JP3040587B2 - Foam release sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam-peelable sheet which can form at least three stages of adhesive strength including an intermediate high adhesive strength, which is suitable for fixing or transporting articles during processing.

[0002]

2. Description of the Related Art There has been known a foam-peelable sheet comprising a supporting base material provided with a pressure-sensitive adhesive layer containing a foaming agent (JP-A-56-61468). In this method, after the purpose of bonding the article is achieved, the pressure-sensitive adhesive layer containing the foaming agent is heated to reduce the adhesive strength so that the article can be easily separated. It is used for a variety of purposes, such as fixing during processing and the like, and physical distribution such as transportation.

However, there is a problem that the usable range is narrow, and it is usually necessary to form a pressure-sensitive adhesive layer containing a foaming agent having a different composition for each purpose of use and to repeatedly bond and separate the articles. That is, for example, in the case of performing a cutting process after pattern printing is applied to an article, since the performance required for the foam release sheet is different between the time of pattern formation and the time of cutting, different foam release properties for pattern formation and for cutting are used. It is necessary to repeat the separation / adhesion of the article when preparing the sheet and shifting from pattern formation to cutting, which is not efficient.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a foam-peelable sheet which can be used in a plurality of steps while maintaining a single adhesive sheet while adhering and holding the article, thereby eliminating the need for repeated work of separating and adhering the article and the adhesive layer. The task is to obtain a sheet.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a heat treatment is carried out at different temperatures by containing at least one side of a support base material containing at least two kinds of foaming agents having different treatment temperatures and an elasticity improver for high temperature treatment. The present invention provides a foam-peelable sheet having a foaming agent-containing adhesive layer that forms at least three stages of adhesive force states from an intermediate state of high adhesive force to a reduced adhesive force state.

[0006]

By forming an adhesive layer containing two or more types of foaming agents having different processing temperatures, it is possible to form two or more stages of adhesive strength based on a change in the processing state of the foaming agent by heating at different temperatures. In the expanded or foamed state, the adhesive strength can be made higher than in the initial state. On the other hand, in the state of high expansion or foaming, the adhesive strength is usually reduced, but the elasticity of the adhesive layer is improved when a high expansion (foaming) state is formed by high temperature treatment in combination with an elasticity improver. By doing so, the adhesive force can be further reduced, and an adhesive state can be obtained in which the article held and held can be easily separated without damaging the article.

Accordingly, it is possible to obtain a foaming agent-containing adhesive layer that forms at least three stages of adhesive force states through an intermediate state of high adhesive force and a reduced adhesive force state by heat treatment at different temperatures. In the intermediate state, the buffer function is improved by expansion of the foaming agent due to the heat treatment. As a result of the above, for example, an article is adhered and held on the foaming agent-containing adhesive layer in the initial state, and then subjected to pattern printing, and then subjected to heat treatment while maintaining the adhesive state to bring the adhesive layer into an intermediate state, and necessary processing steps such as cutting. And the separation and bonding of the articles can be omitted.
In that case, the buffer function is improved in the intermediate state, so that it functions favorably in a step requiring impact resistance such as cutting.

[0008]

FIG. 1 illustrates a foam release sheet of the present invention. 1 is a supporting substrate, 2 is a foaming agent-containing adhesive layer, and 3 is an article held and bonded. In the present invention, the foaming agent-containing adhesive layer may be provided on both sides of the supporting substrate.

[0009] As the supporting base material, an appropriate material such as a plastic film, paper, woven fabric, nonwoven fabric or felt, metal foil, foam, or a laminate thereof can be used. The thickness is generally from 10 μm to 5 mm, but is not limited to this. A foamed release 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 support substrate so that the adhesive layer can be appropriately transferred.

For forming the foaming agent-containing adhesive layer, an appropriate adhesive can be used. In general, a pressure-sensitive adhesive or the like is used in order to obtain an adhesive exhibiting adhesive strength at room temperature. As pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives,
Appropriate materials such as styrene / conjugated diene block copolymer pressure-sensitive adhesives can be used, and UV-curable adhesives can also be used (JP-A-56-61468, JP-A-61-174857). JP-A-63-1798
No. 1).

[0011] Further, those containing a hot-melt resin having a melting point of about 200 ° C or less to improve the creep property, or those having a small adhesive strength at room temperature and having a sufficient adhesive strength developed by heating. A pressure-sensitive adhesive or the like may be used (Japanese Patent Publication No. 56-
No. 13040). In addition, the pressure-sensitive adhesive may be one in which appropriate additives such as a cross-linking agent, a tackifier resin, a plasticizer, a filler, an antioxidant, and the like are blended as necessary.

More specifically, for example, a rubber-based pressure-sensitive adhesive having a base polymer of natural rubber or synthetic rubber, a methyl group, an ethyl group, a propyl group, a butyl group, a 2-ethylhexyl group, an isooctyl group, an isononyl group, Such as acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms such as isodecyl group, dodecyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and eicosyl group. Acrylic acid alkyl esters, acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Acrylic pressure-sensitive adhesive having a base polymer of an acrylic polymer containing N-methylolacrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, and the like as components. And so on.

When the foaming agent-containing adhesive layer is heat-treated to an intermediate expanded (foamed) state, the adhesive strength is improved (holding power and cushioning property of the article), and when the heat-treated to the final expanded (foamed) state. Of adhesive strength (separation of articles)
Pressure-sensitive adhesives that can be preferably used from the viewpoint of the balance between them are, for example, acrylic, rubber-based, and silicone-based adhesives, and may include an appropriate auxiliary agent for improving the elastic modulus according to them.

The foaming agent-containing adhesive layer can be formed by blending two or more kinds of foaming agents having different processing temperatures with an adhesive and an elastic modulus improving agent for high-temperature processing. This makes it possible to form at least three levels of adhesive strength by heat treatment at different temperatures. When a hot pressure-sensitive adhesive or the like is used, a foaming agent that expands or foams at a temperature higher than the bonding temperature of the adhesive is used.

The amount of the foaming agent may be appropriately determined according to the degree to which the adhesive layer is expanded (foamed) in an intermediate state or the degree to which the adhesive strength is reduced. Generally, 1 to 1 per 100 parts by weight of the base polymer is used for various types of the foaming agent to be used.
00 parts by weight, preferably 5 to 40 parts by weight, especially 10 to 3 parts by weight
0 parts by weight are blended.

The foaming agent used is not particularly limited.
Various inorganic or organic foaming agents can be selected and used so that at least two kinds of processing temperatures for low-temperature processing and high-temperature processing are combined. The temperature difference given to the processing temperature is appropriately determined according to the processing accuracy such as the temperature-sensitive characteristics of the foaming agent, but is generally 20 to 100 ° C., preferably 30 to 70 ° C.
Is the processing temperature difference.

Examples of commonly used inorganic foaming agents include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides and the like.

Examples of commonly used organic blowing agents include water, chloroalkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate. Azo compounds such as paratoluenesulfonylhydrazide and diphenylsulfone-3,3 '
Hydrazine compounds such as disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide) and allyl bis (sulfonyl hydrazide); semicarbazide compounds such as ρ-toluylenesulfonyl semicarbazide and 4,4'-oxybis (benzenesulfonyl semicarbazide) Compounds, triazole-based compounds such as 5-morpholyl-1,2,3,4-thiatriazole, N, N ′
N-nitroso compounds such as -dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide.

The heat-expandable fine particles obtained by microencapsulating a foaming agent are preferably used in view of easy mixing operation. The heat-expandable fine particles include commercially available products such as microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.). In the present invention, a foaming aid may be added as necessary.

As the elastic modulus improver, for example, a crosslinking agent or a photo-curing accelerator which starts improving the elastic modulus of the adhesive layer at the highest heating temperature at which the foaming agent in the adhesive layer is treated is used. As the cross-linking agent, for example, an isocyanate-based compound, an epoxy-based compound, a melamine-based compound, a peroxide-based compound, a sulfur-based compound, a diazo-based compound, a resin-based compound, or the like can be used as appropriate depending on the processing temperature or the like.

More specifically, for example, isocyanates such as aromatic isocyanate compounds such as toluene diisocyanate, hydrocarbon isocyanate compounds such as hexamethylene diisocyanate, alicyclic isocyanate compounds such as isophorone diisocyanate, and addition products thereof. Crosslinking agents, bisfinol A epoxy compounds, saturated hydrocarbon compounds containing glycidyl groups, etc., epoxy crosslinkers such as polymers with glycidyl groups, etc., peroxide crosslinking such as benzoyl peroxide, cumene hydroxy peroxide, etc. And a resin-based crosslinking agent such as an alkylphenol resin.

The amount of the elastic modulus improver may be appropriately determined according to the degree to which the adhesive strength of the adhesive layer is finally reduced. Generally, 0.01 to 40 parts by weight, preferably 0.1 to 40 parts by weight per 100 parts by weight of the base polymer in the adhesive.
10 parts by weight, preferably 0.3 to 5 parts by weight.

The foam-peelable sheet is formed, for example, by a method of coating and forming an adhesive layer containing a different kind of foaming agent and an elastic modulus improving agent on a support substrate, and by forming a different kind of foaming agent coated on a separator and improving the modulus of elasticity. It may be performed by an appropriate method such as a method of transferring a foaming agent-containing adhesive layer containing an agent. The thickness of the foaming agent-containing adhesive layer to be provided may be appropriately determined, and is generally 500 μm.
m or less, especially 5 to 200 μm. When a foaming agent-containing adhesive layer containing a heterogeneous foaming agent and an elastic modulus improving agent is provided on one side of the supporting base material, the other side contains one kind of foaming agent or does not contain a foaming agent. An adhesive layer may be provided.

The foam-peelable sheet of the present invention is applied, for example, by bonding and holding the article 3 to the untreated foaming agent-containing adhesive layer 2 as shown in FIGS. After performing printing or the like (FIG. 1), the foaming agent-containing adhesive layer 2 for bonding and holding the same is subjected to heat treatment to expand (foam) the foaming agent for low-temperature treatment, thereby improving the adhesive strength.
Then, measures for the next purpose such as cutting are performed (FIG. 2). Then, after the intended measures are sequentially taken as the next intermediate treatment state at a predetermined heating temperature according to the number of types of the contained foaming agent, the remaining foaming agent for high temperature (maximum temperature) treatment is subjected to heat treatment to expand or foam. At the same time, a treatment layer 22 having an adhesive force reduced for separation by acting on an elastic modulus improver (FIG. 3) can be used as a method of separating (collecting) the target cut article 31 and the like.

In the above, the heating conditions of the adhesive layer containing a foaming agent having different treatment temperatures may be appropriately determined by the foaming temperature of each foaming agent and the like according to the heat resistance of the supporting base material and the like.
When a plurality of intermediate states can be formed, a part of the intermediate states can be omitted by performing treatment at a higher heating temperature. Note that heat treatment or the like can be performed at an appropriate stage according to the purpose of use.

The foam-peelable sheet of the present invention is subjected to a plurality of measures while keeping the article adhered to the foaming agent-containing adhesive layer,
After the object is achieved, it can be preferably used for various applications that require easy separation (peeling and collection) of the held article. In particular, it is advantageous when measures that favor the cushioning function and the high adhesion state are included as subsequent measures. For example, after initial measures such as printing, transferring, and transporting to other places, measures requiring strong adhesive holding force and impact resistance, such as cutting and polishing, peeling of adhesives, and pressure bonding are required. Is followed.

The foam-peelable sheet of the present invention can be used in an appropriate form. For example, a form that can be continuously introduced into an automatic processing line or the like by arranging it at regular intervals via a carrier tape or the like may be used. Can be. The bonding and holding treatment of the article in the initial state can be performed by an appropriate method such as a simple pressing treatment or a heat pressing treatment according to the adhesive properties of the foaming agent-containing adhesive layer.

The article to be adhered and held in the present invention is optional. Examples include electronic articles such as semiconductor wafers and chips, electric articles such as ceramic capacitors and oscillators, display devices such as liquid crystal cells, and various articles such as thermal heads, solar cells, and printed circuit boards. The plurality of measures to be taken are also arbitrary, such as processing such as polishing, dicing, pattern formation, and assembly, and transport.

Example 1 100 parts of a base polymer composed of acrylic graft rubber (acrylic 20 parts (parts by weight, the same applies hereinafter): MMA) was added to
10 parts of terpene-based tackifying resin, resin 6 having Tg of 80 ° C.
0 parts, sulfurizing agent 0.5 parts, heat-expandable fine particles A (Microsphere F-50D: for heating and foaming at 120 ° C., the same applies hereinafter) 1
5 parts, heat-expandable fine particles B (Microsphere F-80S)
D: for 150 ° C. for heating and foaming, the same applies hereinafter) 30 parts of an adhesive, and 20 parts of an alkylphenol resin are prepared, and a toluene solution of an adhesive is prepared, and the thickness after drying on a 25 μm-thick polyester film is 30 μm. And heated and dried to obtain a foam-peelable sheet.

Example 2 In a toluene solution containing 100 parts of an acrylic copolymer having a weight average molecular weight of 800,000 and 100 parts of butyl acrylate and 5 parts of acrylic acid, 15 parts of heat-expandable fine particles A, 30 parts of heat-expandable fine particles B, and peroxide were added. A foam-peelable sheet was obtained in the same manner as in Example 1 except that an adhesive containing 3 parts of benzoyl was used.

Comparative Example 1 A foamable sheet was obtained in the same manner as in Example 1 except that the thermally expandable fine particles B were not blended.

Comparative Example 2 A foamable sheet was obtained in the same manner as in Example 1 except that the thermally expandable fine particles A were not blended.

Comparative Example 3 A foamable sheet was obtained in the same manner as in Example 1 except that the alkylphenol resin was not used.

Evaluation Test Adhesive Strength The foaming agent-containing adhesive layers in the foam-peelable sheets obtained in the Examples and Comparative Examples were each made of a stainless steel plate (SUS 304 B
Room temperature (adhesion treatment) for A finished surface) and 120 ° C
Alternatively, the adhesive strength after heating at 150 ° C. for 1 minute (1
80 degree peel) was measured based on JISZ0237.

The results are shown in Table 1. In the table,
The layer thickness after each heating expansion of the foaming agent-containing adhesive layer is also shown. The unit of the layer thickness is μm, and the unit of the adhesive force is g / 20 mm.

[Table 1]

[0036]

According to the foam-peelable sheet of the present invention, the adhesive layer containing two or more foaming agents and the elastic modulus improver can be used.
It is possible to stably form at least three stages of adhesive force state from an intermediate state of high adhesive force to an adhesive force reduced state, and to perform a plurality of measures such as processing and transportation without peeling off the bonded and held article, The step of separating and bonding the article and the adhesive layer can be omitted, and ultimately the adhesive force can be sufficiently reduced and the article can be easily separated without damaging the article.
In addition, the intermediate state has a cushioning function due to expansion by the foaming agent, and protects the adhesive holding article from impact force.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a cross-sectional view illustrating an application process of the embodiment.

FIG. 3 is a cross-sectional view illustrating another application process of the embodiment.

[Explanation of symbols]

 1: Supporting base material 2: Foaming agent-containing adhesive layer 21: Foaming agent-containing adhesive layer in an intermediate treatment state 22: Foaming agent-containing adhesive layer in a final treatment state 3: Adhered and held article 31: Cut-processed article

Claims (1)

(57) [Claims] At least one side of a supporting base material contains two or more kinds of foaming agents having different processing temperatures and an elasticity improver for high temperature processing, and heat treatment at different temperatures to achieve an intermediate state of high adhesive strength. A foam-peelable sheet having a foaming agent-containing adhesive layer that forms at least three stages of adhesive force states leading to a reduced adhesive force state.