JP2003041090A - Heat-shrinkable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally shrinkable film that has excellent balance of physical properties, for example, transparency, rigidity, and impact strength, shows good low-temperature shrinkability, as the natural shrinkage is suppressed, and can be readily mounted onto vessels, for example, PET bottles on the beverage charging line. SOLUTION: A resin component including at least two of styrene-conjugated diene block copolymers is used as at lease one layer of the thermally shrinkable film. In addition, the glass transition temperatures of the two block copolymer are adjusted in a specific range, the difference between the glass transition temperatures of these block polymers are adjusted in a specific range and a specific lubricant is mixed to the two resin components forming both of the surface and back layers in specific amounts, respectively.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has an excellent balance of physical properties such as transparency, rigidity, and impact strength, has good low-temperature shrinkage while suppressing natural shrinkage, and has a P
The present invention relates to a heat-shrinkable film that can be easily attached to a container such as an ET bottle or a glass bottle.

[0002]

2. Description of the Related Art Conventionally, heat-shrinkable films used as shrink-wrap packaging and shrink labels for containers have good heat-shrinkability and a good finish after shrinkage, and do not contain halogen substances such as polyvinyl chloride when discarded. From the viewpoint, a styrene-butadiene block copolymer film is used. But,
This film has problems that it is soft and stiff, and has a large natural shrinkage, and various multilayer films have been proposed in order to improve these drawbacks (JP-A-9-114380 and JP-A-11-77916). Further, in order to coat these heat-shrinkable films on containers such as PET bottles and glass bottles, a tubular heat-shrinkable film is covered on a container such as PET bottles in a filling line and then shrinked by heat to form a container. In close contact with. However, when the tubular heat-shrinkable film is put on a container such as a PET bottle, the tubular heat-shrinkable film is caught in the container,
It may not be covered well, and if this phenomenon occurs frequently, there is a problem that the yield of the bottle filling line decreases.

[0003]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has an excellent balance of physical properties such as transparency, rigidity, and impact strength, and has good low temperature shrinkability while suppressing natural shrinkability. It is an object of the present invention to provide a heat-shrinkable film that can be easily attached to a container such as a PET bottle in a filling line.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a resin component containing at least two block copolymers of styrene and a conjugated diene is used in a heat-shrinkable film. At least one layer, the glass transition temperature of the two block copolymers in a specific range, the glass transition temperature difference in a specific range,
Also, by blending a specific amount of a specific lubricant into the resin component forming the front and back layers, the physical properties such as transparency, rigidity, impact strength, etc. are excellent, and the low temperature shrinkability is good while suppressing the natural shrinkability, and filling The present invention has been completed by finding that a heat-shrinkable film can be obtained which can be easily attached to a bottle without covering the bottle when the film is covered on the line.

That is, the present invention relates to (i) a block copolymer having a random copolymer block comprising a styrene monomer and a conjugated diene, and (ii) a styrene monomer in the block copolymer. Mass ratio of body to conjugated diene is 9
5/5 to 60/40 and (iii) a block copolymer (I) having a glass transition temperature in the range of 50 to 110 ° C.
And (iv) a block copolymer having a random copolymer block composed of a styrene monomer and a conjugated diene, wherein (v) the mass of the styrene monomer and the conjugated diene in the block copolymer. The ratio is 95/5 to 60/40,
(Vi) A block copolymer (I) containing a block copolymer (II) having a glass transition temperature 3 (excluding 3 ° C.) to 10 ° C. higher than the glass transition temperature of the block copolymer (I),
And the block copolymer (II) are in the ratio of block copolymer (I) / block copolymer (II) = 10/90 to 90 /
Resin component 100 having at least one layer mainly composed of resin component A of 10 (mass ratio) and forming front and back layers
At least one lubricant selected from (vii) fatty acid amide, (viii) hydrocarbon wax, (ix) fatty acid, and (x) polymethylphenylsiloxane was used in an amount of 0.
The heat-shrinkable film contains 03 to 1.2 parts by mass.

The present invention will be described in detail below. The resin component A of the present invention contains the block copolymer (I) and the block copolymer (II). The block copolymer (I) of the present invention has (i) a random copolymer block composed of a styrene monomer and a conjugated diene, and (ii) a styrene monomer in the block copolymer. The mass ratio of the conjugated diene is 95/5 to 60/40, and (iii) the glass transition temperature is in the range of 50 to 110 ° C. And, the weight average molecular weight thereof is preferably 150,000 to 250,000, and the content of the random copolymer block composed of the styrene-based monomer and the conjugated diene is preferably 30 to 95% by weight in the block copolymer. .

The block copolymer (I) is obtained by polymerizing a styrene monomer and a conjugated diene under a specific condition in an organic solvent using an organic lithium compound as an initiator. Organic solvents include butane, pentane, hexane,
Aliphatic hydrocarbons such as isopentane, heptane, octane and isooctane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane and ethylcyclohexane, or aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene Known organic solvents can be used. The organolithium compound is a compound in which one or more lithium atoms are bonded in the molecule, and examples thereof include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, and t-butyl lithium. Can be used.

The styrene-based monomer used is styrene, α-methylstyrene, p-methylstyrene, p
Although examples thereof include -t-butylstyrene, styrene is preferable. These styrenic monomers are
They may be used alone or in combination of two or more. Moreover, as the conjugated diene used, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene),
2,3-Dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like can be mentioned, but particularly common ones are 1,3-butadiene and isoprene.

The structure of each block portion constituting the block copolymer (I) other than the random copolymer block composed of the styrene monomer and the conjugated diene is a polymer block mainly composed of the styrene monomer. Or a polymer block mainly composed of a conjugated diene, or a tapered block composed of a styrene-based monomer and a conjugated diene.
In order to form a random copolymer block portion composed of a styrene monomer and a conjugated diene, a known randomizing agent may be used, both may be continuously fed to a polymerization vessel, or they may be added little by little alternately. . Further, the structure of the block copolymer (I) used is not particularly limited, and a linear diblock copolymer, triblock copolymer,
Alternatively, a multi-block copolymer having 4 or more blocks,
Alternatively, a star-shaped copolymer in which one end of each of these block copolymers is bonded may be used. Known coupling agents can be used to increase the molecular weight of the linear copolymer or to make it into a star shape. The block copolymer (I)
The glass transition temperature of is in the range of 50 to 110 ° C, preferably 60 to 100 ° C.

The mass ratio of the styrene monomer to the conjugated diene in the block copolymer (I) is 95/5 to 60/40.
Is. If the styrene-based monomer exceeds 95% by mass, the heat shrinkability is poor, and if it is less than 60%, the rigidity is poor and it cannot be put to practical use. Further, the glass transition temperature of the block copolymer (I) is 5
When the temperature is out of the range of 0 to 110 ° C., the natural shrinkability of the resulting heat-shrinkable film is not suppressed, and the low temperature shrinkability is deteriorated, which is not preferable.

Further, the block copolymer (I) used in the present invention has a weight average molecular weight of 150,000 to 250.
It is preferably in the range of 000. When the weight average molecular weight is in the range of 150,000 to 250,000, the moldability into a heat-shrinkable film becomes good, and further the natural shrinkability of the heat-shrinkable film is well suppressed, and the low-temperature shrinkability is further improved. It will be excellent.

The content of the random copolymer block composed of the styrene monomer and the conjugated diene in the block copolymer (I) is preferably 30 to 95% by weight, more preferably 60 to 90% by weight. When the content of the block is in the range of 30 to 95% by weight, the strength and the low temperature heat shrinkability of the heat shrinkable film are further improved. The content of the conjugated diene unit in the random copolymer block composed of the styrene-based monomer and the conjugated diene is preferably 5 to 30% by weight, more preferably 6 to 2
It is in the range of 0% by weight. The content of conjugated diene unit is 5 to 3
When it is in the range of 0% by weight, the low-temperature heat shrinkability of the heat shrinkable film becomes more excellent.

The block copolymer (II) of the present invention comprises (i
v) A block copolymer having a random copolymer block composed of a styrene monomer and a conjugated diene,
(V) The mass ratio of the styrene-based monomer to the conjugated diene in the block copolymer is 95/5 to 60/40, and
i) The glass transition temperature is 3 to 10 ° C. higher (excluding 3 ° C.) than the glass transition temperature of the block copolymer (I). And, preferably the weight average molecular weight is 50,000 to 15
The content of the random copolymer block composed of styrene-based monomer and conjugated diene is preferably 30 to 95% by weight in the block copolymer. The block copolymer (II) can be obtained by the same method as the block copolymer (I). The styrenic monomer and conjugated diene used are the same as in the case of the block copolymer (I).

The structure of each block portion constituting the block copolymer (II) other than the random copolymer block comprising the styrene monomer and the conjugated diene is the same as that of the block copolymer (I). , A single block of a styrene-based monomer or a conjugated diene monomer, or a tapered block of both. The structure of the block copolymer (II) used is not particularly limited, and a linear diblock copolymer, triblock copolymer,
Alternatively, a multi-block copolymer having 4 or more blocks,
Alternatively, a star-shaped copolymer in which one end of each of these block copolymers is bonded may be used. The glass transition temperature of the block copolymer (II) is higher than the glass transition temperature of the block copolymer (I) by 3 (excluding 3 ° C) to 10 ° C, preferably in the range of 60 to 100 ° C.

The mass ratio of the styrene monomer to the conjugated diene in the block copolymer (II) is 95/5 to 60/40.
Is. If the styrene-based monomer exceeds 90% by mass, the heat shrinkability is poor, and if it is less than 60%, the rigidity is poor and it cannot be put to practical use. The glass transition temperature of the block copolymer (II) is
The glass transition temperature of the block copolymer (I) is 3 (3
If it is not higher than 10 ° C, the natural shrinkability of the heat-shrinkable film obtained is not suppressed and the low-temperature shrinkability is deteriorated, which is not preferable. Also preferably, the glass transition temperature is 4 higher than the glass transition temperature of the block copolymer (I).
~ 7 ° C higher. When the difference between the glass transition temperature of the block copolymer (II) and the glass transition temperature of the block copolymer (I) is 3 ° C. or less or exceeds 10 ° C., the effect of suppressing the natural shrinkability of the heat-shrinkable film, Not only is it impossible to achieve both excellent low-temperature shrinkability, but also when a heat-shrinkable film is applied to a container such as a PET bottle,
The film is apt to be caught in the bottle and the film mounting property is deteriorated, which is not preferable.

The ratio of the block copolymer (I) to the block copolymer (II) in the resin component A is as follows: block copolymer (I) / block copolymer (II) = 10/90
90/10 (mass ratio), preferably block copolymer (I) / block copolymer (II) = 30/70 to 7
It is 0/30 (mass ratio). When the ratio of the block copolymer (I) and the block copolymer (II) is within the above range,
It becomes easier to achieve both the effect of suppressing the natural shrinkability of the heat-shrinkable film and the excellent low-temperature shrinkability. Furthermore, when the heat-shrinkable film is put on a container such as a PET bottle, the film mounting property becomes very good. ,preferable.

The block copolymer (I
I) preferably has a weight average molecular weight in the range of 50,000 to 150,000. Weight average molecular weight is 50,000-
When it is in the range of 150,000, moldability into a heat-shrinkable film becomes good, and further, the natural shrinkage of the heat-shrinkable film is well suppressed, and the low-temperature shrinkability becomes further excellent.

The content of the random copolymer block consisting of the styrene monomer and the conjugated diene in the block copolymer (II) is preferably 30 to 95% by weight, more preferably 60 to 95% by weight. 90% by weight. When the content of the block is in the range of 30 to 95% by weight, the strength and the low temperature heat shrinkability of the heat shrinkable film are further improved. Further, the content of the conjugated diene unit in the random copolymer block composed of the styrene monomer and the conjugated diene is preferably 5 to 30% by weight, particularly preferably 6 to
It is in the range of 20% by weight. Conjugated diene unit content of 5
When it is in the range of 30% by weight, the low-temperature heat shrinkability of the heat shrinkable film becomes more excellent.

The method for measuring the glass transition temperature of the block copolymer used in the present invention is not particularly limited, but D
It is measured by a known method such as SC or dynamic viscoelastic spectrum (DMA), and preferably dynamic viscoelastic spectrum (DM).
A) is used. The method for measuring the weight average molecular weight of the block copolymer used in the present invention is a known method such as gel permeation chromatography (GPC), and GPC is preferably used.

Further, in the resin component A of the present invention, in addition to the block copolymer (I) and the block copolymer (II),
If necessary, a styrene copolymer other than (I) or (II) can be contained. As the styrene-based copolymer other than (I) or (II), the same styrene-based monomer as described in the above block copolymers (I) and (II) is used. Homopolymers, copolymers of these styrenic monomers and copolymerizable monomers, high impact polystyrene (HIPS), and further the block copolymers (I) and block copolymers (II Block copolymers other than the above) and the like.

The copolymer of the styrene-based monomer and the monomer copolymerizable therewith includes styrene-methyl methacrylate copolymer, styrene-n-butyl acrylate copolymer, and styrene-methyl methacrylate-polymer. Styrenic monomer such as n-butyl acrylate copolymer-
In the presence of rubber such as (meth) acrylic acid ester copolymer, polybutadiene rubber, styrene-butadiene random copolymer rubber, and styrene-butadiene block copolymer rubber, the styrene monomer and (meth) acrylic ester are copolymerized. Rubber-modified styrene-based monomer- (meth) acrylic acid ester copolymer obtained by polymerization, MBS resin, MB
There is a rubber-like elastic body such as AS resin.

For the MBS resin and MBAS resin, first, polybutadiene or a copolymer rubber latex with styrene containing butadiene as a main component is produced by a known emulsion polymerization method.
At this time, a crosslinking agent or a chain transfer agent may be used. Next, MBS resin is styrene, methylmethacrylate and / or alkyl acrylate in this rubber latex, and MBAS resin is styrene, methylmethacrylate,
It is obtained by adding acrylonitrile and / or alkyl acrylate and performing graft polymerization. MB
The alkyl acrylate used for the AS resin may be the same as that described for the styrene monomer- (meth) acrylic acid ester copolymer.

Among these, as the styrene-based copolymer other than (I) or (II), a homopolymer of a styrene-based monomer, a high impact polystyrene (HIPS), a styrene-n-butyl acrylate copolymer is preferable. Polymer, styrene-
Examples thereof include a methyl methacrylate-n-butyl acrylate copolymer and a styrene-butadiene block copolymer other than the block copolymer (I) and the block copolymer (II).

The method for mixing the block copolymer (I) and the block copolymer (II) and, if necessary, the styrene-based copolymer other than (I) or (II) for obtaining the resin component A is Although not particularly specified, for example, it may be dry blended with a Henschel mixer, a ribbon blender, a V blender, or the like, and may be melted and pelletized with an extruder.

Next, the styrene-based monomer-conjugated diene block copolymer (III) used as the resin component B of the present invention, the styrene-based polymer (IV), and the styrene-based monomer and (meth) acryl. The copolymer (V) comprising an acid ester and / or (meth) acrylic acid will be described.

The styrenic monomer-conjugated diene block copolymer (III) of the present invention contains the styrenic monomer and the conjugated diene as described in the block copolymers (I) and (II) above. It can be obtained by polymerization using the organic solvent and the initiator. Examples of the styrene-based monomer used include the same as those described in the block copolymers (I) and (II). Further, as the conjugated diene used, the same ones as described in the above block copolymers (I) and (II) can be mentioned. The block copolymer used is preferably a block copolymer composed of styrene and butadiene in which the mass ratio of the styrene-based monomer and the conjugated diene is 90/10 to 60/40.

Next, as the styrene-based polymer (IV) used in the present invention, the same styrene-based monomer as described in the above block copolymers (I) and (II) is used,
Examples thereof include homopolymers or copolymers of two or more kinds of these styrene-based monomers, and high impact polystyrene (HIPS).

The copolymer (V) composed of the styrene-based monomer and the (meth) acrylic acid ester and / or (meth) acrylic acid used in the present invention is a styrene-based monomer and a (meth) acrylic. Obtained by polymerizing acid ester and / or (meth) acrylic acid. Examples of the styrene-based monomer include the same styrene-based monomer as described in the block copolymers (I) and (II). On the other hand, examples of the (meth) acrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like. Is methyl methacrylate and / or n
-Butyl acrylate. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more kinds. A combination of methyl methacrylate and n-butyl acrylate is a suitable example. Examples of (meth) acrylic acid include acrylic acid and methacrylic acid. Further, if necessary, other monomers may be used within the range not impairing the object of the present invention. For example, maleic acid, itaconic acid, maleic anhydride or the like is used as the copolymerizable monomer.

In the present invention, the styrenic monomer-conjugated diene block copolymer (III) and the styrenic polymer (I
V), a copolymer (V) comprising a styrene monomer and a (meth) acrylic acid ester and / or (meth) acrylic acid
May form a layer of a multilayer film independently, or may form a layer of a multilayer film mainly with a mixture of two or more kinds. When mixing, the same method as in the case of the resin component A can be used. Preferably,
Styrene-based monomer-conjugated diene block copolymer (II
I) is used alone as the resin component B, and
A layer is preferably formed, and particularly preferably, a block copolymer composed of styrene and butadiene is preferably used alone as the resin component B.

The lubricant used in the present invention is at least one selected from (vii) fatty acid amide, (viii) hydrocarbon wax, (ix) fatty acid, and (x) polymethylphenylsiloxane.

Examples of the fatty acid amide of (vii) include saturated lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like, oleic acid amide, erucic acid amide, ricinoleic acid amide and the like. Unsaturated fatty acid monoamide, N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, methylol stearin Substituted amides such as acid amide, methylolbehenate amide, methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearate Amide phosphoric acid, ethylenebis-isostearic acid amide, ethylene-bis-hydroxystearic acid amide, ethylenebis behenic acid amide,
Hexamethylene bishydroxystearic acid amide,
N, N'-Distearyl adipic acid amide, N, N '
-Saturated fatty acid bisamide such as distearyl sebacic acid amide, ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N'-dioleyl adipate amide, N, N'-dioleyl sebacic acid amide, etc. Aromatic bisamides such as fatty acid bisamides, m-xylylenebisstearic acid amides, N, N'-distearylisophthalic acid amides and the like can be mentioned. These may be used alone or in combination of two or more kinds. good.

Examples of the hydrocarbon wax (viii) include rice wax, beeswax, montan wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, modified polyethylene wax, hardened castor oil, and the like. May be used, or two or more kinds may be used in combination.

Examples of the fatty acid (ix) include the above (vii)
Examples thereof include saturated fatty acids and unsaturated fatty acids used in the production of fatty acid amides, which may be used alone or in combination of two or more kinds. The polymethylphenylsiloxane (x) is not particularly limited, but preferably has a viscosity of 50 to 5,000 centistokes at a temperature of 25 ° C, and more preferably a viscosity of 100 to 3,000 centistokes at a temperature of 25 ° C. It is a thing.

In the present invention, the compounding amount of the lubricant is 0.03 to 100 parts by mass of the resin component forming the front and back layers.
The amount is 1.2 parts by mass, preferably 0.03 to 0.9 parts by mass, and more preferably 0.03 to 0.8 parts by mass.
If the amount is less than 0.03 parts by mass, the slipperiness is insufficient and the film tends to be caught in the bottle when the film is put on the container, which is not preferable. Further, when it exceeds 1.2 parts by mass, transparency is deteriorated and printability is deteriorated, which is not preferable.
The coefficient of dynamic friction of the heat-shrinkable film of the present invention is 0.4
The following is preferable. When the dynamic friction coefficient of the film is 0.4 or less, the film is more difficult to be caught in the bottle when the film is put on the container. The coefficient of dynamic friction referred to in the present invention is a value measured by a method described in JIS K7125 film-to-film and using a stretched film 4 days after being formed as a measurement sample.

In addition, each (co) polymer used in the present invention may optionally contain an antioxidant, a weathering agent, a plasticizer, a tackifier, a colorant, an antistatic agent, a mineral oil, a flame retardant. Additives such as fillers may be added within a range that does not impair the effects of the present invention. The method of blending the additives is not particularly limited, but may be dry blended with a Henschel mixer, a ribbon blender, a V blender, or the like, and may be melted with an extruder and pelletized. Alternatively, it may be added during the production of each polymer, before the initiation of polymerization, during the polymerization reaction, or after the treatment of the polymer.

The plasticizer used in the present invention includes butyl oleate, glycerin monooleic acid and other aliphatic-basic acid esters, dibutyl adipate, diisobutyl adipate, di-n-hexyl adipate, di-adipate. Aliphatic-dibasic acid ester such as 2-ethylhexyl, dibutyl sabacate, di-2-ethylhexyl sabacate, or dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-n-octyl phthalate, di-phthalate Phthalates such as 2-ethylhexyl are preferred. As a preferable addition amount, 0 to 3 parts by mass is preferably added to 100 parts by mass of the resin component A or the resin component B.

The heat-shrinkable film of the present invention is a monolayer film, a two-layer film, a three-layer film, a four-layer film, a five-layer film, or a multilayer film having more layers, but preferably a single-layer film. The film is a film or a film having three or more layers, and particularly preferably a single layer film or a three-layer film. In the case of a three-layer film, the front and back layers may be formed of the resin component A and the intermediate layer may be formed of the resin component B, or the front and back layers may be formed of the resin component B and the intermediate layer may be formed of the resin component A. Good. In the case of a single layer film, the front and back layers are the resin component A, and the resin component A is mixed with a lubricant.

When the heat-shrinkable film of the present invention is a multi-layer film, the above resin components for the front and back layers and the intermediate layer are mixed with a lubricant if necessary and melted in an extruder,
It can be obtained by uniaxially, biaxially or polyaxially stretching it after forming multiple layers in a die or a feed block. In the case of a monolayer film, the resin component A is blended with a lubricant, melted by an extruder, and the extruded sheet is uniaxially, biaxially or polyaxially stretched. Known dies such as a T die and a ring die can be used. As an example of uniaxial stretching, a method of stretching the extruded sheet in a direction orthogonal to the extrusion direction with a tenter,
Examples include a method of stretching the extruded tubular film in the circumferential direction. As an example of biaxial stretching, after stretching the extruded sheet in the extrusion direction with a roll, a method of stretching in a direction orthogonal to the extrusion direction with a tenter, the extruded tubular film in the extrusion direction and the circumferential direction. Examples include a method of stretching simultaneously or separately.

In the present invention, the stretching temperature is 60 to 120.
C is preferred. If it is less than 60 ° C, the sheet or film will be broken during stretching, and if it exceeds 120 ° C, good shrinkage properties cannot be obtained, which is not preferable. The draw ratio is not particularly limited, but is preferably 1.5 to 8 times. 1.
When it is 5 times, the heat shrinkability becomes insufficient, and when it exceeds 8 times, stretching is difficult, which is not preferable. When using these films as heat shrinkable labels or packaging materials,
The heat shrinkage is required to be 20% or more at a temperature of 80 ° C.
If it is less than 20%, a high temperature is required at the time of mounting on a container, which adversely affects the article to be coated, which is not preferable. The thickness of the film is preferably 10 to 300 μm.
Further, in the present invention, an antistatic agent, a lubricant or the like may be applied to the surface in order to improve the surface characteristics of the obtained film.

As the use of the heat-shrinkable film of the present invention, a heat-shrinkable label, a heat-shrinkable cap seal and the like are particularly suitable, but they can also be appropriately used for a packaging film and the like.

[0041]

EXAMPLES Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

[0042]

Examples 1 to 11 and

[Comparative Examples 1 to 19] (a) Raw material polymer Resin component A: Block copolymer (I) The block copolymer shown in Table 1 was used.

Resin component A: Block copolymer (II) The block copolymer shown in Table 1 was used.

The glass transition temperature and weight average molecular weight in Table 1 were measured by the following methods. [Glass transition temperature] The glass transition point of the block copolymer is
It was measured by dynamic viscoelastic spectrum as described below. The block copolymer is heated and pressed into a sheet (thickness 0.2 m
m) was prepared and the sheet was prepared at 23 ° C. and 50% relative humidity,
Conditioned for over 24 hours. Thereafter, with RSA-II manufactured by Rheometrics Co., stress and strain in the tensile direction of 1 Hz were applied to the sheet, tan δ was measured while heating at a rate of 4 ° C./min, and the peak top temperature of the tan δ was measured by glass. The transition temperature was used.

[Weight Average Molecular Weight] The weight average molecular weight of the block copolymer was measured under the following conditions in terms of polystyrene equivalent by GPC method. Solvent (mobile phase): THF, deaerator: ERMA ER
C-3310, Pump: JASCO Corporation PU-980, Flow rate 1.0 ml / min, Autosampler: Tosoh AS-8
020, column oven: Hitachi L-5030,
Set temperature 40 ℃, Column configuration: TSKgurdco manufactured by Tosoh Corporation
lumn MP (× L) 6.0 mm ID × 4.0 cm 1 piece, and TSK-GEL MULTIPORE HXL-M manufactured by Tosoh Corporation
7.8mm ID x 30.0cm 2 pieces, 3 pieces in total, data processing: SIC4
80 data stations. An RI detector L-3350 manufactured by Hitachi, Ltd. was used as the detector.

[0046]

[Table 1]

Resin component B: (III) as shown in Table 2
Styrene-based monomer-conjugated diene block copolymer, (I
V) Styrene-based polymer and (V) styrene-based monomer and (meth) acrylic acid ester and / or (meth) acrylic acid copolymer were used.

[0048]

[Table 2]

Lubricant: (vii) fatty acid amide as shown in Table 3, (viii) hydrocarbon wax, (ix) fatty acid,
(X) Polymethylphenylsiloxane was used.

[0050]

[Table 3]

(B) Production of film Block copolymers (I) and (II) shown in Table 1, Table 2
(III) Styrene-based monomer-conjugated diene block copolymer, (IV) Styrene-based polymer, and (V) Styrene-based monomer and (meth) acrylic acid ester and / or (meth) Using the acrylic acid copolymers and the lubricants shown in Table 3, the heat shrinkability at the blending amount (parts by mass) of the raw material polymer of each layer shown in Tables 4 to 11 and the layer ratio (%) ( Multilayer) film was made. In the case of a multi-layer film, first, the polymer or polymer composition corresponding to each layer is melted in a separate extruder and multilayered in a T-die to a thickness of 0.3 m.
m sheets were molded. In the case of a single layer film, the polymer composition was melted with an extruder and a sheet having a thickness of 0.3 mm was formed with a T die. Then, using a biaxial stretching device manufactured by Toyo Seisakusho, a stretched film was prepared by transversely uniaxially stretching 5 times at a temperature of 90 ° C.

In Tables 4 to 11, the blending amount (parts by mass) of the raw material polymer and the layer ratio (%) of each layer are shown together with the physical properties. Also,
In Comparative Examples 3, 5, 11 and 13, sheet formation was possible, but a stretched film was not obtained.

The physical properties of the film were determined by the following methods. (1) Haze: Measured using a Haze meter (NDH-1001DP type) manufactured by Nippon Denshoku Industries in accordance with ASTM D1003. (2) Thermal contraction rate: It was immersed in warm water of 80 ° C. for 30 seconds and calculated from the following formula. Thermal shrinkage (%) = {(L1-L2) / L1} × 100, where L1: length before dipping (stretching direction), L2: 80 ° C.
Length after shrinkage by dipping in warm water for 30 seconds (stretching direction) (3) Spontaneous shrinkage ratio: 100 mm in length from film, 10 in width
A sample was cut into a size of 0 mm and left in a constant temperature bath in an atmosphere of 30 ° C. for 30 days, and the main shrinkage direction was defined as a percentage (%) calculated from a value obtained by dividing the shrinkage length by the original dimension. (4) Tensile Modulus: According to JIS k6871, Tensilon Universal Testing Machine (RTC-12 manufactured by A & D Co., Ltd.
10A). (5) Film impact: Measured with a film impact tester manufactured by Tester Sangyo using a stretched film. (6) Dynamic Friction Coefficient: Using a stretched film as a sample, JIS
It was measured film-to-film according to the method described in K-7125. The stretched film used as a sample has a temperature of 2
Conditioning was carried out for 4 days after film formation under the conditions of 3 ° C. and humidity of 50% RH.

(7) Film mountability: A stretched film is rolled into a tubular shape, and both ends are bonded with a solvent to form a long tubular shape.
A tubular heat-shrinkable label was produced by cutting the long tubular body at a predetermined interval. Then, 50 cylindrical heat-shrinkable labels are supplied to the automatic label loading device, continuously covered with a 1.5 liter PET container filled internally, and passed through a steam tunnel to shrink, thereby PET labels. I attached it to the bottle. At this time, the number of tubular heat-shrinkable labels that could not be successfully covered by the PET container when 50 tubular heat-shrinkable labels were continuously put on the 1.5-liter PET container by the automatic label attachment device Counting
The films were classified according to the following criteria, and the film mountability was evaluated. ◯: The number of tubular heat-shrinkable labels that could not be properly covered by the PET container was less than 5. ×: The number of tubular heat-shrinkable labels that could not be properly covered by the PET container was 5 or more.

From the physical properties shown in Tables 4 to 11, the film of the present invention has an excellent balance of physical properties such as transparency, rigidity and impact strength and has good heat shrinkability, and further, it can be used in a filling line such as PET bottles. It can be seen that the film can be easily attached to the container.

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

[0059]

[Table 7]

[0060]

[Table 8]

[0061]

[Table 9]

[0062]

[Table 10]

[0063]

[Table 11]

[0064]

EFFECTS OF THE INVENTION According to the present invention, the natural shrinkability is suppressed and the low temperature shrinkability is good, and the physical properties such as transparency, rigidity and impact strength are excellent, and PET is used in the filling line.
It is possible to provide a heat-shrinkable film that can be easily attached to a container such as a bottle or a glass bottle. Further, this film can be used for packaging various articles or can be printed and used as a label.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 5/00 C08K 5/00 // B29K 9:06 B29K 9:06 105: 02 105: 02 B29L 7: 00 B29L 7:00 9:00 9:00 (72) Inventor Shingo Hanari 3-5-1 Asahimachi, Machida, Tokyo Electrochemical Industry Co., Ltd. Central Research Laboratory F-term (reference) 4F071 AA12X AA22X AA75 AA86 AC02 AE11 AF28Y AF61 BC01 4F100 AH01A AH01B AH01C AH01D AH02A AH02B AH02C AH02D AH03A AH03B AH03C AH03D AH06A AH06B AH06C AH06D AJ11A AJ11B AJ11C AJ11D AK12A AK12B AK12C AK12D AK12J AK25B AK25D AK25J AK28A AK28B AK28C AK28D AK28J AL01B AL01D AL02A AL02B AL02C AL02D AL05A AL05C BA02 BA03 BA06 BA07 BA10A BA10B BA10C BA10D BA15 CA19A CA19B CA19C CA19D DA01 DA02 EJ37 GB15 GB90 JA03A JA03C JA05A JA05C JA07A JA07C JK01 JK10 JK16 JN01 YY00 YY00 A YY00B YY00C YY00D 4F210 AA13F AA47 AB07 AB19 AE01 AE08 AG01 AG03 RA03 RC02 RG02 RG04 RG09 RG43 4J002 BB03Y BP01W BP01X CP03Y EA016 EF056 EP006 EP016 EP026 FD17Y FD39 HB1414J026 HA0614J14

Claims (9)

[Claims] 1. A block copolymer having a random copolymer block composed of (i) a styrene monomer and a conjugated diene, and (ii) conjugated with a styrene monomer in the block copolymer. Mass ratio of diene is 95/5 to 60/40
And (iii) a block copolymer having a glass transition temperature in the range of 50 to 110 ° C. and (iv) a random copolymer block composed of a styrene monomer and a conjugated diene. (V) the mass ratio of the styrene monomer to the conjugated diene in the block copolymer is 95/5 to 60/40, and (vi) the glass transition temperature is the block copolymer (I 3) above the glass transition temperature of
(Excluding 3 ° C.) to 10 ° C. higher than the block copolymer (II), and the block copolymer (I) and the block copolymer (II) are contained in a ratio of the block copolymer (I) / block copolymer (II). A heat-shrinkable film composed of a resin mainly composed of a resin component A which is a polymer (II) = 10/90 to 90/10 (mass ratio), and 100 parts by mass of a resin mainly composed of the resin component A. Against (vi
At least one lubricant selected from i) to (x) is used in an amount of 0.
A heat-shrinkable film containing 03 to 1.2 parts by mass. (Vii) fatty acid amide (viii) hydrocarbon wax (ix) fatty acid (x) polymethylphenylsiloxane 2. A block copolymer (III) comprising a styrene monomer and a conjugated diene and a styrene polymer (IV), which comprises at least one layer mainly comprising the resin component A according to claim 1. And a resin component B mainly composed of at least one polymer selected from the copolymer (V) consisting of a styrene monomer and a (meth) acrylic acid ester and / or (meth) acrylic acid. 0.03 of at least one lubricant selected from (vii) to (x) according to claim 1 with respect to 100 parts by mass of a resin component having at least one of the above-mentioned layers and forming the front and back layers. A heat-shrinkable film, characterized by containing 1.2 to 1.2 parts by mass. 3. A resin component A is a block copolymer (I),
The heat-shrinkable film according to any one of claims 1 and 2, which contains a block copolymer (II) and a styrene-based polymer other than (I) or (II). 4. The weight average molecular weight of the block copolymer (I) of the resin component A is 150,000 to 250,000, and the weight average molecular weight of the block copolymer (II) is 50,000 to 15
It is 0000, The heat shrinkable film in any one of Claims 1-3. 5. The content of a random copolymer block comprising a styrene monomer and a conjugated diene is 30 to 95, respectively.
The heat-shrinkable film according to any one of claims 1 to 4, wherein the block copolymer (I) and the block copolymer (II), which are contained in mass%, are used as the resin component A. 6. A resin component B is a block copolymer (III) composed of styrene and butadiene, and the mass ratio of the styrene monomer and the conjugated diene is 90/10 to 60/40. The heat-shrinkable film according to any one of claims 2 to 5. 7. The heat-shrinkable film according to any one of claims 1 to 6, wherein the heat-shrinkable film has a coefficient of dynamic friction of 0.4 or less. 8. The resin component A according to claim 2, wherein the front and back layers are the same.
The heat-shrinkable film, wherein the intermediate layer is formed of the resin component B according to claim 2 or 6. 9. The resin component B according to claim 2, wherein the front and back layers are
The heat-shrinkable film, wherein the intermediate layer is formed of the resin component A according to claim 2 or 3.