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

Abstract

To provide a resin sheet for electronic component packaging having excellent transparency, folding strength, and low-temperature heat sealability, and an electronic component packaging container using the same. Means for solving the problem is a resin sheet for electronic component packaging composed of a rubber-modified aromatic vinyl copolymer resin containing a rubbery polymer (Y) as dispersed particles in a continuous base resin (X), and satisfying the following (1) to (2); (1) the continuous base resin (X) is a copolymer of one or more aromatic vinyl compounds (x1) 53 to 63 mass% and one or more (meth) alkyl acrylate (x2) 37 to 47 mass%; (2) the proportion of the rubbery polymer (Y) is 5 mass% or more and less than 10 mass% with respect to the total mass of the rubber-modified aromatic vinyl copolymer resin.

Description

Technical Field

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

[0002] Rigid polyvinyl chloride (PVC) has been used in electronic component packaging containers such as IC boxes or IC carrier tapes due to its superior properties, including transparency, impact resistance, rigidity, and surface hardness. However, considering the generation of acidic corrosive gases or toxic substances during waste incineration, alternative materials to PVC are needed. As alternative materials to address these drawbacks, blends of resins selected from at least one resin of polystyrene and styrene-(meth)acrylate copolymers with styrene-butadiene block copolymers are known (e.g., Patent Document 1). However, these blends struggle to simultaneously achieve the rigidity and impact resistance required for electronic component packaging containers. Specifically, these blends exhibit an inverse relationship: increasing rigidity reduces impact resistance, and vice versa, making it difficult to say that they are materials that can achieve a good balance between the rigidity and impact resistance required for electronic component packaging containers. Furthermore, other PVC alternatives include polycarbonate resins and transparent ABS resins, but these are costly and lack practicality as low-cost PVC substitutes.

[0003] Patent Document 2 discloses a rubber-modified styrene resin composition that yields a transparent molded body for electronic component packaging with high strength, transparency, excellent rigidity, and high surface hardness. Patent Document 2 describes a transparent molded body for electronic component packaging formed from a rubber-modified styrene resin composition containing a rubber-modified styrene resin and a terpene resin or a terpene hydrogenated resin. The rubber-modified styrene is obtained by polymerizing a mixed solution containing styrene, alkyl (meth)acrylate, and a butadiene-based rubber polymer. However, the molded body formed from such a rubber-modified styrene resin composition lacks sufficient strength, transparency, and other physical properties, as well as sufficient surface hardness.

[0004] In response, Patent Document 3 discloses a rubber-modified aromatic vinyl copolymer resin, which yields a molded body for electronic component packaging with excellent physical properties such as strength and transparency, and sufficiently high surface hardness. Patent Document 3 describes a method of graft copolymerizing a mixture of aromatic vinyl compounds and (meth)acrylate alkyl ester compounds, particularly a styrene-butadiene block copolymer with a specific structure that has a strong affinity for the aforementioned mixture, as a rubber-like polymer. The resin composition dispersed in the mixture is then subjected to profile extrusion molding to obtain a transparent molded body for electronic component packaging with high strength, excellent transparency, high rigidity, and high surface hardness.

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] Patent Document 1: Japanese Patent Application Publication No. 8-12847

[0008] Patent Document 2: Japanese Patent Application Publication No. 9-301479

[0009] Patent Document 3: Japanese Patent Application Publication No. 2002-193378 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] In electronic component packaging containers, considering the rapid filling of electronic components in recent years, there is a need for low-temperature heat-sealing properties that can achieve high peel strength with short sealing times. Additionally, it is necessary to maintain high transparency so that the electronic components containing them are visible from the outside, while simultaneously balancing physical properties such as flexural strength and formability.

[0012] Therefore, the object of the present invention is to provide a resin sheet for packaging electronic components that has transparency, excellent flexural strength and excellent low-temperature heat-sealing properties, and an electronic component packaging container made therefrom.

[0013] Solution for solving the problem

[0014] Regarding the aforementioned issues, the inventors of this application conducted careful research and discovered that, surprisingly, in a resin sheet composed of a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer as dispersed particles in a continuous matrix resin copolymerized from an aromatic vinyl compound and an alkyl methacrylate, 53-63% by mass of the aforementioned aromatic vinyl compound and 37-47% by mass of the aforementioned alkyl methacrylate are copolymerized, and the rubber-like polymer is made to be 5% or more and less than 10% by mass relative to the total mass of the rubber-modified aromatic vinyl copolymer resin, thereby obtaining a resin sheet with excellent transparency, impact resistance, rigidity, and, consequently, excellent low-temperature heat-sealing properties, thus completing the present invention.

[0015] That is, the present invention has the following solution.

[0016] [1] A resin sheet for packaging electronic components, which is composed of a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X) and satisfying the following (1) to (2);

[0017] (1) The above-mentioned continuous matrix resin (X) is a copolymer of 53-63% by mass of one or more aromatic vinyl compounds (x1) and 37-47% by mass of one or more alkyl methacrylates (x2).

[0018] (2) The proportion of the rubber-like polymer (Y) is 5% by mass or more and less than 10% by mass relative to the total mass of the rubber-modified aromatic vinyl copolymer resin.

[0019] [2] The resin sheet for packaging electronic components according to [1], wherein the above-mentioned alkyl methacrylate (x2) comprises methyl methacrylate (x2-1) and alkyl methacrylate (x2-2) having a straight-chain or branched alkyl group having 4 to 8 carbon atoms.

[0020] [3] According to the resin sheet for packaging electronic components as described in [2], the proportion of the alkyl methacrylate (x2-2) is 5 to 50% by mass relative to the total mass of the alkyl methacrylate (x2).

[0021] [4] The resin sheet for packaging electronic components according to [2] or [3], wherein the alkyl methacrylate (x2-2) comprises butyl acrylate.

[0022] [5] An electronic component packaging container, which is made of any one of the resin sheets for electronic component packaging described in any one of [1] to [4].

[0023] [6] The electronic component packaging container according to [5] is a carrier tape.

[0024] [7] The electronic component packaging container according to [5] is a tray.

[0025] [8] An electronic component package comprising any one of [5] to [7] an electronic component packaging container.

[0026] The effects of the invention

[0027] According to the present invention, a resin sheet for packaging electronic components with excellent transparency, flexural strength and low-temperature heat-sealing properties, and an electronic component packaging container made therefrom can be provided. Detailed Implementation

[0028] The present invention will be described in detail below, but the present invention is not limited to the following methods.

[0029] It should be noted that in this specification, the symbol “~” means “above” or “below”. For example, “5 to 10% by mass” means “more than 5% by mass and less than 10% by mass”.

[0030] Resin sheets for packaging electronic components

[0031] The resin sheet for packaging electronic components (hereinafter sometimes simply referred to as "resin sheet") of the present invention is composed of a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X) and satisfying the following (1) to (2).

[0032] (1) The above-mentioned continuous matrix resin (X) is a copolymer of 53-63% by mass of one or more aromatic vinyl compounds (x1) and 37-47% by mass of one or more alkyl methacrylates (x2).

[0033] (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.

[0034] The resin sheet for packaging electronic components of the present invention, which is composed of a rubber-modified aromatic vinyl copolymer resin having the following characteristics, has transparency, excellent flexural strength, and excellent low-temperature heat-sealing properties.

[0035] <Rubber-modified aromatic vinyl copolymer resin>

[0036] The rubber-modified aromatic vinyl copolymer resin (hereinafter simply referred to as "copolymer resin") of the present invention is characterized in that it contains a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X) and satisfies the following (1) to (2).

[0037] (1) The above-mentioned continuous matrix resin (X) is a copolymer of 53-63% by mass of one or more aromatic vinyl compounds (x1) and 37-47% by mass of one or more alkyl methacrylates (x2).

[0038] (2) The proportion of the rubber-like polymer (Y) is 5% by mass or more and less than 10% by mass relative to the total mass of the rubber-modified aromatic vinyl copolymer resin.

[0039] By satisfying (1) and (2) above, a resin sheet with excellent low-temperature heat-sealing properties, as well as excellent transparency and flexural strength, is obtained.

[0040] (Continuous matrix resin (X))

[0041] The continuous matrix resin (X) is a resin component that forms a continuous phase in a copolymer resin. The continuous matrix resin (X) is a copolymer of one or more aromatic vinyl compounds (x1) (hereinafter sometimes referred to as "(x1) component") and one or more alkyl (meth)acrylates (x2) (hereinafter sometimes referred to as "(x2) component"). Specifically, the continuous matrix resin (X) is obtained by copolymerizing 53 to 63% by mass of the (x1) component and 37 to 47% by mass of the (x2) component relative to the total mass of the continuous matrix resin (X).

[0042] (Aromatic vinyl compounds (x1))

[0043] As an aromatic vinyl compound (x1), one such compound may be used alone, for example: styrene; α-alkyl-substituted styrene such as α-methylstyrene and α-methyl-p-methylstyrene; nucleoalkyl-substituted styrene such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, and p-tert-butylstyrene; nucleohalo-substituted styrene such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, 2-methyl-1,4-chlorostyrene, and 2,4-dibromostyrene; vinylnaphthalene and other styrene compounds that have been conventionally used in rubber-modified styrene-based resins, or two or more may be used in combination. Among these, styrene is preferred.

[0044] The proportion of component (x1) in the continuous matrix resin (X) relative to the total mass of the continuous matrix resin (X) is 53-63% by mass, preferably 53.5-62.5% by mass, more preferably 54-61% by mass, and particularly preferably 54-60% by mass. By setting the proportion of component (x1) within the above range, the proportion of component (x2) in the continuous matrix resin (X) can be adjusted to 37-47% by mass, resulting in a resin sheet with excellent low-temperature heat-sealing properties. A copolymer resin containing 53-63% by mass of styrene as (x1) relative to the total mass of the continuous matrix resin (X) is particularly preferred, preferably 53.5-62.5% by mass. Furthermore, the proportion of component (x1) in component (X) refers to the proportion of component (x1) relative to the total amount (100% by mass) of all monomers constituting component (X). Setting the proportion of component (x1) to 53-63% by mass can be achieved, for example, by adjusting the monomer feed ratio. The proportion of the (x2) component in the (X) component, which will be discussed later, is also the same.

[0045] The proportion of the (x1) component in the copolymer resin, relative to the total mass of the copolymer resin, is preferably 48.0 to 57.0% by mass, more preferably 49.5 to 55.0% by mass, and particularly preferably 50.5 to 54.0% by mass. If the proportion of the (x1) component in the copolymer resin is within the above range, it becomes easier to obtain a resin sheet with better low-temperature heat-sealing properties. Furthermore, the proportion of the (x1) component in the copolymer resin is a value calculated by the following formula (1).

[0046] [(x1) / (X+Y)]×100…(1)

[0047] In Equation (1), x1 is the total amount of all monomers that make up component (x1), X is the total amount of all monomers that make up component (X) multiplied by the polymerization rate (%), and Y is the total amount of all rubbery polymers that make up component (Y).

[0048] ((Meth)alkyl acrylate (x2))

[0049] In the copolymer resins involved in this invention, (meth)acrylate alkyl esters refer to alkyl methacrylates and alkyl acrylates.

[0050] As component (x2), examples include alkyl (meth)acrylates having straight-chain or branched alkyl groups having 1 to 18 carbon atoms. Specifically, examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, tridecyl methacrylate, palmitate methacrylate, pentadecyl methacrylate, stearyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, lauryl acrylate, tridecyl acrylate, palmitate methacrylate, pentadecyl acrylate, stearyl acrylate, etc. These can be used alone or in combination with two or more.

[0051] The proportion of the (x2) component in the continuous matrix resin (X) relative to the total mass of the continuous matrix resin (X) is 37 to 47% by mass, preferably 37.5 to 46.5% by mass, more preferably 39 to 46% by mass, and particularly preferably 40 to 45% by mass. By setting the proportion of the (x2) component within the above range, the proportion of the (x1) component in the continuous matrix resin (X) can be adjusted to 53 to 63% by mass, resulting in a resin sheet with excellent low-temperature heat-sealing properties.

[0052] The proportion of the (x2) component in the copolymer resin, relative to the total mass of the copolymer resin, is preferably 33-44% by mass, more preferably 35-44% by mass. By setting the proportion of the (x2) component in the copolymer resin within the above range, it becomes easier to obtain resin sheets with excellent heat-sealing properties at lower temperatures. Furthermore, when methyl methacrylate and butyl acrylate, described later, are included as (x2) components, the proportion of the (x2) component in the copolymer resin, relative to the total mass of the copolymer resin, can be in the range of 37-43% by mass.

[0053] The proportion of (x2) component in the copolymer resin is calculated by the following formula (2).

[0054] [(x2) / (X+Y)]×100…(2)

[0055] In equation (2), x2 is the total amount of all monomers that make up component (x2), X is the total amount of all monomers that make up component (X) multiplied by the polymerization rate (%), and Y is the total amount of all rubbery polymers that make up component (Y).

[0056] (x2) Component preferably includes methyl methacrylate (x2-1) (also sometimes referred to as "(x2-1) component") and alkyl methacrylate (x2-2) (also sometimes referred to as "(x2-2) component") of straight-chain or branched alkyl groups having 4 to 8 carbon atoms.

[0057] Examples of (x2-2) components include butyl methacrylate and 2-ethylhexyl methacrylate.

[0058] Among alkyl (meth)acrylates, methyl methacrylate (MMA) and alkyl (meth)acrylates having alkyl groups with 4 to 8 carbon atoms tend to have low heat capacity (Tg). As described above, by combining monomers of alkyl (meth)acrylates with low Tg with each other, the resin becomes easier to soften even at low temperatures, making it easier to obtain resin sheets with excellent heat-sealing properties at low temperatures.

[0059] As component (x2-2), alkyl acrylates having straight-chain or branched alkyl groups having 4 to 8 carbon atoms are preferred, butyl acrylate and 2-ethylhexyl acrylate are more preferred, and butyl acrylate is particularly preferred. Furthermore, component (x2) is most preferably a mixture of component (x2-1) and butyl acrylate. By combining component (x2-1) with butyl acrylate, the Tg of the continuous matrix resin (X) is reduced, low-temperature heat-sealing properties are improved, and transparency, flexural strength, etc., are less likely to decrease.

[0060] The proportion of component (x2-2) in component (x2) relative to the total mass of component (x2) is preferably 5-50% by mass, more preferably 10-40% by mass, even more preferably 10-30% by mass, and particularly preferably 10-20% by mass. If the proportion of component (x2-2) in component (x2) is within the above range, the heat-sealing properties at low temperatures tend to improve, and the balance of transparency, flexural strength, etc., also tends to improve. Furthermore, from the viewpoint that heat-sealing at even lower temperatures tends to improve, the proportion of component (x2-2) relative to the total mass of component (x2) can be in the range of 13-18% by mass.

[0061] In this specification, the proportion of component (x2-2) in component (x2) refers to the proportion of component (x2-2) relative to the total amount (100% by mass) of alkyl methacrylates constituting component (x2).

[0062] In one embodiment, when component (x2) is a mixture of components (x2-1) and (x2-2), and component (x2-2) is butyl acrylate, from the viewpoint that heat-sealing properties are more easily improved at lower temperatures, 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. By keeping the ratio of MMA to butyl acrylate within the above range, a lower Tg of the resin sheet is maintained, while sheet strength is easily achieved. Thus, it becomes easier to obtain a resin sheet that combines heat-sealing properties at low temperatures and flexural strength.

[0063] The continuous matrix resin (X) may also contain monomers other than components (x1) and (x2). These other monomers are compounds that can copolymerize with components (x1) and (x2), and examples include: acrylonitrile, methacrylonitrile, fumaric acid, maleic acid, α-chloroacrylonitrile, etc.; ethylene cyanide; methacrylic acid; acrylic acid; maleic anhydride, phenyl maleimide, etc.; vinyl acetate; divinylbenzene, etc. These can be used individually or in combination of two or more. Furthermore, from the viewpoint of easily obtaining a resin sheet that maintains a balance of various physical properties such as image sharpness and flexural strength, and also exhibits excellent low-temperature heat-sealing properties, the continuous matrix resin (X) is particularly preferably composed only of components (x1) and (x2).

[0064] (Rubber-like polymer (Y))

[0065] The copolymer resin involved in this invention comprises, by weight, more than 5% and less than 10% by weight of a rubbery polymer (Y) relative to the total mass of the copolymer resin.

[0066] In electronic component packaging containers, high transparency is required to allow for visual confirmation of the contained electronic components from the outside. In conventional resin sheets composed of rubber-modified aromatic vinyl copolymers, from the viewpoint of sheet strength (impact resistance, rigidity), it is difficult to reduce the amount of rubber component; approximately 12% by mass of rubber component must be added. Therefore, reducing the amount of rubber component makes it difficult to obtain a resin sheet that combines higher transparency (image clarity) and high sheet strength. The inventors of this application have discovered that by controlling the blending ratio of components (x1) and (x2) constituting the continuous matrix resin (X) within a certain range, it becomes easy to obtain a resin sheet with sufficient sheet strength even by reducing the amount of rubber-like polymer (Y). Furthermore, surprisingly, it was also found that by combining components (x1) and (x2) within the aforementioned specific range, the resin becomes easier to soften, making it easier to obtain a resin sheet with excellent heat-sealing properties at lower temperatures. The copolymer resin of the present invention, as described above, has a rubbery polymer (Y) content of 5% by mass or more and less than 10% by mass, and therefore also has good transparency.

[0067] The rubbery polymer (Y) is preferably a copolymer of styrene and butadiene. The proportion of the rubbery polymer (Y) in the copolymer resin, relative to the total mass of the copolymer resin, is preferably 5 to 9% by mass, more preferably 5.5 to 8.5% by mass, and particularly preferably 5.5 to 8.0% by mass.

[0068] Furthermore, the amount of rubbery polymer (Y) in the copolymer resin can also be calculated using the value obtained from the following formula (3).

[0069] [(Y) / (X+Y)]×100…(3)

[0070] In equation (3), Y is the total amount of feed of all rubbery polymer (Y), and X is the total amount of feed of all monomers constituting component (X) multiplied by the polymerization rate (%).

[0071] The rubbery polymer (Y) contained in the copolymer resin of the present invention is preferably a styrene-butadiene copolymer (SBR). Furthermore, the styrene concentration in the SBR, relative to the total mass of the SBR, is preferably 10-50% by mass, more preferably 10-45% by mass, and even more preferably 15-40% by mass. 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 smaller, and transparency tends to improve.

[0072] <Preparation Method of Rubber-Modified Aromatic Vinyl Copolymer Resin>

[0073] The copolymer resin of the present invention is obtained, for example, by polymerizing a mixture of raw materials containing components (x1) and (x2) in the presence of a rubbery polymer (Y), thereby obtaining a copolymer resin in which the rubbery polymer (Y) is contained as dispersed particles in a continuous matrix resin (X).

[0074] The ratio of component (x1) to component (x2) in the raw material mixture can be adjusted so that component (x1) in the continuous matrix resin (X) is 53-63% by mass and component (x2) is 37-47% by mass.

[0075] The rubber-like polymer (Y) can be commercially available or manufactured using methods such as living anionic polymerization.

[0076] As a commercially available product, it may use, for example, the trade name "ASAPRENE (registered trademark)" manufactured by Asahi Kasei Corporation.

[0077] When manufacturing the rubbery polymer (Y), methods such as living anionic polymerization of a monomer mixture containing styrene and butadiene in a hydrocarbon solvent in the presence of an organolithium-based catalyst can be used. Specifically, methods described in Japanese Patent Application Publication No. 2002-193378, etc., can be employed.

[0078] Organic solvents may be included in the above-mentioned raw material mixture as needed. 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. Toluene and ethylbenzene are preferred. By using organic solvents, it becomes easier to control the monomer concentration and polymer concentration in the polymerization solution, and thus easier to control the polymerization reaction. When using organic solvents, the amount used may be in the range of 5 to 50 parts by mass relative to the total amount (100 parts by mass) of the raw material mixture used to manufacture the copolymer resin. More preferably, it may be in the range of 5 to 10 parts by mass.

[0079] Furthermore, other solvents such as aliphatic hydrocarbons, dialkyl ketones, and aromatic hydrocarbons can be used in combination without compromising the solubility of the rubbery polymer (Y).

[0080] The raw material mixture may also contain a polymerization initiator. Organic peroxides are preferred as polymerization initiators.

[0081] Examples of organic peroxides include: 2,2-bis(tert-butylperoxide)butane, 2,2-bis(tert-butylperoxide)octane, 1,1-bis(tert-butylperoxide)3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxide)valerate, and other peroxide ketals; di-tert-butylperoxide, tert-butylisopropylphenyl peroxide, diisopropylbenzene peroxide, α,α'-bis(tert-butylperoxide isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, 2,5-dimethyl-2,5-bis( Dialkyl peroxides such as tert-butyl peroxide (hexyne-3); diacyl peroxides such as acetyl peroxide, isobutyryl peroxide, octyl peroxide, decyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-toluyl peroxide; diisopropyl peroxide, di-2-ethylhexyl peroxide, di-n-propyl peroxide, di-3-methoxybutyl peroxide, di-2-ethoxyethyl peroxide, and di-methoxyisopropyl peroxide. Peroxide carbonates such as esters, di(3-methyl-3-methoxybutyl) peroxide dicarbonate, and bis(4-tert-butylcyclohexyl) peroxide dicarbonate; tert-butyl peroxyacetate, tert-butyl peroxyisobutyrate, tert-butyl peroxypentanoate, tert-butyl peroxyneodecanate, cumyl peroxyneodecanate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate, di-tert-butyl isophthalate diperoxide, and 2,5-dimethyl-2,5-di(benzoyl) The peroxides include hexane peroxide, tert-butyl peroxide isopropyl carbonate, and other peroxide esters; ketone peroxides such as acetylacetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methyl cyclohexanone peroxide; hydrogen peroxides such as tert-butyl hydroperoxide, cumene hydroperoxide, dicumene hydroperoxide, p-menthane hydroperoxide, 2,5-dimethylhexane 2,5-dihydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide; polyacryl peroxides of diacids; and polyperoxides of diacids and polyols. These organic peroxides can be used as polymerization initiators, either alone or in combination of two or more. There are no particular limitations on the amount of each compound, as long as the desired effect of the invention is achieved; preferably, it is 0.001 to 5.0 parts by mass relative to 100 parts by mass of the above-mentioned raw material mixture.

[0082] In addition, chain transfer agents, antioxidants, etc. can be incorporated during polymerization.

[0083] Examples of chain transfer agents include thiols, α-methylstyrene linear dimers, and monoterpene molecular weight regulators (terpinene). These can be used individually or in combination of two or more.

[0084] Examples of antioxidants include hindered phenols, hindered bisphenols, and hindered triphenols. Specifically, 2,6-di-tert-butyl-4-cresol and stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate can also be used.

[0085] The copolymer resin involved in this invention may contain additives such as antioxidants, inorganic stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, and organopolysiloxanes, as needed.

[0086] As antioxidants, the same antioxidants as those mentioned above can be cited.

[0087] Examples of inorganic stabilizers include calcium and tin.

[0088] Examples of UV absorbers include p-tert-butyl phenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenone, and 2-(2'-hydroxy-4'-n-octyloxyphenyl)benzothiazole.

[0089] Examples of flame retardants include antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, chlorinated paraffin, tetrabromobutane, hexabromobutane, and tetrabromobisphenol A.

[0090] Examples of antistatic agents include stearamidopropyl dimethyl-β-hydroxyethyl ammonium nitrate.

[0091] Examples of colorants include titanium dioxide, carbon black, and other inorganic or organic pigments.

[0092] Examples of fillers include: calcium carbonate, clay, silica, glass fiber, glass beads, carbon fiber, methyl methacrylate-butadiene-styrene copolymer (MBS), styrene-butadiene-styrene copolymer (SBS), styrene-isoprene copolymer (SIS), or hydrides of these, etc., used as reinforcing elastomers.

[0093] The above-mentioned additives can be used alone or in combination of two or more. Alternatively, they can be added during manufacturing.

[0094] The copolymer resins involved in this invention may, if necessary, contain plasticizers and lubricants.

[0095] As plasticizers, those already known can be used, such as: dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, butylparaben, butyl phthaloyl glycolate, and other phthalic acid-based plasticizers; di-n-butyl adipate, di-(2-ethylhexyl) adipate, and other adipic acid-based plasticizers; acetyl tri-n-butyl citrate, and other citric acid-based plasticizers; di-n-butyl sebacate, di-... Sebacic acid-based plasticizers such as (2-ethylhexyl) ester; epoxy-based plasticizers such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized fatty acid esters; polyester-based plasticizers containing dibasic acids such as succinic acid, glutaric acid, and adipic acid, and diols with molecular weights below 200 such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol; terpene-based resins and hydrogenated terpene-based resins. These plasticizers can be used alone or in combination of two or more.

[0096] Furthermore, the copolymer resin of the present invention may also contain monomers of (meth)acrylate (x2). By using monomers containing the (x2) component as plasticizers, the resin sheets of the present invention become easier to soften and easier to heat-seal at low temperatures. The above-mentioned monomers may be added to the copolymer resin or may be residual monomers from the manufacturing process. When the copolymer resin contains monomers of the (x2) component, the 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. Moreover, when the above-mentioned monomers are residual monomers from the manufacturing process, the proportion of residual monomers in the copolymer resin can be controlled within the above-mentioned range by adjusting the polymerization temperature, polymerization time, etc.

[0097] As lubricants, those already known can be used, such as: metal soap-based and hydrocarbon-based liquid paraffin; polyethylene wax; fatty acid-based higher fatty acids and hydroxy fatty acids; ester-based glycerides and ester waxes; fatty acid amide-based fatty acid amides and bis-fatty acid amides; fatty acid ketone-based and complex lubricant systems, etc. Specific examples include paraffin wax, stearic acid, hardened oil, stearamide, ethylene bis-stearamide, n-butyl stearate, ketone waxes, octanol, lauryl alcohol, triglyceride hydroxystearate, polysiloxanes, and alkyl phosphates. These lubricants can be used alone or in combination of two or more.

[0098] In the case of the presence of plasticizers and lubricants, from the viewpoint of the processability of the resin sheet and the sealing of the packaging container, the amount of these additives is preferably in the range of 0.05 to 1.0 parts by weight relative to the total mass of the copolymer resin.

[0099] [Manufacturing method of resin sheet]

[0100] The resin sheet involved in this invention is composed of the aforementioned copolymer resin. Conventionally known methods can be used as a method for manufacturing the resin sheet. Specifically, the copolymer resin is fed into an extruder for melt mixing to produce resin granules. Examples include further feeding the resin granules into a sheet extruder such as a T-die, extruding it to the desired thickness, and molding it to produce a resin sheet. Furthermore, a conductive layer can be formed on at least one surface of the resin sheet to produce a conductive resin sheet.

[0101] From the viewpoint of the formability and strength of the packaging container, the thickness of the resin sheet involved in this invention is preferably 0.1 to 1 mm, more preferably 0.15 to 0.8 mm.

[0102] <Flexural Strength>

[0103] The resin sheet of the present invention exhibits excellent flexural strength. Specifically, the flexural strength of the resin sheet of the present invention, measured according to JIS-P-8115, is preferably 10 cycles or more, more preferably 30 cycles or more, and even more preferably 50 cycles or more. Furthermore, the flexural strength of the resin sheet refers to the value measured under the following conditions.

[0104] (Method for determining flexural strength)

[0105] According to JIS-P-8115 (2001), the flow direction of the resin sheet was taken as the length direction, and test pieces with a length of 150 mm, a width of 15 mm, and a thickness of 0.3 mm were prepared. The flexural strength of the MIT sheet was determined using an MIT flexural fatigue testing machine manufactured by Toyo Seiki Co., Ltd. The test was conducted at a bending angle of 135 degrees, a bending speed of 175 times / minute, and a test load of 250 g.

[0106] <Image sharpness>

[0107] The resin sheet of the present invention, according to JIS-K-7324, preferably has an image sharpness of 60% or more, more preferably 70% or more, and even more preferably 75% or more, as measured by an image sharpness measuring instrument. With an image sharpness of 60% or more, it becomes easier to visually identify electronic components housed in a bag within an electronic component packaging container. That is, the resin sheet having such image sharpness exhibits excellent transparency.

[0108] [Packaging containers for electronic components]

[0109] By molding the resin sheet involved in this invention using known sheet molding methods (thermoforming) such as vacuum forming, air forming, and pressure forming, it is possible to obtain electronic component packaging containers with free shapes such as carrier tapes and trays. The resin sheet involved in this invention has transparency, excellent flexural strength, and excellent low-temperature heat-sealing properties, thus enabling the provision of electronic component packaging containers with these superior physical properties.

[0110] <Low-temperature heat sealability>

[0111] The electronic component packaging container of the present invention exhibits excellent low-temperature heat-sealing properties. Specifically, the sealing temperature at which the peel strength of the cap tape, measured under the following conditions, is 0.2 N or higher is preferably less than 165°C, more preferably less than 155°C, and even more preferably less than 145°C.

[0112] (Method for determining low-temperature heat-sealing properties)

[0113] Using a wrapping machine, with 0.5mm wide seal heads (2 x 0.5mm), 24mm long seal heads, a sealing pressure of 0.5kgf, a conveyor length of 12mm, a sealing time of 0.3 seconds, and a sealing soldering iron temperature of 140℃~190℃, a 21.5mm wide cover tape was heat-sealed from the carrier tape at 5℃ intervals. Then, in an environment of 23℃ and 50% relative humidity, the cover tape was peeled at a peeling speed of 300mm per minute and a peeling angle of 170°~180° to confirm that the peel strength reached a sealing temperature of 0.2N or higher.

[0114] [Electronic Component Packaging]

[0115] Electronic component packaging containers house electronic components and serve as packaging bodies for the storage and transport of these components. For example, a carrier tape, after housing electronic components in a bag formed using the aforementioned molding method, is covered with a cap tape, forming a rolled carrier tape used for the storage and transport of electronic components. The resin sheet and electronic component packaging container of the present invention exhibit excellent heat-sealing properties at low temperatures. Therefore, the heat-sealing temperature when used as an electronic component packaging body is preferably less than 165°C, more preferably less than 155°C, and even more preferably less than 145°C.

[0116] Another aspect of the present invention is a method for manufacturing an electronic component packaging body, which is a method for manufacturing an electronic component packaging body using an electronic component packaging container comprising a resin sheet made of the above-mentioned copolymer resin, comprising heat-sealing the cover material of the electronic component packaging container at a heat-sealing temperature of less than 165°C, preferably less than 155°C.

[0117] Electronic components packaged within electronic component packaging are not specifically limited to, but include, for example: ICs, LEDs (light-emitting diodes), resistors, liquid crystal displays, capacitors, transistors, piezoelectric resistors, filters, quartz oscillators, diodes, connectors, switches, volume control units, relays, inductors, etc. Additionally, intermediate or final products using these electronic components can also be included.

[0118] A more preferred embodiment of the resin sheet involved in this invention is described below.

[0119] <1> A resin sheet for packaging electronic components, which is composed of a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X) and satisfying the following (1) to (2);

[0120] (1) The above-mentioned continuous matrix resin (X) is a copolymer of 53-63% by mass of styrene and 37-47% by mass of alkyl (meth)acrylate containing methyl methacrylate and butyl acrylate.

[0121] (2) The proportion of the rubber-like polymer (Y) is 5% by mass or more and less than 10% by mass relative to the total mass of the rubber-modified aromatic vinyl copolymer resin.

[0122] <2> The resin sheet for packaging electronic components according to <1>, wherein the value of methyl methacrylate (methyl methacrylate / butyl acrylate) relative to the butyl acrylate is 4 to 6.

[0123] <3> The resin sheet for packaging electronic components according to <1> or <2> further satisfies the following (3) and (4).

[0124] (3) The proportion of styrene relative to the total mass of the above-mentioned rubber-modified aromatic vinyl copolymer resin is 49.5 to 55.0% by mass.

[0125] (4) The total mass ratio of methyl methacrylate and butyl acrylate relative to the total mass of the above-mentioned rubber-modified aromatic vinyl copolymer resin is 35-44 by mass.

[0126] <4> The resin sheet for packaging electronic components according to any one of <1> to <3>, wherein 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 relative to the total mass of the rubber-modified aromatic vinyl copolymer resin.

[0127] <5> An electronic component packaging container, which is made of a resin sheet for electronic component packaging according to any one of <1> to <4>.

[0128] <6> An electronic component packaging body comprising the electronic component packaging container according to <5>.

[0129] <7> A method for manufacturing an electronic component packaging body, which is the method for manufacturing an electronic component packaging body described in <6>, comprising sealing the electronic component packaging container with a heat sealing temperature of less than 165°C.

[0130] [Example]

[0131] The present invention will be described in detail below with reference to embodiments, but the present invention is not limited to the following description.

[0132] Fabrication of Resin Sheets for Electronic Component Packaging

[0133] (Example 1)

[0134] A solution containing 7.5 parts by weight of styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, trade name "ASAPRENE 670A", styrene concentration: 39% by mass) dissolved in 100 parts by mass of a solution containing 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, along with 0.005 parts by mass of 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane and 0.08 parts by mass of tert-dodecyl mercaptan, was continuously fed into a first polymerizer and polymerized with stirring at a polymerization temperature of 125°C for 3 hours. Then, in a plug-flow reactor, the entire reaction solution was continuously fed in to further polymerize, ensuring a residence time of 5 hours. After polymerization reached 85%, the reaction solution was fed into a vented extruder to remove volatile components at 230°C under reduced pressure. Then, after the molten strands are extracted from the die and cooled with water, they are cut with a knife to obtain granular rubber-modified aromatic vinyl copolymer resin.

[0135] Next, the obtained copolymer resin is fed into a sheet extruder with a T-die to form a resin sheet with a thickness of 0.3 mm and a width of 600 mm. Furthermore, the monomer residue of the (x2) component in the obtained resin sheet is 280 ppm.

[0136] The obtained resin sheet was cut to a width of 24 mm and formed into a 24 mm wide carrier tape using a vacuum forming machine at a heater temperature of 210 °C. The bag dimensions of the carrier tape were 15 mm in the flow direction, 11 mm in the width direction, and 5 mm in the depth direction. Using the obtained resin sheet and carrier tape, the flexural strength, image sharpness, and low-temperature heat-sealing properties were evaluated under the following conditions. The results are shown in Table 1. Furthermore, the blending ratio (mass%) of component (Y) in Table 1 is the value calculated by the following formula (3).

[0137] [(Y) / (X+Y)]×100…(3)

[0138] In equation (3), Y is the total amount of feed of all rubbery polymer (Y), and X is the total amount of feed of all monomers constituting component (X) multiplied by the polymerization rate (%).

[0139] (Flexural strength)

[0140] According to JIS-P-8115 (2001), test pieces with a length of 150 mm, a width of 15 mm, and a thickness of 0.3 mm were prepared, with the flow direction of the resin sheet taken as the length direction. Next, the MIT flexural fatigue testing machine (product name "MIT-D") manufactured by Toyo Seiki Co., Ltd. was used to determine the MIT flexural strength. The test was conducted at a bending angle of 135 degrees, a bending speed of 175 times / minute, and a testing load of 250 g. Furthermore, the flexural strength was evaluated according to the following evaluation criteria, with a "B rating" or higher considered acceptable.

[0141] (Evaluation Criteria)

[0142] A: Those with a flexural strength of 30 cycles or more.

[0143] B: Those with a flexural strength of 10 or more but less than 30 times.

[0144] C: Those with a flexural strength of less than 10 cycles.

[0145] (Image sharpness)

[0146] The image sharpness of the resin sheet was measured using an image sharpness measuring instrument according to JIS-K-7374. Furthermore, the image sharpness was evaluated according to the following evaluation criteria, with a rating of "B" or higher considered acceptable (excellent transparency).

[0147] (Evaluation Criteria)

[0148] A: Images with a sharpness of 70% or higher but less than 100%.

[0149] B: Image sharpness is 60% or higher but less than 70%.

[0150] C: Images with a sharpness of less than 60%.

[0151] (Low-temperature heat sealability)

[0152] Using a wrapping machine (manufactured by Nagata Seiki Co., Ltd., product name "NK-600"), a 21.5mm wide cover tape (manufactured by Denka Co., Ltd., product name "ALS-S") was heat-sealed with a carrier tape at 5°C intervals. The cover tape had a width of 0.5mm x 2, a length of 24mm, a sealing pressure of 0.5kgf, a conveyor length of 12mm, a sealing time of 0.3 seconds, and a sealing soldering iron temperature of 140°C to 190°C. Then, under an atmosphere of 23°C and 50% relative humidity, the cover tape was peeled at a peeling speed of 300mm per minute and a peeling angle of 170° to 180° to evaluate its low-temperature sealing performance. Evaluation was conducted according to the following criteria, with "B rating or above" designated as acceptable (excellent low-temperature heat-sealing performance).

[0153] (Evaluation Criteria)

[0154] A: Peel strength of 0.2N or higher at temperatures below 155℃.

[0155] B: The peel strength is 0.2N or higher at temperatures above 155°C and below 165°C.

[0156] C: Peel strength of 0.2N or above is achieved at temperatures above 165℃.

[0157] (Examples 2-10 and Comparative Examples 1-3)

[0158] The blending ratios of the components were as shown in Table 1. Otherwise, the same procedures as in Example 1 were performed to obtain resin sheets and carrier tapes. The flexural strength, image sharpness, and low-temperature heat-sealing properties of the obtained resin sheets and carrier tapes were evaluated using the same methods as in Example 1. The results are shown in Table 1.

[0159] The details of the raw materials shown in Table 1 are as follows.

[0160] Rubber 1: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "ASAPRENE 670A", styrene concentration: 39% by mass).

[0161] Rubber 2: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "ASAPRENE 625A", styrene concentration: 35% by mass).

[0162] Rubber 3: Styrene-butadiene block copolymer rubber (manufactured by Asahi Kasei Corporation, product name "ASAPRENE 610A", styrene concentration: 15% by mass).

[0163] [Table 1]

[0164]

[0165] As shown in Table 1, the resin sheets for electronic component packaging in Examples 1 to 10, which satisfy the configuration of the present invention, exhibit transparency, excellent flexural strength, and excellent low-temperature heat-sealing properties. On the other hand, the resin sheet of Comparative Example 1, whose proportions of components (x1) and (x2) in component (X) do not satisfy the configuration of the present invention, has a heat-sealing temperature as high as 165°C. The resin sheet of Comparative Example 2, with a rubber-like polymer (Y) blending amount of less than 5% by mass, has low flexural strength. Furthermore, the resin sheet of Comparative Example 3, with a rubber-like polymer (Y) blending amount exceeding 10% by mass, has a heat-sealing temperature as high as 165°C. Additionally, the image sharpness of the resin sheet of Comparative Example 3 is slightly inferior. Based on the above results, it is confirmed that the resin sheet for electronic component packaging according to the present invention exhibits transparency, excellent flexural strength, and excellent low-temperature heat-sealing properties.

Claims

1. A resin sheet for packaging electronic components, comprising a rubber-modified aromatic vinyl copolymer resin containing a rubber-like polymer (Y) as dispersed particles in a continuous matrix resin (X) and satisfying the following (1) to (2); (1) The continuous matrix resin (X) is a copolymer of one or more aromatic vinyl compounds (x1) in an amount of 53 to 55.4% by mass relative to the total mass of the continuous matrix resin (X) and one or more alkyl methacrylates (x2) in an amount of 44.6 to 47% by mass relative to the total mass of the continuous matrix resin (X). The (meth)acrylate alkyl ester (x2) comprises methyl methacrylate (x2-1) and (meth)acrylate alkyl ester (x2-2) having a straight-chain or branched alkyl group having 4 to 8 carbon atoms. The proportion of the alkyl methacrylates (x2-2) relative to the total mass of the alkyl methacrylates (x2) is 5-50% by mass. The rubber-modified aromatic vinyl copolymer resin contains the monomer of the (meth)acrylate (x2), and the proportion of the (meth)acrylate (x2) monomer relative to the total mass of the rubber-modified aromatic vinyl copolymer resin is less than 700 ppm. (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 rubbery polymer (Y) is a styrene-butadiene copolymer, wherein the concentration of styrene is 15-39% by mass relative to the styrene-butadiene copolymer.

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

3. An electronic component packaging container made of the resin sheet for electronic component packaging as described in claim 1 or 2.

4. The electronic component packaging container according to claim 3, wherein it is a carrier belt.

5. The electronic component packaging container according to claim 3, wherein it is a pallet.

6. An electronic component packaging body comprising an electronic component packaging container according to any one of claims 3 to 5.

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