MX2008008272A - Closed cell foam rubber sheet, laminate, and waterproof/watertigh t sealing material using the sheet or lamiante. - Google Patents

Abstract

Disclosed is a high-performance foam structure which comprises a foam structure having closed cells therein and, when used as a waterproof sealing material or the like, shows excellent interface adhesion to a material to be sealed (i.e., a structural element to be imparted with a waterproof property) even when used for a long period. Also disclosed is a high-performance waterproof/watertight sealing material using the foam structure. A closed cell foam rubber sheet can be produced by subjecting a foaming raw material comprising mainly a rubbery resin to crosslinking treatment or foaming treatment, and has an apparent density of 30 to 100 kg/m³ as measured in accordance with JIS K7222 and a compressive permanent strain of 60% or less as measured in accordance with JIS K6262 under the conditions of 70Ë¿C and 24 hours.

Description

ALVEOLAR RUBBER SHEET CLOSED CELL. LAMINATE, AND WATERPROOF / HERMETIC OBTURATION MATERIAL MADE OF LEAF OR LAMINATE TECHNICAL FIELD The present invention relates to closed cell foamed rubber sheets, to laminates, and to impermeable / hermetic sealing materials made from sheets or laminates, and more particularly to closed cell foamed rubber sheets and laminates that are obtained when applying interlacing treatment and foaming treatment to a foamable raw material composition composed mainly of a rubber-based resin and which can be suitably used as sealing materials in various fields such as architecture, construction, electrical engineering, electronics and vehicles, and materials waterproof / hermetic sheets or laminates.

BACKGROUND OF THE INVENTION Today, foams are widely used as sealing materials in various fields such as architecture, construction, electrical engineering, electronics and vehicles. Examples of such foams used as sealing materials include thermoplastic resin foams made of polyethylene-based resin, polypropylene-based resin or the like, and rubber foams made of synthetic rubber or natural rubber. Among the sealing materials, the waterproof / hermetic sealing materials are articles which are used to fill openings in various structures such as vehicles, architectural / construction products, and electric light applications and to prevent water from entering. In said types of waterproof / hermetic sealing materials, a sealing material made of a foam is arranged in a compressed state around a portion where the water must be interrupted. It fills an opening between itself and an interface for its repulsive charges to prevent water from entering. In this case, when the foam, which is a sealing material, is of low compression flexibility, a repulsive force generated by the foam that recovers its shape from the compressed state causes problems such as deformation of an element to be sealed or enlarged. the opening to be blocked due to the deformation of the element to be sealed. As a result, the performance of the seal is poor and it may be impossible to interrupt the passage of water. The compression flexibility of the foams has been improved by changing the cells in a foam to open the cells by breaking them by certain means such as the application of pressure. However, when the cells are changed to open cells, a new problem, i.e., decrease in waterproof property, will arise although the compressive flexibility of the foam is markedly improved. That is, when a sealing material made from a foam having an open cell structure is used, although a sealing material thicker than the opening in a portion to be sealed is needed, a perfect impervious property can not be expected; for example, the initial sealing property is insufficient. Generally, rubber foams and the like have superior damping properties and are therefore useful for applications such as damping materials and filler material. In comparison between closed cells and open cells in a foamed structure, the former has a structure having separate cells in a spherical reticular shape by divisions and the latter having a structure where the exit orifices interconnecting adjacent cells are formed into divisions. The latter can be dynamically deformed more easily. However, although open cells are not expected to have much impermeable action, closed cells can be expected to have an impermeable action due to cell divisions. It can be expected that a foamed structure that has closed cells and open cells has ease in filling work in complex openings caused by easy deformability due to the cells open and impervious property due to closed cells. Therefore, it is assumed to be suitable as a fixed waterproof sealing material for use by filling in complex openings. For example, a fixed form sealing material has been proposed in which a foamed skin is swollen by water absorption by forming it from a foamed structure having closed cells and open cells and adjusting the number of cells by a length of 1 cm to eight or more (see, for example, Patent Document 1). During the use of a foamed structure having closed cells and open cells as an impermeable sealing material, however, there is a problem as follows. The repulsive force as a foamed structure relaxes with time and, in association with this, the contact pressure at the interface between the surface of the foamed structure and the structure of the element to be sealed (a structural element to which it has to be sealed). apply impermeable property), decreases, resulting in the occurrence of water leaks along the interface. As a result, the foamed structure does not effectively work as a waterproof sealing material. Therefore, there is a strong demand for high performance foamed structures that are formed from a foamed structure that has closed cells to exert waterproof performance and that maintains excellent interfacial adhesion without relieving repulsive loads such as a foamed structure even when used during a lot time, and for waterproof / airtight sealing materials made from the structures. Patent Document 1: JP-A 09-111899.

BRIEF DESCRIPTION OF THE INVENTION Problems to be Resolved by the Invention In view of the above-mentioned problems with conventional technologies, an object of the present invention is to provide a high performance closed-cell alveolar rubber sheet comprising a foamed structure having closed cells and exhibiting excellent interfacial adhesion to an element to be sealed (a structural element to which the waterproof property will be applied) even when used as a waterproof sealant material for a long time, and a high performance waterproof / hermetic obturator material made from the sheet.

Means for solving problems As a result of intensive studies to achieve the objective, the present inventors found that when bulk density and compression deformation of a closed cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin for the interlacing treatment and foaming treatment are adjusted in intervals Specifically, the sheet exhibits excellent interfacial adhesion to an element to be sealed (a structural element to which the waterproof property must be applied) over a long period of time when used as a waterproof sealant material although it develops low repulsion (repulsive load). low), and therefore overcomes the impervious property. Through additional investigations, they have achieved the present invention. That is, the closed-cell alveolar rubber sheet of the present invention is characterized in that it is obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin for interlacing treatment and foaming treatment and having a bulk density from 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262.

Effect of the invention The use of the closed-cell alveolar rubber sheet of the present invention can provide an excellent waterproof / hermetic sealing material because the adjustment of the bulk density and the compression deformation at specific intervals is effective since excellent interfacial adhesion between a waterproof / hermetic obturator material made from alveolar cell rubber sheet closed and a structural element to which the impermeable property is to be applied is obtained, an excellent waterproof property is maintained for a long period of time, and reliability can be improved. When the entanglement treatment is physical entanglement by ionization radiation or chemical entanglement using an organic peroxide or a sulfur compound, an effect where a closed cell foamed rubber sheet with desired physical properties can be easily produced is obtained because the interlacing treatment is specified. By stipulating the rate of dimensional change upon heating, an excellent waterproof / hermetic sealing material in dimensional stability can be provided. In addition, the addition of an organic peroxide having a half-life temperature one minute higher than the decomposition temperature of a foaming agent produces an effect where the dimensional stability is improved by subjecting the closed-cell alveolar rubber sheet during or after foam molding. When the gel fraction of the closed-cell alveolar rubber sheet is specified, an effect is obtained since a closed-cell foamed rubber sheet having desired physical properties can be easily produced. When the rubber-based resin is nitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR), rubber butyl (II R) or chloroprene rubber (CR), an effect is obtained since the adhesion to a structural element to which the impervious property will be applied is further improved and the impervious property thus improved. When the sheet has a 50% compression load as measured in accordance with JIS K6767 of 60 kPa or less, an effect is obtained since it exhibits excellent waterproof property over a long period of time although it develops low repulsion. In the case of the closed cell alveolar rubber sheet, the peel strength as measured according to JIS K6850 is within a specific range, an effect is obtained since the interfacial adhesion to a structural element to which it will be applied the impervious property is improved and the impervious property in this way is improved. When the foamable raw material composition contains a crystalline resin having a melting point of 25 ° C or higher or a high softening point having a softening point of 25 ° C or higher, a crystalline region of the resin Crystalline or a vitreous region of the high softening point resin does not contract and has a modulus of elasticity high enough that it deforms very little. Therefore, the crystalline resin or the high softening point resin is made to enter between the molecular chains of the rubber-based resin to prevent the rubber-based resin from contracting and the dimensional stability of the resin.

Closed cell alveolar rubber sheet can be improved in this way. When the resin layer is integrally laminated on one side or both sides of the foamable raw material composition prior to foaming the foamable raw material composition or during the molding of the foamable raw material composition, an effect is obtained since the Production variance can be reduced because the measurement of the time of the formation of the resin layer is specified. When the laminate has an acrylic-based or rubber-based pressure-sensitive adhesive layer, an effect is obtained since, during use as an impermeable / hermetic sealing material, the interfacial adhesion between the impermeable / hermetic sealing material and a structural element to which an impervious property will be applied, is improved and the impervious property thus improved. When the pressure sensitive adhesive layer in the laminate is formed of a pressure sensitive adhesive based on polyurethane produced by reacting a raw material comprising a polyol and a polyisocyanate, an effect is obtained since the adhesion and the removal capacity can be imparted, and the waterproof property and the workability can be made compatible. Further, when in the laminate the foamed layer is laminated integrally on one side or both sides of the closed cell foamed rubber sheet or the laminate, an effect is obtained where the flexural rigidity of the laminate is increased and the workability thereof can be to get better.

When the closed cell foamed rubber sheet or the laminate is used as an impermeable / hermetic sealing material, an effect is obtained as it exhibits superior interfacial adhesion with a structural element to which the waterproof property will be applied and a superior waterproof property during a long period of time, and reliability can be improved. Therefore, the present invention can provide closed cell foamed rubber sheets and high performance laminates which can be suitably used as sealing materials in various fields such as architecture, construction, electrical engineering, electronics and vehicles, and sealing materials waterproof / hermetic made from sheets or laminates.

DETAILED DESCRIPTION OF THE INVENTION The following is a detailed description about closed-cell and laminated foamed rubber sheets of the present invention and impermeable / hermetic sealing materials made from sheets or laminates. The closed-cell alveolar rubber sheet of the present invention is characterized in that it is obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and because it has an apparent density of 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262. The closed cell foamed rubber sheet (hereinafter also referred to as the "foamed sheet") of the present invention is obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to crosslinking treatment. and foaming treatment. Only closed cells are required and they can have open cells and closed cells. From the point of view of impervious property, it is desirable that the alveolar rubber sheet have a closed cell ratio as high as possible. The ratio is preferably 80 to 100% or more, and more preferably 85 to 100%. The closed cell ratio of an alveolar rubber sheet refers to a measurement determined in the following procedure. First, a specimen that is in a square shape that measures 5 cm in length on each side and uniform in thickness is cut from a closed cell alveolar rubber sheet. Then, the thickness of the specimen is measured and the apparent volume of specimen Vi is calculated. In addition, the weight of the specimen W-i is measured. Subsequently, the apparent volume occupied by V2 cells is calculated based on the following formula. The density of the resin constituting the specimen is assumed to be 1 g / cm3.

The apparent volume occupied by the cells V2 = \ - Wi. Subsequently, the specimen is wetted in distilled water at 23 ° C at a depth of 100 mm from the water surface and a pressure of 15 kPa is applied to the specimen for 3 minutes. Then, the specimen is taken from the water and the water on the surface of the specimen is removed, this is followed by the measurement of the weight of specimen W2. The open cell ratio F-i and the closed cell ratio F2 are calculated based on the following formulas. Open cell ratio F (%) = 100 x (W2- W -,) / V2 Closed cell ratio F2 (%) = 100 - Fi The closed cell alveolar rubber sheet is required to have a bulk density of 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262. If a sheet of alveolar rubber has a bulk density of less than 30 kg / m3, the sheet of alveolar rubber is somewhat fragile that can not maintain its strength. Therefore, in use as an impermeable / hermetic sealing material, it can keep its property impermeable for a long period of time. Conversely, if an alveolar rubber sheet has a bulk density of more than 100 kg / m 3, the alveolar rubber sheet is hard enough that it has reduced compression flexibility and a large repulsive force occurs when it is compressed. In addition, the manageability it deteriorates and, in its use as a sealing material, an element to be sealed may be deformed or the opening to be sealed may be enlarged due to the deformation of the element to be sealed. If a closed cell foamed rubber sheet has a compression set (70 ° C for 24 hours) of more than 60%, the foamed rubber sheet is deficient in the shape recovery property and its use as a material Waterproof / airtight shutter, can not keep your property waterproof for a long period of time. It is desirable that the compression set (70 ° C for 24 hours) of a closed cell foamed rubber sheet be as small as possible. Particularly, products having a compression set of 55% or less are preferable due to their excellent recovery property. Compression deformation is more preferable from 5 to 55%, and particularly preferably from 5 to 45%. The alveolar rubber sheet of the present invention preferably shows a compression load of 50% as measured in accordance with JIS K6767 of 60 kPa or less. The lower limit of the 50% compression load is not particularly limited, but is preferably 10 kPa or more since, in use as an impermeable / hermetic sealing material, the impermeable property can be further improved. If the 50% compression load is greater than 60kPa, the alveolar rubber sheet can not sufficiently follow the shape of a portion to be sealed due to insufficient flexibility. This will result in the generation of a opening between the leaf and the portion to be sealed, which will cause a poor waterproof property. That is, the alveolar rubber sheet of the present invention preferably has a 50% compression load of 60 kPa or less (and 10 kPa or more) and therefore exerts an excellent impervious property even though it develops low repulsion. As a result, an excellent waterproof / airtight sealant material can be provided. The closed-cell alveolar rubber sheet of the present invention is obtained by subjecting a foamable raw material composition containing a resin composed mainly of a rubber-based resin to interlacing treatment and foaming treatment. The production method thereof is not particularly limited and known methods can be used. Examples include (1) a method wherein a foamable feedstock composition comprising a rubber-based resin, an entanglement agent, a thermal decomposition foaming agent and, if necessary, a filler or the like are kneaded in a kneader such as a Banbury mixer or a pressurization kneader, then it is continuously kneaded in a calender, an extruder, a conveyor belt molding machine or the like to produce a foamable sheet, and the non-interlaced foamable sheet is heated to be entangled and, simultaneously or after, foamed, producing a closed-cell alveolar rubber sheet, (2) a method wherein a foamable feedstock composition comprising a rubber-based resin, an entanglement agent, an agent of foaming thermal decomposition type and, if necessary, a filling substance or the like are kneaded with a mixing roller or the like, and the kneaded composition is fed into a mold, whereby it is simultaneously molding and interlacing and foaming, producing a closed-cell alveolar rubber sheet, (3) a method wherein a foamable raw material composition comprising a rubber-based resin, a thermal decomposition foaming agent and, if necessary, a filler or are kneaded in a kneader such as a Banbury mixer or a pressurization kneader, then continuously kneaded in a calender, an extruder, a conveyor belt molding machine or the like to produce a foamable sheet, and the foamable sheet is irradiated with an ionizing radiation to be interlaced, and then the foamable foil is heated to be foamed, producing a closed cell foamed rubber sheet, (4) a method for producing a foamed alveolar rubber sheet closed wherein a foamable feedstock composition comprising a rubber-based resin, an entanglement agent, a thermal decomposition foaming agent and, if necessary, a filler or the like are kneaded in such a kneading machine as a Banbury mixer or a pressurization kneader, then they are continuously kneaded in a calender, an extruder, a conveyor molding machine or the like to produce a foamable sheet, and the non-interlaced foamable sheet is heated to be foamed to produce a foam article molded, and the molded foam article is heated to interlace, (5) a method for producing a closed cell foamed rubber sheet wherein a foamable raw material composition comprising a rubber-based resin, a decomposition-type foaming agent thermal and, if necessary, a filler or the like are kneaded in a kneader such as a Banbury mixer or a pressurization kneader, then they are continuously kneaded in a calender, an extruder, a conveyor belt molding machine or the like to produce a foamable sheet, and the non-interlaced foamable sheet is heated to be foamed to produce a molded foam article, and the molded foam article is irradiated with an ionizing radiation to be interlaced, and (6) a method wherein a foamable feedstock composition comprising a rubber-based resin, an entanglement agent, a defoaming type foaming agent thermally and, if necessary, a filler or the like are kneaded in a kneading machine such as a Banbury mixer or a pressurization kneader, then kneaded continuously in a calender, an extruder, a molding machine of conveyor belt or the like to produce a foamable sheet, and the foamable sheet is irradiated with ionizing radiation to be interlaced, and the foamable sheet is heated to be foamed and then interlaced by the interlacing agent, producing a rubber sheet closed cell alveolar. Rubber-based resins are only required to be contained in a 50% by weight or more in the foamable raw material compositions. Examples of the entangling agents mentioned above include organic peroxides, sulfur and sulfur compounds. Organic peroxides are preferred. Examples of ionizing radiation include light, a? -rayo and an electronic beam. Examples of the organic peroxides mentioned above include diisopropylbenzene hydroperoxide, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, tere-butyl perbenzoate, cumyl hydroperoxide, tertiary or butyl hydroperoxide, 1,1-di (tert-butylperoxy) -3,3,5-trimethylhexane, n-butyl-4,4-di (tert-butylperoxy) valerate, a, a'-bis (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di ( tert-butylperoxy) hexyne-3, and tert-butylperoxymen. Examples of the sulfur compounds include tetra methylthiuram sulfide, tetramethylthiuram sulfide, zinc dimethyldithiocarbamate, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, monochloride Sulfur and sulfur dichloride. Physical entanglement by irradiation of ionizing radiation and chemical entanglement using an entanglement agent can be used together. Specifically, a closed cell foamed rubber sheet can be produced by kneading, in a kneader, a foamable feedstock composition comprising a rubber-based resin, an entanglement agent, a thermal decomposition foaming agent, and a filling substance, a stabilizer or whatever similar, added if necessary, followed by kneading continuously in an extruder or the like to produce a foamable foil, then the entanglement of the foamable foil by irradiating the foamable foil not interlaced with an ionizing radiation, heating the foil foamable for foaming, and then further entanglement using an entanglement agent. It is desirable to use an interlacing agent having a half-life temperature one minute higher than the decomposition temperature of a thermal decomposition type foaming agent. The reason for this is that by using a foaming agent such as thermal decomposition and an interlacing agent satisfying the conditions mentioned above, it is possible to perform entanglement after foam molding and obtain a sheet of alveolar rubber having high dimensional stability. In addition, it is also possible to obtain a foam having a high expansion ratio and a high degree of entanglement. The decomposition temperature of a thermal decomposition type foaming agent means a temperature at which the thermal decomposition type foaming agent initiates rapid decomposition. Specifically, it refers to a temperature where the weight decreases by 50% by weight when the measurement is conducted by thermogravimetric (TG) analysis at a temperature that rises rapidly to 1 ° C / minute. The content of the entanglement agent in the foamable feedstock composition can be adjusted appropriately depending on the properties of the rubber-based resin and the application of the closed-cell alveolar rubber sheet. Specifically, in the case of performing the entanglement treatment of a foamable feedstock composition by using only one entanglement agent, the content of the entanglement agent in the foamable feedstock composition is preferably 0.1 to 10 parts by weight, and more preferably from 0.2 to 7 parts by weight based on 100 parts by weight of the rubber based resin since if it is very small, the gel fraction (degree of entanglement) of the foamable raw material composition can not be suitable for foaming, resulting in the breaking of the foam, which can lead to not being able to obtain a closed-cell alveolar rubber sheet; conversely, if the content is very large, the gel fraction (degree of entanglement) of the foamable raw material composition can become very high and, as a result, the foamable raw material composition may not be foamed. In the case of performing the interlacing treatment of a foamable feedstock composition by the combined use of an entanglement agent and an ionizing radiation, when the half-life temperature of the interlacing agent is one minute higher than the temperature of decomposition of the thermal decomposition foaming agent, the content of the interlacing agent in the foamable raw material composition is preferably 0.05 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight based on 100 parts in weight of the resin based on rubber since if it is very small, the effect caused by the addition of the entanglement agent can not be developed; conversely, if it is too large, a closed-cell alveolar rubber sheet can become hard to have reduced compression flexibility. In the case of carrying out the entanglement treatment of a foamable feedstock composition by combined use of an entanglement agent and an ionization radiation, when the half-life temperature of the entanglement agent is lower than that of the interlacing agent. thermal decomposition foaming agent decomposition temperature, the content of the entanglement agent in the foamable raw material composition is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the rubber-based resin because if is too small, the gel fraction (degree of entanglement) of the foamable raw material composition can not become suitable for foaming, resulting in foam breakage, which can lead to failure in obtaining a rubber sheet closed cell alveolar; conversely, if the content is too large, the gel fraction (degree of entanglement) of the foamable feedstock composition may become too high and, as a result, the foamable feedstock composition may not be formed. The content of the thermal decomposition foaming agent in a foamable feedstock composition is preferably from 3 to 20 parts by weight, and more preferably from 5 to 15 parts by weight based on 100 parts by weight of the rubber based resin because if it is too small, the expansion ratio of a cell alveolar rubber sheet closed can not become high, resulting in a high bulk density, and as a result, the closed cell alveolar rubber sheet can develop a high repulsive force; inversely; if it is too large, the apparent density of a closed-cell alveolar rubber sheet can become low, resulting in a large compression deformation and the reduced-form recovery property of the closed-cell alveolar rubber sheet, and when the closed-cell alveolar rubber sheet is used as an impermeable / impenetrable clogging material it may be impossible to keep the property impermeable over a long period of time. The dose of ionization radiation, which can be appropriately adjusted depending on the property of the rubber-based resin or the application of the closed-cell alveolar rubber sheet, is preferably 0.5 to 10 Mrad, and more preferably 0.7 to 5.0 Mrad. The gel fraction of the alveolar rubber sheet is preferably 40 to 95% by weight, and more preferably 60 to 85% by weight. If the gel fraction is too low, the compression deformation can become too large. Conversely, if the gel fraction is too high, the compression flexibility can be improved. The rubber-based resin in the present invention is not particularly limited, if it has elasticity of rubber at room temperature. Their examples include at least one rubber selected from chloroprene rubber (CR), isoprene rubber (IR), butyl rubber (MR), nitrile rubber (nitrile-butadiene rubber) (NBR), natural rubber, rubber styrene-butadiene copolymer (SBR), butadiene rubber (BR), urethane rubber, fluoro rubber, acrylic rubber, and silicone rubber. Particularly, at least one rubber selected from nitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR), butyl rubber (MR) and chloroprene rubber (CR) is preferred because of its excellent cushioning property and durability. Nitrile-butadiene rubber (NBR) is also called nitrile rubber or acrylonitrile-butadiene copolymer rubber. Styrene-butadiene copolymer rubber (SBR), which is a copolymer rubber made from butadiene and styrene, is also called styrene rubber. In the present invention, a crystalline resin or a high softening point resin can also be incorporated into the foamable raw material composition composed mainly of a rubber-based resin, as an additive for improving the dimensional stability of the sheet. closed cell alveolar rubber. The melting point of a crystalline resin and the softening point of a high softening point resin is preferably 25 ° C or higher, and more preferably 50 to 200 ° C because when these are too low, it may be impossible to improve dimensional stability of a closed cell alveolar rubber sheet. The melting point of a crystalline resin means a measurement determined in accordance with JIS K7121. The softening point of a high softening point resin means a measurement determined in accordance with JIS K2207. The crystalline resin is preferably at least one resin selected from polyolefin-based resins such as polyethylene-based resin and polypropylene-based resin, ethylene-vinyl acetate copolymers, poly (vinyl acetate), ethylene-vinyl chloride copolymers , poly (vinyl chloride), and poly (vinylidene chloride). Polyethylene-based resin is not particularly limited, and its examples include ethylene-alpha-olefin copolymers, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, linear medium density polyethylene and polyethylene linear high density. These can be used individually or in combination. Examples of the alpha-olefin include alpha-olefins such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, -hexene, 1-octene, 1-nonene and 1 -decene. Examples of the polypropylene-based resin are not particularly limited and their examples include propylene homopolymers and propylene-alpha-olefin copolymers. The propylene-alpha-olefin copolymer may be a block copolymer, a random copolymer, or a random block copolymer. Examples of the alpha-olefin include alpha-olefins such such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1 -decene. Examples of high softening point resin include rosin-based resins, terpene-based resins and petroleum resins. Terpene-based resins are preferred from the viewpoint of the foamability of a foamable feedstock composition. As described above, the incorporation of a crystalline resin or a high softening point resin into a foamable raw material composition makes it possible to control the shrinkage of a rubber-based resin by causing a crystalline region of the crystalline resin or a glassy region of the high softening point resin to enter between molecular chains of the rubber-based resin. Therefore, when the closed cell alveolar rubber sheet is used as a waterproof / hermetic sealing material, the interfacial adhesion with a structural element for which the impermeability is applied can be improved and the impervious property can also be improved. The amount of the crystalline resin or high softening point resin to be added to the foamable raw material composition is preferably 1 to 50 parts by weight, and more preferably 5 to 30 parts by weight based on 100 parts by weight of the rubber-based resin because it is too small, it may be impossible to prevent a closed-cell alveolar rubber sheet from contracting, and conversely, if it is too large, a rubber sheet Closed cell alveolar may have insufficient flexibility. For the purpose of adjusting the physical properties of closed-cell alveolar rubber sheet, vulcanization accelerators, vulcanization acceleration aids, vulcanization decelerators, softeners, fillers, anti-aging agents, antioxidants, pigments, dyes, anti-aging agents funguses, foaming aids, flame retardants, flame retardant auxiliaries, and the like can be added to the foamable raw material composition. Examples of vulcanization accelerators include aldehyde-ammonia, aldehyde-amines, guanidines, tlazoles, sulfenamides, thiurams, dithiocarbamic acids, xanthogenic acids, and thioureas. Examples of vulcanization acceleration aids include zinc oxide, zinc carbonate, magnesium oxide, minium, calcium hydroxide, stearic acid, zinc stearate, amines, and diethylene glycol. Examples of the vulcanization decelerators include organic acids, such as italic anhydride, benzoic acid and salicylic acid, and amines, such as N-nitrosodiphenylamine and N-nitrosophenyl-beta, naphthylamine. In addition, acrylic-based polymers such as polyalkyl (meth) acrylates and polyvinyl chloride and may also be added in order to adjust the viscosity or gel fraction of the foamable raw material composition. It is desirable to incorporate a softener into the composition of foamable raw material composed mainly of a rubber-based resin in order to improve foamability and dimensional stability of closed-cell foamed rubber sheets. By incorporating a softener, a closed-cell alveolar rubber sheet is softened and whereby the distortion generated in the closed-cell alveolar rubber sheet can be relaxed evenly. As a result, the dimensional stability of the closed-cell alveolar rubber sheet is improved. The softener to be incorporated may be one conventionally known, but a softener which is compatible with a resin is preferred. The amount of a softener to be added is preferably from 1 to 50 parts by weight based on 100 parts by weight of a rubber-based resin, and more preferably from 15 to 30 parts by weight from a viewpoint of safe foamability and reduction of the force of contraction. Examples of softeners include paraffins such as chlorinated paraffin and liquid paraffin, glitter, animal or vegetable oils such as linseed oil, petroleum resins, process oils, lubricating oils, petroleum asphalt, petroleum based softeners such as petrolatum , mineral tar-based softeners such as mineral tar and pitch tar, softeners based on fatty oil such as castor oil, linseed oil, naba seed oil and coconut oil, waxes such as byproduct of pulp production wood chemistry, oil seat layer, beeswax, carnauba wax and lanolin, fatty acids such as ricinoleic acid, palmitic acid and stearic acid, fatty acid esters such as phthalates, fatty acid salts such as barium stearate, calcium stearate and zinc lanolin, phosphates, alkylsulfonates and thickeners. Examples of the filler include talc, calcium carbonate, bentonite, carbon black, fumed silica, aluminum silicate, acetylene carbon black, and aluminum powders. Examples of flame retardant include metal hydroxides such as aluminum hydroxide and magnesium hydroxide, flame retardants based on bromide such as decanobromodiphenylether, and phosphorus-based flame retardants such as ammonium polyphosphate. Examples of flame retardant auxiliaries include antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, sodium pyroantimonate, antimony trichloride., antimony trisulfide, antimony oxychloride, perchlo pentane antimony dichloride and potassium antimonate, boron compounds such as zinc metaborate, zinc tetraborate, zinc borate and basic zinc borate, zirconium oxides, tin oxides and oxides of molybdenum. The foaming treatment method for use in the present invention can be any one of the known methods including the method described in "Plástic Foam Handbook", edited by Hiroshi Maki and Atsushi Osakada, Nikkan Kogyo Shimbun Co. (1973). The foaming agent of the thermal decomposition type refers to a substance that decomposes in heating to generate a foamed gas Said foaming agent of the thermal decomposition type is not particularly limited and its examples include azodicarbonamide, benzenesulfonyl hydrazide, dinitrosopentamethylenenetetramine, toluenesulfonyl hirdazide, and 4,4-oxybis (benzenesulfonyl hydrazide). These foaming agents of the thermal decomposition type can be used individually or in combination of two or more. The amount of the thermal decomposition foaming agent added to the foamable raw material composition is preferably 1 to 30 parts by weight based on 100 parts by weight of a rubber-based resin. The expansion ratio of the closed-cell alveolar rubber sheet of the present invention is not particularly limited, but in order to achieve a bulk density of 30 to 100 kg / m3, an expansion ratio of about 10 or more is desirable, for example. The thickness of the closed cell alveolar rubber sheet is not particularly limited, but for use as an impermeable / hermetic sealing material, it is generally within the range of 1 to 20 mm, and preferably is within the range of 3 to 5. mm. Another embodiment of the present invention is a laminate including the closed cell foamed rubber sheet described above. That is, the laminate of the present invention is comprised of the closed cell foamed rubber sheet described above and a resin layer which is integrally laminated on one side or both sides of the closed cell foamed rubber sheet and having a melting point or a softening point lower than the temperature during foaming of the foamable raw material composition to be used as the raw material of the closed cell foamed rubber sheet. The effect derived from the inclusion of the resin layer on one side or both sides of the closed cell foamed rubber sheet is as follows. During use, with respect to the closed cell foamed rubber sheets composed mainly of a rubber-based resin, when the foamed rubber sheets are laminated during production or a foamed sheet is rolled up to form a roll, the foils Alveolar rubber sheet are subject to blockage due to the stickiness derived from the rubber and, as a result, it can become difficult to separate the sheets of alveolar rubber. Further, in the use of a closed cell foamed rubber sheet as a sealing material, in order to improve the adhesion at the interface between a portion to be sealed and the foamed rubber sheet, a foamed rubber sheet having a slight stickiness on its surface. Therefore, the alveolar rubber sheet becomes more subject to blockage. To solve the problems, by integrally laminating a viscosity-free material, mainly, a non-foamed resin layer for one or both sides of the closed-cell foam rubber sheet, it becomes possible to prevent blocking in time of lamination of alveolar rubber sheets or rolling on a roller. In the use of said laminate as a sealing material, in order to improve the adhesion between a portion to be sealed and the sheet of alveolar rubber, it is effective to apply a pressure sensitive adhesive to the viscosity-free resin layer by conventional means prior to arranging the closed cell foamed rubber sheet to the portion to be sealed. The resin layer used in the present invention is not particularly limited if it has a melting point or a softening point lower than the temperature during foaming of the foamable raw material composition to be used as a primary network of the rubber sheet closed cell alveolar. Their examples include films made from polyolefin-based resins such as low density polyethylene, high density polyethylene, linear low density polyethylene., polypropylene and ethylene-vinyl acetate copolymers. Said resins can be used individually or in combination of two or more. The melting point of the resin constituting the resin layer means a measurement determined in accordance with JIS K7121. The softening point of the resin constituting the resin layer means a measurement determined in accordance with JIS K2207. In particular, the resin having a melting point or a softening point lower than the temperature in the foaming time is not particularly limited. However, since it preferably extends together with a foamable raw material composition at the time of foaming the foamable raw material composition as described below, the resin should be extended at the time of foamed From this point of view, polyolefin-based resins having a melting point of 170 ° C or lower are preferred, and polyethylene-based resins having a melting point of 130 ° C or lower are more preferred. In addition, high density polyethylene having high tensile strength is most preferable because it does not extend by the tension applied to the sheet in the direction of flow. The thickness of the resin layer is preferably 5 to 100 μ? T ?. The resin layer preferably has no tack on its surface. As its standard, the peel strength, which is determined by the preparation of two laminates, superimposing the laminates with the resin layer of a laminate that is on the closed cell foamed rubber sheet of the other laminate, and measuring the resistance to the laminate. detachment in accordance with JIS K6854-2, is preferably 50 N / 25 mm or less, and more preferably 20 N / 25 mm or less. An example of the method for integrally laminating a resin layer on one side or both sides of a closed cell foamed rubber sheet is a method in which a film for forming the resin layer is prepared by a conventionally known method , a laminated sheet is prepared by laminating the film on one side or both sides of a foamable sheet made of a foamable raw material composition, and the interlacing and foaming treatment of the foamable foil is carried out by heating the foamed sheet. the sheet laminated and with which an alveolar cell rubber sheet is formed closed from the foamed sheet and at the same ta resin layer is laminated integrally on one side or both sides of the closed cell foamed rubber sheet to produce a laminate. The film for the formation of the resin layer can be produced by, for example, extrusion forming or by the die process T or the inflation method, calendering formation, or the solution casting process. The description provided above is directed to a process in which a film for the constitution of a resin layer and a foamed sheet made of a foamable raw material composition are prepared separately and the film is laminated integrally on one side or both sides of the foil. the foam sheet. An alternative is a method in which a foamed sheet is produced by forming a foam-like raw material composition in a sheet form and simultaneously a layer of resin is laminated integrally on one side or both sides of the foamed sheet to produce a rolled sheet , and the interlacing treatment and the foaming treatment of the foamed sheet are made by heating the laminated sheet and thereby forming a closed cell foamed rubber sheet from the foamed sheet to produce a laminate. As the method for integrally laminating a resin layer on one side and both sides of a foamed sheet to produce a laminated sheet, the extrusion lamination process and the coextrusion process are suitable.

A laminate can also be formed by lamination integrally, on one side or both sides of the closed cell foamed rubber sheet or on one side or both sides of the laminate, a different foamed layer of the closed cell foamed rubber sheet. Said foamed layer is not particularly limited and its examples include foamed sheets of polyolefin-based resin, foamed sheets of rubber-based resin, foamed sheets of polyurethane-based resin. Foam-based sheets of resin based on polylefine and foamed sheets of rubber-based resin are preferred. The description about the polyolefin-based resin is omitted because the resin is the same as the polyolefin-based resin that makes up the resin layer. The foamed sheet of resin based on polyolefin preferably has a closed cell ratio of 80% or more. The description about the method of measuring the closed cell ratio of a foamed sheet of polyolefin-based resin is omitted because the method is the same as the method of measuring the closed-cell ratio of a sheet of alveolar rubber of closed cell. The foamed sheet for the constitution of a foamed layer may be a foamed closed-cell sheet or an open-cell foamed sheet. From the point of view of secure hermetic property, a closed cell foamed sheet is preferred. The bulk density of the foamed sheet for the constitution of a foamed layer is preferably 20 to 100 kg / m3, and more preferably 22 to 70 kg / m3 from the point of view that flexibility compression and manageability can be made compatible. The foamed layer may contain conventionally known additives such as antioxidants, fillers, stabilizers, UV absorbers, pigments, antistatic agents, plasticizers, flame retardants, and flame retardant aids. As the method for integrally laminating a foamed layer on one side or both sides of the closed cell foamed rubber sheet or on one side or both sides of the laminate, known methods are used. Examples thereof include the thermal lamination process, the pressure sensitive adhesive lamination process, the adhesive lamination process, a method using a double sided tape, and a method using a hot melt adhesive. In addition, a pressure sensitive adhesive layer can also be disposed on one side or both sides of a closed cell foamed rubber sheet or on one side or both sides of a laminate. In other words, when the laminate is composed of a closed cell foamed rubber sheet and an integrally laminated resin layer on one side or both sides of the closed cell foamed rubber sheet, the pressure sensitive adhesive layer is laminated integrally on the surface of the outermost selected layer of the closed cell foamed rubber sheets or the resin layer constituting the laminate. When the laminate is composed of a closed cell foamed rubber sheet, a layer of resin laminated integrally on one side or both sides of the rubber sheet Closed-cell alveolar, and a foamed layer integrally laminated on one side or both sides of the closed-cell foamed rubber sheet or the resin layer, the pressure-sensitive adhesive layer is integrally laminated to the surface of the outermost layer selected from closed-cell alveolar rubber sheets, the resin layer or the foamed layer. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and, for example, pressure-sensitive adhesives based on polyurethane, acrylic-based pressure sensitive adhesives, and sensitive adhesives can be used. the pressure based on rubber. From the point of view of being superior in adhesion and removal and being compatible in a high waterproof property and high workability, the use of a pressure sensitive adhesive based on polyurethane is desirable. The pressure sensitive adhesive based on polyurethane is produced by reacting a raw material containing a polyol and a polyisocyanate. Examples of the polyol include polyester polyols and polyether polyols. The polyester polyol is a product obtained by reacting a polycarboxylic acid component and a polyol component. Examples of said polycarboxylic acid component include terephthalic acid, adipic acid, azelaic acid, sebacic acid, italic anhydride, isophthalic acid, and trimellitic acid. Examples of the polyol component include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexanoglycol, 3-methyl-1, 5- pentanediol, 3,3'-d.methylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerol, trimethylolpropane, pentaerythritol, and polyester polyols, produced by open ring polymerization of lactones, such as polycaprolactone, poly ( p-methyl-and-valerolactone) and polyvalerolactone. Polyether polyols can be obtained by polymerizing an oxirane compound using a low molecular weight polyol as an initiator. Examples of the oxirane compound include ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran. Examples of the low molecular weight polyol include propylene glycol, ethylene glycol, glycerol, and trimethylolpropane. The polyisocyanate can be classified into aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. Examples of the aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, diisocyanate 2,6-tolylene, 4,4'-toluidine diisocyanate, toluene 2,4,6-triisocyanate, 1, 3,5-benzene triisocyanate, dianisidine diisocyanate, 4,4'-diphenyl diisocyanate, and triisocyanate of 4,4,4'-triphenylmethane. Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

Examples of araliphatic polyisocyanates include α, β'-diisocyanato-1,3-dimethylbenzene, α, β'-diisocyanato-1,4-dimethylbenzene, β, β'-diisocyanato-1,4-diethylbenzene, 1,4-diisocyanate tetramethylxylylene and 1,3-tetramethylxylylene diisocyanate. In addition, examples of alicyclic polyisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, di-cyanoacetate, 4-cyclohexane, methyl-2,4-diisocyanate. cyclohexane, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), and 1,4-bis (isocyanatomethyl) cyclohexane. The closed-cell alveolar rubber sheet or the laminate of the present invention can be suitably used for sealing materials in various fields such as architecture, construction, electrical engineering, electronics and vehicles. In particular, they can be suitably used as an impermeable / hermetic sealing material or a hermetic sealing material because they have an effect showing superior interfacial adhesion with a structural element for which waterproofing is applied and a superior impermeability property. for a long period of time, and reliability can be improved.

EXAMPLES The present invention is described in more detail below by way of examples and comparative examples, but the invention is not limited to these examples.

EXAMPLE 1 An foamable foil is obtained, not entangled when kneading a foamable raw material composition composed of 100 parts by weight of an acrylonitrile-butadiene copolymer rubber (NBR, density = 0.96 g / cm 3) as a main ingredient, 15 parts in weight of azodicarbonamide ("SO-L" produced by Otsuka Chemical Co., Ltd, decomposition temperature = 197 ° C) and 0.1 parts by weight of a phenol-based antioxidant (product name "IRGANOX 1010" produced by Ciba Specialty Chemicals) ) using a pressurized kneader, feeding the foamable raw material composition to an extruder, kneading in the molten state and extruding. By irradiating the resulting foamable sheet with an electron beam in a dose of 2 Mrad and an acceleration voltage of 500 keV, a non-foamed, interlaced foamable sheet is obtained. The non-foamed, interlocked foamed sheet is heated to 240 ° C in a foaming oven. Whereupon the azodicarbonamide is decomposed and the foamable sheet is foamed. With which a closed cell alveolar rubber sheet having a bulk density of 35 mg / m3 and a thickness of 2.5 mm is obtained.

EXAMPLE 2 A closed cell foamed rubber sheet having a bulk density of 56 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in Example 1 except by changing the addition amount of azodicarbonamide to 10 parts by weight.

EXAMPLE 3 A closed-cell alveolar rubber sheet having a bulk density of 85 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except by changing the addition amount of azodicarbonamide to 6 parts by weight.

EXAMPLE 4 A closed-cell alveolar rubber sheet having a bulk density of 35 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except for the addition of 0.5 parts by weight of diisopropylbenzene hydroperoxide (name of product "PERCUMYL P" produced by NOF Corp., a half-life temperature of one minute = 230 ° C), which is an entanglement agent, for the formulation of example 1.

EXAMPLE 5 A closed-cell alveolar rubber sheet having a density of 35 kg / m3 and a thickness of 2.5 mm is obtained by the same method as in example 4 except by changing the addition amount of diisopropylbenzene hydroperoxide (product name = "PERCUMYL P" produced by NOF Corp., a half-life temperature of one minute = 230 ° C) to 1.0 part by weight.

EXAMPLE 6 A closed cell foamed rubber sheet having a bulk density of 35 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except for the addition of 15 parts by weight of 2-ethylhexyl phthalate (produced by Wako Puré Chemical Industries, Ltd.) as a softener.EXAMPLE 7 A closed cell foamed rubber sheet having a bulk density of 35 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except for the addition of 10 parts by weight of a terpene resin ( Product name "CLEARON P 25" produced by Yasuhara Chemical Co., Ltd .; softening point = 125 ° C), which is a high softening point resin, as an additive.

EXAMPLE 8 On one side of the closed-cell alveolar rubber sheet obtained from example 1, a pressure sensitive adhesive based on polyurethane (product name = "CYABINE SP-205" produced by Toyo Ink Mfg. Co., Ltd.) applied in a thickness of 20 μ? t ?, producing a laminate in which a pressure-sensitive adhesive layer is integrally laminated to one side of the closed cell foamed rubber sheet.

EXAMPLE 9 On one side of the closed-cell alveolar rubber sheet obtained in example 1, an acrylic-based temperature sensitive adhesive (product name = "BPS3180" produced by Toyo Ink Mfg. Co., Ltd) is applied in a thickness of 20 μ? t ?, producing a laminate in which a pressure sensitive adhesive layer is integrally laminated to one side of the closed cell foamed rubber sheet.

EXAMPLE 10 A laminate including a closed-cell foamed rubber sheet having a bulk density of 56 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in Example 1 except by changing the addition amount of azodicarbonamide to 10. parts by weight and extrusion lamination of a high density polyethylene film having a thickness of 40 μ? t? (product name = "HD" produced by Tamapoly Co., Ltd .: melting point = 134 ° C) as a resin layer on one side of the foamable foil, not foamed, not interlaced during extrusion of the foamable foil. After winding the closed-cell alveolar rubber sheet in a roll, blocking does not occur. The peel strength of the laminate resin layer is 10 N / 25 mm. In evaluations of adhesive strength and impervious property, a double-sided tape (product name "5761" produced by Sekisui Chemical Co., Ltd.) is adhered to the resin layer of the laminate and then the sample is used for the evaluations with the removal of released paper.

EXAMPLE 11 A laminate having a thickness of 3.5 mm is obtained by lamination integrally, by the process of pressure-sensitive adhesive lamination, a foamed polyethylene sheet (product name) "SOFTLON FR-ND # 3001" produced by Sekisui Chemical Co., Ltd .; closed cell ratio = 92%, bulk density = 33 kg / m3) for one side of the closed-cell alveolar rubber sheet obtained in example 1.

EXAMPLE 12 A closed-cell foamed rubber sheet having a bulk density of 35 kg / m3 and a thickness of 3.5 mm is obtained by the same method as in example 1 except by adjusting the closed cell foamed rubber sheet which may have a thickness of 3.5 mm.

COMPARATIVE EXAMPLE 1 A closed cell foamed rubber sheet having a bulk density of 25 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except by changing the addition amount of azodicarbonamide to 20 parts by weight.

COMPARATIVE EXAMPLE 2 A closed-cell alveolar rubber sheet having a bulk density of 110 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except by changing the amount of addition of azodicarbonamide to 4 parts by weight.

COMPARATIVE EXAMPLE 3 A closed cell foamed rubber sheet having a bulk density of 40 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 1 except using 100 parts by weight of an ethylene-propylene copolymer rubber (EPDM, density = 0.87 g / cm3) as a main raw material and by changing the addition amount of azodicarbonamide to 10 parts by weight.

COMPARATIVE EXAMPLE 4 A closed-cell alveolar rubber sheet having a bulk density of 67 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in comparative example 3 except by changing the addition amount of azodicarbonamide to 6 parts by weight .

COMPARATIVE EXAMPLE 5 A closed-cell alveolar rubber sheet having a bulk density of 98 kg / m3 and a thickness of 2.5 mm is obtained by the same method as in comparative example 3 except when changing the addition amount of azodicarbonamide to 4 parts by weight.

COMPARATIVE EXAMPLE 6 A closed cell foamed rubber sheet having a bulk density of 201.6 kg / m3 and a thickness of 2.5 mm is obtained by the same method as in example 5 except when changing the entanglement agent to 2.5-dimethyl -2,5-bis (tert-butylperoxy) hex-3-ino (product name "PERHEXYNE 25B" produced by NOF Corp., a half-life temperature of one minute = 190 ° C).

COMPARATIVE EXAMPLE 7 A closed cell foamed rubber sheet having a bulk density of 10 kg / m 3 and a thickness of 2.5 mm is obtained by the same method as in example 5 except by changing the crosslinking agent to dicumyl peroxide (produced by NOP Corp. ., a half-life temperature of one minute = 170 ° C).

COMPARATIVE EXAMPLE 8 An attempt is made to obtain a laminate by the same method as in example 1 except by changing the amount of addition of azodicarbonamide at 10 parts by weight and the extrusion lamination of a polyethylene terephthalate film having a thickness of 50 μ? (product name? 5000"produced by Toyobo Ltd., softening point = 260 ° C) as a resin layer on one side of foamable foamed sheet, not entangled during extrusion of foamable sheet. laminate is not obtained because the resin layer does not extend during foaming of the foamable sheet.

Evaluation For the closed cell and laminated foamed rubber sheets obtained above, the following properties are evaluated. (1) bulk density (kg / m3) of closed-cell alveolar rubber sheet: the measurement is made in accordance with JIS K7222. (2) compression deformation of closed-cell alveolar rubber sheet (Cs:%): the measurement is made under the conditions of 70 ° C for 24 hours in accordance with JIS K6262. It is noted that the closed-cell alveolar rubber sheets of Comparative Examples 3 to 5 have a compression deformation of more than 95%. (3) Compression load (kPa) in 50% compression of closed cell alveolar rubber sheet: measurements are made in accordance with JIS K6767. (4) Peel strength (kPa) of closed cell or laminated alveolar rubber sheet: the measurement is made in accordance with JIS K6850. The evaluation test conditions are as follows. As an adhesive component, a 2.5 mm thick closed-cell honeycomb sheet or a laminate is used. The thickness of the closed-cell alveolar rubber sheet or the laminate after adhesion is 2.5 mm. The test panels are acrylic plates with a dimension of 25 mm wide and 100 mm long. The overlapped area (adhesive area) is formed 25 mm wide and 12.5 mm long in length. The tension speed is adjusted to 50 mm per minute. In each case, the mode of rupture is interfacial detachment. The measurements are conducted immediately after the adhesion of a closed cell foamed rubber sheet and a laminate to an acrylic sheet, after 12 hours of aging at 23 ° C after the adhesion of the closed cell foamed rubber sheet and the laminate to the acrylic plate, and after 12 hours of aging at 70 ° C after the adhesion of the closed cell alveolar rubber sheet and the laminate to the acrylic plate. In Comparative Examples 3 to 5, the peel strength is less than 5 kPa under all conditions. (5) The gel fraction of a closed-cell alveolar rubber sheet is measured in the following procedure. 100 mg of a sheet of alveolar rubber are immersed in 25 ml of ethyl methyl ketone at 70 ° C (xylene at 110 ° C for comparative examples 3 to 5) for 7 to 22 hours and the undissolved matter is separated by filtration to through a 200 mesh wire mesh. The residue in the wire mesh is dried under vacuum and the weight A (mg) of the dried residue is measured. The gel fraction is calculated from the following formula. Fraction of gel (% by weight) = 100 X A / 100 (6) waterproof property; The evaluation is conducted by the following procedure. A specimen is prepared by cutting a closed-cell alveolar rubber sheet or a laminate in a ring shape having an outer diameter of 100 mm and an internal diameter of 80 mm (10 mm in width, 2.5 mm in thickness). This specimen is placed between two parallel acrylic resin plates, which are then forced to approach and arrange so that the compression ratio of the specimen reaches 50% (the distance between the acrylic plates = 1.25 mm). One of the two acrylic resin plates has an orifice with outlet to fill with water and to apply pressure in the portion corresponding to the central portion of the specimen. Distilled water is supplied through the outlet orifice and the space surrounded by the opposing surfaces of the two acrylic resin plates and the specimen is filled with it. In addition, a pressure of 15 kPa is applied. The period of time from the moment when the application of pressure begins and the moment when the water leakage is recognized is observed visually and evaluated as a time of impermeability (minutes). The moment when water leakage occurs, even when it is only a drop, it is recognized and determined as the end of the waterproof time. The evaluation is done immediately after the specimen is disposed between the Acrylic resin plates, and after 24 hours of aging at 70 ° C after disposal. The cases of a waterproof time of more than 72 hours are expressed as "no leakage" in tables 1 and 2.

Dimensional Stability From a closed cell foamed rubber sheet or a laminate, a specimen having a 100 mm flat rectangular shape in the extrusion direction of the closed cell foamed rubber sheet (hereinafter, referred to as "direction longitudinal ") and 100 mm in a direction along the planar direction of the closed-cell alveolar rubber sheet and perpendicular to the extrusion direction (hereinafter referred to as" transverse direction ") is cut. Subsequently, the specimen is allowed to age at 70 ° C for one week (7 days). Then, the dimensions of the specimen in the longitudinal direction, the transverse direction and the direction perpendicular to the surface of the closed-cell alveolar rubber sheet (hereinafter referred to as "thickness direction") is measured, followed by the calculation of the contraction ratio in each direction using the following formula. The greater proportion of contraction of that in the longitudinal direction and in the transverse direction is used as the index of dimensional stability in the planar direction. The shrinkage ratio in the thickness direction is used as the index of the dimensional stability in the thickness direction. The contraction ratio (%) = 100 x (the dimension before the aging - the size after aging) / the size before aging (8) Handleability (amount of flexion) A specimen is prepared by cutting a closed cell or laminated cell sheet of alveolar rubber into a flat rectangular shape 200 mm long and 50 mm wide. The specimen is fixed with one end in the supported longitudinal direction, with a 150 mm portion projecting into the air. One minute later, the amount of flexion at the free end of the specimen is measured. The results of the evaluations described above are shown in tables 1 and 2. For reference, expansion ratios are also shown. All the closed cell alveolar rubber sheets obtained in the examples have closed cell ratios greater than 90%.

TABLE 1 TABLE 2 I heard From the results of the evaluation in Tables 1 and 2, it is clear that the closed cell and laminated alveolar rubber sheets of Examples 1 to 11 are within the ranges of apparent density and compression set defined herein. invention and show high resistance to detachmentIn other words, they are excellent in interfacial adhesion with an element to be sealed (a structural element to which waterproofing property applies) and waterproof property evaluations are good. Regarding leaves foam rubber closed cell of Examples 4 and 5, the ratio of dimensional change (shrinkage) is reduced and the compression set is also reduced by using a crosslinking agent having a half-life temperature of one minute higher than the decomposition temperature of a foaming agent and entanglement application after foaming. Furthermore, it is clear that the leaves of foam rubber closed cell of Examples 6 and 7 have small rates of shrinkage and are excellent in dimensional stability because a softener or a resin of high softening point are incorporated. Leaves foam rubber closed cell with sensitive adhesive layer to the pressure of Examples 8 and 9, namely, the laminates can increase the peel strength remarkably and can further improve the waterproof property in comparison to a product having an adhesive layer not sensitive to pressure (example 1). They can be applied as sealing materials under severe conditions. On the other hand, according to the evaluation results in Table 2, the closed-cell alveolar rubber sheet of Comparative Example 1 is outside the range of compression deformation defined in the present invention and has a low peel strength, that is, it is deficient in interfacial adhesion. In addition, the evaluation of impervious property after aging at 70 ° C is deficient. The closed-cell alveolar rubber sheet of comparative example 2 is of low expansion and is outside the range of bulk density defined in the present invention. In addition, it develops a high compression load and is not good at handling. In addition, the closed-cell alveolar rubber sheets of Comparative Examples 3 to 5 are outside the range of compression deformation defined in the present invention and are low in peel strength, ie, deficient in interfacial adhesion. In addition, they are clearly deficient in the evaluation of impermeability property. As in Comparative Examples 6 and 7, in closed cell foamed rubber sheets prepared using an entanglement agent no higher than the decomposition temperature of a foaming agent, the entanglement is conducted before foaming. Therefore, the expansion ratio becomes not so high and the proportion of the dimensional change (contraction) is high. In addition, compression loading increases and handiness is poor.

According to the evaluation results in Table 1, the laminate of Example 11 is superior in stiffness to the single closed-cell alveolar rubber sheet of Example 12 and can improve workability.

Industrial Applicability The closed cell foamed rubber sheet or laminate of the present invention can be suitably used for sealing materials in various fields such as architecture, construction, electrical engineering, electronics and vehicles. It can be suitably used not only as an impermeable / hermetic sealing material but also as various types of sealing materials such as a hermetic sealing material, and also a soundproofing material and a sound isolation material.

Claims (1)

1. NOVELTY OF THE INVENTION CLAIMS 1 .- A sheet of closed cell alveolar rubber obtained by submitting a foamable raw material composition composed mainly of a rubber-based resin for the treatment of interlacing and foaming treatment and having a bulk density of 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262. 2 - The closed cell alveolar rubber sheet according to claim 1, further characterized in that the interlacing treatment is physical entanglement by ionization radiation or chemical entanglement using an organic peroxide or a sulfur compound. 3. The closed-cell alveolar rubber sheet according to claim 1, further characterized in that it exhibits a dimensional change ratio after aging at 70 ° C for 7 days of 20% or less in the longitudinal direction, cross section and direction of thickness. 4. - The closed cell alveolar rubber sheet according to claim 1, further characterized in that the composition of Foamable raw material comprises a foaming agent and an entanglement agent having a half-life temperature of one minute higher than the decomposition temperature of the foaming agent. 5. - The closed cell alveolar rubber sheet according to claim 1, further characterized in that the sheet has a gel fraction of 40 to 95% by weight. 6. - The closed cell alveolar rubber sheet according to claim 1, further characterized in that the rubber-based resin comprises at least one rubber selected from nitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR) , butyl rubber (II) and chloroprene rubber (CR). 7. - The closed-cell alveolar rubber sheet according to claim 1, further characterized in that the sheet has a compression load of 50% as measured in accordance with JIS K6767 of 60 kPa or less. 8. - The closed-cell alveolar rubber sheet according to claim 1, further characterized in that the sheet exhibits a peel strength as measured in accordance with JIS K6850 of 20 kPa or more immediately after adhesion to an acrylic plate. 40 kPa or more after aging at 23 ° C for 12 hours after adhesion, and 60 kPa or more after aging at 70 ° C for 12 hours after adhesion. 9. - The closed cell alveolar rubber sheet in compliance with claim 1, further characterized in that the foamable feedstock composition comprises 100 parts by weight of the rubber-based resin and from 1 to 50 parts by weight of a softener. 10. - The closed-cell alveolar rubber sheet according to claim 1, further characterized in that the foamable raw material composition comprises a crystalline resin having a melting point of 25 ° C or higher or a point-based resin. High softening that has a softening point of 25 ° C or higher. 11. - A laminate comprising a closed-cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100. kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, and a resin layer that is integrally laminated to one side or both sides of the closed cell foamed rubber sheet and having a melting point or softening point lower than the temperature during foaming of the foamable raw material composition to be used as the raw material of the foil closed cell alveolar rubber. 12. - The laminate according to claim 11, further characterized in that the resin layer comprises a polyolefin-based resin. 13. - The laminate according to claim 11, further characterized in that the resin layer has been laminated on one side or both sides of a foamable sheet comprising the foamable raw material composition prior to foaming the foamable raw material composition. 14. - A laminate comprising a closed-cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100. kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, and an integrally laminated pressure-sensitive adhesive layer on one side or both sides of the closed-cell alveolar rubber sheet. 15. A laminate comprising a closed-cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100. kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, a resin layer that is integrally laminated to a side or both sides of the closed-cell alveolar rubber sheet and having a melting point or softening point lower than the temperature during foaming of the foamable raw material composition to be used as the raw material of the closed cell foamed rubber sheet, and a pressure-sensitive adhesive layer integrally laminated to the foamed rubber sheet of closed cell or resin layer. 16. The laminate according to claim 14, further characterized in that the pressure sensitive adhesive layer comprises a pressure sensitive adhesive based on polyurethane produced by reacting a raw material comprising a polyol and a polyisocyanate. 17. The laminate according to claim 15, further characterized in that the pressure sensitive adhesive layer comprises a pressure sensitive adhesive based on polyurethane produced by reacting a raw material comprising a polyol and a polyisocyanate. 18. - A laminate comprising a closed cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, and a foamed layer laminated integrally on one side or both sides of the closed cell alveolar rubber sheet. 19. - A laminate comprising a sheet of alveolar rubber of closed cell obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100 kg / m3 as measured in accordance with JIS K7222 and a Compression strain of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, a layer of resin that is laminated integrally on one side or both sides of the closed cell foamed rubber sheet and having a melting point or softening point lower than the temperature during foaming of the foamable feedstock composition to be used as the raw material of the closed-cell foamed rubber sheet, and a foamed layer integrally laminated in the Closed cell alveolar rubber sheet or resin layer. 20. A laminate comprising a closed cell foamed rubber sheet obtained by subjecting a foamable raw material composition composed mainly of a rubber-based resin to interlacing treatment and foaming treatment and having a bulk density of 30 to 100. kg / m3 as measured in accordance with JIS K7222 and a compression set of 60% or less as measured under the conditions of 70 ° C for 24 hours in accordance with JIS K6262, a resin layer which is integrally laminated on one side or both sides of the closed cell honeycomb sheet and which has a melting point or softening point lower than the temperature during the foaming of the foamable raw material composition to be used as the raw material of the closed cell foamed rubber sheet, a foamed layer integrally laminated in the closed cell foamed rubber sheet or the resin layer and a laminated pressure sensitive adhesive layer integrally on the surface of the uppermost layer between the closed cell honeycomb sheet, the resin layer and the foamed layer. 21. An impermeable / hermetic sealing material comprising the closed cell honeycomb sheet or the laminate of any of claims 1 to 20.