preferably 40 to 45 mass%, based on the total mass of the continuous matrix resin (X). By keeping the proportion of component (x2) within this range, the proportion of component (x1) in the continuous matrix resin (X) can be adjusted to 53 to 63 mass%, resulting in a resin sheet with excellent low-temperature heat-sealing properties.

[0017] The proportion of the (x2) component in the copolymer resin is preferably 33 to 44 mass% and more preferably 35 to 44 mass% relative to the total mass of the copolymer resin. By setting the proportion of the (x2) component in the copolymer resin within this range, a resin sheet with excellent heat-sealability at lower temperatures can be more easily obtained. Note that when the (x2) component contains methyl methacrylate and butyl acrylate, as described below, the proportion of the (x2) component in the copolymer resin may be in the range of 37 to 43 mass% relative to the total mass of the copolymer resin. The proportion of the (x2) component in the copolymer resin is calculated from the following formula (2). [(x2) / (X+Y)]×100 (2) In formula (2), x2 is the total amount of all monomers used to make up the component (x2), X is the value obtained by multiplying the total amount of all monomers used to make up the component (X) by the polymerization rate (%), and Y is the total amount of all rubber-like polymers used to make up the component (Y).

[0018] Of the aforementioned (meth)acrylic acid alkyl esters, the (x2) component preferably contains methyl methacrylate (x2-1) (hereinafter also referred to as "(x2-1) component") and a (meth)acrylic acid alkyl ester (x2-2) having a linear or branched alkyl group having 4 to 8 carbon atoms (hereinafter also referred to as "(x2-2) component"). Examples of the component (x2-2) include butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate. Among (meth)acrylic acid alkyl esters, methyl methacrylate (MMA) and (meth)acrylic acid alkyl esters having an alkyl group with 4 to 8 carbon atoms tend to have low Tg. By combining (meth)acrylic acid alkyl ester monomers with low Tg in this way, the resin becomes more likely to soften even at low temperatures, making it easier to obtain a resin sheet with excellent heat-sealing properties at low temperatures.

[0019] The (x2-2) component is preferably an alkyl acrylate having a linear or branched alkyl group having 4 to 8 carbon atoms, more preferably butyl acrylate or 2-ethylhexyl acrylate, and particularly preferably butyl acrylate. The (x2) component is most preferably a mixture of the (x2-1) component and butyl acrylate. By combining the (x2-1) component with butyl acrylate, the Tg of the continuous matrix resin (X) is lowered, improving low-temperature heat sealing properties, while also preventing a decrease in transparency, folding strength, etc.

[0020] The proportion of the (x2-2) component in the (x2) component is preferably 5 to 50 mass%, more preferably 10 to 40 mass%, even more preferably 10 to 30 mass%, and particularly preferably 10 to 20 mass%, relative to the total mass of the (x2) component. When the proportion of the (x2-2) component in the (x2) component is within the above range, good heat sealability at low temperatures is likely to be achieved, and a good balance of transparency, folding strength, and the like is also likely to be achieved. From the viewpoint of good heat sealability at lower temperatures, the proportion of the (x2-2) component may be in the range of 13 to 18 mass%, relative to the total mass of the (x2) component. In this specification, the proportion of the (x2-2) component in the (x2) component means the proportion of the (x2-2) component relative to the total amount (100% by mass) of the (meth)acrylic acid alkyl esters constituting the (x2) component.

[0021] In one embodiment, when the component (x2) is a mixture of the components (x2-1) and (x2-2), and the component (x2-2) is butyl acrylate, the ratio of MMA to butyl acrylate (MMA / butyl acrylate) is preferably 1 to 7, more preferably 3 to 7, and particularly preferably 4 to 6, from the viewpoint of improving heat sealability at lower temperatures. By setting the ratio of MMA to butyl acrylate within the above range, it becomes easier to maintain a lower Tg of the resin sheet while also achieving sheet strength. This makes it easier to obtain a resin sheet that achieves both low-temperature heat sealability and physical properties such as folding endurance.

[0022] The continuous matrix resin (X) may contain a monomer (other monomer) other than the component (x1) and the component (x2). The other monomer is a compound copolymerizable with the component (x1) and the component (x2). Examples of the other monomer include vinyl cyanides such as acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, and α-chloroacrylonitrile; methacrylic acid; acrylic acid; maleimides such as maleic anhydride and phenylmaleimide; vinyl acetate; and divinylbenzene. These may be used alone or in combination of two or more. From the viewpoint of maintaining a balance of various physical properties such as image clarity and folding strength and easily obtaining a resin sheet that also has excellent low-temperature heat-sealing properties, it is particularly preferred that the continuous matrix resin (X) be composed only of the component (x1) and the component (x2).

[0023] (Rubber polymer (Y)) The copolymer resin according to the present invention contains the rubbery polymer (Y) in an amount of 5% by mass or more and less than 10% by mass based on the total mass of the copolymer resin. Packaging containers for electronic components require high transparency that allows the enclosed electronic components to be visually recognized from the outside. In conventional resin sheets made from rubber-modified aromatic vinyl copolymer resins, it is difficult to reduce the amount of rubber component from the standpoint of sheet strength (impact resistance and rigidity), and a rubber component of approximately 12% by mass is required. Therefore, it is difficult to obtain a resin sheet that achieves both high transparency (image clarity) and high sheet strength by reducing the amount of rubber component. The present inventors have discovered that by controlling the blending ratios of the (x1) and (x2) components constituting the continuous matrix resin (X) within a certain range, a resin sheet with sufficient sheet strength can be easily obtained even with a reduced blending amount of the rubber-like polymer (Y). Furthermore, surprisingly, they have also discovered that combining the (x1) and (x2) components within the aforementioned specific range facilitates resin softening, making it easier to obtain a resin sheet with excellent heat-sealability at lower temperatures. As described above, the copolymer resin according to the present invention has good transparency because the proportion of the rubber-like polymer (Y) is 5% by mass or more but less than 10% by mass. The rubbery polymer (Y) is preferably a copolymer of styrene and butadiene. The proportion of the rubbery polymer (Y) in the copolymer resin is preferably 5 to 9 mass %, more preferably 5.5 to 8.5 mass %, and particularly preferably 5.5 to 8.0 mass %, based on the total mass of the copolymer resin. The amount of the rubber-like polymer (Y) in the copolymer resin can also be calculated from the following formula (3). [(Y) / (X+Y)]×100 (3) In formula (3), Y is the total amount of all rubber-like polymers (Y) charged, and X is the value obtained by multiplying the total amount of all monomers constituting component (X) charged by the polymerization rate (%).

[0024] The rubbery polymer (Y) contained in the copolymer resin according to the present invention is preferably a styrene-butadiene copolymer (SBR). The styrene concentration in the SBR is preferably 10 to 50 mass%, more preferably 10 to 45 mass%, and even more preferably 15 to 40 mass%, relative to the total mass of the SBR. When the styrene concentration is within the above range, the difference in refractive index between the matrix resin (X) and the rubbery polymer (Y) becomes small, and transparency tends to be good.

[0025] <Method of producing rubber-modified aromatic vinyl copolymer resin> The copolymer resin according to the present invention can be obtained by, for example, polymerizing a raw material mixture containing the (x1) component and the (x2) component in the presence of the rubbery polymer (Y), thereby obtaining a copolymer resin containing the rubbery polymer (Y) as dispersed particles in the continuous matrix resin (X). The ratio of the (x1) component to the (x2) component in the raw material mixture can be adjusted so that the (x1) component in the continuous matrix resin (X) is 53 to 63 mass % and the (x2) component is 37 to 47 mass %.

[0026] The rubbery polymer (Y) may be a commercially available product or may be produced by living anionic polymerization or the like. As a commercially available product, for example, "Asaprene (registered trademark)" manufactured by Asahi Kasei Corporation can be used. When producing the rubbery polymer (Y), for example, a method of living anionic polymerization of a monomer mixture containing styrene and butadiene in a hydrocarbon solvent in the presence of an organolithium catalyst can be used. Specifically, the method described in JP-A-2002-193378 can be used.

[0027] The raw material mixture may contain an organic solvent, if necessary. Examples of organic solvents include benzene, toluene, xylene, ethylbenzene, acetone, isopropylbenzene, methyl ethyl ketone, methyl isobutyl ketone, and dimethylformamide. These may be used alone or in combination of two or more. Among these, toluene and ethylbenzene are preferred. Use of an organic solvent makes it easier to control the monomer concentration and polymer concentration in the polymerization liquid, and therefore the polymerization reaction. When an organic solvent is used, it can be used in an amount of 5 to 50 parts by mass relative to the total amount (100 parts by mass) of the raw material mixture used to produce the copolymer resin. More preferably, it is used in an amount of 5 to 10 parts by mass. Furthermore, other solvents, such as aliphatic hydrocarbons and dialkyl ketones, can be used in combination with aromatic hydrocarbons, so long as the solubility of the rubbery polymer (Y) is not impaired.

[0028] The raw material mixture may contain a polymerization initiator, and an organic peroxide is preferably used as the polymerization initiator. Examples of organic peroxides include peroxyketals such as 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, and n-butyl-4,4-bis(t-butylperoxy)valerate; di-t-butyl peroxide, t-butylcumyl peroxide, di-cumyl peroxide, α,α'-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t- Dialkyl peroxides such as 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3; diacyl peroxides such as acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-toluoyl peroxide; diisopropyl peroxide peroxycarbonates such as dicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-methoxyisopropyl peroxydicarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate; t-butyl peroxyacetate, t-butyl peroxyiso peroxyesters such as butyrate, t-butyl peroxypiparate, t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, di-t-butyl diperoxyisophthalate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and t-butyl peroxyisopropyl carbonate;Examples of suitable organic peroxides include ketone peroxides such as acetylacetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide; and polyacyl peroxides of dibasic acids and polyperoxy esters of dibasic acids and polyols. These organic peroxides may be used alone or in combination as a polymerization initiator. The amount of the organic peroxide is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 0.001 to 5.0 parts by mass per 100 parts by mass of the total amount of the raw material mixture.

[0029] In addition, a chain transfer agent, an antioxidant, etc. may be added during the polymerization. Examples of chain transfer agents include mercaptans, α-methylstyrene linear dimer, monoterpenoid molecular weight modifiers (turbinolenes), etc. These may be used alone or in combination of two or more. Examples of antioxidants include hindered phenols, hindered bisphenols, hindered trisphenols, etc. Specifically, for example, 2,6-di-t-butyl-4-methylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, etc. may be used.

[0030] The copolymer resin according to the present invention may contain additives such as antioxidants, inorganic stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, and organic polysiloxanes, as required. Antioxidants include the same antioxidants as those mentioned above. Examples of inorganic stabilizers include calcium and tin. Examples of ultraviolet absorbers include p-tert-butylphenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenophen, and 2-(2'-hydroxy-4'-n-octoxyphenyl)benzothiazole. Examples of flame retardants include antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, chlorinated paraffin, tetrabromobutane, hexabromobutane, tetrabromobisphenol A, and the like. Examples of the antistatic agent include stearamidopropyl dimethyl-β-hydroxyethyl ammonium nitrate. Examples of colorants include titanium oxide, carbon black, and other inorganic or organic pigments. Examples of fillers include calcium carbonate, clay, silica, glass fiber, glass spheres, carbon fiber, and reinforcing elastomers such as methyl methacrylate-butadiene-styrene copolymer (MBS), styrene-butadiene-styrene copolymer (SBS), styrene-isoprene copolymer (SIS), or hydrogenated products thereof. The additives may be used alone or in combination of two or more, and may be added during production.

[0031] The copolymer resin according to the present invention may contain a plasticizer and a lubricant, if necessary. The plasticizer may be any known plasticizer, and examples thereof include phthalic acid-based plasticizers such as dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, butyl benzyl phthalate, and butyl phthalyl butyl glycolate; adipic acid-based plasticizers such as di-n-butyl adipate and di-(2-ethylhexyl adipate); citric acid-based plasticizers such as acetyl tri-n-butyl citrate; sebacic acid-based plasticizers such as di-n-butyl sebacate and di-(2-ethylhexyl) sebacate; epoxy-based plasticizers such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized fatty acid esters; polyester-based plasticizers composed of dibasic acids such as succinic acid, glutaric acid, and adipic acid and dihydric alcohols having a molecular weight of 200 or less, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol; terpene-based resins; and hydrogenated terpene-based resins. These plasticizers may be used alone or in combination of two or more. The copolymer resin according to the present invention may also contain a (meth)acrylic acid alkyl ester (x2) monomer. By including the (x2) monomer as a plasticizer, the resin sheet according to the present invention is more likely to soften, and the heat sealability at low temperatures is more likely to be improved. The monomer may be added to the copolymer resin, or may be a residual monomer present during production. When the copolymer resin contains the (x2) monomer, its proportion relative to the total mass of the copolymer resin is preferably 700 ppm or less, more preferably 10 to 500 ppm, and even more preferably 20 to 300 ppm. When the monomer is a residual monomer present during production, the proportion of the residual monomer in the copolymer resin may be controlled within the above-mentioned range by adjusting the polymerization temperature, polymerization time, etc.

[0032] Conventional lubricants can be used, including metal soap-based lubricants, hydrocarbon-based liquid paraffin, polyethylene wax, etc., fatty acid-based higher fatty acids, oxyfatty acids, etc., ester-based glycerides, ester wax, etc., fatty acid amide-based fatty acid amides, bisfatty acid amides, etc., fatty acid ketone-based lubricants, and composite lubricants. Specific examples include paraffin wax, stearic acid, hydrogenated oil, stearamide, ethylene bisstearylamide, n-butyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride, polysiloxane, and alkyl phosphate ester. These lubricants may be used alone or in combination of two or more.

[0033] When a plasticizer or lubricant is contained, the amount added is preferably within a range of 0.05 to 1.0 parts by mass relative to the total mass of the copolymer resin, from the viewpoint of the processability of the resin sheet and the sealing properties of the packaging container.

[0034] [Manufacturing method of resin sheet] The resin sheet according to the present invention is made of the copolymer resin described above. Conventional known methods can be used to manufacture the resin sheet. Specifically, the copolymer resin is fed into an extruder and melt-kneaded to produce resin pellets. These resin pellets are then fed into a sheet extruder such as a T-die and extruded to a desired thickness to form a resin sheet. A conductive layer can also be formed on at least one surface of the resin sheet to produce a conductive resin sheet.

[0035] The thickness of the resin sheet according to the present invention is preferably 0.1 to 1 mm, more preferably 0.15 to 0.8 mm, from the viewpoint of formability and strength of the packaging container.

[0036] <Bending strength> The resin sheet according to the present invention has excellent folding endurance. That is, the folding endurance of the resin sheet according to the present invention, measured according to JIS-P-8115, is preferably 10 times or more, more preferably 30 times or more, and even more preferably 50 times or more. The folding endurance of the resin sheet refers to a value measured under the following conditions. (Method for measuring folding endurance) According to JIS-P-8115 (2001), a test piece 150 mm long, 15 mm wide, and 0.3 mm thick is prepared with the machine direction of the resin sheet as the length direction. The MIT folding endurance is measured using an MIT folding fatigue tester manufactured by Toyo Seiki Seisakusho Co., Ltd. The test is performed at a folding angle of 135 degrees, a folding speed of 175 times / min, and a measuring load of 250 g.

[0037] <Image clarity> The image clarity of the resin sheet according to the present invention, as measured with an image clarity measuring device in accordance with JIS-K-7324, is preferably 60% or more, more preferably 70% or more, and even more preferably 75% or more. An image clarity of 60% or more makes it easier to visually recognize electronic components stored in pockets of an electronic component packaging container. In other words, a resin sheet having such image clarity has excellent transparency.

[0038] [Electronic component packaging containers] By molding the resin sheet according to the present invention by a known sheet molding method (thermoforming) such as vacuum molding, pressure molding, press molding, etc., it is possible to obtain electronic component packaging containers of any shape, such as carrier tapes, trays, etc. The resin sheet according to the present invention has transparency, excellent folding strength, and excellent low-temperature heat sealing properties, and therefore it is possible to provide electronic component packaging containers that are excellent in these physical properties.

[0039] <Low temperature heat sealability> The electronic component packaging container according to the present invention has excellent low-temperature heat-sealing properties. Specifically, the sealing temperature at which the peel strength of the cover tape measured under the following conditions is 0.2 N or more is preferably lower than 165°C, more preferably 155°C or lower, and even more preferably 145°C or lower. (Method for measuring low-temperature heat sealability) Using a taping machine, heat-seal a 21.5mm wide cover tape to the carrier tape using a seal head width of 0.5mm x 2, a seal head length of 24mm, a seal pressure of 0.5kgf, a feed length of 12mm, a seal time of 0.3 seconds, and a seal iron temperature of 140-190°C in 5°C intervals. Then, in an atmosphere of 23°C and 50% relative humidity, peel the cover tape at a peel angle of 170°-180° at a peel speed of 300mm per minute, and confirm the sealing temperature at which the peel strength is 0.2N or more.

[0040] [Electronic component packaging] The electronic component packaging container is used to store and transport electronic components by storing electronic components in the electronic component packaging container. For example, a carrier tape is used to store and transport electronic components by storing electronic components in pockets formed by the molding method, covering the pockets with a cover tape, and then winding the carrier tape into a reel. The resin sheet and electronic component packaging container according to the present invention have excellent heat-sealing properties at low temperatures. Therefore, the heat-sealing temperature when forming the electronic component packaging body is preferably less than 165°C, more preferably 155°C or less, and even more preferably 145°C or less. Another aspect of the present invention is a method for producing an electronic component packaging body using an electronic component packaging container made of a resin sheet constituted by the copolymer resin, the method comprising heat-sealing a lid material to the electronic component packaging container at a heat-sealing temperature of less than 165°C, preferably 155°C or less.

[0041] There are no particular limitations on the electronic components that can be packaged in the electronic component packaging, and examples include ICs, LEDs (light-emitting diodes), resistors, liquid crystals, capacitors, transistors, piezoelectric element resistors, filters, crystal oscillators, diodes, connectors, switches, volumes, relays, inductors, etc. The electronic components may also be intermediate products or final products that use these electronic components.

[0042] More preferred embodiments of the resin sheet according to the present invention are as follows. <1> A resin sheet for packaging electronic components, which comprises a rubber-modified aromatic vinyl copolymer resin containing a continuous matrix resin (X) and a rubber-like polymer (Y) as dispersed particles, and which satisfies the following (1) and (2): (1) The continuous matrix resin (X) is a copolymer of 53 to 63% by mass of styrene and 37 to 47% by mass of a (meth)acrylic acid alkyl ester containing methyl methacrylate and butyl acrylate, (2) The proportion of the rubber-like polymer (Y) relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 5% by mass or more and less than 10% by mass. <2> the ratio of the methyl methacrylate to the butyl acrylate (methyl methacrylate / butyl acrylate) is 4 to 6; <1> The resin sheet for packaging electronic components according to claim 1. <3> Furthermore, the following (3) and (4) are satisfied: <1> or <2> The resin sheet for packaging electronic components according to claim 1. (3) The proportion of styrene relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 49.5 to 55.0 mass %. (4) The ratio of the total amount of methyl methacrylate and butyl acrylate to the total mass of the rubber-modified aromatic vinyl copolymer resin is 35 to 44% by mass. <4> the amount of at least one monomer selected from methyl methacrylate and butyl acrylate contained in the rubber-modified aromatic vinyl copolymer resin is 700 ppm or less based on the total mass of the rubber-modified aromatic vinyl copolymer resin; <1> from <3> The resin sheet for packaging electronic components according to any one of the preceding claims. <5> <1> from <4> 10. An electronic component packaging container comprising the resin sheet for packaging electronic components according to any one of claims 1 to 9. <6> <5> An electronic component packaging body comprising the electronic component packaging container according to claim 1. <7> <6> 10. A method for producing an electronic component packaging body according to claim 9, comprising sealing a lid material to the electronic component packaging container at a heat sealing temperature of less than 165°C. [Example]

[0043] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0044] [Creating resin sheets for packaging electronic components] Example 1 A solution of 7.5 parts by mass of styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, trade name "Asaprene 670A", styrene concentration: 39% by mass) dissolved in 45.0 parts by mass of styrene monomer, 34.0 parts by mass of methyl methacrylate, 5.0 parts by mass of butyl acrylate, and 8.5 parts by mass of ethylbenzene was continuously fed into a first polymerizer, and polymerization was carried out with stirring at a polymerization temperature of 125°C for 3 hours. The reaction solution was then continuously charged in its entirety into a plug flow reactor so that the residence time was 5 hours, and further polymerization was carried out. After polymerization reached a conversion of 85%, the reaction solution was fed into a vented extruder, and volatile components were removed at 230°C under reduced pressure. Furthermore, the molten strand was drawn out from the die, cooled with water, and then cut with a cutter to obtain pellets of a rubber-modified aromatic vinyl copolymer resin. The copolymer resin was then fed into a T-die sheet extruder and molded into a resin sheet having a thickness of 0.3 mm and a width of 600 mm. The residual monomer content of the (x2) component in the resin sheet was 280 ppm. The resulting resin sheet was slit into a 24 mm width and molded using a pressure molding machine at a heater temperature of 210°C to produce a 24 mm wide carrier tape. The pocket size of the carrier tape was 15 mm in the machine direction, 11 mm in the width direction, and 5 mm in the depth direction. Using the resulting resin sheet and carrier tape, the folding strength, image clarity, and low-temperature heat sealability were evaluated under the following conditions. The results are shown in Table 1. The blending ratio (mass%) of component (Y) in Table 1 is a value calculated using the following formula (3). [(Y) / (X+Y)]×100 (3) In formula (3), Y is the total amount of all rubber-like polymers (Y) charged, and X is the value obtained by multiplying the total amount of all monomers constituting component (X) charged by the polymerization rate (%).

[0045] (Folding strength) In accordance with JIS-P-8115 (2001), test pieces measuring 150 mm in length, 15 mm in width, and 0.3 mm in thickness were prepared with the machine direction of the resin sheet as the length direction. Next, the MIT folding endurance was measured using an MIT folding fatigue tester (product name "MIT-D") manufactured by Toyo Seiki Seisakusho Co., Ltd. The test was performed at a folding angle of 135 degrees, a folding speed of 175 times / min, and a measuring load of 250 g. The folding endurance was evaluated according to the following evaluation criteria, with a rating of "B" or higher being considered a passing grade. (Evaluation criteria) A: A folding strength of 30 times or more. B: Folding strength is 10 times or more but less than 30 times. C: Folding strength less than 10 times.

[0046] (Image clarity) The image clarity of the resin sheet was measured using an image clarity measuring device in accordance with JIS-K-7374. The image clarity was evaluated according to the following evaluation criteria, and a rating of "B" or higher was considered to be acceptable (excellent transparency). (Evaluation criteria) A: Image clarity is between 70% and 100%. B: Image clarity is between 60% and 70%. C: Image clarity is less than 60%.

[0047] (low temperature heat sealability) Using a taping machine (Nagata Seiki Co., Ltd., product name "NK-600"), a 21.5 mm wide cover tape (Denka Co., Ltd., product name "ALS-S") was heat-sealed to the carrier tape using a seal head width of 0.5 mm x 2, a seal head length of 24 mm, a seal pressure of 0.5 kgf, a feed length of 12 mm, a seal time of 0.3 seconds, and a seal iron temperature of 140°C to 190°C in 5°C intervals. The cover tape was then peeled at a peel angle of 170° to 180° at a peel rate of 300 mm per minute in an atmosphere of 23°C and 50% relative humidity to evaluate low-temperature sealability. Evaluation was based on the following evaluation criteria, with a rating of "B" or higher being considered a pass (excellent low-temperature heat sealability). (Evaluation criteria) A: The temperature at which the peel strength is 0.2N or more is less than 155°C. B: The temperature at which the peel strength is 0.2N or more is 155°C or more and less than 165°C. C: The temperature at which the peel strength is 0.2N or more is 165°C or higher.

[0048] (Examples 2 to 10 and Comparative Examples 1 to 3) A resin sheet and a carrier tape were obtained in the same manner as in Example 1, except that the blending ratios of each component were as shown in Table 1. The resulting resin sheet and carrier tape were evaluated for folding endurance, image clarity, and low-temperature heat sealability in the same manner as in Example 1. The results are shown in Table 1.

[0049] The details of the raw materials shown in Table 1 are as follows: Rubber 1: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "Asaprene 670A", styrene concentration: 39% by mass). Rubber 2: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "Asaprene 625A", styrene concentration: 35% by mass). Rubber 3: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "Asaprene 610A", styrene concentration: 15% by mass).

[0050] [Table 1]

[0051] As shown in Table 1, the resin sheets for packaging electronic components of Examples 1 to 10, which satisfied the configuration of the present invention, had transparency, excellent folding strength, and excellent low-temperature heat sealing properties. On the other hand, the resin sheet of Comparative Example 1, in which the proportions of components (x1) and (x2) in component (X) did not satisfy the configuration of the present invention, had a high heat sealing temperature of 165°C. The resin sheet of Comparative Example 2, in which the blending amount of rubbery polymer (Y) was less than 5% by mass, had low folding strength. Furthermore, the resin sheet of Comparative Example 3, in which the blending amount of rubbery polymer (Y) was more than 10% by mass, had a high heat sealing temperature of 165°C. Furthermore, the resin sheet of Comparative Example 3 also had slightly inferior image clarity. From the above results, it was confirmed that the resin sheet for packaging electronic components according to the present invention has transparency, excellent folding strength, and excellent low-temperature heat sealing properties.

Claims

1. A resin sheet for packaging electronic components, the resin sheet for packaging electronic components being for carrier tape or tray, and The resin sheet for packaging electronic components comprises a continuous matrix resin (X) containing a rubber-like polymer (Y) as dispersed particles, and is composed of a rubber-modified aromatic vinyl copolymer resin that satisfies the following (1) and (2): (1) The continuous matrix resin (X) is a copolymer of 53 to 55.4% by mass of one or more aromatic vinyl compounds (x1) and 44.6 to 47% by mass of one or more alkyl (meth)acrylate esters (x2), the (meth)acrylic acid alkyl ester (x2) comprises methyl methacrylate (x2-1) and a (meth)acrylic acid alkyl ester (x2-2) having a linear or branched alkyl group having 4 to 8 carbon atoms, The proportion of the (meth)acrylic acid alkyl ester (x2-2) relative to the total mass of the (meth)acrylic acid alkyl ester (x2) is 12.8 to 50 mass %. (2) The proportion of the rubber-like polymer (Y) relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is 5% by mass or more and less than 10% by mass.

2. The resin sheet for packaging electronic components according to claim 1, wherein the (meth)acrylic acid alkyl ester (x2-2) includes butyl acrylate.

3. 3. An electronic component packaging container comprising the resin sheet for packaging electronic components according to claim 1 or 2.

4. An electronic component packaging body comprising the electronic component packaging container according to claim 3 .

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