JP2001214139A - Thermally shrinkable adhesive covering material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally shrinkable adhesive covering material which, when formed into a tube and put on an adherend, e.g. a glass bottle, is thermally shrunk without causing any trouble and covers the adherend and which, when heated further, completely adheres to the adherend. SOLUTION: This covering material comprises a thermally shrinkable film which has an adhesive layer formed on its one surface to be brought into contact with an adherend. The adhesive layer is formed from an adhesive which, when the material in the shape of a tube is put on an adherend and heated to be shrunk, maintains its tackfreeness until the material is brought into contact with the surface of the adherend and which, when heated further after brought into contact with the adherend, exhibits pressure-sensitive adhesiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable adhesive coating material which is useful as a label to be attached to a container such as a glass bottle, and has an effect of protecting the surface of the glass bottle and preventing scattering of debris at the time of rupture. Things.

[0002]

2. Description of the Related Art A coating material comprising a heat-shrinkable film having an adhesive layer on a surface in contact with an adherend is known (Japanese Utility Model Publication Nos. 53-24845 and 64-15270). However, the conventional coating material having an adhesive layer adheres to the adherend at the same time as or before the heat shrinkage. There has been a drawback that folds and wrinkles are generated, and in some cases, the device cannot be mounted.

[0003]

SUMMARY OF THE INVENTION In the present invention, when a coating material is formed into a tubular shape and attached to an adherend such as a glass bottle, the coating material shrinks without hindrance, and the coating material adheres to the adherend. Another object of the present invention is to provide a heat-shrinkable adhesive coating material that can be completely adhered when further heated.

[0004]

Means for Solving the Problems As a result of intensive studies on the heat-shrinkable adhesive coating material, the present inventors have found that the heat-shrinkable adhesive is used as an adhesive for forming an adhesive layer until the coating material is adhered to the adherend. Have found that the purpose can be achieved by using an adhesive that is substantially non-tacky and becomes tacky at a temperature higher than the heat shrinkage temperature, and based on this finding, form the present invention. Reached.

That is, the present invention relates to a coating material comprising a heat-shrinkable film having an adhesive layer on a surface in contact with an adherend, wherein the adhesive layer forms the coating material into a tubular shape and forms a coating. When attached to the body, heated and shrunk, it maintains non-tackiness until it adheres to the surface of the adherend, and is formed by an adhesive that develops tackiness by further increasing the temperature after adhesion. And a heat-shrinkable adhesive coating material. Here, the non-adhesiveness refers to a property of not feeling sticky when touched by a finger, and maintaining a state in which the adhesive layer surfaces of the two covering materials are superimposed and peeled after being pressed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-shrinkable adhesive coating material of the present invention comprises:
It consists of a heat-shrinkable film and an adhesive layer provided on the surface in contact with the adherend. As a material of the heat-shrinkable film, a transparent resin such as a polyolefin resin, a polystyrene resin, or a polyester resin is used, but a material that can sufficiently withstand the temperature at which the adhesive layer is completely adhered to the adherend. In that respect polyolefin resin,
Particularly, a polypropylene resin having a melting point of 130 ° C. or more is preferable. Further, as a returnable bottle, a polystyrene-based resin becomes cloudy in an alkali resistance test, and a polyester-based resin cracks, so that it cannot be used, and only a polyolefin-based resin can be used.

[0007] The film substrate of the coating material of the present invention may be a single layer or a multilayer, but has at least a three-layer structure, and the outer layer is made of polypropylene, ethylene-propylene random copolymer,
Melting point of ethylene-butene-propylene copolymer 13
It is preferable that the intermediate layer be formed of a polypropylene resin having a temperature of 0 ° C. or higher and the polyolefin resin having a melting point of less than 130 ° C. By forming the intermediate layer with a polyolefin resin having a melting point of less than 130 ° C., the heat shrinkage can be improved. As a polyolefin resin having a melting point of less than 130 ° C., a butene-propylene copolymer,
A polypropylene resin such as a low melting point ethylene-butene-propylene copolymer, a low-density polyethylene, a linear low-density polyethylene, an ethylene-vinyl acetate copolymer, a polybutene resin, and a cyclic olefin resin are used.
When the outer layer has poor adhesion to the polypropylene resin like the polyethylene resin, an adhesive layer made of a mixture of the polyethylene resin and the polypropylene resin may be further provided between the two.

In the case of a multilayer structure as described above, it is preferable to add a petroleum resin to the intermediate layer in order to improve the shrinkage characteristics. This petroleum resin includes aliphatic hydrocarbons,
There are alicyclic hydrocarbons, hydrogenated hydrocarbons and the like, and these are blended in the range of 1 to 40% by weight.

In this film substrate, if necessary,
An ultraviolet absorber and a light stabilizer such as a hindered amine compound can be contained. In particular, when used for returnable bottles, it is necessary to include these additives in order to ensure weather resistance.

In the coating material of the present invention, the thickness of the film substrate is preferably selected within the range of 20 to 100 μm.
If the thickness is smaller than this, it is likely to be broken or scratched, and the effects of protecting the surface of adherends such as glass bottles, preventing fragments from scattering, protecting the printing surface of the coating material, etc. will not be sufficiently obtained, and will be thicker than this. If so, the heat shrinkage is impaired. This coating material must be uniaxially stretched in the lateral direction so that it shrinks in the lateral direction when formed into a tubular shape. The stretching ratio is suitably in the range of 5 to 10 times. It is preferable that at least one surface of the film substrate, the surface in contact with the adhesive layer, or the printed surface is adjusted to a surface tension of 400 μN / cm or more by a roughening treatment, for example, a corona treatment.

Next, as an adhesive for forming an adhesive layer provided on the surface of the heat-shrinkable film which is in contact with the adherend,
In the case of a returnable bottle, a polyurethane-based adhesive having good alkali resistance, acid resistance, and alcohol resistance is preferable, but for other uses, another adhesive, for example, a polyester-based adhesive can also be used. Polyurethane adhesives are usually aqueous solutions or aqueous dispersions thereof,
That is, it is used as a polyurethane emulsion, and this polyurethane emulsion has an anionic charge,
It is composed of an ionic polyurethane emulsion having a cationic charge or a nonionic urethane emulsion having a hydroxyl group.

In the formation of the adhesive layer in the present invention, such a polyurethane emulsion may be used alone, but usually, other polymer emulsions, tackifying resins, thickeners, wetting agents, plasticizers, What mixed and selected organic solvent etc. arbitrarily is used.

The polyurethane emulsion for forming the adhesive layer in the present invention is obtained, for example, by subjecting an aromatic polyester polyol having a carboxyl group and an excess of polyisocyanate such as hexamethylene diisocyanate to urethane formation reaction in an organic solvent. , A diamine or the like, followed by neutralization with a low molecular amine, and then adding water to remove the organic solvent by azeotropic distillation. In addition, JP-A-5-97962, JP-A-8-225780, JP-A-8-33
It can also be prepared with reference to the method described in JP 7767.

Further, these polyurethane emulsions can be obtained as commercial products. Such commercial products include Dispacoll U-42 and U-53,
U-54, KA-8481, KA-8584 (above, trade names of Sumitomo Bayer Urethane Co.), Hydran H
W-111, HW-311, HW-333, HW
-337, HW-350, HW-374, AP-
20, same AP-40F, same AP-60LM, same AP-8
0 (trade names of Dainippon Ink and Chemicals, Inc.), Samprene UXA-3005, UXA-306, and UX-3
12 (above, product names of Sanyo Chemical Industries), Superflex 107M, 110, 126, 130, 1
50, 160, 300, 361, 370, 4
10, 420, 460, 700, 760, 8
20 (the above are trade names of Daiichi Kogyo Seiyaku).

Next, these polyurethane emulsions are charged into an aqueous processing kettle, and an aqueous dispersion of an acrylic polymer, an aqueous dispersion of a polymer such as an aqueous dispersion of an ethylene-vinyl acetate polymer, a tackifying resin such as a rosin ester, a polyvinyl alcohol. , A wetting agent such as succinic ester, and a high-boiling organic solvent such as adipic diester.

As the above-mentioned polyurethane emulsion, a so-called anionic polyurethane emulsion having an anionic charge in a molecule such as a carboxyl group or a sulfonic acid group is preferable from the viewpoint of storage stability and processability. Among them, those having a carboxyl group are most preferable in terms of adhesiveness and reactivity with a crosslinking agent to be used.

The main components of the polyurethane emulsion are one or more polyols selected from polyether polyols, aromatic polyesterols and aliphatic polyesterols as polyols, and fatty acids such as hexamethylene diisocyanate and isophorone diisocyanate as polyisocyanates. It is a polymer obtained by subjecting one or more polyisocyanates selected from aromatic polyisocyanates such as aromatic polyisocyanates, diphenylmethane diisocyanate and toluene diisocyanate to urethane-forming reaction. Among these, the aromatic polyester-ol and the aliphatic polyester-ol as the polyol, and the aromatic polyester-type urethane polymer and the aliphatic polyester-type urethane polymer mainly composed of the aliphatic polyisocyanate as the polyisocyanate have the adhesion to the base film. It is preferable in that it is good. Among them, the most preferable urethane polymer which provides various functions of the present invention is an aromatic polyester type urethane polymer. In particular, an anionic polyurethane emulsion having a carboxyl group is most preferable when the polymer is an aromatic polyester type urethane polymer. Bond CVC880 (manufactured by Konishi Corporation, trade name) is commercially available as an adhesive containing this polyurethane emulsion as a main component.

When forming the adhesive layer of the present invention, it is preferable to use a mixture of a crosslinking agent such as an epoxy compound, an aziridine compound, a polyisocyanate compound, a carbodiimide compound and an oxazoline compound with the above-mentioned polyurethane emulsion. The amount of the crosslinking agent in this case is
0.1 to 50 parts by weight as a pure component is added to 100 parts by weight of the urethane polymer. The preferred range for providing the functions of the present invention is 0.2 to 30 parts by weight. inside that,
The optimum region in consideration of the thermal adhesion and water resistance is 0.5 to 15 parts by weight.

Specific examples of the crosslinking agent used at this time include bisphenol A type or F type epoxy resin, polyglycidyl ether of polyhydric alcohol, N, N, N, '.
Epoxy compounds such as N'-tetraglycidyl meta-xylylenediamine, polyglycidyl ether of sorbitol EO adduct, 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], diphenylmethane-bis-4 4'-N, N'-
Aziridine compounds such as diethylene urea, toluylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude MDI, hexamethylene diisocyanate (HDI), metaxylene diisocyanate (XDI), polymethylene polyphenyl polyisocyanate, and modified products of the above substances And carbodiimide compounds such as diisopropylcarbodiimide, dicyclohexylcarbodiimide, and polycarbodiimide obtained by a decarbonation condensation reaction of an aromatic diisocyanate. As a commercially available product, UCARNKNK XL-29SE (UnionC
arbid company name), Stabaxol (Rei
nChemie), carbodilite (registered trademark of Nisshinbo) and epocross (trade name of Nippon Shokubai)
There is. Among them, epoxy compounds and carbodiimide compounds are preferred in terms of reactivity and adhesiveness. Among them, the most preferred compound providing the functions of the present invention is a carbodiimide compound.

In order to form the adhesive layer of the present invention, a polyurethane emulsion optionally containing a crosslinking agent is applied to a heat-shrinkable film adherend by gravure printing, screen printing, microgravure, reverse, comma coater, or the like. Apply to the surface that will be in contact. The coating amount at this time is 0.3 to 8 g / m ² , preferably 0.5 to 5 g / m ² , and more preferably 1 to 3 g / m ² as a solid content.
Is selected in the range. If it is less than this, sufficient adhesive performance cannot be exhibited, and if it is too large, not only does non-adhesion at room temperature be hindered, but also after adhesion to the adherend, moisture permeates the adhesive layer and alkali resistance decreases. .

When a printing layer is provided on the coating material of the present invention,
It is preferably provided between the film substrate and the adhesive layer, but may be provided on the surface opposite to the adhesive layer if desired. However, for returnable bottles, it is necessary to provide a printing layer between the film substrate and the adhesive layer because the printing layer lacks alkali resistance, acid resistance and alcohol resistance.

Further, when the bottle is mounted on an adherend, the returnable bottle is not resistant to whitening, peeling and shrinking even when immersed in a 4% aqueous solution of sodium hydroxide at 80 ° C. for 5 hours. Acid resistance that does not cause whitening, peeling, or shrinking even when immersed in water for 24 hours, and alcohol resistance that does not cause whitening, peeling, or shrinking even when immersed in a mixed solution of 20% ethanol and 80% water for 24 hours. Therefore, it is necessary to employ full-surface bonding so that water does not enter the bonding surface. After the adhesive is applied to the film substrate in this manner, the adhesive is dried usually at a temperature of 60 to 70 ° C. to form an adhesive layer.

The heat-shrinkable adhesive coating material of the present invention has a heat shrinkage of 30% in the transverse direction (main shrinkage direction) at 100 ° C.
As described above, the length is selected so that the vertical direction (the direction perpendicular to the main shrinkage direction) is 15% or less, preferably 40% or more in the horizontal direction and 10% or less in the vertical direction.

[0024]

Next, the present invention will be described in more detail with reference to examples.
In addition, the measurement of the physical property in each example was performed by the following methods.

(1) Heat Shrinkage A sample was cut into a 100 mm square from the coating material,
After being immersed in a glycerin bath at 00 ° C. for 30 seconds, it was immediately transferred to cold water, and the length L (mm) in the vertical and horizontal directions was measured and calculated according to the following equation.

(2) Non-tackiness Two coating materials cut into a square of 100 mm are overlapped so that the adhesive layers face each other, sandwiched between two glass plates of the same size, and 10 g / cm ² from above. It is left at 40 ° C. for 24 hours while applying a load. Next, after holding at 23 ° C. for 2 hours, the two films were peeled off and evaluated according to the following criteria. ：: Peeling without resistance △: Peelable but peelable ×: Adhesive and not peelable

(3) Adhesion The coating material cut into a square of 100 mm was bonded to a glass plate via an adhesive layer, and heated for 10 minutes while changing the temperature while applying a load of 50 g / cm ^2. , 23 ° C
And leave for 2 hours. Then, the film was peeled from the glass plate. The above heating was performed at an interval of 10 ° C. in the range of 60 ° C. to 120 ° C., and the temperature at which the adhesive was not peeled off was determined. ：: Adhesion temperature is 100 ° C. or more △: Adhesion temperature is 80 to 90 ° C. ×: Adhesion temperature is 70 ° C. or less

(4) Glass Bottle Mounting Property An envelope-shaped coating material with the adhesive layer inside was mounted and mounted using a glass bottle heat shrink film mounting line. The film temperature in that case was about 90 ° C. The results were observed and evaluated according to the following criteria. ○: Can be mounted without any problem, no wrinkles or folds △: Can be mounted, but wrinkles or folds occur ×: Cannot be mounted

(5) Alkali Resistance After the coating material is heat shrunk in a glass bottle and attached, the glass bottle that has been heat-treated at 120 ° C. for 10 minutes is immersed in a 4% aqueous sodium hydroxide solution at 80 ° C. for 5 hours, washed with water, The presence or absence of whitening, peeling and shrinkage was observed and evaluated according to the following criteria. ：: good appearance without whitening, peeling and shrinking △: slight whitening, peeling and shrinking ×: whitening, peeling and shrinking and poor appearance

(6) Acid Resistance A glass bottle heat-treated at 120 ° C. for 10 minutes after mounting the coating material on a glass bottle by heat shrinking is immersed in a hydrochloric acid aqueous solution of PH3 for 24 hours, washed with water, then whitened, peeled and shrunk. Was observed and evaluated according to the same criteria as in (5).

(7) Alcohol Resistance After the coating material is shrink-fitted into a glass bottle and attached, heat-treated at 120 ° C. for 10 minutes, the glass bottle is immersed in a 20% ethanol / 80% water mixture for 24 hours, and washed with water. Later, whitening,
The presence or absence of peeling and shrinkage was observed, and evaluated according to the same criteria as in (5).

Example 1 An ethylene-propylene random copolymer containing 4.6 mol% ethylene (melting point: 135 ° C.) was used as a resin composition mainly composed of a polypropylene copolymer resin constituting an intermediate layer.
38% by weight, 38% by weight of a butene-propylene random copolymer having a butene content of 22.7 mol% (melting point 128 ° C.), a polybutene resin (trade name “Toughmer M-2, manufactured by Mitsui Chemicals, Inc.)
481 ”, melting point 75 ° C) 4% by weight, petroleum resin (Arakawa Chemical Co., trade name“ Alcon P-140 ”, melting point 140 ° C)
20% by weight was extruded from a T-die at 200 ° C. into three layers from separate extruders using the above-mentioned ethylene-propylene random copolymer as both surface layers,
After being cooled and solidified by a cooling roll at 40 ° C., it is ten-fold stretched in the horizontal direction at 60 ° C., and subsequently annealed at 55 ° C. for 5 seconds while relaxing 8% in the horizontal direction in the tenter.
A heat-shrinkable olefin-based film having a thickness of 50 μm was obtained (the thickness of each layer was 5 μm / 40 μm / 5 μm). Then
One side of this film was subjected to a corona treatment. The surface tension of the treated surface was 430 μN / cm. After normal printing was performed on the corona-treated surface of this film, a urethane emulsion (trade name: “Bond CVC” manufactured by Konishi Co., Ltd.) was applied to the printed surface.
880 ") and 100 parts by weight of 10 parts by weight of a carbodiimide-based crosslinking agent (manufactured by Konishi Co., trade name" crosslinking agent D ") and a leveling agent (manufactured by Asahi Glass Co., Ltd., trade name" Surflon 14 ")
1)) The adhesive solution mixed by adding 0.2 parts by weight was applied with a gravure roll (plate depth 32 μ, 180 mesh),
After drying at 60 ° C., a heat-shrinkable olefin film with an adhesive was obtained. The amount of the adhesive applied is 1.5 g / m2 as a solid content.
^{Was 2} . Table 1 shows the physical properties of this film.

Example 2 A heat-shrinkable olefin film with an adhesive was obtained in the same manner as in Example 1 except that the carbodiimide-based crosslinking agent in the formulation of the adhesive solution to be applied was not added. The coating amount of the adhesive was 1.4 g / m ² as a solid content. Table 1 shows the physical properties of this film.

Example 3 In Example 1, a urethane emulsion (trade name: “Bond CVC” manufactured by Konishi Co., Ltd.) having a formulation of an adhesive solution to be applied was used.
880 ") with an adhesive in the same manner as in Example 1 except that 100 parts by weight of a polyester-based emulsion (trade name" Finetex ES-2200 "manufactured by Dainippon Ink and Chemicals, Inc.) was used instead of 100 parts by weight. A heat-shrinkable olefin film was obtained. The application amount of the adhesive was 1.5 g / m ² as a solid content. Table 1 shows the physical properties of this film.

Comparative Example 1 In Example 1, the urethane emulsion (trade name “Bond CVC” manufactured by Konishi Co., Ltd.) having the formulation of the adhesive solution to be applied was used.
880 ") Acrylic adhesive emulsion (manufactured by Konishi, trade name" Bond CE560 ") 1 instead of 100 parts by weight
A heat-shrinkable olefin film with an adhesive was obtained in the same manner as in Example 1 except that 00 parts by weight was used. The application amount of the adhesive was 1.6 g / m ² as a solid content. Table 1 shows the physical properties of this film.

Comparative Example 2 In Example 1, a urethane emulsion (trade name: “Bond CVC” manufactured by Konishi Co., Ltd.) having a formulation of an adhesive solution to be applied was used.
880 ") with an adhesive in the same manner as in Example 1 except that 100 parts by weight of an EVA-based emulsion (manufactured by Chuo Rika Kogyo Co., Ltd., trade name" Lica Bond Aquatex EC-3200 ") was used instead of 100 parts by weight. A heat-shrinkable olefin film was obtained. The amount of adhesive applied is 1.5 as solids.
g / m ² . Table 1 shows the physical properties of this film.

[0037]

[Table 1]

[0038]

The heat-shrinkable adhesive coating material of the present invention, for example, when formed into a tubular shape and mounted on a glass bottle, heat-shrinks without hindrance by heating, adheres to the glass surface, and is further heated. It can be completely adhered, and has alkali resistance, acid resistance, and alcohol resistance, and is particularly suitable for use in returnable glass bottles.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoki Taya 1-1-18 Kyobashi, Chuo-ku, Tokyo Inside C-I Kasei Co., Ltd. (72) Inventor Koji Hayashi 5-3-35 Nishibori, Urawa-shi, Saitama Konishi F term in reference (reference) 4F211 AD09 AE01 AG08 AH55 SA11 SC01 SD04 SG01 SG04 SN06 SN13 SP21 SP40 4J004 AA14 AA17 AB03 CA04 CC02 FA01 FA06

Claims (6)

[Claims] 1. A coating material comprising a heat-shrinkable film having an adhesive layer on a surface in contact with an adherend, wherein the adhesive layer forms the coating material into a tubular shape and attaches the coating material to the adherend. When heated and shrunk, it is non-tacky until it adheres to the surface of the adherend, and is formed of an adhesive that develops adhesiveness by further raising the temperature after adhesion. Heat-shrinkable adhesive coating material. 2. The heat-shrinkable adhesive coating material according to claim 1, wherein the heat-shrinkable film is a uniaxially stretched polyolefin-based film. 3. The heat-shrinkable adhesive according to claim 1, wherein the adhesive layer is formed of an adhesive which is non-tacky at a temperature lower than a shrinkage temperature and becomes adhesive at a temperature higher than the shrinkage temperature. 4. The heat-shrinkable adhesive covering material according to claim 3, wherein the adhesive is a polyurethane resin adhesive. 5. The heat-shrinkable adhesive coating material according to claim 4, wherein the polyurethane resin adhesive is a coated and dried product of a polyurethane emulsion containing a crosslinking agent. 6. The heat-shrinkable adhesive coating material according to claim 5, wherein the crosslinking agent is a carbodiimide compound.