JP2002121236A - Storage case for recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage case for a recording medium excellent in impact strength and transparency aiming at preventing damage or the like occurred when the recording medium is transported, stored and handled, safelyprotecting information in an upgraded recording medium and besides improving design by inserting a printed matter. SOLUTION: This storage case for the recording medium comprises a resin composition containing as a main component a rubber-modified thermoplastic resin obtained by using a rubber-like polymer having a strong affinity to a mixture of an aromatic vinyl compound with an alkyl (meth)acrylate and a specific structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium storage case containing an improved aromatic vinyl copolymer resin as an essential component and having excellent impact resistance and excellent transparency. . More specifically, an aromatic vinyl- (meth) acrylic acid alkyl ester-based copolymer consisting of an aromatic vinyl-based structural unit having a specific ratio and one or more alkyl (meth) acrylate-based structural units is used as a continuous phase. A recording composed of a resin composition containing, as an essential component, a rubber-modified aromatic vinyl copolymer resin having excellent transparency, impact strength, etc., containing rubber-like polymer dispersed particles having a glass transition point as a dispersed phase. It relates to a medium storage case.

[0002]

2. Description of the Related Art A recording medium storage case includes, for example, a pair of covers (cases) provided on both sides of a resin base (tray) so as to be openable and closable. In some cases, recording media such as CDs (compact discs) and DVDs (digital video discs) are detachably stored. As a representative material, in order to express high designability,
In many cases, printed matter is inserted into the case, and it is required to have excellent transparency. Also, the case is required to have excellent rigidity / dimensional stability, and polystyrene resin (GPPS) is used as a material satisfying these requirements. ) Is used. Recently, CD-ROM, CD-R, CD-RW and DV
With the advent of D, recorded information has been increasing in density and capacity, and the storage case itself has been required to have high strength in order to protect the information. However, GPPS has a low impact strength, and there is a concern that the product value may be reduced due to breakage of the case during transportation and storage, and that the recording medium itself may be adversely affected.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent breakage or the like during transport, storage and handling of a recording medium, to safely protect information on an advanced recording medium, and to enhance the design by inserting a printed material. Accordingly, the present invention provides a recording medium container excellent in impact strength and excellent in transparency. Therefore, as an attempt to obtain a recording medium storage case having excellent impact strength and transparency, a rubber-modified thermoplastic resin obtained by polymerizing a mixed solution composed of styrene, alkyl (meth) acrylate and a butadiene rubber-based polymer was used. Has been developed as a recording medium storage case. For example, Japanese Patent Application Laid-Open No. 10-17061 discloses a rubber-modified polymer obtained by graft-polymerizing a styrene-based monomer and a (meth) acrylic acid ester onto a rubbery polymer, and a resin component containing a polyorganosiloxane. A recording medium storage case as a component is described. However, the impact strength and transparency of the recording medium storage case containing such a rubber-modified thermoplastic resin as one component are still insufficient, and have not yet sufficiently satisfied such market requirements.

[0004]

In view of the above situation, the present inventors have made intensive studies to solve the above-mentioned problems. As a result, in obtaining a rubber-reinforced transparent resin, an aromatic vinyl compound and a ) A styrene-butadiene block copolymer structure having a specific structure, which is particularly suitable for graft copolymerization with a mixture of acrylic acid alkyl ester compounds and has a strong affinity for the mixture, has been found. Then, a rubber-modified thermoplastic resin obtained by graft-polymerizing a styrene-based monomer and a (meth) acrylate using the styrene-butadiene block copolymer having this specific structure as a rubber-like polymer is used. The present inventors have found that a recording medium storage case excellent in impact strength and transparency can be obtained, and have completed the present invention. That is, the present invention relates to a rubber-modified aromatic vinyl copolymer resin containing a rubbery polymer as dispersed particles in a continuous matrix resin, wherein (1) the continuous matrix has a refractive index substantially equivalent to that of the rubbery polymer. Wherein a mixed solution of 20 to 80% by weight of an aromatic vinyl compound having at least one structural unit and 20 to 80% by weight of an alkyl (meth) acrylate compound having at least one structural unit is copolymerized. (2) the content of the rubbery polymer is 3 to 20% by weight based on the rubber-modified aromatic vinyl copolymer resin, and (3) the average particle diameter of the rubbery polymer dispersed particles is 0.3. ２．１2.1 μm,
(4) And the glass transition point of the dispersed particles is -75 to -3.
The present invention relates to a recording medium storage case comprising a resin composition containing a rubber-modified aromatic vinyl copolymer resin in a temperature range of 0 ° C. as an essential component.

Hereinafter, the present invention will be described in detail. The rubber-modified aromatic vinyl copolymer resin constituting the present invention, in the presence of a rubbery polymer, an aromatic vinyl compound and (meth)
Alkyl acrylate compound is copolymerized, or aromatic vinyl compound obtained by copolymerizing aromatic vinyl compound and (meth) acrylic acid alkyl ester compound and, if necessary, one or more compounds which can be copolymerized with them. It was obtained as a system copolymer. Here, as the aromatic vinyl compound, for example, in addition to styrene, α-alkyl-substituted styrene such as α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-
Nuclear alkyl-substituted styrenes such as methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p
Styrene compounds conventionally known for rubber-modified styrene resins, such as halogenated styrenes such as bromostyrene, 2-methyl-1,4-chlorostyrene, and 2,4-dibromostyrene, and vinylnaphthalene. One or a mixture of two or more of the above is used, and a typical one is styrene alone or a part of which is replaced with the above-mentioned aromatic vinyl compound other than styrene.

The alkyl (meth) acrylate compounds include methyl methacrylate, ethyl methacrylate, butyl methacrylate, methoxyethyl acrylate,
Lauryl methacrylate, tridecyl methacrylate, palmitin methacrylate, pentadecyl methacrylate, stearyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, lauryl acrylate, tridecyl acrylate, palmitin acrylate, pentadecyl acrylate, acrylic acid Stearyl and the like.

The compound which can be copolymerized with the aromatic vinyl compound and the alkyl (meth) acrylate compound constituting the aromatic vinyl copolymer resin of the present invention includes, for example, acrylonitrile, methacrylonitrile, fumaronitrile, Vinyl cyanide such as maleonitrile and α-chloroacrylonitrile; maleimide such as methacrylic acid, acrylic acid, maleic anhydride and phenylmaleimide; vinyl acetate and divinylbenzene; and aromatic vinyl compounds and alkyl (meth) acrylates. Used as a mixture with an ester compound. The rubbery polymer used in the rubber-modified aromatic vinyl copolymer resin of the present invention needs to have a glass transition point of the particles dispersed in the matrix in the range of -75 to -30 ° C. And the rubbery polymer is preferably a block part (A) composed of a random or tapered copolymer of styrene and butadiene and a styrene butadiene copolymer block part composed of styrene homopolymer or mostly styrene ( And B) a block copolymer.
In this block copolymer, a block portion (A) composed of a random or tapered copolymer of styrene and butadiene is used to obtain a rubber-reinforced transparent resin.
It has a molecular structure that has a strong affinity for a mixture of an aromatic vinyl compound and an alkyl (meth) acrylate compound. A rubber-modified thermoplastic resin obtained by graft-polymerizing an aromatic vinyl compound and an alkyl (meth) acrylate compound using a styrene-butadiene block copolymer having this structure as a rubber-like polymer is used. Thereby, a recording medium storage case excellent in impact strength and transparency can be obtained.

A block copolymer (A) composed of a random or tapered copolymer of styrene and butadiene and a block copolymer (B) composed of a styrene homopolymer or a styrene butadiene copolymer composed mostly of styrene Among the unions, (a) 5% to 35% by weight of styrene and 65% to 9% by weight of butadiene are preferred.
5% by weight butadiene / styrene random or tapered copolymer block (A) and styrene 9
A styrene homopolymer or a butadiene / styrene copolymer block portion (B) comprising 0% to 100% by weight and 0% to 10% by weight of butadiene;
(B) The glass transition point of the random or tapered copolymer block portion (A) of butadiene and styrene is -80.
To -35 ° C, and (c) the ratio of 1,2-vinyl bonds among the unsaturated bonds based on butadiene is 8.0 to 20.
0% by weight, and (d) a styrene-butadiene-based block copolymer in which the viscosity of a 5% by weight styrene solution at 25 ° C. is in the range of 20 to 50 centipoise. Still more preferably, (a) styrene 10% by weight to 2%
A random or tapered copolymer block part (A) of butadiene and styrene comprising 5% by weight and 75% to 90% by weight of butadiene, and 95% by weight to 100% of styrene.
(B) a random or tapered copolymer block of butadiene and styrene (B) consisting of a styrene homopolymer or a butadiene and styrene copolymer block (B) comprising 0% to 5% by weight of butadiene and 0% to 5% by weight of butadiene. ) Is in the range of −80 to −40 ° C., and (c) 1,2 of butadiene-based unsaturated bonds.
The ratio of vinyl bonds is 10.0 to 17.0% by weight,
(D) The viscosity of a 5% by weight styrene solution at 25 ° C. is 20
It is desirable that the styrene-butadiene block copolymer be in the range of -40 to 40 centipoise.

A block copolymer (A) composed of a random or tapered copolymer of styrene and butadiene and a block copolymer (B) composed of a styrene homopolymer or a styrene butadiene copolymer composed mostly of styrene When the composition of the butadiene unit and the styrene unit constituting the block portion (A) is out of the range of 65% to 95% by weight of butadiene and 5% to 35% by weight of styrene, respectively, Impact resistance and transparency are reduced. Also, when the composition of the styrene unit and the butadiene unit constituting the block portion (B) is out of the range of 90% by weight to 100% by weight of styrene and 0% by weight to 10% by weight of butadiene, respectively, the resistance of the recording medium storage case is improved. Impact and transparency are reduced. Further, the glass transition point of the block portion (A) is -80 to -3.
If the temperature is out of the range of 5 ° C., the impact resistance and the transparency of the recording medium storage case decrease. If the binding ratio of 1,2 vinyl exceeds 20% by weight, the morphology and particle size of the rubber particles become irregular, while if it is less than 8% by weight, the graft ratio decreases and the rubber morphology also becomes irregular. The medium storage case has poor impact resistance. And 5% by weight at 25 ° C
The viscosity of the styrene solution is less than 20 centipoise, or 5
If it exceeds 0 centipoise, the particle size of the dispersed rubber particles becomes irregular, resulting in poor transparency and reduced impact resistance of the resulting recording medium storage case.

[0010] In addition, as long as the effects of the present invention are not impaired,
Boundary part (A) of block part (A) composed of random or tapered copolymer of styrene and butadiene and styrene butadiene copolymer block part (B) composed of styrene homopolymer or most of styrene
And / or (B) may have a butadiene block at a part of both terminals, and a common styrene-butadiene-based block copolymer may be used in the same manner. Here, the styrene / butadiene random copolymer block portion (A) refers to a copolymer block portion having a structure in which the bonding mode of styrene and butadiene is randomly and uniformly distributed along the polymer chain. The butadiene tapered copolymer block portion (A) refers to a copolymer block portion in which the bonding mode of styrene and butadiene has a gradient structure of styrene and butadiene composition along the polymer chain or a structure corresponding thereto.

The rubbery polymer used in the rubber-modified aromatic vinyl copolymer resin of the present invention is produced by a usual living anion polymerization method using an organolithium catalyst in a hydrocarbon solvent. It is not limited to this method. When the rubbery polymer is produced in a hydrocarbon solvent using an organolithium catalyst, examples of the organolithium catalyst include n-propyllithium, isopropylpropyllithium, n-butyllithium, and the like.
sec-butyllithium, tert-butyllithium,
Methyllithium, ethyllithium, n-hexyllithium, cyclohexyllithium, benzyllithium, lithium naphthalene and the like are used, and preferably, n-butyllithium and sec-butyllithium are used. As the hydrocarbon solvent, pentane, n-hexane, n-heptane, isooctane, aliphatic hydrocarbons such as n-decane,
Alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane, and aromatic hydrocarbons such as benzene, xylene, and toluene are used. Further, a polar substance may be produced in the presence of a polymerization system. Polar substances include triethylamine, tri-n-butylamine, pyridine, N,
N, N ', N'-tetramethylethylenediamine, hexamethylphosphoramide, triphenylphosphine, diethyl ether, tetrahydrofuran, dioxane, ethylene glycol methyl ether, diethylene glycol dimethyl ether, potassium butoxide, sodium butoxide and the like are preferable. , N, N ',
N'-tetramethylethylenediamine, tetrahydrofuran and the like are used.

The rubbery polymer used in the present invention is a random or tapered copolymer block portion (A) of butadiene and styrene and a styrene homopolymer or a styrene butadiene copolymer block mainly composed of styrene. A styrene-butadiene-based block copolymer composed of Part (B) is used. As a method for producing such a styrene-butadiene-based block copolymer by an ordinary living anion polymerization method, for example, an organic lithium-based catalyst is used. A mixture of butadiene and styrene is supplied at a polymerization rate lower than the polymerization rate of the monomer at a set polymerization temperature in a hydrocarbon solvent in which is present (e.g., JP-B-38-2394). Described method). That is, polymerization is performed while supplying a monomer mixture having a desired ratio of butadiene and styrene at a rate lower than the polymerization rate, and if necessary, then supplying a monomer mixture having a different composition ratio of butadiene and styrene at a rate lower than the polymerization rate. If necessary, this operation is repeated one or more times to obtain the block copolymer of the present invention. In addition, application of a method of adding a polar substance to a polymerization system containing an organolithium catalyst (for example, a method described in JP-B-36-15386) can also be mentioned as a production method by a living anion polymerization method. . That is, in a polymerization system containing an organolithium catalyst and a polar substance, a monomer mixture having a desired butadiene / styrene composition ratio is polymerized, and if necessary, a monomer mixture having a different butadiene / styrene composition ratio is added. The block copolymer of the present invention can also be obtained by repeating this operation once or more if necessary. A method based on a combination of these methods is also possible.

In the production of the rubber-modified aromatic vinyl copolymer resin of the present invention, an organic solvent can be used if necessary. Examples of the organic solvent include benzene, toluene, xylene, ethylbenzene, acetone, isopropylbenzene, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, and the like. Particularly, aromatic hydrocarbons such as toluene and ethylbenzene alone or a mixture of two or more thereof are used. It is preferable that other solvents such as aliphatic hydrocarbons and dialkyl ketones be used in combination with aromatic hydrocarbons as long as the dissolution of the rubbery polymer is not impaired. The rubbery polymer is composed of an aromatic vinyl compound and an alkyl (meth) acrylate compound or an aromatic vinyl compound and an alkyl (meth) acrylate compound and a monomer copolymerizable therewith, or a solvent. Dissolved in the mixture. When an organic solvent is used, the concentration of the monomer in the polymerization solution and the concentration of the produced copolymer are reduced, so that the polymerization rate is reduced to an easily controllable level, thereby preventing runaway of the polymerization reaction. In addition, the viscosity of the polymerization liquid decreases, and the uniform mixing of the polymerization liquid and the movement of the polymerization liquid are facilitated, so that the operability as a production process is improved.

However, if the concentration of the organic solvent in the polymerization solution is too high, the polymerization rate is too low, and the productivity is reduced. It is not preferable because the polymer particles easily aggregate and the transparency of the resin decreases. In addition, the recovery energy of the solvent becomes large and the economic efficiency becomes poor. Therefore, the concentration of the organic solvent in the reaction vessel is usually in the range of 5 to 50 parts by weight based on 100 parts by weight of the total amount of the polymerization solution. The solvent may be added after the polymerization conversion rate at which the viscosity becomes relatively high, or may be added before the polymerization. It is preferable to add them before polymerization in view of uniformity of quality and control of polymerization temperature. When polymerizing a monomer, it may be polymerized in the temperature range of 110 to 190 ° C. in the absence of a polymerization initiator, or 50 to 180 ° C. using an organic peroxide that generates a radical as a polymerization initiator. The polymerization can be carried out in a temperature range of preferably 90 to 150 ° C, but it is preferable to carry out the polymerization in the presence of a peroxide.

In the present invention, a polymerization initiator can be used. The organic peroxide used is 2,2-bis (t-butylperoxy) butane, 2,2-bis (t-
Peroxyketals such as butylperoxy) octane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate; -Butyl peroxide, t-butylcumyl peroxide, sicumyl peroxide, α, α'-bis (t-
Dialkyl peroxides such as butyl peroxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5 di (t-butylperoxy) hexyne-3,
Acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4 dichlorobenzoyl peroxide, m- Diacyl peroxides such as toluoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n-propylperoxydicarbonate, di-3-methoxybutylperoxydicarbonate, di2
Peroxycarbonates such as ethoxyethyl peroxydicarbonate, dimethoxyisopropyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t- Butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypiparate, t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexano Ethate, t-butyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxy laurate, t-butyl peroxybenzoate, di-t-butyl diperoxy isophthalate, 2,5-dimethyl-2,5 (Benzoi) Peroxy esters such as peroxy) hexane and t-butylperoxyisopropyl carbonate; ketone peroxides such as acetylacetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide , T-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,5-dimethylhexane 2,5 dihydroperoxide, 1,1,3,3
-Hydroperoxides such as tetramethylbutyl hydroperoxide, polyacyl peroxides of dibasic acid, polyperoxyesters of dibasic acid and polyol, and one or more initiators are used. it can. The use of an organic peroxide is preferred because high grafting efficiency can be easily obtained. The amount of use is not particularly limited, but is preferably 0.001 to 5.0 parts by weight based on 100 parts by weight of the monomer mixture.

In the polymerization, a chain transfer agent such as mercaptans, α-methylstyrene linear dimer,
Monoterpenoid-based molecular weight regulator (turbinolene),
Examples of antioxidants include hindered phenols, hindered bisphenols, hindered trisphenols, and the like, for example, 2,6-di-tert-butyl-4-methylphenol, stearyl-β- (3,5-di-tert-butyl-4-hydroxy). (Phenyl) propionate may be used.

The resins obtained by the above polymerization methods include:
Commonly known additives, i.e. known antioxidants, for example 2,6-di-tert-butyl-4-methylphenol, 2- (1-methylcyclohexyl) 4,6
-Dimethylphenol, 2,2'-methylene-bis (4
-Ethyl-6-tert-butylphenol), 4,
Inorganic stabilizers such as 4'-thiobis- (6-tert-butyl-3-methylphenol), dilaurylthiodipropionate, tris (dinonylphenyl) phosphite, calcium and tin; known ultraviolet absorbers such as pt
tert-butylphenyl salicylate, 2,2'-dihydroxy-4-methoxybenzophenohen, 2- (2 '
-Hydroxy-4'-n-octoxyphenyl) benzothiazole; known flame retardants such as antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, chlorinated paraffin, tetrabromobutane, hexabromobutane, tetrabromobisphenol A Known antistatic agents, for example stearoamidopropyldimethyl-β
-Hydroxyethylammonium nitrate; known colorants, such as titanium oxide, carbon black, other inorganic or organic pigments; known fillers, such as calcium carbonate, clay, silica, glass fiber, glass spheres, carbon fiber, reinforcing MBS, SBR,
SBS, SIS, or a hydrogenated product thereof can be added as needed, but is not limited thereto. Further, when these additives are blended with the resin, the additives may be blended alone or a plurality of kinds of additives may be blended. Furthermore, it can be blended with another resin and provided for molding. Further, these additives may be added at an intermediate stage of the polymerization process.

In the present invention, the molecular weight of the matrix resin can be controlled by changing the type, amount and timing of addition of the chain transfer agent. Also,
The particle size of the rubber-dispersed particles can be controlled by changing the stirring conditions as well as the type, amount and timing of addition of the chain transfer agent. In order to maintain transparency, a method is used that does not change the composition of the polymer formed during the polymerization process. For example, a method of adding a monomer as needed during the polymerization or a method of continuously adding the monomer after the addition is used.

In the rubber-modified aromatic vinyl copolymer resin containing the rubbery polymer as dispersed particles in the continuous matrix resin according to the present invention, the continuous matrix has a refractive index substantially equal to that of the rubbery polymer. And a mixed solution of 20 to 80% by weight of an aromatic vinyl compound having at least one structural unit and 20 to 80% by weight of an alkyl (meth) acrylate compound having at least one structural unit. Preferably, the continuous matrix has a refractive index substantially equivalent to that of the rubber-like polymer, and has a structural unit of 40 to 65% by weight of an aromatic vinyl compound having at least one kind of (meth) acrylic acid. It is desirable that a mixed solution comprising 35 to 60% by weight of the alkyl ester compound is copolymerized. When the mixed solution comprising one or more aromatic vinyl compounds and one or more alkyl (meth) acrylate compounds has a composition outside the above range, the transparency of the obtained recording medium storage case decreases, Not preferred.

In the rubber-modified aromatic vinyl copolymer resin of the present invention, the content of the rubbery polymer is 3 to 20% by weight based on the rubber-modified aromatic vinyl copolymer resin. Preferably, the content of the rubbery polymer is 5 to 20% by weight based on the rubber-modified aromatic vinyl copolymer resin. If the content of the rubber-like polymer is less than 3% by weight based on the rubber-modified aromatic vinyl copolymer resin, the impact strength of the obtained recording medium storage case decreases, which is not preferable. On the other hand, if the content of the rubbery polymer exceeds 20% by weight based on the rubber-modified aromatic vinyl copolymer resin, the transparency of the recording medium storage case obtained is undesirably reduced. Further, the average diameter of the dispersed particles of the rubber-like polymer derived from the rubber-modified aromatic vinyl copolymer resin is in the range of 0.3 to 2.1 μm, and the glass transition point of the dispersed particles is −75 to −−.
It must be in the range of 30 ° C. More preferably, the average particle size of the dispersed particles of the rubbery polymer derived from the rubber-modified aromatic vinyl copolymer resin is in the range of 0.5 to 1.0 μm, and the glass transition point of the dispersed particles is − 75-
It is desirable to be in the range of -40 ° C. If the average particle size exceeds 2.1 μm, the transparency of the obtained recording medium storage case becomes poor, and if it is less than 0.3 μm, the impact strength of the recording medium storage case decreases, which is not preferable. As used herein, the average particle size is determined by measuring dimethylformamide as a dispersant with LS-230 (trademark of a particle size analyzer manufactured by Coulter, USA) to obtain a volume average value. The particle size distribution state is not particularly limited, and may be a single peak distribution state or a double mountain distribution state. Further, the glass transition point of the dispersed particles of the rubbery polymer derived from the rubber-modified aromatic vinyl copolymer resin is -75 to -30.
When the temperature is out of the range, the transparency and impact strength of the recording medium storage case decrease, and the balance of physical properties becomes insufficient.

Further, various plasticizers and lubricants can be added to the rubber-modified aromatic vinyl copolymer resin of the present invention according to the purpose. Any known plasticizer can be used. For example, phthalic acid such as dibutyl phthalate, dioctyl phthalate, diheptyl phthalate, butyl benzyl phthalate, butyl phthalyl butyl glycolate, and di-n-butyl adipate;
Adipic acid such as di- (2-ethylhexyl adipate), citric acid such as acetyl tri-n-butyl citrate, sebacic acid such as di-n-butyl sebacate, di- (2-ethylhexyl) sebacate, epoxidation Epoxy such as soybean oil, epoxidized linseed oil, epoxidized fatty acid ester, and dibasic acids such as succinic acid, glutaric acid, adipic acid, and ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,
Examples thereof include polyesters comprising a dihydric alcohol having a molecular weight of 200 or less, such as 2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol. Any known lubricant can be used. For example, metal soaps, hydrocarbon liquid paraffin, polyethylene wax, etc., fatty acid-based higher fatty acids, oxy fatty acids, etc., ester glycerides, ester waxes, etc., fatty acid amide-based fatty acid amides, bis fatty acid amides, etc. And fatty acid ketones, composite lubricants and the like. Specific examples include paraffin wax, stearic acid, hardened oil, stearamide, ethylenebisstearylamide, n-butyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride, polysiloxane,
And alkyl phosphates. The method for adding the plasticizer and the lubricant is not particularly limited.

A method for producing a recording medium storage case from the obtained rubber-modified aromatic vinyl copolymer resin can be obtained by injection molding which is generally used.

Embodiments of the present invention will be described below. First, the rubber-modified aromatic vinyl copolymer resin containing a rubbery polymer as dispersed particles of the present invention can be produced by a conventionally known method. That is, the rubbery polymer is dissolved in a raw material solution composed of an aromatic vinyl compound and an alkyl (meth) acrylate compound, a polymerization solvent as needed, and a polymerization initiator, and is dissolved in the presence of a generally used radical catalyst. In the presence, the raw material is fed to a reactor equipped with a stirrer to carry out polymerization. The polymerization temperature can be determined in consideration of the fluidity and productivity of the rubber-modified aromatic vinyl copolymer resin, the heat removal capability of the reactor, and the like. After completion of the polymerization, a treatment is performed under vacuum to remove unreacted monomers, polymerization solvent, and the like, to obtain a rubber-modified aromatic vinyl copolymer resin.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The data shown in Examples and Comparative Examples were measured according to the following methods. The molecular weight distribution of the styrene-butadiene-based block copolymer rubber was measured by the GPC method under the following conditions. Solvent (mobile phase): THF, deaerator: ER manufactured by ERMA
C-3310, pump: JASCO PU-980, flow rate 1.0 ml / min, autosampler: Tosoh AS-8
020, column oven: L-5030 manufactured by Hitachi, Ltd.
Set temperature 40 ° C, Column composition: Tosoh TSKgurdco
One lumn MP (× L) 6.0mmID × 4.0cm and TSK-GEL MULTIPORE HXL-M manufactured by Tosoh Corporation
7.8 mm ID × 30.0 cm 2 lines, 3 lines in total, detector: RI Hitachi, Ltd. L-3350, data processing: SIC480 data station.

The glass transition point of the styrene-butadiene-based block copolymer rubber (A) can be determined by
It measured using the SC-200 and SSC-5000 series under the following conditions. The temperature is raised from room temperature to the melting point of polystyrene plus the temperature of alpha, held at that temperature for about 10 minutes, and cooled at a cooling rate of 20 to 25 ° C / min to the glass transition temperature of polybutadiene minus the temperature of alpha (n
= 1), the temperature is raised again to the temperature of the melting point of polystyrene plus alpha, and the temperature is maintained for about 10 minutes,
The polybutadiene was cooled at a cooling rate of ° C./min to the glass transition temperature minus the temperature of alpha (n = 2) and the average of the two measurements was recorded. Rubber modified aromatic vinyl
The glass transition point of the dispersed particles dispersed in the alkyl (meth) acrylate copolymer was determined by measuring the rubber-modified aromatic vinyl copolymer resin sample a (accurately weighing about 1 g) to 4/6 (volume) of acetone / methyl ethyl ketone. Ratio) Dispersed in 30 cc of a mixed solvent, insoluble matter was separated by a centrifugal separation method, and dried to obtain DSC-200, SSC-5 manufactured by Seiko Denshi Kogyo KK
Using the 000 series, the measurement was performed under the following conditions. From room temperature, the temperature is raised to the temperature of the melting point of polystyrene plus the temperature of alpha, held at that temperature for about 10 minutes, and cooled at a cooling rate of 20 to 25 ° C./min to the glass transition temperature of polybutadiene minus the temperature of alpha (n = 1). ), Raise the temperature again to the melting point of polystyrene plus the temperature of alpha, hold at that temperature for about 10 minutes, and cool at a cooling rate of 20-25 ° C / min to the glass transition temperature of polybutadiene minus the temperature of alpha (n = 2) ) The average of the two measurements was recorded.

The microstructure of the styrene-butadiene-based block copolymer rubber, in particular, the vinyl bond content and styrene content of the butadiene portion were determined by infrared spectroscopy.
n, Anal. Chem., 21, 923 (1949)), and the styrene solution viscosity was measured by an Ostwald viscometer. The graft ratio of the rubber-modified aromatic vinyl-based copolymer resin was as follows:
(Accurately weigh 1 g) with acetone / methyl ethyl ketone 4
/ 6 (volume ratio) in a mixed solvent of 30 cc, insoluble matter was separated by centrifugation and dried, and the weight (S2) of the insoluble matter was precisely weighed and determined by the following equation (1). Here, S3 indicates the content of the rubbery polymer in the sample S1. {Formula 1} Graft rate (g) = [(S2 / S1) -S3]
/ S3 × 100 The swelling index was determined by measuring the sample S4 (approximately 1 g)
After stirring for 1 hour to dissolve, the supernatant was removed by centrifugation, the weight of the remaining swollen matter (S5) was precisely weighed, and then the remaining swollen matter was dried by vacuum drying. It is a characteristic value determined by the following formula 2 based on the result of precisely weighing the weight (S6) of the dry solid content to be obtained. {Formula 2} Swelling index = S5 / S6 The amount of the polybutadiene rubber component in the rubber-modified styrene-based copolymer resin was determined by a halogen addition method in which iodine chloride was added to a double bond and measured.

Various characteristics of the recording medium storage case were determined as follows. 1) Storage case haze value: JIS K-6714 (evaluation of the transparency of the flat part of the molded article) 2) Storage case drop test: (As a strength evaluation of the storage medium storage device, a commercially available CD is mounted on the storage container. Damage situation when dropped on concrete floor from height 2m, 10
(Evaluation results in which "0" indicates no crack generation in the test material, "○" indicates 1-3, and "x" indicates four or more)

[0027]

EXAMPLE 1 A styrene-butadiene random copolymer (A) constituting the styrene-butadiene block copolymer rubber was prepared from styrene-butadiene random copolymer rubbers such as US Pat. No. 3,094,512. A method, that is, a production condition that generally satisfies the relationship of polymerization rate> styrene-butadiene mixed monomer supply rate under a certain condition, is generally used. The concrete implementation method is as follows. A stainless steel polymerization tank having an inner volume of 1000 L with a jacket, a coil and a stirrer is washed with cyclohexane dehydrated to a water content of 10 ppm or less, replaced with nitrogen, and then dehydrated to a water content of 10 ppm or less under a nitrogen gas atmosphere. Then, 540 kg of cyclohexane containing 139 ppm of tetrahydrofuran was charged into the polymerization tank, and the internal temperature was raised to 80 ° C.
0.8 kg of a 0 wt% cyclohexane solution was added.
Next, 8.75 kg / h of styrene dehydrated to a water content of 10 ppm or less and 35 kg / h of butadiene dehydrated by passing through a molecular sieve at a constant internal temperature of 80 ° C.
Were simultaneously fed for 4 hours to carry out polymerization. Thereafter, 55 kg of styrene dehydrated to a water content of 10 ppm or less was added at 80 ° C., and polymerized for 10 minutes at a maximum temperature not exceeding 120 ° C. to polymerize all the charged styrene.

Thereafter, the polymerization solution is transferred to the next reaction tank,
After 0.08 parts by weight of water was added to 100 parts by weight of the polymer to terminate the polymerization, carbon dioxide was added and neutralized during the transfer to the next reaction tank. Next, 2,4, -bis
[(Octylthio) methyl] -O-cresol was added at a rate of 0.2% to the polymer, the solvent was removed by steam stripping, dried with a hot roll at 100 ° C, and dried with a styrene-butadiene block copolymer. A united rubber was obtained. 7.9% by weight of the styrene butadiene block copolymer rubber was 46.6% by weight of a styrene monomer, 32.5% by weight of methyl methacrylate, and butyl acrylate.
100 parts by weight of a solution dissolved in 6% by weight and 8.4% by weight of ethylbenzene and 0.01,1,1-bis (tert-butylperoxyl) 3,3,5-trimethylcyclohexane
A solution consisting of 0.05 parts by weight and 0.08 parts by weight of t-dodecyl mercaptan was continuously fed into the first polymerization machine,
After performing a stirring polymerization reaction at a polymerization temperature of 5 ° C. for an average residence time of 3 hours, the whole amount was continuously charged into a plug flow type reactor so that the residence time was 5 hours, and polymerization was performed. In this way, the polymerization was carried out to a polymerization rate of 85%, and the solution was fed to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, cut with a cutter, and pelletized. Resin was obtained. Next, the obtained resin is 142 m in thickness and 1 mm in thickness with an injection molding machine.
A recording medium of mx 124 mm x 10 mm formed a CD storage container. Tables 1 and 2 show various analytical values and the results of evaluation of physical properties of the recording medium storage case.

[0029]

Example 2 The styrene-butadiene random copolymer (A) constituting the styrene-butadiene-based block copolymer rubber was produced from styrene-butadiene-based random copolymer rubbers such as US Pat. No. 3,094,512. A method, that is, a production condition that generally satisfies the relationship of polymerization rate> styrene-butadiene mixed monomer supply rate under a certain condition, is generally used. The concrete implementation method is as follows. A stainless steel polymerization tank having an inner volume of 1000 L with a jacket, a coil and a stirrer is washed with cyclohexane dehydrated to a water content of 10 ppm or less, replaced with nitrogen, and then dehydrated to a water content of 10 ppm or less under a nitrogen gas atmosphere. Then, 540 kg of cyclohexane containing 139 ppm of tetrahydrofuran was charged into the polymerization tank, and the internal temperature was raised to 80 ° C.
0.8 kg of a wt% cyclohexane solution was added. Next, at a constant internal temperature of 80 ° C., 3.89 kg / h of styrene dehydrated to a water content of 10 ppm or less and 35 kg / h of butadiene dehydrated by passing through a molecular sieve were fed and polymerized simultaneously for 4 hours. Then, moisture content 1
75 kg of styrene dehydrated to 0 ppm or less was added at 80 ° C., and polymerized for 10 minutes at a maximum temperature not exceeding 120 ° C. to polymerize all the charged styrene.

Thereafter, the polymerization solution is transferred to the next reaction tank,
After 0.08 parts by weight of water was added to 100 parts by weight of the polymer to terminate the polymerization, carbon dioxide was added and neutralized during the transfer to the next reaction tank. Next, 2,4, -bis
[(Octylthio) methyl] -O-cresol was added at a ratio of 0.2% to the polymer, the solvent was removed by steam stripping, and the mixture was dried with a hot roll at 100 ° C to obtain a styrene-butadiene block. A heavy rubber was obtained. 7.9% by weight of the styrene butadiene block copolymer rubber was 46.6% by weight of a styrene monomer, 32.5% by weight of methyl methacrylate, and butyl acrylate.
100 parts by weight of a solution dissolved in 6% by weight and 8.4% by weight of ethylbenzene and 0.001,1,1-bis (tert-butylperoxyl) 3,3,5-trimethylcyclohexane
A solution consisting of 5 parts by weight and 0.08 parts by weight of t-dodecyl mercaptan was continuously fed into the first polymerization machine, and 125
After carrying out the stirring polymerization reaction at a polymerization temperature of 3 ° C. for an average residence time of 3 hours, the whole amount was continuously charged into a plug flow type reactor so that the residence time was 5 hours, and polymerization was carried out. In this way, the polymerization is carried out to a polymerization rate of 85%, and the solution is supplied to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, and cut with a cutter. Thus, a pellet-shaped resin was obtained. Next, the obtained resin was molded to a thickness of 1 mm and a size of 14 using an injection molding machine.
A recording medium of 2 mm × 124 mm × 10 mm formed a CD storage container. Tables 1 and 2 show various analytical values and the results of evaluation of physical properties of the recording medium storage case.

[0031]

Embodiment 3 The styrene-butadiene tapered copolymer block portion (A) constituting the styrene-butadiene block copolymer rubber is a styrene-butadiene random copolymer rubber such as US Pat. No. 3,094,512. In other words, it can be obtained by applying a production method that satisfies the relationship of polymerization rate> supply rate of styrene-butadiene mixed monomer under certain conditions. That is, polymerization is performed while supplying a monomer mixture having a desired butadiene / styrene composition ratio at a polymerization rate or lower, and then supplying a monomer mixture having a different butadiene / styrene composition ratio at a polymerization rate or lower, By repeating this operation one or more times, the styrene-butadiene tapered copolymer block (A) constituting the styrene-butadiene-based block copolymer rubber used in the present invention can be synthesized. A specific implementation method will be described. A stainless steel polymerization tank with an inner volume of 1000 L with a jacket, coil and stirrer was filled with a water content of 10 ppm.
After washing with dehydrated cyclohexane and purging with nitrogen, dehydrate to a water content of 10 ppm or less under a nitrogen gas atmosphere and cyclohexane 54 containing 139 ppm of tetrahydrofuran.
0 kg was charged into a polymerization tank, and after raising the internal temperature to 80 ° C., a cyclohexane solution containing 10 wt% of n-butyllithium was added in 0.8 ml.
kg was added.

Next, styrene dehydrated to a water content of 10 ppm or less and butadiene dehydrated by passing through a molecular sieve at a constant internal temperature of 80 ° C. are converted into six stages at a specific feed rate and polymerization time. Feeding and polymerization were carried out simultaneously while changing them. The feeding rate and the polymerization time at this time were as follows. First stage: 2.6 kg / h of styrene, 32.9 kg / h of butadiene, and 1.3 hours of polymerization time. Second stage: styrene 6.1 kg / h, butadiene 32.8 k
g / h, polymerization time 1.2 hours. Third stage: Styrene8.
7 kg / h, butadiene 25.9 kg / h, polymerization time 1.0 hour. Fourth stage: styrene 8.1 kg / h, butadiene 14.9 kg / h, polymerization time 1.0 hour. Fifth stage: styrene 8.7 kg / h, butadiene 10.5 kg
/ H, polymerization time 1.2 hours. Sixth stage: styrene 7.8
kg / h, butadiene 5.0 kg / h, polymerization time 0.9
time.

Thereafter, 45 kg of styrene dehydrated to a water content of 10 ppm or less was added at 80 ° C.
Polymerization was performed for 10 minutes at a temperature not exceeding ℃, and all of the charged styrene was polymerized. Thereafter, the polymerization solution was transferred to the next reaction vessel, water was added to 0.08 parts by weight with respect to 100 parts by weight of the polymer to stop the polymerization, and then carbon dioxide was added during the transfer to the next reaction vessel. Summed up. Next, 2,4,-
After adding bis [(octylthio) methyl] -O-cresol at a rate of 0.2% to the polymer, the solvent was removed by steam stripping and dried with a hot roll at 100 ° C. to obtain a styrene-butadiene block. A copolymer rubber was obtained. 7.9% by weight of the styrene-butadiene block copolymer rubber was dissolved in 46.6% by weight of a styrene monomer, 32.5% by weight of methyl methacrylate, 4.6% by weight of butyl acrylate, and 8.4% by weight of ethylbenzene. 100 parts by weight of the solution, 0.005 parts by weight of 1,1-bis (tert-butylperoxyl) 3,3,5-trimethylcyclohexane and 0.1 part of t-dodecyl mercaptan.
08 parts by weight of the solution was continuously fed into the first polymerization machine, and the polymerization was carried out with stirring at a polymerization temperature of 125 ° C. for an average residence time of 3 hours, followed by a residence time of 5 hours in a plug flow reactor. The whole amount was continuously charged so as to obtain a polymerization. In this way, the polymerization is carried out to a polymerization rate of 85%, and the solution is fed to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, and cut with a cutter. Thus, a pellet-shaped resin was obtained.
Next, a storage container for a CD was formed from the obtained resin with a recording medium having a thickness of 1 mm and a size of 142 mm × 124 mm × 10 mm using an injection molding machine. Tables 1 and 2 show various analytical values and the results of evaluation of physical properties of the recording medium storage case.

[0034]

Comparative Example 1 7.9% by weight of a styrene butadiene block copolymer rubber (NS-316S, manufactured by Nippon Zeon) was used in an amount of 46.6% by weight of a styrene monomer, and methyl methacrylate 3 was used.
2.5% by weight, 100% by weight of a solution of 4.6% by weight of butyl acrylate and 8.4% by weight of ethylbenzene and 1,1-bis (tert-butylperoxyl) 3;
A solution consisting of 0.005 parts by weight of 3,5-trimethylcyclohexane and 0.08 parts by weight of t-dodecylmercaptan was continuously fed into the first polymerization machine, and stirred at a polymerization temperature of 125 ° C. for an average residence time of 3 hours. After the polymerization reaction, the whole amount was continuously charged into the plug flow type reactor so that the residence time was 5 hours, and polymerization was performed. In this way, the polymerization is carried out to a polymerization rate of 85%, and the solution is fed to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, and cut with a cutter. Thus, a pellet-shaped resin was obtained. Next, the obtained resin was molded by an injection molding machine to a thickness of 1 mm and a size of 142 mm × 1.
A 24 mm × 10 mm recording medium formed a CD storage container. Tables 3 and 4 show various analytical values and the results of evaluation of the physical properties of the recording medium storage case.

[0035]

Comparative Example 2 7.9% by weight of a styrene butadiene block copolymer rubber (NS-312S manufactured by Zeon Corporation) was used in an amount of 46.6% by weight of a styrene monomer, and methyl methacrylate 3 was used.
100% by weight of a solution of 2.5% by weight, 4.6% by weight of butyl acrylate and 8.4% by weight of ethylbenzene, and 1,1-bis (tert-butylperoxyl) 3;
A solution consisting of 0.005 parts by weight of 3,5-trimethylcyclohexane and 0.08 parts by weight of t-dodecylmercaptan was continuously fed into the first polymerization machine, and stirred at a polymerization temperature of 125 ° C. for an average residence time of 3 hours. After the polymerization reaction, the whole amount was continuously charged into the plug flow type reactor so that the residence time was 5 hours, and polymerization was performed. In this way, the polymerization is carried out to a polymerization rate of 85%, and the solution is fed to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, and cut with a cutter. Thus, a pellet-shaped resin was obtained. Next, the obtained resin was molded by an injection molding machine to a thickness of 1 mm and a size of 142 mm × 1.
A 24 mm × 10 mm recording medium formed a CD storage container. Tables 3 and 4 show various analytical values and the results of evaluation of the physical properties of the recording medium storage case.

[0036]

Comparative Example 3 7.9% by weight of styrene-butadiene block copolymer rubber (670A manufactured by Nippon Elastomer Co.) was used, 46.6% by weight of styrene monomer, and methyl methacrylate 3 were used.
100% by weight of a solution of 2.5% by weight, 4.6% by weight of butyl acrylate and 8.4% by weight of ethylbenzene, and 1,1-bis (tert-butylperoxyl) 3;
A solution consisting of 0.005 parts by weight of 3,5-trimethylcyclohexane and 0.08 parts by weight of t-dodecylmercaptan was continuously fed into the first polymerization machine, and stirred at a polymerization temperature of 125 ° C. for an average residence time of 3 hours. After the polymerization reaction, the entire amount was continuously charged into the plug flow type reactor so that the residence time was 5 hours, and polymerization was performed. In this way, the polymerization is carried out to a polymerization rate of 85%, and the solution is supplied to a vented extruder to remove volatile components at 230 ° C. under reduced pressure, to draw out a molten strand from a die, water-cooled, and cut with a cutter. Thus, a pellet-shaped resin was obtained. Next, the obtained resin was molded by an injection molding machine to a thickness of 1 mm and a size of 142 mm × 1.
A 24 mm × 10 mm recording medium formed a CD storage container. Tables 3 and 4 show various analytical values and the results of evaluation of the physical properties of the recording medium storage case.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

As described above, when a resin component containing a rubber-modified aromatic vinyl copolymer resin using a rubber-like polymer having a specific structure as an essential component is used, recording having excellent impact strength and transparency is achieved. A medium storage case is obtained. In addition, this case is used for CDs and DVDs that store high-density and high-capacity information.
It is most suitable as a storage case for recording media.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // C08L 51:04 C08L 51:04 (72) Inventor Takeshi Otsuka 3-5-1 Asahimachi, Machida-shi, Tokyo Electrochemistry F-term in the Central Research Laboratory of Industry Co., Ltd. (reference)

Claims (3)

[Claims] 1. A rubber-modified aromatic vinyl copolymer resin containing a rubbery polymer as dispersed particles in a continuous matrix resin, wherein (1) the continuous matrix has a refractive index substantially equal to that of the rubbery polymer. Having a structural unit of 20 to 80% by weight of at least one aromatic vinyl compound and at least one alkyl (meth) acrylate compound 20 to
A mixed solution consisting of 80% by weight is copolymerized,
(2) The content of the rubbery polymer is 3 to 20% by weight based on the rubber-modified aromatic vinyl copolymer resin, and (3) the average particle diameter of the rubbery polymer dispersed particles is 0.3 to (4) and the glass transition point of the dispersed particles is -75.
A recording medium storage case comprising a resin composition containing a rubber-modified aromatic vinyl copolymer resin in a temperature range of from -30 ° C to -30 ° C. 2. A block part (A) in which a rubbery polymer is composed of a random or tapered copolymer of styrene and butadiene and a styrene butadiene copolymer block part in which a styrene homopolymer or a major part is composed of styrene. 2. The recording medium storage case according to claim 1, wherein the case is a block copolymer comprising (B). 3. The aromatic vinyl compound is styrene,
3. The recording medium storage case according to claim 1, wherein the alkyl (meth) acrylate compound is methyl methacrylate alone or a mixture of methyl methacrylate and butyl acrylate.