JP2011184474A - Resin composition excellent in aqueous ink printability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly-versatile styrenic resin having good adhesiveness with an aqueous ink, and also good mechanical strength such as tensile elastic modulus. <P>SOLUTION: A thermoplastic resin composition comprises 90-98 mass% of a thermoplastic resin (1), and 2-10 mass% of a copolymer (2) composed of 50-95 mass% of a vinyl aromatic hydrocarbon and 5-50 mass% of glycidyl (meth)acrylate, wherein the thermoplastic resin (1) is at least one selected from the group consisting of: (a) a block copolymer composed of a polymer block A having at least one vinyl aromatic hydrocarbon as a main substance and a polymer block B having at least one conjugated diene, and having a content of the vinyl aromatic hydrocarbon of 40-95 mass%, or a hydrogenated product thereof; and (b) at least one thermoplastic resin selected from the group consisting of a block copolymer resin, having a structure different from (a), of a conjugated compound and a vinyl aromatic compound, a vinyl aromatic compound polymer resin, and a copolymer resin of a vinyl aromatic compound and another vinyl monomer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin composition excellent in printability of water-based ink.

Styrenic resins are used as packaging materials for sheets, films, and the like, but images such as letters and designs are printed with organic solvent-based inks or the like in order to improve design properties.
On the other hand, in the printing industry that performs gravure printing and the like, there is an increasing tendency to refrain from using organic solvent-based inks from the viewpoint of preventing environmental pollution caused by the release of organic solvents and improving the working environment.

  In addition, when used in food packaging packs and films, water-based inks are increasingly used in place of organic solvent-based printing inks from the viewpoint of being unfavorable for hygiene when organic solvents and the like migrate to foods. .

  As a technique for improving the printability of a resin, a technique for introducing an epoxy group into the resin has been studied. For example, in Reference 1, a graft copolymer comprising an olefin polymer and a vinyl polymer containing an epoxy group is used. As a composition of styrene and a thermoplastic resin, Reference 2 discloses a composition in which a vinyl chloride resin is mixed with a copolymer of glycidyl methacrylate and a long chain methacrylate at a high concentration.

Japanese Patent Laid-Open No. 5-78549 JP-A-11-343375

  However, styrene resins having poor wettability than the above resins have poor adhesion to water-based inks by gravure printing, and styrene resins having good printability while maintaining mechanical strength have not yet been obtained.

  Therefore, in the present invention, in view of the above-mentioned problems of the prior art, it is intended to provide a highly versatile resin composition that has good adhesion to water-based ink and good mechanical strength such as tensile elastic modulus. Objective.

As a result of intensive studies to solve the above problems, the present inventors have found that the specific thermoplastic resin (1) is 90 to 98% by mass, the vinyl aromatic hydrocarbon is 50 to 95% by mass, and glycidyl (meth) acrylate. The present inventors have found that a thermoplastic resin composition containing 2 to 10% by mass of a copolymer (2) composed of 5 to 50% by mass can solve the above-mentioned problems, and has completed the present invention.
That is, the present invention is as follows.

[1] 90 to 98% by mass of thermoplastic resin (1), 50 to 95% by mass of vinyl aromatic hydrocarbon and 2 to 10% by mass of copolymer (2) consisting of 5 to 50% by mass of glycidyl (meth) acrylate %, A thermoplastic resin composition comprising
The thermoplastic resin composition, wherein the thermoplastic resin (1) is at least one selected from the group consisting of the following (a) and (b).
(A) It comprises a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B having at least one conjugated diene, and has a vinyl aromatic hydrocarbon content of 40 to 95% by mass. (B) A block copolymer resin of a conjugated diene compound and a vinyl aromatic compound different from (a), a vinyl aromatic compound polymer resin, a vinyl aromatic compound and other At least one thermoplastic resin comprising a group selected from copolymer resins with vinyl monomers

[2] The thermoplastic resin composition according to claim 1, wherein the copolymer (2) contains 70 to 95% by mass of vinyl aromatic hydrocarbon and 5 to 30% by mass of glycidyl (meth) acrylate.

[3] The thermoplastic resin composition according to claim 1, wherein the (co) polymer resin (b) has a weight average molecular weight (Mw) of 5 to 200,000.

[4] A thermoplastic resin sheet formed by molding the resin composition according to any one of claims 1 and 2.

[5] A thermoplastic resin film formed by molding the resin composition according to any one of claims 1 and 2.

  According to the present invention, it is possible to provide a highly versatile styrenic resin that has good adhesion to water-based inks and good mechanical strength such as tensile elastic modulus.

  Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the present embodiment, and can be implemented with various modifications within the scope of the gist.

  First, a block copolymer comprising at least one polymer block A mainly composed of a vinyl aromatic hydrocarbon and at least one polymer block B having a conjugated diene as the thermoplastic resin (1) or the same The hydrogenated product (1) (hereinafter also referred to as the block copolymer (1) and the hydrogenated product (1) of the block copolymer, respectively) will be described.

  The polymer block A mainly composed of vinyl aromatic hydrocarbon is a copolymer block of vinyl aromatic hydrocarbon and conjugated diene containing 50% by mass or more of vinyl aromatic hydrocarbon, or vinyl aromatic hydrocarbon alone The polymer block of is shown.

  The polymer block B containing a conjugated diene indicates a copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon containing the conjugated diene in an amount exceeding 10% by mass, or a polymer block of a conjugated diene alone.

  When a random copolymer block of vinyl aromatic hydrocarbon and conjugated diene is present in polymer block A mainly composed of vinyl aromatic hydrocarbon or polymer block B mainly composed of conjugated diene, The vinyl aromatic hydrocarbons may be distributed uniformly in the random copolymer block or may be distributed in a tapered shape. The copolymer block may have a plurality of portions where vinyl aromatic hydrocarbons are uniformly distributed and / or portions where tapes are distributed.

  When the modified block copolymer of the present embodiment has a plurality of polymer blocks A (or B), they may be different in molecular weight, composition, type, and the like.

The block copolymer (1) can be basically synthesized by a conventionally known method.
For example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17879, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 57-49567, Japanese Patent Publication No. 58-11446, etc. Can be synthesized by a block copolymerization method of a conjugated diene and a vinyl aromatic hydrocarbon using an anionic initiator such as an organolithium compound in a hydrocarbon solvent. However, in this Embodiment, the manufacturing conditions of each constituent polymer shall be set as described later.

Examples of the polymer structure of the block copolymer (1) include linear block copolymers such as the following (a) to (c).
A- (BA) n (a)
A- (B-A) n-B (b)
B- (A-B) n + 1 (c)
Here, A is a polymer block mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block mainly composed of conjugated dienes. The boundary between the A block and the B block does not necessarily have to be clearly distinguished. n is an integer greater than or equal to 1, and is generally 1-5.

Moreover, as a polymer structure of a block copolymer (1), the radial block copolymer like following (d)-(g) other than the said linear block copolymer is mentioned.
[(A−B) k] m−X (d)
[(A−B) k−A] m−X (e)
[(B−A) k] m−X (f)
[(B−A) k−B] m−X (g)

  Here, A and B are synonymous with the above (a) to (c), k is an integer of 1 or more, m is an integer of 3 or more, and generally 3 to 5. The polymer in which m is 3 to 5 may include a polymer in which m is 1 and / or 2. X represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride or a residue of an initiator such as a polyfunctional organolithium compound.

  Examples of the vinyl aromatic hydrocarbon include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, 1,1. -Diphenylethylene and the like can be mentioned. Among them, styrene is preferable because of its good reactivity and high strength. These may use only 1 type and may mix and use 2 or more types.

The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, 1,3-hexadiene,
1,3-butadiene and isoprene are preferred. These may use only 1 type and may mix and use 2 or more types.

  When 1,3-butadiene and isoprene are used in combination as the conjugated diene, the proportion of isoprene is preferably 10% by mass or more and 25% by mass or more with respect to the total mass of 1,3-butadiene and isoprene. More preferably, it is more preferably 40% by mass or more. If the isoprene content is 10% by mass or more, it is difficult to cause thermal decomposition during molding at a high temperature and the molecular weight does not decrease. Therefore, a modified block copolymer having a good balance between appearance characteristics and mechanical strength and composition thereof Tends to be obtained.

  In the step of synthesizing the block copolymer (1), a hydrocarbon solvent is used. Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, and octane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; benzene, Aromatic hydrocarbons such as toluene, ethylbenzene and xylene can be used. These may use only 1 type and may mix and use 2 or more types.

In the step of synthesizing the block copolymer (1), an anionic initiator is used. Examples of the anionic initiator include organic monolithium compounds, organic dilithium compounds, and organic polylithium compounds in which one or more lithium atoms are bonded in the molecule.
Specific examples include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, and isoprenyl dilithium. . These may use only 1 type and may mix and use 2 or more types.

In the step of synthesizing the block copolymer (1), the polymerization rate is adjusted, the microstructure of the polymerized conjugated diene part (the ratio of cis, trans, vinyl), the reaction ratio of the conjugated diene and the vinyl aromatic hydrocarbon A polar compound or a randomizing agent can be used for the purpose of adjustment.
Examples of polar compounds and randomizing agents include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether; amines such as triethylamine and tetramethylethylenediamine; thioethers; phosphines; phosphoramides; alkylbenzene sulfonates; Examples thereof include sodium alkoxide.

The polymerization temperature condition of the block copolymer (1) is generally in the range of −10 ° C. to 150 ° C., preferably in the range of 40 ° C. to 120 ° C.
The time required for polymerization varies depending on the conditions, but in general, it can be carried out within 48 hours, and can be carried out in 1 to 10 hours by selecting particularly good conditions.
Moreover, it is preferable that the atmosphere of the system at the time of the polymerization is in a state where it is substituted with an inert gas such as nitrogen gas.
The pressure at the time of carrying out the polymerization is not particularly limited as long as it is in a range sufficient to maintain the monomer and solvent in the liquid layer within the above polymerization temperature range.
Furthermore, care should be taken not to mix impurities, such as water, oxygen, carbon dioxide, etc., that inactivate the catalyst and living polymer into the polymerization system.

  The vinyl aromatic hydrocarbon content in the block copolymer (1) is preferably in the range of 40 to 95% by mass, more preferably in the range of 50 to 95% by mass, and still more preferably in the range of 70 to 95% by mass. It is a range. When the vinyl aromatic hydrocarbon content in the block copolymer (1) is in the range of 40 to 95% by mass, a resin having excellent impact resistance and rigidity balance performance and excellent transparency can be obtained. It is in.

  The block ratio of the vinyl aromatic hydrocarbon polymer block incorporated in the block copolymer (1) is preferably in the range of 50 to 100%. It is preferable for the block ratio of the vinyl aromatic hydrocarbon polymer block to be 50% or more because excellent rigidity tends to be obtained in the modified block copolymer and the resin composition thereof in the present embodiment.

The block ratio of the vinyl aromatic hydrocarbon polymer block is the mass of the vinyl aromatic hydrocarbon and the conjugated diene in the process of copolymerizing at least a part of the vinyl aromatic hydrocarbon and the conjugated diene during the production of the block copolymer. It can be controlled by adjusting the mass ratio, the polymerization reactivity ratio, and the like.
Specifically, (a) a mixture of a vinyl aromatic hydrocarbon and a conjugated diene is continuously supplied to the polymerization system for polymerization, and / or (b) a polar compound or a randomizing agent is used. And a method of copolymerizing vinyl aromatic hydrocarbon and conjugated diene.

  Examples of the polar compound or randomizing agent include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine; thioethers; phosphines; phosphoramides; alkylbenzene sulfonates; And sodium alkoxide.

The block ratio of the aromatic hydrocarbon polymer block is a method of oxidatively decomposing a block copolymer with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1
, 429 (1946)] is quantified with the vinyl aromatic hydrocarbon polymer block component (excluding vinyl aromatic hydrocarbon polymer components having an average degree of polymerization of about 30 or less). , Using the following formula.

Vinyl aromatic of block copolymer (1)
Mass% of hydrocarbon polymer block
Block rate (%) = ――――――――――――――――― × 100
Total vinyl of block copolymer (1)
% By mass of aromatic hydrocarbon

  The number average molecular weight (Mn) of the vinyl aromatic hydrocarbon polymer block in the block copolymer (1) is preferably in the range of 10,000 to 150,000, and more preferably in the range of 20,000 to 120,000. When the (Mn) is 10,000 or more and 150,000 or less, there is a tendency that even more excellent rigidity and impact resistance are obtained, and further, molding processability and transparency tend to be good.

The number average molecular weight (Mn) is obtained by oxidatively decomposing a block copolymer with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1, 429 (1946)] from the vinyl aromatic hydrocarbon polymer block component obtained by gel permeation chromatography (GPC).
That is, GPC measurement of monodisperse polystyrene for GPC is performed, a calibration curve is created between the peak count number and the molecular weight of the monodisperse polystyrene, and calculation is performed according to a conventional method (for example, “Gel Chromatography <Basics> Issued by Kodansha”). can do.

  The value of the melt flow rate (MFR) of the polymer block A mainly composed of vinyl aromatic hydrocarbons is preferably 2 to 35 g / 10 minutes, and more preferably 3 to 25 g / 10 minutes in terms of moldability. In the present embodiment, the value of MFR (melt flow rate) is a value obtained by measurement under the conditions of 200 ° C. and a load of 5 kgf by the method defined in JIS K7210 (Method A).

Next, a hydrogenated block copolymer (1) containing at least one polymer block A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B mainly composed of conjugated diene. ).
The block copolymer hydrogenated product (1) is obtained by subjecting the block copolymer (1) obtained above to hydrogenation (hereinafter also abbreviated as “hydrogenated”). .

The hydrogenation catalyst used in the hydrogenation is not particularly limited, and conventionally known catalysts, for example, (1) metals such as Ni, Pt, Pd, and Ru are supported on carbon, silica, alumina, diatomaceous earth, and the like. Supported so-called heterogeneous hydrogenation catalyst, (2) so-called Ziegler-type hydrogenation using an organic acid salt such as Ni, Co, Fe, Cr, or a transition metal salt such as acetylacetone salt and a reducing agent such as organic aluminum A catalyst, (3) a homogeneous hydrogenation catalyst such as a so-called organometallic complex, such as an organometallic compound such as Ti, Ru, Rh, or Zr, can be applied.
Specifically, JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041 Can be applied.

Preferable examples of the hydrogenation catalyst include a mixture of a titanocene compound and a reducing organometallic compound.
As the titanocene compound, for example, a compound described in JP-A-8-109219 can be used. Specific examples include (substituted) such as biscyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride. And compounds having at least one ligand having a cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton.
Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

The temperature condition for carrying out the hydrogenation reaction on the block copolymer is preferably in the range of 0 to 200 ° C, more preferably in the range of 30 to 150 ° C.
The pressure of hydrogen used for the hydrogenation reaction is preferably 0.1 to 15 MPa, more preferably 0.2 to 10 MPa, and still more preferably 0.3 to 5 MPa.
The hydrogenation reaction time is preferably 3 minutes to 10 hours, more preferably 10 minutes to 5 hours.
The hydrogenation reaction can be performed by a batch process or a continuous process, and these may be performed alone or in combination.

In the hydrogenated block copolymer (1), the hydrogenation rate of the unsaturated double bond based on the conjugated diene compound is not particularly limited, but is preferably 70% or more, more preferably 80% or more. More preferably, 90% or more is hydrogenated, and the unsaturated double chain is incorporated in the block copolymer in a 1,2-bond, 3,4-bond, or 1,4-bond bond mode. Only some of the bonds may be hydrogenated. When only a part is hydrogenated, the hydrogenation rate is preferably 10% or more and less than 70%, more preferably 15% or more and less than 65%, and more preferably 20% or more and less than 60%. Further preferred.
Furthermore, in the hydrogenated product (1) of the block copolymer, the hydrogenation rate of the vinyl bond based on the conjugated diene before hydrogenation is preferably 85% or more, more preferably 90% or more. And more preferably 95% or more. By setting the hydrogenation rate within the above range, the thermal stability tends to be improved.
In addition, the hydrogenation rate of the said vinyl bond means the ratio of the vinyl bond hydrogenated among the vinyl bonds based on the conjugated diene before hydrogenation incorporated in the block copolymer.

In the hydrogenated product (1) in the block copolymer, the hydrogenation rate of the aromatic double bond based on the vinyl aromatic hydrocarbon is not particularly limited, but is preferably 50% or less. % Or less, more preferably 20% or less.
The hydrogenation rate and the vinyl bond amount based on the conjugated diene compound can be measured by a nuclear magnetic resonance apparatus (NMR).
The resin composition (a) is obtained by blending at least one component selected from other thermoplastic resins into the block copolymer or the hydrogenated product thereof.
The resin composition (a) in the present invention includes the case of only the above-mentioned block copolymer or hydrogenated product thereof.
The composition ratio of the block copolymer or the hydrogenated product thereof to other thermoplastic resins is preferably 25/75 to 100/0 for the block copolymer or the hydrogenated product / other thermoplastic resins. / 60 to 70/20 is more preferable.

The thermoplastic resin (component b) used as the other resin is not particularly limited, but the following thermoplastic resins can be used.
For example, a block copolymer resin of a conjugated diene compound and a vinyl aromatic compound having a structure different from that of the modified block copolymer described above or a hydrogenated product thereof, a vinyl aromatic compound polymer resin such as polystyrene, a vinyl aromatic Group compounds and other vinyl monomers (eg, ethylene, propylene, butylene, vinyl acetate, acrylic acid esters such as acrylic acid and acrylic methyl, methacrylic acid esters such as methacrylic acid and methyl methacrylate, acrylonitrile, methacrylonitrile, etc.) The copolymer resin of these is mentioned.

  Other than the above, rubber-modified styrene resin (HIPS), acrylonitrile-butadiene-styrene copolymer resin (ABS), and methacrylic acid ester-butadiene-styrene copolymer resin (MBS) may be mentioned.

1000 or more are preferable, as for the number average molecular weight of these thermoplastic resins, 5000-5 million are more preferable, and 10,000-1 million are still more preferable.
In addition, the said thermoplastic resin may be used independently and may use 2 or more types together.
Among these resins, those obtained with transparency include block copolymer resins of conjugated diene compounds and vinyl aromatic compounds, vinyl aromatic compound polymer resins such as polystyrene, vinyl aromatic compounds and (meth) acrylic. A copolymer resin with an acid ester is particularly preferred.
The component (b) used in the present invention is a vinyl aromatic hydrocarbon in consideration of good dispersibility with the polymer block A mainly composed of the vinyl aromatic hydrocarbon of the component (a) and adhesiveness with aqueous ink. And a copolymer of glycidyl (meth) acrylate. The vinyl aromatic hydrocarbon content is preferably 50 to 95 mass%, more preferably 70 to 95 mass%, further preferably 85 to 95 mass%, and the content of glycidyl (meth) acrylate is preferably 5 to 50 mass%. 5 to 30% by mass is more preferable because uniform compatibility is obtained, and 5 to 15% by mass is more preferable because a molded article having a more beautiful appearance can be obtained. For the same reason, the weight average molecular weight is preferably 5,000 to 300,000, more preferably 50,000 to 200,000, and 50,000 to 100,000 have good adhesion to water-based ink, and the balance between rigidity and elongation is also good. Since it is obtained, it is more preferable.
It does not restrict | limit especially about the method of manufacturing the block copolymer composition mentioned above, A well-known method can be utilized.
For example, a melt kneading method using a general mixer such as an open roll, a Banbury mixer, a single screw extruder, a twin screw extruder, a kneader, a multi-screw extruder, etc., after dissolving or dispersing and mixing each component, A method of removing the solvent by heating can be applied. In particular, a melt kneading method using an extruder is preferable from the viewpoints of productivity and good kneading properties.

  The melt kneading temperature takes into consideration the melting point, melt viscosity, block copolymer or hydrogenated product (1) thereof, and thermal degradation of the primary modified block copolymer or hydrogenated product (2) thereof. And 100-350 degreeC is preferable, 150-350 degreeC is more preferable, and 180-330 degreeC is still more preferable.

  The melt kneading time (or the average residence time of the melt kneading step) is the degree of kneading (dispersibility), productivity, block copolymer or hydrogenated product (1), and primary modified block copolymer or water thereof. In consideration of deterioration of the additive (2), the thermoplastic resin, etc., 0.2 to 60 minutes is preferable, 0.5 to 30 minutes is more preferable, and 1 to 20 minutes is still more preferable.

The resin composition of the present invention is a known method generally used for molding thermoplastic resins, for example, injection molding, T-die, extrusion molding such as profile extrusion, blow molding, vacuum molding, inflation molding, tenter, stretcher. It can shape | mold by methods, such as film shaping | molding by the extending | stretching process by, and sheet | seat shaping | molding. The shape of the molded body is not particularly limited, and may be, for example, a film shape or a sheet shape.
In particular, when forming by stretching, it is desirable that the resin composition of the present invention can be used to form a film with little thickness unevenness during stretching.

  Moreover, a laminated body can be obtained by forming the surface layer which consists of the resin composition of this invention in the single side | surface of the base material layer which consists of thermoplastic resins. The method for forming the surface layer composed of the resin composition of the present invention on one side of the base layer of the thermoplastic resin is not particularly limited, and is a method used for general multilayer molding, for example, two-color molding method in injection molding, multilayer Examples thereof include a method using a T die, a method in which a surface film or sheet is prepared in advance and bonded or heat-sealed, and a method of bonding via an adhesive layer. Thus, by forming the surface layer made of the resin composition of the present invention, it is possible to obtain a molded article having various mechanical performances and excellent in printability of aqueous ink.

Hereinafter, the present invention will be described with reference to specific examples and comparative examples.
The physical property measurement methods and evaluation methods applied to the examples and comparative examples are shown below.

(A) Composition and structural evaluation of vinyl aromatic copolymer (1) Styrene content of vinyl aromatic hydrocarbon copolymer Calculated from an absorption intensity of 262 nm using an ultraviolet spectrophotometer (Hitachi UV200). .

(2) Styrene Block Ratio of Vinyl Aromatic Hydrocarbon Copolymer A Method of Oxidative Decomposition of Block Copolymer with Di-tert-Butyl Hydroperoxide Using Osmium Tetroxide as a Catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1,429 (1946)] was quantified and determined from the following formula.

(P-1) to (P-9) each vinyl aromatic
Mass% of hydrocarbon polymer block
Styrene block ratio (%) = ――――――――――――――――― × 100
(P-1) to (P-9) All vinyls
% By mass of aromatic hydrocarbon

(3) Melt flow rate Based on ASTM D1238, it was measured under the conditions of 200 ° C. and a load of 5 kg.

(4) Weight average molecular weight Using a GPC apparatus (HLC8220GPC; manufactured by Tosoh Corporation), tetrahydrofuran was used as a solvent, and measurement was performed at a column temperature of 40 ° C.
The weight average molecular weight was determined from a calibration curve prepared using a commercially available standard polystyrene having a known weight average molecular weight and number average molecular weight.

(5) Preparation of sample for evaluation In the hopper of Ikekai Co., Ltd. T-die mounting extruder (FS40-36V type / barrel diameter 40mmφ, L / D = 36, width 400mm T-die mounting, 2-stage dull mage screw) Each raw material pellet was charged with the formulation shown in 3).
The obtained sheet was stretched 5 times at 85 ° C. by using a tenter stretching device (SF-625) manufactured by Ichikin Kogyo Co., Ltd. to produce a stretched film having a width of 1 m.
About the obtained sheet | seat and a stretched film, based on the method described in the following item, the tensile elasticity modulus, the wetting index, the adhesiveness with water-based ink, and the thickness precision of the stretched film were measured.

(6) Tensile modulus Based on ASTM D638, the tensile modulus was measured at a test speed of 5 mm / min using a TG-5KN type tester manufactured by Minebea Co., Ltd.

(7) Wetting index Measured with a wetting index reagent in accordance with JIS K6768.

(8) Adhesiveness with water-based ink Using a gravure mini proofing machine (manufactured by Nissho Gravure Co., Ltd.), water-based gravure ink (Super Eco Pure: Sakata Inx Co., Ltd.) is used. Were blended at a mass ratio of Super Eco Pure / Thinning Solution = 100/50, and the surface of the produced resin sheet was printed. The coating film adhesion was evaluated by a cross-cut method based on JIS 5400 and 5600, and the adhesion to the aqueous gravure ink was evaluated.
The printed resin sheet is allowed to stand at 23 ° C. for 24 hours, and scratches are made with a blade so that the surface printed with ink becomes 100 squares at 1 mm intervals, and Nichiban adhesive tape (CT-18 or LP-18) , Adhesive force 4.01 N / cm) was adhered, and the printed surface was peeled off instantaneously in an angle direction of 30 degrees. The number of printing inks peeled off was determined as follows.
○: 0/100 (complete adhesion) or more and less than 20/100,
Δ: 20/100 or more and less than 50/100 x: 50/100 or more and 100/100 or less

(9) The haze sheet was based on JIS K7105, and a haze meter (1001DP) manufactured by Nippon Denshoku Co., Ltd. was used.
The quality of haze was determined as follows.
◯: Less than 30% Δ: 30% or more to less than 50% ×: 50% or more

(10) Thickness accuracy of stretched film The stretched film was cut parallel to the stretching direction, the thickness was measured every 5 cm from the end, and the difference between the maximum thickness and the minimum thickness was calculated.

Next, each component used in Examples and Comparative Examples is shown below.
(B) Raw materials used (1) Block copolymer (P-1)
Using an autoclave equipped with a stirrer, under a nitrogen gas atmosphere i) 0.080 parts by mass of n-butyllithium was added to a cyclohexane solution containing 25 parts by mass of styrene, and polymerization was performed at 80 ° C. for 20 minutes.
Next, ii) a cyclohexane solution containing 14 parts by mass of styrene and 32 parts by mass of 1,3-butadiene was continuously added for 60 minutes to polymerize at 80 ° C.
Next, iii) A cyclohexane solution containing 29 parts by mass of styrene was continuously added for 25 minutes and polymerized at 80 ° C., and then kept at 80 ° C. for 10 minutes. Thereafter, the polymerization was stopped by adding methanol to the polymerization vessel at a 0.9-fold mole relative to n-butyllithium, and 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) was used as a stabilizer. ) Ethyl] -4,6-di-t-pentylphenyl acrylate is added to 0.5 part by mass with respect to 100 parts by mass of the block copolymer, and then the solvent is removed to obtain the block copolymer (a-1). Obtained. Block copolymer a-1 is polymer block A having a styrene / 1,3-butadiene = 100/0 mass ratio, polymer block B having a styrene / 1,3-butadiene = 30/70 mass ratio, and styrene. / A, 3-butadiene is an ABA block polymer composed of polymer block A with a mass ratio of 100/0. The obtained block copolymer a-1 has a number average molecular weight of 85,000, a styrene content of 70% by mass, a block rate of 80% by mass, and a melt flow rate of 6 g / 10 min (according to ASTM D1238, 200 ° C., load 5 kg).

(2) Block copolymer (P-2 to P-5)
Using the same method as for the block copolymer (P-1), the addition amount of styrene and 1,3-butadiene added in i), ii) and iii) of (P-1), and n-butyllithium A block copolymer (P-2 to P-5) was prepared by appropriately controlling the amount of addition.
In addition, when the addition amount of n-butyl lithium is decreased, the molecular weight is increased. When the amount of styrene added in ii) is increased with respect to the amount of styrene added in i) and iii), the styrene block rate decreases.
Table 1 below shows the styrene content, styrene block ratio, and melt flow rate of the block copolymers (P-1) to (P-5) produced as described above.

(3) Polystyrene resin As the thermoplastic resin, polystyrene 685 (manufactured by PS Japan Co., Ltd.) and a styrene-butyl acrylate copolymer (polystyrene SC004 produced by PS Japan Co., Ltd.) were used.

(4) Polyvinyl chloride resin Shin-Etsu Chemical Co., Ltd .: TK-800 mixed with 6 parts by weight of dioctyl phthalate (DOP) was used. (In the table of examples, the DOP formulation is described as TK-800 on the title)

(5) Glycidyl group-containing copolymer As a glycidyl methacrylate copolymer, NOF CORPORATION, Marproof G series was used. (GMA1-GMA6)
The trade name, the glycidyl methacrylate content, the copolymerization partner monomer with glycidyl methacrylate, and the weight average molecular weight are listed in (Table 2).

[Example 1-10 and Comparative Example 1-8]
The results are shown in (Table 3).

Example 1 which is a composition using a block copolymer (P-1) to (P-5) in the present embodiment, a copolymer comprising a vinyl aromatic hydrocarbon having a specific structure and glycidyl (meth) acrylate. No. 10 is excellent in mechanical strength, and the wetting index is equivalent to that in Comparative Examples 1 to 6, but the adhesiveness with the water-based ink is also good.
Further, when vinyl aromatic hydrocarbon and glycidyl methacrylate copolymer are blended with polyvinyl chloride, the thickness accuracy of the stretched film deteriorates (Comparative Example 7 and Comparative Example 8), whereas the block copolymer of the present invention When the blend of the vinyl aromatic hydrocarbon and the glycidyl methacrylate copolymer was mixed with the coalescence, the film thickness accuracy was improved. (Examples 1-10, Comparative Example 1, Comparative Examples 5-6)

  The modified block copolymer of the present invention is excellent in adhesion strength with water-based ink, and has industrial applicability as a heat-shrinkable film to be covered on a packaging film, a beverage container or the like, and various sheet materials.

Claims (5)

90 to 98% by mass of thermoplastic resin (1), 50 to 95% by mass of vinyl aromatic hydrocarbon and 2 to 10% by mass of copolymer (2) consisting of 5 to 50% by mass of glycidyl (meth) acrylate A thermoplastic resin composition comprising:
The thermoplastic resin composition, wherein the thermoplastic resin (1) is at least one selected from the group consisting of the following (a) and (b).
(A) It comprises a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B having at least one conjugated diene, and has a vinyl aromatic hydrocarbon content of 40 to 95% by mass. (B) (a) is a block copolymer resin of a conjugated diene compound and a vinyl aromatic compound, vinyl aromatic compound polymer resin, vinyl aromatic compound and others At least one thermoplastic resin consisting of a group selected from copolymer resins with other vinyl monomers   The thermoplastic resin composition according to claim 1, wherein the copolymer (2) has a vinyl aromatic hydrocarbon content of 70 to 95% by mass and glycidyl (meth) acrylate of 5 to 30% by mass.   The thermoplastic resin composition according to claim 1, wherein the (co) polymer resin (b) has a weight average molecular weight (Mw) of 5 to 200,000.   A thermoplastic resin sheet formed by molding the resin composition according to claim 1.   A thermoplastic resin film formed by molding the resin composition according to claim 1.