JP6999377B2 - Packaging materials for resin sheets and electronic components - Google Patents

Description

The present invention relates to a resin sheet and a packaging material for electronic parts.

In general, vinyl aromatic hydrocarbon resins (for example, styrene resins) are excellent in molding processability, rigidity, transparency, etc., inexpensive, low in specific gravity, and economically excellent, and are vinyl aromatic hydrocarbons. Sheets molded from resins (eg, styrene-based resins) are widely used in various fields.

Until now, carrier tapes for mounting electronic components such as integrated circuits (ICs) and large-scale integrated circuits (LSIs) on electronic devices have been vinyl chloride resin, polycarbonate resin, and translucent vinyl aromatic hydrocarbon-based resin. The mainstream is a sheet made of (for example, a styrene resin) or the like. For example, the translucent styrene resin sheet is formed of a styrene resin sheet composed of a composition obtained by mixing a general-purpose polystyrene resin, a rubber-modified impact-resistant polystyrene resin, and a styrene-butadiene block copolymer. There is. The carrier tape is required to have good physical properties such as transparency (visibility), rigidity, impact resistance, and moldability in a well-balanced manner due to its usage pattern, and improvement of these characteristics and good physical properties are required. Various studies have been made to obtain a balance.

For example, in order to obtain a carrier tape having excellent transparency, moldability, and impact resistance, an embossed carrier composed of an impact-resistant polystyrene resin having a specific graft ratio and a specific average rubber particle size and a styrene-butadiene block copolymer. Known tapes and carrier tapes made of two types of styrene-butadiene copolymers having different polymer structures, polystyrene, and impact-resistant polystyrene.

Further, with the aim of improving transparency, a resin sheet for carrier tape made of an impact-resistant polystyrene resin containing a block copolymer, a styrene resin, and rubber particles having a specific average particle size is disclosed (for example, a patent). Document 1).

Japanese Unexamined Patent Publication No. 2008-274215

However, in order to further improve the efficiency of electronic component mounting, lengthening is required, and there is also a strong demand for miniaturization of ICs due to high-density mounting. Since the vinyl aromatic hydrocarbon resin sheet (for example, styrene resin sheet) has high rigidity and excellent molding processability, the vinyl aromatic hydrocarbon resin sheet (for example, styrene resin sheet) having excellent transparency is excellent. There is a demand for packaging materials for electronic parts such as carrier tapes made of.

Therefore, an object of the present invention is to take advantage of the high rigidity and excellent molding processability of a vinyl aromatic hydrocarbon resin (for example, a styrene resin), and to package a resin sheet having transparency and an electronic component packaging thereof. It is to provide materials.

The present inventors have a resin sheet (for example, a styrene-based resin sheet) having particularly high transparency in a resin sheet (for example, a styrene-based resin sheet) containing a block copolymer composition composed of a specific copolymer. ) And a packaging material for electronic parts obtained by using this resin sheet, and completed the present invention.

That is, the present invention is as follows.
[1]
A resin sheet containing a block copolymer composition containing a block copolymer a and a copolymer b.
The block copolymer a is a block including a polymer block mainly composed of at least one vinyl aromatic hydrocarbon monomer unit and a polymer block mainly composed of at least one conjugated diene monomer unit. It is a polymer,
The mass ratio of the vinyl aromatic hydrocarbon monomer unit in the block copolymer a to the conjugated diene monomer unit is the former / the latter = 50/50 to 95/5.
The copolymer b is a random copolymer of a vinyl aromatic hydrocarbon monomer unit and a (meth) acrylic acid and / or a (meth) acrylic acid alkyl ester monomer unit.
The mass ratio of the vinyl aromatic hydrocarbon monomer unit in the copolymer b to the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit is the former / the latter = 50. It is / 50 to 90/10,
A resin sheet having an internal haze value of 4.0% or less measured in accordance with ISO 14782.
[2]
The resin sheet according to [1], wherein the number of folding resistances measured in accordance with JIS P 8115 is 500 or more in both the MD direction and the TD direction.
[3]
The resin sheet of [1] or [2], wherein the block copolymer a has at least two polymer blocks mainly composed of vinyl aromatic hydrocarbon monomer units.
[4]
In the molecular weight distribution curve measured by the gel permeation chromatography measurement method,
At least one peak molecular weight derived from the block copolymer a exists within the range of the molecular weight of 30,000 or more and 300,000 or less.
The number average molecular weight (Mn) of the polymer block S composed of vinyl aromatic hydrocarbon monomer units in the block copolymer a is 10,000 or more and 60,000 or less.
The resin sheet according to any one of [1] to [3], wherein the polymer block S has a molecular weight distribution (Mw / Mn) of 1.5 or more and 4.0 or less.
[5]
The resin sheet according to any one of [1] to [4], wherein the internal haze value measured according to ISO 14782 is 2.0% or less.
[6]
Any of [1] to [5], wherein the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit, which is a constituent unit of the copolymer b, is a methyl methacrylate monomer unit. The resin sheet.
[7]
A packaging material for electronic parts, which is a molded body of the resin sheet according to any one of [1] to [6].

According to the present invention, it is possible to provide a resin sheet capable of simultaneously satisfying excellent rigidity, molding processability, and transparency, and an electronic component packaging material (for example, a carrier tape or the like) which is a molded body thereof.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

[Resin sheet]
The resin sheet of the present embodiment is a resin sheet containing a block copolymer composition containing a block copolymer a and a copolymer b, and the block copolymer a is at least one vinyl aromatic hydrocarbon. It is a block copolymer containing a polymer block mainly composed of a monomer unit and a polymer block mainly composed of at least one conjugated diene monomer unit, and is a vinyl aromatic carbonization in the block copolymer a. The mass ratio of the hydrogen monomer unit and the conjugated diene monomer unit is the former / the latter = 50/50 to 95/5, and the copolymer b is a vinyl aromatic hydrocarbon monomer unit. It is a random copolymer with (meth) acrylic acid and / or (meth) acrylic acid alkyl ester monomer unit, and the vinyl aromatic hydrocarbon monomer unit in the copolymer b and (meth) acrylic acid. And / or the mass ratio with the (meth) acrylic acid alkyl ester monomer unit is the former / the latter = 50/50 to 90/10, and the internal haze value measured according to ISO14782 is 4.0. % Or less. By having the above-mentioned structure, the resin sheet of the present embodiment can simultaneously satisfy excellent rigidity, molding processability, and transparency.

[Block Copolymer Composition]
The block copolymer composition of the present embodiment contains the block copolymer a and the copolymer b. The block copolymer a is a block copolymer containing a polymer block mainly composed of at least one vinyl aromatic hydrocarbon monomer and a polymer block mainly composed of at least one conjugated diene monomer. The block copolymer a has a mass ratio of the vinyl aromatic hydrocarbon monomer unit and the conjugated diene monomer unit of the former / the latter = 50/50 to 95/5. Further, the copolymer b is a random copolymer of a vinyl aromatic hydrocarbon monomer and a (meth) acrylic acid and / or (meth) acrylic acid alkyl ester monomer unit, and is a copolymer b. The mass ratio of the vinyl aromatic hydrocarbon monomer unit to the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit is the former / the latter = 50/50 to 90/10. be.

In the present specification, the naming of each monomer unit constituting the polymer follows the naming of the monomer from which the monomer unit is derived. For example, the "vinyl aromatic hydrocarbon monomer unit" means a structural unit of a polymer produced as a result of polymerizing a vinyl aromatic hydrocarbon monomer which is a monomer, and its structure is a substituted vinyl group. It is a molecular structure in which the two carbons of the substituted ethylene group derived from the above are the main chains of the polymer. Further, the "conjugated diene monomer unit" means a structural unit of a polymer produced as a result of polymerizing a conjugated diene which is a monomer, and its structure is two of olefins derived from the conjugated diene monomer. It is a molecular structure in which carbon is the main chain of the polymer. Further, the "(meth) acrylic acid alkyl ester monomer unit" indicates a structural unit of a polymer produced as a result of polymerization of the (meth) acrylic acid alkyl ester monomer which is a monomer, and its structure is: It is a molecular structure in which two carbons of a substituted ethylene group derived from a substituted vinyl group form a polymer main chain.

In addition, in this specification, "mainly" means that the content of a predetermined monomer unit is 90% by mass or more. For example, in the block copolymer a, the "polymer block mainly composed of vinyl aromatic hydrocarbon monomer units" means a block having 90% by mass or more of vinyl aromatic hydrocarbon monomer units. A polymer block having a vinyl aromatic monomer unit of less than 90% by mass and a conjugated diene monomer unit of more than 10% by mass is defined as a random copolymer block. The random copolymer block may have a completely random structure or a tapered structure (the copolymer composition ratio changes stepwise along the chain).

(Mass ratio of block copolymer a and copolymer b)
The mass ratio of the block copolymer a and the copolymer b is not particularly limited, but the former / latter = 20/80 to 75/25 is preferable, and 30/70 to 70/30 is more preferable. , 35/65 to 65/35, more preferably 35/65 to 60/40, and the content of the block copolymer a is 20% by mass or more, so that the resistance of the resin sheet is high. The folding strength is further improved, and the folding resistance measured according to JIS P 8115 tends to satisfy 500 times or more in both the extrusion direction (MD) and the extrusion vertical direction (TD). On the other hand, when the content of the copolymer b is 25% by mass or more, a resin sheet (for example, a styrene-based resin sheet) containing the block copolymer composition of the present embodiment is molded into a packaging material for electronic parts. At the same time, the processability is further improved, and a more sufficient buckling strength as a packaging material for electronic parts tends to be easily obtained. Further, by setting the mass ratio within the above range, the molding processability as a block copolymer composition is further improved, and as a result, a resin sheet (for example, a styrene-based resin sheet) having further better thickness accuracy is obtained. It tends to be. Furthermore, while maintaining high rigidity and good molding processability as a resin sheet (for example, styrene resin sheet), it exhibits high transparency and excellent folding resistance, and is packaged for electronic parts such as carrier tape. It can be suitably used for materials.

[Block copolymer a]
The block copolymer a is a block copolymer composed of a polymer block mainly composed of at least one vinyl aromatic hydrocarbon monomer and a polymer block mainly composed of at least one conjugated diene monomer. .. The content of the vinyl aromatic hydrocarbon monomer unit is 50% by mass or more and 95% by mass or less with respect to the total amount of the vinyl aromatic hydrocarbon monomer unit and the conjugated diene monomer unit in the block copolymer a. The content of the conjugated diene monomer unit is 5% by mass or more and 50% by mass or less. The block copolymer a can be polymerized other than the vinyl aromatic monomer unit (unit derived from the vinyl aromatic monomer) and the conjugated diene monomer unit (unit derived from the conjugated diene monomer). The monomer unit of may be contained as needed.

The vinyl aromatic monomer is not particularly limited as long as it has an aromatic ring and a vinyl group in the molecule, and is, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethyl. Styrene, p-ethylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 1,3-dimethylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene, vinylanthracene, and 1 , 1-diphenylethylene. These monomers may be used alone or in combination of two or more. Among these, styrene is preferable.

The conjugated diene monomer is not particularly limited as long as it is a diolefin having a pair of conjugated double bonds, and is, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3. -Dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like can be mentioned. These conjugated diene monomers may be used alone or in combination of two or more. Among these, 1,3-butadiene and / or isoprene are preferable.

The mass ratio of the vinyl aromatic monomer unit and the conjugated diene monomer unit in the block copolymer a is the former / the latter = 50/50 to 95/5. When the mass ratio is within the above range, a resin sheet having high transparency (for example, a styrene-based resin sheet) tends to be obtained. From the same viewpoint, the mass ratio is preferably 55/45 to 90/10, more preferably 60/40 to 85/15, still more preferably 65/35 to 80/20, and particularly preferably. It is 67/33 to 78/22.

The content of the vinyl aromatic monomer unit and the conjugated diene monomer unit can be quantified by the method described in Examples described later.

The block copolymer a is not particularly limited, and examples thereof include block copolymers having a block structure represented by the following general formulas (1) to (8).
S1-B1 ... (1)
S1-B / S1 ... (2)
S1-B1-S2 ... (3)
S1-B / S1-S2 ... (4)
S1-B1-S2-B2 ... (5)
S1-B / S1-S2-B / S2 ... (6)
S1-B / S1-B / S2-S2 ... (7)
S1-B1-S2-B2-S3 ... (8)

In the above general formulas (1) to (8), S1, S2, and S3 each represent a polymer block (S) mainly composed of a vinyl aromatic monomer unit, and B, B1, and B2 are respectively. The polymer block (B) mainly composed of a conjugated diene monomer unit is shown, and B / S1 and B / S2 each contain 90% by mass of a vinyl aromatic monomer unit and a conjugated diene copolymer unit. Random copolymer blocks (B / S) less than or equal to are shown. )

The numbers assigned to S, B, and B / S in the general formulas (1) to (8) are the polymer block (S), the polymer block (B), and the random copolymer, respectively. It is a number for identifying a block (B / S), and those having different numbers may have the same or different molecular weight (polymerization degree) or copolymerization ratio of each block.

Further, the polymer block (S) and the polymer block (B) may each have a continuous continuous structure in which blocks having different components and compositions are formed. For example, the polymer block (B) may be B1-B2-B3 (B1, B2, and B3 are B blocks having different compositions or components). Further, the chain structure of the random copolymer block (B / S) may be a random block or a tapered block (a composition ratio gradually changed along the chain).

Further, the block copolymer a may be either a linear polymer or a branched polymer. Examples of the method for obtaining the branched polymer include a method in which the final ends of the polymerization are coupled by a coupling reaction, a method in which the terminal is branched from the initial stage of polymerization using a polyfunctional initiator, and the like.

Further, from the viewpoint of mechanical properties (particularly folding resistance) such as folding resistance of the resin sheet (for example, styrene resin sheet) of the present embodiment, the block copolymer a is a vinyl aromatic. It is preferable that the block copolymer has at least two or more polymer blocks S mainly composed of a hydrocarbon monomer unit.

(Peak molecular weight and molecular weight distribution of block copolymer a)
In the molecular weight distribution curve measured by the gel permeation chromatography measurement method (GPC measurement method), it is preferable that at least one peak molecular weight derived from the block copolymer a is present within the range of the molecular weight of 30,000 or more and 300,000 or less. .. As a result, the molding processability of the block copolymer composition tends to be further improved, and the mechanical properties of the resin sheet (for example, a styrene-based resin sheet) tend to be further improved. From the same viewpoint, the peak molecular weight derived from the block copolymer a is more preferably in the range of 40,000 or more and 250,000 or less, and further preferably in the range of 50,000 or more and 210000 or less. The peak molecular weight of the block copolymer a can be measured by the method described in Examples described later.

(Molecular weight distribution of block copolymer a (Mw / Mn))
The molecular weight distribution (Mw / Mn) of the block copolymer a is not particularly limited. By associating the polymerization active ends of a part of the polymer with a coupling agent or the like described later, a block copolymer a having a combination of different molecular weights can be obtained.

Furthermore, it is possible to stop the polymerization of some polymers by making the amount (number of moles) of alcohol such as ethanol added during the polymerization smaller than that of the additive (number of moles) of the polymerization initiator. As a result, block copolymer a, which is a mixture of different molecular weights, can be obtained. The molecular weight distribution (Mw / Mn) of the block copolymer a can be measured by the method described in Examples described later.

(Number average molecular weight (Mn) of polymer block S)
The number average molecular weight (Mn) of the polymer block S is preferably 10,000 to 60,000, more preferably 15,000 to 50,000, and even more preferably 20,000 to 40,000. When the number average molecular weight (Mn) of the polymer block S is within the above range, a resin sheet (for example, a styrene-based resin sheet) having more excellent mechanical properties and a good molded appearance can be obtained. .. The number average molecular weight (Mn) of the polymer block S in the block copolymer a can be controlled by adjusting the supply amount (feed amount) of the vinyl aromatic monomer to the polymerization initiator.

Further, in the present embodiment, when the block copolymer a has at least two or more polymer blocks S, the molecular weights of these polymer blocks S can be controlled independently. The number average molecular weight (Mn) of the polymer block S is the total number average molecular weight of all the polymer blocks S in the block copolymer a. For example, in the case of the block copolymer a having the S1-B / S1-S2 structure, the average molecular weight of the polymer block S is the number average molecular weight of S1 and S2 combined.

The number average molecular weight of the polymer block S in the block copolymer a is a method of oxidatively decomposing the block copolymer with tertiary butyl hydroperoxide using osmium tetroxide as a catalyst (IM KOLTHOFF, et al., J.). Polymer block S component (however, vinyl aromatic monomer polymer component having an average degree of polymerization of about 30 or less is excluded) obtained by the method described in Polym. Sci. 1,429 (1946). , Can be obtained by measurement using gel permeation chromatography (GPC). Specifically, it can be measured by the method described in Examples.

(Molecular weight distribution of polymer block (S) (Mw / Mn))
The molecular weight distribution (Mw / Mn) of the polymer block (S) is preferably 1.5 to 4.0, more preferably 1.6 to 3.6, and even more preferably 1.7 to 3. It is 2. When the molecular weight distribution (Mw / Mn) of the polymer block (S) is within the above range, the balance between the molding processability and the dispersibility between the block copolymer a and the copolymer b becomes even better. , There is a tendency to obtain a molded product having a good molded appearance without flow marks. The molecular weight distribution (Mw / Mn) of the polymer block S in the block copolymer a can be controlled by adjusting the supply amount (feed amount) of the vinyl aromatic monomer to the polymerization initiator.

Further, in the present embodiment, when the block copolymer a has at least two or more polymer blocks S, the molecular weight distribution of these polymer blocks S can be controlled independently. The molecular weight distribution (Mw / Mn) of the polymer block S is the total average molecular weight distribution of all the polymer blocks S in the block copolymer a. For example, in the case of the block copolymer a having the S1-B / S1-S2 structure, the average molecular weight of the polymer block S is the average molecular weight distribution of S1 and S2.

As another method for controlling the molecular weight distribution (Mw / Mn) of the polymer block S in the block copolymer a, for example, during the polymerization of the polymer block (S), a molar amount of ethanol smaller than that of the polymerization initiator is used. Examples thereof include a method of adding an alcohol such as the above to stop the polymerization of some polymers. This causes the polymer block S to have two peak molecular weights. It is also possible to control the molecular weight distribution of the polymer block S by obtaining the block copolymer a having the polymer blocks S having two or more different chain length distributions in this way.

Specifically, the molecular weight distribution of the polymer block S in the block copolymer a can be obtained by the method described in Examples described later.

(Method for producing block copolymer a)
As a method for producing the block copolymer a constituting the resin sheet (for example, a styrene-based resin sheet) of the present embodiment, a known technique can be used. An example of a typical conventional technique is a method of block-copolymerizing a conjugated diene monomer and a vinyl aromatic monomer in a hydrocarbon solvent using an anion initiator such as an organolithium compound. For example, in Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 57-49567, and Japanese Patent Publication No. 58-11446. It can be manufactured by the method described.

The block copolymer a can be obtained by polymerizing a vinyl aromatic monomer in a hydrocarbon solvent or, if necessary, copolymerizing a conjugated diene monomer. As the hydrocarbon solvent used for producing the block copolymer a, a conventionally known hydrocarbon solvent can be used, and the present invention is not limited to the following, but for example, n-butane, isobutane, n-pentane, n-hexane. , N-heptane, n-octane and other aliphatic hydrocarbons; cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, methylcycloheptane and other alicyclic hydrocarbons; and benzene, toluene, xylene. , Aromatic monomers such as ethylbenzene and the like. These hydrocarbon solvents may be used alone or in combination of two or more. Among these, when an organolithium initiator is used, n-hexane and cyclohexane are generally and preferably used.

The polymerization initiator is not particularly limited, and examples thereof include a polymerization initiator that exhibits anionic polymerization activity with respect to a conjugated diene monomer and a vinyl aromatic monomer, and specific examples thereof include an aliphatic hydrocarbon alkali metal. Examples thereof include alkali metal compounds such as compounds, aromatic monomer alkali metal compounds, and organic amino alkali metal compounds.

The alkali metal in the alkali metal compound is not particularly limited, and examples thereof include lithium, sodium, and potassium. The suitable alkali metal compound is not particularly limited, and is, for example, an aliphatic or aromatic lithium hydrocarbon compound having 1 to 20 carbon atoms, which contains one lithium in one molecule, or in one molecule. Examples thereof include dilithium compounds containing a plurality of lithiums, trilithium compounds, and tetralithium compounds. Such alkali metal compounds are not limited to the following, but specifically, n-propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, hexamethylenedilithium, and pig. Examples thereof include dienyldilithium, isoprenyldilithium, reaction products of diisopropenylbenzene and sec-butyllithium, and reaction products of divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene. ..

Further, the organic alkali metal compounds disclosed in the foreign patents shown in US Pat. No. 5,708,092, UK Patent No. 2241239, and US Pat. No. 5,527753 can also be used. These may be used alone or in combination of two or more. Among these, n-butyllithium is preferable.

The process for producing the block copolymer a is not particularly limited, but for example, a process in which an initiator is additionally added during the polymerization, an alcohol having a polymerization activity point lower than the polymerization active point, water, or the like is added during the polymerization, and then the monomer is supplied again. Then, the process of continuing the polymerization and the like can be mentioned. By appropriately selecting such a process, it is possible to prepare a block copolymer a in which a plurality of components having different molecular weights from each other are present.

Further, in the process of producing the block copolymer a, the vinyl fragrance of the block copolymer a finally obtained by adjusting the charging ratio of the vinyl aromatic monomer and the conjugated diene monomer which are the polymerization raw materials. The content of the group hydrocarbon monomer unit and the content of the conjugated diene monomer unit can be controlled.

As a method for producing a copolymer block composed of a vinyl aromatic monomer unit and a conjugated diene monomer unit, a mixture of a vinyl aromatic monomer and a conjugated diene monomer is continuously polymerized. Examples thereof include a method of supplying and polymerizing, a method of copolymerizing a vinyl aromatic monomer and a conjugated diene monomer using a polar compound or a randomizing agent, and the like.

The polar compound and the randomizing agent are not limited to the following, but for example, ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether; amines such as triethylamine and tetramethylethylenediamine; thioethers; phosphins; Phosphoramides; alkylbenzene sulfonates; alkoxides of potassium and sodium and the like.

The polymerization temperature in the polymerization step of the block copolymer a is generally in the range of −10 ° C. to 150 ° C., preferably 40 ° C. to 120 ° C. in the case of anionic polymerization using a polymerization initiator.
The time required for polymerization varies depending on the conditions, but is usually within 48 hours, preferably in the range of 1 hour to 10 hours. Further, it is preferable to replace the atmosphere of the polymerization system with an inert gas such as nitrogen gas. The polymerization pressure may be set within a range of sufficient pressure to maintain the monomer and the polymerization solvent in the liquid layer in the above polymerization temperature range, and is not particularly limited. Further, it is preferable to take care not to unintentionally mix impurities such as water, oxygen, carbon dioxide, etc. that inactivate the polymerization initiator and the living polymer into the polymerization system.

When the block copolymer a contains a random copolymer block, a mixture of a vinyl aromatic hydrocarbon monomer and a conjugated diene monomer is continuously supplied to a polymerization system for polymerization, and / or , A method such as copolymerizing a vinyl aromatic monomer and a conjugated diene monomer using a polar compound or a randomizing agent can be adopted.

When an organic alkali metal is used as a polymerization initiator in the production of the block polymer a which is a constituent component of the block copolymer composition of the present embodiment, when the polymerization reaction is stopped, two or more molecules are bonded and stopped. The coupling reaction that causes the reaction can be suitably used. In the coupling reaction, the coupling agent exemplified below can be added into the polymerization system. In addition, by adjusting the amount of the coupling agent added, only a part of the polymers in the polymerization system are coupled, and by coexisting the uncoupled polymer and the coupling polymer, two or more peaks in the molecular weight distribution. It is also possible to produce a block copolymer a having the above.

The coupling agent that can be suitably used for producing the block polymer a constituting the block copolymer composition of the present embodiment is not particularly limited, and examples thereof include any coupling agent having two or more functionalities. Specifically, tetraglycidylmethoxylenidamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-p-phenylenediamine, tetraglycidyldiaminodiphenylmethane, diglycidylaniline, diglycidyl orthotoluidine, γ-glycidoxy. Ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxy Examples thereof include silane compounds containing an amino group such as propyltributoxysilane. Examples of other coupling agents include 1- [3- (triethoxysilyl) -propyl] -4-methylpiperazine and 1- [3- (diethoxyethylsilyl) -propyl] -4-methylpiperazine. , 1- [3- (trimethoxysilyl) -propyl] -3-methylimidazolidine, 1- [3- (diethoxyethylsilyl) -propyl] -3-ethylimidazolidine, 1- [3- (triethoxy) Cyril) -propyl] -3-methylhexahydropyrimidine, 1- [3- (dimethoxymethylsilyl) -propyl] -3-methylhexahydropyrimidine, 3- [3- (tributoxysilyl) -propyl] -1- Methyl-1,2,3,4-tetrahydropyrimidine, 3- [3- (dimethoxymethylsilyl) -propyl] -1-ethyl-1,2,3,4-tetrahydropyrimidine, 1- (2-ethoxyethyl) -3- [3- (Trimethoxysilyl) -propyl] -imidazolidine, (2- {3- [3- (trimethoxysilyl) -propyl] -tetrahydropyrimidine-1-yl} -ethyl) dimethylamine, etc. Examples thereof include a silane compound containing a silyl group. Examples of other coupling agents include γ-glycidoxypropyltriphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylethyldimethoxysilane, and γ-glycidoxypropylethyldi. Ethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldipropoxysilane, γ-glycidoxypropylmethyldibutoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ-gly Sidoxypropyldimethylmethoxysilane, γ-glycidoxypropyldiethylethoxysilane, γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropyldimethylphenoxysilane γ-glycidoxypropyldiethylmethoxysilane, γ-glycid Xipropylmethyldiisopropeneoxysilane, bis (γ-glycidoxypropyl) dimethoxysilane, bis (γ-glycidoxypropyl) diethoxysilane, bis (γ-glycidoxypropyl) dipropoxysilane, bis (γ) -Glysidoxypropyl) dibutoxysilane, bis (γ-glycidoxypropyl) diphenoxysilane, bis (γ-glycidoxypropyl) methylmethoxysilane, bis (γ-glycidoxypropyl) methylethoxysilane, bis (Γ-Glysidoxypropyl) Methylpropoxysilane, bis (γ-glycidoxypropyl) methylbutoxysilane, bis (γ-glycidoxypropyl) methylphenoxysilanetris (γ-glycidoxypropyl) methoxysilane, etc. Examples thereof include a silane compound containing a glycidoxy group. Examples of other coupling agents include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-methacryloxyethyltriethoxysilane, and bis (. Examples thereof include silane compounds containing a methacryloxy group such as γ-methacryloxypropyl) dimethoxysilane and tris (γ-methacryloxypropyl) methoxysilane. Examples of other coupling agents include β- (3,4-epoxycyclohexyl) ethyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triethoxysilane, and β- (3,4). -Epoxycyclohexyl) Ethyl-tripropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-tributoxysilane, β- (3,4-epoxycyclohexyl) ethyl-triphenoxysilane β- (3,4-epoxycyclohexyl) ) Propyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-ethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyl -Ethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldipropoxysilane, β- (3,4-epoxycyclohexyl) Ethyl-Methyldibutoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylmethoxysilane, β- (3,4-epoxycyclohexyl) Ethyl-diethylethoxysilane β- (3,4-epoxycyclohexyl) ethyl-dimethylethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylpropoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethyl Butoxysilane, β- (3,4-epoxycyclohexyl) ethyl-dimethylphenoxysilane, β- (3,4-epoxycyclohexyl) ethyl-diethylmethoxysilane, β- (3,4-epoxycyclohexyl) ethyl-methyldiisopro Examples thereof include silane compounds containing an epoxycyclohexyl group such as penoxysilane. Examples of other coupling agents include 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N, N'-dimethylpropylene urea, and N-methylpyrrolidone.

When the coupling agent is added to the living end of the block copolymer a, the structure of the living end of the block copolymer a is not limited, but the block copolymer composition of the present embodiment is not limited. From the viewpoint of mechanical strength and the like, it is preferable that the living end of the block mainly contains a vinyl aromatic hydrocarbon monomer. The amount of the coupling agent used is preferably 0.1 equivalent or more and 10 equivalents or less, and more preferably 0.5 equivalent or more and 4 equivalents or less, with respect to 1 equivalent of the living end of the block copolymer a. The coupling agent may be used alone or in combination of two or more.

(Copolymer b)
The copolymer b is a vinyl aromatic hydrocarbon monomer unit (a unit derived from a vinyl aromatic hydrocarbon monomer) and a (meth) acrylic acid and / or a (meth) acrylic acid alkyl ester monomer unit. It is a random copolymer with (a unit derived from (meth) acrylic acid and / or (meth) acrylic acid alkyl ester monomer), and is a vinyl aromatic hydrocarbon monomer unit, (meth) acrylic acid and / Or may contain other polymerizable monomer units other than the (meth) acrylic acid alkyl ester monomer unit, if necessary.

The vinyl aromatic monomer is not particularly limited as long as it has an aromatic ring and a vinyl group in the molecule, and for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, etc. p-ethylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 1,3-dimethylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene, vinylanthracene, 1,1- Examples include diphenylethylene. These vinyl aromatic monomers may be used alone or in combination of two or more. Among these, styrene is preferable.

The (meth) acrylic acid and / or (meth) acrylic acid ester monomer means one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid alkyl ester, and methacrylic acid alkyl ester. do. The alkyl ester may be one or more of an ester compound of an alkyl alcohol having 1 to 8 carbon atoms (C1 to C8) and acrylic acid and / or methacrylic acid. Specific examples of the (meth) acrylic acid and / or (meth) acrylic acid ester monomer include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, and n-butyl acrylate (butyl). Acrylic acid C _1-6 alkyl ester such as acrylate), n-pentyl acrylate, n-hexyl acrylate, cycloalkyl ester of acrylate such as cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid. Examples thereof include methacrylic acid C _1-6 alkyl esters such as n-butyl, n-pentyl methacrylate and n-hexyl methacrylate, and cyclohexyl methacrylate esters such as cyclohexyl methacrylate. Among these, softening of the copolymer b Acrylic acid C _1-6 alkyl ester and methacrylic acid C _1-6 alkyl ester are preferable from the viewpoint that the temperature can be further increased and as a result, the moldability and heat-resistant deformability of the obtained resin sheet can be further improved. Acrylic acid C _1-4 alkyl ester and methacrylic acid C _1-4 alkyl ester are more preferable, and methyl acrylate and / or methyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.

The copolymer b of the present embodiment is within a range that does not impair the action and effect of the present invention (particularly, improvement of transparency due to adjusting the refractive index of copolymer b described later and improvement of VICAT softening temperature). In addition to the vinyl aromatic hydrocarbon monomer unit and the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit, other copolymerizable monomer units (hereinafter, simply "others"). Also referred to as "monomer unit of"). As described above, the content of the other monomer unit in the copolymer b (100% by mass) is not particularly limited as long as it does not inhibit the action and effect of the present invention, but is, for example, 2% by mass or less. Is.

The mass ratio of the vinyl aromatic hydrocarbon monomer unit in the copolymer b to the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit is the former / the latter = 50/50 or more. It is 90/10, preferably 60/40 to 90/10, and more preferably 70/30 to 85/15. When the mass ratio is within the above range, a block copolymer composition having low hygroscopicity and excellent mechanical properties can be obtained. On the other hand, when the content of the vinyl aromatic hydrocarbon monomer unit is less than 50% by mass, the moisture absorption property becomes strong, pre-drying before molding is required, and the block copolymer a and the copolymer b are required. The compatibility with the block copolymer composition is lowered, and the mechanical properties of the block copolymer composition are lowered. Further, when the content of the vinyl aromatic hydrocarbon monomer unit exceeds 90% by mass, the mechanical properties (particularly the folding resistance) are deteriorated.

The copolymer b can be produced by polymerizing by a known method. For example, it can be produced by using known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization. In the coexistence of a vinyl aromatic hydrocarbon monomer with (meth) acrylic acid and / or (meth) acrylic acid ester, a production method by radical polymerization is industrially common. In the method for producing the copolymer b, a polymerization initiator such as an organic peroxide may be used, or thermal polymerization may be performed without using an initiator. Further, from the viewpoint of controlling the polymerization reaction, a chain transfer agent such as a polymerization solvent or an aliphatic mercaptan can be used if necessary.

The polymerization solvent is used to keep the viscosity in the reaction system low in the continuous polymerization process, and examples of the organic solvent include alkylbenzenes such as benzene, toluene, ethylbenzene and xylene, and ketones such as acetone and methyl ethyl ketone. An aliphatic hydrocarbon such as hexane or cyclohexane can be used.

In particular, when a polyfunctional vinyl aromatic hydrocarbon monomer is used, it is preferable to use a polymerization solvent from the viewpoint of suppressing gelation. By using a polymerization solvent, it becomes difficult to form a gel, a high degree of control in the polymerization process becomes possible, and it becomes easier to obtain a copolymer b having a desired composition and physical properties.

The amount of the polymerization solvent used is not particularly limited in this embodiment, but is usually 1 to 50% by mass with respect to the entire composition in the polymerization reactor from the viewpoint of controlling gelation. It is preferably in the range of 5 to 25% by mass, and more preferably in the range of 5 to 25% by mass. When the amount of the polymerization solvent used is 50% by mass or less, it tends to be possible to obtain a copolymer b excellent in suppression of gelation, ease of control in the polymerization process, and productivity.

At the time of producing the copolymer b of the present embodiment, a polymerization initiator such as an organic peroxide can be preferably used. Examples of the polymerization initiator include 1,1-di (t-butylperoxy) cyclohexane, 2,2-di (t-butylperoxy) butane, and 2,2-di (4,4-di-t-). Peroxyketals such as butylperoxycyclohexyl) propane, 1,1-di (t-amylperoxy) cyclohexane; hydroperoxides such as cumenehydroperoxide, t-butylhydroperoxide; t-butylperoxy Alkyl peroxides such as acetate and t-amylperoxyisononanoate; dialkyl peroxides such as t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide and di-t-hexyl peroxide. Peroxyesters such as t-butylperoxyacetate, t-butylperoxybenzoate, t-butylperoxyisopropyl monocarbonate; t-butylperoxyisopropylcarbonate, polyethertetrakis (t-butylperoxycarbonate), etc. Peroxycarbonates; N, N'-azobis (cyclohexane-1-carbonitrile), N, N'-azobis (2-methylbutyronitrile), N, N'-azobis (2,4-dimethylvaleronitrile) ), N, N'-azobis [2- (hydroxymethyl) propionitrile] and the like. These polymerization initiators may be used alone or in combination of two or more.

Further, in the polymerization process of block copolymer b, a chain transfer agent can be used for the purpose of adjusting its molecular weight, and examples of the chain transfer agent include aliphatic mercaptan, aromatic mercaptan, pentaphenylethane, and α-methylstyrene. Examples include polymers and terpinolene.

The weight average molecular weight (Mw) of the copolymer b is generally in the range of 80,000 to 400,000, which is preferable. When the copolymer b is in the range of this weight average molecular weight, a block copolymer composition having a good balance between mechanical properties and molding processability can be obtained. When the weight average molecular weight is 80,000 or more, the fluidity tends to be further suppressed, the brittleness is less likely to occur, and cracks and the like are less likely to occur during processing. On the other hand, when the weight average molecular weight is 400,000 or less, sufficient fluidity can be ensured and the molding processability tends to be further improved.

The copolymer b contains a styrene monomer unit and acrylic acid C ₁ from the viewpoint that the softening temperature of the copolymer b can be further increased and, as a result, the moldability and heat-resistant deformability of the obtained resin sheet can be further improved. _-4 Copolymer with alkyl ester monomer unit and / or methacrylic acid C _1-4 alkyl ester monomer unit (eg, styrene-methyl methacrylate copolymer (MS resin), styrene-methyl acrylate- Methyl methacrylate copolymer and styrene-butyl acrylate copolymer) are preferable.

In particular, when it is used as a packaging material for electronic parts, it is preferably good in heat resistance and deformability, and from this viewpoint, a styrene-methyl methacrylate copolymer (MS resin) is preferable. On the other hand, from the viewpoint of excellent transparency and folding resistance, a styrene-butyl acrylate copolymer is preferable. As the MS resin, a commercially available product may be used, and examples thereof include the product "Estyrene (registered trademark) MS" of Nippon Steel & Sumikin Chemical Co., Ltd.

(Other additives that can be added to the block copolymer composition)
The block copolymer composition of the present embodiment may contain any additive as long as it does not interfere with the action and effect of the present embodiment. Examples of the additive include those generally used for blending resins and rubber-like polymers, for example, inorganic fillers such as calcium carbonate, magnesium carbonate and silica, fatty acids such as stearic acid and behenic acid, and stearic acid. Fatty metal salts such as zinc, calcium stearate, magnesium stearate, lubricants and mold release agents such as fatty acid amide such as ethylene bisstearylamide, softeners and plasticizers such as paraffin oil, process oil, organic polysiloxane, mineral oil, hinder Reinforcing agents for dophenol-based, phosphorus-based heat stabilizers and antioxidants, hindered amine-based light stabilizers, benzotriazole-based ultraviolet absorbers, flame retardants, antistatic agents, organic fibers, glass fibers, carbon fibers, metal whiskers, etc. , Organic pigments, inorganic pigments, colorants such as organic dyes and the like are exemplified.

[Manufacturing method of resin sheet of this embodiment]
The method for producing the resin sheet (for example, a styrene-based resin sheet) of the present embodiment is not particularly limited. , Cylindrical shape, etc.) is generally extruded and molded. In addition, a resin composition prepared using a mixer such as a kneader, a Banbury mixer, a roll, a ribbon blender, a Henshell mixer, a single-screw or twin-screw extruder, or a kneader is used as a die (flat, T, cylindrical, etc.). ) May be used for molding. The resin sheet of the present embodiment (for example, a styrene-based resin sheet) may be uniaxially stretched or biaxially stretched, but is usually a non-stretched sheet or a low-stretched sheet having a take-up action in the extrusion direction. More preferably, it is a non-stretched sheet or a low-stretched sheet on the extrusion direction side manufactured by using a T-die extruder equipped with an embracing main roll and a touch roll.

The thickness of the resin sheet (for example, a styrene-based resin sheet) of the present embodiment is not particularly limited, but is preferably 10 μm to 4 mm, more preferably 50 μm to 2.0 mm, still more preferably 0.1 mm to 1.5 mm, and further. More preferably, it is 0.2 mm to 1.0 mm.

The resin sheet of the present embodiment (for example, a styrene-based resin sheet) may be a single layer or a multilayer. In the case of multiple layers, the resin composition of each layer may be the same or different. When the resin composition of each layer is different, it is sufficient that at least one of the layers constituting the plurality of layers contains a layer made of the block copolymer composition of the present invention, and even the front and back layers are internal intermediate layers. But it may be. Further, for the purpose of in-process recycling, at least one layer of the intermediate layer may be blended with the scraps of the sheet. In that case, the new material and the recycled material may be blended in an arbitrary ratio or the recycled material may be used alone. The recycled material is preferably generated from the same line, but different resin compositions generated in other series may be blended as long as the action and effect of the present invention are not impaired.

Further, the surface of the resin sheet (for example, a styrene-based resin sheet) or the packaging material for electronic parts of the present embodiment may be surface-treated (for example, discharge treatment such as corona discharge or glow discharge, acid treatment, etc.). Since the surface of the resin sheet (for example, a styrene resin sheet) or the packaging material for electronic parts of the present embodiment has excellent printability, a conductive film or an antistatic layer (for example, a film with conductive ink) is formed. You may.

[Fold resistance]
The resin sheet of the present embodiment (for example, a styrene-based resin sheet) preferably has a folding resistance of 500 times or more in both the MD direction and the TD direction, which is measured in accordance with JIS P8115. More specifically, in the MIT fold resistance tester under a spring load of 9.8 N, the number of fold resistance until the test piece breaks is 100 times or more in either the MD direction or the TD direction. For example, it can be said that it has sufficient rigidity, but the folding resistance is preferably 500 times or more. In particular, carrier tape, which is a typical form of packaging material for electronic parts, is a long packaging material for electronic parts and is used not only for storage and transportation but also for mounting on assembly equipment. It is required that it does not break easily even when it is bent. This characteristic can be evaluated by the number of fold resistance until breaking using the MIT fold resistance tester specified in JIS P8115: 2001. More preferably, the folding resistance is 1000 times or more in the extrusion direction (MD) and 500 times or more in the extrusion vertical direction (TD), and more preferably the folding resistance is 1000 times or more in the extrusion direction (MD) and the extrusion vertical direction (MD). Both of TD) are 1000 times or more, and most preferably, the folding resistance is 2000 times or more in both the extrusion direction (MD) and the extrusion vertical direction (TD).

The folding resistance of a conventional general resin sheet (for example, a styrene-based resin sheet) depends on the thickness of the sheet, and the thinner the sheet, the lower the stress during bending, so the folding resistance tends to improve. .. However, the resin sheet of the present embodiment (for example, a styrene-based resin sheet) is a milky white half that is conventionally used and is composed of a composition of a block copolymer and general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS). Compared to transparent sheets, the thickness dependence of fold resistance is relatively small, the range of thickness that expresses 100 times or more is considerably wider than that of conventional sheets, and even relatively thick sheets of 0.5 mm or more are fold resistant. It is easy to develop strength 100 times or more.

[Internal haze value]
The resin sheet of the present embodiment (for example, a styrene resin sheet) has an internal haze value of 4.0% or less (for example, 0% or more and 4.0% or less) measured in accordance with ISO 14782, and is 3.5. % Or less, more preferably 3.0% or less, further preferably 2.5% or less, and particularly preferably 2.0% or less. The haze value is the ratio of the diffuse transmittance to the total light transmittance (unit:%), and the smaller the value, the higher the transparency. A completely transparent object has a haze value of zero. In order to reduce the internal haze value, it can be achieved by making the difference in refractive index between the block copolymer a and the copolymer b as close to zero as possible. The absolute value of the preferable refraction difference is 0.004 or less, the absolute value of the more preferable refraction difference is 0.003 or less, and the absolute value of the more preferable refraction difference is 0.002 or less, which is the most preferable refraction. The absolute value of the rate difference is 0.001 or less. By setting the absolute value of the refractive index difference to the above value or less, the internal haze value of the resin sheet (for example, a styrene-based resin sheet) of the present embodiment can be set to 2.0% or less. The refractive index of each block copolymer a and copolymer b tends to be uniquely determined by the type of each monomer unit and the content of the monomer unit. For example, in the case of the copolymer b, the polymer having a vinyl aromatic hydrocarbon monomer unit content of 100% by mass has the highest refractive index, and the vinyl aromatic hydrocarbon monomer unit and (meth ) The refractive acid can be reduced by increasing the content of the latter relative to the sum of the acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit. In this way, the refractive index of the block copolymer a can be adjusted by controlling the mass ratio of the vinyl aromatic hydrocarbon monomer unit of the block copolymer a and the conjugated diene monomer unit. By controlling the mass ratio of the vinyl aromatic hydrocarbon monomer unit of the block copolymer b to the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit, the copolymer b is controlled. The refractive index of each block copolymer a and the copolymer b can be adjusted as appropriate, so that the difference in refractive index can be brought close to zero.

Further, the refractive indexes of the block copolymer a and the copolymer b can be easily measured by an Abbe type refractive index meter. Specifically, a film having a block copolymer a component and a copolymer b component having a thickness of about 0.2 mm is produced using a compression molding machine, and the film is formed in an environment of a temperature of 23 ° C. and a humidity of 50% 24. After a lapse of time, the refractive index can be measured using an Abbe refractometer manufactured by Atago Co., Ltd. at a measurement light wavelength of 589 nm in accordance with JIS K7142: 2008 "Plastic-How to determine the refractive index".

Further, the internal haze refers to the haze value of the composition itself of the resin sheet (for example, the styrene-based resin sheet) excluding the shape factors such as the unevenness of the surface of the resin sheet (for example, the styrene-based resin sheet). By setting the internal haze value to 4.0% or less, the resin sheet of the present invention (for example, a styrene resin sheet) has excellent transparency, and particularly excellent visibility and easy inspection of the contents. Packaging materials for electronic parts can be obtained. The method for measuring the internal haze is not limited, but for example, a resin sheet (for example, a styrene resin sheet) is cut to an appropriate size and gently immersed in an optical quartz cell filled with liquid paraffin so as to prevent air bubbles. It can be measured with a haze measuring device.

[Heat-resistant deformability]
The resin sheet of the present embodiment (for example, a styrene-based resin sheet) is heated again, for example, and molded into an electronic component packaging material such as a carrier tape. At that time, it is desirable to have a certain degree of heat-resistant deformability because it is molded under a certain tension and it is assumed that it may be transported or stored in a high temperature environment. The heat-resistant deformability can be evaluated at the VICAT softening temperature specified by ISO306. The measurement conditions are a load of 10 N and a heating rate of 50 ° C./min. Since the sample shape cannot be measured with the sheet as it is, heat press molding is performed again to prepare a test piece having a thickness of 4 mm. For carrier tape applications, the VICAT softening temperature is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, further preferably 75 ° C. or higher, and even more preferably 80 ° C. or higher. It is more preferably 85 ° C. or higher, and particularly preferably 90 ° C. or higher. By using a resin sheet having VICAT softening of 60 ° C. or higher (for example, a styrene-based resin sheet), it has good moldability and is excellent in quality as a packaging material for electronic parts.

[Packaging materials for electronic components]
The packaging material for electronic parts of the present embodiment can be obtained by further molding the resin sheet of the present embodiment (for example, a styrene-based resin sheet). The molding method for obtaining the packaging material for electronic parts from the resin sheet (for example, a styrene-based resin sheet) is not limited in any way, and a known molding method can be adopted. As a molding method for obtaining a packaging material for electronic parts, for example, in addition to vacuum forming, pressure forming, blow forming, bending, match molding, etc., plug assist forming, air slip forming, hot plate pressure forming, vacuum pressing, etc. A known heat molding method such as molding can be mentioned and can be preferably used.

The packaging material for electronic parts is a resin product for packaging various electronic parts, and is a resin packaging material for packaging semiconductors, integrated circuits (ICs), capacitors, and the like. For that purpose, in addition to storage and transportation, the mainstream is that the packaging material can be mounted on the assembly device as it is. In addition to tray-shaped packaging materials, tape-shaped packaging materials are often used, and can be particularly preferably used for "carrier tapes" wound on resin reels. The carrier tape wound on a resin reel is widely used as a packaging material that can be directly mounted on an assembly device. As a characteristic required for the carrier tape, depending on the contents, transparency that the contents can be visually recognized or the contents can be inspected may be required. In addition, carrier tape is a very long packaging material for electronic parts, and breaking due to unexpected troubles during mounting causes major problems in automatic production and mass production by mechanization, so it is easy. A high degree of folding resistance that does not break is strongly required.

Hereinafter, the present invention will be described with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

First, block copolymer a and copolymer b were produced, various resin sheets having different thicknesses were prepared using these raw materials, and test pieces were cut out from the resin sheets to evaluate various physical properties.

As shown below, block copolymers a1 to a7 were produced (Production Examples 1 to 7).

(Manufacturing Example 1)
Under a nitrogen gas atmosphere, 0.08 parts by mass of n-butyllithium and 0.015 parts by mass of tetramethylmethylenediamine were added to a cyclohexane solution containing 20 parts by mass of styrene at a concentration of 25% by mass, and the temperature was 80 ° C. Polymerized in 20 minutes. Then, a cyclohexane solution containing 8 parts by mass of 1,3-butadiene at a concentration of 25% by mass was added to the obtained polymerization solution at a time, and the mixture was polymerized at 80 ° C. for 15 minutes. Next, a cyclohexane solution containing 9 parts by mass of 1,3-butadiene and 15 parts by mass of styrene at a concentration of 25% by mass was continuously added to the polymerization solution over 30 minutes and polymerized at 80 ° C. Next, a cyclohexane solution containing 8 parts by mass of 1,3-butadiene at a concentration of 25% by mass was added to the polymerization solution at a time, and the mixture was polymerized at 80 ° C. for 15 minutes. Next, a cyclohexane solution containing 3 parts by mass of styrene at a concentration of 25% by mass was added to the polymerization solution, and the mixture was polymerized at 80 ° C. for 5 minutes. Next, ethanol was added to the polymerization solution in a molar amount of 0.4 times the amount of n-butyllithium, and the mixture was held for 5 minutes. Next, a cyclohexane solution containing 37 parts by mass of styrene at a concentration of 25% by mass was added to the polymerization solution, and the mixture was polymerized at 80 ° C. for 25 minutes.

Then, in order to completely stop the polymerization, ethanol was added to the reactor in an amount of 0.6 mol times the amount of n-butyllithium added, and 2 as a heat stabilizer with respect to 100 parts by mass of the block copolymer. Block copolymer a1 by adding 0.3 parts by mass of -t-butyl-6 (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate and then removing the solvent. Was recovered.

(Manufacturing Example 2)
Under a nitrogen gas atmosphere, 0.08 parts by mass of n-butyllithium and 0.015 parts by mass of tetramethylmethylenediamine were added to a cyclohexane solution containing 20 parts by mass of styrene at a concentration of 25% by mass, and 20 parts by mass was added at 80 ° C. Polymerization was carried out for a minute (step 1). Next, a cyclohexane solution containing 14 parts by mass of 1,3-butadiene and 10 parts by mass of styrene at a concentration of 25% by mass was continuously added to the polymerization solution over 30 minutes and polymerized at 80 ° C. (step 2). .. Next, a cyclohexane solution containing 16 parts by mass of 1,3-butadiene and 10 parts by mass of styrene at a concentration of 25% by mass was continuously added to the polymerization solution over 30 minutes and polymerized at 80 ° C. (step 3). .. Next, a cyclohexane solution containing 30 parts by mass of styrene at a concentration of 25% by mass was added to the polymerization solution, and the mixture was polymerized at 80 ° C. for 30 minutes (step 4).

After that, in order to completely stop the polymerization, ethanol was added in the same volume to n-butyllithium in the reactor, and 2-t-butyl- as a heat stabilizer was added to 100 parts by mass of the block copolymer. Block copolymer a2 was recovered by adding 0.3 parts by mass of 6 (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate and then removing the solvent.

(Block Copolymer a3)
In step 1, 20 parts by mass of styrene was replaced with 31 parts by mass of styrene, and in step 2, 14 parts by mass of 1,3-butadiene and 10 parts by mass of styrene were replaced with 21 parts by mass of 1,3-butadiene and 21 parts by mass. 20 parts by mass of styrene, 2 parts by mass of 1,3-butadiene and 6 parts by mass of styrene in place of 16 parts by mass of 1,3-butadiene and 10 parts by mass of styrene in step 3, in step 4. The block copolymer a3 was recovered in the same manner as in Production Example 2 except that 20 parts by mass of styrene was used instead of 30 parts by mass of styrene.

(Manufacturing Example 4)
Under a nitrogen gas atmosphere, 0.08 parts by mass of n-butyllithium and 0.015 parts by mass of tetramethylmethylenediamine were added to a cyclohexane solution containing 15 parts by mass of styrene at a concentration of 25% by mass, and 20 parts at 80 ° C. Polymerization was carried out for a minute (step 1). Next, a cyclohexane solution containing 38 parts by mass of 1,3-butadiene and 10 parts by mass of styrene at a concentration of 25% by mass was continuously added to the polymerization solution over 30 minutes and polymerized at 80 ° C. (step 2). .. Next, a cyclohexane solution containing 37 parts by mass of styrene at a concentration of 25% by mass was added to the polymerization solution, and the mixture was polymerized at 80 ° C. for 30 minutes (step 3).

After that, in order to completely stop the polymerization, ethanol was added in the same volume to n-butyllithium in the reactor, and 2-t-butyl- as a heat stabilizer was added to 100 parts by mass of the block copolymer. Block copolymer a4 was recovered by adding 0.3 parts by mass of 6 (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate and then removing the solvent.

(Manufacturing Example 5)
Same as Production Example 2 except that in step 1, 20 parts by mass of styrene was replaced with 26 parts by mass of styrene, and in step 4, 30 parts by mass of styrene was replaced with 24 parts by mass of styrene. The block copolymer a5 was recovered.

(Manufacturing Example 6)
Under a nitrogen gas atmosphere, 0.08 parts by mass of n-butyllithium and 0.015 parts by mass of tetramethylmethylenediamine were added to a cyclohexane solution containing 60 parts by mass of styrene at a concentration of 25% by mass, and 20 parts at 80 ° C. Polymerized for minutes. Next, a cyclohexane solution containing 30 parts by mass of 1,3-butadiene and 10 parts by mass of styrene at a concentration of 25% by mass was continuously added to the polymerization solution over 30 minutes and polymerized at 80 ° C.

After that, in order to completely stop the polymerization, ethanol was added in the same volume to n-butyllithium in the reactor, and 2-t-butyl- as a heat stabilizer was added to 100 parts by mass of the block copolymer. Block copolymer a6 was recovered by adding 0.3 parts by mass of 6 (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate and then removing the solvent.

(Manufacturing Example 7)
In step 1, 15 parts by mass of styrene was replaced with 17 parts by mass of styrene, and in step 2, 38 parts by mass of 1,3-butadiene and 10 parts by mass of styrene were replaced with 60 parts by mass of 1,3-butadiene and 60 parts by mass. The block copolymer a7 was recovered in the same manner as in Production Example 4, except that 7 parts by mass of styrene was used and 16 parts by mass of styrene was used instead of 37 parts by mass of styrene in step 3.

Table 1 shows various characteristics of the block copolymers a1 to a7 obtained in each of Production Examples 1 to 7.

The structures of the block copolymers a1 to a7 shown in Table 1 were measured according to the following methods.

<Content of vinyl aromatic monomer unit (styrene unit) of each block copolymer a1 to a7>
The content of the vinyl aromatic monomer unit of each block copolymer a1 to a7 was measured by a UV meter (ultraviolet absorptiometer). Specifically, about 30 mg (accurately weighed up to 0.1 mg unit) of each block copolymer a1 to a7 is dissolved in 100 mL of chloroform, the polymer solution is filled in a quartz cell and set in an analyzer, and ultraviolet rays are applied thereto. The wavelength of 260 to 290 nm was scanned, and the value of the obtained absorption peak height was determined by the calibration curve method. When the vinyl aromatic monomer is styrene, the peak wavelength appears at 269.2 nm.

<Content of conjugated diene monomer unit (butadiene unit) of each block copolymer a1 to a7>
The content of the conjugated diene monomer unit (butadiene unit) of each block copolymer a1 to a7 is calculated by subtracting from 100% by mass based on the mass% of the vinyl aromatic monomer unit obtained above. did.

<Weight average molecular weight Mw, number average molecular weight Mn, molecular weight distribution Mw / Mn, peak molecular weight, and number of molecular weight peaks of each block copolymer a1 to a7>
The weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn), peak molecular weight, and number of molecular weight peaks of each block copolymer a1 to a7 are determined by gel permeation chromatography (GPC). It was measured by the device under the following measurement conditions.

(Measurement condition)
GPC device: HLC-8220 manufactured by Tosoh Corporation
Column: Two SuperMultipore HZ-M manufactured by Tosoh Co., Ltd. are connected in series. Column temperature: 40 ° C.
Liquid delivery volume: 0.2 mL / min Detector: Refractometer (RI)

Tetrahydrofuran was used as a solvent, and about 10 mg of the polymer for molecular weight measurement was dissolved in 20 mL of tetrahydrofuran and filtered to remove insoluble components to obtain a sample for GPC measurement.

The specific measurement method is described below. First, a calibration curve was prepared using 9 standard polystyrene samples having different molecular weights and known molecular weights. The weight average molecular weight (Mw) of the lowest molecular weight standard polystyrene was 1090000, and the lowest molecular weight was 1050. Subsequently, the measurement sample was prepared in the same manner as described above using the block polymer (a) for measuring the molecular weight.

After confirming that the temperature inside the tank containing the column became constant, a solution sample was injected and measurement was started. After the measurement was completed, the obtained molecular weight distribution curve was statistically processed, and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated. The molecular weight distribution (Mw / Mn) was defined as a value obtained by dividing the obtained weight average molecular weight (Mw) by the number average molecular weight (Mn). The peak molecular weight and the number of molecular weight peaks were determined from the above molecular weight distribution curve.

<Weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polymer blocks (S) of the block copolymers a1 to a7>.
Next, the molecular weight of the polymer blocks (S) constituting the block copolymers a1 to a7 was measured. Specifically, after dissolving about 20 mg of the polymer in about 10 mL of chloroform, 20 mL of an osmium acid solution is added and the mixture is boiled in hot water for 30 minutes to decompose the conjugated diene moiety. Approximately 200 mL of methanol was gently poured into the decomposed polymer solution to precipitate insoluble components in the solvent. The precipitated component is the polymer block (S), and the styrene monomer not forming the block and the styrene having a low degree of polymerization remain dissolved in the methanol / tertiary butyl alcohol / chloroform mixed solution. After filtering this precipitate, it was washed with pure methanol and vacuum dried to obtain a polymer block (S).

Here, the above-mentioned osmium acid solution is 1 g of osmium oxide (VIII) and 2 kg of the trade name "Perbutyl H (chemical name: tert-butyl hydroperoxide, purity 69%)" marketed and available from Nichiyu Co., Ltd. Is a solution in which 3 L of tert-butyl alcohol is dissolved and mixed.

About 10 mg of the polymer block (S) thus obtained was dissolved again in 20 mL of tetrahydrofuran and measured by a GPC apparatus. The measurement conditions and methods were carried out according to the measurement conditions and methods for the molecular weight of the block copolymer a.

<Melt flow rate of block copolymer a>
The measurement was performed under the conditions of a temperature of 200 ° C. and a load of 5 kgf in accordance with the standard ISO1133.

Next, the copolymers b1 to b6 were synthesized as shown below (Production Examples 8 to 13).

(Manufacturing Example 8)
Under a nitrogen gas atmosphere, 69.7 parts by mass of styrene, 15.3 parts by mass of butyl acrylate, 15 parts by mass of ethylbenzene, and 1,1-bis (t-butylperoxy) cyclohexane (trade name Perhexa C manufactured by Nichiyu Co., Ltd.) ) 0.02 parts by mass was mixed to prepare a raw material composition liquid, charged in a reactor, and continuous bulk polymerization was performed at a reaction temperature of 120 ° C. Then, 0.2 parts by mass of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (trade name: Irganox 1076 manufactured by BASF Japan) was added as an antioxidant, and then the solvent was not added. The copolymer b1 was recovered by removing the reaction monomer.

(Manufacturing Example 9)
In a nitrogen gas atmosphere, 68.0 parts by mass of styrene, 17.0 parts by mass of methyl methacrylate, 15 parts by mass of ethylbenzene, and 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (daily). Oil Co., Ltd. Product name Pertetra A) 0.02 parts by mass was mixed to prepare a raw material composition liquid, charged in a reactor, and subjected to continuous bulk polymerization at a reaction temperature of 120 ° C. Then, 0.2 parts by mass of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid as an antioxidant was added, and then the solvent and the unreacted monomer were removed to remove the copolymer. b2 was recovered.

(Manufacturing Example 10)
Under a nitrogen gas atmosphere, 59.5 parts by mass of styrene, 25.5 parts by mass of methyl methacrylate, 15 parts by mass of ethylbenzene, and 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane 0. 02 parts by mass were mixed to prepare a raw material composition liquid, which was charged into a reactor and subjected to continuous bulk polymerization at a reaction temperature of 120 ° C. Then, 0.2 parts by mass of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid as an antioxidant was added, and then the solvent and the unreacted monomer were removed to remove the copolymer. b3 was recovered.

(Manufacturing Example 11)
Under a nitrogen gas atmosphere, 34.0 parts by mass of styrene, 51.0 parts by mass of methyl methacrylate, 15 parts by mass of ethylbenzene, and 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane 0. 02 parts by mass were mixed to prepare a raw material composition liquid, which was charged into a reactor and subjected to continuous bulk polymerization at a reaction temperature of 120 ° C. Then, 0.2 parts by mass of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid as an antioxidant was added, and then the solvent and the unreacted monomer were removed to remove the copolymer. b4 was recovered.

(Manufacturing Example 12)
Under a nitrogen gas atmosphere, 78.2 parts by mass of styrene, 6.8 parts by mass of methacrylic acid, 15 parts by mass of ethylbenzene, and 1,1-bis (t-butylperoxy) cyclohexane (trade name Perhexa C manufactured by Nichiyu Co., Ltd.) ) 0.02 parts by mass was mixed to prepare a raw material composition liquid, charged in a reactor, and continuous bulk polymerization was performed at a reaction temperature of 120 ° C. Then, 0.2 parts by mass of 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid as an antioxidant was added, and then the solvent and the unreacted monomer were removed to remove the copolymer. b5 was recovered.

PSJ polystyrene 685 manufactured by PS Japan Corporation was used as the styrene homopolymer resin (GPPS) used in the comparative example. The styrene homopolymer resin (GPPS) is a styrene homopolymer containing no (meth) acrylic acid (alkyl ester) monomer, and is referred to as polymer c in the present specification.

Table 2 shows various properties of the block copolymers b1 to b5 and the copolymer c obtained in each of Production Examples 8 to 12.

The structures of the copolymers b1 to b5 and the polymer c (hereinafter, also referred to as “(co) polymer b or c”) shown in Table 2 were measured according to the following methods.

<Contents of vinyl aromatic monomer (styrene) of (co) polymer b or c>
The content of the vinyl aromatic monomer unit of the (co) polymer b or c was measured by a UV meter (ultraviolet absorptiometer). Specifically, about 30 mg (accurately weighed to 0.1 mg unit) of the (co) polymer b or c is dissolved in 100 mL of chloroform, the polymer solution is filled in a quartz cell, and the mixture is set in an analyzer. The ultraviolet wavelength of 260 to 290 nm was scanned, and the value of the obtained absorption peak height was determined by the calibration curve method. When the vinyl aromatic monomer is styrene, the peak wavelength appears at 269.2 nm.

<(Meth) acrylic acid (alkyl ester) content of (co) polymer b or c>
The (meth) acrylic acid (alkyl ester) content of the (co) polymer b or c was calculated by subtracting from 100% by mass based on the mass% of the vinyl aromatic monomer unit obtained above.

<(Co) Peak molecular weight of polymer b or c, weight average molecular weight Mw, number average molecular weight Mn, and molecular weight distribution Mw / Mn>
The peak molecular weight, weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the (co) polymer b or c are determined by a gel permeation chromatography (GPC) apparatus as follows. It was measured under the measurement conditions.

(Measurement condition)
GPC device: HLC-8220 manufactured by Tosoh Corporation
Column: Two SuperMultipore HZ-M manufactured by Tosoh Co., Ltd. are connected in series. Column temperature: 40 ° C.
Liquid delivery volume: 0.2 mL / min Detector: Refractometer (RI)

Tetrahydrofuran was used as a solvent, and 10 mL of tetrahydrofuran was added to 50 mg of the polymer for which the molecular weight was measured, and the mixture was completely dissolved and filtered to remove insoluble matters to obtain a sample for GPC measurement.

The specific measurement method is described below. First, a calibration curve was prepared using 9 standard polystyrene samples having different molecular weights and known molecular weights. The weight average molecular weight (Mw) of the lowest molecular weight standard polystyrene was 1090000, and the lowest molecular weight was 1050. Subsequently, the measurement sample was prepared in the above manner using the (co) polymer b or c for measuring the molecular weight.

After confirming that the temperature inside the tank containing the column became constant, a solution sample was injected and measurement was started. After the measurement was completed, the obtained molecular weight distribution curve was statistically processed, and the peak molecular weight, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated. The molecular weight distribution (Mw / Mn) was defined as a value obtained by dividing the obtained weight average molecular weight (Mw) by the number average molecular weight (Mn). The peak molecular weight was determined from the above molecular weight distribution curve.

<VICAT softening temperature of (co) polymer b or c>
Measurements were performed at a heating rate of 50 K / min and a load of 50 N in accordance with the standard ISO306.

<Melt flow rate of (co) polymer b or c>
Measurements were performed at a temperature of 200 ° C. and a load of 5 kgf in accordance with the standard ISO1133.

[Sheet molding of resin composition]
Extrusion molding of a small lab sheet was carried out using the resin compositions of the respective Examples and Comparative Examples described later. Sheet molding is performed using a sheet extruder FS40-36V + TS400 (single shaft screw, with dalmage kneading, screw diameter 40 mm, L / D = 36, T-die width 400 mm, mirror surface roll) manufactured by Ikekai Co., Ltd., and a cylinder temperature of 210 ° C. By adjusting the screw rotation speed and the roll take-up speed at a roll temperature of 70 ° C., single-layer sheets having a thickness of 0.25 mm and 0.60 mm were produced, respectively. Both ends were trimmed by about 30 mm to obtain an original sheet having a width of 220 mm.

<Internal haze value>
The resin sheet obtained above was cut out, placed in an optical quartz cell filled with liquid paraffin, and measured using a haze meter HZ-1 manufactured by Suga Test Instruments. (Unit:%) However, if the haze value exceeds 40%, accurate measurement is not possible as described in ISO14782, so the result of the example is described as "more than 40% (opaque)". did.

<Fold resistance>
The resin sheet obtained above was cut out to prepare a test piece. A BE-201 type (spring type) manufactured by Tester Sangyo was used as a MIT folding resistance tester, and the sample broke at a spring load of 9.8 N, 175 cycles / minute, and a bending angle of 135 ° at room temperature of 23 ° C. The number of times of bending was measured. One round trip was counted as one bending. In addition, the counter attached to the MIT folding resistance tester counts as one time when the sample is in a straight state when the bent part passes underneath, so the first time is practically 0.5 times. However, this was counted as one folding resistance. When performing the MIT folding resistance test, it was visually confirmed in advance that there were no defects in the sheet sample (such as lumps and gels, or burrs on the cut-out end face) at the bent portion of the test piece. If there is a defect, it may break at a value far lower than the actual strength of the sheet. The number of samples is 10, the highest and lowest 2 points are excluded from the data, and the arithmetic mean value of the number of bendings until the remaining 8 points are broken is evaluated as the folding resistance of the sheet based on the following evaluation criteria. did.

Average result of folding resistance by MIT folding resistance tester ◎ +: 2000 times or more ◎: 1000 times or more and less than 2000 times 〇: 500 times or more and less than 1000 times △: 100 times or more and less than 500 times ×: 100 times or less

When cutting out the tanzaku of the test piece from the styrene resin sheet, the one cut out in the longitudinal direction of the tanzaku along the extrusion flow direction was defined as MD, and the one cut out in the direction perpendicular to the extrusion flow direction as the longitudinal direction of the strip was defined as TD. It should be noted that the actual electronic component packaging material such as carrier tape has practically suitable folding resistance in the MD direction. When the number of folding times is 100 or more in either the MD direction or the TD direction, it can be said that the rigidity is sufficient.

<VICAT softening temperature>
The resin sheets obtained above were cut out, the sheet pieces were stacked and heated by a hot press molding machine, and then cooled to prepare strip-shaped test pieces having a width of 10 mm, a thickness of 4 mm, and a length of 50 mm. Using the test piece, the VICAT softening temperature defined by ISO306 was measured at a load of 10 N and a heating rate of 50 ° C./min.

[Examples 1 to 3, Reference Examples 4 to 6, Examples 7 to 14, Reference Examples 15 to 16, Examples 17 to 25, Comparative Examples 1 to 13, Reference Examples 1 to 3]
Using the block copolymer a and the copolymer b produced as described above, dry blending of the pellets with each other at a predetermined blending ratio is performed, and T is performed according to the blending ratios shown in Tables 3 and 4 below. Die extrusion sheet molding was performed to prepare two types of sheets having different thicknesses of 0.25 mm and 0.60 mm. The above-mentioned various characteristics were evaluated using the obtained styrene resin sheet. Further, as a reference example, a milky white translucent sheet (thickness 0.60 mm and 0.25 mm) which has been widely used conventionally and is composed of a composition of a block copolymer and general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS). A similar test was also performed on a PET-G sheet (thickness 0.45 mm) used for various purposes as a transparent sheet. The compounding composition and evaluation results are shown in Tables 3 and 4 below.

From Examples 1 to 3, Examples 7 to 14, and Examples 17 to 25, it is clear that the styrene-based resin sheet of the present invention has excellent transparency. Further, in particular, the conventional milky white composition sheets shown in Reference Examples 1 and 2 have been known to have a large dependence on the folding resistance of the sheet thickness, and are thin sheets of 0.3 mm or less. However, even if a good folding resistance is exhibited, there is a problem that the folding resistance is extremely lowered when a thick sheet of 0.6 mm is used. However, it was found that the styrene-based resin sheet of the present invention has relatively little thickness dependence of the folding resistance, and exhibits good folding resistance even as a thick sheet. Furthermore, it was found that the PET-G sheet shown in Reference Example 3 had a low folding resistance and was significantly inferior to the styrene-based resin sheet of the present invention.
Further, the styrene-based resin sheet of the present invention has appropriate rigidity and heat-resistant deformability, and can be suitably used as a packaging material for electronic parts such as carrier tape.

[Example 26]
Using the block copolymer a2 and the copolymer b2, a three-layer sheet having a front and back layer thickness of 0.03 mm, an intermediate layer thickness of 0.19 mm, and an overall thickness of 0.25 mm was produced. All three-layer sheets had the same composition, and only new materials were used for the front and back layers, and 70% by mass of the new materials and 30% by mass of the trimmed edges were mixed in the intermediate layer. Sheet molding is performed using a three-layer film forming machine manufactured by Plastic Engineering Laboratory Co., Ltd. (each with a single-screw screw and a madock, screw diameter 32 mm, L / D = 28, T-die width 400 mm, mirror surface roll), and a cylinder temperature of 210. A three-layer sheet was produced by adjusting the screw rotation speed and the roll take-up speed at ° C. and a roll temperature of 70 ° C. The compounding composition and evaluation results are shown in Table 5 below.

[Examples 27 and 28]
Using the 0.25 mm-thick styrene resin sheets obtained in Examples 22 and 26, the carrier tape was heated at 110 ° C. and press-molded to form a carrier tape having a pocket portion capable of accommodating electronic components (Example). 28 and Example 29). The obtained carrier tape has transparency, appropriate rigidity, and heat resistance, does not break easily even when bent intentionally, and has excellent folding resistance, and can be suitably put into practical use. rice field.

The resin sheet of the present invention has industrial applicability, especially as a packaging material for electronic parts.

Claims (6)

A resin sheet containing a block copolymer composition containing a block copolymer a and a copolymer b.
The block copolymer a is a block including a polymer block mainly composed of at least one vinyl aromatic hydrocarbon monomer unit and a polymer block mainly composed of at least one conjugated diene monomer unit. It is a polymer,
The mass ratio of the vinyl aromatic hydrocarbon monomer unit in the block copolymer a to the conjugated diene monomer unit is the former / the latter = 65/35 to 80/20 .
In the molecular weight distribution curve measured by the gel permeation chromatography measurement method, at least one peak molecular weight derived from the block copolymer a is present within the range of the molecular weight of 30,000 or more and 300,000 or less, and the block copolymer is present. The number average molecular weight (Mn) of the polymer block S composed of the vinyl aromatic hydrocarbon monomer unit in a is 10,000 or more and 60,000 or less, and the molecular weight distribution (Mw / Mn) of the polymer block S is determined. 1.5 or more and 4.0 or less,
The copolymer b is a random copolymer of a vinyl aromatic hydrocarbon monomer unit and a (meth) acrylic acid and / or a (meth) acrylic acid alkyl ester monomer unit.
The mass ratio of the vinyl aromatic hydrocarbon monomer unit in the copolymer b to the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit is the former / the latter = 50. It is / 50 to 90/10,
A resin sheet having an internal haze value of 4.0% or less measured in accordance with ISO 14782. The resin sheet according to claim 1, wherein the folding resistance measured in accordance with JIS P 8115 is 500 times or more in both the MD direction and the TD direction. The resin sheet according to claim 1 or 2, wherein the block copolymer a has at least two polymer blocks mainly composed of vinyl aromatic hydrocarbon monomer units. The resin sheet according to any one of claims 1 to 3 , wherein the internal haze value measured in accordance with ISO 14782 is 2.0% or less. Any one of claims 1 to 4 , wherein the (meth) acrylic acid and / or the (meth) acrylic acid alkyl ester monomer unit, which is the constituent unit of the copolymer b, is a methyl methacrylate monomer unit. The resin sheet described in the section. A packaging material for electronic parts, which is a molded body of the resin sheet according to any one of claims 1 to 5 .