JP2003238910A - Heating releasable thermoset adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating releasable thermoset adhesive film which shows releasability by heating, and can effectively prevent breaking of an adherend and retaining glue on the adherend. <P>SOLUTION: The heating releasable thermoset adhesive film comprises a heat resistant base and an acrylic thermoset adhesive layer formed on at least one side of the base, the layer containing a thermoset acrylic adhesive polymer having an epoxy group and a carboxy group in a molecule. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-peelable thermosetting pressure-sensitive adhesive film. More specifically, it relates to a heat-peelable thermosetting adhesive film useful for masking, for example.

[0002]

BACKGROUND OF THE INVENTION One of the categories of adhesives is the pressure sensitive adhesive as is well known. This pressure-sensitive adhesive has tack at room temperature, and can generally exhibit an adhesive force that can be put to practical use immediately by simply applying pressure without activating it with water, a solvent, heat or the like. Pressure sensitive adhesives are also called pressure sensitive adhesives. Also,
Many of them include processed films (including tapes, straps and sheets. Hereinafter, the adhesive processed as described above is also referred to as “adhesive film” or “adhesive sheet”.

A typical adhesive film uses an acrylic adhesive as a main component. This is because the acrylic pressure-sensitive adhesive is generally excellent in weather resistance. In particular, when the acrylic pressure-sensitive adhesive is crosslinked (hereinafter referred to as “crosslinked acrylic pressure-sensitive adhesive”), it also has heat resistance. An example of a cross-linking acrylic adhesive is disclosed in US Pat. No. 3,284,423. This cross-linked acrylic adhesive is
(A) Acrylic ester 35 to 75 having 6 to 15 carbon atoms
%, (B) 10-60% by weight of alkyl acrylate such as methyl acrylate or ethyl acrylate,
(C) 0.1 to 10% by weight of an acid component such as (meth) acrylic acid, itaconic acid or crotonic acid, and (d) 0.1 to 10% by weight of glycidyl (meth) acrylate,
Self-crosslinking at room temperature or by heating. As a result, the cross-linking acrylic pressure-sensitive adhesive can achieve both cohesive force / holding force at high temperature and sufficiently high adhesive force. Further, preferably, 1 to 3% by weight of glycidyl (meth) acrylate is contained to give the crosslinked acrylic pressure-sensitive adhesive a desired cohesive force.

On the other hand, the pressure-sensitive adhesive film may require removability such that it can be easily peeled off after use, such as a masking tape. Such heat-peelable pressure-sensitive adhesive films are disclosed, for example, in JP-B-51-24534, JP-A-56-61467, JP-A-56-61468, JP-A-56-61469, and JP-A-56-61469. 60-2
As disclosed in JP-A-52681, JP-A-63-186791 and JP-A-2-305878, a heat-foaming agent or a heat-expanding material is further included. The heat-foaming agent or heat-expandable material should be removed by easily peeling the heat-peelable pressure-sensitive adhesive film from the adherend by reducing the adhesion area between the heat-peelable pressure-sensitive adhesive film and the adherend by heat treatment after use. You can On the other hand, the heat-foaming agent and the heat-expanding material tend to divide the heat-peelable pressure-sensitive adhesive film by heat treatment. As a result, the pieces of the heat-peelable pressure-sensitive adhesive film are likely to remain on the adherend.

Further, Japanese Unexamined Patent Publication No. 10-25456 discloses a pressure-sensitive adhesive sheet which can be easily peeled and removed by heating similar to the above, and generally 100 parts by weight of a pressure-sensitive adhesive base polymer and It has a pressure-sensitive adhesive layer containing 900 parts by weight of a thermosetting compound and 0.1 to 10 parts by weight of a heat polymerization initiator. The pressure-sensitive adhesive sheet enables strong adhesion when used by the base polymer. However, once the pressure-sensitive adhesive sheet is heat-treated after use, the adhesive strength is lowered and the adhesive sheet can be easily peeled off. The heat-curable compound is three-dimensionally crosslinked by being heated to 30 to 150 ° C. in the presence of a heat polymerization initiator such as an organic peroxide.
This is because the adhesiveness of the adhesive sheet is reduced. Although a low molecular weight compound or oligomer having at least two carbon-carbon double bonds is usually used as the heat-curable compound, such a low molecular weight compound or oligomer remains in the pressure-sensitive adhesive layer without crosslinking. It is easy, and as a result, there is a tendency for adhesive residue to remain during peeling.

Further, Japanese Patent Publication No. 56-500889 discloses a pressure-sensitive adhesive sheet which can be easily peeled and removed by light irradiation instead of heating. More specifically, the pressure-sensitive adhesive sheet usually has an epoxy equivalent of 400 to 900 including an epoxy (oxirane ring) -containing acrylic pressure-sensitive adhesive polymer such as a copolymer of glycidyl (meth) acrylate, and the onium It contains an effective amount of an ion photoinitiator such as a salt compound. Similar to the above, this pressure-sensitive adhesive sheet also enables strong adhesion during use. Further, once the sheet is irradiated with light after use, the pressure-sensitive adhesive sheet can be easily peeled off due to a decrease in adhesive strength. This is because the photoinitiator accelerates the ionic ring-opening polymerization reaction of the oxirane ring and three-dimensionally crosslinks the oxirane ring-containing monomer of the adhesive sheet. As described above, in order to peel and remove the photocrosslinkable pressure-sensitive adhesive sheet from the support or the adherend, it is often necessary to irradiate light through the support and / or the adherend. Therefore, the use of this pressure-sensitive adhesive sheet is accompanied by a constraint that the support and / or the adherend must have a light-transmitting property, and it is desirable as long as it can be avoided.

[0007]

Therefore, the present invention is capable of avoiding the above-mentioned restrictions on use and effectively preventing damage to an adherend and adhesive residue on the adherend. An object is to provide a heat-peelable thermosetting pressure-sensitive adhesive film that can be used.

[0008]

The present invention has been made to solve the above-mentioned problems, and according to the present invention, a heat-resistant base material and an acrylic heat-resistant material provided on at least one surface of the base material are provided. A heat-peelable thermosetting adhesive film comprising a curable adhesive layer, wherein the acrylic thermosetting adhesive layer has an epoxy group and a carboxyl group in the molecule. Contains a polymer,
A heat-peelable thermosetting adhesive film is provided. Such a pressure-sensitive adhesive film exhibits peelability when heated, and does not cause damage to the adherend and adhesive residue on the adherend during peeling.
Further, since light such as ultraviolet rays is not required to exhibit the peeling property, a base material which is opaque to light can be used.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-peelable thermosetting pressure-sensitive adhesive film of the present invention (hereinafter referred to as "pressure-sensitive adhesive film") will be described below in accordance with preferred embodiments. However, it will be easily understood by those skilled in the art that the present invention is not limited to these. The pressure-sensitive adhesive film of the present invention includes a heat-resistant base material and an acrylic thermosetting pressure-sensitive adhesive layer provided on at least one surface of the heat-resistant base material. The heat resistant substrate supports the acrylic thermosetting pressure-sensitive adhesive layer. The heat-resistant substrate may support the acrylic thermosetting pressure-sensitive adhesive layer on only one side, or may support the acrylic thermosetting pressure-sensitive adhesive layer on both sides thereof. Usually, the heat-resistant substrate does not necessarily have a light-transmitting property, and it is preferable to appropriately select the material according to the heating temperature of the pressure-sensitive adhesive film, that is, the curing temperature of the acrylic thermosetting pressure-sensitive adhesive layer. For example, polyethylene terephthalate (PET) can be selected as the desired heat resistant substrate if the heating or curing temperature is less than about 150 ° C. Further, the heating temperature or the curing temperature is 150 to
At 200 ° C, the preferred heat resistant substrate comprises polyetherimide, polyether sulfone, polyethylene naphthalate or polyphenylene sulfide. Furthermore, if the heating temperature or curing temperature is about 200 ° C. or higher,
The preferred heat resistant substrate comprises polyetheretherketone, polyamideimide or polyimide. Particularly, considering the availability and chemical stability, PET, polyethylene naphthalate, polyphenylene sulfide, and polyimide are desirable because they have high versatility. In consideration of handling and availability, the heat resistant substrate preferably has a thickness of 1 to 200 μm, and more preferably 1 to 25 μm.

The acrylic thermosetting adhesive layer contains a thermosetting acrylic adhesive polymer having an epoxy group and a carboxyl group in the molecule. The thermosetting acrylic pressure-sensitive adhesive polymer generally has a glass transition temperature of −80 to 25 ° C. in order to have tackiness.

According to the present invention, the thermosetting acrylic adhesive polymer has the following formula:

[0012]

[Chemical 1]

As shown in (3), the heating rapidly forms a three-dimensional crosslink between the epoxy group and the carboxyl group and cures. As a result, the pressure-sensitive adhesive film has reduced adhesiveness and can be easily peeled off from the adherend.

A preferred thermosetting acrylic adhesive polymer contains 2 to 50 mol% of epoxy groups and the molar ratio of said epoxy groups to carboxyl groups is 0.15 to 4.0.
Is in the range. When the epoxy group is contained in an amount of more than 50 mol%, the pressure-sensitive adhesive film has low adhesiveness to an adherend and is easily peeled off during use. On the other hand, the epoxy group is contained in less than 2 mol% or the above molar ratio is 0.15 to 4.
If it is out of the range of 0, the thermosetting reaction of the thermosetting acrylic pressure-sensitive adhesive polymer tends to be insufficient. As a result, the adhesive strength of the pressure-sensitive adhesive film is less likely to decrease, and it becomes more difficult to peel again. The thermosetting acrylic pressure-sensitive adhesive polymer preferably has a weight average molecular weight of 10,000 to 1,000,000 as measured by gel permeation chromatography in terms of polystyrene. This is because when the weight average molecular weight is about 10,000 or less, the cohesive force of the thermosetting acrylic pressure-sensitive adhesive polymer is low and the adhesive residue is likely to remain.
On the other hand, if the weight average molecular weight is about 1,000,000 or more, the viscosity of the thermosetting acrylic pressure-sensitive adhesive polymer is too high, so that stable coating is difficult.

A typical thermosetting acrylic adhesive polymer is a copolymer derived from a mixed monomer containing a (meth) acrylate having an epoxy group such as a glycidyl group and a (meth) acrylate having a carboxyl group. . The mixed monomer may contain a monomer other than the (meth) acrylate having an epoxy group and the (meth) acrylate having a carboxyl group. As such a monomer, the glass transition temperature of the obtained copolymer is −80 ° C.
There is no particular limitation as long as it falls within the range of 25 to 25 ° C. Glass transition temperature of homopolymer is -80 ° C to 0
When the temperature is in the range of 0 ° C., the above conditions are easily satisfied, and as such a monomer, an unsubstituted or substituted alkyl (meth) acrylate monomer is preferably used. Such a monomer usually has 2 to 15 carbon atoms,
Examples thereof include an alkyl acrylate monomer having 2 to 8 carbon atoms, an alkyl methacrylate monomer having 8 to 15 carbon atoms, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, and alkoxyalkyl acrylate. Specifically, C such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, 2-methylbutyl acrylate, isoamyl acrylate, and n-octyl acrylate.
_2-8 alkyl acrylate and _C8-15 alkyl methacrylate such as isooctyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate and / or n-octyl methacrylate, and phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, methoxyethyl acrylate, For example, ethoxyethyl acrylate.

The (meth) acrylate monomer having an epoxy group is not particularly limited as long as it can crosslink with the carboxyl group of the (meth) acrylate monomer having a carboxyl group, and examples thereof include glycidyl (meth) acrylate and / or alicyclic group. It may include (meth) acrylate having an epoxy group. Such (meth) acrylate monomers having an epoxy group are commercially available, for example, from Daicel Chemical Industries under the trade names of M100 and A200.

Similarly, having a carboxyl group (meta)
Acrylate monomers also include, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, glataconic acid, 2-acryloyloxyethylsuccinic acid (Kyoei Kagaku, HOA-MS), 2-acrylic acid. Loyloxyethylphthalic acid (Kyoei Chemical Co., HOA-M
PL), ω-carboxy-polycaprolactone (repeating unit (n) ≈2) monoacrylate (Toagosei, M-
5300), phthalic acid monohydroxyethyl acrylate (Toagosei, M-5400) and / or acrylic acid dimer (Toagosei, M-5600).

The above-mentioned mixed monomer is preferably 4 to 3 (meth) acrylate having an epoxy group based on the total weight.
Contains 5% by weight and has a carboxyl group (meth)
Having the above-mentioned epoxy group for acrylate (meth)
The molar ratio of acrylate is 0.15 to 4.0. As described above, the thermosetting acrylic pressure-sensitive adhesive polymer is 2 to 50.
This is because it contains mol% of epoxy groups and the molar ratio of the epoxy groups to the carboxyl groups is in the range of 0.15 to 4.0.

The above-mentioned mixed monomers can generally be radically polymerized under a polymerization initiator based on an azo compound or a peroxide. The polymerization method includes a solution polymerization method,
An emulsion polymerization method, a suspension polymerization method, a bulk polymerization method or other well-known and commonly used polymerization methods can be used. In particular, the solution polymerization method is preferable because an acrylic thermosetting pressure-sensitive adhesive layer having a thickness described below can be effectively provided on the heat resistant substrate. According to the invention, solution polymerization is usually carried out under a nitrogen atmosphere. The polymerization temperature and the polymerization time are preferably 30 to 80 ° C. and 1 to 24 hours, respectively. This is to prevent gelation of the thermosetting acrylic adhesive polymer.

The acrylic thermosetting pressure-sensitive adhesive layer is 0.1 to 1
It is desirable to have a thickness of 0 μm. When the acrylic thermosetting pressure-sensitive adhesive layer has a thickness of less than 0.1 μm, it becomes difficult to follow when it adheres to an adherend and is easily peeled off during use. On the other hand, when the thickness of the acrylic thermosetting pressure-sensitive adhesive layer exceeds about 10 μm, it becomes difficult to sufficiently reduce the adhesive force after thermosetting. Further, during use, a solvent, a chemical, or the like permeates between the pressure-sensitive adhesive film and the adherend, which easily causes peeling of the pressure-sensitive adhesive film or contamination of the adherend.

Similarly, the amount of the thermosetting acrylic pressure-sensitive adhesive polymer is not limited as long as the objects and effects of the present invention are not impaired, but such an adhesive polymer is contained in the acrylic thermosetting pressure-sensitive adhesive layer in an amount of 70% by weight or more. It is preferably included. This is because if the thermosetting acrylic pressure-sensitive adhesive polymer is contained in an amount of less than 70% by weight, the adhesive force of the pressure-sensitive adhesive film tends to be less likely to decrease. The thermosetting acrylic pressure-sensitive adhesive layer may contain a small amount of acrylic polymer in addition to the thermosetting acrylic pressure-sensitive adhesive polymer.

Next, a method for manufacturing the above-mentioned pressure-sensitive adhesive film will be described. First, the thermosetting acrylic pressure-sensitive adhesive polymer prepared as described above is dissolved in an organic solvent to prepare a coating solution. As the organic solvent, ethyl acetate, methyl ethyl ketone (MEK), toluene or a mixture thereof can be usually used. Next, the heat-resistant substrate is uniformly coated with the coating solution by die coating, knife coating, bar coating or any other well-known and commonly used coating method. Since most of the above-mentioned thermosetting acrylic adhesive polymer is used as the coating solution, uniform application can be easily realized. Then, the coating solution is dried together with the heat resistant substrate to remove the solvent to obtain an adhesive film.

The above-mentioned pressure-sensitive adhesive film of the present invention can be used as a mask for an adherend such as an electric circuit board, as described below. First, the pressure-sensitive adhesive film of the present invention is a substrate for electric circuits (hereinafter,
Also simply referred to as a "substrate". ) Attach it to the specified position.
Preferably, the pressure-sensitive adhesive film is attached to the electric circuit substrate while being heated to 80 to 120 ° C. This is because the adhesive film sufficiently adheres to the electric circuit board. Next,
The electric circuit substrate is etched at 100 ° C. or lower to provide an electric circuit on the substrate. At this time, the portion of the electric circuit board covered with the adhesive film is protected by the adhesive film with a high adhesive force, and the penetration of the etching chemical liquid into the adhesive surface can be prevented. Then, the electric circuit board is washed with hot water or an organic solvent. Also at this time, the pressure-sensitive adhesive film effectively prevents its penetration into the pressure-sensitive adhesive surface due to its heat resistance and solvent resistance.
Next, after sealing the electric circuit on the substrate with an epoxy resin, the epoxy resin is cured by heating at 150 to 250 ° C. At that time, since the pressure-sensitive adhesive film is also heated, the pressure-sensitive adhesive film loses most of its tackiness due to the curing of the thermosetting acrylic pressure-sensitive adhesive polymer. That is, according to the present invention, the adhesive film loses its adhesiveness by mere heating regardless of whether or not the base material of the adhesive film and the adherend have light transmittance. Therefore,
The base material and adherend of the pressure-sensitive adhesive film can be widely selected. Further, as described above, the thermosetting acrylic pressure-sensitive adhesive polymer occupies most of the acrylic thermosetting pressure-sensitive adhesive layer, and the thickness of the pressure-sensitive adhesive layer is thin, and unreacted monomers are less likely to remain. Almost unlikely to occur.
As a result, the pressure-sensitive adhesive film can be easily peeled off again without leaving any adhesive residue on the substrate.

The pressure-sensitive adhesive film of the present invention is also effectively used to protect the other surface of a substrate such as a metal foil or a metal plate having an electric circuit on one surface from etching.

Although the present invention has been described above in accordance with the preferred embodiment, the present invention is not limited to this.

As long as the objects and effects of the present invention are not impaired, the above-mentioned unsubstituted or substituted alkyl (meth) acrylate monomer having a glass transition temperature of -80 to 0 ° C. and a thermosetting acrylic pressure-sensitive adhesive polymer, and A copolymerizable monomer other than an acrylate monomer having an epoxy group such as a glycidyl group and / or a carboxyl group may be copolymerized. An example of such a copolymerizable monomer is a (meth) acrylate monomer having a homopolymer glass transition temperature of 0 ° C. or higher, specifically, methyl (meth) acrylate, ethyl methacrylate, n-butyl (meth) acrylate, Alkyl (meth) acrylates such as isobornyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate Hydroxyalkyl (meth) acrylate, acrylamide, dimethylaminoethyl (meth) acrylate, N-vinylpyrrolidone, 2-hydroxy-3-phenoxypropyl acrylate, dimethylaminopropyl Ropyracrylamide, N,
It is a polar monomer such as N-dimethyl acrylamide, isopropyl acrylamide, and N-methylol acrylamide.

Further, the acrylic thermosetting adhesive layer does not need to contain a single thermosetting acrylic adhesive polymer, but a thermosetting acrylic mixed adhesive polymer containing a plurality of adhesive polymers shown below ( Mixed adhesive polymer). (1) A first acrylic adhesive polymer derived from a monomer containing a (meth) acrylate monomer having a glycidyl group (2) A second acrylic adhesive polymer derived from a monomer containing a (meth) acrylate monomer having a carboxyl group Unlike a single thermosetting acrylic adhesive polymer, such a mixed adhesive polymer is polymerized separately for each adhesive polymer and can be stored until just before coating. Therefore, compared with a single thermosetting acrylic adhesive polymer, the mixed adhesive polymer is less likely to gel during polymerization and the life of the coating solution is longer.

The first adhesive polymer and the second adhesive polymer constituting the mixed adhesive polymer are used to ensure the adhesiveness of the adhesive layer, as in the case of the above-mentioned single thermosetting acrylic adhesive polymer. , Respectively, generally at -80 ° C to 2
It has a glass transition temperature of 5 ° C. Also, for the same reason as in the case of a single thermosetting acrylic adhesive polymer,
The first adhesive polymer and the second adhesive polymer each have a weight average molecular weight of 10,000 to 1,000,000. Further, the monomers constituting the mixed adhesive polymer and the proportion thereof are also the same as in the case of the single thermosetting acrylic adhesive polymer, and further, the acrylic thermosetting adhesive layer,
It contains similar amounts of mixed adhesive polymers as in the case of a single thermosetting acrylic adhesive polymer.

Further, the acrylic thermosetting adhesive layer contains
A cross-linking agent that cross-links the carboxyl groups may be added, preferably in an amount of less than 3% by weight. According to the present invention, it is desirable that such a cross-linking agent cross-links carboxyl groups at 100 ° C or lower. This is because the acrylic thermosetting pressure-sensitive adhesive layer has high cohesive force and heat resistance before thermosetting. Preferred crosslinking agents are isocyanate-based crosslinking agents such as those sold under the trade name of Colonate L from Nippon Polyurethane, those sold under the trade name of Chemitite PZ-33 from Nippon Shokubai, or bisamide (isophthaloylbis-2- Methylaziridine) or an aziridine-based cross-linking agent, or a polyfunctional epoxy resin cross-linking agent marketed by Soken Chemical Industry under the trade name of E-AX, commercially available from Soken Chemical Industry under the trade name of M-5A. It is a metal chelate-based cross-linking agent. Dry the thermosetting acrylic adhesive polymer coating solution together with the heat-resistant base material,
This is because the crosslinking can be efficiently performed in the step of removing the solvent. Further, the crosslinking agent is more preferably added to the acrylic thermosetting pressure-sensitive adhesive layer in an amount of less than 3% by weight. On the other hand, if the cross-linking agent is contained in an amount of 3% by weight or more,
The acrylic thermosetting pressure-sensitive adhesive layer tends to lose its tackiness.

When the adhesiveness (anchoring property) between the heat-resistant base material and the acrylic thermosetting pressure-sensitive adhesive layer is poor, when the pressure-sensitive adhesive film is peeled from the adherend, The acrylic thermosetting pressure-sensitive adhesive layer may peel off between the layers. In such a case, one surface of the heat resistant substrate may be subjected to a surface treatment for easy adhesion by a well-known and commonly used technique in order to improve the anchoring property with the acrylic thermosetting pressure-sensitive adhesive layer. A preferred example of such surface treatment is a physical treatment method such as corona discharge treatment, flame treatment, plasma treatment or ultraviolet irradiation treatment, or a wet chemical treatment method. In particular, corona treatment is more preferable. This is because the heat-resistant base material subjected to corona treatment is commercially available and easily available.

Further, the above surface treatment is difficult,
When the anchoring property is insufficient even after the surface treatment, a primer treatment may be performed to further improve the anchoring property. Primer treatment is a process of forming a coating layer (primer layer) on the heat-resistant base material that has excellent adhesion to both the heat-resistant base material and the acrylic thermosetting adhesive layer, and then applying the acrylic-based coating on the primer layer. This is to provide a thermosetting adhesive layer. At that time, the thickness of the primer layer is 0.1 to 2 μ.
In m, the total thickness of the acrylic thermosetting pressure-sensitive adhesive layer and the primer layer is preferably 0.2 to 10 μm.
If the thickness of the primer layer is 0.1 μm or less, no effect can be expected, and if it is 2 μm or more, solvent or chemical may soak into the primer layer, which may cause peeling of the adhesive film or contamination of the adherend. Is. Further, the other surface of the heat resistant substrate may be subjected to a peeling treatment. When the other surface is subjected to a release treatment, the heat-peelable thermosetting pressure-sensitive adhesive film of the present invention can be stored as a rolled tape. As a release agent for performing the release treatment, a silicone-based release agent is used. A fluorine-based release agent, a (meth) acrylic release agent having a long chain alkyl group, and a vinyl ether release agent having a long chain alkyl group can be used.

Further, antioxidants, ultraviolet absorbers, fillers (for example, inorganic fillers, conductive particles or pigments, etc.), lubricants such as waxes, tackifiers, plasticizers, etc., as long as the objects and effects of the present invention are not impaired. An additive such as a curing accelerator or a fluorescent dye may be included in the acrylic thermosetting pressure-sensitive adhesive layer.

[0033]

EXAMPLES Next, the present invention will be explained according to examples. However, it will be easily understood by those skilled in the art that the present invention is not limited to these. Examples 1-3 and Comparative Examples 1-2 1. Preparation of Acrylic Adhesive Polymer As shown in the left column of Table 1, acrylic acid butyl ester, that is, butyl acrylate (Mitsubishi Chemical Industries), acrylic acid (Wako Pure Chemical Industries, JIS (Japanese Industrial Standards) special grade), glycidyl methacrylate (NOF Corporation). , Trade name Nissan Bremmer G), phenoxyethyl acrylate (Osaka Organic Chemical Industry, trade name Biscoat # 192), 2-hydroxy-3-phenoxypropyl acrylate (M-570).
0, Toa Gosei Co., Ltd.) was mixed at a predetermined composition ratio to prepare a monomer mixture. Next, after the monomer mixture was put into a solvent, a polymerization initiator (Wako Pure Chemical Industries, JIS special grade) consisting of 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name, V-65) was used as a monomer. 0.2% by weight is further added to the above and polymerized in a nitrogen atmosphere at 50 ° C. for 24 hours,
An acrylic copolymer having a solid content of 30% by weight, that is, an acrylic adhesive polymer solution was prepared. Here, as shown in the right column of Table 1, the solvent was used by changing according to the monomer mixture. That is, with respect to the monomer mixtures of Examples 1 to 3, ethyl acetate and methyl ethyl ketone, which are commercially available from Wako Pure Chemical Industries, at a quality level of JIS special grade, in a weight ratio of 4:
A mixed solvent containing 1 was prepared and used, and the above ethyl acetate solvent was used for the monomer mixtures of Comparative Example 1 and Comparative Example 2.

[0034]

[Table 1] Footnote BA: Butyl acrylate, GMA: Glycidyl metallate, AA: Acrylic acid, MEK: Methyl ethyl ketone, PEA: Phenoxyethyl acrylate, M-5700: 2-
Hydroxy-3-phenoxypropyl acrylate

2. Preparation of heat-peelable thermosetting pressure-sensitive adhesive film Next, a thermosetting pressure-sensitive adhesive film was prepared as follows using the above acrylic pressure-sensitive adhesive polymer. First, each of the above acrylic adhesive polymers was diluted with a mixed solvent of methyl ethyl ketone (MEK) and toluene (the mixing ratio was 55:45 by weight), and the solid content was 5% by weight and 1% by weight.
A 0 wt% coating solution was prepared. The coating solution is a polyphenylene sulfide substrate film (Toray, Torelina, thickness 12 μm, single-sided corona treatment)
After applying by knife coating to the corona-treated surface of
It was put in an oven at 00 ° C. for 10 minutes and dried to remove the mixed solvent, thereby forming an acrylic thermosetting pressure-sensitive adhesive layer. Next, the above-mentioned acrylic thermosetting pressure-sensitive adhesive layer was measured to determine its thickness. When a coating solution of 10% solid content is used, the thickness of the acrylic thermosetting adhesive layer is about 5μ.
It was m. When the coating solution with a solid content of 5% was used, the thickness of the acrylic thermosetting pressure-sensitive adhesive layer was about 1 μm.

A release film of polyethylene terephthalate (Teijin DuPont, Purex A31, thickness 38 μm) release-treated with silicone was further laminated on the acrylic thermosetting adhesive layer to prepare an evaluation sample to be described later. Prepared for production.

3. Preparation of Evaluation Sample and Measurement of Adhesive Force Next, using the above-mentioned heat-peelable thermosetting pressure-sensitive adhesive film, an evaluation sample was prepared and the adhesive force was measured as follows.

First, after removing the release film, the acrylic thermosetting pressure-sensitive adhesive layer was applied at a heating temperature of 80 ° C. for 2 m / min.
At a line speed of about 1.5-2 kg / cm and a hot-rolled copper foil made of Japanese foil having a thickness of 35 μm was thermally laminated to obtain an evaluation sample. The evaluation sample was left at room temperature (atmosphere of about 25 ° C.) for 24 hours or more, and then the acrylic thermosetting pressure-sensitive adhesive layer was peeled off together with the film base material at a speed of 25 ° C. and 300 mm / min while peeling at 180 °. The adhesive strength (initial adhesive strength) was determined. Further, the adhesion of 180 ° peel (adhesion after heat curing) of the evaluation sample was obtained even after the acrylic thermosetting pressure-sensitive adhesive layer was thermally cured. Thermal curing was performed as follows. That is, the acrylic thermosetting pressure-sensitive adhesive layer is sandwiched between two stainless 304 plates (JIS BA material) having a thickness of 2 mm via a base film and a hard rolled copper foil, and then 60 kg / cm ² While applying the surface pressure of
Heat for 0 minutes. Then, the 180 ° peel adhesive strength of the evaluation sample was measured after leaving the evaluation sample at room temperature (about 25 ° C.) for 1 hour or more after the heat curing. In addition, at the time of measurement, the presence or absence of adhesive residue on the copper foil was visually observed.

Example 4 In this example, as shown in Table 2, the coating solution used in Example 1 was added with an aziridine crosslinking agent (isophthaloylbis-2-methylaziridine) in a solid content ratio of 0.2. A heat-peelable thermosetting pressure-sensitive adhesive film was obtained in the same manner as in Example 1 except that the amount was added in an amount of wt%, and an evaluation sample was prepared and evaluated.

Examples 5 to 7 In this example, the composition shown in Table 2 was used to obtain a heat-peelable thermosetting adhesive film in the same manner as in Example 1 above, and an evaluation sample was prepared and evaluated. However, in Examples 6 and 7, the polymerization temperature was set to 55 ° C., and an adhesive polymer solution having a solid content of 35% was obtained. Also, bar coating was performed at a thickness of about 1 μm on a PPS film having a thickness of 16 μm instead of the polyphenylene sulfide (PPS) film having a thickness of 12 μm. In the table, MAA is methacrylic acid (Wako Pure Chemical Industries, JIS (Japanese Industrial Standard) special grade), and M
-5300 is ω-carboxy-polycaprolactone (repeating unit (n) ≈2) monoacrylate (Toa Gosei)
And the other monomers are the same as those used in the other examples above.

Comparative Example 3 In this example, as shown in Table 2, the coating solution used in Comparative Example 2 was added with an aziridine crosslinking agent (isophthaloylbis-2-methylaziridine) in a solid content ratio of 0.2. A heat-peelable thermosetting pressure-sensitive adhesive film was obtained in the same manner as in Example 1 except that the amount was added in an amount of wt%, and an evaluation sample was prepared and evaluated.

[0042]

[Table 2]

Table 3 shows the initial adhesive strength of the pressure-sensitive adhesive films in Examples 1 to 7 and Comparative Examples 1 to 3 and the adhesive strength after heat curing and the presence or absence of adhesive residue. According to this Table 3, it can be seen that the pressure-sensitive adhesive films of Comparative Examples 1 and 2 have adhesive residue after heat curing. Comparative Example 3 has a cohesive force,
A crosslinking agent was added to improve heat resistance. as a result,
Compared with Comparative Example 2 before heat curing, the thickness of the adhesive was 1 μm.
Even with m, no adhesive residue was produced. But,
After the heat curing, the adhesive remained and the adhesive strength was high as in Comparative Examples 1 and 2. On the other hand, it can be seen that the pressure-sensitive adhesive films of Examples 1 to 7 had a sufficiently high initial adhesive force and could be peeled off with very low adhesive force without adhesive residue after heat curing. Therefore, the heat-peelable pressure-sensitive adhesive film (heat-reactive masking tape) of the present invention exhibits high adhesive strength after being adhered to an adherend, and the heat-curing step results in low adhesion and easy peeling without adhesive residue. It became clear that it can be done.

[0044]

[Table 3] Footnote: All units of adhesive force in the table are N / 50 mm. Also,
“Contamination” indicates adhesive residue on the adherend.

Example 8 The heat of an acrylic thermosetting pressure-sensitive adhesive layer having the composition of Example 3 and having a thickness of about 1 μm when cured at 120 ° C. and 150 ° C. under the thermal curing conditions. The adhesive strength after curing was measured. Thermal curing was performed as follows. That is, the acrylic thermosetting pressure-sensitive adhesive layer is sandwiched between two stainless 304 plates (JIS BA material) having a thickness of 2 mm via a base film and a hard rolled copper foil, and then 60 kg / cm ² 60 at 120 ℃ while applying the surface pressure of
Min, 120 minutes, 150 ° C., 30, 60, 120 minutes. Then, the adhesive strength of the 180 ° peel of the evaluation sample was as follows:
(° C) and left for measurement.

[0046]

[Table 4]

From Table 4, the above-mentioned thermosetting pressure-sensitive adhesive film still retains a high adhesive force when cured by heat at 120 ° C.
It can be seen that the heat curing at 50 ° C. or higher enables peeling with very low adhesive strength. Therefore, the thermosetting adhesive film (thermoactive masking tape) of the present invention
After being attached to an adherend, the adhesive has low adhesion by a heat curing step at 150 ° C. or higher, and can be easily peeled off.

[0048]

EFFECTS OF THE INVENTION The pressure-sensitive adhesive film according to the present invention exhibits releasability when heated, and does not cause damage to the adherend and peeling of the adhesive on the adherend during peeling. Further, since light such as ultraviolet rays is not necessary for exhibiting the peeling property, a material that is opaque to light can be used as the base material of the adhesive film.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Emi Ishii             Sumitomo 3-8-8 Minami-Hashimoto, Sagamihara City, Kanagawa Prefecture             Within 3M Co., Ltd. (72) Inventor Takanobu Yorinobu             Sumitomo 3-8-8 Minami-Hashimoto, Sagamihara City, Kanagawa Prefecture             Within 3M Co., Ltd. F-term (reference) 4J004 AA10 AB04 CA06 CB03                 4J040 DF041 DF051 GA07 GA11                       JA09 JB02 JB09 LA08

Claims (8)

[Claims] 1. A heat-peelable thermosetting pressure-sensitive adhesive film comprising a heat-resistant base material and an acrylic thermosetting pressure-sensitive adhesive layer provided on at least one surface of the base material. A heat-peelable thermosetting adhesive film in which the curable adhesive layer contains a thermosetting acrylic adhesive polymer having an epoxy group and a carboxyl group in the molecule. 2. The heat-peelable thermosetting adhesive film according to claim 1, wherein the thermosetting acrylic adhesive polymer has a glass transition temperature of −80 to 25 ° C. 3. The thermosetting acrylic pressure-sensitive adhesive polymer contains 4 to 35% by weight of the epoxy group-containing monomer, and the molar ratio of the epoxy group to the carboxyl group is 0.15 to 4.0. The heat-peelable thermosetting pressure-sensitive adhesive film according to claim 1 or 2. 4. The thermosetting acrylic pressure-sensitive adhesive polymer is a copolymer derived from a mixed monomer containing an epoxy group-containing (meth) acrylate and a carboxyl group-containing (meth) acrylate. The heat-peelable thermosetting pressure-sensitive adhesive film according to any one of 3 above. 5. The heat-peelable thermosetting adhesive film according to claim 3, wherein the mixed monomer further contains (meth) acrylate having an alkyl group having 2 to 15 carbon atoms. 6. The acrylic thermosetting pressure-sensitive adhesive layer has a thickness of 0.1.
The heat-peelable thermosetting adhesive film according to any one of claims 1 to 5, which has a thickness of 1 to 10 µm. 7. The heat resistant substrate contains a heat resistant material selected from at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide and polyimide. The heat-peelable thermosetting pressure-sensitive adhesive film according to. 8. The heat-peelable curable pressure-sensitive adhesive film according to claim 1, wherein the heat-resistant base material has a thickness of 1 to 200 μm.