JPH08188756A - Peelable liner and adhesive double coated tape or sheet - Google Patents

Abstract

PURPOSE: To provide a peelable liner for an adhesive double coated tape or sheet capable of readily peeling and exposing a beautiful inside base material even generated of a damage, deformation or dirt in the base material of the surface layer by adhering at least two layers of base materials. CONSTITUTION: At least two layers of base materials 11a and 11b are adhered through an adhesive layer 2 lowering adhesiveness by heating to obtain the objective product. Preferably, paper, a metal foil or a resin film, etc., may be used as the base material having 30-100μm thickness. The adhesive layer preferably has 10-30μm thickness, >=0.8N/20mm adhesive strength and exhibits peelable property by heating at 100-200 deg.C. Furthermore, the adhesive layer is obtained by, e.g. containing a foaming agent in a base polymer such as an acrylic copolymer composed of butyl acrylate, acrylic acid and acrylonitrile. As the foaming agent, a thermally expansive granule obtained by microcapsulizing a gasifiable component such as butane is preferable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided pressure-sensitive adhesive tape or sheet used for attaching parts to a flexible circuit board, and a release liner used for the same, and more specifically, processes such as solder reflow, punching and washing. The present invention relates to a double-sided pressure-sensitive adhesive tape or sheet and a release liner capable of suppressing damage, deformation, contamination, etc.

[0002]

2. Description of the Related Art For example, a flexible circuit board (hereinafter referred to as
Double-sided adhesive tape or sheet (hereinafter collectively referred to as double-sided tape) is used for fixing FPCs) to equipment, attaching blankets to FPCs, or making parts such as calculators, copiers, televisions, and automobiles. It is used a lot.
This double-sided tape usually has a structure in which release liners are provided on both sides of the adhesive layer.

When parts such as a blanket, an IC, and a connector are attached to an FPC using a double-sided tape, one release liner of the double-sided tape is peeled off, and the exposed pressure-sensitive adhesive layer is attached to the FPC. The parts are fixed in place by solder reflow, and then the FPC
Is washed, and then the other release liner of the double-sided tape is peeled off to fix the remaining blanket to the exposed adhesive layer.

FIG. 4 is a schematic sectional view showing an example of a conventionally known release liner used for the double-sided tape.
The release liner shown in the figure has a structure in which a release treatment layer 2 is formed on a substrate 1 made of paper, nonwoven fabric, or the like.

[0005]

As described above, in the double-sided tape using the release liner whose base material is paper or the like, the release liner is burnt by heat during solder reflow, or the release liner absorbs water during cleaning. There is a problem such as peeling off.

[0006] Therefore, in order to prevent peeling due to water absorption in the cleaning step, a paper laminated with a polymer material such as polyethylene is used as a base material. There is a problem in that the air trapped in the paper expands due to the heat of time to break through the laminate film or cause foaming, which causes problems in appearance.

Further, it has been practiced to use a plastic film such as polyethylene terephthalate or polyethylene as a substrate. However, according to this, the base material shrinks due to the heat during the solder reflow,
There is a problem that the FPC curls and parts such as ICs and chips are lifted up, making soldering difficult.

Furthermore, in the case of producing parts for calculators, copiers, televisions, automobiles, etc., when the parts are processed through a punching process, the surface of the release liner is contaminated with water, soapy water, oil or the like. Also, there is a problem that burr occurs on the double-sided tape due to punching.

An object of the present invention is to provide a release liner and a double-sided tape which solve the above-mentioned problems and can suppress damage, deformation, contamination and the like in processes such as solder reflow, punching and washing.

[0010]

The present inventors have found that the above-mentioned problems can be achieved by the present invention described below. That is, the release liner of the present invention is a release liner in which two or more base materials are adhered via a pressure-sensitive adhesive layer whose adhesiveness is reduced by heating. The double-sided tape of the present invention is a double-sided pressure-sensitive adhesive tape or sheet in which a pressure-sensitive adhesive layer is provided on the release liner with or without a release treatment layer.

[0011]

According to the present invention, the release liner is composed of at least two layers of base material and the base materials are adhered to each other so that they can be separated by heating. Even if contamination occurs, it is easily removed by peeling it by heating so that a beautiful lower layer can be exposed.

The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of the release liner and the double-sided tape of the present invention. In the figure, the release liner 1 comprises two layers of base materials 11a and 11b.
Is adhered by the adhesive layer 12,
An adhesive layer 2 is provided on the side surface of the base material 11b of the release liner 1. A release treatment layer (not shown) is preferably provided on the surface of the release liner 1 (the surface of the pressure-sensitive adhesive layer 2 side).

The base materials 11a and 11b are not particularly limited, and include, for example, paper such as western paper and Japanese paper, aluminum foil,
Various metal foils such as copper foil, stainless steel foil, iron foil, duralumin foil, tin foil, titanium foil, and gold foil, films made of various resins such as polyethylene, polypropylene, polyvinyl chloride, polyester, polyamide, polyurethane foam, vinyl foam, polyethylene Examples thereof include foams, foams such as styrene foam, non-woven fabrics, woven fabrics, felts, and films obtained by laminating these with a polymer material.

As the metal foil, one that can withstand the temperature during solder reflow (usually about 230 ° C.), for example, one having a melting point of 250 ° C. or higher, preferably 400 ° C. or higher is desirable.

As the polymer material for the laminate,
For example, polyethylene-based, polypropylene-based, ethylene-
Polymers such as vinyl acetate copolymer system, ethylene-acrylic acid copolymer system, ethylene-methacrylic acid copolymer system, ethylene-ethyl acrylate copolymer system, polyvinyl chloride system, polyvinylidene chloride system, or blends thereof. Addition polymerization type polymers such as copolymers, condensation type polymers such as polyethylene terephthalate type and polyethylene naphthalate type, and cellulose type polymers such as glassine paper, kraft paper and wood free paper can be used. The thickness of the polymer material for lamination is from the viewpoint of workability and workability.
It is preferably 200 μm or less, and more preferably 100 μm or less.

The thickness of the base materials 11a and 11b is not particularly limited, but is generally 5 μm to 5 mm, preferably 30 so that the mechanical strength, flexibility, etc. are appropriate.
It is suitable to set the thickness to about 100 μm.

In the present invention, as a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer 12 in FIG. 1) for adhering the respective substrates to each other, the property of reducing the adhesiveness by heating (hereinafter, this property is referred to as heat peeling property). The one with is used. The heat releasability of the pressure-sensitive adhesive layer can be obtained, for example, by making the pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer have a heat-foaming property, and according to this, by heating the pressure-sensitive adhesive layer to foam it. The adhesive strength of the pressure-sensitive adhesive can be reduced, and thus the substrate can be easily peeled off.

The heat-peelable pressure-sensitive adhesive layer is obtained, for example, by incorporating a foaming agent into the base polymer.

The above-mentioned base polymer has a high elasticity in order to have sufficient adhesive force before heating the adhesive and to sufficiently reduce the adhesive force after heating, for example, at room temperature. From 50 to 150 ℃ dynamic elastic modulus
10 to 10,000,000 dyne / cm ² , preferably 500 to 800
It is desirable to use the one with 10,000 dyne / cm ² . Furthermore, it is preferable to use a material having a small change in dynamic elastic modulus from room temperature to 150 ° C. (preferably within 5 times, preferably within 3 times).

The monomer component constituting the above base polymer is not particularly limited, and a monomer used in the preparation of known adhesives such as acrylic adhesives, rubber adhesives, styrene / conjugated diene block copolymer adhesives, etc. Any of the components can be used.

Specifically, methyl, ethyl, propyl,
It usually has 2 carbon atoms, such as butyl, 2-ethylhexyl, isooctyl, isononyl, isodecyl, dodecyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl.
Acrylic acid-based alkyl esters such as acrylic acid or methacrylic acid having 0 or less alkyl groups, acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Examples include N-methylol acrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether and the like.

Further, as the base polymer, natural rubber having the same degree of change in dynamic modulus and high elasticity as described above,
It is also possible to use recycled rubber, a UV-curable pressure-sensitive adhesive composition, or the like.

If desired, various additives such as a cross-linking agent, a tackifying resin, a plasticizer, a filler, and an anti-aging agent may be added to the above-mentioned pressure-sensitive adhesive. The gel content of the agent is 40% by weight or more, preferably 50% by weight or more,
It is more preferable that the amount is 70% by weight or more.

The adhesive strength of the above-mentioned pressure-sensitive adhesive layer is 0.4 N / so that each layer of the substrate before heating can be surely adhered.
It is desired to be 20 mm or more, preferably 0.8 N / 20 mm or more.

The foaming agent contained in the base polymer is not particularly limited, and various kinds of inorganic or organic foaming agents may be contained alone or in combination.

Examples of the inorganic foaming agent include water, ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides and the like.

Examples of the organic foaming agent include chlorofluoroalkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azo compounds such as azobisisobutyronitrile, azodicarbonamide and barium azodicarboxylate, and paratoluene. Sulfonyl hydrazide,
Diphenyl sulfone-3,3'-disulfonyl hydrazide,
4,4'-oxybis (benzenesulfonylhydrazide),
Hydrazine compounds such as allyl bis (sulfonyl hydrazide), p-toluylene sulfonyl semicarbazide,
Semicarbazide compounds such as 4,4'-oxybis (benzenesulfonyl semicarbazide), 5-morpholyl -1,
Triazole compounds such as 2,3,4-thiatriazole,
Examples thereof include N-nitroso compounds such as N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide.

As the foaming agent, butane, propane,
It is also possible to use heat-expandable particles obtained by microencapsulating a gasification component such as pentane, and according to this,
It is preferable in that the mixing operation is easy. Specific examples of the heat-expandable particles include microspheres (trade name; manufactured by Matsumoto Yushi Co., Ltd.). In addition, you may add a foaming auxiliary agent as needed.

The blending amount of the above-mentioned foaming agent is appropriately determined depending on the degree to which the adhesive force of the above-mentioned pressure-sensitive adhesive layer is reduced, but is usually 1 to 100 parts by weight, preferably 5 parts by weight with respect to 100 parts by weight of the base polymer. ˜50 parts by weight, more preferably 1
It is desirable to add about 5 to 30 parts by weight.

The heat-peelable pressure-sensitive adhesive layer has a thickness of 60 to 300.
It is desirable that the resin exhibits peelability by heating at 100 ° C, preferably 100 to 200 ° C. If the temperature at which the pressure-sensitive adhesive layer exhibits the heat-peelability is 60 ° C. or higher, the adhesive layer is less likely to be peeled except when it is heated for the purpose of peeling between the base materials. The heat treatment does not require a great deal of time, labor and cost.
The heat-peelable pressure-sensitive adhesive layer can be normally peeled off by heat during solder reflow when mounting parts such as ICs and connectors.

The thickness of the heat-peelable pressure-sensitive adhesive layer is not particularly limited, but it is generally about 5 to 200 μm, preferably 10 in order to make the pressure-sensitive adhesive force and the mechanical strength of the substrate sufficient. About 30 μm is appropriate

In the example shown in FIG. 1, two layers of base material are used, but three or more layers of base material may be used. In this case, the same heat-peelable pressure-sensitive adhesive layer as described above may be interposed between the base materials.

When three or more base materials are used as described above, the adhesive layer provided between the base materials is two or more,
It is also possible to provide a difference in temperature at which each of these pressure-sensitive adhesive layers exhibits thermal peeling property. For example, a three-layer substrate 11 such as the release liner and double-sided tape shown in FIG.
a, 11b and 11c are adhered by the adhesive layers 12a and 12b to form the release liner 1, and the adhesive layer 12a
Is set to be lower than the temperature at which the pressure-sensitive adhesive layer 12b exhibits heat peelability (for example, about 30 to 70 ° C. lower). According to this aspect, for example, by providing the pressure-sensitive adhesive layer 2 on the side surface of the base material 11c of the release liner 1 to form a double-sided tape, when using it,
The base material 11a (of the outermost layer) that has been damaged, deformed, or contaminated is heated to a specific temperature to be removed, and then the base material 1 is further added.
1b (substantially close to the outer layer side of the base material 11a),
When deformation, contamination, etc. occur, they can be removed by heating them to a temperature higher than the above temperature, and as a result, the base material 11c (the one closest to the adhesive layer 2) is protected again. Become.

For example, regarding the double-sided tape of FIG. 1, there is no particular limitation on the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 2 provided on the side surface of the base material 11b of the release liner 1, and an acrylic pressure-sensitive adhesive, a natural rubber-based pressure-sensitive adhesive, Any of the pressure-sensitive adhesives used for ordinary double-sided tapes such as synthetic rubber-based pressure-sensitive adhesives can be used, but acrylic pressure-sensitive adhesives are particularly preferable in terms of heat resistance and weather resistance.

If desired, the pressure-sensitive adhesive layer 2 may contain various additives such as a cross-linking agent, a tackifying resin, a plasticizer, a filler and an antioxidant.

The thickness of the adhesive layer 2 is not particularly limited,
From the viewpoint of adhesiveness, workability, etc., usually about 5 to 300 μm,
It is preferably about 20 to 180 μm. In addition,
The pressure-sensitive adhesive layer 2 may be composed of only a pressure-sensitive adhesive, but may have a structure having a pressure-sensitive adhesive on both sides of a suitable base material. In this case, the base material is paper, non-woven fabric, woven fabric or polyethylene,
A resin film such as polypropylene or polyethylene terephthalate is exemplified, and the thickness thereof is appropriately about 80 μm or less, preferably about 50 μm or less in view of heat resistance and processability.

The adhesive strength of the pressure-sensitive adhesive layer 2 is, for example, 5 N / 20 mm or more, preferably 8 N / 20 mm or more, so that parts can be fixed securely.

The release agent forming the release treatment layer provided between the release liner and the double-sided tape may be any release agent that can impart the required release force to the surface, and any of those known in the art are preferred. Is also used. For example, long-chain alkyl-containing polymers, silicones, polyolefins, etc. are exemplified. Furthermore, as the silicone, a condensation reaction type,
Thermosetting silicone such as addition reaction type, electron beam curing type,
A radiation curable silicone such as an ultraviolet curable type is exemplified. The thickness of the peeling treatment layer is about 0.01 to 5 μm, preferably 0.03 to 5 μm from the viewpoint of peeling force.
About 3 μm (amount of release agent applied is about 0.01 to 5 g / m ² ,
It is preferably about 0.03 to 3 g / m ² ).

FIG. 3 is a schematic sectional view showing an example of another release liner and double-sided tape of the present invention. In the example shown in the figure, a release liner 3 is attached to the surface of the pressure-sensitive adhesive layer 2 of the double-sided tape shown in FIG. 1 to form a double-sided tape.

The upper release liner 3 is not particularly limited, and is usually one such as paper, non-woven fabric, woven fabric, or a substrate made of a resin film such as polyethylene, polypropylene, polyethylene terephthalate, etc., which has been subjected to a release treatment. Can be used. The release liner 3 of the present invention can be used as the release liner 3 on the adherend side, and when the release liner 3 is damaged or contaminated, it can be easily removed.

The release liner of the present invention may be used for a label, a seal, a sticker, a wallpaper, an adhesive sheet, etc., in addition to the double-sided tape.

[0042]

The present invention will be described in more detail below with reference to examples, but it goes without saying that the present invention is not limited to these examples.

Example 1 (Preparation of Release Liner) A structure having the same structure as that shown in FIG. 1 (a release treatment layer was provided between the substrate 11b and the pressure-sensitive adhesive layer 2) was obtained. An addition reaction type thermosetting silicone [manufactured by Shin-Etsu Chemical Co., Ltd .; product number KS-774; PL-3 as a curing catalyst (Shin-Etsu Chemical Co., Ltd.) on one surface of a high-quality paper (base material 11b) weighing 70 g / m ² Used) is applied so that the coating weight after drying is 0.5 g / m ^2, and the temperature is 145 ° C.
Peeling layer (not shown) after being dried and cured for 30 seconds
Was provided. Then, in a toluene solution containing 100 parts by weight of an acrylic copolymer consisting of 100 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid and 10 parts by weight of acrylonitrile, heat-expandable fine particles (trade name Microsphere F
-F50D; manufactured by Matsumoto Yushi Co., Ltd.) to prepare 30 parts by weight of an adhesive to prepare a pressure-sensitive adhesive on one surface of a fine paper (base material 11a) weighing 70 g / m ² which is different from the above. The pressure-sensitive adhesive layer 12 was formed by coating and drying so as to have a thickness of 30 μm. Then, the surface of the base material 11a on which the pressure-sensitive adhesive layer 12 is formed,
The base material 11b was attached to the side opposite to the release treatment layer forming surface to obtain a release liner 1 having a width of 200 mm and a length of 300 mm.

(Preparation of double-sided tape) In order to have the same construction as that shown in FIG. 3, another weight of 70 g / m ² was applied to one surface of a high-quality paper, and an addition reaction type thermosetting silicone was used as product number KS. A release liner 3 was obtained by performing a silicone treatment in the same manner as in the case of the base material 11b except that the product number KS-772 was used instead of -774. Then, on the silicone-treated surface of the release liner 3, the thickness after drying 50
An acrylic pressure-sensitive adhesive was applied so as to have a thickness of μm and dried to form a pressure-sensitive adhesive layer 2. Then, the pressure-sensitive adhesive layer 2 was attached to a release treatment layer (not shown) provided on the release liner 1 to prepare a double-sided tape.

Comparative Example 1 A release liner and a double-sided tape were produced in the same manner as in Example 1 except that the base material 11a was not attached to the base material 11b and the base material 11b was used as a release liner.

Example 2 In the above Example 1, the base material 11a and the base material 11b were used.
The release liner 1 and the double-sided tape were produced in the same manner except that each was changed to a polyethylene terephthalate film having a thickness of 50 μm.

Comparative Example 2 A release liner and a double-sided tape were produced in the same manner as in Example 2 except that the base material 11a was not attached to the base material 11b and the base material 11b was used as a release liner.

Example 3 In Example 1 above, the adhesive of the adhesive layer 12 was added to 100 parts by weight of a base polymer made of acrylic rubber containing 20 parts by weight of acrylic (methyl methacrylate) and 20 parts by weight of a terpene-based tackifier. Parts, high softening point resin [Tamanor 8
03L (trade name; manufactured by Arakawa Chemical Industry Co., Ltd .; Tg 160 ° C)]
60 parts by weight, crosslinking agent [Takenate L1150 (trade name;
Takeda Yakuhin Kogyo Co., Ltd.)] 2 parts by weight and 50 parts by weight of heat-expandable fine particles (trade name: Microsphere F-80SD; Matsumoto Yushi Co., Ltd.) were used in the same manner except that the adhesive was prepared. And the double-sided tape was produced.

Comparative Example 3 A release liner and a double-sided tape were prepared in the same manner as in Example 3 except that the base material 11a was not attached to the base material 11b and the base material 11b was used as a release liner.

Example 4 A release liner and a double-sided tape were produced in the same manner as in Example 1 except that the base material 11b was changed to an aluminum foil having a thickness of 50 μm.

Comparative Example 4 A release liner and a double-sided tape were produced in the same manner as in Example 4 except that the base material 11a was not attached to the base material 11b and the base material 11b was used as a release liner.

Comparative Example 5 A release liner and a double-sided tape were produced in the same manner as in Example 1 except that the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 12 was not blended with heat-expandable fine particles.

(Evaluation of Release Liner) Each of the double-sided tapes obtained in the above-mentioned Examples and Comparative Examples was subjected to ordinary FPC.
Then, the release liner was evaluated by the following method, and the results shown in Table 1 were obtained. Workability The part to which the double-sided tape of FPC was attached was punched out by a punching machine to make a sample, and its workability was evaluated. Water resistance After the above-mentioned test, the sample is subjected to a maximum surface temperature of 230.
60 by an infrared heating device so that it is kept at ℃ for 5 seconds
It was heated for 2 seconds, then immersed in warm water at 60 ° C., subjected to ultrasonic waves for 3 minutes and then pulled up, and the presence or absence of water immersion in the substrate 11b was observed to evaluate the water resistance. Peelability and surface condition After this, the base material 11a of the release liner 1 of each of Examples 1 to 4 and Comparative Example 5 was subjected to a speed of 30 cm / min and an angle of 180.
Peeling was performed at ° and the peelability was evaluated. Furthermore, after this, the surface state of the base material 11b including each of Comparative Examples 1 to 4 was observed.

[0054]

[Table 1]

In the above evaluation test, in Comparative Example 4, it was confirmed that the aluminum foil had a float (and a wrinkle) after punching. It is considered that this floating also affects the water resistance. In the evaluation test, it was difficult to peel the base material 11a in Comparative Example 5. Comparative Example 1
In Nos. 3 to 3, charring occurred on the surface of the base material 11b, and the surface condition was judged to be poor. In Comparative Example 5, since it is difficult to peel off the base material 11a as described above, the surface condition of the base material 11a is changed.
When judged by the surface condition of a, it was judged that the surface was charred and the surface condition was poor. In Comparative Example 4, no charring was observed, but oil contamination was observed.

[0056]

As described above in detail, in the present invention, the base material of the release liner is composed of at least two layers of base materials, and each base material is adhered so that its adhesive force is reduced by heating. Therefore, even if the base material on the outer layer side is damaged, deformed, or contaminated, it can be easily removed by peeling it by heating. Therefore, the base material on the inner layer side can be substantially used as the base material of the release liner, and the base material on the outer layer side can protect the base material from damage, deformation, contamination and the like.

Therefore, solder reflow, punching,
A release liner and a double-sided tape that can suppress damage, deformation, contamination, etc. in processes such as washing are obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a release liner and a double-sided tape of the present invention.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the release liner and the double-sided tape of the present invention.

FIG. 3 is a schematic sectional view showing still another embodiment of the release liner and the double-sided tape of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of a conventional release liner.

[Explanation of symbols]

 1 Release liner 11a, 11b, 11c Substrate 12, 12a, 12b Adhesive layer 2 Adhesive layer 3 Release liner

Claims (3)

[Claims] 1. A release liner in which two or more base materials are adhered via a pressure-sensitive adhesive layer whose adhesiveness is reduced by heating. 2. The release liner according to claim 1, wherein the pressure-sensitive adhesive layer has a heat-foaming property. 3. A double-sided pressure-sensitive adhesive tape or sheet comprising a pressure-sensitive adhesive layer provided on the release liner according to claim 1, with or without a release treatment layer.