JP4130509B2 - Adhesive foam - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an adhesive foam comprising a vulcanized foam excellent in expansion ratio and adhesive strength.
[0002]
BACKGROUND OF THE INVENTION
Rubber-based foams are used for indoor products such as household appliances and automobiles as cushioning materials, pad materials, heat insulating materials, waterproofing materials, vibration reducing materials, etc. based on their excellent cushioning properties, compressibility, sealing properties, soundproofing properties, etc. It is widely used in various fields such as outdoor products and buildings such as houses, and there are cases where adhesion treatment is required for practical use.
[0003]
Conventionally, a method of providing a double-sided pressure-sensitive adhesive tape on one side or both sides of a rubber-based foam and bonding it to an adherend through the same has been generally employed for the above-mentioned adhesion treatment. Vulcanized rubber that exhibits tackiness, such as butyl rubber, is also known, but if it is made into a foam, the adhesive strength decreases and the self-supporting adhesive strength is insufficient. It is because it is difficult to express the characteristic as a foam.
[0004]
However, in the adhesion treatment via the double-sided pressure-sensitive adhesive tape, the adhesive layer sinks into the surface layer of the foam, or assists with difficulties such as difficulty in developing an adhesive force between the adhesive layer and the foam. Since the double-sided pressure-sensitive adhesive tape that supports the pressure-sensitive adhesive layer with a base material made of a PET film or a nonwoven fabric is used, there is a problem that the extensibility of the foam is hindered. When the support substrate is not required by providing a thick adhesive layer, the paste (adhesive layer) is easy to flow, and the problem is that the paste protrudes during storage and impairs workability.
[0005]
[Technical Problem of the Invention]
An object of the present invention is to develop a foam that exhibits excellent adhesive strength based on tackiness, while having excellent foaming ratio and excellently maintaining the properties as a foam, and being less prone to paste sticking.
[0006]
[Means for solving problems]
In the present invention, butyl rubber, sulfur vulcanizable liquid rubber, sulfur-based vulcanizing agent and organic foaming agent are at least components, and the use ratio of the butyl rubber / liquid rubber is 95/5 to 50/50 based on the weight ratio. It is an object of the present invention to provide an adhesive foam characterized by comprising a vulcanized foam having adhesiveness of an admixture.
[0007]
【The invention's effect】
According to the present invention, it is possible to obtain a vulcanized foam having excellent foaming ratio and adhesive strength based on the above composition, maintaining excellent properties such as extensibility as a foam, and excellent based on adhesiveness. In addition, it is possible to eliminate the need for the provision of a separate adhesive layer and avoid the problem of glue sticking out and the problem of elongation restriction due to the substrate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The pressure-sensitive adhesive foam according to the present invention contains at least butyl rubber, sulfur vulcanizable liquid rubber, sulfur vulcanizing agent and organic foaming agent, and the use ratio of the butyl rubber / liquid rubber is 95/5 to 50 based on the weight ratio. It is made of a vulcanized foam having an adhesiveness of / 50.
[0009]
As the butyl rubber, any suitable one can be used, and there is no particular limitation. In particular, those having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 40 to 90 are preferably used from the viewpoint of foaming characteristics and adhesiveness of the obtained vulcanized foam.
[0010]
On the other hand, as the liquid rubber, any suitable rubber that can be vulcanized with sulfur can be used. Examples include isoprene, butadiene, styrene / butadiene, styrene / butadiene / styrene, styrene / isoprene / styrene, styrene / ethylene / butadiene, ethylene / propylene / diene, styrene / isoprene / propylene / styrene, and their partial water. Examples thereof include liquid rubber made of additives. Among these, partially hydrogenated isoprene leaving a double bond is preferably used from the viewpoints of foaming ratio and adhesive strength by co-vulcanization with butyl rubber.
[0011]
The use ratio of butyl rubber and liquid rubber is 95/5 to 50/50 based on the weight ratio of butyl rubber / liquid rubber. If the proportion of butyl rubber used exceeds 95, the admixture has poor fluidity and a uniform skin layer is difficult to form during the heat foaming process, making it difficult to form a foam with good adhesion. On the other hand, when the use ratio of butyl rubber is less than 50, it is difficult to form an adhesive foam.
[0012]
The preferred use ratio of butyl rubber / liquid rubber is 90/10 to 60/40 from the viewpoints of foaming ratio and foam formability with excellent adhesive strength. When solid rubber is used instead of liquid rubber, as in the case of butyl rubber rich, the fluidity of the admixture is poor, and a uniform skin layer is not easily formed during the heat foaming process, resulting in good adhesion. It becomes difficult to form a foam.
[0013]
As the vulcanizing agent, sulfur-based compounds such as sulfur and sulfur compounds are used from the viewpoint of the vulcanizability, foamability, and tackiness of the obtained foam, and sulfur can be preferably used. The amount of the sulfur-based vulcanizing agent used is preferably 10 parts by weight or less per 100 parts by weight of the total of butyl rubber and liquid rubber.
[0014]
As an organic foaming agent, a suitable thing can be used and there is no limitation in particular. Examples include fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azo compounds such as azobisisobutyronitrile, azodicarboxylic amide (ADCA), barium azodicarboxylate, and paratoluenesulfonyl. Examples thereof include hydrazine compounds such as hydrazide, diphenylsulfone-3,3′-disulfonylhydrazide, 4,4′-oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide).
[0015]
Also, semicarbazide compounds such as ρ-toluylenesulfonyl semicarbazide and 4,4′-oxybis (benzenesulfonyl semicarbazide), triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole, N, N′— Organic foaming agents such as dinitrosopentamethylenetetramine and N-nitroso compounds such as N, N′-dimethyl-N, N′-dinitrosotephthalamide are also included.
[0016]
The amount of the organic foaming agent used can be determined as appropriate, but in general, from the viewpoint of the physical properties of the foam obtained, particularly the foaming ratio and adhesive strength, 0.1 to 0.1 parts per 100 parts by weight of the total of butyl rubber and liquid rubber. 20 parts by weight, especially 0.5 to 15 parts by weight, especially 1 to 12 parts by weight.
[0017]
Preparation of the admixture is performed as appropriate, for example, by mixing a blended component consisting of at least butyl rubber, sulfur vulcanizable liquid rubber, sulfur vulcanizing agent and organic foaming agent through a kneader such as a kneader or a mixing roll. Can be carried out by mixing in various ways. At that time, a mixing method in which the temperature rises to such an extent that vulcanization proceeds is not preferable.
[0018]
In preparing the admixture, an appropriate compounding agent according to the prior art can be added for the purpose of adjusting viscosity and vulcanizability, and adjusting physical properties such as strength of the resulting foam. By the way, for the purpose of promoting vulcanization, for example, vulcanization accelerators composed of guanidines, thiazoles, sulfenamides, turums, dithiocarbamic acids, xanthogenic acids, aldehyde ammonias, aldehyde amines, thioureas, etc. A vulcanization acceleration aid can be blended. The amount of the vulcanization accelerator used is suitably 0.1 to 10 parts by weight per 100 parts by weight in total of butyl rubber and liquid rubber, but is not limited thereto.
[0019]
For the purpose of promoting foaming, for example, a foaming aid such as urea, salicylic acid or benzoic acid can be blended. The amount of the foaming aid used is suitably 0.1 to 20 parts by weight per 100 parts by weight in total of butyl rubber and liquid rubber, but is not limited thereto.
[0020]
In addition, for the purpose of adjusting physical properties such as strength of the resulting foam, the admixture contains acrylic polymer such as poly (meth) acrylic acid alkyl ester, polyvinyl chloride, polyethylene, polypropylene, ethylene / vinyl acetate copolymer. An appropriate non-rubber thermoplastic polymer such as coalescence, polyvinyl acetate, polyamide, polyester, chlorinated polyethylene, urethane polymer, styrene polymer, silicone polymer, epoxy resin, or the like can also be blended. The amount used is preferably 50% by weight or less of the total amount of butyl rubber and liquid rubber, especially 30% by weight or less, particularly 15% by weight or less, from the viewpoint of maintaining the rubbery properties of the foam.
[0021]
In addition, for the purpose of adjusting the processability or moldability of the admixture, for example, organic acids such as phthalic anhydride, benzoic acid and salicylic acid, N-nitroso-diphenylamine and N-nitroso-phenyl-β-naphthylamine are used. A vulcanization retarder composed of amines or the like can be blended to retard vulcanization as opposed to the vulcanization accelerator described above.
[0022]
In addition, for the purpose of controlling moldability, the admixture contains, for example, paraffins such as chlorinated paraffin, waxes, naphthenes, aromas, asphalts, dry oils such as linseed oil, animal and vegetable oils, petroleum It is also possible to add a softening agent comprising a series of oils, various low-volume polymers, phthalic acid esters or phosphoric acid esters, stearic acid or its esters, alkyl sulfonic acid esters or tackifiers. Note that stearic acid and its esters are useful as a lubricant and the like, and therefore, examples of components in which various lubricants can be blended.
[0023]
In addition, the admixture contains fillers such as talc and calcium carbonate, clay and mica powder, aluminum hydroxide and magnesium hydroxide, zinc white and bentonite, carbon black and silica, alumina and aluminum silicate, acetylene black and aluminum powder. In addition, an appropriate compounding agent such as a plasticizer, an anti-aging agent, an antioxidant, a pigment, a colorant, or an antifungal agent can be added as necessary. The zinc white is also useful as a stabilizer, and carbon black is useful as a reinforcing agent. Therefore, examples of components in which various stabilizers and reinforcing agents can be blended are listed.
[0024]
Each component consisting of the above-mentioned butyl rubber, sulfur vulcanizable liquid rubber, sulfur vulcanizing agent, organic foaming agent, and other compounding agents as needed is one or more in the preparation of the admixture. Can be used.
[0025]
The pressure-sensitive adhesive foam according to the present invention can be formed by heating the above-mentioned admixture and subjecting it to a vulcanization foaming treatment. In forming the adhesive foam, the admixture is formed into a predetermined form such as a sheet as necessary. The molded body can be heat-treated to obtain a vulcanized foam. In that case, the molded body may be molded into an arbitrary form by an appropriate method, and the form is not particularly limited.
[0026]
Accordingly, the admixture may be formed into a sheet by an appropriate method such as a mixing roll, a calender roll, or extrusion molding, or may be an appropriate method such as injection molding or press molding via a predetermined mold. What was shape | molded in the predetermined | prescribed form which has an unevenness | corrugation etc. may be used.
[0027]
In the above, in the formation of a foam having an uneven shape, an unvulcanized sheet is placed on a mold having unevenness and heated, and the mixture forming the unvulcanized sheet flows into the unevenness of the mold to flow in A method of vulcanizing and foaming can also be adopted. Such a method has an advantage that the concavo-convex shape can be accurately formed even in the case of a mold having a complex and deep concavo-convex structure.
[0028]
Therefore, the size of the molded body is arbitrary, and can be appropriately determined according to the form of the target vulcanized foam. In the case of a sheet or the like, the thickness is generally 100 mm or less, in particular, 1 μm to 80 mm, particularly 10 μm to 50 mm.
[0029]
The vulcanization foaming treatment described above can be performed under appropriate conditions according to the prior art depending on the vulcanization start temperature, foaming temperature, and the like using the vulcanizing agent and the foaming agent used. A typical vulcanization foaming temperature is 450 ° C. or less, especially 120 to 350 ° C., particularly 150 to 300 ° C. Typically, such vulcanization foaming treatment softens the admixture and expands the foaming agent to form a foamed structure while vulcanization proceeds to form a vulcanized foam having the desired tackiness.
[0030]
In the above, the foaming treatment and the vulcanization treatment can be performed under different temperature conditions, and appropriate treatment conditions can be taken. The vulcanization foaming treatment can also be performed under pressure for the purpose of adjusting the foaming ratio. The pressurizing condition can be based on the conventional one.
[0031]
The expansion ratio of the vulcanized foam to be formed can be appropriately determined according to the purpose of use. In the present invention, from the viewpoint of foaming characteristics such as extensibility and compressibility, it is 0.7 g / cm ³ or less, especially 0.65 g / cm ³ or less, particularly 0.5 to 0. The expansion ratio is preferably 6 g / cm ³ .
[0032]
The adhesive strength based on the tackiness of the vulcanized foam can also be appropriately determined according to the purpose of use, etc., but in the present invention, it is 30 g / 25 mm or more based on 180 degree peel to the stainless steel plate, especially 40 g / 25 mm or more. In particular, the adhesive strength of 45 g / 25 mm or more, such as the self-supporting property when adhered to the adherend, the adhesive support strength of the adherend when used as a double-sided pressure-sensitive adhesive sheet, etc. More preferred.
[0033]
The foaming ratio can be controlled by the blending amount of the foaming agent described above, the treatment time and temperature of vulcanization foaming, and the like. In addition, by adjusting the expansion ratio, etc., the obtained vulcanized foam can be controlled independently or continuously, a foamed structure such as a mixture thereof, adhesive force based on tackiness, and the like.
[0034]
The adhesive foam according to the present invention can be used in various conventional applications such as cushioning materials, pad materials, sealing materials such as heat insulating materials and waterproofing, and vibration reducing materials such as soundproofing and damping.
[0035]
【Example】
Example 1
80 parts (parts by weight) of butyl rubber, 20 parts of partially hydrogenated liquid isoprene rubber, 2 parts of sulfur, 2 parts of tetramethylthiuram disulfide, 1 part of 2-mercaptobenzothiazole, 6 parts of ADCA, 6 parts of urea foaming aid, 50 parts of heavy calcium carbonate, 30 parts of carbon, 20 parts of paraffinic oil, 5 parts of zinc oxide and 1 part of powdered stearic acid are kneaded with a pressure kneader to obtain an admixture, which is 3 mm thick with a press molding machine. A pressure-sensitive adhesive foam was obtained by vulcanizing and foaming at 180 ° C. for 10 minutes to obtain a vulcanized foam sheet.
[0036]
Example 2
An adhesive foam was obtained according to Example 1, except that the amount of butyl rubber used was 60 parts and the amount of partially hydrogenated liquid isoprene rubber used was 40 parts.
[0037]
Example 3
An adhesive foam was obtained according to Example 1 except that the amount of butyl rubber used was 90 parts and the amount of partially hydrogenated liquid isoprene rubber used was 10 parts.
[0038]
Comparative Example 1
An adhesive foam was obtained in the same manner as in Example 1 except that the amount of butyl rubber used was 100 parts and the partially hydrogenated liquid isoprene rubber was not used.
[0039]
Comparative Example 2
A foam was obtained in the same manner as in Example 1 except that the amount of butyl rubber used was 40 parts and the amount of partially hydrogenated liquid isoprene rubber used was 60 parts.
[0040]
For the (adhesive) foams obtained in the evaluation test examples and comparative examples, the apparent density was examined, and the adhesive strength based on 180 ° peel (23 ° C., 65% RH, peeling speed 300 mm / min) to the stainless steel plate was examined. .
[0041]
The results are shown in the following table.

Claims (2)

Adhesion of admixture comprising at least butyl rubber, sulfur vulcanizable liquid rubber, sulfur vulcanizing agent and organic foaming agent, and the use ratio of the butyl rubber / liquid rubber is 95/5 to 50/50 based on the weight ratio. A pressure-sensitive adhesive foam comprising a vulcanized foam having properties. In claim 1, the adhesive foam apparent density is 0.5~ 0.7g / cm ^3.