JP7064089B2 - Foam rubber molded body, its manufacturing method, underwater clothing using it, cushioning material for vehicles, anti-vibration rubber, soundproof rubber and sealing material - Google Patents

Description

The present invention relates to a foamed rubber molded body containing biomass nanofibers, a method for producing the same, and underwater clothing using the same, a cushioning material for vehicles, a vibration-proof rubber, a soundproof rubber, and a sealing material.

Foamed rubber molded bodies made by cross-foaming natural rubber and various synthetic rubbers are excellent in lightness and heat insulation, so they are used for underwater clothing, rubber packing, oil seals, various sealing materials such as waterproof materials, and vehicles. It is used for various purposes such as cushioning material, anti-vibration rubber, sound-proof rubber, conveyor belt, roll surface member, wire covering member, various rubber sheets, and rubberized cloth in which a rubber sheet and a woven or knitted material are laminated.

On the other hand, in rubber-based materials, fibers are added as a reinforcing agent to increase the strength of rubber, which is the main component, to form a composite. For example, Patent Document 1 proposes a composite material obtained by adding fibrous fine cellulose to a polymer-based base material such as natural rubber or synthetic rubber to form a composite material. Patent Document 2 proposes a rubber composition containing cellulose having a crystallinity of less than 50% with respect to a diene-based rubber. Further, Patent Document 3 proposes a rubber-based crosslinked foamed molded product containing cellulose nanofibers, which is a kind of biomass nanofibers.

Japanese Unexamined Patent Publication No. 2004-231996 Japanese Unexamined Patent Publication No. 2011-137105 Japanese Unexamined Patent Publication No. 2016-191007

However, in the foam molded product using the rubber-based material described in Patent Document 1 and the rubber composition described in Patent Document 2, the shape of the closed cells contained inside the molded body is maintained, so that the shape after molding is maintained. However, if a large force is applied from the outside to deform it, the shape may be distorted and the bulk may not be restored, so-called "sagging" may occur. In particular, sagging after a long-term load is likely to occur, and reduction of sagging is required in various applications where a load is applied from the outside during use. Further, in the rubber-based crosslinked foamed molded article described in Patent Document 3, only the compatibility between weight reduction and wear resistance has been verified, but the reduction of sagging has not been verified.

In order to solve the above problems, the present invention provides a foamed rubber molded body that is less likely to cause settling, a method for producing the same, and underwater clothing, a cushioning material for vehicles, a vibration-proof rubber, a soundproof rubber, and a sealing material using the same. ..

In one embodiment, the present invention is a foamed rubber molded body containing a rubber component and biomass nanofibers, wherein the content of the biomass nanofibers in the foamed rubber molded body is 10% by mass or less, and JIS K 6767: The present invention relates to a foam rubber molded product according to 1999, wherein the 50% compression set measured 30 minutes after the load is removed is 28% or less.

In one embodiment of the present invention, the foam rubber molded product is JIS K 6767: 1999.
It is preferable that the 50% compression set measured 1 hour after the load is removed is 25% or less.

In one embodiment of the present invention, the rubber component is natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, ethylene propylene rubber, ethylene propylene diene. It is preferable to contain at least one selected from the group consisting of rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, urethane rubber, silicone rubber and fluororubber.

In one embodiment of the present invention, the foamed rubber molded body has an elongation at cutting of 300% or more and 1000% or less measured according to JIS K 6251: 2010, and is measured according to JIS K 6251: 2010. The tensile strength is preferably 300 kPa or more and 900 kPa or less. In the embodiment, the foam rubber molded product preferably has a 100% tensile stress of 85 kPa or less as measured in accordance with JIS K 6251: 2010. Further, in the embodiment, it is preferable that the foamed rubber molded body has a hardness of less than 40 measured using an ASKER® rubber hardness tester (durometer) CSC2 type manufactured by Polymer Meter Co., Ltd.

In one embodiment of the present invention, the foam rubber molded product preferably has a 100% tensile stress greater than 85 kPa as measured in accordance with JIS K 6251: 2010. In the embodiment, the foam rubber molded product has an elongation at cutting measured in accordance with JIS K 6251: 2010 of 50% or more and 500% or less, and a tensile strength measured in accordance with JIS K 6251: 2010. The value is preferably 350 kPa or more and 1500 kPa or less. Further, in the embodiment, the foam rubber molded product preferably has a 25% compressive stress of 10 kPa or more and 150 kPa or less measured in accordance with JIS K 6767: 1999. Further, in the embodiment, the hardness measured using the ASKER (registered trademark) rubber hardness meter (Durometer) CSC2 type manufactured by Polymer Meter Co., Ltd. is 40 or more, and the hardness is 40 or more, and the ASKER (registered trademark) manufactured by Polymer Meter Co., Ltd. is used. The hardness measured using a rubber hardness tester (durometer) C type is preferably 8 or more and 70 or less.

The present invention also has, in one embodiment, a master batch of biomass nanofibers obtained by mixing and solidifying a rubber component, a latex containing the same type of rubber component as the rubber component, and an aqueous dispersion of biomass nanofibers. The present invention relates to a method for producing a foamed rubber molded body, which comprises vulcanizing and foaming a rubber composition containing a vulcanizing agent and a foaming agent to obtain a foamed rubber molded body.

The masterbatch of the biomass nanofibers preferably contains the biomass nanofibers in a proportion of 0.1% by mass or more and 50% by mass or less.

The present invention relates to underwater clothing using the foamed rubber molded product in one embodiment. The present invention relates to a cushioning material for vehicles using the foamed rubber molded product in another embodiment. The present invention relates to a vibration-proof rubber using the foamed rubber molded product in another embodiment. The present invention relates to a soundproof rubber using the foamed rubber molded product in another embodiment. The present invention relates to a sealing material using the foamed rubber molded product in another embodiment.

The present invention relates to a foamed rubber molded body in which a rubber component and biomass nanofibers are contained in the foamed rubber molded body and the content of the biomass nanofibers is adjusted to a predetermined range. The foamed rubber molded body of the present invention is a foamed rubber molded body that conforms to JIS K 6767: 1999, has a 50% compression set of 28% or less measured 30 minutes after the load is removed, and is less likely to cause sagging. be. INDUSTRIAL APPLICABILITY The present invention can provide a foamed rubber molded body that is less likely to cause settling, as well as underwater clothing, a cushioning material for vehicles, a vibration-proof rubber, a soundproof rubber, and a sealing material using the same. The present invention also preferably comprises a foamed rubber molded body that is less prone to settling, has high flexibility, and has sufficient tensile strength, as well as underwater clothing using the same, cushioning materials for vehicles, and vibration-proof rubber. Soundproof rubber and sealing material can be provided.

According to the method for producing a foamed rubber molded body according to an embodiment of the present invention, a latex containing a rubber component and a rubber component of the same type as the rubber component and an aqueous dispersion of biomass nanofibers are mixed and solidified. By using the masterbatch of the obtained biomass nanofibers, it is possible to obtain a foamed rubber molded product that is less likely to cause sagging. Preferably, it is possible to obtain a foamed rubber molded product which is less likely to cause sagging, has high flexibility, and has sufficient tensile strength.

The inventors of the present invention have diligently studied the reduction of sagging in a foamed rubber molded product. As a result, the foamed rubber molded body obtained by incorporating the rubber component and the biomass nanofibers into the foamed rubber molded body and adjusting the content of the biomass nanofibers within a predetermined range conforms to JIS K 6767: 1999. The present invention was made by finding that the 50% compression set measured 30 minutes after the load was removed was 28% or less, resulting in a foamed rubber molded body that was resistant to settling. In addition, when fibers, which are reinforcing agents, are usually added to a polymer-based base material (matrix material) such as rubber, mechanical strength such as tensile strength and bending strength is increased, but flexibility such as elongation during cutting is increased. It tends to decrease. In the present invention, preferably, the rubber component and the biomass nanofibers are used, and the content of the biomass nanofibers is set within a specific range, in addition to reducing the compression set as described above, the actual usage situation. It was found that a foamed rubber molded body having a significantly improved flexibility can be obtained while maintaining a sufficient tensile strength.

The foamed rubber molded product contains a rubber component and biomass nanofibers.

The rubber component constituting the foamed rubber molded product is not particularly limited, and for example, natural rubber (NR) or synthetic rubber can be used. Examples of the synthetic rubber include diene-based rubber and non-diene-based rubber. Examples of the diene rubber include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Examples of the non-diene rubber include butyl rubber (also referred to as isobutylene isoprene rubber, IIR), chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), ethylene propylene rubber (EPR), and ethylene propylene. Diene rubber (EPDM), acrylic rubber (ACM), epichlorohydrin rubber (epichlorohydrin homopolymer (CO), epichlorohydrin and ethylene oxide copolymer (ECO), epichlorohydrin and allylglycidyl) Ethereal copolymer (GCO) and ternary copolymer of ethylene oxide, epichlorohydrin and allylglycidyl ether (GECO)), chlorosulfonated polyethylene (CSM), urethane rubber (U), silicone rubber, Fluorine rubber and the like can be mentioned. The rubber component may be used alone or in combination of two or more. In the foamed rubber molded body, the rubber component preferably contains one or more selected from the group consisting of natural rubber, chloroprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, acrylonitrile butadiene rubber and styrene butadiene rubber, and chloroprene rubber. It is more preferable to include it.

The chloroprene rubber is not particularly limited, and for example, any of a sulfur-modified type, a mercaptan-modified type, a xanthate-modified type, and other special types may be used. In the chloroprene rubber, the Mooney viscosity ML _{(1 + 4)} measured 4 minutes after preheating at 100 ° C. for 1 minute and then operating the rotor using an L-shaped rotor according to JIS K 630-1: 2013 is Although not particularly limited, the Mooney viscosity ML _{(1 + 4)} of the chloroprene rubber is preferably 10 or more and 120 or less from the viewpoint of excellent processability. The Mooney viscosity ML _{(1 + 4)} of the chloroprene rubber is more preferably 20 or more and 100 or less.
It is more preferably 30 or more and 90 or less. As such a chloroprene rubber, for example, a sulfur-modified type or the like can be used.

The biomass nanofibers refer to minute fibrous substances having a diameter of 1 nm or more and 1000 nm or less and an aspect ratio of 5 or more and 10,000 or less, which are obtained by refining biological raw materials. Examples of the biomass nanofibers include cellulose nanofibers (hereinafter, also referred to as CNF), cellulose nanocrystals, cellulose nanowhiskers, chitin nanofibers, and chitosan nanofibers. The cellulose nanofibers are, for example, pulverized and chemically treated (2,2,6,6-tetramethyl-1-piperidin-N-oxyradical and derivatives thereof) of the fibrous cellulose constituting the cell wall of a plant or wood. The chemical treatment used is given as an example), and it can be obtained by defibrating. The chitin nanofibers can be obtained by using, for example, shells of various crustaceans such as crabs and shrimp as raw materials, and crushing and defibrating them. The chitosan nanofibers can be obtained, for example, by using shells of various crustaceans such as crabs and shrimp as raw materials, crushing them, and deacetylating them by alkali treatment to defibrate them. The biomass nanofibers may be used alone or in combination of two or more having different raw materials, fiber lengths, fiber diameters and the like. The biomass nanofibers preferably contain cellulose nanofibers because they are easily available and have abundant types. The cellulose nanofibers preferably have a fiber diameter in the range of 1 nm or more and 800 nm or less, and more preferably in the range of 1 nm or more and 500 nm or less. Further, the cellulose nanofibers have an aspect ratio preferably in the range of 10 or more and 10000 or less, more preferably in the range of 50 or more and 7500 or less, and further preferably in the range of 100 or more and 5000 or less.

The foamed rubber molded product has a biomass nanofiber content of 10% by mass or less. When the content of the biomass nanofibers in the foamed rubber molded body is 10% by mass or less, the biomass nanofibers are dispersed on the wall of the bubble cell existing inside the foamed rubber molded body as described later, and the elasticity of the bubble cell is obtained. In order to strengthen the wall of the bubble cell while maintaining the property, even if the foam rubber molded body is loaded and deformed, the deformation is difficult to be fixed by the wall of the strengthened bubble cell, and the bubble cell is removed by removing the load. Since it is easy to return to the original size and shape, the sagging caused by the load can be reduced. The biomass nanofiber content of the foam rubber molded product is preferably 8% by mass or less, more preferably 6% by mass or less, and particularly preferably 5% by mass or less. The lower limit of the content of the biomass nanofibers in the foam rubber molded product is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and 0.008% by mass. The above is more preferable, and 0.01% by mass or more is particularly preferable.

Further, in the foamed rubber molded product, the content of the biomass nanofibers may be appropriately selected depending on the use of the foamed rubber. If the biomass nanofiber content of the foamed rubber molded body is 10% by mass or less, a foamed rubber molded body with reduced compression set and less loss of bulk due to use can be obtained, but compression set can be obtained. Applications that require flexibility while reducing, such as underwater clothing such as wet suits, dry suits, and rubber boots with a torso, cushioning materials for vehicles used in various vehicles such as automobiles and railroad vehicles, and various rubber sheets. In the case of rubberized cloth, the biomass nanofiber content of the foamed rubber molded body is preferably 5% by mass or less, more preferably 0.001% by mass or more and 3% by mass or less, and 0.005% by mass or more and 2.5% by mass. The following is more preferable, and 0.008% by mass or more and less than 1% by mass is particularly preferable.

On the other hand, applications where the hardness (hardness) of the foamed rubber molded body and the hardness during compression (compressive stress) are required while reducing the compression set, for example, not only damping vibration and sound, but also hardness and resistance. Anti-vibration rubber and sound-proof rubber used in places where impact resistance is required, and foam rubber as long as it is a sealing material that is required to match the shape even for gaps with complicated shapes and surely prevent the ingress of water etc. The biomass nanofiber content of the molded product is preferably 0.1% by mass or more and 8% by mass or less, more preferably 0.5% by mass or more and 7.5% by mass or less, and further preferably 1% by mass or more and 6% by mass or less. It is particularly preferably 2.5% by mass or more and 5% by mass or less.

As the biomass nanofibers such as the cellulose nanofibers, those in a state of being dispersed in water can be used by utilizing the hydrophilicity thereof from the viewpoint of handleability. Of course, it is also possible to use a solid fine powder. Further, in order to improve the dispersibility when mixed with various rubber components, chemically modified biomass nanofibers may be used, or a coupling agent may be added. The chemically modified biomass nanofiber is not particularly limited, and examples thereof include chemically modified cellulose nanofiber in which an alkanoyl group such as an acetyl group is introduced into a hydroxyl group on the surface of the cellulose nanofiber. The coupling agent is not particularly limited, and for example, a silane coupling agent, another known coupling agent, or the like can be used.

The foamed rubber molded body contains a rubber component which is a main component of the foamed rubber molded body, a vulcanizing agent and a foaming agent in addition to biomass nanofibers. In addition, if necessary, vulcanization accelerator, vulcanization aid, vulcanization retarder (also referred to as anti-burning agent, retarder), anti-aging agent, antioxidant, ozone deterioration inhibitor, processing aid, softening It can contain agents, fillers, flame retardants, antistatic agents and the like. The vulcanization agent, vulcanization accelerator, vulcanization aid, foaming agent, processing aid, softener, filler, reinforcing agent and the like are not particularly limited, and known ones can be appropriately used.

The vulcanizing agent used for the foamed rubber molded product is not particularly limited, and known ones can be used. Examples of the sulphurizing agent include sulfur (there are types such as powdered sulfur, precipitated sulfur, colloidal sulfur, and surface-treated sulfur), inorganic sulphurizing agents such as sulfur chloride, sulfur dichloride, selenium, and tellurium, and morpholindisulfide. , Sulfur-containing organic compounds such as alkylphenol disulfide, hydrotalcites, magnesium oxide, trilead tetraoxide, iron trioxide, metal oxide-based sulphurizers such as titanium dioxide, and resin-based sulphurizers such as alkylphenol resins and modified alkylphenol resins. Agents, polyamine-based sulfurizing agents such as hexamethylenediaminecarbamate, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, peroxydicarbonates and other peroxides. Sulfur agent (also referred to as peroxide-based cross-linking agent, PO sulphurizing agent, PO cross-linking agent, peroxide sulfurizing agent, peroxide cross-linking agent), p-quinonedioxime, p, p'-dibenzoylquinone. Examples thereof include quinoid-based sulfurizing agents such as dioxime (also referred to as quinoid-based sulfurizing agents, quinoid-based cross-linking agents, and quinoid-based cross-linking agents). These vulcanizing agents may be appropriately selected and used according to the rubber component. When chloroprene rubber is used as the rubber component in the foamed rubber molded body according to the embodiment of the present invention, it is preferable to use a metal oxide-based vulcanizing agent as the vulcanizing agent.

The content of the vulcanizing agent in the foamed rubber molded body according to the embodiment of the present invention is not particularly limited and can be adjusted according to the intended use. For example, 0.1 mass by mass with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 25 parts by mass or more, 0.5 parts by mass or more and 20 parts by mass or less, or 1 part by mass or more and 15 parts by mass or less. It may be added in proportions.

The sulfide accelerator is not particularly limited, but is, for example, aldehyde ammonia-based, aldehyde amine-based, guanidine-based, thiourea-based (also referred to as thiourea-based compound or thiourea-based compound), thiazole-based, and thiuram-based. (Also referred to as a thiuram-based compound), dithioate-based, xanthate-based, sulfenamide-based (also referred to as sulfenamide-based compound) and the like can be mentioned. The guanidine-based vulcanization accelerator is not particularly limited, and for example, N, N'-diphenylguanidine and N, N'-diolttolylguanidine can be used. The thiourea-based vulcanization accelerator is not particularly limited, and for example, ethylene thiourea (2-mercaptoimidazoline), N, N'-diethylthiourea, trimethylthiourea, N, N'-dibutylthiourea and the like can be used. Can be done. The thiuram-based sulfide accelerating agent is not particularly limited, and is, for example, dipentamethylene thiuram tetrasulfide, tetramethylthiuram monosulfide (TS), tetramethylthiuram disulfide (TT), tetraethylthiuram disulfide (TTD), and tetrabutyl. Thiram disulfide (TBTD), tetrabenzyl thiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide and the like can be used. The xanthate-based vulcanization accelerator is not particularly limited, but for example, xanthate salt and its derivatives can be used. The sulfenamide-based vulcanization accelerator is not particularly limited, but for example, N-cyclohexyl-2-benzothiazolyl sulfenamide (CZ), Nt-butyl-2-benzothiazolyl sulfenamide ( NS), N-oxydiethylene-2-benzothiazolyl sulfenamide, N, N-diisopropyl-2-benzothiazolyl sulfenamide, N, N-dicyclohexyl-2-benzothiazolyl sulfenamide, etc. should be used. Can be done. The vulcanization accelerator may be used alone or in combination of two or more.

The content of the vulcanization accelerator in the foamed rubber molded product according to the embodiment of the present invention is not particularly limited and can be appropriately adjusted depending on the intended use. For example, 0. It may be added in a ratio of 1 part by mass or more and 10 parts by mass or less, or may be added in a ratio of 0.2 parts by mass or more and 5 parts by mass or less, and 0.3 parts by mass or more and 3 parts by mass. It may be added in a proportion of less than a portion.

The vulcanization aid is not particularly limited, but is, for example, a vulcanization aid for metal oxides such as zinc oxide, lead tan, and calcium oxide, various fatty acids such as stearic acid, oleic acid, and zinc stearate, and metal salts thereof. , Triethanolamine, diethylene glycol and the like. The vulcanization aid may be used alone or in combination of two or more. The content of the vulcanization aid is not particularly limited in the foamed rubber molded body according to the embodiment of the present invention, but the ratio is, for example, 0.1 part by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 0.5 parts by mass or more and 20 parts by mass or less, or may be added in a ratio of 1 part by mass or more and 15 parts by mass or less.

In the foamed rubber molded body of one embodiment of the present invention, an additive for vulcanization, that is, a vulcanization agent, a vulcanization accelerator, and a vulcanization aid can be used depending on the production method and the use of the obtained foamed rubber molded body. It can be adjusted and used as appropriate. The foamed rubber molded body of one embodiment of the present invention contains vulcanization additives, that is, a vulcanization agent, a vulcanization accelerator, and a vulcanization aid in total, by 0.1 mass with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 5 parts or more and 50 parts by mass or less, or may be added in a ratio of 0.5 parts by mass or more and 40 parts by mass or less, or 1 part by mass or more and 30 parts by mass or less. It may be added so as to be in the ratio of.

The processing aid is added in order to improve the processability when various additives are added to the rubber component as a raw material and kneaded. Examples of the processing aid include higher fatty acids, metal salts of higher fatty acids, fatty acid esters, fatty acid amides, sulfur factices, sulfur chloride factis, sulfur factices made from hydrogenated rapeseed oil, white vaseline, paraffin wax and the like. Examples of the higher fatty acid include palmitic acid, stearic acid, oleic acid and the like. The processing aid may be used alone or in combination of two or more. The content of the processing aid is not particularly limited in the foamed rubber molded body according to the embodiment of the present invention, but the ratio is, for example, 0.1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 0.25 parts by mass or more and 30 parts by mass or less, or may be added in a proportion of 0.5 parts by mass or more and 25 parts by mass or less.

The softening agent is not particularly limited, and for example, paraffin oil other than chlorinated paraffin, naphthen oil, phosphoric acid ester oil other than chlorinated phosphoric acid ester compound, ester oil, petroleum resin, vegetable oil, and the like. Examples thereof include liquid rubber, dioctyl phthalate (DOP), dioctyl sebacate (DOS), and dioctyl azelate (DOZ). The softener may be used alone or in combination of two or more. The content of the softening agent in the foamed rubber molded body according to the embodiment of the present invention is not particularly limited, but is added so as to be, for example, in a ratio of 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 10 parts by mass or more and 55 parts by mass or less, or may be added in a proportion of 12 parts by mass or more and 50 parts by mass or less.

In the foamed rubber molded body of one embodiment of the present invention, processing additives, that is, processing aids and softeners may be appropriately adjusted and used according to the manufacturing method and the intended use of the obtained foamed rubber molded body. can. The foamed rubber molded body according to the embodiment of the present invention contains processing additives, that is, processing aids and softeners in a total ratio of 5 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 10 parts by mass or more and 85 parts by mass or less, or it may be added in a proportion of 12 parts by mass or more and 75 parts by mass or less.

The filler or the reinforcing agent is not particularly limited, and examples thereof include light calcium carbonate, carbon black (CB), white carbon, talc, barium sulfate, magnesium carbonate, and mica. These may be used alone or in combination of two or more. In the foamed rubber molded body of one embodiment of the present invention, the content of the filler and / or the reinforcing agent is not particularly limited, but is, for example, 3 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 5 parts by mass or more and 70 parts by mass or less, or 8 parts by mass or more and 60 parts by mass or less. good.

In one embodiment of the present invention, when an additive is added to a rubber component to form a rubber composition, a foaming agent is also added and kneaded, and when the obtained rubber composition is pressurized and heated, the foaming agent foams. By doing so, it becomes a foamed rubber molded body.

The foaming agent is not particularly limited, and for example, various organic foaming agents can be used in addition to inorganic foaming agents such as sodium hydrogen carbonate and ammonium carbonate. In the foamed rubber molded product of the present invention, it is preferable to use an organic foaming agent.

The organic foaming agent is not particularly limited, and a known organic foaming agent can be used. Examples of the organic foaming agent include a nitroso-based foaming agent, an azo-based foaming agent, a hydrazide-based foaming agent, and the like.

The nitroso-based foaming agent is not particularly limited, but for example, N, N'-dinitrosopentamethylenetetramine or the like can be used. As the N, N'-dinitrosopentamethylenetetramine, "Cellular D (registered trademark)" manufactured by Eiwa Kasei Kogyo Co., Ltd., Sponge Paste No. 4 manufactured by Ouchi Shinko Kasei Kogyo Co., Ltd., and Sankyo Kasei Co., Ltd. Commercially available products such as "Cellmic (registered trademark) A" can be used.

The azo-based foaming agent is not particularly limited, but for example, diazoaminebenzene, azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate and the like can be used. Examples of the azo-based foaming agent include "Vinihole (registered trademark) AC" and "Vinihole (registered trademark) AZ" manufactured by Eiwa Kasei Kogyo Co., Ltd., and "Uniform (registered trademark) AZ" manufactured by Otsuka Chemical Co., Ltd. Commercially available products such as "Cellmic (registered trademark) C" manufactured by Sankyo Kasei Co., Ltd. can be used.

The hydrazide-based foaming agent is not particularly limited, and for example, p, p'-oxybisbenzenesulfonyl hydrazide, benzenesulfonylhydrazide, toluenesulfonylhydrazide, hydrazodicarboxylicamide and the like can be used. Examples of the hydrazide-based foaming agent include "Cermic (registered trademark) S, SX, SX-H" manufactured by Sankyo Kasei Co., Ltd. and "Neo Cerbon (registered trademark)" manufactured by Eiwa Kasei Kogyo Co., Ltd. In the foamed rubber molded product of one embodiment of the present invention, it is preferable to use a hydrazide-based foaming agent.

The foaming agent may be used alone or in combination of two or more.

The content of the foaming agent in the foamed rubber molded body of one embodiment of the present invention is not particularly limited, but is added so as to be, for example, in a ratio of 3 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the rubber component. It may be added in a proportion of 5 parts by mass or more and 20 parts by mass or less, or may be added in a proportion of 7 parts by mass or more and 15 parts by mass or less.

The foamed rubber molded body of the present invention contains biomass nanofibers in a proportion of 10% by mass or less. The method of adding the biomass nanofibers to the foamed rubber molded body is not particularly limited, and for example, if the biomass nanofibers are in the form of powder or in a dried state, they become the main component of the foamed rubber molded body. It may be added directly to the rubber component and kneaded with the rubber component, or when an aqueous dispersion in which the biomass nanofibers are dispersed in water (for example, a gel-like dispersion) is used, the water of the biomass nanofibers is used. A master batch containing a high concentration of biomass nanofibers is prepared using the dispersion liquid and the rubber component that is the main component of the foamed rubber molded body, and the obtained master batch of the biomass nanofibers is used as the main component of the foamed rubber molded body. It may be added to the rubber component.

In the foam rubber molded body, the method of adding the biomass nanofibers is not particularly limited, but the biomass nanofibers are often provided as an aqueous dispersion, for example, a gel-like dispersion, and the biomass nanofibers agglomerate. Since it is easy to carry out, it is preferable to prepare a master batch containing biomass nanofibers at a high concentration, and then add and knead the rubber component which is the main component of the foam rubber molded body.

By producing a foamed rubber molded body using a masterbatch containing biomass nanofibers, the obtained foamed rubber molded body facilitates uniform dispersion of biomass nanofibers inside the foamed rubber molded body. The method for producing a master batch containing biomass nanofibers is not particularly limited, but as will be described later, an aqueous dispersion of biomass nanofibers, for example, a gel-like dispersion and various rubber latexes are mixed and solidified while being dried. When the master batch obtained by the above is used, the dispersed state of the biomass nanofibers is good, which is preferable.

In one embodiment of the present invention, the foamed rubber molded body is obtained by mixing and solidifying a rubber component, a latex containing the same type of rubber component as the rubber component, and an aqueous dispersion of biomass nanofibers. It can be produced by vulcanizing and foaming a rubber composition containing a master batch of fibers, a vulcanizing agent and a foaming agent. When a plurality of rubbers are used as the rubber component in the foamed rubber molded body, the rubber component of the master batch containing the biomass nanofibers is not particularly limited, but the type of rubber having the highest content in the foamed rubber molded body to be manufactured. It is preferable to use a latex containing the same type of rubber component as the component. That is, when producing a foamed rubber molded body mainly composed of chloroprene rubber, it is preferable to produce and add a master batch containing biomass nanofibers using a latex containing chloroprene rubber, and mainly natural rubber. When producing a foam rubber molded product, it is preferable to produce and add a master batch containing biomass nanofibers using a latex containing natural rubber. If the rubber component having the highest content in the obtained foamed rubber molded body and the rubber component of the latex used when manufacturing the master batch are of the same type, in the kneading step when manufacturing the foamed rubber molded body, When the rubber component that is the raw material of the foamed rubber molded body and the rubber component that composes the master batch are easily mixed, the biomass nanofibers are easily dispersed uniformly, and the reinforcing effect of the biomass nanofibers is easily exhibited in the foamed rubber molded body. Conceivable.

The content of the biomass nanofibers contained in the masterbatch of the biomass nanofibers is not particularly limited. That is, since the biomass nanofibers need only be uniformly dispersed in the master batch, when a master batch containing the biomass nanofibers is manufactured using a latex in which the biomass nanofibers are easily dispersed, for example, a latex of natural rubber, the above-mentioned The content of the biomass nanofibers contained in the master batch may be 0.1% by mass or more and 50% by mass or less, or 0.5% by mass or more and 30% by mass or less. The ratio may be 1% by mass or more and 25% by mass or less. On the other hand, when a master batch containing biomass nanofibers is produced using a latex such as a latex of chloroprene rubber in which biomass nanofibers are difficult to disperse, the content of the biomass nanofibers contained in the master batch is 0.1 mass by mass. It may be a ratio of% or more and 18% by mass or less, a ratio of 0.5% by mass or more and 15% by mass or less, or a ratio of 1% by mass or more and 12% by mass or less. The ratio may be 3% by mass or more and 9% by mass or less.

On the other hand, the aqueous dispersion of biomass nanofibers used for producing a master batch containing biomass nanofibers preferably contains biomass nanofibers in a proportion of 0.1% by mass or more and 50% by mass or less. It is more preferably contained in a proportion of 5% by mass or more and 30% by mass or less, particularly preferably to be contained in a proportion of 0.8% by mass or more and 20% by mass or less, and to be contained in a proportion of 1% by mass or more and 15% by mass or less. Most preferred.

The rubber composition is, if necessary, a vulcanization accelerator, a vulcanization aid, a vulcanization retarder, an antioxidant, an antioxidant, an ozone deterioration inhibitor, a processing aid, a softening agent, a filler, and reinforcement. It can contain agents, flame retardants, antistatic agents and the like. As the vulcanizing agent, foaming agent, vulcanization accelerator, vulcanization aid, processing aid, softener and filler, the above-mentioned ones can be used.

The rubber composition can be kneaded using a kneader or the like. The kneaded rubber composition is vulcanized and foamed at high temperature and high pressure to obtain a foamed rubber molded product. In the vulcanization foaming step, the temperature, pressure, and treatment time are not particularly limited, but from the viewpoint of processability and manufacturing cost, the temperature is in the range of 100 ° C. or higher and 200 ° C. or lower, and the pressure is in the range of 3 MPa or higher and 25 MPa or lower. The time is preferably in the range of 5 minutes or more and 60 minutes or less. More preferably, the temperature is in the range of 110 ° C. or higher and 150 ° C. or lower, the pressure is in the range of 5 MPa or higher and 20 MPa or lower, and the time is in the range of 10 minutes or longer and 45 minutes or lower. Further, the vulcanization foaming may be one-stage foaming or two-stage foaming, but is preferably two-stage foaming.

When the rubber composition containing the biomass nanofibers is vulcanized and foamed at high temperature and high pressure, fine bubbles due to the foaming agent are generated in the rubber matrix. Then, when the bubbles grow, they push away the surrounding rubber matrix to form a bubble cell. As the rubber matrix is pushed away, the biomass nanofibers dispersed in that part are also pushed away to the inner wall of the bubble cell. Therefore, the biomass nanofibers are more densely dispersed in the inner wall of each bubble cell of the obtained foam rubber molded body and the wall thickness between the bubble cells, the wall surface is strengthened, and the foamed rubber molded body is formed. Increases strength.

In one embodiment of the present invention, the foam rubber molded body conforms to JIS K 6767: 1999 and has a 50% compression set of 28% or less measured 30 minutes after the load is removed. In the foamed rubber molded body, as described above, since the biomass nanofibers are dispersed in the inner wall of the bubble cell existing inside the foamed rubber molded body, not only is it difficult to be crushed even if a load is applied to the bubble cell, but also the inner wall. Is strengthened, even if it is deformed by applying a load, the property of returning to the original size and shape is enhanced and the compression set is reduced. In the foam rubber molded product of the present invention, the 50% compression set measured 30 minutes after removing the load is preferably 25% or less, preferably 24% or less, in accordance with JIS K 6767: 1999. Is more preferable, and 23% or less is particularly preferable. Further, the foamed rubber molded product conforms to JIS K 6767: 1999, and the 50% compression set measured 1 hour after the load is removed is preferably 25% or less, preferably 22% or less. More preferably, it is particularly preferably 20% or less, and most preferably 18% or less. As a result, the foamed rubber molded product is less likely to sag or lose its shape, easily return to its original shape by removing the load, and easily maintain its original shape for a long period of time, thereby improving the product life. .. An example of the use of the foam rubber molded body of the present invention is underwater clothing, but due to its small compression set, the underwater clothing can be deformed into the shape of underwater clothing even if it is stored for a long period of time in a folded state. It is thought that the comfort when wearing it will be increased because it is less likely to be distorted and it is easy to return to the original shape when used.

In one embodiment of the present invention, the foamed rubber molded product preferably has an elongation at cutting of 300% or more, more preferably 400% or more, as measured in accordance with JIS K 6251: 2010, 460. % Or more is particularly preferable, and 500% or more is most preferable. As a result, the foamed rubber molded body becomes soft and can be suitably used for cushioning materials for vehicles such as underwater clothing and various vehicles such as automobiles and railroad vehicles, various rubber sheets and rubberized cloths that are required to be easily deformed. can. In the foam rubber molded body, JIS
The upper limit of elongation during cutting measured in accordance with K 6251: 2010 is not particularly limited, but it should be 1000% or less from the viewpoint of maintaining mechanical strength to prevent tearing and breakage during use. Is more preferable, 900% or less is more preferable, 800% or less is particularly preferable, and 750% or less is most preferable.

In one embodiment of the present invention, the foam rubber molded body is used in an application where flexibility is not emphasized, that is, an application in which hardness, impact resistance, durability against vibration, and mechanical strength are required rather than flexibility, for example, anti-vibration rubber. When used for soundproof rubber and various sealing materials, the foamed rubber molded body is JIS.
The elongation at cutting measured according to K 6251: 2010 is preferably 50% or more, more preferably 100% or more, particularly preferably 120% or more, and preferably 150% or more. Most preferred. When the foam rubber molded product of the present invention is used for applications where hardness, impact resistance, durability against vibration, and mechanical strength are required, the upper limit of elongation during cutting is also not particularly limited, but is preferably 500% or less. It is more preferably 450% or less, particularly preferably 400% or less, and most preferably 350% or less.

In one embodiment of the present invention, the foam rubber molded product preferably has a 100% tensile stress of 85 kPa or less, more preferably 80 kPa or less, and 75 kPa or less, as measured in accordance with JIS K 6251: 2010. Is more preferable, and 70 kPa or less is particularly preferable. As a result, the foamed rubber molded body becomes soft and can be suitably used for cushioning materials for vehicles such as underwater clothing and various vehicles such as automobiles and railroad vehicles, various rubber sheets and rubberized cloths that are required to be easily deformed. can. In the foam rubber molded product of the embodiment, the lower limit of 100% tensile stress measured in accordance with JIS K6251: 2010 is not particularly limited, but 5 kPa from the viewpoint of maintaining strength during use or usability. It may be more than 10 kPa or more.

In one embodiment of the present invention, when the foamed rubber molded body is used in an application in which flexibility is not emphasized, that is, in an application in which hardness, impact, durability against vibration, and mechanical strength are required rather than flexibility, the foamed rubber molded body is said to be foamed. The 100% tensile stress measured according to JIS K 6251: 2010 is preferably larger than 85 kPa, more preferably 90 kPa or more, particularly preferably 100 kPa or more, and 120 kPa or more. Is most preferable. As a result, the foamed rubber molded body becomes moderately hard, and can be suitably used for applications where strength and hardness are required, for example, vibration-proof rubber, sound-proof rubber, and various sealing materials. In the foam rubber molded product of the embodiment, the upper limit of the 100% tensile stress measured according to JIS K 6251: 2010 is not particularly limited, but is preferably 800 kPa or less, more preferably 750 kPa or less. It is preferably 700 kPa or less, and particularly preferably 700 kPa or less.

In one embodiment of the present invention, the foamed rubber molded body preferably has a 25% compressive stress of 40 kPa or less, more preferably 30 kPa or less, and 25 kPa or less, measured in accordance with JIS K 6767: 1999. Is particularly preferable, and 22 kPa or less is most preferable. As a result, the foamed rubber molded body is easily deformed, and it is used for cushioning materials for vehicles such as underwater clothing, automobiles and railroad vehicles, which are required not to hinder movement when worn, various rubber sheets and rubberized cloth. It can be suitably used. In the foam rubber molded product, the lower limit of the 25% compressive stress measured in accordance with JIS K 6767: 1999 is not particularly limited, but from the viewpoint of maintaining strength during use or usability, 5 kPa.
The above is preferable, 8 kPa or more is more preferable, 10 kPa or more is particularly preferable, and 12 kPa or more is most preferable.

In one embodiment of the present invention, when the foamed rubber molded body is used in an application in which flexibility is not emphasized, that is, in an application in which hardness, impact, durability against vibration, and mechanical strength are required rather than flexibility, foamed rubber is used. The 25% compressive stress measured in accordance with JIS K 6767: 1999 is preferably 10 kPa or more, more preferably 15 kPa or more, particularly preferably 20 kPa or more, and 30 kPa or more. Is the most preferable. As a result, the foamed rubber molded body becomes moderately hard, and can be suitably used for applications where strength and hardness are required, for example, vibration-proof rubber, sound-proof rubber, and various sealing materials. In the foam rubber molded product of the embodiment, the upper limit of the 25% compressive stress measured in accordance with JIS K 6767: 1999 is not particularly limited, but is preferably 150 kPa or less, more preferably 130 kPa or less. It is particularly preferably 125 kPa or less, and most preferably 120 kPa or less.

Even when the foamed rubber molded body is used for applications requiring flexibility, for example, cushioning materials for vehicles used for various vehicles such as underwater clothing, automobiles and railroad vehicles, various rubber sheets and rubberized cloths. , Some strength is required to prevent damage during use. When the foam rubber molded product of the present invention is used in an application in which flexibility is important, the tensile strength measured in accordance with JIS K 6251: 2010 is preferably 200 kPa or more, and more preferably 250 kPa or more. It is particularly preferable that it is 300 kPa or more, and most preferably 350 kPa or more. As a result, the foamed rubber molded product has excellent mechanical strength. In the foam rubber molded product, the upper limit of the tensile strength measured in accordance with JIS K 6251: 2010 is not particularly limited, but it is 900 kPa or less from the viewpoint of maintaining the strength during use or the feeling of use. It is preferably 850 kPa or less, more preferably 800 kPa.
The following is particularly preferable, and 750 kPa or less is most preferable.

In one embodiment of the present invention, when the foamed rubber molded body is used in an application in which flexibility is not emphasized, that is, in an application in which hardness, impact, durability against vibration, and mechanical strength are required rather than flexibility, foamed rubber is used. The formed body preferably has a tensile strength of 300 kPa or more, more preferably 400 kPa or more, particularly preferably 450 kPa or more, and most preferably 500 kPa or more, as measured in accordance with JIS K 6251: 2010. As a result, the foamed rubber molded body becomes moderately hard, and can be suitably used for applications where strength and hardness are required, for example, vibration-proof rubber, sound-proof rubber, and various sealing materials. In the foam rubber molded product, the upper limit of the tensile strength measured in accordance with JIS K6251: 2010 is not particularly limited, but is preferably 1700 kPa or less, more preferably 1500 kPa or less, and 1300 kPa or less. It is particularly preferable to have 1200 kPa or less, and most preferably 1200 kPa or less.

In the foamed rubber molded body of one embodiment of the present invention, the tensile strength measured according to JIS K 6251: 2010 is based on JIS K 6251: 2010 depending on the application in which the foamed rubber molded body is used. It is also possible to set the value in consideration of the balance with the measured elongation at the time of cutting. For example, applications that require high elasticity and strength that does not cause damage during use, such as underwater clothing such as wet suits, cushioning materials for vehicles used in various vehicles such as automobiles and railroad vehicles, various rubber sheets and rubber. When used for pulling cloth, the elongation at cutting is preferably 300% or more and 1000% or less, and the tensile strength is preferably 200 kPa or more and 900 kPa or less, and the elongation at cutting is 400% or more and 900% or less. It is more preferable that the tensile strength is 250 kPa or more and 850 kPa or less, the elongation at the time of cutting is 460% or more and 800% or less, and the tensile strength is 300 kPa or more and 800 kPa or less, and the cutting is particularly preferable. It is most preferable that the hourly elongation is 500% or more and 750% or less, and the tensile strength is 350 kPa or more and 750 kPa or less.

On the other hand, in one embodiment of the present invention, the foamed rubber molded body is used for applications such as anti-vibration rubber, sound-proof rubber, and various sealing materials that require high hardness and high tensile strength while having a certain degree of flexibility. If there is, it is preferable that the elongation at cutting is 50% or more and 500% or less and the tensile strength is 300 kPa or more and 1700 kPa or less, and the elongation at cutting is 100% or more and 450% or less and the tensile strength is said. It is more preferable that the elongation is 400 kPa or more and 1500 kPa or less, the elongation at cutting is 120% or more and 400% or less, and the tensile strength is 450 kPa or more and 1300 kPa or less, and the elongation at cutting is 150% or more. It is most preferably 350% or less and the tensile strength is 500 kPa or more and 1200 kPa or less.

The foamed gom molded product according to the embodiment of the present invention preferably has a hardness of less than 40, preferably 30 or less, as measured by a rubber hardness meter (Durometer) CSC2 type manufactured by Polymer Meter Co., Ltd. It is more preferable, and it is particularly preferable that it is 25 or less. As a result, the foamed rubber molded body has excellent elasticity and flexibility, and is flexible such as cushioning materials for vehicles used for various vehicles such as underwater clothing, automobiles and railroad vehicles, various rubber sheets and rubberized cloth. It can be suitably used for applications requiring properties. When the foamed rubber molded body of the present invention is used for the above-mentioned use, that is, for a purpose requiring flexibility, the lower limit of the hardness measured by the ASKER® rubber hardness tester (Durometer) CSC2 type manufactured by Polymer Meter Co., Ltd. is particularly low. Although not limited to, it may be 5 or more, 8 or more, or 10 or more.

On the other hand, in one embodiment of the present invention, when the foamed rubber molded body is used for an application in which hardness, mechanical strength, load, impact, and durability against vibration are required, ASKER (registered trademark) manufactured by Polymer Meter Co., Ltd. is used. It is preferable that the hardness measured by a rubber hardness meter (durometer) CSC2 type is 40 or more. When the hardness of the foamed rubber molded body is 40 or more measured by ASKER® rubber hardness tester (Durometer) CSC2 type manufactured by Polymer Meter Co., Ltd., ASKER (registered trademark) manufactured by Polymer Meter Co., Ltd. ) Rubber hardness tester (durometer)
Hardness may be measured using a C type. In one embodiment of the present invention, when the foamed rubber molded body is used for applications requiring hardness, mechanical strength, load, impact, and vibration resistance, ASKER (registered trademark) rubber hardness manufactured by Polymer Meter Co., Ltd. is required. The hardness measured using a total (durometer) C type is preferably 8 or more and 70 or less, more preferably 10 or more and 60 or less, and particularly preferably 15 or more and 50 or less.

The density of the foamed rubber molded product is not particularly limited because it depends on the type of rubber component contained in the foamed rubber molded product. However, considering the lightness of the obtained foamed rubber molded body, the density of the foamed rubber molded body has an apparent density of 0.30 g / cm measured in accordance with JIS K 7222: 2005, which is applied mutatis mutandis in JIS K 6767: 1999. It is preferably ³ or less, more preferably 0.25 g / cm ³ or less, particularly preferably 0.20 g / cm ³ or less, and most preferably 0.18 g / cm ³ or less. As a result, the foam rubber molded body becomes lighter, and when used for underwater clothing, the lightness increases, which reduces the burden on the wearer, enables long-term work, and reduces wearer's fatigue. To do. In addition, in cushioning materials for vehicles, vibration-proof rubber, soundproof rubber, and various sealing materials used for various vehicles such as automobiles and railroad vehicles, the apparent density is reduced, which reduces the weight of the members and contributes to the weight reduction of the entire vehicle. Can be done.

In one embodiment of the present invention, the foamed rubber molded body preferably has a thermal conductivity of 0.05 W / (m · K) or less measured in accordance with JIS A 1412-1: 2016. It is more preferably 048 W / (m · K) or less. As a result, the heat insulating property of the foam rubber molded product is improved, and the heat retaining property is enhanced when used for underwater clothing or the like, so that the comfort in underwater work in winter or long-term underwater work is enhanced. When used as a cushioning material for vehicles, vibration-proof rubber, sound-proof rubber, and various sealing materials used for various vehicles such as automobiles and railroad vehicles, the heat insulating property is similarly improved, so that the heat retention and heat insulating properties of the internal space are improved. ..

In one embodiment of the present invention, the foamed rubber molded body is a rubber-based material having a relatively high tensile strength, and is used for applications in which a rubber-based material having excellent flexibility and flexibility is required, for example, bending of a joint portion. Underwater clothing that is required to be easy to put on and take off, anti-vibration rubber, soundproof rubber, cushioning material for vehicles, complicated shapes that are required to highly efficiently attenuate vibration and sound energy and maintain airtightness. It can be suitably used for a sealing material that is required to match the shape with respect to a gap and surely prevent the ingress of water or the like, or for various rubber sheets or rubber pulling cloths that make use of the flexibility of foamed rubber.

In one embodiment of the present invention, the underwater clothing may be composed of the foam rubber molded product alone. Alternatively, in one embodiment of the present invention, the underwater clothing may be formed by laminating a foam rubber molded body and a cloth such as a jersey cloth. The foamed rubber molded body has high elongation at cutting, low 100% tensile stress, and low 50% compression set, so that it has excellent flexibility and is less likely to lose its shape even if it is greatly deformed. Further, since the foamed rubber molded body has the tensile strength required for underwater clothing, low hardness, low specific density, and high flexibility, it is easy to put on and take off, and workability in water is improved. Further, since the foamed rubber molded body has a low thermal conductivity, it is excellent in heat insulating property and heat retaining property, and it is easy to work even at a low water temperature.

The underwater clothing is not particularly limited as long as it covers at least a part of the body when working underwater. For example, in addition to wet suits and dry suits, rubber boots with a torso (also called a torso length or a wader) that covers the lower body to the chest can be mentioned.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

(Preparation of masterbatch of cellulose nanofibers)
Using an aqueous dispersion of cellulose nanofibers consisting of 5% by mass of cellulose nanofibers and 95% by mass of water (cellulose nanofibers manufactured by Sugino Machine Co., Ltd. "trade name BiNFi-s (registered trademark), product number: FMa-10005"). , 142 parts by mass of the aqueous dispersion of the cellulose nanofibers and 168.9 parts by mass of a chloroprene rubber latex (commercially available chloroprene rubber latex consisting of 55% by mass of chloroprene rubber and 45% by mass of water) are mixed, stirred and solidified. And then dried to give a master batch of cellulose nanofibers. The obtained masterbatch of cellulose nanofibers contains 7.1% by mass of cellulose nanofibers and 92.9% by mass of chloroprene rubber.

(Example 1)
The sulfur-modified type chloropre rubber, the masterbatch of the cellulose nanofibers prepared above, and other additives were mixed at the blending ratios shown in Table 1 below, and kneaded for 60 minutes using a kneader.

The obtained rubber composition was aged at room temperature for 24 hours and then extruded with an extruder to obtain an unvulcanized sheet. The unvulcanized sheet was placed in a mold heated to 125 ° C., press-vulcanized for 15 minutes while pressurizing (pressure 10 MPa) with a press machine, and foamed (primary vulcanization). Next, it was placed in a mold heated to 165 ° C., press-vulcanized for 15 minutes while being pressurized (pressure 10 MPa) with a press machine, and foamed (secondary vulcanization) to obtain a foamed rubber molded body.

(Examples 2 to 3)
The same as in Example 1 except that the blending amount of the sulfur-modified type chloroprene rubber used in Example 1 and the masterbatch of the cellulose nanofibers produced above was set to the ratio shown in Table 1 below. A foamed rubber molded product was obtained.

(Comparative Example 1)
A foamed rubber molded product was obtained in the same manner as in Example 1 except that the masterbatch of cellulose nanofibers was not added and the blending amount of the additive was set to the ratio shown in Table 1 below with respect to the chloroprene rubber.

(Comparative Example 2)
The masterbatch used in Examples 1 to 3 is prepared with respect to 142 parts by mass of the same aqueous dispersion of cellulose nanofibers used in producing the masterbatch of the cellulose nanofibers used in Examples 1 to 3. 51.6 parts by mass of the same chloroprene latex used in the above step was mixed, stirred and solidified, and then dried to obtain a masterbatch of cellulose nanofibers. The master batch of the cellulose nanofibers was obtained containing 20% by mass of the cellulose nanofibers and 80% by mass of the chloroprene rubber, but the cellulose nanofibers may have a poor dispersion, and the cellulose nanofibers may have a poor dispersion. No foamed rubber molded body was obtained in which the cellulose was uniformly dispersed without agglomeration.

The physical characteristics of the foam rubber molded products obtained in Examples 1 to 3 and Comparative Example 1 were measured as follows, and the results are shown in Table 1 below.

(Elongation when cutting)
Measured according to JIS K 6251: 2010. Specifically, in accordance with JIS K 6251: 2010, a dumbbell-shaped No. 2 test piece (100 mm × 25 mm × 10 mm) is fixed to a constant-speed tensile tester so that the tensile speed becomes 500 ± 50 mm / min. The length of the sample when the test piece was cut (the length between the chucks used to fix the sample) was measured, and the elongation during cutting of the sample was calculated from the length of the original sample piece.

(100% tensile stress)
Measured according to JIS K 6251: 2010. Specifically, in accordance with JIS K 6251: 2010, a dumbbell-shaped No. 2 test piece (100 mm × 25 mm × 10 mm) is fixed to a constant-speed tensile tester so that the tensile speed becomes 500 ± 50 mm / min. The value of the tensile stress when the test piece was 100% stretched was measured and used as 100% tensile stress.

(50% compression set)
Measured according to JIS K 6767: 1999. Specifically, in accordance with JIS K 6767: 1999, first, a test piece (20 mm × 20 mm × 5 mm) was prepared at room temperature (23 ± 2 ° C.), and the initial thickness (T ₀ ) was measured. Next, a load was applied to a state in which the initial thickness (T ₀ ) was distorted by 50%, that is, a state in which the thickness became half of the initial thickness, and the mixture was compressed and left for 22 hours. After compressing for 22 hours, the compression is released by removing the load, the thickness (T _{30 m} ) 30 minutes after releasing the compression (after removing the load), and after releasing the compression (load). The thickness (T _1h ) after 1 hour (after removal) was measured using a dial thickness gauge, respectively, and the 50% compression set was calculated by the following formula.
After 30 minutes 50% compression set (%) = [(T ₀ -T _30m ) / T ₀ ] x 100
1 hour later 50% compression set (%) = [(T ₀ -T _1h ) / T ₀ ] x 100

(25% compressive stress)
Measured according to JIS K 6767: 1999. Specifically, in accordance with JIS K 6767: 1999, the test piece (20 mm × 20 mm × 20 mm) is compressed at a compression rate of 10 mm / min, and at 25% strain, that is, the thickness of the sample is the original thickness. The compressive stress at 75% was measured.

(Tensile strength)
Measured according to JIS K 6251: 2010. Specifically, in accordance with JIS K 6251: 2010, a dumbbell-shaped No. 2 test piece (100 mm x 25 mm x 10 mm) is fixed to a constant-speed tensile tester so that the tensile speed is 500 ± 50 mm / min. The value of the tensile strength when the test piece was cut was measured and used as the tensile strength.

(hardness)
It was measured with a durometer "ASKER (registered trademark) rubber hardness tester CSC2 type" manufactured by Polymer Meter Co., Ltd. Specifically, a portion having a thickness of 10 mm or more and 20 mm or less of the test piece was selected, and the hardness was measured at that location. When the thickness of the test pieces was less than 10 mm, the test pieces were overlapped and adjusted so that the thickness was within the above range. At this time, the number of test pieces to be stacked was set to 3 or less.

(Apparent density)
Measurements were made in accordance with JIS K 7222: 2005, which is applied mutatis mutandis in JIS K 6767: 1999.

(Thermal conductivity)
Measured according to JIS A 1412-1: 2016.

As can be seen from the results in Table 1 above, the foamed rubber molded bodies of Examples 1 to 3 containing the rubber component and the biomass nanofibers and having the content of the biomass nanofibers of 10% by mass or less were subjected to 50% compression set (50% compression set). After 30 minutes), it was significantly reduced as compared with the foamed rubber molded body containing no biomass nanofibers. In Example 3 containing 0.035% by mass of biomass nanofibers, the value of 50% compression set (after 30 minutes) was 50% compression set (after 30 minutes) in the foamed rubber molded body of Comparative Example 1 containing no biomass nanofibers. It is 70% (30% decrease) of the value after 30 minutes), and Example 1 containing 0.92% by mass of biomass nanofibers and Example 2 containing 3.03% by mass of biomass nanofibers are biomass nanofibers. Compared with the 50% compression set (after 30 minutes) in the foamed rubber molded body containing no fiber, the value was reduced by nearly 50%. Since it was confirmed that the compression set was significantly reduced by 50% in both Example 1 and Example 2 in which the amount of the biomass nanofibers added was different, the foamed rubber molded body contained the biomass nanofibers and thus foamed rubber molding. It was found that the bubble cells inside the body were strengthened and a significant reduction in compression set was achieved. Since the values of elongation at cutting, hardness, and tensile stress are completely different between Example 1 and Example 2 due to the difference in the content of biomass nanofibers, the content of biomass nanofibers can be appropriately adjusted. It was found that the compression set was reduced and a foamed rubber molded body having mechanical properties suitable for each application could be obtained. In particular, in Example 1 in which the content of the biomass nanofibers was less than 1% by mass, the value of the 50% compression set (after 30 minutes) was that of Comparative Example 1 in which the foamed rubber molded body did not contain the biomass nanofibers. Not only is it about half (16%) of the value of the 50% compression set in the foamed rubber molded body, but also the tensile strength is 540 kPa or more and the elongation at the time of cutting is 500% or more. It was found that the foamed rubber molded body had good mechanical strength and excellent flexibility.

On the other hand, the foam rubber molded product of Comparative Example 1 containing no biomass nanofibers has a 50% compression set (after 30 minutes) of about 30%, and when deformed by applying a long-term load, the foamed rubber molded body is deformed even if the load is removed. There was sagging that was maintained and reduced in bulk.

In addition, from the results of Comparative Example 2, it was found that when the rubber component contains the biomass nanofibers at a high concentration, the biomass nanofibers tend to aggregate. Although it depends on the dispersibility of the biomass nanofibers with respect to the latex used when preparing the master batch and the rubber component contained in the foamed rubber molded body, the content of the biomass nanofibers in the foamed rubber molded body is 10. If the composition exceeds mass%, aggregation of the biomass nanofibers is likely to occur, and it is presumed that the effect of reducing the compression set cannot be obtained in some cases.

When a wet suit in which a jersey cloth was attached to the foam rubber molded body obtained in Examples 1 and 3 was produced, it was excellent in elasticity and flexibility, was easy to put on and take off, and fit when worn. The sex and motility were also good.

In the foamed rubber molded body of the present invention, the compression set is reduced by containing biomass nanofibers in the foamed rubber molded body at a ratio of 10% by mass or less. Such foamed rubber molded bodies are intended for wet suits, dry suits, underwater clothing such as rubber boots with a torso, and for the purpose of efficiently dampening the energy of vibration and sound, as well as improving fuel efficiency and reducing energy loss. Various anti-vibration rubbers, soundproof rubbers, shock absorbers for vehicles, or rubber packings that are required to match the shape even for gaps with complicated shapes and reliably prevent the ingress of water, oil, etc. It can be used for various sealing materials such as oil seals and water blocking materials, various rubber sheets, and rubberized cloths.

Claims (11)

A foamed rubber molded product containing a rubber component and biomass nanofibers , and further containing at least one of a filler and a reinforcing agent .
The rubber components are natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber, acrylic rubber, epichlorohydrium. It is at least one selected from the group consisting of rubber, chlorosulfonated polyethylene, urethane rubber, silicone rubber and fluororubber.
The content of biomass nanofibers in the foam rubber molded product is 0.005% by mass or more and 2.5% by mass or less.
The content of the filler and / or the reinforcing agent is a ratio of 3 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component in the foamed rubber molded body.
The tensile strength measured in accordance with JIS K 6251: 2010 is 200 kPa or more and 900 kPa or less.
The elongation at cutting measured according to JIS K 6251: 2010 is 400% or more and 1000% or less.
A foam rubber molded product according to JIS K 6767: 1999, wherein the 50% compression set measured 30 minutes after the load is removed is 28% or less. The foam rubber molded product according to claim 1, wherein the 50% compression set is 25% or less, which is measured 1 hour after the load is removed, in accordance with JIS K6 767: 1999. The foam rubber molded product according to claim 1 or 2, wherein the 100% tensile stress measured according to JIS K 6251: 2010 is 85 kPa or less. The foamed rubber molded product according to any one of claims 1 to 3 , wherein the hardness measured by using an ASKER (registered trademark) rubber hardness tester (durometer) CSC2 type manufactured by Polymer Meter Co., Ltd. is less than 40. The foamed rubber molded body further contains at least one of a processing aid and a softening agent, and the content of the processing aid and the softening agent is 10 with respect to 100 parts by mass of the rubber component in total of the processing aid and the softening agent. The foamed rubber molded body according to any one of claims 1 to 4, which has a ratio of 5 parts by mass or more and 85 parts by mass or less. A foamed rubber molded product containing a rubber component and biomass nanofibers , and further containing at least one of a filler and a reinforcing agent .
The rubber component is from isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, butyl rubber, chlorinated butyl rubber, brominated butyl rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, urethane rubber, silicone rubber and fluororubber. At least one selected from the group of
The content of biomass nanofibers in the foam rubber molded product is 2.5% by mass or more and 5% by mass or less.
The content of the filler and / or the reinforcing agent is a ratio of 3 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component in the foamed rubber molded body.
The elongation at cutting measured according to JIS K 6251: 2010 is 50% or more and 350% or less, and the tensile strength measured according to JIS K 6251: 2010 is 300 kPa or more and 1700 kPa or less.
The 100% tensile stress measured according to JIS K 6251: 2010 is larger than 85 kPa and 800 kPa or less.
A foam rubber molded product according to JIS K 6767: 1999, wherein the 50% compression set measured 30 minutes after the load is removed is 28% or less. The foam rubber molded product according to claim 6, wherein the 25% compressive stress measured according to JIS K 6767: 1999 is 20 kPa or more and 150 kPa or less. ASKER (registered trademark) rubber hardness tester (Durometer) manufactured by Polymer Meter Co., Ltd. The hardness measured using CSC2 type is 40 or more, and ASKER (registered trademark) rubber hardness meter (Durometer) C manufactured by Polymer Meter Co., Ltd. The foamed rubber molded product according to claim 6 or 7 , wherein the hardness measured using a mold is 8 or more and 70 or less. The foamed rubber molded body further contains at least one of a processing aid and a softening agent, and the content of the processing aid and the softening agent is 10 with respect to 100 parts by mass of the rubber component in total of the processing aid and the softening agent. The foamed rubber molded body according to any one of claims 6 to 8, which has a ratio of 5 parts by mass or more and 85 parts by mass or less. The method for manufacturing a foamed rubber molded product according to any one of claims 1 to 9.
It contains a rubber component, a master batch of biomass nanofibers obtained by mixing and solidifying a rubber latex of the same type as the rubber component and an aqueous dispersion of biomass nanofibers, a vulcanizing agent and a foaming agent, and further a filler. A method for producing a foamed rubber molded body, which comprises cross-linking and foaming a rubber composition containing at least one of a reinforcing agent and a reinforcing agent to obtain a foamed rubber molded body. The method for producing a foamed rubber molded body according to claim 10, wherein the masterbatch of biomass nanofibers contains 0.1 to 50% by mass of biomass nanofibers.