JP2007291264A - Resin composition for heat-shrinkable film, heat-shrinkable film, and bottle wrapped around the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition capable of shrinking at a low temperature and providing a heat-shrinkable film that is appropriate without shrinkage gradient being too high and excellent in bottle shape retention, and processing the resin composition for heat-shrinkable film A heat-shrinkable film, and a bottle wrapped with the film.
SOLUTION: A styrene- (meth) acrylic copolymer (A) and a block copolymer (B) having a styrene polymer block (b1) and a conjugated diene polymer block (b2) are contained. A heat-shrinkable film, which is a resin composition, wherein the styrene- (meth) acrylic copolymer (A) contains a multi-branched styrene- (meth) acrylic copolymer (a1). A resin composition for heat treatment, a heat-shrinkable film obtained from the resin composition for heat-shrinkable film, and a bottle characterized by winding the heat-shrinkable film.
[Selection figure] None

Description

  The present invention is particularly excellent in shape retention of thin and light PET bottles, and can provide a film having heat shrinkability and transparency suitable as a shrink label for packaging the bottle, The present invention relates to a heat-shrinkable film obtained from the composition and a bottle around which the film is wound.

  The heat-shrinkable film is widely used as a shrink label for the purpose of improving the design properties of beverage bottles such as PET bottles and glass bottles. Previously, vinyl chloride resin-based shrink films were frequently used due to heat shrinkability, strength, printability, and good finish after shrinkage, but in recent years there is a possibility that vinyl chloride resin may generate dioxins during combustion. Therefore, most of the shrink labels for beverage bottles in Japan have been replaced with styrene resin films or PET films, and in particular, the demand for styrene resin films is high due to low temperature shrinkage and good finish after shrinkage.

  In recent years, the aseptic filling method that fills the contents at room temperature with a completely aseptic line is on the rise, there is no need to heat-treat the PET bottle, and the viewpoint of reducing the burden of the container recycling method and suppressing the depletion of petroleum resources, etc. Therefore, non-heat-resistant PET bottles are becoming thinner and lighter. As a result, the shrink label for PET bottles has a low temperature shrinkage of about 5 to 10 ° C., in some cases 10 ° C. or more, and a wide shrinkage temperature range, that is, a shrinkage gradient (in the heat shrink curve). The amount of change in shrinkage with respect to temperature is not abrupt).

  In response to the above requirements, the present applicant has already assumed that both low-temperature shrinkage and transparency have been achieved, and two specific styrene copolymers having different glass transition temperatures and styrene-conjugated diene copolymers. A resin composition for a low-temperature shrinkable film mixed with a polymer has been proposed (see, for example, Patent Document 1). However, when the film obtained from the composition is applied to the aforementioned thin-walled lightweight PET bottle, it is inferior in “bottle shape retention” that suppresses deformation of the bottle, so when discharged from a vending machine, a serpentine column (bottle Due to the drop load of the upper bottle filled in a dozen or more bottles, the shape of the bottle that should be stopped by the bend mech (stopper for discharging one bottle at a time) is deformed. There is a problem that a large number of remaining bottles are discharged all at once, and a solution is eagerly desired.

JP 2005-036057 A

  In view of the above situation, the problem to be achieved by the present invention is a resin composition that can shrink at a low temperature, has a shrinkage gradient that is not too high, is appropriate, and provides a heat-shrinkable film excellent in bottle shape retention. An object of the present invention is to provide a heat-shrinkable film obtained by processing the resin composition for heat-shrinkable film, and a bottle around which the film is wound.

  As a result of intensive studies to solve the above problems, the present inventors have found that a styrene- (meth) acrylic copolymer including a multi-branched styrene- (meth) acrylic copolymer, and a styrene polymer It has been found that a resin composition containing a block and a block copolymer having a conjugated diene polymer block is excellent in low-temperature shrinkage, has an appropriate shrinkage gradient, and is particularly excellent in the aforementioned bottle shape retainability. It came to complete.

  That is, the present invention provides a styrene- (meth) acrylic copolymer (A), a block copolymer (B) having a styrene polymer block (b1) and a conjugated diene polymer block (b2). A heat-shrinkable resin composition comprising the styrene- (meth) acrylic copolymer (A) containing a multi-branched styrene- (meth) acrylic copolymer (a1). The resin composition for adhesive films, the heat-shrinkable film obtained by processing the resin composition, and the bottle around which the film is wound are provided.

  INDUSTRIAL APPLICABILITY The present invention provides a resin composition that can be shrunk at a low temperature, has an appropriate shrinkage gradient without being too high, and provides a heat-shrinkable film excellent in bottle shape retention, and shrinkage formed by processing the resin composition An adhesive film and a bottle around which the film is wound can be provided.

  The resin composition for heat-shrinkable film of the present invention comprises a block copolymer having a styrene- (meth) acrylic copolymer (A), a styrene polymer block (b1), and a conjugated diene polymer block (b2). It is a resin composition containing a polymer (B), and the styrene- (meth) acrylic copolymer (A) includes a multi-branched styrene- (meth) acrylic copolymer (a1). It is characterized by this. The heat-shrinkable film of the present invention is obtained by stretching the resin composition.

  The styrene- (meth) acrylic copolymer (A) is a multi-branched styrene- (meth) acryl to achieve low temperature shrinkage, proper shrinkage gradient, and high bottle shape retention, which are the problems of the present invention. It is essential to contain the system copolymer (a1).

  That is, the styrene- (meth) acrylic copolymer (A) includes a multi-branched styrene- (meth) acrylic copolymer (a1) and a linear styrene- (meth) having no multi-branched structure. It consists of an acrylic copolymer (a2). When the molecular weight of this copolymer (A) is measured by GPC-MALLS (multi-angle light scattering detector), the peak derived from the multi-branched styrene- (meth) acrylic copolymer is on the high molecular weight side, and the multi-branched structure The peak derived from the linear styrene- (meth) acrylic copolymer (a2) not having a molecular weight appears on the low molecular weight side, the composition ratio of both copolymers from the area ratio of both peaks, and the respective copolymers And the weight average molecular weight of the copolymer (A) can be determined. The weight average molecular weight described below is a value measured by GPC-MALLS. In GPC-MALLS, the relationship between the weight average molecular weight and the radius of inertia can also be obtained. The calculation of the radius of inertia is described in, for example, characterization of polymers and fine particles (Shoko Tsusho Co., Ltd.).

  The weight average molecular weight calculated | required from GPC-MALLS of the styrene- (meth) acrylic-type copolymer (A) used by this invention becomes like this. Preferably it is 350,000-1 million, More preferably, it is 500,000-900,000. When the weight average molecular weight of the copolymer (A) is in the above range, not only the relaxation of stress when the label is thermally shrunk is suppressed and the bottle shape retention is improved, but also a shrinkage gradient and impact resistance, which will be described later. The compatibility with the block copolymer (B) is good, and further, the fluidity at the time of extrusion and the spreadability at the time of stretching are good and the productivity is also excellent, which is preferable.

  Moreover, from the point which can combine the moldability of the resin composition for heat shrinkable films obtained, and the bottle shape retainability of the heat shrinkable film obtained at a high level, the said styrene- (meth) acrylic-type copolymer ( In the logarithmic graph of A) with the weight average molecular weight determined from GPC-MALLS as the horizontal axis and the inertial radius as the vertical axis, the slope in the region where the molecular weight is 100,000 to 10,000,000 is 0.20 to 0.00. 45 is preferred. In addition, the above-mentioned large inclination means that the characteristics of having a multi-branched structure are less likely to be expressed with physical properties closer to the linear styrene- (meth) acrylic copolymer, A small inclination means an increase in molecular weight accompanying an increase in the degree of branching.

  Moreover, based on JIS K7121 of the said styrene- (meth) acrylic-type copolymer (A), the glass transition obtained by the temperature rising rate of 20 degree-C / min measurement conditions using the differential scanning calorimeter (DSC). As the temperature Tg, there is little dimensional change (natural shrinkage) when processed into a heat-shrinkable film and stored at room temperature, or when a cylindrical label just printed and attached to a bottle is stored at room temperature, and The temperature is preferably 50 to 80 ° C., particularly preferably 60 to 75 ° C. from the viewpoint that the low-temperature shrinkability is sufficient and the PET bottle or the like is not easily deformed when shrink-attached by a shrink tunnel or the like.

  Furthermore, the mass ratio (a1) / () between the multi-branched styrene- (meth) acrylic copolymer (a1) and the linear styrene- (meth) acrylic copolymer (a2) having no multibranched structure. As a2), 70/30 to 30/70 from the point that compatibility with the block copolymer (B) described later is good, uniform stretching is easy, and the bottle shape retention of the resulting film is excellent. It is preferable that it is the range of these.

  In addition, the melt mass flow rate (MFR) of the styrene- (meth) acrylic copolymer (A) is not particularly limited, and may be appropriately adjusted based on the selection of a film processing method. If it is a numerical value measured at a temperature of 200 ° C. and a load of 49 N in accordance with JIS K7210: 99 and within a range of 3 to 12 g / 10 min, the extrudability and stretching of the heat-shrinkable film obtained from the composition of the present invention. This is preferable because it can provide balanced properties with respect to property, shrinkage, transparency, and impact resistance.

  The multibranched styrene- (meth) acrylic copolymer (a1) contained in the styrene- (meth) acrylic copolymer (A) of the present invention has a multibranched structure in one molecule. A multi-branched macromonomer (x1) having a double bond at the molecular end (hereinafter referred to as a multi-branched macromonomer (x1)), a styrene monomer (x2), a (meth) acrylic monomer (x3 ) And a copolymer obtained by polymerizing.

The multi-branched styrene- (meth) acrylic copolymer (a1) is a saturated carbon atom in which all three bonds other than an electron withdrawing group and a bond to be bonded to the electron withdrawing group are bonded to a carbon atom. It preferably has a plurality of one or more types of bond units selected from the group consisting of an ether bond, an ester bond and an amide bond. The electron withdrawing group content is 2.5 × 10 ^{−4 to} 5.0 × 10 ⁻¹ mmol, preferably 5.0 ×, per 1 g of the multi-branched styrene- (meth) acrylic copolymer (a1). 10 ^{−4 to} 5.0 × 10 ⁻² mmol.

As the multibranched macromonomer (x1) used as a raw material of the multibranched styrene- (meth) acrylic copolymer (a1), an electron withdrawing group and a bond other than a bond bonded to the electron withdrawing group in one molecule are used. Mention may be made of hyperbranched macromonomers containing a branched structure consisting of a saturated carbon atom in which all three bonds are bonded to a carbon atom and a double bond bonded directly to the aromatic ring at the end. This hyperbranched macromonomer is a hyperbranched macromonomer derived from AB type ₂ monomer.

Such a branched structure can be easily obtained by a nucleophilic substitution reaction of an active methylene group to which an electron withdrawing group is bonded. Examples of the electron withdrawing group include —CN, —NO ₂ , —CONH ₂ , —CON (R) ₂ , —SO ₂ CH ₃ , —P (═O) (OR) _{2, and the} like. When the methylene group to which the attractive group is bonded is directly bonded to the aromatic ring or the carbonyl group, the activity of the methylene group is further increased.

  Examples of the multibranched macromonomer (x1) used in the present invention include a multibranched macromonomer having a branched chain containing a repeating unit represented by the following general formula.

［式中、Ｙ_１は−ＣＮ、−ＮＯ_２、−ＣＯＮＨ_２、−ＣＯＮ（Ｒ）_２、−ＳＯ_２ＣＨ_３、−Ｐ（＝Ｏ）（ＯＲ）_２（ここでＲはアルキル基またはアリール基を表す）から成る群から選ばれる電子吸引基であり、Ｙ_２はアリーレン基、−Ｏ−ＣＯ−または−ＮＨ−ＣＯ−であり、Ｚは−（ＣＨ_２）_ｎＯ−、−（ＣＨ_２ＣＨ_２Ｏ）_ｎ−、−（ＣＨ_２ＣＨ_２ＣＨ_２Ｏ）_ｎ−から成る群から選ばれる基であり、かつＹ_２が−Ｏ−ＣＯ−または−ＮＨ−ＣＯ−である場合はＺは−（ＣＨ_２）_ｎ−、−（ＣＨ_２）_ｎＡｒ−、−（ＣＨ_２）_ｎＯ−Ａｒ−、−（ＣＨ_２ＣＨ_２Ｏ）_ｎ−Ａｒ−、または−（ＣＨ_２ＣＨ_２ＣＨ_２Ｏ）_ｎ−Ａｒ−（ここでＡｒはアリール基である）を表す］

[Wherein Y ₁ represents —CN, —NO ₂ , —CONH ₂ , —CON (R) ₂ , —SO ₂ CH ₃ , —P (═O) (OR) ₂ (where R represents an alkyl group or aryl Y ₂ is an arylene group, —O—CO— or —NH—CO—, and Z is — (CH ₂ ) _n O—, — (CH ₂ CH ₂ O) _n —, a group selected from the group consisting of — (CH ₂ CH ₂ CH ₂ O) _n —, and when Y ₂ is —O—CO— or —NH—CO—, Z is _{- (CH 2) n -,} - (CH 2) n Ar -, - (CH 2) n O-Ar -, - (CH 2 CH 2 O) n -Ar-, or _- (CH 2 _CH 2 CH ₂ O) _n -Ar- (wherein Ar represents an aryl group)]

As Y ₂ , for example,

等のアリーレン基が挙げられる。これらのなかでもＹ_１が−ＣＮ、Ｙ_２がフェニレン基であることが好適である。Ｙ_２がフェニレン基である場合は、Ｚの結合位置はｏ−位、ｍ−位又はｐ−位のいずれであってもよく特に制限されるものではないが、ｐ−位が好ましい。またＺの繰り返し数ｎは特に制限されるものではないが、スチレン系モノマー（ｘ２）との相溶性が良好である点から１〜１２であることが好ましく、更に好ましくは２〜１０である。

And arylene groups such as Of these, Y ₁ is preferably —CN and Y ₂ is preferably a phenylene group. When Y ₂ is a phenylene group, the bonding position of Z may be any of the o-position, m-position and p-position, and is not particularly limited, but the p-position is preferred. The number n of repeating Z is not particularly limited, but is preferably 1 to 12 and more preferably 2 to 10 in view of good compatibility with the styrene monomer (x2).

The multi-branched macromonomer having a branched structure is in the presence of a basic compound,
(1) Multi-branched self-condensation polycondensate obtained by nucleophilic substitution reaction of AB ₂ type monomer having active methylene group and leaving group in nucleophilic substitution reaction of active methylene group in one molecule (2) Removal of an unreacted active methylene group or methine group remaining in the polycondensate in a nucleophilic substitution reaction of a double bond and an active methylene group directly bonded to an aromatic ring in one molecule. It is obtained by reacting a compound having a leaving group with a nucleophilic substitution reaction.

Here, the leaving group in the nucleophilic substitution reaction of the active methylene group is any halogen bonded to a saturated carbon atom, —OS (═O) ₂ R (R represents an alkyl group or an aryl group), and the like. Specific examples include bromine, chlorine, methylsulfonyloxy group, tosyloxy group and the like. The basic compound is preferably a strong alkali such as sodium hydroxide or potassium hydroxide, and is preferably used as an aqueous solution for the reaction.

Examples of the AB type ₂ monomer having an active methylene group and a leaving group in the nucleophilic substitution reaction of the active methylene group in one molecule include halogenated alkoxy such as bromoethoxy-phenylacetonitrile and chloromethylbenzyloxy-phenylacetonitrile. -Phenylacetonitriles having a tosyloxy group such as phenylacetonitriles, tosyloxy- (ethyleneoxy) -phenylacetonitrile, tosyloxy-di (ethyleneoxy) -phenylacetonitrile, and the like.

  Examples of the compound having a double bond directly bonded to an aromatic ring in one molecule and a leaving group in a nucleophilic substitution reaction of an active methylene group include chloromethylstyrene and bromomethylstyrene.

  In the above (1) showing a multi-branched self-condensation type polycondensate, the reaction for synthesizing a polycondensate as a precursor is clearly shown, and in the above (2), a double bond directly bonded to an aromatic ring is attached to the precursor. A reaction for synthesizing a hyperbranched macromonomer by introducing a bond is described. The reactions (1) and (2) can be performed sequentially, but can also be performed simultaneously in the same reaction system. The molecular weight of the hyperbranched macromonomer can be controlled by changing the compounding ratio of the monomer and the basic compound.

  Preferred examples of the multi-branched macromonomer (x1) used in the present invention include a branched structure composed of one or more repeating structural units selected from an ester bond, an ether bond and an amide bond, and an ethylenic double bond at the branch end. Is a multibranched macromonomer containing

  In the multi-branched macromonomer having an ester bond as a repeating structural unit, the carbon atom adjacent to the carbonyl group of the ester bond forming the molecular chain is a saturated carbon atom, and all the hydrogen atoms on the carbon atom are substituted. An ethylenic double bond such as a vinyl group or an isopropenyl group is introduced into a multi-branched polyester polyol having a molecular chain. When an ethylenic double bond is introduced into a multi-branched polyester polyol, it can be carried out by an esterification reaction or an addition reaction. As the above-mentioned multi-branched polyester polyol, “Boltorn H20, H30, H40” manufactured by Perstorp is commercially available.

  In the above-mentioned multi-branched polyester polyol, a substituent may be introduced into a part of the hydroxyl group by an ether bond or other bond in advance, and a part of the hydroxyl group is modified by an oxidation reaction or other reaction. May be. Further, in the multi-branched polyester polyol, part of the hydroxyl group may be esterified in advance.

  Examples of the multi-branched macromonomer include a compound having one or more hydroxyl groups, a carbon atom adjacent to a carboxyl group is a saturated carbon atom, and all the hydrogen atoms on the carbon atom are substituted, and a hydroxyl group To form a multi-branched polymer by reacting with a monocarboxylic acid having two or more of these, and then reacting the hydroxyl group, which is the terminal group of the polymer, with an unsaturated acid such as acrylic acid or methacrylic acid, an isocyanate group-containing acrylic compound, etc. Can be obtained. The multi-branched polymer having an ester bond as a repeating structural unit is also described in “Angew. Chem. Int. Ed. Engl. 29” p138-177 (1990) by Tamalia et al.

  Examples of the compound having at least one hydroxyl group include a) aliphatic diol, alicyclic diol, or aromatic diol, b) triol, c) tetraol, d) sugar alcohols such as sorbitol and mannitol, e) anne Hydroenenea-heptitol or dipentaerythritol, f) α-alkyl glucoside such as α-methylglycoside, g) monofunctional alcohol such as ethanol, hexanol, h) molecular weight at most 8000, and alkylene oxide or its Examples thereof include a hydroxyl group-containing polymer produced by reacting a derivative with one or more hydroxyl groups of an alcohol selected from any one of the above a) to g).

  Examples of the aliphatic diol, alicyclic diol, and aromatic diol include 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Diol, polytetrahydrofuran, dimethylolpropane, neopentylpropane, 2-propyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 1,3-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol , Dipropylene glycol, tripropylene glycol, polypropylene glycol; cyclohexanedimethanol, 1,3-dioxane-5,5-dimethanol; 1,4-xylylenediethanol, 1-phenyl-1,2-ethanediol, etc. It is done.

  Examples of the triol include trimethylolpropane, trimethylolethane, trimethylolbutane, glycerol, 1,2,5-hexanetriol, and the like.

  Examples of tetraols include pentaerythritol, ditrimethylolpropane, diglycerol, and ditrimethylolethane.

  Examples of the aromatic compound having two or more hydroxyl groups bonded to the aromatic ring include 1,3,5-trihydroxybenzene, 1,4-xylylenediethanol, 1-phenyl-1,2-ethanediol and the like. Can be mentioned.

  Examples of monocarboxylic acids in which the carbon atom adjacent to the carboxyl group is a saturated carbon atom and all the hydrogen atoms on the carbon atom are substituted and have two or more hydroxyl groups include, for example, dimethylolpropionic acid, α, Examples include α-bis (hydroxymethyl) butyric acid, α, α, α-tris (hydroxymethyl) acetic acid, α, α-bis (hydroxymethyl) valeric acid, α, α-bis (hydroxymethyl) propionic acid. By using the monocarboxylic acid, the ester decomposition reaction is suppressed and a multi-branched polyester polyol can be formed.

  Further, it is preferable to use a catalyst when producing the multi-branched polymer, and examples of the catalyst include organic tin compounds such as dialkyltin oxide, dialkyltin halide, dialkyltin biscarboxylate, or stannoxane. And titanates such as tetrabutyl titanate, and organic sulfonic acids such as Lewis acid and paratoluenesulfonic acid.

A hyperbranched macromonomer having an ether bond as a repeating structural unit is converted into a hyperbranched polymer by, for example, reacting a cyclic ether compound having at least one hydroxyl group with a compound having at least one hydroxyl group, Examples thereof include those obtained by reacting a hydroxyl group as a terminal group with an unsaturated acid such as acrylic acid or methacrylic acid, an isocyanate group-containing acrylic compound, or a halogenated methylstyrene such as 4-chloromethylstyrene. In addition, as a method for producing a hyperbranched polymer, a compound having one or more hydroxyl groups, two or more hydroxyl groups and a halogen atom, -OSO ₂ OCH ₃ or -OSO ₂ CH based on Williamson's ether synthesis method A method of reacting with a compound containing ₃ is also useful.

  As the compound having one or more hydroxyl groups, any of those described above can be used. Examples of the cyclic ether compound having one or more hydroxyl groups include 3-ethyl-3- (hydroxymethyl) oxetane, 2,3-epoxy-1-propanol, 2,3-epoxy-1-butanol, 3,4 -Epoxy-1-butanol and the like.

  The compound having one or more hydroxyl groups used in Williamson's ether synthesis method may be those described above, but an aromatic compound having two or more hydroxyl groups bonded to an aromatic ring is preferred. Examples of such a compound include 1,3,5-trihydroxybenzene, 1,4-xylylenediethanol, 1-phenyl-1,2-ethanediol and the like.

Examples of the compound containing two or more hydroxyl groups and a halogen atom, -OSO ₂ OCH ₃ or -OSO ₂ CH ₃ include 5- (bromomethyl) -1,3-dihydroxybenzene and 2-ethyl-2. -(Bromomethyl) -1,3-propanediol, 2-methyl-2- (bromomethyl) -1,3-propanediol, 2- (bromomethyl) -2- (hydroxymethyl) -1,3-propanediol, etc. Can be mentioned.

In the production of the multi-branched polymer, it is preferable to use a normal catalyst. Examples of the catalyst include BF ₃ diethyl ether, FSO ₃ H, ClSO ₃ H, HClO _{4 and the} like. it can.

  In addition, examples of the hyperbranched macromonomer having an amide bond as a repeating structural unit include, for example, those in which amide bonds are repeated in the molecule through nitrogen atoms. (PAMAM dentrimer).

  As the number of double bonds directly bonded to the aromatic ring introduced into the multi-branched macromonomer (x1) increases, the copolymer with the styrene monomer (x2) and the (meth) acrylic monomer (x3) The degree of branching of a certain multibranched styrene- (meth) acrylic copolymer (a1) can be increased.

The degree of branching (DB) of the hyperbranched macromonomer (x1) used in the present invention is defined by the following formula 1, and the range of the degree of branching (DB) is preferably 0.3 to 1.0.
DB = (D + L) / (D + T + L) (1)
(In the formula, D represents the number of dendritic units, L represents the number of linear units, and T represents the number of terminal units)

In addition, said D, L, and T can be calculated | required by the 2nd, 3rd, 4th carbon atom number derived from the active methylene group and its reaction which can be measured by < ¹³ > C-NMR, D is the 4th carbon atom number. In addition, L corresponds to the number of third carbon atoms, and T corresponds to the number of second carbon atoms.

  As the weight average molecular weight of the multibranched macromonomer (x1) used in the present invention, the weight average molecular weight of the multibranched styrene- (meth) acrylic copolymer (a1) can be controlled to 10 million or less. It is preferable that it is 1000-15000, and it is more preferable that it is 2000-5000.

  The content of the double bond directly bonded to the aromatic ring introduced into the multibranched macromonomer (x1) is preferably 0.1 to 5.5 mmol per 1 g of the multibranched macromonomer (x1). It is still more preferable that it is 0.5-3.5 mmol. When the amount is less than 0.1 mmol, it is difficult to obtain a high-molecular-weight multi-branched styrene- (meth) acrylic copolymer, and when it exceeds 5.5 mmol, the multi-branched styrene- (meth) acrylic copolymer is not obtained. The molecular weight tends to increase excessively.

  Examples of the styrene monomer (x2) constituting the styrene- (meth) acrylic copolymer (A) in the present invention include α-methylstyrene, α-methyl-p-methylstyrene, etc. in addition to styrene. Nuclear-substituted styrene such as α-alkyl-substituted styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, m-vinylphenol, p-methoxystyrene, etc. These may be used alone or in combination of two or more. Among these, it is preferable to use styrene because it is inexpensive, has good reactivity, is easy to polymerize, and the shrinkable film has good transparency.

  The (meth) acrylic monomer (x3) constituting the styrene- (meth) acrylic copolymer (A) is an acrylic monomer and / or a methacrylic monomer, and is preferably a (meth) acrylic ester. Particularly preferred are those having an alkyl group having 1 to 20 carbon atoms, and acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, etc. , Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, methacrylic acid Examples include methacrylic esters such as thearyl, and the glass transition temperature of the styrene- (meth) acrylic copolymer (A) becomes a desired value by one or a combination of two or more selected from these monomers. As such, it may be appropriately selected and used.

  Among the (meth) acrylic monomers (x3), the high molecular weight of the styrene- (meth) acrylic copolymer (A) is suppressed, and the low-temperature shrinkability and transparency of the resulting shrinkable film will be described later. Methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate are used from the viewpoint of compatibility with the block copolymer (B), commercial availability, and low cost. Things are more preferable.

  By polymerizing the multibranched macromonomer (x1), the styrene monomer (x2), and the (meth) acrylic monomer (x3), the multibranched styrene- (meth) acrylic copolymer (a1) and The styrene- (meth) acrylic copolymer (A) used in the present invention, which is a mixture with a linear styrene- (meth) acrylic copolymer (a2) that does not have a multi-branched structure that is produced simultaneously. Can be obtained.

  In the copolymerization reaction, the charge mass ratio between the styrene monomer (x2) and the (meth) acrylic monomer (x3) is the low-temperature shrinkage property of the resulting film and the block copolymer (B) described later. From the viewpoint of compatibility, it is preferable that the range is (x2) / (x3) = 90/10 to 35/65, more preferably 85/15 to 78/22.

  More preferably, the charged mass ratio of the styrene monomer (x2), the methacrylic monomer, and the acrylic monomer is 62 to 85% by mass of the styrene monomer (x2), 3 to 16% by mass of the methacrylic monomer, and acrylic. It is a 6-19 mass% type | system | group monomer.

  The blending ratio of the hyperbranched macromonomer (x1) with respect to the total amount of the styrene monomer (x2) and the (meth) acrylic monomer (x3) is the styrene- (meth) acrylic copolymer (A ) Can be efficiently produced, and is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.2% by mass, from the viewpoint of excellent bottle shape retention of the resulting film. Preferably, it is 0.02-0.15 mass%.

  The polymerization reaction of the styrene- (meth) acrylic copolymer (A) used in the present invention is not particularly limited, and has been conventionally used as a polymerization method for styrene- (meth) acrylic copolymers. The method can be used and no special consideration is required by using the hyperbranched macromonomer (x1). The polymerization method is not particularly limited, but bulk polymerization, suspension polymerization, or solution polymerization is preferable. Among them, continuous bulk polymerization is particularly preferable from the viewpoint of production efficiency.For example, by performing continuous bulk polymerization incorporating one or more stirred reactors and a tubular reactor in which a plurality of mixing elements having no moving parts are fixed. A copolymer having excellent molecular weight uniformity can be obtained. Although thermal polymerization can be performed without using a polymerization initiator, it is preferable to use various radical polymerization initiators. In addition, as a polymerization aid such as a suspending agent and an emulsifier necessary for polymerization, various conventional ones used in the production of styrene- (meth) acrylic copolymers can be used.

  Among the continuous bulk polymerization methods, the method of polymerizing using a continuous bulk polymerization line in which a plurality of tubular reactors in which a plurality of mixing elements having no moving parts are fixed is connected, results in good composition uniformity. Particularly preferred. In addition, it is also preferable to perform continuous bulk polymerization by mixing each raw material component and then polymerizing in one or more stirring type reactors and further introducing it into the continuous bulk polymerization line.

  Here, from the viewpoint of productivity, it is used as a continuous polymerization line connected to a continuous bulk polymerization line connecting a plurality of stirred reactors and a tubular reactor in which a plurality of mixing elements having no moving parts are fixed. Preferably, such a continuous polymerization line includes, for example, a. A stirred reactor; b. An initial polymerization line consisting of one or more tubular reactors within which a plurality of mixing elements with no moving parts are connected, followed by a stirred reactor; c. A main polymerization line consisting of one or more tubular reactors in which a plurality of mixing elements with no moving parts are connected, continued from the initial polymerization line; d. It is particularly preferable that the polymerization line is constituted by a reflux line that branches between the initial polymerization line and the main polymerization line and returns to the initial polymerization line.

  Examples of the mixing element used here include an element that mixes the polymerization liquid by changing the division and flow direction of the flow of the polymerization liquid flowing into the pipe and repeating the division and merging. Examples of such tubular reactors include SMX type and SMR type sulzer type tubular mixers, Kenix type static mixers, Toray type tubular mixers, and the like.

  Hereinafter, a method for polymerizing the styrene- (meth) acrylic copolymer (A) using this continuous bulk polymerization line will be described with reference to the process diagram of FIG.

  The raw material components are first sent to the stirring reactor (2) by the plunger pump (1) and subjected to initial graft polymerization under stirring, and then the tubular reactor (4) having a static mixing element by the gear pump (3). ), (5) and (6) and a geared pump (7).

  In the initial polymerization in the stirring reactor (2), the total polymerization conversion of the styrene monomer (x2) and the (meth) acrylic monomer (x3) is 10 to 40 at the outlet of the reactor (2). It is preferable to carry out until the content becomes 10% by mass, preferably 14 to 30% by mass. Examples of the stirring reactor (2) include a stirring tank reactor, a stirring tower reactor, and the like, and examples of the stirring blade include an anchor type, a turbine type, a screw type, a double helical type, Examples include a stirring blade of a log bone type.

  Next, in the circulation polymerization line (I), the polymerization proceeds while the polymerization solution is circulated, and a part of the polymerization solution is sent to the next non-circulation polymerization line (II). Here, the ratio of the flow rate of the polymerization liquid circulating in the circulation polymerization line (I) and the flow rate of the polymerization liquid flowing out to the non-circulation polymerization line (II), the reflux ratio R is The flow rate of the mixed solution refluxed in the circulation polymerization line (I) without flowing out is defined as F1 (liter / hour), and the flow rate F2 of the mixed solution flowing out from the circulation polymerization line (I) into the non-circulation polymerization line (II) ( In general, R = F1 / F2 is preferably in the range of 3 to 15.

  In addition, the polymerization in the circulation polymerization line (I) usually has a total polymerization conversion ratio of the styrene monomer (x2) and the (meth) acrylic monomer (x3) at the outlet of the circulation polymerization line (I). Polymerization is carried out so as to be 30 to 70% by mass, preferably 35 to 65% by mass. A polymerization temperature of 120 to 140 ° C. is suitable.

  The polymerization temperature in the non-circulation polymerization line (II) is usually a polymerization temperature of 140 to 160 ° C., and the graft polymerization is continuously performed until the polymerization conversion rate becomes 60 to 90% by mass.

  Next, this mixed solution is sent to a preheater and then to a devolatilization tank by a gear pump (11), and after removing unreacted monomer and solvent under reduced pressure, the desired copolymer is formed by pelletization. (A) is obtained.

  In addition, a solvent may be used to reduce the viscosity during the polymerization reaction, and the amount used is preferably 5 to 20 parts by mass with respect to a total of 100 parts by mass of monomers used as raw materials. As the type of the solvent, a solvent generally used in the bulk polymerization method of styrene resin can be used, and among them, ethylbenzene, toluene, xylene and the like are suitable.

  In order to adjust the molecular weight of the styrene- (meth) acrylic copolymer (A), a chain transfer agent can be added. The addition amount of the chain transfer agent is usually in the range of 0.005 to 0.5 parts by mass with respect to a total of 100 parts by mass of monomers used as raw materials. The chain transfer agent may be a monofunctional chain transfer agent having one chain transfer group or a polyfunctional chain transfer agent having a plurality of chain transfer agents.

  Examples of the monofunctional chain transfer agent include alkyl mercaptans and thioglycolic acid esters. Examples of the polyfunctional chain transfer agent include polyhydric alcoholic hydroxyl groups such as ethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, thioglycolic acid or 3-mercaptopropion. Those esterified with an acid may be mentioned.

  In order to produce the styrene- (meth) acrylic copolymer (A) used in the present invention, as described above, the hyperbranched macromonomer (x1), the styrene monomer (x2), and the (meth) acrylic monomer ( In addition to the method of polymerizing x3) in a single stage, a multi-branched styrene- (meth) acrylic copolymer (a1) and a linear styrene- (meth) having no multi-branched structure are separately separately provided in advance. The acrylic copolymer (a2) may be mixed to obtain a multi-branched styrene- (meth) acrylic copolymer (A) having an arbitrary mixing ratio.

  Even if the styrene- (meth) acrylic copolymer (A) used in the present invention contains an ultrahigh molecular weight multi-branched styrene- (meth) acrylic copolymer, gelation substantially occurs. Therefore, it can be used because it dissolves easily in an organic solvent.

  The styrene- (meth) acrylic copolymer (A) is preferably polymerized by, for example, the above method, and further, unreacted monomers, oligomers and solvents are removed under reduced pressure, and finally pelletized. .

  The block copolymer (B) used in the present invention is a block copolymer having a styrene polymer block (b1) mainly composed of a styrene monomer and a conjugated diene polymer block (b2) mainly composed of a conjugated diene. It is characterized by being. As the styrenic monomer constituting the styrenic polymer block (b1), any of the various compounds exemplified above as the styrenic monomer (x2) can be mentioned, and it is particularly preferable to use styrene. Examples of the conjugated diene constituting the conjugated diene polymer block (b2) include butadiene, chloroprene, isoprene, 1,3-pentadiene, etc., but butadiene is preferred because of its excellent reactivity with styrene monomers. It is preferable to use it.

  As said block copolymer (B), 30-80 mass% of styrene polymer blocks (b1) from the point which is excellent in compatibility with the above-mentioned styrene- (meth) acrylic-type copolymer (A), It is preferable to contain 70-20 mass% of conjugated diene polymer blocks (b2). In particular, from the viewpoint of good transparency, the main component may be one containing 65 to 85% by mass of the styrene polymer block (b1) and 15 to 35% by mass of the conjugated diene polymer block (b2). preferable.

  Further, the block copolymer (B) may be used alone, but the compatibility with the above-mentioned styrene- (meth) acrylic copolymer (A) is improved, and the resulting film is transparent. Two or more kinds of block copolymers having different composition ratios may be used in combination in order to improve impact properties without impairing the properties. In this case, 65 to 85 masses of the styrene polymer block (b1) is used. %, A conjugated diene polymer block (b2) containing 15 to 35 mass% (B-1), a styrene polymer block (b1) 30 to 65 mass%, and a conjugated diene polymer block (b2). It is preferable to use together the block copolymer (B-2) containing 35-70 mass%.

When the block copolymer (B) is on the higher temperature side than the glass transition temperature derived from the conjugated diene polymer block (b2) and the glass transition temperature is in the range of 90 to 110 ° C., the styrene- (meta ) It is preferable because the compatibility with the acrylic copolymer (A) is good, and the stretched film obtained from the resin composition of the present invention is excellent in the balance between low-temperature shrinkage, transparency and impact strength. Furthermore, using the block copolymer (B-2) having a glass transition temperature of 85 to 105 ° C. further improves the compatibility between the components and further improves the balance of shrinkage gradient and impact properties. To preferred. The ratio of the polymer blocks (b1) and (b2) can be calculated by FT-IR or ¹ H-NMR.

  It does not specifically limit as a manufacturing method of a block copolymer (B), It can manufacture by various methods. For example, it can be produced by the methods disclosed in Japanese Patent Publication Nos. 47-4361 and 48-48546.

  As the resin composition of the present invention, the block film is used with respect to 100 parts by mass of the styrene- (meth) acrylic copolymer (A) because the resulting film has excellent impact strength and good transparency. It is preferable to mix 50 to 300 parts by mass of the polymer (B), particularly 70 to 200 parts by weight. Furthermore, the block copolymer (B-2) may be used in the range of 5 to 40 parts by mass in order to balance the performance as a shrinkable film with respect to 100 parts by mass of the block copolymer (B). .

  The resin composition for heat-shrinkable film of the present invention preferably further contains a rubber-modified styrenic polymer (C) containing a rubbery polymer as dispersed particles. When the rubber-modified styrenic polymer (C) is used in combination, the film surface can be uniformly roughened without impairing the heat shrinkability and transparency of the resulting low-temperature shrinkable film. In addition, the slipperiness can be imparted, and at the same time, the tearability when the shrink film after printing is formed into a cylindrical label can be improved.

  Examples of the rubber-modified styrenic polymer (C) include high impact polystyrene (HIPS) and methacrylic acid-butadiene-styrene copolymer (MBS). These may be used in combination. In particular, it is preferable to use HIPS as a main component because the stretched film obtained from the resin composition of the present invention is excellent in anti-blocking property and balance between slipperiness and transparency.

  The average particle size of the rubber-like polymer contained in the rubber-modified styrenic polymer (C) is preferably less than 2 μm from the viewpoint of good transparency of the resulting film. When the average particle size is 2 μm or more, the anti-blocking property and the slip property of the stretched film obtained from the resin composition are improved, but the transparency may be lowered. The dispersion particle size can be measured by various methods, for example, a technique described in JP-A-4-351562, page 8, and transmission electron micrographs taken by an ultrathin film section method are taken. It can be determined by measuring the dispersed particle size.

  As the blending amount of the rubber-modified styrene polymer (C), the styrene- (meth) acrylic copolymer ( A) It is preferable that it is 1-10 mass parts with respect to 100 mass parts, More preferably, it is the range of 1.5-5 mass parts.

  In addition, since the balance of transparency, anti-blocking property and slipperiness of the film is good, a rubber-modified styrene polymer (C) having an average particle size of the rubber-like polymer of 0.5 to 2 μm and a lubricant are used in combination. It is preferable. The lubricant preferably has a melting point of 100 ° C. or higher in order to avoid a decrease in transparency due to bleed-out of the lubricant during heat shrinkage. For example, higher fatty acid, higher fatty acid ester, higher fatty acid metal edge, higher fatty acid amide, etc. However, higher fatty acid amides are more preferable from the viewpoint of excellent anti-blocking properties and a balance between slipperiness and transparency. Specifically, ethylene-bis-stearic acid amide, hexamethylene-bis-stearic acid amide, And hexamethylene-bis-behenic acid amide.

  Although it does not specifically limit as a preparation method of the resin composition for heat-shrinkable films of this invention, From the point which is excellent in the uniformity of the composition obtained by performing melt blending. Specific examples include a method of mixing each component by heating and melting, for example, styrene- (meth) acrylic copolymer (A), block copolymer (B), and optionally used in combination. The rubber-modified styrenic polymer (C) pellets or pearls are melt blended at 190-240 ° C. in an extruder and formed into a film as it is, and the pellets are once pelletized and then melt-kneaded again in an extruder. Or a master batch in which the styrene- (meth) acrylic copolymer (A) and additives are melt blended at one end, and the block copolymer (B) is dry blended to form a film. Can be mentioned. Moreover, as a mixing method, it can manufacture by various various mixing methods. For example, the target composition can be obtained by melt-kneading with a single screw extruder, a twin screw extruder, a kneader, an open roll or the like. The temperature at the time of melt mixing in the above method is preferably 240 ° C. or lower in order to prevent gelation of the conjugated diene polymer block (b2) and the like in the block copolymer (B).

  In addition, the resin composition of the present invention inhibits the low-temperature shrinkability, shrinkage gradient, and bottle shape retention of the resulting low-temperature shrinkable film for the purpose of preventing gelation of the conjugated diene polymer block (b2) and the like. An appropriate amount of antioxidant can be added within the range not to be used. As the antioxidant, a primary antioxidant such as a phenol compound and a secondary antioxidant such as a phosphorus compound can be used alone or in combination. In addition, various additives that can be generally added to a styrene resin, such as an ultraviolet absorber, a colorant, a heat stabilizer, a plasticizer, and a dye, may be mixed. These additives can be added during the kneading of the resin composition or during the polymerization of each polymer. Specific examples include mineral oils, plasticizers such as ester plasticizers, polyester plasticizers, silicone oils, and the like, and one or more of these can be added and used.

  The resin composition of the present invention has both the above-mentioned various conditions, and as a shrinkable film, it has low shrinkage, an appropriate shrinkage gradient, and excellent bottle shape retainability that could not be realized so far. Can do.

  The heat-shrinkable film of the present invention is obtained by using the resin composition of the present invention. However, the production method is not particularly limited, and can be obtained by various methods. For example, after making the resin composition of the present invention into a molten state using an extruder or the like, it is extruded into a film shape through a T-die, the film is once cooled with a chill roll or an air knife, and then 1 using a stretching apparatus. The method of extending | stretching to an axis | shaft or a biaxial simultaneously or sequentially is mentioned.

  When the resin composition of the present invention is extruded into a film through a T-die, the resin temperature in the extruder is preferably 190 to 240 ° C, and more preferably 200 to 230 ° C. This is more preferable because the effect of preventing gelation and the like and the fine dispersion effect of the rubber-modified styrene copolymer (C) and the like are enhanced.

  The low-temperature shrinkable film of the present invention may be a multilayered stretched film using two or more kinds of the resin composition of the present invention. In addition, the resin composition of the present invention is used as a main layer, and two or more layers, two or three layers, or three or three layers are formed on one or both surface layers using a styrenic resin composition outside the scope of the present invention. A stretched film may be used. However, in this case, in order to express the low-temperature shrinkage, the proper shrinkage gradient, and the bottle shape retainability that are the characteristics of the present invention, the layer mainly composed of the composition of the present invention is preferably 60% by mass or more.

  As the stretching method, a roll stretching method, a tenter method, and an inflation method can be used, but the tenter method is preferable because the uniformity of the stretching orientation is improved in the main stretching direction. The draw ratio may be adjusted as appropriate depending on the required shrinkage rate, but from the viewpoint of the appropriate shrinkage gradient of the stretched film obtained from the resin composition of the present invention and productivity, the stretch ratio is 2-6. Times, preferably 3 to 4 times. The stretching temperature may be appropriately adjusted depending on the residence time in the stretching step, but (glass transition temperature of the resin composition) to (glass transition temperature of the resin composition + 30 ° C.), preferably (the glass transition temperature of the resin composition). + 5 ° C) to (glass transition temperature of the resin composition + 20 ° C).

  Further, a stretching process may be performed in the main stretching direction and the vertical direction. Examples of the stretching method include a roll stretching method using a speed difference between heated rolls and a simultaneous biaxial stretching method in a tenter. The magnification may be adjusted as appropriate according to the required shrinkage rate, but it suppresses the expansion in the vertical direction accompanying the shrinkage in the main stretching direction and improves the finish after shrinkage of the shrink label. Double is preferable, More preferably, it is 1.05-1.2 times.

  The heat-shrinkable film of the present invention has a heat shrinkage rate of 5% or more when immersed in hot water at 70 ° C. for 10 seconds, and the main stretching direction when immersed in hot water at 80 ° C. for 10 seconds. The heat shrinkage ratio is 30% or more and less than 60%.

  Shrink labels for beverage bottles such as PET bottles are made into a cylindrical shape so that the relaxation rate is 5 to 10% of the maximum circumference of the bottle, and after being attached to the bottle, it is shrunk in a shrink tunnel, etc. Label. Therefore, the temperature at which 5% shrinkage is important. In particular, in the case of the above-described shrink film for an aseptic filling method, the PET bottle is a non-heat-resistant thin and light weight bottle, so the 5% shrinkage temperature needs to be 70 ° C. or less. . In addition, the full label that attaches the bottle shape and label to the part where the bottle diameter becomes narrower requires a heat shrinkage rate of 50% or more, so the 80 ° C heat shrinkage rate of the shrink label is less than 30%. In some cases, label waviness occurs due to insufficient shrinkage, and when it exceeds 60%, the shrinkage gradient is too high, so that the proper shrinkage temperature range is narrowed, and the shrink label may be wrinkled.

  The bottle of the present invention is a bottle around which the above-mentioned heat-shrinkable film is wound. Specifically, the bottle is formed by winding the aforementioned shrink label, and the resin composition for heat-shrinkable film according to the present invention is used. It is preferable that the thickness of the bottle is a PET bottle with a thickness of 0.1 to 0.3 mm.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these examples.

The evaluation method of an Example and a comparative example is shown below.
(Continuous block polymerization equipment)
The resin composition obtained in the present example is obtained by an apparatus arranged as shown in FIG. A mixed solution containing various monomers and a solvent was sent to a 20 liter stirred reactor (2) by a plunger pump (1) and subjected to initial polymerization under dynamic mixing with a stirring blade. Subsequently, this mixed solution is sent to the circulation polymerization line (I) by the gear pump (3). The circulation polymerization line (I) has a 2.5 inch inner diameter reactor in order from the inlet (with built-in 30 SMX type static mixers and static mixing elements manufactured by Gebrüter Sulzer, Switzerland), (4), (5) and ( 6) and a gear pump (7) for circulating the mixed solution. Between the tubular reactor (6) and the gear pump (7), the tubular reactors (8), (9) and (10) and the gear pump (11) are the same as described above in order from the inlet to the non-circulation polymerization line (II). Are directly connected.

(Glass transition temperature measurement)
A differential scanning calorimeter (DSC7 manufactured by Perkin Elmer Co.) was used, and measurement was performed at a heating rate of 20 ° C./min in accordance with JIS K7121.

(GPC-MALLS measurement conditions)
GPC-MALLS measurement of styrene- (meth) acrylic copolymer (A) was performed using Shodex HPLC, detector Wyatt Technology DAWN EOS, Shodex RI-101, column Shodex KF-806L × 2, solvent THF, flow rate 1.0 ml. / Min. The analysis of GPC-MALLS measurement is performed by analysis software ASTRA manufactured by Wyatt. Molecular weight, weight average molecular weight, multi-branched styrene- (meth) acrylic copolymer (a1) and linear styrene- (meth) The ratio with the acrylic copolymer (a2) was determined.

  As an example, a chromatograph of a styrene- (meth) acrylic copolymer (A-2) obtained by a synthesis example described later is shown in FIG. The horizontal axis is the amount of solvent flowed from the start of measurement (retention time), the vertical axis is the peak intensity, and the component peak with a smaller amount of solvent has a higher molecular weight. The solid line in the figure is the peak obtained from the measurement results. The ratio of the high molecular weight part (multi-branched styrene- (meth) acrylic copolymer part) (P2) and the low molecular weight part (linear styrene- (meth) acrylic copolymer part) (P1) is high. Using the vertical axis drawn from the top peak of the molecular weight portion, the line symmetry of the high molecular weight portion and the sum of the areas of the high molecular weight portions and the area ratio of the remaining portions obtained by subtracting those portions from the whole were obtained.

  Moreover, the weight calculated | required from GPC-MALLS of the styrene- (meth) acrylic copolymer (A-2) and the styrene- (meth) acrylic copolymer (A′-1) obtained in the synthesis examples described later. A log-log graph of average molecular weight (Molar Mass) -radius of inertia (RMS Radius) is shown in FIG.

(RI-GPC measurement conditions for hyperbranched macromonomer)
GPC measurement of a hyperbranched macromonomer is performed by high performance liquid chromatography (HLC-8220GPC manufactured by Tosoh Corporation), RI detector, TSK gel G6000H × 1 + G5000H × 1 + G4000H × 1 + G3000H × 1 + TSK guard column H × 1, solvent THF, flow rate 1 The test was carried out under the conditions of 0.0 ml / min and a temperature of 40 ° C.

(NMR measurement method)
The amount of ethylenic double bonds of the hyperbranched macromonomer was determined by nuclear magnetic resonance spectroscopy ( ¹ H-NMR), and was shown as the number of moles per sample mass. Moreover, the branching degree of the multibranched macromonomer was calculated | required by calculating | requiring the number of the 2nd, 3rd, 4th carbon atom originating in an active methylene group and its reaction by ¹³ C-NMR.

(Haze measurement)
Based on JIS K7105, the haze value which shows the transparency of the stretched film obtained by the Example and the comparative example was measured using the turbidity / cloudiness meter (made by Nippon Denshoku Industries Co., Ltd.).

(Measurement of heat shrinkage)
The stretched films obtained by Examples and Comparative Examples were cut into 100 mm squares, immersed in a constant temperature water bath adjusted to 70 ° C. and 80 ° C. for 10 seconds, and the shrinkage rate at each temperature was measured from Equation 2 described below. Moreover, the shrinkage gradient was calculated from the shrinkage curve in which the temperature of the thermostatic water bath is taken on the horizontal axis and the shrinkage rate of the film is taken on the vertical axis, and the temperature at which the film shrinks by 5% and Equation 3 described below.
Thermal shrinkage rate = (100−size after shrinkage in the main stretching direction) / 100 × 100 (2)
Thermal shrinkage gradient = (shrinkage ratio in the main stretching direction at 80 ° C.−shrinkage ratio in the main stretching direction at 70 ° C.) / (80 ° C.−70 ° C.) (3)

(Bottle shape retention evaluation method)
A thin and light bottle is shrink-fitted, and with an evaluation device as shown in FIG. 4, a 10 × 300 mm surface of an iron prism with a width of 10 × length of 300 × height of 10 mm is in contact with the side of the bottle. The load corresponding to the maximum quantity of bottles filled in the serpentine column in the vending machine is applied to measure the amount of deformation of the bottle with the shrink label attached, and the deformation rate of the bottle (deformation rate = deformation amount / maximum bottle) (Body diameter × 100) was calculated.

  The bottle used was a non-heat-resistant thin-walled lightweight PET bottle (commercially available) filled with oolong tea having a maximum body diameter of 66 mm, a maximum circumferential length of 208 mm, a weight of 20.5 g / tube, and an internal volume of 500 ml. Moreover, the average wall thickness of the bottle body circumference portion to which the label is attached is 0.23 mm (maximum wall thickness 0.27 mm, minimum wall thickness 0.19). The label is formed into a cylindrical shape having a relaxation rate of 5% (label circumferential length 218 mm) with respect to the maximum body diameter of the bottle so that the main stretching direction is the circumferential direction, and methyl ethyl ketone / ethyl acetate / cyclohexane (volume ratio: 4/3/3). ) And mixed with a mixed solvent and cut to a length of 97 mm in the main stretching direction and the vertical direction. The cylindrical label was attached to the bottle filled with the contents, and contracted with a steam type shrink tunnel (Kyowa Denki Steam Shrinker JK-1000). The shrinkage conditions of the steam type shrink tunnel were an internal temperature of 83 to 88 ° C., and the residence time of the bottle with the label in the tunnel was 8 seconds.

(Melt mass flow rate measurement method)
The measurement was performed according to JIS K7210. The measurement conditions are a temperature of 200 ° C. and a load of 49N.

Synthesis Example 1 [Production Example of Hyperbranched Macromonomer (x1-1)]
In a reaction vessel equipped with a 7 mol% oxygen introduction tube, a thermometer, a Dean-Stark decanter equipped with a condenser, and a stirrer, 10 g of “Borton H20”, 1.25 g of dibutyltin oxide, and methyl methacrylate having an isopropenyl group as a functional group 100 g and 0.05 g of hydroquinone were added, and the mixture was heated with stirring while blowing 7 mol% oxygen at a rate of 3 ml / min. The amount of heating is adjusted so that the amount of distillate in the decanter is 15 to 20 g per hour, the distillate in the decanter is taken out every hour, and the corresponding amount of methyl methacrylate is added for 4 hours. Reacted.

  After completion of the reaction, methyl methacrylate was distilled off under reduced pressure, and 10 g of acetic anhydride and 2 g of sulfamic acid were added to cap the remaining hydroxyl groups, followed by stirring at room temperature for 10 hours. After removing sulfamic acid by filtration and distilling off acetic anhydride and acetic acid under reduced pressure, the residue was dissolved in 70 g of ethyl acetate and washed 4 times with 20 g of 5% by weight aqueous sodium hydroxide solution to remove hydroquinone. . Further, it was washed twice with 20 g of a 7% by mass sulfuric acid aqueous solution and twice with 20 g of water. To the obtained organic layer, 0.0045 g of methoquinone was added, the solvent was distilled off under introduction of 7 mol% oxygen under reduced pressure, and 11 g of a hyperbranched macromonomer (x1-1) having an isopropenyl group and an acetyl group was added. Obtained. The resulting multibranched macromonomer (x1-1) has a weight average molecular weight of 3000 and a number average molecular weight of 2100, and the introduction rate of isopropenyl group and acetyl group into the multibranched macromonomer (x1-1) is: They were 55 mol% and 36 mol%, respectively. The resulting multibranched macromonomer has a degree of branching of 1.0 and contains a double bond of 2.4 mmol / 1 g monomer at the branch end.

Synthesis Example 2 [Production Example of Styrene- (Meth) acrylic Copolymer (A-1)]
Styrene (St) 79 parts by mass, butyl acrylate (BuA) 19 parts by mass, methyl methacrylate (MMA) 2 parts by mass, multi-branched macromonomer (x1-1) 0.03 parts by mass (monomer ratio 300 ppm), toluene A mixed solution consisting of 10 parts by mass was prepared, and 0.003 parts by mass (30 ppm) of 2,2-bis (4,4-diperoxycyclohexyl) propane was added as a polymerization initiator to 100 parts by mass of the monomer mixture. In addition, [Styrene- (meth) acrylic copolymer (A-1) was obtained by continuous bulk polymerization under the following conditions using the polymerization line shown in the process diagram of FIG.
Reaction temperature in the stirring reactor (2): 115 ° C.
Reaction temperature in circulation polymerization line (I): 120 ° C
Reaction temperature in non-circulation polymerization line (II): 140 to 150 ° C.
The mixed solution obtained by polymerization was heated to 240 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A-1).

Synthesis Example 3 [Production Example of Styrene- (Meth) acrylic Copolymer (A-2)]
In Synthesis Example 2, 0.06 parts by mass (monomer ratio 600 ppm) of the hyperbranched macromonomer (x1-1), and 0.002 parts by mass (20 ppm) of 2,2 parts per 100 parts by mass of the monomer mixture as a polymerization initiator. A styrene- (meth) acrylic copolymer (A-2) was obtained in the same manner as in Synthesis Example 2, except that 2-bis (4,4-di-peroxycyclohexyl) propane was used. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A-2).

Synthesis Example 4 [Production Example of Styrene- (Meth) acrylic Copolymer (A-3)]
Prepare a mixed solution consisting of St 79 parts by mass, BuA 19 parts by mass, MMA 2 parts by mass, multi-branched macromonomer (x1-1) 0.03 parts by mass (monomer ratio 300 ppm), toluene 10.5 parts by mass, As a polymerization initiator, 0.004 parts by mass (monomer ratio 40 ppm) of 2,2-bis (4,4-di-peroxycyclohexyl) propane and 0.005 parts by mass (monomer ratio 50 ppm) with respect to 100 parts by mass of the monomer mixture. N-octyl 3-mercaptopropionate was added, and the same apparatus as in Synthesis Example 2 was used to obtain a styrene- (meth) acrylic copolymer (A-3) by continuous bulk polymerization.
Reaction temperature in the stirring reactor (2): 115 ° C.
Reaction temperature in circulating polymerization line (I): 125 ° C
Reaction temperature in non-circulation polymerization line (II): 140 to 150 ° C.
The mixed solution obtained by polymerization was heated to 240 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A-3).

Synthesis Example 5 [Production Example of Styrene- (Meth) acrylic Copolymer (A-4)]
In Synthesis Example 2, 0.06 parts by mass (monomer ratio 600 ppm) of the hyperbranched macromonomer (x1-1), 0.002 parts by mass (monomer per 100 parts by mass of the monomer mixture as a polymerization initiator and a polymerization regulator) Except that it is changed to using 2,2-bis (4,4-di-peroxycyclohexyl) propane having a ratio of 20 ppm) and 0.005 parts by mass (50 ppm monomer ratio) of n-octyl 3-mercaptopropionate. In the same manner as in Synthesis Example 2, a styrene- (meth) acrylic copolymer (A-4) was obtained. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A-4).

Synthesis Example 6 [Production Example of Styrene- (Meth) acrylic Copolymer (A-5)]
A mixed solution consisting of 82 parts by mass of St, 12 parts by mass of BuA, 6 parts by mass of MMA, 0.03 parts by mass of a multi-branched macromonomer (x1-1) (monomer ratio 300 ppm), and 6 parts by mass of toluene was prepared, and a polymerization initiator was prepared. As a starting material, 0.025 parts by mass (monomer ratio 250 ppm) of t-butylperoxyisopropyl carbonate is added to 100 parts by mass of the monomer mixture, and styrene- (meth) acrylic is obtained by continuous bulk polymerization using the same apparatus as in Synthesis Example 2. A copolymer (A-5) was obtained.
Reaction temperature in stirred reactor (2): 119 ° C
Reaction temperature in circulating polymerization line (I): 123 ° C
Reaction temperature in non-circulation polymerization line (II): 150 to 165 ° C
The mixed solution obtained by polymerization was heated to 240 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A-5).

Synthesis Example 7 [Production Example of Styrene- (Meth) acrylic Copolymer (A′-1)]
A mixed solution consisting of 79 parts by weight of St, 19 parts by weight of BuA, 2 parts by weight of MMA, and 8 parts by weight of toluene was prepared. 2,2-bis (4,4-di-peroxycyclohexyl) propane was added, and the same apparatus as in Synthesis Example 2 was used, and a styrene- (meth) acrylic copolymer having no branched structure by continuous bulk polymerization ( A′-1) was obtained.
Reaction temperature in the stirring reactor (2): 115 ° C.
Reaction temperature in circulation polymerization line (I): 120 ° C
Reaction temperature in non-circulation polymerization line (II): 130 to 150 ° C
The mixed solution obtained by polymerization was heated to 240 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A′-1).

Synthesis Example 8 [Production Example of Styrene- (Meth) acrylic Copolymer (A′-2)]
A mixed solution consisting of 82 parts by mass of St, 12 parts by mass of BuA, 6 parts by mass of MMA, and 9 parts by mass of toluene was prepared. As a polymerization initiator, 0.025 parts by mass (monomer ratio: 250 ppm) of 2 parts per 100 parts by mass of the monomer mixture was prepared. , 2-bis (4,4-di-peroxycyclohexyl) propane, and using the same apparatus as in Synthesis Example 2, a styrene- (meth) acrylic copolymer (A) having no branched structure by continuous bulk polymerization (A '-2) was obtained.
Reaction temperature in the stirring reactor (2): 115 ° C.
Reaction temperature in circulation polymerization line (I): 131 ° C.
Reaction temperature in non-circulation polymerization line (II): 140 to 160 ° C.
The mixed solution obtained by polymerization was heated to 240 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. Table 1 shows the physical properties of the obtained styrene- (meth) acrylic copolymer (A′-2).

[Block copolymers (B-1-1), (B-1-2), (B-2-1)]
As the block copolymer (B-1-1), “K Resin DK11” manufactured by Chevron Phillips Chemical (content of styrene polymer block: 73 mass%, content of butadiene polymer block: 27 mass%, As the block copolymer (B-1-2), a glass transition temperature: 102 ° C., “K Resin XK44” manufactured by Chevron Phillips Chemical (content of styrene polymer block: 75% by mass, butadiene polymer) Block content: 25% by mass, glass transition temperature: 96 ° C.). Further, as a block copolymer (B-2-1), “TR2000” manufactured by JSR (styrene polymer block content: 40 mass%, butadiene polymer block content: 60 mass%, glass transition temperature: 99 ° C) was used.

Synthesis Example 9 [Production Example of Rubber-Modified Styrene Copolymer (C-1)]
A mixed solution consisting of 100 parts by mass of St, 7 parts of polybutadiene (720A manufactured by Asahi Kasei) and 7 parts by mass of ethylbenzene was prepared, and 0.01 parts by mass of t-butylperoxybenzoate was added as a polymerization initiator to 100 parts by mass of the monomer mixture. Using the same apparatus as in Synthesis Example 2, a rubber-modified styrene copolymer (C-1) was obtained by continuous bulk polymerization.
Reaction temperature in the stirring reactor (2): 134 ° C.
Reaction temperature in circulating polymerization line (I): 136 ° C
Reaction temperature in non-circulation polymerization line (II): 150 ° C.
The mixed solution obtained by polymerization was heated to 250 ° C. with a heat exchanger to remove volatile components under reduced pressure, and then pelletized. The average rubber particle size was 0.9 μm, and the polybutadiene rubber content was 7.6% by mass.

Other additives “Irganox B900FF” manufactured by Ciba Specialty Chemicals and “Sumilyzer GS (F)” manufactured by Sumitomo Chemical were used as antioxidants.

Example 1
Styrene- (meth) acrylic copolymer (A-1): 34 parts by mass, styrene- (meth) acrylic copolymer (A-5): 4 parts by mass, block copolymer (B-1-1) ): 53 parts by mass, block copolymer (B-2-1): 9 parts by mass with respect to a total of 100 parts by mass, Irganox B-900FF: 0.1 parts by mass, Sumilyzer GS (F): 0. Using a 30 mmφ twin screw extruder (L / D = 31.5) manufactured by Nippon Steel Works, the resin composition to which 4 parts by mass were added was cylinder temperature 230 ° C., Q / N (discharge amount per rotation) = 0. Kneaded and dispersed at 1 to 0.08, extruded from a die with a lip opening of 0.9 mm and a temperature of 210 ° C., cooled once with a 65 ° C. cooling roll, and then 1. 15 times, draw film by tenter method Ri stretched 3.85 times in the direction vertically to obtain a stretched film (1) of 0.055mm with. Table 2 shows the resin compositions, film processing conditions, and evaluation results of the examples.

Example 2
A stretched film (2) as in Example 1 except that a styrene- (meth) acrylic copolymer (A-2) is used instead of the styrene- (meth) acrylic copolymer (A-1). ) Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 3
A stretched film (3) in the same manner as in Example 1 except that a styrene- (meth) acrylic copolymer (A-3) is used instead of the styrene- (meth) acrylic copolymer (A-1). ) Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 4
Instead of the styrene- (meth) acrylic copolymer (A-1), a styrene- (meth) acrylic copolymer (A-4) is used, and further a rubber-modified styrene copolymer (C-1). ) Was blended in the same manner as in Example 1 except that 1.5 parts by mass was blended to obtain a stretched film (4). Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 5
Styrene- (meth) acrylic copolymer (A-1): 34 parts by mass, styrene- (meth) acrylic copolymer (A-5): 7 parts by mass, block copolymer (B-1-2) ): 50 parts by mass, block copolymer (B-2-1): 9 parts by mass with respect to a total of 100 parts by mass, Irganox B-900FF: 0.1 parts by mass, Sumilyzer GS (F): 0. A stretched film (5) was obtained in the same manner as in Example 1 except that 4 parts by mass of the resin composition was added and the stretch ratio by the roll stretching method was changed to 1.10 times. Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 6
A stretched film (as in Example 5) except that a styrene- (meth) acrylic copolymer (A-2) is used instead of the styrene- (meth) acrylic copolymer (A-1). 6) was obtained. Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 7
A stretched film (as in Example 5) except that a styrene- (meth) acrylic copolymer (A-3) is used instead of the styrene- (meth) acrylic copolymer (A-1). 7) was obtained. Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 8
Instead of the styrene- (meth) acrylic copolymer (A-1), a styrene- (meth) acrylic copolymer (A-4) is used, and further a rubber-modified styrene copolymer (C-1). ) Was blended in the same manner as in Example 5 except that 1.5 parts by mass was blended to obtain a stretched film (8). Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 9
Styrene- (meth) acrylic copolymer (A-2): 40 parts by mass, block copolymer (B-1-1): 53 parts by mass, block copolymer (B-2-1): 7 parts by mass A stretched film (as in Example 1 except that 1.5 parts by mass of the rubber-modified styrene copolymer (C-1) is blended with 100 parts by weight of the resin composition and the stretching temperature is changed. 9) was obtained. Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 10
Styrene- (meth) acrylic copolymer (A-4): 34 parts by mass, styrene- (meth) acrylic copolymer (A′-2): 6 parts by mass, block copolymer (B-1- 1): 53 parts by mass, block copolymer (B-2-1): A stretched film (10) was obtained in the same manner as in Example 1 except that the resin composition was 100 parts by mass. . Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 11
Styrene- (meth) acrylic copolymer (A-4): 39 parts by mass, styrene- (meth) acrylic copolymer (A-5): 4 parts by mass, block copolymer (B-1-2) ): A stretched film (11) was obtained in the same manner as in Example 1 except that the resin composition was 57 parts by weight in total of 100 parts by weight and the stretch ratio in the tenter method was 3.90 times. . Table 2 shows the resin composition, film processing conditions, and evaluation results.

Example 12
Styrene- (meth) acrylic copolymer (A-4): 47 parts by mass, block copolymer (B-1-2): 53 parts by mass A total of 100 parts by mass of the resin composition and tenter A stretched film (12) was obtained in the same manner as in Example 1 except that the stretching ratio in the method was 3.90 times. Table 2 shows the resin composition, film processing conditions, and evaluation results.

  As shown in Table 2, the stretched films (1) to (12) obtained in Examples 1 to 12 all have an appropriate shrinkage gradient and low-temperature shrinkage, have good transparency, and retain bottle shape. It turns out that it is also excellent.

Comparative Example 1
For the resin composition of Example 1, styrene- (meth) acrylic copolymer (A′-1): 34 parts by mass, styrene- (meth) acrylic copolymer (A′-2): 4 parts by mass. Block copolymer (B-1-1): 53 parts by mass, block copolymer (B-2-1): 9 parts by mass In the same manner as in Example 1, except that the total amount is 100 parts by mass. A comparative stretched film (1 ′) was obtained. Table 3 shows the resin composition, film processing conditions, and evaluation results.

Comparative Example 2
For the resin composition of Example 8, styrene- (meth) acrylic copolymer (A′-1): 34 parts by mass, styrene- (meth) acrylic copolymer (A′-2): 7 parts by mass. , Block copolymer (B-2-2): 50 parts by mass, block copolymer (B-2-2): 9 parts by mass In the same manner as in Example 8, except that the total amount is 100 parts by mass. A comparative stretched film (2 ′) was obtained. Table 3 shows the resin composition, film processing conditions, and evaluation results.

Comparative Example 3
Styrene- (meth) acrylic copolymer (A′-1): 38 parts by mass, block copolymer (B-1-2): 53 parts by mass, block copolymer (B-2-1): 9 A comparative stretched film (3 ′) was obtained in the same manner as in Example 1 except that 100 parts by weight of the resin composition in total was used. Table 3 shows the resin composition, film processing conditions, and evaluation results.

Comparative Example 4
Styrene- (meth) acrylic copolymer (A′-2): 47 parts by mass, block copolymer (B-1-1): 53 parts by mass Except using a total of 100 parts by mass of the resin composition, In the same manner as in Example 1, a comparative stretched film (4 ′) was obtained. Table 3 shows the resin composition, film processing conditions, and evaluation results.

  As the results shown in Table 4, the comparative stretched films (1 ′) to (4 ′) are inferior in transparency and bottle shape retention compared to the films (1) to (12) obtained in the examples, and compared. In the stretched film (4 ′) for use, the low-temperature shrinkage was also insufficient.

FIG. 3 is a process diagram illustrating an example of a continuous bulk polymerization line incorporating a tubular reactor having a static mixing element. It is a mass molecular weight distribution calculated | required by GPC-MALLS of a styrene- (meth) acrylic-type copolymer (A-2). Molecular mass (g / mol) -radius of inertia determined by GPC-MALLS for styrene- (meth) acrylic copolymer (A-2) and styrene- (meth) acrylic copolymer (A′-1) It is a log-log graph of (RMS Radius / nm). It is an apparatus for measuring bottle shape retention.

Explanation of symbols

(1): Pusher pump (2): Stirred reactor (3): Gear pump (4): Tubular reactor with static mixing element (5): Tubular reactor with static mixing element (6): Static Tubular reactor (7) with static mixing element: Gear pump (8): Tubular reactor with static mixing element (9): Tubular reactor with static mixing element (10): Tubular with static mixing element Reactor (11): Gear pump (I): Circulation polymerization line (II): Non-circulation polymerization line

Claims (16)

A resin composition comprising a styrene- (meth) acrylic copolymer (A) and a block copolymer (B) having a styrene polymer block (b1) and a conjugated diene polymer block (b2). The styrene- (meth) acrylic copolymer (A) contains a multi-branched styrene- (meth) acrylic copolymer (a1), and the resin composition for heat-shrinkable film is characterized in that . The styrene- (meth) acrylic copolymer (A) is
(1) The weight average molecular weight calculated | required by GPC-MALLS is 350,000-1 million,
(2) In a log-log graph with the weight average molecular weight determined by GPC-MALLS as the horizontal axis and the inertial radius as the vertical axis, the slope in the region of molecular weight of 100,000 to 10 million is 0.20 to 0.45. Item 2. The heat-shrinkable film resin composition according to Item 1. The resin composition for heat-shrinkable film according to claim 1, wherein the styrene- (meth) acrylic copolymer (A) has a glass transition temperature Tg measured in accordance with JIS K 7121 of 50 to 80 ° C. The multi-branched styrene- (meth) acrylic copolymer (a1) and the linear styrene- (meth) acrylic copolymer (a2) constituting the styrene- (meth) acrylic copolymer (A) The resin composition for a heat-shrinkable film according to claim 2, wherein the mass ratio (a1) / (a2) is 30/70 to 70/30. The multi-branched styrene- (meth) acrylic copolymer (a1) comprises a multi-branched macromonomer (x1) having a double bond at the molecular end, a styrene monomer (x2), and a (meth) acrylic copolymer. The resin composition for heat-shrinkable film according to claim 1, which is a copolymer obtained by polymerizing the monomer (x3). The resin composition for a heat-shrinkable film according to claim 5, wherein the hyperbranched macromonomer (x1) is a hyperbranched macromonomer having at least one bond selected from the group consisting of an ester bond, an ether bond and an amide bond. object. The heat shrinkage according to claim 5, wherein the degree of branching of the multi-branched macromonomer (x1) is 0.3 to 1.0, and a double bond is contained at a branching end in an amount of 0.1 to 5.5 mmol per 1 g of the monomer. Resin composition for conductive film. 2. The heat-shrinkable film according to claim 1, wherein 62 to 85 parts by mass of the styrene monomer (x2) is contained in 100 parts by mass of the monomer mixture used as a raw material of the styrene- (meth) acrylic copolymer (A). Resin composition. The resin for heat-shrinkable film according to claim 1, wherein 50 to 300 parts by mass of the block copolymer (B) is blended with 100 parts by mass of the styrene- (meth) acrylic copolymer (A). Composition. The heat-shrinkable film resin composition according to any one of claims 1 to 9, comprising a rubber-modified styrene copolymer (C) containing a rubbery polymer as dispersed particles. The resin composition for heat-shrinkable film according to claim 10, wherein an average particle diameter of dispersed particles in the rubber-modified styrene copolymer (C) is less than 2 μm. The heat-shrinkability of Claim 10 formed by mix | blending 1-10 mass parts of said rubber-modified styrene-type copolymers (C) with respect to 100 mass parts of said styrene- (meth) acrylic-type copolymers (A). Resin composition for film. A heat-shrinkable film obtained from the resin composition for heat-shrinkable film according to any one of claims 1 to 12. The thermal shrinkage rate in the main stretching direction when immersed in hot water at 70 ° C. for 10 seconds is 5% or more, and the thermal shrinkage rate in the main stretching direction when immersed in hot water at 80 ° C. for 10 seconds is 30. The heat-shrinkable film according to claim 13, wherein the heat-shrinkable film is not less than 60% and less than 60%. A bottle comprising the heat-shrinkable film according to claim 14 wound thereon. The bottle according to claim 15, which is a PET bottle having a wall thickness of 0.1 to 0.3 mm.

Images