JPH07145357A - Heat release sheet and release method - Google Patents

Abstract

(57) [Abstract] [Purpose] A bonding means that does not require re-bonding due to cooling and solidification and can easily dissolve the bonded state without adhesive residue at any time and does not require cleaning treatment of the adherend after separation. To get. A heat-peelable sheet having a pressure-sensitive adhesive layer (2) containing a foaming agent that expands and / or expands by heating on one or both sides of a base material (1) that is induction-heated with high frequency, and induction with high frequency. A pressure-sensitive adhesive layer containing a foaming agent adhered to an adherend to be heated is foamed and / or expanded under induction heating of the adherend.
Alternatively, a peeling method of separating from the adherend after the expansion treatment. [Effect] The foaming process can be performed in a short time by induction heating, and the separation work can be performed at any time after heating without damaging the adherend.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat release sheet and a release method capable of releasing the adhesive state by reducing or losing the adhesive force of a pressure sensitive adhesive layer at any time by an induction heating method.

[0002]

2. Description of the Related Art From the standpoint of labor saving and automation of the process by reusing resources and achieving easy separation after processing of a workpiece temporarily fixed and fixed during processing such as polishing and cutting,
There is a demand for a bonding means that can easily release the bonded state.

Conventionally, as an adhesive means applicable to such a purpose, a hot melt adhesive made of a thermoplastic resin containing magnetic powder is known. (JP-A-4-93
No. 381). This adhesive is melted by induction heating based on the contained magnetic powder so that the adhesive state of the adherend and the like can be easily released by the decrease in the adhesive force.

However, since the separation of the adhesive state by the hot melt adhesive is the destruction of the agglomerated state by the melting and softening of the adhesive, the debris of the hot melt adhesive remains on the adherend. (Adhesive residue), there is a problem that it needs to be removed by washing,
In addition, there is a problem that it is necessary to release the bonding state immediately after the heat treatment so that the hot melt adhesive does not solidify by cooling and re-bonding.

[0005]

DISCLOSURE OF THE INVENTION The present invention can easily remove the adhesive state without adhesive residue at any time without causing problems such as re-adhesion due to cooling and solidification, and therefore, the adherend is washed after separation. The problem is to develop a bonding means that does not need to be applied.

[0006]

The present invention is characterized in that a pressure-sensitive adhesive layer containing a foaming agent that expands and / or expands by heating is provided on one or both sides of a base material that is induction-heated with high frequency. The heat-release sheet and the pressure-sensitive adhesive layer containing a foaming agent adhered to an adherend that is induction heated at high frequency are foamed and / or expanded under the induction heating of the adherend, and then separated from the adherend. The present invention provides a peeling method characterized by:

[0007]

By including a foaming agent in the pressure-sensitive adhesive layer and heating the pressure-sensitive adhesive layer through induction heating of the substrate or the adherend by high frequency, the foaming agent contained expands and / or expands. The adhesive force of the pressure-sensitive adhesive layer is reduced or lost, whereby the adherend and the pressure-sensitive adhesive layer can be easily separated. Further, in that case, the adhesive force of the pressure-sensitive adhesive layer is not restored, and the cooling rather acts to reduce the adhesive force, so that the separating operation can be performed at any time without any time constraint. Furthermore, the decrease in adhesive strength due to foaming and / or expansion of the pressure-sensitive adhesive layer is due to the decrease in the adhesive area, and since the pressure-sensitive adhesive layer maintains its integrity, adhesive residue is less likely to occur during separation. It is possible to omit washing of the adherend.

[0008]

EXAMPLE A heat-peelable sheet of the present invention is formed by foaming and / or foaming by heating on one or both sides of a base material that is induction-heated by high frequency
Alternatively, it has a pressure-sensitive adhesive layer containing an expanding foaming agent. Examples thereof are shown in FIGS. 1 and 2. 1 is the base material, 2,
3 is a pressure sensitive adhesive layer.

Examples of the base material which is induction-heated by high frequency include iron, nickel, copper, aluminum, titanium, zinc,
Use of various conductors or magnetic materials such as tin as a main component, stainless steel such as SUS340, alloys such as permalloy, metal oxides such as ferrite, amorphous alloys such as iron and cobalt. be able to.

The substrate is usually 1 to 500 μm thick, especially 3 to
It is made of a sheet-like material having a thickness of 100 μm, but in that case, a form including a conductor or a magnetic substance is arbitrary. By the way, as its form, a single-layer form made of foil, a laminate form having a conductor layer or a magnetic layer made of a foil, a vapor deposition film or the like in the base layer, a contained form in which conductive powder or magnetic powder is dispersed in the base layer, Examples thereof include a superposed form in which a layer containing conductive powder or magnetic powder dispersed therein is applied to the base layer, and a form in which the conductive powder or the like is replaced with a fibrous material. Two or more kinds of magnetic materials or conductive materials may be used, or they may be used in combination. The base material is
It can be used in an appropriate form as a core material or a support material of a pressure-sensitive adhesive layer having a net shape, a porous shape, a non-woven shape, or the like.

The base layer may be, for example, a processed fiber product such as paper, cloth, or non-woven fabric, a plastic or rubber-like polymer film or foamed film, or a plastic laminate or a laminate of these plastics. An appropriate thin sheet that can serve as a supporting base material such as a pressure-sensitive adhesive layer may be used.

The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer includes a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a styrene / conjugated diene block copolymer-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. An appropriate adhesive or the like can be used, and an ultraviolet curable adhesive or the like can also be used (JP-A-56).
No. 61468, JP 61-174857, and JP 63-17981).

[0013] Further, those which contain a heat-melting resin having a melting point of about 200 ° C or less to improve the creep property, and those which have a low adhesive strength at room temperature and exhibit sufficient adhesive strength by heating. A pressure sensitive adhesive or the like can also be used (Japanese Patent Publication No. 56-
13040, Japanese Patent Publication No. 2-50146, and Japanese Patent Laid-Open No. 56-13040). The pressure-sensitive adhesive may be a mixture of appropriate additives such as a cross-linking agent, a tackifier, a plasticizer, a filler and an anti-aging agent, if necessary.

More specifically, for example, a rubber-based pressure-sensitive adhesive containing natural rubber or various synthetic rubbers as a base polymer, methyl group, ethyl group, propyl group, butyl group, 2-ethylhexyl group, isooctyl group, isononyl. Group, isodecyl group, dodecyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, usually acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms Acrylic acid-based alkyl ester such as, hydroxyethyl group, hydroxypropyl group, ester such as acrylic acid or methacrylic acid having a functional group-containing group such as glycidyl group, acrylic acid, methacrylic acid, itaconic acid,
Acrylic pressure-sensitive adhesives based on acrylic polymers containing N-methylolacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, etc.

The pressure-sensitive adhesive is appropriately selected and used according to the purpose of use such as the adhesive strength to an adherend, and the pressure-sensitive adhesive layer that foams and / or expands by heating has a foaming agent added to the pressure-sensitive adhesive. Can be formed by blending.

As the foaming agent, various kinds of foaming agents that can achieve the above objects can be used. Therefore, for example, when a heat-sensitive pressure-sensitive adhesive is used, a foaming agent that foams and / or expands at a temperature higher than the bonding treatment temperature of the adhesive is used. Examples of foaming agents that can be used include decomposition-type inorganic foaming agents such as ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and azides.

An organic foaming agent such as an azo compound may also be used. Examples thereof include fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azo compounds such as azobisisobutyronitrile and azodicarbonamide, barium azodicarboxylate, paratoluenesulfonyl hydrazide and diphenyl sulfone-. 3,3'-disulfonyl hydrazide, 4,4'-
Hydrazine compounds such as oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide), ρ-toluylenesulfonyl semicarbazide and 4,
Semicarbazide compounds such as 4'-oxybis (benzenesulfonyl semicarbazide), 5-morpholyl-
Triazole compounds such as 1,2,3,4-thiatriazole, N-nitroso compounds such as N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide , Other low boiling point compounds, and the like.

Further, in the present invention, as a foaming agent, for example, a suitable substance such as isobutane, propane, and pentane, which is easily gasified and exhibits thermal expansion properties, is included in the shell-forming substance by a coacervation method, an interfacial polymerization method, or the like. Heat-expandable fine particles can also be used. The average particle diameter of the heat-expandable fine particles used is generally 1 to 50 μm.

As the shell-forming substance forming the heat-expandable fine particles, for example, vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc. are generally used. In the present invention, it may be made of a heat-meltable substance or a substance that is destroyed by thermal expansion.

The content ratio of the foaming agent in the pressure-sensitive adhesive layer is
Although it is appropriately determined depending on the degree of reduction in the adhesive strength, etc., it is generally 10% by weight or more, preferably 15 to 95% by weight, particularly 20 to 80% by weight. The expansion ratio of the pressure-sensitive adhesive layer is appropriately determined depending on the surface shape, material, etc. of the adherend, but it is generally preferable to design the expansion ratio to be about 1.5 to 100 times.

The pressure-sensitive adhesive layer containing a foaming agent is formed according to a conventional method for forming an adhesive tape, such as a coating method on a base material or a transfer method of a material formed on a separator but transferred to a base material. It can be carried out. The pressure-sensitive adhesive layer may be provided in a solid shape, or may be partially applied in a dot shape or a line shape by pattern coating by, for example, a gravure printing method or a screen printing method. The thickness of the pressure-sensitive adhesive layer is appropriately determined depending on the surface shape and material of the adherend, but generally 1 to 5
The thickness is 00 μm, especially 5 to 100 μm.

In the present invention, as illustrated in FIG. 2, the pressure-sensitive adhesive layer may be formed as a superposed layer of a layer 31 containing a foaming agent and capable of thermal expansion and a layer 32 containing no foaming agent. The pressure-sensitive adhesive layer 3 in the overlapping form has an advantage that the adhesive strength of the layer containing no foaming agent to be adhered to the adherend can be easily controlled.

The foaming agent-containing layer in the pressure-sensitive adhesive layer in the overlapping form may be formed according to the above-mentioned foaming agent-containing pressure-sensitive adhesive layer, or may be formed as a mixed layer of the foaming agent and the binder. Good. As the binder, a generally known polymer such as a rubber-based or resin-based polymer that allows foaming and / or expansion of the foaming agent, preferably one that does not restrain foaming and / or expansion of the foaming agent as much as possible. To be

The mixed layer of the foaming agent and the binder is formed by heating and foaming the surface of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer adhered to the adherend is peeled from the adherend at any time. The volume is changed to reduce the area of adhesion to the adherend, so that it can be easily peeled from the adherend. Such a mixed layer can be formed by using a binder instead of the pressure-sensitive adhesive, and the thickness, the content ratio of the foaming agent and the like can be similar to those of the foaming agent-containing pressure-sensitive adhesive layer described above.

The layer containing no foaming agent in the pressure-sensitive adhesive layer in the superposed form can be formed by using a pressure-sensitive adhesive containing no foaming agent in the same manner as the above-mentioned pressure-sensitive adhesive layer containing a foaming agent. The thickness of the layer containing no foaming agent is preferably as thin as possible from the point of improving the releasability by making the distance between the adherend and the foaming agent-containing layer as close as possible. Considering adhesion, etc., about 0.1-50 μm, especially 0.5
˜5 μm is preferred.

The heat release sheet of the present invention can be firmly adhered to an adherend at the time of adhesion, and when it is desired to release the adhered state, as shown in FIG. 3, the pressure sensitive adhesive layer of the substrate 1 is subjected to induction heating by high frequency. It can be easily peeled off or separated from the adherend 4 by the heat foaming treatment 21 for foaming and / or expanding the foaming agent therein. Such a heat release sheet has an advantage that it can be used for an adherend having poor heat resistance.

On the other hand, in the peeling method of the present invention, when the adherend can be induction-heated with a high frequency such as a conductor or a magnetic substance, a foaming agent containing a pressure-sensitive adhesive layer in the above heat-peelable sheet is contained. A heat-foaming treatment for forming a predetermined adhered state of an adherend or the like through a pressure-sensitive adhesive layer and then foaming and / or expanding the foaming agent in the pressure-sensitive adhesive layer under induction heating of the adherend with high frequency. It can be easily peeled off or separated from the adherend. Therefore, in this case, the pressure-sensitive adhesive layer containing a foaming agent can be applied as a coating type adhesive, or as an adhesive sheet attached to a supporting substrate made of an appropriate thin film such as a plastic film. In that case, it can be applied as a double-sided adhesive sheet or the like.

The heat release sheet or the release method of the present invention is preferably used or used in such a manner that the adherends are adhered for a predetermined period of time and then the adhesion state is released after the adhesion purpose is achieved. is there. Incidentally, examples thereof include formation of an adhesive composite for recycling two or more articles, for example, an article made of a polymer and an article made of metal, fiber, paper, or the like, various electric devices or electronic devices, and display devices. Carrier tapes for transportation and temporary fixing of parts in the assembly process such as etc., temporary fixing materials or fixing materials, surface protection materials and masking materials for preventing contamination damage of metal plates, plastic plates, glass plates, etc., semiconductors It can be used as a temporary fixing material or a fixing material when polishing or cutting a wafer.

Example 1 50 parts of ethyl acrylate (parts by weight, the same applies hereinafter), 50 parts of butyl acrylate and 2-hydroxyethyl acrylate 1
100 parts of a base polymer consisting of 1 part of a copolymer (weight average molecular weight of about 600,000), 5 parts of a polyurethane cross-linking agent, and heat-expandable fine particles (average particle size 15 μm, specific gravity 1.01) 3
Toluene solution containing 0 parts added and mixed is coated on a separator and dried to form a pressure-sensitive adhesive layer having a thickness of 50 μm. Using the 20 mm square pressure-sensitive adhesive layer, two aluminum plates (thickness 1 mm, A shear test piece is formed by adhering a width of 25 mm and a length of 100 mm, and the adhering portion is an induction heating device (output 6).
Induction heating was performed at 00 W and a frequency of 45 kHz for 5 seconds to heat-foam. In the above, the shear adhesive strength of the test piece before and after induction heating was examined (pulling speed 50 mm /
Minutes). The results are shown in Table 1.

Example 2 The pressure-sensitive adhesive layer on the separator obtained in Example 1 was 50 μm thick.
It was transferred to both sides of an aluminum foil of m and laminated to obtain a heat release sheet. Next, using the 20 mm square heat release sheet, two ABSs (thickness 3 mm, width 25 mm, length 1
00 mm) was adhered to form a shear test piece, and the bonded portion was subjected to heat-foaming treatment according to Example 1, and the shear adhesive strength of the test piece was examined. The results are shown in Table 1.

[0031]

[Table 1]

Shear test pieces were formed in accordance with Examples 1 and 2 and subjected to a heat-foaming treatment, and then an aluminum plate or ABS.
After peeling and separating one of the plates, the pressure-sensitive adhesive layer after heat treatment was peeled off from the other one, and each of the two obtained aluminum plates or ABS plates was visually observed. No adhesive residue (pressure-sensitive adhesive layer piece) was observed.

[0033]

According to the present invention, the foaming treatment can be performed in a short time by induction heating, and the adhesion state via the pressure-sensitive adhesive layer can be easily released without damaging the adherend, and the separation work can be performed. It can be performed at any time after heating, and adhesive residue can be prevented during separation, so that washing of the adherend can be omitted.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is an explanatory view of a heating and foaming treatment state.

[Explanation of symbols]

 1: Substrate 2, 3: Pressure-sensitive adhesive layer 21: Heat-foaming treatment state 31: Layer containing a foaming agent 32: Layer not containing a foaming agent 4: Adherend

Claims (3)

[Claims] 1. A heat-peelable sheet having a pressure-sensitive adhesive layer containing a foaming agent that expands and / or expands by heating, on one or both sides of a base material that is induction-heated with high frequency. 2. The heat release sheet according to claim 1, wherein the substrate has a conductor layer or a magnetic layer, and / or contains a conductive powder or a magnetic powder. 3. A pressure-sensitive adhesive layer containing a foaming agent, which adheres to an adherend that is induction heated at high frequency, is foamed and / or expanded under induction heating of the adherend, and then separated from the adherend. A peeling method characterized by the above.