JP3482533B2 - Heat sealable label - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat sealable label. The heat-sealable label is a label to be attached to the molded container at the same time when molding the container by hollow molding of resin, injection molding, differential pressure molding, or the like, or a container such as a cup container or yogurt. It is useful as a heat-sealable lid material. In particular, it is suitable as an in-mold molding label used when molding a container by injection molding and at the same time molding a container (see FIG. 1 described later) in which the label is attached to the container in an overlapped state. .

[0002]

2. Description of the Related Art Conventionally, in order to integrally mold a resin molding container with a label, a label (including a blank label) is previously inserted in a mold, and then injection molding, hollow molding, differential pressure molding, foaming. The container is molded by molding or the like, and the container is painted (so-called in-mold molding). In-mold molding labels used in such cases include gravure-printed resin film, offset multicolor-printed synthetic paper, or polyethylene laminated on the backside of an aluminum foil, and gravure-printed aluminum on the surface of the foil. Labels are known.

Conventionally, as a method for producing this type of label, printing is performed on the surface of a sheet-like base material such as a synthetic resin film of pulp paper, polyethylene terephthalate, polyamide, polypropylene, synthetic paper, metal foil and the like, and the back surface thereof. A low melting point resin film such as low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer can be directly extrusion-melt laminated on the side, or like polyvinyl acetate or ethylene-vinyl acetate copolymer. There has been known a method of obtaining a label for in-mold molding having a heat-sealing property by coating a solvent-type adhesive having a low melting point resin dissolved in a solvent or a heat-sensitive resin latex adhesive with a gravure coater or the like.

In the above label manufacturing method, when the low-melting resin film is directly extrusion-melt-laminated to provide the heat-sealable layer, heat is applied to directly laminate the high-melting resin film on the substrate. There were drawbacks such as wrinkles and lumps on the base material. In addition, when coating with a solvent-based adhesive, there is a risk of fire and poisoning due to an organic solvent, and there is a problem that equipment cost for solvent recovery increases, leading to cost increase.

[0005]

DISCLOSURE OF THE INVENTION The present invention does not require an organic solvent for coating an adhesive, has a simple label manufacturing process, has a low manufacturing cost, and is excellent when used for in-mold molding or the like. It is intended to provide a heat-sealable label having heat-seal adhesive force.

[0006]

The inventors of the present invention have conducted various studies to solve the above-mentioned problems, and as a result, applied a specific photocurable resin composition to a sheet-like base material and applied a coating layer thereof. The object could be achieved by curing the resin by irradiation with active energy rays to form a heat-sealable resin layer.

That is, according to the present invention, 1 part of maleic anhydride is added to 100 parts by weight of at least one copolymer selected from (A) a copolymer of an aromatic vinyl compound and a conjugated diene and a hydrogenated product thereof. To the maleic anhydride-modified copolymer (a) obtained by addition reaction of 20 to 20 parts by weight of the general formula (I)

[0008]

[Chemical 2] Containing 3 to 30% by weight of an esterified product obtained by reacting a hydroxyl group-containing (meth) acrylate (b), and 97 to 70% by weight of (B) a reactive diluent comprising a compound having a (meth) acryloyl group. 0.5 to at least one surface of the sheet-like substrate, the photocurable resin composition
A heat-sealable label is obtained by applying a coating layer having a thickness of up to 40 μm and then curing the applied layer by irradiation with active energy rays to form a heat-sealable resin layer on the sheet-shaped substrate.

The maleic anhydride-modified copolymer (a) as a raw material for producing the esterified product (A) constituting the photocurable resin composition used in the present invention is a copolymer of an aromatic vinyl compound and a conjugated diene. It is obtained by addition-reacting 1 to 20 parts by weight of maleic anhydride with 100 parts by weight of at least one copolymer selected from the polymers and hydrogenated products thereof. In that case, if the amount of maleic anhydride added is less than 1 part by weight, the adhesive strength between the resin molded in the container and the label and the label becomes insufficient. Further, it is difficult to add the maleic anhydride in an amount exceeding 20 parts by weight, unreacted maleic anhydride remains in the esterified product, and purification thereof takes time. Further, if the maleic anhydride remaining in a large amount is used, the adhesive strength between the container and the label is lowered.

The above maleic anhydride-modified copolymer (a)
As a copolymer of an aromatic vinyl compound and a conjugated diene as a raw material for producing and a hydrogenated product thereof, styrene-butadiene copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene copolymer, styrene -Isoprene-styrene block copolymers and hydrogenated products of these copolymers. Among these, styrene-butadiene-styrene block copolymer,
Most preferred are styrene-isoprene-styrene block copolymers and hydrogenated products thereof.

The addition reaction of at least one copolymer selected from the copolymer of an aromatic vinyl compound and a conjugated diene and its hydrogenated product with maleic anhydride is usually carried out using a radical initiator. However, since the reaction itself is known, its detailed description is omitted. The maleic anhydride-modified copolymer (a) thus obtained preferably has a weight average molecular weight of about 1,000 to 200,000, particularly 10,000 to 10
Thousands are more preferable. If its molecular weight is too low,
The adhesive strength of the heat-sealable label of the final product becomes insufficient, and if it is too high, the esterified product (A) is difficult to dissolve in the compound having a (meth) acryloyl group as a reactive diluent, and some gel The remaining amount may make it difficult to apply it to the base material sheet, or reduce the heat seal strength between the container and the label.

Next, a maleic anhydride-modified copolymer (a)
Contains a hydroxyl group-containing (meta) represented by the general formula (I).
The acrylate (b) is reacted to form an esterified product (A). In the reaction, one equivalent of the maleic anhydride group of the maleic anhydride-modified copolymer (a) is equivalent to a hydroxyl group-containing (meth) acrylate (b). It is desirable that both compounds are reacted at a ratio of 1 to 20 equivalents, preferably 2 to 10 equivalents.

Examples of the hydroxyl group-containing (meth) acrylate (b) represented by the above-mentioned general formula (I) in this reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and N.
-Methylol (meth) acrylamide, 2-hydroxyethyl acrylate-6-hexanolide addition polymer, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate and the like can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate is most preferable.

The reaction temperature in this reaction is usually 20.
To 150 ° C., preferably 50 to 120 ° C., using an acid or basic compound such as sulfuric acid, paratoluenesulfonic acid, zinc chloride, pyridine, triethylamine, dimethylbenzylamine, etc. as a catalyst for promoting the reaction. Good. In this reaction, in order to prevent the formation of the homopolymer of the hydroxyl group-containing (meth) acrylate (b) represented by the general formula (I), the reaction is carried out under an atmosphere of oxygen or air to give hydroquinone, hydroquinone monomethyl ether, phenothiazine. It is preferable to add an appropriate amount of a polymerization inhibitor such as to the reaction system. The reaction is preferably carried out in a suitable organic solvent, and examples of the organic solvent include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, cellosolve acetate and the like. Further, a compound containing a (meth) acryloyl group having a function of dissolving an esterified product (A) as a reactive diluent described later can be used as the solvent.

The esterified product (A) thus obtained is dissolved in a reactive diluent composed of a compound having a (meth) acryloyl group to give 3 parts of the esterified product (A).
The photocurable resin composition used in the present invention contains 30 to 30% by weight and a reactive diluent of 97 to 70% by weight. In addition,
When a compound having a (meth) acryloyl group is used as a reaction solvent when producing the esterified product (A), it goes without saying that the reactive diluent may not be added again.

The compound having a (meth) acryloyl group as the reactive diluent (B) is a compound having a (meth) acryloyl group and capable of dissolving the esterified product (A). , Either can be used.

For example, as the compound having one (meth) acryloyl group in the molecule, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-
Ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate,
Stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, tricyclodecanyl (meth) acrylate, isobornyl (meth)
Examples thereof include acrylate, phenol polyethylene glycol (meth) acrylate, phenol polypropylene glycol (meth) acrylate, nonylphenol polyethylene glycol (meth) acrylate and nonylphenol polypropylene glycol (meth) acrylate.

The compounds having two (meth) acryloyl groups in the molecule include 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate and neopentyl glycol di (meth). )
Examples thereof include acrylate and tricyclodecane dimethanol di (meth) acrylate.

Further, as the compound having three or more (meth) acryloyl groups in the molecule, trimethylolpropane tri (meth) acrylate, trimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Examples thereof include erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

Among these compounds having a (meth) acryloyl group in the molecule, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate,
(Meth) acrylate having an alicyclic hydrocarbon group such as dicyclopentenyloxyethyl (meth) acrylate, tricyclodecanyl (meth) acrylate, isobornyl (meth) acrylate and tricyclodecanedimethanol di (meth) acrylate Most preferred. These compounds having a (meth) acryloyl group may be used alone or as a mixture of two or more kinds.

As described above, the photocurable resin composition of the present invention contains the esterified product (A) and the reactive diluent (B). It can be varied within a wide range depending on the type of the reactive diluent, the use of the heat-sealable label, etc., but the esterified product (A) is added to the total amount of both.
Is 3 to 30% by weight, preferably 5 to 25% by weight, and the reactive diluent (B) is 97 to 70% by weight, preferably 95 to 7%.
It is 5% by weight.

If desired, a photopolymerization initiator may be added to the photocurable resin composition. Examples of the photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, diethoxyacetophenone, hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, benzophenone and Michler's ketone. The compounding amount of the photopolymerization initiator is 10
0.1 to 10 parts by weight, preferably 1 to 0 parts by weight
5 parts by weight.

The photocurable resin composition obtained as described above is applied to at least one surface of a sheet-like substrate in an amount of 0.5 to 40.
After being coated to a thickness of μm, the coating layer is cured by irradiation with active energy rays to form a heat-sealable resin layer on the above-mentioned sheet-shaped substrate, whereby the heat-sealable label of the present invention is obtained.

Various materials can be used as the sheet-shaped substrate. For example, pulp paper, coated paper, synthetic paper consisting of stretched film of inorganic filler-containing resin, polyethylene terephthalate, polyamide, polypropylene, polycarbonate, saponified ethylene-vinyl acetate copolymer, polystyrene, synthetic resin film such as polyvinyl chloride, Examples include laminated products of these various sheets, and aluminum vapor deposition or silicon oxide vapor deposition of these various sheets. As the base material of the label for overlap seal,
It is particularly preferable to use offset printing, gravure printing, silk screen printing, or other such printing, aluminum vapor deposition, or metal foil press-bonding. The thickness of the sheet-shaped substrate is generally 8 to 290 μm, preferably 10 to 230 μm. The sheet-shaped substrate may be previously subjected to corona discharge treatment, ozone treatment or anchor coating agent treatment in order to enhance the adhesiveness of the photocurable resin composition.

The photocurable resin composition may be applied to the sheet-shaped substrate by using an offset printing machine or the like, and other usual application methods such as air knife coating, blade coating, bar coating and gravure coating. coat,
A coating method such as curtain coating or roll coating can be used. The coating amount varies depending on the type of the photocurable resin composition and the required performance such as the heat-seal adhesive strength of the resulting label, but generally 0.5 to 40 g /
m ² , preferably 1 to 30 g / m ² . If the coating amount is too small, sufficient heat seal strength will not be obtained,
On the other hand, if the coating amount is too large, it is difficult to apply the coating material uniformly in a single coating step by the usual coating method, and if the coating amount is applied twice, the processing cost increases and the cost increases.

The heat-sealable label of the present invention can be obtained by curing the coating layer by irradiation with active energy rays to form a heat-sealable resin layer. The active energy rays include ultraviolet rays and electron rays. Examples of the ultraviolet ray source include a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, a tungsten lamp, and the like. 50 to 1000 mj / cm ² , preferably 10 emitted from these ultraviolet ray sources.
Ultraviolet rays having an energy of 0 to 800 mj / cm ² are used.

Examples of electron beams used for curing include various electron beam accelerators such as Cockloft-Walton type, Van de Graaff type, resonance transformer type, insulating core transformer type, direct type, dynamitron type, high frequency type and the like. To be 50 to 1000 KeV emitted from these electron beam sources, preferably 1
An electron beam having an energy of 00 to 500 KeV is used.

The heat-sealable label of the present invention obtained as described above is printed on the surface to which the photo-curable resin composition is applied and the reaction surface thereof by using gravure printing or an offset printing machine, if necessary. Can be preferably used as a label for in-mold molding in which a container is molded by blow molding, injection molding, differential pressure molding or the like, and at the same time a label is attached to the molded container. Further, when molding a cup-shaped container, it is also useful as an overlap seal label in which the ends of the label are overlapped and used (see FIG. 1). The heat-sealable label itself can also be used as a lid material for a container such as cup noodles.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples.

Example 1 Synthesis of Maleic Anhydride Modified Copolymer: A hydrogenated styrene-butadiene-styrene block copolymer (Shell Chemical Co., Ltd.) was placed in a glass flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer. Product name Clayton G-1
652) 100g and xylene 200g,
After the system was replaced with nitrogen and the temperature was raised to 140 ° C., 15 g of maleic anhydride and 3 g of dicumyl peroxide were added to 15 g of xylene.
The solution dissolved in 0 g was added dropwise over 8 hours. further,
After reacting at the same temperature for 1 hour, the system was cooled to around room temperature and poured into 1300 g of acetone to precipitate an anhydrous hydrogenated maleic styrene-butadiene-styrene block copolymer. Subsequently, this precipitate was filtered off and dried to obtain a maleic anhydride-modified copolymer in the form of white powder. Infrared absorption spectrum measurement and neutralization titration of this modified copolymer revealed that the content of maleic anhydride was 1.5% by weight.

Preparation of photo-curable resin composition: Anhydrous maleated hydrogenated styrene-butadiene-styrene obtained by the above copolymer synthesis was placed in a glass flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer. 15 g of the block copolymer, 85 g of isobornyl acrylate, and 0.05 g of hydroquinone monomethyl ether were charged and the temperature was raised to 120 ° C. under an air stream to dissolve them. 2-
Hydroxyethyl acrylate 1.6g and dimethylbenzylamine 0.75g were added, and it was made to react at the same temperature for 5 hours. As a result of infrared absorption spectrum analysis of the obtained product, 67% of maleic anhydride grafted with the maleic anhydride-modified copolymer was found to be a 2-ester of 2-hydroxyethyl acrylate. Therefore, the esterification product obtained in this case contained 15.8 g of the esterified product (A).

The resulting esterification product {15.8 g of the esterified product (A) and 8% of isobornyl acrylate as a reactive diluent is then obtained.
3 g of hydroxycyclohexyl phenyl ketone (CIBA-GEIGY trade name, Irgakiure 184) was dissolved in 5 g of the compound contained therein to prepare a photocurable resin composition.

In Example 1 of Table 1 below, the charged amount of the raw material for preparing the photocurable resin composition, the produced amount of the esterified product (A), and the weight composition of the photocurable resin composition are described.

Manufacture of synthetic paper: Melt flow rate (MF
R) is 0.8 g / 10 min polypropylene (melting point about 16
81% by weight, high-density polyethylene 3% by weight, and calcium carbonate powder 16% by weight with an average particle size of 1.5 μm
The composition mixed with was melt-kneaded with an extruder set at a temperature of 270 ° C., then extruded into a sheet from a die and cooled with a cooling device to obtain an unstretched sheet. Next, this sheet was heated again to a temperature of 140 ° C. and then stretched 5 times in the machine direction.

Separately, 54% by weight of polypropylene having a MFR of 4.0 g / 10 min (melting point of about 164 ° C.) and 46% by weight of calcium carbonate powder having an average particle size of 1.5 μm were mixed at 270 ° C. After kneading with an extruder set to a temperature of, this is extruded into a sheet form from a die and laminated on both sides of the 5 times stretched film obtained above,
A laminated film having a three-layer structure was obtained.

Then, this laminated film having a three-layer structure is formed into 6
After cooling to 0 ° C., it is heated again to a temperature of 160 ° C., and stretched 7.5 times in the transverse direction using a tenter to give 165
Annealing treatment is performed at a temperature of 60 ° C., cooling is performed to a temperature of 60 ° C., the ears are slit, and a three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching) having a wall thickness of 80 μm (B / A / B = 16
μm / 48 μm / 16 μm) was obtained. The void content of each layer of this synthetic paper is (B / A / B = 30
% / 33.7% / 30%).

Production of heat-sealable label: The product name, manufacturer, contents and design were printed on the surface of the synthetic paper produced as described above by using the oxidation polymerization type offset printing ink.

Then, the photocurable resin composition prepared in the above Preparation Example was applied to the opposite side (back surface) of the printing surface of this printed synthetic paper using a bar coater so that the coating amount was 5 g / m ^2. Then, the coated synthetic paper is passed under a high pressure mercury lamp having an output of 7.5 kW and an output density of 120 W / cm, which is installed perpendicular to the passage direction of the synthetic paper, and the irradiation energy is 484 mj / cm ^2. It was irradiated with ultraviolet rays and cured. The obtained heat-sealable synthetic paper had a total thickness of 85.2 μm, and the cured resin layer (heat-sealable resin layer) had a thickness of 5.2 μm.

The synthetic paper having the cured resin layer (heat-sealable resin layer) thus obtained was cut into a size of 50 mm in length and 170 mm in width to obtain an in-mold molding label for injection molding.

In-mold injection molding:
Inside the injection mold for molding a cup container with a wall thickness of 1 mm, a diameter of 50 mm and a height of 60 mm, make sure that the printed surface of the label is in contact with the wall surface of the mold, and both ends of the label are 13 mm wide. It was wrapped and mounted in a ring-shaped cross section.

Then, polypropylene (Mitsubishi Yuka Co., Ltd., trade name Mitsubishi Polypro MA-3) which had been previously heated and melted at a temperature of 230 ° C. was injected with an injection pressure of 2400 Kgf / cm ² ,
Injection molding machine (Sumitomo Heavy Industries, Ltd., trade name Promat P-165 / 7) under the molding conditions of an injection speed of 200 mm / sec, a mold cooling water temperature of 40 ° C., a mold cooling time of 8 seconds, and a holding time of 2 seconds.
5) was injection-molded to obtain a cup container in which the labels are attached to the container in a state where some of the labels overlap each other as shown in FIG.

The overlapped portion and the non-overlapped portion of the label of this container were cut in the height direction of the container to have a width of 10 mm and a length of 55 mm, respectively, to obtain two test pieces. .

The adhesive strength between the labels for the overlapping test pieces and the adhesive strength between the label and the container body for the non-overlapping test pieces were measured by Orientec Co., Ltd. The T-shaped peel strength was measured with a tensile tester under the condition of a tensile speed of 200 mm / min. The results are shown in Table 2.

The synthetic paper having the heat-sealing resin layer obtained above was cut into A4 size,
After stacking the sheets and applying a load of 50 kg on them, after leaving them in a thermostatic chamber at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, the load is removed and the blocking state of the label is examined.
The blocking resistance was evaluated according to the following criteria. The results are shown in Table 2.

B: No blocking is observed. B: Slight blocking is observed, but it is easily peeled off without causing any practical problems. X: Blocking occurs, which is a problem in practice.

Examples 2 to 6 The photocurable resin composition was prepared in the same manner as in Example 1 except that the amount of raw material for preparing the photocurable resin composition was changed as shown in Table 1. Using the obtained photocurable resin composition, a heat-sealable label was manufactured in the same manner as in Example 1 except that the heat-sealable label was used. Mold injection molding was performed, and the same tests were conducted. The results are shown in Table 2.

Comparative Example 1 15 g of hydrogenated maleated anhydride styrene-butadiene-styrene block copolymer obtained in the synthesis of the maleic anhydride-modified copolymer of Example 1 was added to 85 g of isobornyl acrylate and hydroxycyclohexyl phenyl ketone. 3 g of (CIBA-GEIGY company trade name Irgakiure 184) was added and dissolved to prepare a photocurable resin composition. A heat-sealable label was produced in the same manner as in Example 1 except that this photocurable resin composition was used, and in-mold injection molding was performed in the same manner, and the same tests were conducted. The results are shown in Table 2.

Comparative Example 2 To 100 g of isobornyl acrylate, 3 g of hydroxycyclohexyl phenyl ketone (Irgakiure 184, trade name of CIBA-GEIGY) was added to obtain a photocurable resin composition. A heat-sealable label was produced in the same manner as in Example 1 except that this photocurable resin composition was used, and in-mold injection molding was performed in the same manner, and the same tests were conducted. The results are shown in Table 2.

[0049]

[Table 1]

[0050]

[Table 2]

As can be seen from Table 2, the labels of the examples have remarkably high adhesive strength with the cup container and adhesive strength between the labels, and also have excellent blocking resistance.

[0052]

EFFECTS OF THE INVENTION This heat sheet label does not require an organic solvent for adhesive coating, has a simple label manufacturing process, has a low manufacturing cost, and is used particularly as a label for in-mold molding. In addition, remarkably high heat seal adhesive strength can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a container injection-molded by using the heat-sealable label of the present invention as an in-mold molding label.

[Explanation of symbols]

1 Container obtained by injection molding 2 Heat sealable label 3 Heat-sealable label wrap

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyuki Hata 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Co., Ltd. Yokkaichi Research Institute (56) Reference JP-A-63-150304 (JP, A) JP Japanese Unexamined Patent Publication No. 4-211413 (JP, A) Japanese Unexamined Patent Publication No. 1-391091 (JP, A) Japanese Unexamined Patent Publication No. 4-172491 (JP, A) Japanese Unexamined Patent Publication No. 3-88579 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G09F 1/00-5/04 B29D 9/00 B32B 1/00-35/00 C08F 283/01 C08F 290/00-290/14 C08F 299/00-299/08 C08C 19 / 00-19/44 C08F 6/00-246/00 C09J 1/00-5/10 C09J 9/00-201/10

Claims (2)

(57) [Claims] 1. 1 to 20 parts by weight of maleic anhydride per 100 parts by weight of at least one copolymer selected from (A) a copolymer of an aromatic vinyl compound and a conjugated diene and a hydrogenated product thereof. To the maleic anhydride-modified copolymer (a) obtained by addition reaction of the general formula (I) Containing 3 to 30% by weight of an esterified product obtained by reacting a hydroxyl group-containing (meth) acrylate (b), and 97 to 70% by weight of (B) a reactive diluent comprising a compound having a (meth) acryloyl group. 0.5 to at least one surface of the sheet-like substrate, the photocurable resin composition
A heat-sealable label obtained by applying a thickness of -40 μm and then curing the applied layer by irradiation with active energy rays to form a heat-sealable resin layer on the sheet-shaped substrate. 2. At least one copolymer selected from a copolymer of an aromatic vinyl compound and a conjugated diene and a hydrogenated product thereof is a styrene-butadiene copolymer or a styrene-butadiene-styrene block copolymer. The heat-sealable label according to claim 1, which is a combination, a styrene-isoprene copolymer, a styrene-isoprene-styrene block copolymer, or a mixture of one or more hydrogenated products thereof.