JPS63186791A - Foamable pressure-sensitive member - Google Patents

Abstract

PURPOSE:To made it possible to regulate as desired the adhesion of a pressure- sensitive adhesive layer and the foamability of a foaming agent-contg. layer, by separating a foamable pressure-sensitive member contg. a foaming agent into two distinct layers. CONSTITUTION:A foaming agent-contg. layer 2 which contains a foaming agent (e.g. propane) and is expandable by foaming is formed on a substrate 3 such as paper or cloth. Then, a pressure-sensitive adhesive layer 1 (e.g., an acrylic pressure-sensitive adhesive layer) is formed on this layer 2. Thus, there is obtd. a desired foamable pressure-sensitive member. Since the foaming agent-contg. layer 2 and the pressure-sensitive adhesive layer 1 are separated from each other the obtd. member is free from a reduction in the adhered area and changes in the foaming and adhesion properties with time which are attributed to the mixing of the foaming agent with the pressure-sensitive adhesive layer. Freedom in designing increases for each of the layers 1 and 2 and it becomes possible to prepare a member of high foaming ratio or high adhesive strength.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention has a foaming agent-containing layer between a support base material and a pressure-sensitive adhesive layer, and the foaming treatment facilitates peeling. On the contrary, it relates to a foamed adhesive member that increases adhesive strength.

PRIOR TECHNOLOGIES AND PROBLEMS Hitherto, adhesive sheets have been known in which a pressure-sensitive adhesive layer contains a foaming agent (Japanese Patent Publication No. 13878/1983, Japanese Patent Publication No. 51-24534, Japanese Patent Application Laid-Open No. 61468/1982)
No. 56-61469, No. 60-2526
Publication No. 81, etc.). The purpose of these is to foam the foaming agent through heat treatment to reduce the adhesion area to the adherend, thereby facilitating the peeling of the pressure-sensitive adhesive sheet from the adherend.

However, since the foaming agent is contained in the pressure-sensitive adhesive layer, each element may inhibit the functions of other elements, such as reducing the adhesion area of the contact layer. There was a problem in that the pressure-sensitive adhesive layers mutually denatured and the foaming strength and adhesive strength decreased over time. In addition, it was difficult to adjust the balance between foaming ratio and adhesive strength, making it difficult to prepare products with desired characteristics. However, its versatility is poor and its use is limited to a narrow range.

Means for Solving the Problems The present invention overcomes the above problems by forming the foaming agent-containing layer and the pressure-sensitive adhesive layer into separate layers.

That is, the present invention provides a pressure-sensitive adhesive member such as a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is provided on a support base material, and a foaming agent is contained between the support base material and the pressure-sensitive adhesive layer. The present invention provides a foam adhesive member characterized by having a layer that expands upon treatment.

Effect By separating the foaming agent-containing layer and the pressure-sensitive adhesive layer, it is possible to avoid a decrease in the bonding area due to mixing of the foaming agent and the pressure-sensitive adhesive layer, as well as changes in foaming properties and adhesive properties over time. be able to. In addition, the degree of freedom in designing each layer is increased, as the adhesive properties of the pressure-sensitive adhesive layer and the foaming properties of the foaming agent-containing layer can be set appropriately, making it possible to create high expansion ratio types and high adhesive strength types. As a result, the versatility of the foam adhesive member can be increased.

Examples of Constituent Elements of the Invention The foamed adhesive member of the present invention has a foaming agent-containing layer between the support base material and the pressure-sensitive adhesive layer.

Typical examples of this form include, for example, as shown in FIG. 1, a supporting base material 3 has a foaming agent-containing layer 2 on one side and a pressure-sensitive adhesive layer 1 on the outside thereof, or as shown in FIG. As shown in FIG. Foaming agent-containing layer 2
Examples include those that have it only on one side.

There are no particular limitations on the supporting base material to be used. Among these, thin materials such as tapes and sheets with a thickness of 10 to 1 mm are generally used, such as paper, laminated paper, cloth, laminated cloth, plastic film, metal foil, etc.

There are no particular limitations on the form of the foaming agent-containing layer or the method for forming it. The blowing agent-containing layer may also be in direct contact with the supporting substrate or the pressure-sensitive adhesive layer, with an appropriate layer interposed between them as necessary, such as a barrier layer for blown gas. Typical forms of the blowing agent-containing layer include a blowing agent-containing film layer, a blowing agent-containing fiber mat layer, and a sandwich structure layer in which a blowing agent is interposed between films. Formation methods include pasting a ready-made foaming agent-containing film, or sequentially forming them.Among others, a foaming agent is added to an appropriate binder liquid and the film is coated and solidified. A method of sequentially forming a blowing agent-containing layer is preferable in terms of formation efficiency and thinning of the layer.

Foaming agents that can be used bimonthly include inorganic foaming agents such as ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides, azobisisobutyronitrile,
Azo compounds such as azodicarbonamide and barium azodicarboxylate, toluenesulfonyl hydrazide,
diphenylsulfone-3,3'-disulfohydrazine,
4゜4″-oxybis(benzenesulfohydrazide),
Hydrazine compounds such as allylbis(sulfohydrazide), ρ-tolylenesulfonyl semicarbazide, 4.4
'-oxybis(benzenesulfonyl semicarbazide)
semicarbazide compounds such as, 5-morpholyl-1,2
, 3,4-thiatriazole and other triazole compounds, N,N'-dinitrosopentamethylenetetramine, N
, N'-dimethyl-N, N'-dinitrosoterephthalamide and other organic compounds, as well as low-boiling substances such as propane, butane, petroleum ether, etc. Examples include those that are publicly known. Note that microencapsulated foaming agents are preferably used from the viewpoint of ease of handling and dispersibility in the foaming agent-containing layer.

As a microencapsulated blowing agent, vinylidene chloride
Examples include thermally expandable hollow bodies in which volatile or easily vaporizable substances such as isobutane and inorganic sodium bicarbonate are encapsulated using a shell-forming material such as acrylonitrile copolymer.

On the other hand, as a binder, it has an appropriate foaming agent retention ability,
It is appropriate to use a material that allows the foaming agent to foam by heating.

Examples include acrylic (co)polymers, acrylonitrile (co)polymers, polyester resins, polyolefins such as polyethylene and polymers [cobylene], vinyl (co)polymers such as polyvinyl chloride and polystyrene, polyamide resins, etc. Examples include thermoplastic resins, crosslinked resins such as isocyanate resins, and melamine resins, which are generally used to form films and adhesives, such as hot melt types, solution types, and water-based types. .

The layer thickness, expansion ratio, etc. of the foaming agent-containing layer are appropriately determined depending on the intended use of the foamed adhesive member. In general, the layer thickness is 5 to 2000 μm, preferably 10 to 500 μm, and the foaming ratio is 2 to 200 μm, and the foaming agent-containing layer has a layer thickness of 2 to 500 μm.
For example, it increases by a factor of 1000. In addition, the desired foaming agent-containing layer is set so that the foaming process is completed by heating at 50 to 200°C for about 5 minutes or less, but the foaming state is such that the foaming agent-containing layer is simply expanded. It may also be one in which the gas generated as it expands is ejected from the foaming agent-containing layer or even from the pressure-sensitive adhesive layer.

In the present invention, a known pressure-sensitive adhesive can be used, and it may be a type that hardens by heat treatment or ultraviolet treatment, etc., depending on the purpose of use of the foam adhesive member. It is determined. Typical examples of pressure-sensitive adhesives used include rubber-based pressure-sensitive adhesives made of natural rubber, various synthetic rubbers, etc., alkyl ester polymers such as acrylic acid or methacrylic acid, or alkyl ester polymers such as acrylic acid or methacrylic acid. 50-99.5% by weight
and other unsaturated monomers copolymerizable with this about 50 to 0.5
Acrylic polymers made of copolymers with % by weight, etc.
Its weight average molecular weight is s, ooo ~ 3.000.000
Examples include acrylic pressure-sensitive adhesives in which a base polymer is a polyisocyanate compound, a crosslinking agent such as an alkyl etherified melamine compound, etc., as required. In addition, when a crosslinking agent is used in combination, the amount of the crosslinking agent is approximately 0.1 to 1 liter per 100 parts by weight of the base polymer.
O parts by weight is common.

The thickness of the pressure-sensitive adhesive layer is also appropriately determined depending on the intended use of the foamed adhesive member. Generally, it is 1 to 500 μm.

The foam-type adhesive member of the present invention can be made by appropriately adjusting the foaming properties of the foaming agent-containing layer, the thickness of the pressure-sensitive adhesive layer, and the hardness and cohesive force of the pressure-sensitive adhesive layer. It can be prepared as an easy-peel type that allows the adherend to be easily peeled off, or that the adherend peels off naturally due to its own weight, or it can be prepared as a type that does not change its adhesive strength or that foams as opposed to an easy-peel type. It is also possible to prepare a type that increases the adhesion force to the adherend by increasing the pressure bonding force. The latter type, in which the adhesive strength is increased by foaming treatment, cannot be achieved with conventional foaming agents contained in the pressure-sensitive adhesive layer. Furthermore, by changing the foaming treatment conditions, the same composition can be used as an easily peelable type, a type in which the adhesive strength does not change, or a type in which the adhesive strength increases.

Generally, an advantageous configuration for an easy-peel type is to make the pressure-sensitive adhesive layer thin or to make it difficult to flow.
Pressure-sensitivity can be achieved through foaming treatment (simple expansion or expansion accompanied by gas jets), either by curing with heat or ultraviolet light, etc., resulting in a decrease in adhesive strength, or by increasing the foaming power of the foaming agent-containing layer. The purpose is to create a structure in which the surface of the adhesive layer is likely to be uneven, or to be in a crater-like or porous state, and the adhesive area to the adherend is likely to be reduced. From this point of view, it is preferable to provide a pressure-sensitive adhesive layer directly above the foaming agent-containing layer.

The above-mentioned easily peelable foam adhesive member is suitable for temporary fixing, for example, when a fragile item is subjected to processing that involves cutting or the like.

On the other hand, advantageous configurations for the type where the adhesive strength does not change or the type where the adhesive strength increases are as follows: the pressure-sensitive adhesive layer is made thicker or more fluid, or the foaming agent-containing layer is simply foamed. Contrary to the case of the above-mentioned easy-peel type, the adhesive area to the adherend is reduced by the foaming process, and the expansion due to foaming reduces the pressure bonding force to the adherend. From this point of view, the expansion of the foaming agent-containing layer due to foaming causes a shape change to the pressure-sensitive adhesive layer. It is preferable to interpose it between the foaming agent-containing layer and the pressure-sensitive adhesive layer.

The above types, especially those having pressure-sensitive adhesive layers on both sides, are suitable as joining members for adherends, repair members, etc. That is, a foamed adhesive member is attached to one of the adherends arranged in a gap, and it is heated and foamed to expand (increase in thickness).
A foamed adhesive member is attached to the bonding member to be bonded to another adherend, or to the cracked part of the adherend, and then heated and foamed while being pressed with the cover material to form the cracked part. It can be preferably used as a repair member when filling.

Effects of the Invention According to the present invention, since the pressure-sensitive adhesive layer and the foaming agent-containing layer are separated, a reduction in the adhesive area of the pressure-sensitive adhesive layer due to the mixing of the foaming agent can be avoided, and denaturation due to mutual influence can be avoided. Can be prevented or suppressed. Further, the characteristic settings for each layer can be selected from a wide range. As a result, the adhesive properties and foaming properties are excellent in maintaining the initial state, and the adhesive properties of pressure-sensitive adhesives allow for high-adhesion and low-adhesion types, as well as high-foaming and low-foaming types based on the amount of foaming agent. Alternatively, it is possible to prepare products having various characteristics such as an easy-peel type and a type that maintains or increases adhesive strength based on the overall structure, and is excellent in versatility.

Examples Example 1 100 parts (parts by weight, the same shall apply hereinafter) of polymethyl methacrylate having a molecular weight of approximately 100,000 and Microsphere-F-30D were placed on one side of a support base material made of a 100 μm thick polyester film whose surface was subjected to corona discharge treatment. (Product name, manufactured by Matsumoto Yushi Co., Ltd.) A mixed solution containing 30 parts of polyisocyanate resin and 10 parts of polyisocyanate resin was coated and dried to form a foaming agent-containing layer with a thickness of 30 cm, and then a layer containing 100 butyl acrylate was applied on top of the foaming agent-containing layer. A copolymer consisting of 1 part and 2 parts of acrylic acid has a weight average molecular weight of about 8.
A pressure-sensitive adhesive consisting of 100 parts of 100,000 parts) and 2 parts of a polyisocyanate-based crosslinking agent was applied and dried to form a pressure-sensitive adhesive layer with a thickness of 5 μm to obtain a foamed adhesive member.

Example 2 A foamed adhesive member was obtained according to Example 1, except that polystyrene was used instead of polymethyl methacrylate as the binder.

Example 3 A foamed adhesive member was obtained according to Example 1, except that 60 parts of paratoluenesulfonyl hydrazide was used in place of Microsphere-F-30D as a foaming agent.

Example 4 Polystyrene was used instead of polymethyl methacrylate as a binder and Microsphere-F-3 was used as a blowing agent.
Paratoluenesulfonyl hydrazide 60 instead of 0D
A foamed adhesive member was obtained in the same manner as in Example 1, except that the following procedure was used:

Comparative Example 1 Instead of forming a foaming agent-containing layer and a pressure-sensitive adhesive layer into separate layers, 100 parts of a copolymer (weight average molecular weight approximately 800,000) consisting of 100 parts of butyl acrylate and 2 parts of acrylic acid and polyisocyanate were used. 2 parts of crosslinking agent and microsphere-F-3
Supports a 30 μm thick foaming agent-containing pressure-sensitive adhesive layer made of a foaming agent-containing pressure-sensitive adhesive prepared by mixing 30 parts of OD, 5 parts of ammonia water (25% A), and 10 parts of water using a solvent. A foamed adhesive member was obtained in the same manner as in Example 1 except that it was directly provided on the base material.

Comparative Example 2 A foamed adhesive member was obtained according to Comparative Example 1, except that 60 parts of para-toluenesulfonyl hydrazide was used instead of Microsphere-F-30D as a foaming agent.

Evaluation test The adhesive strength of the foamed adhesive members obtained in the above examples and comparative examples to a stainless steel plate in the initial state or after being left indoors for 3 months was measured, and the adhesive strength of the pressure-sensitive adhesive layer or the foaming agent-mixed pressure-sensitive adhesive was measured. A layer of size 1.5 consisting of a laminate of unsintered ceramic sheets of size 100 mm x 100 mm pressed and fixed to the layer with a force of 100 kg / c + J
With the cut pieces measuring +nm x 2.5 mm square and weighing 5 mg facing downward, heat and foam the foamed adhesive member at 100°C, 130°C or 160°C until all the cut pieces naturally peel off and fall. The average time was measured.

The results are shown in Table 1.

Table 1 Example 5 Polymethyl methacrylate 10 having a molecular weight of about 100,000 was coated on one side of a supporting base material made of paper with a thickness of 50 μm with a small amount of impregnating agent.
A foaming agent-containing layer with a thickness of 30 μm was formed by coating and drying a mixed solution containing 0 parts of Microsphere-F-30DlS and 10 parts of a polyisocyanate resin, and then a layer containing a foaming agent with a thickness of 30 μm was formed on the foaming agent-containing layer and on the other side of the supporting base material. A pressure-sensitive adhesive consisting of 100 parts of a copolymer (with a weight average molecular weight of approximately 800,000) consisting of 100 parts of butyl acrylate and 7 parts of acrylic acid and 3 parts of a polyisocyanate crosslinking agent was applied and dried to a thickness of 20 μm. A pressure-sensitive adhesive layer was provided to obtain a foamed adhesive member with a thickness of 120 μm,
Separators were attached to both sides.

Example 6 A foamed adhesive member having a thickness of 150 parts m was obtained according to Example 5 except that foaming agent-containing layers were provided on both sides, and separators were attached to both sides of the foamed adhesive member.

Comparative Example 3 Instead of forming separate layers of a foaming agent-containing layer and a pressure-sensitive adhesive layer, a copolymer (weight average molecular weight of about 500,000) 101 consisting of 100 parts of butyl acrylate and 7 parts of acrylic acid and a polyisocyanate-based 3 parts of crosslinking agent and microsphere-F-30
A foaming agent-containing pressure-sensitive adhesive layer having a thickness of 50 um made of a foaming agent-containing pressure-sensitive adhesive mixed and prepared using 15 parts of D was directly provided on the supporting substrate, but the same procedure as in Example 5 was followed to obtain a 120-μm-thick foaming agent-containing pressure-sensitive adhesive layer.
A foamed adhesive member having a diameter of μm was obtained, and separators were attached to both sides of the adhesive member.

Comparative Example 4 A foamed adhesive member with a thickness of 150 μI was obtained according to Comparative Example 3, except that a 50 μm thick foaming agent-mixed pressure-sensitive adhesive layer was provided on both sides of the support base material, and separators were attached to both sides of the foamed adhesive member. did.

One separator was peeled off and the foamed adhesive member obtained in Evaluation Test Examples 5 and 6 or Comparative Examples 3 and 4 was attached to the end face of an aluminum rod with a length of 20 cm + m and a cross-sectional area of 10 + maXlonua, and then the other separator was also attached. Peel it off and apply 300-
The end surfaces of separate aluminum rods of the same size are placed opposite each other with a gap and fixed, and in this state hot air (1
A heat foaming treatment was performed by spraying at 60° C. for 3 minutes, and the adhesive properties of the resulting joined body of aluminum rods were examined.

The results are shown in Table 2. The tensile strength was measured by fixing one end of the joined body and pulling the other end at a speed of 300 mm/min. To check for misalignment, fix the joined body horizontally at one end, hang a weight of 1 kg at a location loc from the other end, apply a bending moment, and after 1 hour or 1 hour.
The deviation distance between the horizontal line and the aluminum rod at the hanging point of the weight was measured.

Table 2

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are cross-sectional views showing structural examples of the foamed adhesive member of the present invention. 1: FJ pourable adhesive layer 2: Foaming agent-containing layer 3: Support base material

Claims (1)

[Claims] 1. In an adhesive member such as an adhesive sheet comprising a support base material and a pressure-sensitive adhesive layer, a foaming agent is contained between the support base material and the pressure-sensitive adhesive layer. A foam-type adhesive member characterized by having a layer that expands by foaming treatment. 2. The foamed adhesive member according to claim 1, which is of a type that can be easily peeled off by foaming treatment. 3. The foamed adhesive member according to claim 1, which is of a type whose adhesive strength is increased by foaming treatment. 4. The foamed adhesive member according to claim 1, wherein the foaming agent is microencapsulated.