JP3405576B2 - Thermal release film and release method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to metal, glass, fiber,
The present invention relates to a heat-peelable film which exhibits high adhesion to various adherends such as paper and plastics and can be peeled from the adherend by heating, and a peeling method for peeling the adherend from the film.

[0002]

2. Description of the Related Art A heat-adhesive film has simplicity, high workability and adhesive strength. Therefore, the heat-adhesive film is used in a wide range of fields, such as adhesion of various parts in automobile assembly, adhesion of fibers in the field of apparel, adhesion of coated steel plates and plastic plates in the field of low-electricity, and adhesion of labels to packaging containers. Has been done. Further, the heat-adhesive film does not have the problems found in solvent-based adhesives and water-based adhesives, and therefore its demand is increasing more and more. That is, the solvent-based adhesive lowers the working environment and causes environmental pollution, and the water-based adhesive requires a long time to develop the drying speed and the adhesive strength, and the productivity decreases.

On the other hand, in recent years, from the viewpoints of environmental protection and resource saving, the need for recycling of various products has been emphasized. Therefore, it would be useful if a technique for efficiently separating two adherends adhered by an adhesive after use could be established. However, not only solvent-based adhesives and water-based adhesives, but also heat-adhesive films are originally used for the purpose of firmly adhering adherends. Therefore, it is difficult to achieve both high adhesive strength and separation of the adherend. In particular, the heat-adhesive film is
Due to its high adhesive strength, it is extremely difficult to separate the adherend from the adhesive layer. In addition, the same or different 2
When adhering two adherends, the peeling surface of the adhesive layer to the adherend cannot be controlled, and it is difficult to selectively peel the adherend and reuse the adherend. Further, not only a large external force is required to separate the two adherends,
Even if peeled off, the adhesive adheres to the adherend and the reusability of the adherend is impaired.

In Japanese Patent Laid-Open No. 274783/1990, a composition containing heat-expandable microcapsules and a pressure-sensitive adhesive is applied to a substrate and the microcapsules are thermally expanded by heating to form a bubble-containing pressure-sensitive adhesive layer. A pressure sensitive adhesive tape is disclosed. This adhesive tape enhances the adhesion to the uneven surface of the printed board when masking the non-plated portion of the printed board, and can prevent the plating solution from entering. However, the above-mentioned prior art document does not disclose not only the purpose of expanding the microcapsules by heating to enhance the adhesion to the substrate, but also the peeling of the adherend by heating. Further, since the pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer formed on one surface of a base material layer such as paper or film for the purpose of surface protection or the like, two adherends cannot be bonded to each other.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a heat-peelable film and a peeling method which can adhere an adherend with high adhesive strength and can easily peel the adherend by heating. It is in.

Another object of the present invention is to provide a heat-peelable film capable of selectively peeling an adherend and a peeling method.

[0007]

The present inventors have made earnest studies to achieve the above-mentioned object, and as a result, when a film having an adhesive layer containing a heat-adhesive resin and heat-expandable microcapsules is used, a large external force is applied. In other words, the present invention has been completed by finding that the adherend can be easily peeled from the adhesive layer by utilizing the thermal expansion force of the microcapsules.

That is, the heat-peelable film of the present invention is
The adhesive polymer layer containing the heat-adhesive resin and the heat-peelable layer containing the heat-expandable microcapsules and the heat-adhesive resin are formed in two layers. is at least one member selected from olefin polymers, polyesters and polyamides, the melting point of the thermal adhesive resin is 40 to 150 ° C., adhesion Po
The melting point of the heat-adhesive resin in the limmer layer is
Higher than the melting point of the resin. Further, the foaming temperature of the thermally expandable microcapsule is 15 to 100 ° C. higher than the melting point of the thermally adhesive resin of the heat release layer.

Further, in the peeling method of the present invention, in the structure in which the first adherend is adhered to the adhesive polymer layer of the heat-peelable film and the second adherend is adhered to the heat-peelable layer. Then, the heat release layer is heated to a temperature not lower than the foaming temperature of the heat-expandable capsule to separate the heat release layer from the second adherend.

In the present specification, the term "film" is used to include all substantially flat structures which may be referred to as a sheet by those skilled in the art. "Melting point"
Is a thermal differential scanning calorimeter (DSC), JIS K
According to 7121, it means a melting peak temperature (Tpm) when measured at a temperature rising rate of 10 ± 1 ° C./min. Further, the “foaming temperature” means the temperature at which the heat-expandable microcapsules start to thermally expand.

The film of the present invention comprises a plurality of layers, an adhesive polymer layer is formed on one surface, and a thermal peeling layer having thermal adhesiveness and expanding on heating is formed on the other surface. Has been done.

The adhesive polymer layer contains various polymers capable of forming a film and exhibiting high adhesive strength to an adherend. Such polymers include polymers constituting various adhesives such as thermoplastic adhesives, thermosetting adhesives, polymerization adhesives, photo-curing adhesives, pressure-sensitive adhesives, and hot-melt adhesives. Solvent-free adhesives, solvent-based adhesives, water-based adhesives, emulsion-based adhesives, etc.

Examples of the polymer for the thermoplastic adhesive include vinyl acetate polymers, ethylene-vinyl acetate polymers, vinyl alcohol polymers, polyvinyl acetals, polyvinyl butyral, polyvinyl ether, and other vinyl polymers; ethylene-ethyl acrylate. Copolymer; Acrylic polymer; Vinyl acetate- (meth) acrylate copolymer; Maleic anhydride copolymer; Polyamide; Polyester; Thermoplastic polyurethane; Silicone polymer; Natural rubber, Polyisobutylene, Nitrile rubber, Examples include rubber-based polymers such as chloroprene rubber, styrene-phthaldiene copolymer, styrene-acrylonitrile copolymer, and styrene-butadiene-acrylonitrile copolymer. Examples of the polymer of the thermosetting adhesive include amino resin, phenol resin, epoxy resin, polyurethane, unsaturated polyester, and thermosetting acrylic resin. The polymerizable adhesive includes, for example, a polyfunctional (meth) acrylate and an oligomer, and the photocurable adhesive includes a polyfunctional (meth) acrylate and an oligomer, an epoxy (meth) acrylate, a polyester (meth). ) Acrylate, polyurethane (meth) acrylate and the like. Examples of the polymer of the pressure-sensitive adhesive include polyvinyl ether, acrylic polymer, silicone polymer, the rubber polymer and the like. These polymers may be used alone or in combination of two or more and used as a composite adhesive.

The polymer contained in the adhesive polymer layer is
It can be appropriately selected according to the type of adherend. The adhesive polymer layer may be composed of a solvent-based adhesive, a water-based adhesive or an emulsion-based adhesive, but from the viewpoint of workability and suppression of environmental pollution, a pressure-sensitive adhesive, a hot-melt adhesive It is preferable to use a solventless adhesive such as, especially a hot-melt type heat-adhesive resin.

Examples of the heat-adhesive resin include various resins having heat-adhesiveness, such as olefin polymers, polyesters and polyamides. These heat-adhesive resins can be used alone or in combination of two or more.

Examples of the heat-adhesive olefin-based polymer include polyethylene, ethylene-butene-1 copolymer, ethylene- (4-methylpentene-1) copolymer, ethylene-hexene-1 copolymer, ethylene- Vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ethyl copolymer, polypropylene (atactic polypropylene, etc.), propylene-butene-1 copolymer, ethylene- Examples thereof include propylene copolymers, ethylene-propylene-butene-1 copolymers, ethylene-propylene-diene copolymers, and modified polyolefins such as maleic anhydride-modified polyethylene and maleic anhydride polypropylene. Preferred olefin-based polymers include ethylene-vinyl acetate copolymer,
Ethylene-ethyl acrylate copolymer, amorphous polyolefin (for example, amorphous polypropylene),
Amorphous olefins (such as low molecular weight aliphatic hydrocarbons) are included.

As the diol component constituting the heat-adhesive polyester, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-butanediol, Aliphatic diols such as 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, and polymethylene glycol; 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and these alkylenes. Examples thereof include alicyclic diols such as adducts with oxides; bisphenol A, naphthalene diols, and aromatic diols such as adducts thereof with alkylene oxides. Preferred diol components include aliphatic diols.

Examples of the dicarboxylic acid component constituting the heat-adhesive polyester include unsaturated aliphatic dicarboxylic acids such as maleic acid and fumaric acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, suberic acid and dodecanoic acid. Saturated aliphatic dicarboxylic acids such as; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic anhydride, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid Are exemplified. Preferred dicarboxylic acid components include aliphatic dicarboxylic acids or their acid anhydrides, especially saturated aliphatic dicarboxylic acids or their acid anhydrides.

The heat-adhesive polyester is not limited to the above-mentioned diol component and dicarboxylic acid component, and if necessary, a unit of polyhydric alcohol such as glycerin, trimethylolpropane, pentaerythritol, trimellitic anhydride, or pyromellitic anhydride. It may contain a unit of polyvalent carboxylic acid such as meritic acid.

The preferred heat-adhesive polyester is a polyester containing, as a constituent unit, one of an aliphatic diol and an aliphatic dicarboxylic acid, and in particular, a completely aliphatic polyester containing an aliphatic diol and an aliphatic dicarboxylic acid as constituents. Includes polyester. Preferred thermoadhesive polyesters often contain units of saturated aliphatic carboxylic acids.

Examples of the heat-adhesive polyamide include nylon 6, nylon 11, nylon 12, nylon 1
3, nylon 610, nylon 612, nylon 616
Etc., and copolymer nylon using these nylon raw materials (for example, nylon 6-12). Preferred polyamides include nylon 11, nylon 12,
Nylon 6-12 and the like are included.

The melting point of these heat-adhesive resins is usually 4
It is often 0 to 150 ° C, preferably about 50 to 130 ° C.

A feature of the present invention is that the heat release layer includes a heat adhesive resin and heat expandable microcapsules. Therefore, by utilizing the heat adhesiveness of the heat adhesive resin, the adherend can be firmly adhered to the heat release layer of the heat peelable film, and when heated above the foaming temperature of the microcapsules, a large external force acts. Without using the expansion force of the unfoamed microcapsules, the adherend can be easily peeled from the heat peelable film. Note that the heat-peelable layer containing the foamed capsule has a lower adhesive strength to an adherend, unlike a pressure-sensitive adhesive that flows under pressure.

As the heat-adhesive resin for the heat release layer, the heat-adhesive resins exemplified above can be used. Preferred heat-adhesive resins include the same olefin polymers, polyesters and polyamides as described above.

The heat-expandable microcapsules are composed of cells and expandable inclusions. Capsule cells are various polymers that regulate the permeation of inclusions, for example, vinylidene chloride-based copolymers having high gas barrier properties (vinylidene chloride-acrylonitrile copolymer, vinylidene chloride- (meth) acrylic acid ester copolymer, Vinylidene chloride-vinyl acetate copolymer, etc.), ethylene-vinyl alcohol copolymer, acrylic polymer, thermoplastic resin such as thermoplastic polyurethane, and the like. The inclusion contained in the cell is usually heated by heating at about 100 to 150 ° C.
A gas or liquid that expands about 10 to 100 times, preferably about 20 to 50 times is included. As the inclusion, for example,
Examples include hydrocarbons such as propane, butane, gentane, and hexane, halogenated hydrocarbons such as CFCs, and the like. The average particle size of the capsule is usually 1 to 50 μm, preferably about 10 to 40 μm.

Such heat-expandable microcapsules are
For example, it is commercially available under the trade name "Matsumoto Microsphere" manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. and the trade name "IX Pancel" manufactured by Nippon Philite Co., Ltd.

The foaming temperature of the heat-expandable microcapsules is
Usually, it is 50 to 160 ° C, preferably about 70 to 150 ° C. Among such heat-expandable microcapsules,
It is important to select microcapsules having a foaming temperature higher than the melting point of the heat-adhesive resin that constitutes the heat release layer. Foaming temperature T of preferable heat-expandable microcapsules
Is usually 10 ° C. or higher, preferably 15 to 100 ° C. higher than the melting point Tmp of the heat-adhesive resin that constitutes the heat release layer. When the foaming temperature of the heat-expandable microcapsules approaches the melting point of the heat-adhesive resin, the capsules foam when mixing the heat-adhesive resin and the capsules, forming a heat-peelable layer or heat-bonding, and the adhesive strength of the heat-peelable layer decreases However, if the foaming temperature is too high, a large amount of heat energy is required for peeling due to heating, workability is reduced, and the adherend may be deformed or damaged by heat depending on the type of the adherend. .

The content of the microcapsules in the heat release layer can be selected according to the kind of the heat adhesive resin, etc.
Usually, it is about 1 to 50% by weight, preferably about 5 to 45% by weight. Microcapsule content is 10-40% by weight
It is often a degree. When the content of the heat-expandable microcapsules is less than 1% by weight, the thermal peeling property is not sufficient, and when it exceeds 50% by weight, the adhesive strength between the thermal peeling layer and the adherend is lowered to obtain a practical adhesive strength. Is difficult.

When a heat-adhesive resin is used as the polymer of the adhesive polymer layer, the heat-adhesive resin of the heat release layer may be the same as or different from the heat-adhesive resin of the adhesive polymer layer. Good. The melting points of the heat-adhesive resin of the adhesive polymer layer and the heat-adhesive resin of the heat-peelable layer may be the same or different. When a heat-adhesive resin having a higher melting point than the heat-adhesive resin of the heat-peelable layer is used as the heat-adhesive resin of the adhesive polymer layer, the heat-adhesive resin of the heat-peelable layer is preferentially softened or melted by heating. The adherend can be easily peeled off from the heat peeling layer.

The adhesive polymer layer and / or the heat release layer are
Various conventional additives, such as polymerization catalysts, cross-linking agents, stabilizers (antioxidants, UV absorbers, heat stabilizers, etc.), plasticizers, fillers, tackifiers, etc., as long as the adhesiveness is not impaired. (For example, petroleum resin, terpene resin, dicyclopentadiene resin, coumarone-indene resin and hydrogenated resins thereof), lubricant, antistatic agent, antiblocking agent, colorant, flame retardant, etc. Good. In addition,
When a heat-adhesive resin is used, the adhesive polymer layer and / or the heat-releasing layer often contains the above-mentioned stabilizer, plasticizer, filler, tackifier, colorant, antistatic agent and the like.

The film thickness of each layer of the adhesive polymer layer and the heat peeling layer can be appropriately set depending on the application within a range that does not impair the adhesive strength and the heat peeling property, for example, 5 to 500 μm, preferably 10 to 150 μm. Is.

The heat-peelable film of the present invention may be composed of a plurality of layers including at least the adhesive polymer layer and the heat-peelable layer, and between the adhesive polymer layer and the heat-peelable layer, For example, a base material layer such as paper, cloth, non-woven fabric, metal foil or film may be interposed. If necessary, a layer such as an anchor coat layer or an undercoat layer may be formed between the adhesive polymer layer and / or the heat release layer and the base material layer. The heat-peelable film is often composed of two layers, the adhesive polymer layer and the heat-peelable layer.

The heat-peelable film of the present invention can be produced using a composition containing an adhesive polymer and a composition containing a heat-adhesive resin and heat-expandable microcapsules. Each of the above compositions can be used as a liquid containing a solvent, and when it is a thermoadhesive resin, it can be used as a melt obtained by heating and melting.
The composition for forming the heat-peelable layer can be prepared, for example, by adding the heat-expandable microcapsules to a solvent solution of the heat-adhesive resin or a heated melt of the heat-adhesive resin and mixing them. The heat-expandable microcapsules are added to and mixed with the heated melt at a temperature not lower than the melting point of the heat-adhesive resin and lower than the foaming temperature of the heat-expandable microcapsules.

The heat-peelable film contains the above-mentioned compositions.
It can be formed by subjecting to a conventional film forming method, for example, a coextrusion molding method such as an inflation method or a T die method, a coating method such as a hot melt coating method, or the like. In addition,
In the coating method, the adhesive polymer layer composition may be applied to one surface of the substrate, and the heat release layer composition may be applied to the other surface, and the release treatment is performed with silicone or wax. The composition for the adhesive polymer layer and the composition for the heat release layer may be applied to the release surface of the substrate in any order. Alternatively, the film-like heat-peelable layer and the film-like adhesive polymer layer may be prepared in advance, and both may be heat-laminated or dry-laminated with an adhesive or the like to be laminated. Furthermore, the composition for the heat release layer may be coated on the film constituting the adhesive polymer layer.

The film of the present invention may be stretched if necessary, and the surface of the adhesive polymer layer and / or the heat release layer may be surface-treated by corona discharge treatment or the like, if necessary. Good.

When the adherend is adhered by the heat-peelable film of the present invention, the adhesion between the adhesive polymer layer and the first adherent may be dry or normal temperature depending on the kind of adhesive polymer and its form. Alternatively, it can be carried out by an appropriate method such as curing under heating, heat adhesion, pressurization or light irradiation. Further, the heat release layer and the second adherend can be bonded by thermal bonding. The first and second adherends may be the same or different.

When the adhesive polymer layer is composed of a thermoadhesive resin, it can be firmly adhered to the first adherend by heat adhering at a temperature higher than the melting point of the thermoadhesive resin and cooling. In addition, the thermal bonding temperature between the thermal release layer and the second adherend is
Depending on the type of the heat-adhesive resin or the adherend, it can be appropriately selected within a temperature range not lower than the melting point of the heat-adhesive resin constituting the heat release layer and lower than the foaming temperature of the microcapsules. In such a method, since the capsule of the heat release layer is in a non-foamed state at the time of adhering to the second adherend, the heat-adhesive resin of the heat release layer allows the second adherend to have high adhesive strength. Can bond the body. In the case of using a thermoadhesive resin, at the time of adhering to the adherend, at least one of the film and the adherend may be heated, or the film and the adherend may be laminated and heated and pressed. .

In the method of the present invention, as described above, in the structure in which the first adherend is adhered to the adhesive polymer layer and the second adherend is adhered to the heat release layer, the heat release layer is used. And the second
When it is peeled off from the adherend, it is heated to a temperature not lower than the foaming temperature of the heat-expandable capsule of the heat-peeling layer. At the time of peeling off the second adherend, at least the heat peeling layer may be heated,
The entire structure may be heated.

By such heating, the heat-expandable microcapsules foam inside the heat-peelable layer, destroy the heat-peelable layer, and greatly reduce the adhesive strength of the heat-peelable layer to the second adherend. Therefore, by a simple method of heating to above the foaming temperature of the heat-expandable microcapsules, while maintaining high adhesive strength between the adhesive polymer layer and the first adherend, a large external force can be applied to the heat release layer. The second adherend and the heat release layer are separated without peeling off the second adherend.

The heating temperature for peeling is not particularly limited as long as it is at least the foaming temperature of the capsule, but is usually 2 to 50 ° C. higher than the foaming temperature, preferably 5 to 3
It is a high temperature of about 0 ° C. The heating time depends on the heating temperature and the like, but is, for example, 1 second to 5 minutes, preferably 10 seconds to 3
It's about a minute.

The heat-peelable film of the present invention is preferably used for adhering various members that require separation of adherends, such as metal, glass, ceramics, fibers, paper, plastics and wood.

[0042]

EFFECTS OF THE INVENTION According to the heat-peelable film and the peeling method using the same of the present invention, the adhesive polymer layer constituting one surface layer and the heat-peelable layer constituting the other surface layer are utilized to obtain high heat resistance. The adherend can be adhered with an adhesive strength, and the heat-expandable microcapsules of the heat release layer can be expanded by heating, so that the adherend can be easily peeled from the heat release layer. Further, the adherend can be selectively peeled off by the thermal peeling layer.

[0043]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples.

Reference Example 1 70 parts by weight of an aliphatic polyester (manufactured by Daicel Chemical Industries, Ltd., trade name "Plaxel P4", melting point 60 ° C.) 70 parts
After melting at ℃, thermal expansion microcapsules (Matsumoto Yushi-Seiyaku Co., Ltd., trade name "Microsphere F-30",
A molten mixture was prepared by mixing with 40 parts by weight of a particle size of 10 to 20 μm and a foaming temperature of 80 ° C.). This molten mixture was applied onto release paper using a hot melt coater to give a thickness of 30
A heat release layer having a thickness of μm was formed.

Next, the aliphatic polyester is heated,
A film having a total film thickness of 50 μm is obtained by melting and applying a layered coating on the surface of the heat-releasing layer using a hot melt coater to form a heat-adhesive polymer layer having a thickness of 20 μm, cooling to room temperature, and then releasing the release paper. Was produced.

A stainless steel plate was placed on the surface of the heat release layer of the obtained adhesive film, a polyester film was placed on the surface of the heat adhesive polymer layer, and the temperature was 70 ° C. and the pressure was 5
Thermal adhesion was performed under the conditions of kg / cm ² and time of 30 seconds, and the adhesive strength was measured. Also, heat treatment at a temperature of 90 ° C. for 60 seconds,
The adhesive strength after heating was measured and the peeled surface was observed.

Reference Example 2 Amorphous polyolefin (manufactured by Ube Lexen Co., Ltd.,
Product name "APAO-RT2715", melting point 107 ° C) 7
0 parts by weight is heated and melted at 120 ° C., and heat-expandable microcapsules (Matsumoto Yushi-Seiyaku Co., Ltd., trade name “Microsphere F-80S”, particle size 16 to 32 μm, foaming temperature 1
(35 ° C.) 30 parts by weight were added and mixed to prepare a molten mixture. The composition for the heat release layer and the amorphous polyolefin for the heat-adhesive polymer layer that does not contain the heat-expandable microcapsules are extruded by subjecting them to a T-die co-extrusion machine at 120 ° C. A film having an adhesive polymer layer thickness of 50 μm and a thermal release layer thickness of 50 μm was produced.

A polypropylene plate was overlaid on the surface of the heat release layer of the obtained adhesive film, a polypropylene film was overlaid on the surface of the adhesive polymer layer, and the temperature was 120 ° C. and the pressure was 1 k.
Thermal adhesion was performed under the conditions of g / cm ² and time of 90 seconds, and the adhesive strength was measured. Also, heat treatment at a temperature of 150 ° C. for 60 seconds,
The adhesive strength after heating was measured and the peeled surface was observed.

Example 1 Nylon 12 (manufactured by Daicel Huls Co., Ltd., trade name “Daiamide 750”, melting point 100 ° C.) was subjected to a T-die extrusion molding machine at 130 ° C., and heat-bonded to a film thickness of 100 μm. The film which comprises a conductive polymer layer was produced.

Aliphatic polyester (manufactured by Daicel Chemical Industries, Ltd., trade name "Placcel P4", melting point 60 ° C.) 8
0 parts by weight is heated and melted at 70 ° C., and thermally expanded microcapsules (Matsumoto Yushi-Seiyaku Co., Ltd., trade name “Microsphere F-85”, particle size 16 to 32 μm, foaming temperature 140
(.Degree. C.) 20 parts by weight was added and mixed to prepare a molten mixture.
This molten mixture was applied to one surface of the nylon 12 film using a hot melt coater to give a film thickness of 30
A heat release layer having a thickness of μm was formed to produce an adhesive film.
A stainless steel plate was placed on the surface of the heat-peelable layer of the obtained adhesive film, and a copper foil was placed on the surface of the heat-adhesive polymer layer, and heat-bonded under the conditions of a temperature of 120 ° C., a pressure of 10 kg / cm ² , and a time of 40 seconds. The adhesive strength was measured. Then the temperature
Heat treatment was performed at 150 ° C. for 60 seconds to measure the adhesive strength after heating and observe the peeled surface. Comparative Example 1 The mixture of the aliphatic polyester prepared in Reference Example 1 and the heat-expandable microcapsules was used without laminating with the heat-adhesive polymer layer, and the film thickness was 50 μm in the same manner as in Reference Example 1.
A film composed of m heat release layer was prepared.

A stainless steel plate was placed on one side of the obtained film, and a polyester film was placed on the other side of the obtained film and heat-bonded in the same manner as in Reference Example 1 to measure the adhesive strength. Next, heat treatment was performed under the conditions of a temperature of 90 ° C. and a time of 60 seconds, the adhesive strength after heating was measured, and the peeled surface was observed.

Comparative Example 2 The amorphous polyolefin of Example 2 was used for extrusion molding to obtain an adhesive film (film thickness 100 μm) composed of an adhesive polymer layer.

A polypropylene plate was placed on one side of the adhesive film, and a polypropylene film was placed on the other side of the adhesive film, and heat-bonded in the same manner as in Example 2 to measure the adhesive strength. Then, heat treatment was performed at a temperature of 150 ° C. for a time of 60 seconds, the adhesive strength after heating was measured, and the peeled surface was observed.

The adhesive strength is 180 ° peeling, speed 3
The measurement was performed under the condition of 00 mm / min (kg / 25 mm).

The results are shown in Table 1. In addition, in Table 1,
The heat peelability was evaluated according to the following criteria.

◯: Peeling between the heat-peelable layer and the adherend Δ: Peeling site varies depending on the location, the peeling layer adheres to the stainless steel plate and the polyester film, and the peeling surface cannot be specified. ×: Peeling is impossible

[0057]

[Table 1] As shown in Table 1, the film of Comparative Example 1 has a low adhesive strength after heating and exhibits heat releasability, but it is difficult to selectively peel the film. In addition, the film of Comparative Example 2 has high adhesive strength even after heating and does not exhibit thermal peelability. On the other hand, in the film of Example 1, the adhesive strength is greatly reduced by heating, and the film has excellent thermal peeling property, and the adherend can be selectively peeled off.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-43851 (JP, A) JP-A-3-64381 (JP, A) JP-A-5-32943 (JP, A) JP-A-2- 92977 (JP, A) JP 55-48273 (JP, A) JP 54-156043 (JP, A) Actually opened 62-64739 (JP, U) Actually opened 63-22872 (JP, U) 52-62362 (JP, U) JP-B-49-22949 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09J 7/00 B32B 7/06 C09J 5/06

Claims (5)

(57) [Claims] 1. A heat-peelable film comprising two layers of an adhesive polymer layer containing a heat-adhesive resin and a heat-peelable layer containing heat-expandable microcapsules and a heat-adhesive resin, said heat-peelable film comprising: The heat-adhesive resin of the adhesive polymer layer and the heat-peelable layer is at least one selected from olefin polymers, polyesters and polyamides, respectively, and the melting point of the heat-adhesive resin is 40 to 150 ° C.
The melting point of the heat-adhesive resin of the adhesive polymer layer is
A heat- peelable film having a higher melting point than the heat-adhesive resin . 2. The foaming temperature of the heat-expandable microcapsules is
15-100 from the melting point of the heat-adhesive resin of the heat release layer.
The heat-peelable film according to claim 1, which has a high temperature. 3. The heat-adhesive resin is an ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, amorphous polyolefin, amorphous olefin, aliphatic polyester, nylon 11, nylon 12, nylon 13 The heat-peelable film according to claim 1, which is at least one selected from the group consisting of nylon 610, nylon 612, nylon 616, and copolymer nylon using the nylon raw material, and has a melting point of 50 to 130 ° C. 4. The heat-peelable film according to claim 1, wherein the content of the heat-expandable microcapsules in the heat-peelable layer is 1 to 50% by weight. 5. The first adherend adheres to the adhesive polymer layer of the heat-peelable film according to claim 1, and the second adherend adheres to the heat-peelable film.
In the structure to which the adherend is adhered, the peeling method of heating the thermal peeling layer to a temperature equal to or higher than the foaming temperature of the thermally expandable capsule to separate the thermal peeling layer and the second adherend.