Foamable composition, foamed article and method for producing the same

Abstract

A foamable composition comprising a chloroprene polymer, a plasticizer, a foaming agent and a peptizer, wherein the content of the filler is 10 parts by mass or less, the content of the plasticizer is 3 parts by mass or more, the content of the foaming agent is 5 parts by mass or more, and the content of the peptizer is 0.1 parts by mass or more, based on 100 parts by mass of the chloroprene polymer. A foamed article of the foamable composition. A method for producing a foamed article, comprising the step of foaming the foamable composition.

Description

Technical Field

[0001] The present invention relates to a foamable composition, a foam, a method for producing the same, and the like. Background Art

[0002] The foam can be used in various applications such as buildings, automobiles, electric equipment, and audio equipment. As a foamable composition for obtaining a foam, a composition containing polypropylene is known (for example, see Patent Document 1 below).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-119089 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The foamable composition for obtaining a foam is required to have a high expansion ratio from the viewpoint of efficiently obtaining a foam having a low specific gravity.

[0008] One aspect of the present invention is to provide a foamable composition having a high expansion ratio. Another aspect of the present invention is to provide a foamed article of such a foamable composition. Another aspect of the present invention is to provide a method for producing such a foamed article.

[0009] Means for solving problems

[0010] One aspect of the present invention relates to a foamable composition comprising a chloroprene polymer, a plasticizer, a foaming agent and a peptizer, wherein the content of the filler is 10 parts by mass or less, the content of the plasticizer is 3 parts by mass or more, the content of the foaming agent is 5 parts by mass or more, and the content of the peptizer is 0.1 parts by mass or more, based on 100 parts by mass of the chloroprene polymer.

[0011] Such a foamable composition has a high expansion ratio, thereby being able to efficiently obtain a foam having a low specific gravity.

[0012] Another aspect of the present invention relates to a foam of the foamable composition. Another aspect of the present invention relates to a method for producing a foam, comprising the step of foaming the foamable composition.

[0013] Effects of the Invention

[0014] According to one aspect of the present invention, a foamable composition having a high expansion ratio can be provided. According to another aspect of the present invention, a foamed article of such a foamable composition can be provided. According to another aspect of the present invention, a method for producing such a foamed article can be provided. DETAILED DESCRIPTION

[0015] Hereinafter, specific embodiments of the present invention will be described in detail. It should be noted that the present invention is not limited to the embodiments described below.

[0016] In this specification, "A or more" in the numerical range refers to A and a range greater than A. "A or less" in the numerical range refers to A and a range less than A. In the numerical ranges recorded in stages in this specification, the upper limit or lower limit of the numerical range of a certain stage can be arbitrarily combined with the upper limit or lower limit of the numerical range of other stages. In the numerical ranges recorded in this specification, the upper limit or lower limit of the numerical range can be replaced by the values ​​shown in the embodiments. The so-called "A or B" includes either A and B, or both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination. Regarding the content of each component in the composition, when there are multiple substances belonging to each component in the composition, unless otherwise specified, it refers to the total amount of the multiple substances present in the composition. The term "process" not only includes independent processes, but also includes this term as long as the desired effect of the process can be achieved when it cannot be clearly distinguished from other processes. The so-called "(meth)acrylic acid" refers to at least one of acrylic acid and its corresponding methacrylic acid. The same applies to other similar expressions such as "(meth)acrylate".

[0017] The foamable composition involved in this embodiment contains a chloroprene polymer, a plasticizer, a foaming agent and a peptizer. In the foamable composition involved in this embodiment, relative to 100 parts by mass of the chloroprene polymer, the content of the filler is 10 parts by mass or less, the content of the plasticizer is 3 parts by mass or more, the content of the foaming agent is 5 parts by mass or more, and the content of the peptizer is 0.1 parts by mass or more. The foamed body involved in this embodiment is a foamed body obtained by foaming the foamable composition involved in this embodiment, and is a foamed body of the foamable composition involved in this embodiment.

[0018] The foamable composition involved in this embodiment has a high foaming ratio. Thus, a foam with low specific gravity can be efficiently obtained. For example, according to the foamable composition involved in this embodiment, when a sheet with a length of 20 mm, a width of 20 mm, and a thickness of 3 mm formed by the foamable composition is foamed at 170°C for 20 minutes and then kept at 25°C for 30 minutes, a foaming ratio of 700% (volume %) or more can be obtained ([(volume after foaming-volume before foaming) / volume before foaming]×100). When the evaluation of the foaming ratio is not the purpose, the foam can be obtained using conditions other than these conditions.

[0019] The above-mentioned expansion ratio may be 750% or more, 800% or more, 850% or more, 900% or more, 950% or more, 1000% or more, or 1050% or more. For example, the expansion ratio may be 1500% or less.

[0020] The chloroprene polymer is a polymer having a structural unit derived from chloroprene (2-chloro-1,3-butadiene) (a polymer having chloroprene as a monomer unit). The chloroprene polymer may be a homopolymer of chloroprene, a copolymer of chloroprene and other monomers copolymerizable with chloroprene, etc. The polymer structure of the chloroprene polymer is not particularly limited.

[0021] From the viewpoint of easily obtaining a high expansion ratio, the content of the structural unit derived from chloroprene may be 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, or 99% by mass or more based on the total mass of the chloroprene polymer. The chloroprene polymer may be in a form composed of structural units derived from chloroprene (a form in which substantially 100% by mass of the chloroprene polymer is structural units derived from chloroprene).

[0022] Examples of monomers copolymerizable with chloroprene include (meth)acrylic acid esters (methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), hydroxyalkyl (meth)acrylates (2-hydroxyethyl (meth)acrylate, 2-hydroxymethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.), 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, ethylene, styrene, acrylonitrile, etc. Other monomers copolymerizable with chloroprene are not limited to one type, and for example, three or more monomers including chloroprene may be copolymerized.

[0023] The chloroprene polymer may be a sulfur-modified chloroprene polymer, a thiol-modified chloroprene polymer, a xanthogen-modified chloroprene polymer, a dithiocarbonate-based chloroprene polymer, a trithiocarbonate-based chloroprene polymer, a urethane-based chloroprene polymer, etc. From the viewpoint of easily obtaining a high expansion ratio, the chloroprene polymer may include a sulfur-modified chloroprene polymer.

[0024] The sulfur-modified chloroprene polymer may not have a structure represented by the following general formula (I) at the molecular end (R 1 represents an alkyl group having 1 to 4 carbon atoms).

[0025] -SC(=S)-OR 1 …(I)

[0026] From the viewpoint of excellent balance between expansion ratio and processability (adhesiveness), the content of the chloroprene polymer may be in the following ranges based on the total mass of the foamable composition (total mass of the solid content, the same below). The content of the chloroprene polymer may be 50% by mass or more, greater than 50% by mass, 55% by mass or more, 60% by mass or more, 65% by mass or more, 67% by mass or more, 68% by mass or more, 69% by mass or more, 70% by mass or more, 71% by mass or more, 72% by mass or more, 73% by mass or more, 74% by mass or more, 75% by mass or more, or 76% by mass or more. The content of the chloroprene polymer may be 90% by mass or less, 85% by mass or less, 80% by mass or less, 79% by mass or less, 78% by mass or less, 77% by mass or less, 76% by mass or less, 75% by mass or less, 74% by mass or less, 73% by mass or less, 72% by mass or less, 71% by mass or less, 70% by mass or less, 69% by mass or less, 68% by mass or less, or 67% by mass or less. From these viewpoints, the content of the chloroprene polymer may be 50 to 90% by mass, 60 to 80% by mass, or 65 to 80% by mass.

[0027] The foamable composition involved in this embodiment may contain a filler or may not contain a filler. Examples of the filler include carbon black, silica, clay, talc, calcium carbonate, etc. The filler may not contain at least one selected from the group consisting of silica, clay, talc and calcium carbonate. From the perspective of easily obtaining a high foaming ratio, the filler may include carbon black.

[0028] Examples of carbon black include furnace black obtained by an incomplete combustion method, thermal black obtained by a thermal decomposition method, channel black, acetylene black, etc. Examples of furnace black include HAF (High Abrasion Furnace Black), SAF (Super Abrasion Furnace Black), ISAF (Intermediate Super Abrasion Furnace Black), IISAF (Intermediate ISAF), MAF (Medium Abrasion Furnace Black), FEF (Fast Extruding Furnace Black), SRF (Semi-Reinforcing Furnace Black), GPF (General Purpose Furnace Black), FF (Fine Furnace Black), CF (Conductive Furnace Black), etc. Thermal black includes FT (Fine Thermal Black), MT (Medium Thermal Black), etc. Channel black includes EPC (Easy Processing Channel Black), MPC (Medium Processing Channel Black), etc. Acetylene black includes ACET (Acetylene Black), etc. From the viewpoint of easily obtaining a high expansion ratio, the carbon black may include HAF.

[0029] From the viewpoint of obtaining a high expansion ratio, the content of the filler is 10 parts by mass or less relative to 100 parts by mass of the chloroprene polymer. From the viewpoint of easily obtaining a high expansion ratio, the content of the filler can be less than 10 parts by mass, less than 8 parts by mass, less than 6 parts by mass, less than 5 parts by mass, less than 4 parts by mass, less than 3 parts by mass, less than 2 parts by mass, or less than 1 part by mass. The content of the filler is 0 parts by mass or more, can be greater than 0 parts by mass, can be 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, 4 parts by mass or more, 5 parts by mass or more, 6 parts by mass or more, or 8 parts by mass or more. From these viewpoints, the content of the filler can be 0 to 10 parts by mass, greater than 0 parts by mass and less than 10 parts by mass, greater than 0 parts by mass and less than 5 parts by mass, greater than 0 parts by mass and less than 2 parts by mass, or 1 to 5 parts by mass. From the same viewpoint, the content of carbon black can be the above-mentioned ranges relative to 100 parts by mass of the chloroprene polymer.

[0030] The content of the filler can be the following range based on the gross mass of the foamable composition. From the viewpoint of easily obtaining a high expansion ratio, the content of the filler can be 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.8% by mass or less, 0.75% by mass or less, 0.72% by mass or less, 0.7% by mass or less, or 0.5% by mass or less. The content of the filler is 0% by mass or more, can be greater than 0% by mass, can be 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 0.72% by mass or more, 0.75% by mass or more, 0.8% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, or 6% by mass or more. From these viewpoints, the content of the filler can be 0 to 10% by mass, greater than 0% by mass and less than 10% by mass, greater than 0% by mass and less than 4% by mass, greater than 0% by mass and less than 1% by mass, or greater than 0% by mass and less than 0.8% by mass. From the same viewpoint, the content of carbon black can be within the above ranges based on the total mass of the foamable composition.

[0031] The foamable composition involved in the present embodiment contains a plasticizer. As the plasticizer, sebacic acid plasticizer, phthalate plasticizer, adipic acid plasticizer (dioctyl adipate (DOA) etc.), ester plasticizer, ether ester plasticizer, thioether plasticizer, aromatic oil, cycloparaffin oil, vegetable oil (rapeseed oil etc.) etc. can be cited. As the sebacic acid plasticizer, dioctyl sebacate (for example, bis(2-ethylhexyl) sebacate (DOS)), dimethyl sebacate, diethyl sebacate, dibutyl sebacate, diisopropyl sebacate, dioctyl sebacate (dicaprylsebacate) and other sebacic acid derivatives can be cited. From the viewpoint of easily obtaining a high foaming ratio, the plasticizer can include a sebacic acid plasticizer, a sebacic acid derivative, and a bis(2-ethylhexyl) sebacate.

[0032] From the viewpoint of obtaining high expansion ratio, relative to 100 mass parts of chloroprene polymer, the content of plasticizer is more than 3 mass parts.From the viewpoint of easily obtaining high expansion ratio, the content of plasticizer can be more than 5 mass parts, more than 6 mass parts, more than 8 mass parts, more than 10 mass parts, more than 12 mass parts, more than 15 mass parts, more than 18 mass parts, more than 20 mass parts, more than 22 mass parts or more than 25 mass parts.From the viewpoint of easily obtaining excellent processability (adhesiveness), the content of plasticizer can be less than 50 mass parts, less than 48 mass parts, less than 40 mass parts, less than 35 mass parts, less than 30 mass parts, less than 28 mass parts, less than 25 mass parts, less than 22 mass parts, less than 20 mass parts, less than 18 mass parts, less than 15 mass parts, less than 12 mass parts, less than 10 mass parts, less than 8 mass parts, less than 6 mass parts or less than 5 mass parts. From the above viewpoints, the content of the plasticizer may be 3 to 50 parts by mass, 3 to 30 parts by mass, 3 to 25 parts by mass, 5 to 25 parts by mass, 10 to 25 parts by mass, 10 to 20 parts by mass, 10 to 15 parts by mass, 3 to 20 parts by mass, 3 to 10 parts by mass, 5 to 20 parts by mass, or 5 to 10 parts by mass. From the same viewpoints, the content of the sebacic acid derivative may be within the above ranges relative to 100 parts by mass of the chloroprene polymer.

[0033] The content of plasticizer can be the following scope based on the gross mass of foamable composition.From the viewpoint of easily obtaining high expansion ratio, the content of plasticizer can be more than 1 mass %, more than 2 mass %, more than 3 mass %, more than 4 mass %, more than 5 mass %, more than 6 mass %, more than 7 mass %, more than 7.5 mass %, more than 8 mass %, more than 10 mass %, more than 12 mass % or more than 13 mass %.From the viewpoint of easily obtaining excellent processability (adhesiveness), the content of plasticizer can be less than 30 mass %, less than 25 mass %, less than 20 mass %, less than 18 mass %, less than 16 mass %, less than 15 mass %, less than 14 mass %, less than 13 mass %, less than 12 mass %, less than 10 mass %, less than 8 mass %, less than 7.5 mass %, less than 7 mass %, less than 6 mass %, less than 5 mass % or less than 4 mass %. From these viewpoints, the content of the plasticizer can be 1-30 mass%, 2-30 mass%, 2-20 mass%, 3-20 mass%, 3-10 mass%, 5-20 mass%, 5-15 mass%, or 5-10 mass%. The content of the plasticizer can be 14 mass% or more, 15 mass% or more, or 16 mass% or more. From the same viewpoint, the content of the sebacic acid derivative can be the above-mentioned ranges based on the total mass of the foamable composition.

[0034] The foamable composition involved in this embodiment contains a foaming agent. Examples of the foaming agent include organic foaming agents, inorganic foaming agents (sodium bicarbonate, ammonium carbonate, etc.), etc. From the perspective of easily obtaining a high foaming ratio, the foaming agent may include an organic foaming agent.

[0035] Examples of the organic foaming agent include hydrazide foaming agents, nitroso foaming agents, azo foaming agents, etc. From the viewpoint of easily obtaining a high expansion ratio, the organic foaming agent may include a hydrazide foaming agent.

[0036] Examples of hydrazide foaming agents include p,p'-oxybisbenzenesulfonylhydrazide (4,4'-Oxybisbenzenesulfonohydrazide), benzenesulfonylhydrazide, toluenesulfonylhydrazide, hydrazodicarbonamide, etc. Examples of nitroso foaming agents include N,N'-dinitrosopentamethylenetetramine, etc. Examples of azo foaming agents include diazobenzene, azodicarbonamide, azobisisobutyronitrile, and barium azodicarboxylate.

[0037] From the viewpoint of obtaining a high expansion ratio, the content of the foaming agent is 5 parts by mass or more relative to 100 parts by mass of the chloroprene polymer. From the viewpoint of easily obtaining a high expansion ratio, the content of the foaming agent can be 6 parts by mass or more, 8 parts by mass or more, 10 parts by mass or more, 12 parts by mass or more, 15 parts by mass or more, 18 parts by mass or more, or 20 parts by mass or more. The content of the foaming agent can be 30 parts by mass or less, 25 parts by mass or less, 20 parts by mass or less, 18 parts by mass or less, 15 parts by mass or less, 12 parts by mass or less, 10 parts by mass or less, or 8 parts by mass or less. From these viewpoints, the content of the foaming agent can be 5 to 30 parts by mass, 5 to 25 parts by mass, 5 to 20 parts by mass, 5 to 15 parts by mass, 5 to 10 parts by mass, 10 to 25 parts by mass, 10 to 20 parts by mass, or 10 to 15 parts by mass. From the same viewpoint, the content of the organic foaming agent may be within the above-mentioned respective ranges, and the content of the hydrazide foaming agent may be within the above-mentioned respective ranges, based on 100 parts by mass of the chloroprene polymer.

[0038] The content of the foaming agent can be the following range based on the total mass of the foamable composition. From the viewpoint of easily obtaining a high expansion ratio, the content of the foaming agent can be 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more, 7% by mass or more, 7.5% by mass or more, 8% by mass or more, 10% by mass or more, 12% by mass or more, or 13% by mass or more. The content of the foaming agent can be 20% by mass or less, 15% by mass or less, 13% by mass or less, 12% by mass or less, 10% by mass or less, 8% by mass or less, 7.5% by mass or less, 7% by mass or less, 6% by mass or less, 5% by mass or less, or 4% by mass or less. From these viewpoints, the content of the foaming agent can be 1-20% by mass, 3-20% by mass, 3-15% by mass, 3-10% by mass, 5-15% by mass, 5-10% by mass, 6-10% by mass, or 6-8% by mass. From the same viewpoint, the content of the organic foaming agent based on the total mass of the foamable composition may be within the above-mentioned respective ranges, and the content of the hydrazide foaming agent may be within the above-mentioned respective ranges.

[0039] The foamable composition involved in the present embodiment contains a plasticizer. The plasticizer can have the effect of cutting the molecular chain of the polymer component, and can also have the effect of acting as a vulcanization accelerator. As a plasticizer, dithiocarbamate compounds such as pentamethylene dithiocarbamate piperidinium salt (PPD, piperidinium piperidine-1-carbodithioate), zinc diethyl dithiocarbamate, zinc dibutyl dithiocarbamate, and sodium dibutyl dithiocarbamate can be cited; thiuram compounds such as tetramethylthiuram disulfide and tetraethylthiuram disulfide; 2,2'-dibenzamide diphenyl disulfide compounds; thiazole compounds; xanthate compounds; imidazole compounds, etc. From the perspective of easily obtaining a high foaming ratio, the plasticizer can include dithiocarbamate compounds.

[0040] From the viewpoint of obtaining high expansion ratio, relative to 100 mass parts of chloroprene polymer, the content of peptizer is more than 0.1 mass parts. From the viewpoint of easily obtaining high expansion ratio, the content of peptizer can be more than 0.2 mass parts, more than 0.3 mass parts, more than 0.5 mass parts, more than 0.8 mass parts, more than 1 mass parts, more than 1.2 mass parts, more than 1.5 mass parts, more than 1.8 mass parts, more than 2 mass parts, more than 2.5 mass parts or more than 3 mass parts. From the viewpoint of easily obtaining excellent processability (adhesiveness), the content of peptizer can be less than 10 mass parts, less than 8 mass parts, less than 5 mass parts, less than 3 mass parts, less than 2.5 mass parts, less than 2 mass parts, less than 1.8 mass parts, less than 1.5 mass parts, less than 1.2 mass parts, less than 1 mass parts, less than 0.8 mass parts, less than 0.5 mass parts, less than 0.3 mass parts or less than 0.2 mass parts. From these viewpoints, the content of the peptizer may be 0.1 to 10 parts by mass, 0.1 to 3 parts by mass, 0.1 to 2 parts by mass, 0.1 to 1 part by mass, 0.2 to 3 parts by mass, 0.2 to 2 parts by mass, 0.2 to 1 part by mass, 0.5 to 3 parts by mass, 1 to 3 parts by mass, 0.5 to 2 parts by mass, 0.5 to 1 part by mass, or 1 to 2 parts by mass. From the same viewpoint, the content of the dithiocarbamate compound may be within the above ranges relative to 100 parts by mass of the chloroprene polymer.

[0041] The content of peptizer can be the following scope based on the gross mass of foamable composition.From the viewpoint of easily obtaining high expansion ratio, the content of peptizer can be more than 0.01 mass %, more than 0.03 mass %, more than 0.05 mass %, more than 0.07 mass %, more than 0.1 mass %, more than 0.3 mass %, more than 0.4 mass %, more than 0.5 mass %, more than 0.7 mass %, more than 1 mass %, more than 1.2 mass % or more than 1.5 mass %.From the viewpoint of easily obtaining excellent processability (adhesiveness), the content of peptizer can be less than 5 mass %, less than 4 mass %, less than 3 mass %, less than 2.5 mass %, less than 2 mass %, less than 1.8 mass %, less than 1.5 mass %, less than 1.2 mass %, less than 1 mass %, less than 0.7 mass %, less than 0.5 mass %, less than 0.4 mass %, less than 0.3 mass % or less than 0.1 mass %. From these viewpoints, the content of the peptizer can be 0.01-5 mass%, 0.05-5 mass%, 0.05-3 mass%, 0.1-3 mass%, 0.1-2.5 mass%, 0.1-2 mass%, 0.1-1.5 mass%, 0.1-1 mass%, 0.4-3 mass%, 0.5-3 mass%, 0.4-2 mass%, 0.4-1 mass%, 0.5-1 mass%, or 0.6-0.8 mass%. The content of the peptizer can be 1.8 mass% or more, or 2 mass% or more. From the same viewpoint, the content of the dithiocarbamate compound can be the above-mentioned ranges based on the total mass of the foamable composition.

[0042] The foamable composition involved in this embodiment may contain a vulcanizing agent. Examples of the vulcanizing agent include sulfur, zinc oxide (ZnO), magnesium oxide (MgO), lead oxide, lead tetraoxide, iron trioxide, titanium dioxide, calcium oxide, hydrotalcite and other inorganic compounds. From the viewpoint of easily obtaining a high foaming ratio, the vulcanizing agent may include at least one selected from the group consisting of zinc oxide and magnesium oxide.

[0043] The content of the vulcanizing agent can be the following range relative to 100 parts by mass of the chloroprene polymer. The content of the vulcanizing agent can be greater than 0 parts by mass, and from the viewpoint of easily obtaining a high expansion ratio, it can be 0.1 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, 4 parts by mass or more, 5 parts by mass or more, 6 parts by mass or more, 7 parts by mass or more, 8 parts by mass or more, or 9 parts by mass or more. From the viewpoint of easily obtaining a high expansion ratio, the content of the vulcanizing agent can be 20 parts by mass or less, 15 parts by mass or less, 12 parts by mass or less, 10 parts by mass or less, or 9 parts by mass or less. From these viewpoints, the content of the vulcanizing agent can be greater than 0 parts by mass and less than 20 parts by mass, greater than 0 parts by mass and less than 10 parts by mass, or 5 to 10 parts by mass.

[0044] The content of the vulcanizing agent can be in the following ranges based on the total mass of the foamable composition. The content of the vulcanizing agent can be greater than 0 mass %, and from the viewpoint of easily obtaining a high foaming ratio, it can be 0.1 mass % or more, 0.5 mass % or more, 1 mass % or more, 2 mass % or more, 3 mass % or more, 4 mass % or more, 5 mass % or more, or 6 mass % or more. From the viewpoint of easily obtaining a high foaming ratio, the content of the vulcanizing agent can be 20 mass % or less, 15 mass % or less, 10 mass % or less, 8 mass % or less, 7 mass % or less, or 6 mass % or less. From these viewpoints, the content of the vulcanizing agent can be greater than 0 mass % and less than 20 mass %, greater than 0 mass % and less than 10 mass %, or 3 to 8 mass %.

[0045] The foamable composition of the present embodiment may contain a vulcanization accelerator. Examples of the vulcanization accelerator include thiourea compounds such as ethylene thiourea, diethyl thiourea, trimethyl thiourea, triethyl thiourea, N,N'-diphenyl thiourea, and N,N'-diethyl thiourea; and guanidine compounds such as 1,3-diphenylguanidine. From the perspective of easily obtaining a high foaming ratio, the vulcanization accelerator may include at least one selected from the group consisting of ethylene thiourea and guanidine.

[0046] The content of the vulcanization accelerator can be the following range relative to 100 parts by mass of the chloroprene polymer. The content of the vulcanization accelerator can be greater than 0 parts by mass, and from the viewpoint of easily obtaining a high expansion ratio, it can be more than 0.1 parts by mass, more than 0.5 parts by mass, more than 1 part by mass, more than 2 parts by mass, more than 3 parts by mass, more than 4 parts by mass, or more than 5 parts by mass. From the viewpoint of easily obtaining a high expansion ratio, the content of the vulcanization accelerator can be less than 10 parts by mass, less than 8 parts by mass, less than 7 parts by mass, less than 6 parts by mass, or less than 5 parts by mass. From these viewpoints, the content of the vulcanization accelerator can be greater than 0 parts by mass and less than 10 parts by mass.

[0047] The content of the vulcanization accelerator can be the following range based on the total mass of the foamable composition. The content of the vulcanization accelerator can be greater than 0 mass %, and from the viewpoint of easily obtaining a high foaming ratio, it can be 0.1 mass % or more, 0.5 mass % or more, 1 mass % or more, 2 mass % or more, or 3 mass % or more. From the viewpoint of easily obtaining a high foaming ratio, the content of the vulcanization accelerator can be 10 mass % or less, 8 mass % or less, 6 mass % or less, 5 mass % or less, or 4 mass % or less. From these viewpoints, the content of the vulcanization accelerator can be greater than 0 mass % and 10 mass % or less.

[0048] As components other than the above components, the foamable composition involved in the present embodiment may contain additives such as resin components (excluding chloroprene polymers), rubber components (excluding chloroprene polymers), lubricants, antioxidants, surfactants, emulsion stabilizers, viscosity modifiers, antioxidants, preservatives, etc. The foamable composition involved in the present embodiment may not contain organic peroxides. The content of organic peroxides may be less than 1 part by mass or less than 0.1 part by mass relative to 100 parts by mass of chloroprene polymers. The foamable composition involved in the present embodiment may not contain chlorinated paraffin. The content of chlorinated paraffin may be less than 5 parts by mass or less than 1 part by mass relative to 100 parts by mass of chloroprene polymers.

[0049] As the resin component, there can be mentioned ethylene·α-olefin·non-conjugated polyene copolymer, poly(alkylphenol) polysulfide, etc. The content of ethylene·α-olefin·non-conjugated polyene copolymer can be less than 3 parts by mass or less than 1 part by mass relative to 100 parts by mass of chloroprene polymer. The content of poly(alkylphenol) polysulfide can be less than 1 part by mass or less than 0.1 part by mass relative to 100 parts by mass of chloroprene polymer. The foaming composition involved in this embodiment may not contain a water-absorbent resin as a resin component. The content of the water-absorbent resin can be less than 10 parts by mass or less than 1 part by mass relative to 100 parts by mass of chloroprene polymer.

[0050] Examples of the rubber component include natural rubber, isoprene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber and other diene rubbers; butyl rubber, ethylene-propylene rubber and other non-diene rubbers, etc. From the viewpoint of improving adhesion to metal plates with oil attached, the rubber component may include butyl rubber.

[0051] From the viewpoint of improving adhesion and easily obtaining a high foaming ratio, the content of the rubber component can be the following range relative to 100 parts by mass of the chloroprene polymer. The content of the rubber component can be 0.1 parts by mass or more, 0.5 parts by mass or more, 1 parts by mass or more, 3 parts by mass or more, 5 parts by mass or more, 8 parts by mass or more, or 10 parts by mass or more. The content of the rubber component can be 100 parts by mass or less, 80 parts by mass or less, 50 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, or 10 parts by mass or less. From these viewpoints, the content of the rubber component can be 0.1 to 100 parts by mass, 1 to 50 parts by mass, or 5 to 20 parts by mass.

[0052] By using a lubricant, the foamable composition can be easily peeled off from a roll, a molding die, a screw of an extruder, etc. when the foamable composition is kneaded. Examples of the lubricant include fatty acids such as stearic acid; alkane-based processing aids such as paraffin; and fatty acid amides. The content of the lubricant may be 0.5 to 5 parts by mass relative to 100 parts by mass of the chloroprene polymer.

[0053] Examples of the anti-aging agent include amine-based anti-aging agents, imidazole-based anti-aging agents, metal carbamates, phenol-based anti-aging agents, and ozone-resistant anti-aging agents (e.g., N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine). Examples of the amine-based anti-aging agent include octylated diphenylamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. The content of the anti-aging agent may be 1 to 10 parts by mass relative to 100 parts by mass of the chloroprene polymer.

[0054] The Mooney viscosity (ML) of the foamable composition according to the present embodiment is 1+4 , 100°C) can be in the following range. From the viewpoint of easily obtaining excellent processability (adhesiveness), the Mooney viscosity can be greater than 0, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 11 or more. From the viewpoint of easily obtaining a high foaming ratio, the Mooney viscosity can be 20 or less, 15 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less. From these viewpoints, the Mooney viscosity can be 0 to 20. As the content of the filler increases, the Mooney viscosity of the foamable composition tends to increase. As the content of the plasticizer or peptizer increases, the Mooney viscosity of the foamable composition tends to decrease.

[0055] The foamable composition according to the present embodiment can be obtained by kneading the above-mentioned components. As a kneading device, a mixer, a Banbury mixer, a kneader mixer, a twin roll, etc. can be used.

[0056] The foam involved in this embodiment may have continuous bubbles formed by hollow cells connected to each other. The continuous bubbles contain multiple hollow cells. The so-called "continuous bubbles" refers to a structure in which at least a portion of the bubbles formed in the foam are continuous. The foam may have a continuous bubble structure or a semi-continuous and semi-independent bubble structure. The continuous bubble structure refers to a structure in which the continuous bubble rate is 100%. In the semi-continuous and semi-independent bubble structure, the lower limit of the continuous bubble rate is greater than 0%, and can be greater than 10%. In the semi-continuous and semi-independent bubble structure, the upper limit of the continuous bubble rate is less than 100%, and can be less than 98%.

[0057] The foamed body involved in the present embodiment can be a single layer. The foamed body involved in the present embodiment can have physical properties suitable for various uses in a single layer state. The foamed body involved in the present embodiment can be suitably used in buildings, automobiles, railway vehicles, aircraft, electrical equipment, audio equipment, audio facilities, etc., and can constitute components (thermal insulation materials, impact absorbing materials, vibration-proof materials, sound absorbing materials, etc.) used in these uses.

[0058] The hardness (Asker F hardness) of the foam body involved in this embodiment can be 1 to 50. Here, the hardness of the foam body can be measured by the following steps. Use a rubber hardness meter (manufactured by Kobunsu Keiki Co., Ltd., trade name: Asker Rubber Hardness Meter F Type) and gently place a disc-shaped pressurized surface on the foam body. The hardness of the foam body is measured by reading the value using the dead weight of the hardness meter as the measurement pressure.

[0059] The method for producing a foamed article according to the present embodiment includes a foaming step of foaming the foamable composition according to the present embodiment. In the foaming step, the foamable composition may be heated for foaming. The temperature for heating and foaming may be, for example, 100 to 220°C.

[0060] Example

[0061] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0062] <Production of Foam>

[0063] Using a mixing mill using an 8-inch roll (manufactured by Nippon Roll MFG. Co., Ltd., roll temperature: 40° C.), in accordance with JIS K 6299, 100 parts by mass of a chloroprene polymer (sulfur-modified, manufactured by Denka Co., Ltd., trade name: DenkaChloroprene PM-40, a polymer not having a structure represented by the above general formula (I)), a filler (carbon black (HAF), manufactured by Asahi Carbon Co., Ltd., trade name: Asahi #70), a plasticizer (bis(2-ethylhexyl) sebacate (DOS), manufactured by Shin Nippon Chemical Co., Ltd., trade name: Sanso Cizer DOS), and a foaming agent (p,p′-oxybisbenzenesulfonylhydrazide (OBSH), manufactured by Sankyo Chemical Co., Ltd., trade name: Cellmic S), a peptizer (pentamethylene dithiocarbamic acid piperidinium salt (PPD), manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name: Nocceler PPD), 1 part by mass of stearic acid (lubricant, manufactured by Kao Corporation, trade name: Lunac S-70V), 3 parts by mass of paraffin (lubricant, manufactured by Nippon Seiro Co., Ltd., trade name: Paraffin Wax-135), 1 part by mass of octylated diphenylamine (antiaging agent, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name: NOCRAC AD-F), 4 parts by mass of magnesium oxide (vulcanizing agent, MgO, manufactured by Kyowa Chemical Industry Co., Ltd., trade name: KYOWAMAG 150), and 5 parts by mass of zinc oxide (vulcanizing agent, ZnO, manufactured by Sakai Chemical Industry Co., Ltd., trade name: Zinc Oxide 2) were kneaded to obtain a foamable composition (composite). Tables 1 and 2 show the amounts of the chloroprene polymer, filler, plasticizer, foaming agent, and peptizer in each of the Examples and Comparative Examples.

[0064] <Evaluation>

[0065] The foamable composition was used to evaluate processability (roll sticking), Mooney viscosity, and expansion ratio.

[0066] (Processability)

[0067] After winding 400 g of the foamable composition on an 8-inch open roll, the processability was evaluated under the conditions of a cooling water temperature of 40° C. and a roll gap of 2.0 mm. The case where the adhesion to the roll was weak and the composition was easily peeled off from the roll by cutting with a roll knife was evaluated as “A”, the case where the adhesion to the roll was slightly strong and the composition needed to be strongly peeled off from the roll by cutting with a roll knife was evaluated as “B”, and the case where the adhesion to the roll was very strong and the composition could not be peeled off from the roll after cutting with a roll knife was evaluated as “C”.

[0068] (Mooney viscosity)

[0069] In accordance with JIS K 6300-1 of Japanese Industrial Standards, the Mooney viscosity (ML) of the foamable composition was measured using a Mooney viscosity tester (manufactured by Shimadzu Corporation, trade name: SMV-301) with an L-shaped rotor under the test conditions of a test temperature of 100° C., a preheating time of 1 minute, and a test time of 4 minutes. 1+4 ) for determination.

[0070] (Foaming ratio)

[0071] Using the above-mentioned foamable composition, a sheet with a thickness of 3 mm is made using an open roller. A test sample with a length of 20 mm, a width of 20 mm, and a thickness of 3 mm is cut from the sheet. The test sample is placed on a release sheet and placed in a gear oven (gearoven) at 170°C for 20 minutes to foam it, thereby obtaining a foam. The foam is taken out of the gear oven, kept at 25°C for 30 minutes, and then the dimensions (length, width and thickness) of the foam are measured using a vernier caliper. The foaming ratio [unit: %] is calculated using the following formula based on the volume change before and after foaming. A foaming ratio of 700% or more is judged to be good.

[0072] Expansion ratio = [(volume after foaming - volume before foaming) / volume before foaming] × 100

[0073] [Table 1]

[0074]

[0075] [Table 2]

[0076]

Claims

1. A foamable composition comprising a chloroprene polymer, a plasticizer, a foaming agent and a peptizer, The plasticizer comprises a sebacic acid derivative, The foaming agent comprises a hydrazide foaming agent, With respect to 100 parts by mass of the chloroprene polymer, the content of the filler is 2 parts by mass or less, the content of the plasticizer is 3 to 15 parts by mass, the content of the foaming agent is 5 parts by mass or more, and the content of the peptizer is 0.1 parts by mass or more.

2. The foamable composition according to claim 1, wherein The chloroprene polymer includes a sulfur-modified chloroprene polymer.

3. The foamable composition according to claim 1 or 2, wherein The filler includes carbon black.

4. The foamable composition according to claim 1 or 2, wherein The content of the filler is greater than 0 parts by mass and not more than 2 parts by mass based on 100 parts by mass of the chloroprene polymer.

5. The foamable composition according to claim 1 or 2, wherein The peptizer includes a dithiocarbamate compound.

6. The foamable composition according to claim 1 or 2, wherein The content of the peptizer is 0.1 to 2 parts by mass relative to 100 parts by mass of the chloroprene polymer.

7. A foamed product of the foamable composition according to any one of claims 1 to 6. 8 . A method for producing a foam, comprising the step of foaming the foamable composition according to claim 1 .

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