JPH05247418A - Foamable adhesive sheet and its production - Google Patents

Abstract

PURPOSE:To obtain a foamable adhesive sheet which can hold an article by bonding without falling off until the achievement of an objective, can be readily separated without a damage to the article after the achievement of the objective and whose part unnecessary for holding the article by bonding exhibits scarcely any adhesive force so that the articles can be laid on top of another for storage in a state wherein they are held by bonding by the sheet and to obtain a method for producing the sheet. CONSTITUTION:A foamable adhesive sheet having at least on one side of a supporting base material 1 an adhesive layer 2 which contains a foaming agent and whose adhesive force decreases, wherein the adhesive layer 2 consists of a part 21 treated to decrease the adhesive force and an untreated part 22; and a method for producing the sheet, wherein heat shielding masks 3 are provided on the adhesive layer 2 so that the adhesive layer 2 is heated through the masks 3 for treatment to decrease the adhesive force. The sheet can protect the articles held by bonding from impact, etc., and can prevent troubles due to adherence to operating machinery in an automatic bonding line, a working line, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamable adhesive sheet suitable for carrying articles, fixing articles during processing and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, a foamable adhesive sheet has been known in which a supporting substrate is provided with a pressure-sensitive adhesive layer containing a foaming agent and having a reduced adhesive force (JP-A-56-61468). This is one in which a pressure-sensitive adhesive layer containing a foaming agent is heated to achieve adhesive strength reduction treatment after achieving the purpose of adhering an article so that the article can be easily separated. It is used for a wide variety of purposes, such as transportation and fixing during processing.

However, the exposed surface of the adhesive layer, which is not used for the adhesive holding of the articles, exhibits a strong adhesive force, and when the articles are adhered and held and stacked, it becomes difficult to strongly adhere and peel off the upper and lower parts. Therefore, there was a problem that it could not be stored in a stacked state.

[0004]

SUMMARY OF THE INVENTION According to the present invention, an article is adhered and held without dropping until the purpose is achieved, and after the purpose is achieved, the ability to be easily separated without damaging the article is maintained, while the article is maintained. It is an object of the present invention to obtain a foamable adhesive sheet which does not exhibit an adhesive force substantially in the adhesive layer portion unnecessary for adhesive holding and can be stacked and stored in a state where the articles are adhesively held, and a manufacturing method thereof.

[0005]

According to the present invention, a supporting base material has a foaming agent-containing adhesive strength-reducing adhesive layer on at least one side thereof, and the adhesive strength-reducing adhesive layer has an adhesive strength-reducing portion and an untreated portion. A foaming adhesive sheet characterized by comprising a portion and a heat mask on an adhesive strength reducing type adhesive layer containing a foaming agent provided on at least one side of a supporting base material, and reducing the adhesive strength via the thermal mask. The present invention provides a method for producing the foamable adhesive sheet, which comprises heating the mold adhesive layer to reduce the adhesive strength.

[0006]

The function of the adhesive force reduction type adhesive layer is such that the foaming agent contained therein expands or foams to reduce or eliminate the adhesive force by the adhesive force reduction treatment by heating. By performing heat treatment via, it is possible to prevent or suppress the progress of the reduction of the adhesive force in the portion covered with the thermal mask, and thus it is possible to obtain the foamable adhesive sheet which partially maintains the adhesive force.

As a result of the above, it is possible to obtain a foamable adhesive sheet in which only the portion desired to be used for the adhesive holding of the article is left as the unbonded force reduction treated portion through the thermal mask. Then, after the purpose of holding the adhesive is achieved, the remaining untreated portion is subjected to the adhesive strength reduction treatment by the heat treatment again, so that the article can be easily separated without damaging the article.

[0008]

EXAMPLE FIG. 1 illustrates the foamable adhesive sheet of the present invention. Reference numeral 1 is a supporting substrate, 2 is a foaming agent-containing adhesive strength reduction type adhesive layer, 21 is an adhesive strength reduction treated portion, and 22 is an untreated portion.

As the supporting base material, an appropriate material such as a plastic film, paper, woven cloth, non-woven cloth or felt, metal foil, foamed material, or a laminated body thereof is used. The thickness is generally 10 μm to 5 mm, but is not limited to this. A foamable adhesive sheet may be used in which a separator made of a thin sheet or the like treated with a release agent is used as a supporting substrate so that the adhesive force reduction type adhesive layer can be appropriately transferred. The support base material may have a feeding force receiving portion including a feed hole such as a sprocket hole and an engagement groove with a gear.

An appropriate adhesive can be used to form the adhesive force reduction type adhesive layer, and a pressure sensitive adhesive or the like is generally used. As the pressure-sensitive adhesive, an appropriate material such as a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a styrene / conjugated diene block copolymer-based pressure-sensitive adhesive can be used. Etc. can be used (JP-A-56-61468, JP-A-61-174857, JP-A-63-17981).

In addition, those which have 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 a sufficient adhesive strength by heating. A pressure sensitive adhesive or the like can also be used (Japanese Patent Publication No. 56-
13040). The pressure-sensitive adhesive may be a mixture of appropriate additives such as a cross-linking agent, a tackifying resin, 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 synthetic rubber as a base polymer, methyl group, ethyl group, propyl group, butyl group, 2-ethylhexyl group, isooctyl group, isononyl group, Usually, such as isodecyl group, dodecyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and eicosyl group, such as acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms, Acrylic acid alkyl ester, acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Acrylic pressure-sensitive adhesive based on an acrylic polymer containing N-methylolacrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, etc. Etc.

[0013] A balance between the adhesive force (article holding force) before the adhesive force reduction process and the adhesive force decreasing property (easy to separate the items) due to the adhesive force reduction process, and the adhesive holding product when it is used as a wound material. The pressure-sensitive adhesive which can be preferably used from the viewpoint of adhesion followability, etc., has a dynamic elastic modulus of 500,000 to 10,000,000 dyne / cm ² , preferably 50, at room temperature to 150 ° C.
The base polymer is a highly elastic polymer in the range of 10 to 8 million dyne / cm ² . Highly elastic polymers that are more preferable as the base polymer are those having a small change rate of the dynamic elastic modulus from room temperature to 150 ° C., and in particular, those having a change degree of 5 times or less.

The adhesive strength-reducing adhesive layer can be formed by blending an adhesive with a foaming agent. By blending the foaming agent, it is possible to form an adhesive layer in which the adhesive strength is reduced or disappears due to expansion or foaming of the contained foaming agent by heat treatment. When the pressure sensitive adhesive at the time of heat is used, a foaming agent that expands or foams at a temperature higher than the bonding treatment temperature of the adhesive is used. The blending amount of the foaming agent may be appropriately determined according to the degree to which the adhesive force is reduced. Generally 1 to 100 parts by weight, preferably 5 per 100 parts by weight of base polymer.
-50 parts by weight, especially 10-40 parts by weight.

The blowing agent used is not particularly limited,
Various inorganic or organic foaming agents can be used. As typical examples of the inorganic foaming agent, ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite,
Examples thereof include sodium borohydride and azides.

Typical examples of organic blowing agents include water, fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, and azo compounds such as azobisisobutyronitrile, azodicarbonamide and barium azodicarboxylate. Compounds, hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonylhydrazide, 4,4′-oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide), ρ-toluylenesulfonyl semicarbazide and Semicarbazide compounds such as 4,4′-oxybis (benzenesulfonyl semicarbazide), triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole, N, N′-dinitrosopentamethylenetetrami And N, N'-dimethyl -
Examples thereof include N-nitroso compounds such as N, N'-dinitrosoterephthalamide.

The heat-expandable fine particles obtained by encapsulating the foaming agent in microcapsules are preferably used because the mixing operation is easy. As the heat-expandable fine particles, there are commercially available products such as Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.). In the present invention, a foaming aid may be added if necessary.

The adhesive strength-reducing adhesive layer is formed, for example, by a method of coating and forming a foaming agent-containing adhesive layer on at least one side of a supporting substrate, or by using a foaming agent-containing adhesive layer coated and formed on a separator as a support substrate. A suitable method such as a method of transferring the material to at least one side can be used. The thickness of the adhesive strength reduction type adhesive layer to be provided may be appropriately determined. Generally 500μ
m or less, especially 5 to 200 μm.

In the production of the foamable adhesive sheet of the present invention, for example, as shown in FIG. 2, a thermal mask 3 is provided on a foaming agent-containing adhesive strength reducing adhesive layer 2, and the adhesive strength is reduced through the thermal mask 3. This can be carried out by, for example, a method of heating the mold adhesive layer with an appropriate heat source such as far infrared rays to partially reduce the adhesive strength. The heating conditions may be appropriately determined depending on the foaming characteristics of the foaming agent and the heat resistance of the supporting base material.

As shown in FIG. 1, the formed adhesive force reduction treated portion 21 is higher than the untreated portion 22 covered with the thermal mask by expansion (foaming) by the foaming agent, and the article is adhered to the untreated portion. When it is held, it can function as a cushioning protective layer around the article. In the case of a thin-layer article, it can also function as a protective layer for the thin-layer article during stacking.
Therefore, in the present invention, an adhesive or the like which requires a heat-bonding treatment such as a heat-sensitive adhesive or a pressure-sensitive adhesive when hot is also preferably used.

The heat mask used is, for example, a heat-reflecting material such as metal or a heat-ray reflecting filter, a carbon or liquid impregnated sheet, a heat-absorbing material such as a heat-ray absorbing filter, a heat insulating material such as foam, or a coolant such as a refrigerant sheet. It can be appropriately formed by using a heat-shielding material such as

The thermal mask may be a single plate formed in the desired non-adhesive strength reduction treatment form, or may be a connected body in which such single plates are appropriately connected. It is also possible to use a film having a good heat transfer property or a mask sheet in which a heat mask portion is pattern-formed on a base sheet that transmits a heat ray transmitting filter. The integrated body of the thermal mask consisting of such a connected body or a mask sheet can efficiently attach the thermal mask to the adhesive strength reduction type adhesive layer when continuously forming a uniform pattern, and after the adhesive strength reduction treatment. There is an advantage that peeling and removal can be efficiently performed.

The expandable adhesive sheet of the present invention can be provided as a thermal mask provided on a predetermined portion of the adhesive strength reduction type adhesive layer. In that case, the adhesive strength reduction type adhesive layer may be partially finished with the adhesive strength reduction treatment or may be untreated. The thermal mask is effective for preventing contamination of the adhesive strength reduction type adhesive layer. In addition, when the adhesive strength reduction type adhesive layer is provided on one side of the supporting substrate, a foamable adhesive sheet in which an adhesive layer of a pressure sensitive property which is not a typical adhesive force reduction type adhesive layer is provided on the other side is also formed. You can

In the foamable adhesive sheet of the present invention, the portion left as a non-adhesive strength reduction treated portion through the thermal mask is a portion that can be used for adhesive holding of the article in a state where the thermal mask is peeled off. Such an untreated portion is heated and subjected to an adhesive strength reduction treatment after achieving the purpose of holding the adhesiveness of the article. As a result, the articles that have been adhered and held can be easily separated and collected. The heating conditions may be appropriately determined depending on the foaming characteristics of the foaming agent and the heat resistance of the supporting base material. Such heat treatment can be performed at an appropriate stage depending on the purpose of use.

The article may be adhered and held in an arbitrary arrangement. By the way, in the transportation between the steps in the automatic assembly line, it is advantageous that the transported articles are adhered and held at regular intervals and in the same direction. Therefore, the foamable adhesive sheet can be used in an appropriate shape such as a long body such as a carrier tape or a large area plate, and the shape and arrangement pattern of the unbonded force reduction treated portion to be formed can be appropriately determined. You can The adhesive holding treatment of the article to the non-adhesive strength reduction treated portion can be appropriately performed depending on the adhesive property of the adhesive strength reduction type adhesive layer, such as a simple compression treatment or a thermocompression treatment.

The expandable adhesive sheet of the present invention is preferably used in various applications where it is desired to easily peel (separate) the article from the expandable adhesive sheet after the article is adhered and held to achieve the purpose. .. The purpose of adhering and holding the articles is arbitrary, for example, transportation between processes in an automatic assembly line, transportation purpose such as transportation from a maker to a user, stocking purpose such as storage, and fixing or temporary fixing of articles during processing. ..

Therefore, the article to be adhered and held is also optional. Examples include electrical components such as ceramic capacitors, oscillators and resistors, display devices such as liquid crystal cells and plasma displays, electronic components such as solar cells, thermal heads, printed circuit boards and semiconductor chips, and optical components such as polarizing plates. Examples of the material include easily damaged articles such as a magnetic head and a glass plate.

By holding a printed circuit board such as an FPC at regular intervals via a carrier tape, it is possible to easily confirm the number of products to be delivered and to automate the assembly into electronic equipment. It is possible to overcome problems such as the confirmation of the number of delivered products by the bundled delivery form and the difficulty of automation when incorporating the electronic device.

Further, the easily-damaged articles such as the polarizing plate, the magnetic head, and the glass plate have not been able to adopt the transportation system by the adhesive holding method due to the damage problem at the time of peeling or transportation, but the present invention According to this, it is possible to carry under buffer protection by the non-adhesive holding portion 21 illustrated in FIG. 2, and it is possible to adopt a carrying system by adhesive holding.

Example 1 100 parts of a base polymer having a weight average molecular weight of 1.2 million and consisting of a copolymer of 100 parts of butyl acrylate (parts by weight, the same applies hereinafter), 5 parts of acrylic acid and 10 parts of acrylonitrile, and heat-expandable fine particles (micro) Sphere F-80SD)
Prepare a toluene solution of an adhesive that contains 15 parts,
It is coated on a 25 μm-thick polyester film so that the thickness after drying is 30 μm, and heat-dried. Then, FeO-phosphate glass-based heat wire is applied on the central part of the adhesive strength reduction type adhesive layer (20 cm × 20 cm). Absorption filter (10 cm x 10
cm) was adhered and heat-treated at 150 ° C. for 1 minute to obtain a foamable adhesive sheet in which the outer periphery of the heat ray absorption filter was subjected to adhesive strength reduction treatment.

Example 2 100 parts of a base polymer made of an acrylic graft rubber (20 parts of acrylic: MMA), 10 parts of a terpene-based tackifying resin, 60 parts of a high softening point resin having a Tg of 180 ° C., 2 parts of a vulcanizing agent, Heat-expandable fine particles (Microsphere F-80S
D) A toluene solution of an adhesive prepared by mixing 50 parts is prepared and applied to one side of a 25 μm-thick polyester film so that the thickness after drying is 30 μm, and heat-drying treatment to reduce the adhesive strength. A foamable adhesive sheet was obtained in the same manner as in Example 1 except that the layers were formed.

Example 3 100 parts of an adhesive consisting of 50 parts of ethyl acrylate and 50 parts of 2-ethylhexyl acrylate (adhesion temperature 100 ° C.)
Adhesive consisting of 20 parts of heat-expandable fine particles (Microsphere F-50D) is applied to one side of a 50 μm thick polyester film so that the thickness after drying is 30 μm, and heated. According to the same manner as in Example 1, a foamable adhesive sheet was obtained using a heat mask having a heat ray reflective layer made of a silver vapor-deposited film.

Evaluation Test Adhesive Strength The FeO-phosphate glass heat ray absorbing filter or heat mask was peeled off from the foamable adhesive sheets obtained in the examples, and the stainless steel plate (SUS 304 in the adhesive strength-reduced portion and untreated portion) was removed. The adhesive force (180 degree peel) to the BA finished surface) was measured according to JIS Z 0237. However, the adhesive strength in the untreated portion in the case of Example 3 was heat-bonded at 100 ° C., and the adhesive strength at room temperature was examined in the adhesive reduction treatment portion and in the other examples.

Stackability 10 foamable adhesive sheets obtained in the examples were stacked and left on for 1 week under a uniform load of 1 kg / cm ^2.
(Room temperature), then the stack was unwound and the peelability at that time was evaluated. The evaluation criteria were ◯ when each expandable adhesive sheet could be easily separated without breakage or damage when unstacking, and X when broken or damaged during separation.

The above results are shown in Table 1. The table also shows the thicknesses of the adhesive strength reduction treated portion and the untreated portion.

[Table 1]

[0036]

EFFECTS OF THE INVENTION According to the present invention, an adhesive region capable of reducing the adhesive force capable of holding an article in an adhesive state, and a non-adhesive region which is thicker than the region and has a cushioning protection function and which exhibits substantially no adhesive force. It is possible to obtain a foamable adhesive sheet having areas in a desired shape.

As a result of the above, until the holding purpose is achieved, the articles are adhered and held without being dropped, and after the purpose is achieved, they can be easily separated without damaging the articles and can be easily handled and stacked through the non-adhesive area. It is also possible to obtain a foamable adhesive sheet that can be easily separated from the upper and lower sides without substantially adhering and that protects the adhesive holding article from impact or the like. Such characteristics enable stacking and storage and prevent adhesion troubles with an operating machine in an automatic adhesion line or a processing line.

Therefore, it is possible to adopt a system such as transportation by adhesion holding even for a easily damaged article or the like which could not adopt the adhesive holding method due to a breakage problem at the time of separation or transportation.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a foamable adhesive sheet.

FIG. 2 is a plan view illustrating a manufacturing process.

[Explanation of symbols]

 1: Supporting substrate 2: Adhesive strength-reducing adhesive layer containing a foaming agent 21: Adhesive strength-reduced portion 22: Untreated portion 3: Thermal mask

Claims (3)

[Claims] 1. A support base material having a foaming agent-containing adhesive strength reduction type adhesive layer on at least one side thereof, and the adhesive strength reduction type adhesive layer comprises an adhesive strength reduction treated portion and an untreated portion. Foamable adhesive sheet to do. 2. A support base material is provided with a foaming agent-containing adhesive strength reduction type adhesive layer on at least one side, and a thermal mask is provided at a predetermined portion on the adhesive strength reduction type adhesive layer. Foamable adhesive sheet. 3. A thermal mask is provided on an adhesive strength reducing adhesive layer containing a foaming agent, which is provided on at least one side of a supporting substrate, and the adhesive strength reducing adhesive layer is heated through the thermal mask to reduce the adhesive strength. It processes, The manufacturing method of the foamable adhesive sheet of Claim 1 characterized by the above-mentioned.