JP4843934B2 - Thermoplastic foam having improved heat insulation and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a thermoplastic resin foam having improved heat insulation, comprising a styrene resin and a nitrile resin, and a method for producing the same.

  A method for continuously producing a foam by melting a thermoplastic resin typified by a styrenic resin with an extruder or the like, then adding a foaming agent, cooling it, and extruding it into a low pressure region has already been made. Are known. In addition, a method using a halogenated hydrocarbon such as an aliphatic hydrocarbon, a chlorinated hydrocarbon, a fluorinated hydrocarbon, a chlorine / fluorinated hydrocarbon or the like as a blowing agent is also known.

  In such a thermoplastic resin foam, in order to obtain a foam with low thermal conductivity and excellent heat insulation, the thermal conductivity as a gas is low as a foaming agent, and thermoplastics such as styrene resin are used. It is necessary to use a compound having low permeability to the resin, that is, a compound that is difficult to escape from the bubbles of the foam and difficult to dissipate.

  Examples of such blowing agents include chlorine and / or fluorinated halogenated hydrocarbons, that is, chlorofluorocarbons, hydrochlorofluorocarbons, and the like. In recent years, halogenated hydrocarbons such as chlorofluorocarbon and hydrochlorofluorocarbon have an ozone depleting action, and it is desired to replace them if possible from the viewpoint of protecting the ozone layer. Therefore, as a foaming agent having no ozone destructive action (so-called ozone depletion coefficient is 0), aliphatic hydrocarbons such as propane and butane, hydrofluorocarbons such as 1,1,1,2-tetrafluoroethane or the like A styrenic resin foam using a mixture of these and a method for producing the same have been proposed (see, for example, Patent Documents 1 to 3).

  Furthermore, the present inventors, in a styrene resin foam using an aliphatic hydrocarbon such as propane and butane as a foaming agent, have high flame retardancy specified by JIS A9511 and three types of extruded polystyrene foam heat insulating plates. We have proposed a technique that can achieve both high heat insulation (see, for example, Patent Documents 4 to 6).

  However, such a styrene resin foam is highly permeable to styrene resin immediately after production, and has a higher thermal conductivity than aliphatic hydrocarbons and halogenated hydrocarbons used as blowing agents. Comes into the foam bubbles relatively quickly. Even aliphatic hydrocarbons and halogenated hydrocarbons having low permeability to the styrene resin gradually dissipate from the foam. Therefore, there is a problem that the thermal conductivity of the styrenic resin foam itself is gradually increased, and the heat insulating property is gradually decreased.

In order to prevent air intrusion, for example, in a thermoplastic polymer foam, in order to reduce gas permeation, a method of uniformly dispersing a gas barrier resin in a continuous polymer layer is proposed, and polystyrene or the like is used as a thermoplastic polymer. Technology using ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, acrylonitrile-methyl acrylate copolymer, polyvinylidene fluoride, polyamide, etc. as gas barrier resin, foaming composition including foaming composition and film forming additive A method of mixing a thermoplastic resin and a gas barrier substance, such as a technique relating to a method of manufacturing an insulating foam having a thermal conductivity of less than 0.029 W / mK in which a foam is foamed and an inner surface of a cell is covered with a coating material Has been proposed (E.g., Patent Document 7 or 8).
In addition, a styrenic foam containing a foaming agent with low thermal conductivity has a volume ratio of 45% by volume or less, and the entire surface is covered with a film having a small nitrogen permeability coefficient without any gaps to provide a heat insulating material. In addition, a non-halogen foaming agent is used and a coating of a non-halogen substance that is flame resistant and gas barrier is formed on the surface of a styrene resin extruded foam that does not contain a halogen additive. There has been proposed a method of laminating a gas barrier material on the foam surface, such as a technique that achieves both heat insulation and combustion resistance while using a low foaming agent (see, for example, Patent Documents 9 to 11).
JP-A-7-53761 JP-A-10-237210 JP-A-9-104780 JP 2001-121596 A JP 2001-131322 A JP 2001-131323 A JP-A-5-5050634 JP-A-8-319365 Japanese Patent Laid-Open No. 7-239087 JP 2002-144497 A JP 58-162337 A

  However, JP-A-5-5050634 discloses polystyrene as a thermoplastic resin, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, acrylonitrile-methyl acrylate copolymer, polyvinylidene fluoride, polyamide, etc. as a gas barrier resin. Although the permeability of nitrogen or chlorodifluoromethane (HCFC-22) to the film using the film is described, the thermal conductivity and the change in the actual foam are not described at all. JP-A-8-319365 discloses a thermoplastic resin, but only details about phenol formaldehyde resin, and there is no detailed description about thermoplastic resin such as polystyrene.

  Therefore, the present inventors use a gas barrier resin such as polystyrene and ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyacrylonitrile and copolymer, polyvinylidene fluoride, polyamide, and the like, and a fat such as butane as a blowing agent. As a result of attempts to produce foams using aromatic hydrocarbons, ethylene-vinyl alcohol copolymers and ethylene-vinyl acetate copolymers are poorly compatible with polystyrene and cause exfoliation in foamed molded articles. Due to poor hydrogen solubility, there is a problem that good foam cannot be obtained, such as poor foam moldability, difficult to obtain low density foam, and difficult to obtain foam with high closed cell ratio. I understood. There is a problem that this problem becomes more noticeable as the content of the gas barrier resin is increased. Originally required for polystyrene foam, low density, low thermal conductivity, high closed cell ratio, heat insulation, light weight, etc. It was found that the characteristics such as excellent resistance cannot be exhibited at all.

  In the method of coating a styrene resin foam with a resin having a high gas barrier property as proposed in JP-A-58-162337, JP-A-7-239087, etc., For example, there is a problem that heat insulation performance cannot be maintained due to holes or cracks in the coating film caused by metal fittings such as nails and pins when constructed in a house as a heat insulating material.

  Under such circumstances, the problem to be solved by the present invention is a foaming agent that has low air infiltration and low thermal conductivity as a gas without impairing the heat insulation properties, lightness and other properties of the styrene resin foam. It is an object of the present invention to provide a thermoplastic resin foam with improved heat insulation and a method for producing the same, in which the dissipation of heat is suppressed, thereby suppressing an increase in thermal conductivity.

As a result of intensive studies for solving the above-mentioned problems, the present inventors have used a nitrile resin among the gas barrier resins, so that the foam moldability is good and the density is as low as 10 to 200 kg / m ^3. It has been found that a foam having a high density and closed cell ratio can be obtained. Furthermore, by using a foaming agent having a low thermal conductivity as a gas and having a low permeability to the styrene resin and / or nitrile resin, a foam having a low thermal conductivity, that is, a high heat insulating property can be obtained. And it discovered that the time-dependent change of thermal conductivity was also suppressed, and came to complete this invention.

That is, the present invention is a thermoplastic resin foam formed by extruding and foaming a thermoplastic resin composed of a styrene resin and a nitrile resin, and a thermoplastic resin composition containing a foaming agent, the nitrile resin However, (meth) acrylonitrile and (meth) acrylic acid alkyl ester are graft copolymerized in the presence of a conjugated diene rubber-like polymer, and (meth) acrylonitrile containing 50% by weight or more of a component derived from (meth) acrylonitrile -(Meth) acrylic acid alkyl-butadiene copolymer, and as the blowing agent, a compound having one or more polarities selected from the group consisting of ethers, alcohols and water, hydrocarbons, halogenated hydrocarbons And one or more compounds selected from the group consisting of carbon dioxide and a foam density of 10 kg / m. ^The present invention relates to a thermoplastic resin foam characterized by being ³ or more and 200 kg / m ³ or less.

As a preferred embodiment,
( 1 ) The thermoplastic resin is composed of 30% by weight or more and 99.5% by weight or less of styrene resin and 0.5% by weight or more and 70% by weight or less of nitrile resin,
( 2 ) The residual foaming agent contained in the thermoplastic resin foam is one or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0. ,
( 3 ) One or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0 are selected from the group consisting of saturated hydrocarbons and hydrofluorocarbons having 3 to 5 carbon atoms. It is one or two or more selected compounds,
( 4 ) The amount of the remaining foaming agent contained in the thermoplastic resin foam is 0.1 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin foam.
It relates to the thermoplastic resin foam described above.

In the second aspect of the present invention, a thermoplastic resin composition containing a foaming agent in a thermoplastic resin composed of a styrene resin and a nitrile resin that are heated and melted is extruded and foamed in a low pressure region to foam a thermoplastic resin. In the presence of a conjugated diene rubber-like polymer, graft copolymerization of (meth) acrylonitrile and (meth) acrylic acid alkyl ester is used as the nitrile resin, and is derived from (meth) acrylonitrile. (Meth) acrylonitrile- (meth) acrylic acid alkyl-butadiene copolymer containing 50% by weight or more of the component to be used, and at least one polarity selected from the group consisting of ethers, alcohols and water as a blowing agent a compound having a hydrocarbon, it in combination with one or more compounds selected from the group consisting of halogenated hydrocarbons and carbon dioxide Relates to a method for producing a thermoplastic resin foam, characterized in that.

As a preferred embodiment,
(1) A thermoplastic resin comprising 30% by weight or more and 99.5% by weight or less of a styrene resin and 0.5% by weight or more and 70% by weight or less of a nitrile resin is used as the thermoplastic resin.
( 2 ) One or more compounds selected from the group of hydrocarbons and halogenated hydrocarbons and having an ozone depletion coefficient of 0 are used as the foaming agent other than the polar compound. ,
(3) One or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0 are selected from the group consisting of saturated hydrocarbons and hydrofluorocarbons having 3 to 5 carbon atoms. It is one or two or more selected compounds,
The present invention relates to a method for producing the thermoplastic resin foam described above.

According to the present invention, a foam having a good foam moldability of a thermoplastic resin composed of a styrene resin and a nitrile resin, a low density of 10 to 200 kg / m ³ , and a high closed cell ratio can be obtained. Furthermore, by using a foaming agent having a low thermal conductivity as a gas and a low permeability to styrene-based resins and / or nitrile-based resins, it is highly heat-insulating and has a thermal conductivity with time. There are provided a thermoplastic resin foam in which a change in temperature is suppressed and a method for producing the same. The thermoplastic resin foam of the present invention is useful for various uses, particularly for the use of heat insulating materials for buildings, from the viewpoint of its excellent heat insulating properties.

  The thermoplastic resin used as the base material of the thermoplastic resin foam of the present invention uses a styrene resin and a nitrile resin in combination.

  The styrenic resin used in the present invention is not particularly limited, and can be obtained from, for example, a styrene homopolymer obtained only from a styrene monomer, a styrene monomer, a monomer copolymerizable with styrene, or a derivative thereof. Specific examples include random, block or graft copolymers, post-brominated polystyrene, modified polystyrene such as rubber-reinforced polystyrene, and the like.

  Examples of the monomer copolymerizable with styrene include styrene such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene. Derivatives, polyfunctional vinyl compounds such as divinylbenzene, (meth) acrylic compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, cyanide such as (meth) acrylonitrile Vinyl compounds, diene compounds such as budadiene or derivatives thereof, polymerizable unsaturated fatty acids such as itaconic acid, maleic acid, fumaric acid, crotonic acid, cinnamic acid, N-methylmaleimide, N-ethylmaleimide, N- Maleic acid, maleic anhydride, itaconic anhydride, such as tilmaleimide, N-octylmaleimide, N-isopropylmaleimide, N-phenylmaleimide, NP-bromophenylmaleimide, N-O-chlorophenylmaleimide, N-cyclohexylmaleimide , Unsaturated carboxylic anhydrides such as citraconic anhydride, epoxy group-containing unsaturated compounds such as allyl glycidyl ether and glycidimethacrylate, amino groups such as allylamine, aminoethyl methacrylate, methacrylic acid-aminopropyl, and aminostyrene Containing unsaturated compounds, acrylamide compounds such as acrylamide and N-methylacrylamide, 2-hydroxyethyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxy-2-butene Such as hydroxyl group-containing unsaturated compounds. These may be used alone or in combination of two or more.

  Among the styrenic resins, styrene homopolymer, styrene-acrylonitrile copolymer with an acrylonitrile component of less than 50% by weight, (meth) acrylic acid copolymerized polystyrene, maleic anhydride modified polystyrene, impact polystyrene from the viewpoint of processability. Etc. are preferable. Most preferred is a styrene homopolymer.

  Furthermore, the styrene resin used in the present invention may be a styrene resin having a branched structure for the purpose of adjusting MFR, melt viscosity at the time of molding, melt tension, and the like.

  The styrenic resin used in the present invention may be used alone, or two or more different styrenic resins such as copolymerization component, molecular weight, molecular weight distribution, branched structure, and MFR may be mixed and used.

  The styrenic resin used in the present invention has a melt flow rate (hereinafter referred to as MFR) of 0.1 g / 10 min or more and 50 g / 10 min or less, which is excellent in moldability during extrusion foam molding. It is easy to adjust the discharge amount at the time of molding, the thickness, width, density or closed cell ratio of the obtained thermoplastic resin foam to a desired value, and the foamability of the obtained thermoplastic resin foam (of the foam The easier it is to adjust the thickness, width, density, closed cell ratio, surface properties, etc. to the desired situation, the better the foamability), and the thermoplastic resin foam excellent in appearance etc. can be obtained, and the compressive strength, bending strength or This is preferable from the viewpoint of obtaining a thermoplastic resin foam having a good balance between mechanical strength such as bending deflection and characteristics such as toughness. Further, the MFR of the styrenic resin is more preferably 0.3 g / 10 min or more and 30 g / 10 min or less from the viewpoint of the balance of molding processability and foaming mechanical strength, toughness, etc., and 0.5 g / 10 min. The amount of 20 g / 10 min or less is particularly preferable. In the present invention, MFR is measured according to method A and test condition H of JIS K7210 (1999).

  The nitrile resin used in the present invention is a polymer containing unsaturated nitrile such as acrylonitrile as a main polymerization monomer component. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like. Of these, acrylonitrile and methacrylonitrile are preferred.

  The nitrile resin is not particularly limited, and for example, a resin obtained only from an unsaturated nitrile monomer, an unsaturated nitrile monomer, a monomer copolymerizable with an unsaturated nitrile, or a random derivative obtained therefrom. Specific examples include block or graft copolymers.

  Monomers copolymerizable with unsaturated nitriles include, for example, styrene, methyl styrene, dimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, bromo styrene, dibromo styrene, tribromo styrene, chloro styrene, dichloro styrene, trichloro. Styrene derivatives such as styrene, polyfunctional vinyl compounds such as divinylbenzene, diene compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, budadiene or derivatives thereof, itaconic acid Polymerizable unsaturated fatty acids such as maleic acid, fumaric acid, crotonic acid, cinnamic acid, N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-octylmaleimide, N-isopropylmaleimide , N-phenylmaleimide, N-P-bromophenylmaleimide, N-O-chlorophenylmaleimide, N-cyclohexylmaleimide and other maleimide acids, maleic anhydride, itaconic anhydride, citraconic anhydride and other unsaturated carboxylic acid anhydrides , Epoxy group-containing unsaturated compounds such as allyl glycidyl ether, glycidyl methacrylate, allylamine, aminoethyl methacrylate-aminopropyl methacrylate, amino group-containing unsaturated compounds such as aminostyrene, acrylamide, N-methylacrylamide And hydroxyl group-containing unsaturated compounds such as 2-hydroxyethyl-acrylate, 3-hydroxypropyl methacrylate, 4-hydroxy-2-butene, and the like. These may be used alone or in combination of two or more.

  Of the nitrile resins, nitrile resins that can be melted at the processing temperature of the styrene resin are preferable. As such a nitrile resin, a nitrile obtained by graft copolymerization with an unsaturated nitrile, (meth) acrylic acid alkyl ester, and, if necessary, other copolymerizable monomers in the presence of a conjugated diene rubber-like polymer. Based resins.

  The conjugated diene rubbery polymer is at least 50% by weight of a conjugated diene and a monomer copolymerizable therewith, such as an unsaturated nitrile, an aromatic vinyl compound, an unsaturated carboxylic acid ester, etc. A copolymer with one kind of monomer is preferred.

  Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene and the like. From the viewpoint of good polymerizability, 1,3-butadiene and isoprene are preferable. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like, and acrylonitrile and methacrylonitrile are preferable.

  Aromatic vinyl compounds include methyl styrene, dimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, bromo styrene, dibromo styrene, tribromo styrene, chloro styrene, dichloro styrene, trichloro styrene and other styrene derivatives, and divinyl benzene. Examples thereof include functional vinyl compounds.

  As unsaturated carboxylic acid ester, acrylic acid such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, Examples include alkyl esters of methacrylic acid. Preferred are methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate.

  Specific examples of the conjugated diene rubber-like polymer include 1,3-butadiene-acrylonitrile copolymer, 1,3-butadiene-acrylonitrile-methacrylonitrile copolymer, 1,3-butadiene-acrylonitrile-styrene copolymer. Examples thereof include 1,3-butadiene-styrene copolymer. 1,3-butadiene-acrylonitrile copolymer and 1,3-butadiene-styrene copolymer are preferable. The conjugated diene rubbery polymer in 100% by weight of the nitrile resin is preferably 3 to 30% by weight.

  Monomers used for graft copolymerization in the presence of conjugated diene rubbery polymers include unsaturated nitriles, (meth) acrylic acid alkyl esters and other monomers copolymerizable with these if necessary. Is preferably used. Among them, it is more preferable to use unsaturated nitrile and (meth) acrylic acid alkyl ester.

  Examples of the unsaturated nitrile used as the graft monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and the like. Of these, acrylonitrile and methacrylonitrile are preferred. It is preferable that unsaturated nitrile is contained in an amount of 50% by weight or more in 100% by weight of the monomer used for graft copolymerization, from the viewpoint of the heat insulating property of the obtained thermoplastic resin foam. More preferably, it is 55 to 90 weight%.

  Examples of the (meth) acrylic acid alkyl ester used as the graft monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. Methyl (meth) acrylate and ethyl (meth) acrylate are preferred. In 100% by weight of the monomer used for graft copolymerization, (meth) acrylic acid alkyl ester is contained in an amount of 3% by weight to 50% by weight. This is preferable from the viewpoint of the heat insulating property of the plastic resin foam. More preferably, it is 5 to 40 weight%.

  Examples of other copolymerizable monomers include aromatic vinyl compounds, vinyl ethers, vinyl esters, and α-olefins. As the aromatic vinyl compound, styrene, methylstyrene, vinyl toluene, vinyl xylene, etc., as the vinyl ester, vinyl acetate, propion vinyl, vinyl butyrate, etc., as the vinyl ether, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, Examples of α-olefins such as methyl isopropenyl ether and ethyl isopropenyl ether include isobutene, 2-methyl-1-butene, 2-methyl-1-pentene, 2-methyl-1-hexene and 2-methyl-1-heptene. 2-methyl-1-octene, 2-ethyl-1-butene, 2-propyl-1-butene, and the like. In 100% by weight of the monomer used for graft copolymerization, the other copolymerizable monomer is preferably contained in an amount of 0% by weight to 20% by weight. If it is 20% by weight or less, it can be used according to the purpose without affecting the characteristics of the resulting nitrile resin.

  In the presence of a conjugated diene rubber-like polymer, the polymerization method of nitrile resin obtained by graft copolymerization with unsaturated nitrile, (meth) acrylic acid alkyl ester, and other copolymerizable monomers as required is emulsified. Known polymerization methods such as polymerization, solution polymerization, suspension polymerization, bulk polymerization, or a combination thereof can be applied. However, emulsion polymerization is preferably applied in consideration of ease of removal of polymerization heat, ease of post-treatment after polymerization, simplification of incidental facilities such as recovery and regeneration of organic solvents, and the like.

  In the case of the emulsion polymerization method, since the polymer product is obtained in a latex form, the polymer is coagulated and separated by a conventionally known method, for example, an aggregation method using an electrolyte or a solvent, or a freezing method. A method for obtaining a polymer by drying is raised. There is no restriction | limiting in particular in the temperature of graft polymerization, It can implement at arbitrary temperature of 0-100 degreeC. Considering the polymerization rate, conversion rate, productivity and the like, a temperature range of 30 to 70 ° C. is preferable. Moreover, it is also possible to add a plasticizer, a stabilizer, a lubricant, a dye and pigment, a filler and the like after polymerization, if necessary.

  The nitrile resin used in the present invention contains 50% by weight or more of a component derived from an unsaturated nitrile monomer in 100% by weight of the nitrile resin. Etc. are preferable because they are improved. More preferably, it is 55 to 95 weight%.

The preferred nitrile resin, in the presence of a Conjugate diene rubber-like polymer (meth) acrylonitrile, (meth) acrylate and / or (meth) acrylate, other copolymerizable optionally A nitrile resin obtained by graft copolymerization of a monomer, and a (meth) acrylonitrile- (meth) acrylic acid alkyl-butadiene copolymer containing 50% by weight or more of a component derived from (meth) acrylonitrile .

  The nitrile resin used in the present invention may be one or a combination of two or more nitrile resins having different MFR, molecular weight, molecular weight distribution, branched structure, other copolymerization component, molecular structure and the like.

  The structure of the nitrile resin used in the present invention is not particularly limited, and may be any of a random copolymer, a block copolymer, or a graft copolymer.

  The mixing ratio of the styrene resin and the nitrile resin in the present invention is such that the total amount of the thermoplastic resin composed of the styrene resin and the nitrile resin is 100% by weight, and the styrene resin is 30% by weight to 99.5% by weight. The resin content is preferably 0.5% by weight or more and 70% by weight or less. The composition of styrene resin used, MFR, molecular weight, branched structure, composition in nitrile resin, MFR, molecular weight, branched structure, depending on the balance of extrusion foamability, heat insulation, etc., but 40% by weight of styrene resin More preferred is 95% by weight or less and nitrile resin 5% by weight or more and 60% by weight or less, and particularly preferred is styrene resin 50% by weight or more and 90% by weight or less and nitrile resin 10% by weight or less 50% by weight or less. When the mixing ratio of the nitrile resin is less than 0.5% by weight, the effect of improving the heat insulation property of the obtained styrene resin foam may be insufficient. When the mixing ratio exceeds 70% by weight, excellent molding of the styrene resin is possible. There may be a problem that processability and the like are deteriorated and it becomes difficult to obtain a good thermoplastic resin foam as compared with the styrene resin alone.

  In the present invention, the styrene-based resin and the nitrile-based resin may be previously melt-mixed at a predetermined ratio using an extruder or the like before extrusion foam molding, or mixed at a predetermined ratio at the time of extrusion foam molding. Thereafter, it may be melt-mixed.

  The styrene resin and nitrile resin used in the present invention are not completely compatible only by melt kneading at the time of molding of the thermoplastic resin foam, although both are resins having a vinyl group. For example, when the glass transition temperature of the obtained thermoplastic resin foam is measured using a differential scanning calorimeter, it is observed that the glass transition temperatures derived from the styrene resin and the nitrile resin appear separately. As described above, since the styrene resin and the nitrile resin are not completely compatible, by mixing the styrene resin and the nitrile resin, the extrusion foamability and mechanical strength of the styrene resin, the gas of the nitrile resin It is thought that heat insulation can be improved while maintaining barrier properties.

  The foaming agent used in the present invention is preferably a compound having polarity from the viewpoint of foam moldability. Specifically, the foaming agent is preferably at least one selected from ethers, alcohols and water. Specific examples thereof include dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, ethers exemplified by tetrahydropyran, methanol, ethanol, Examples thereof include alcohols exemplified by propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol and t-butyl alcohol, and water. These may be used alone or in combination of two or more.

  Among the polar compounds, dimethyl ether, methanol, ethanol, and water are more preferable from the viewpoint of foam moldability, and water is particularly preferable from the viewpoint of characteristics such as foam moldability and flame retardancy.

  In the present invention, it is preferable to use various foaming agents in combination with the compound having polarity. Such a foaming agent is not particularly limited, and specific examples thereof include, for example, methane, ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, c-pentane and the like. Aliphatic hydrocarbons, methyl chloride, ethyl chloride, 1,1-difluoro-1-chloroethane (HCFC-142b), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1 -Inorganic blowing agents exemplified by halogenated hydrocarbons exemplified by difluoroethane (HFC-152a), carbon dioxide, nitrogen, air, etc., dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone Methyl i-butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl Pyrketones, ketones exemplified by ethyl n-butyl ketone, formic acid methyl ester, formic acid ethyl ester, formic acid propyl ester, formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester, carboxylic acid esters exemplified by propionic acid ethyl ester Diazo compounds exemplified by azodicarbonamide, azobisisobutyronitrile, tetrazoleamine salts such as tetrazole guanidine salt, tetrazole piperazine salt, tetrazole ammonium salt, and tetrazole metal salts such as tetrazole sodium salt and tetrazole manganese salt, For example, 5,5′-bistetrazole diguanidine salt, 5,5′-bistetrazole diammonium salt, 5,5′-bistetrazole diaminoguanidine salt, 5,5′-bistet Organic chemical foaming agents exemplified by tetrazole compounds exemplified by solpiperazine salts, N, N′-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazine, p, p′-oxybis (benzenesulfohydrazide), carbonic acid Examples thereof include carbonates, bicarbonates and the like exemplified by sodium, potassium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, aluminum carbonate, zinc carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use one or more compounds selected from the group consisting of hydrocarbons, halogenated hydrocarbons, and carbon dioxide.

  In the present invention, the foaming agent, including the polar compound, can be dissolved in a styrene resin and / or nitrile resin, or the foaming agent having a high plasticizing effect can be used to reduce the extrusion pressure, This is preferable because the foam moldability when producing a plastic resin foam is good and a low-density thermoplastic resin foam is easily obtained. Examples of the foaming agent having high solubility in styrene resin and / or nitrile resin or high plasticizing effect include the ethers such as dimethyl ether, diethyl ether, and methyl ethyl ether, methanol, ethanol, propyl alcohol, and the like. And the like, the halogenated hydrocarbons such as water, methyl chloride, and ethyl chloride, and the inorganic blowing agents such as carbon dioxide. In addition, one or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0, which will be described later, are not as high as the above compounds, but may be cited as highly soluble blowing agents. Can do.

  The foaming agent having high solubility in styrene resin and / or nitrile resin or high plasticizing effect may be a compound having high permeability to styrene resin or nitrile resin. Such a highly permeable foaming agent tends to dissipate relatively quickly from the foam. In such a case, even if the foaming agent itself is flammable, since it dissipates from the foam, properties such as flame retardancy are stabilized relatively quickly. The foaming agent having high solubility or plasticizing effect in the styrene resin and / or nitrile resin may be used alone or in combination of two or more.

  Low thermal conductivity and high heat insulation by using foaming agents that have low permeability to styrene resins and / or nitrile resins among foaming agents, including polar compounds, and low thermal conductivity as a gas A thermoplastic resin foam having properties can be obtained. In the case where a foaming agent having a high plasticizing effect and low permeability is used, both effects can be exerted on the styrene resin and / or nitrile resin. In particular, when either a styrene resin or a nitrile resin is a foaming agent having high solubility or plasticizing effect and low permeability for either one, foam molding It is possible to obtain a thermoplastic resin foam with good heat resistance, low density and low thermal conductivity and high heat insulation. By combining several foaming agents as appropriate, foam moldability, density, thermal conductivity, etc. It is possible to adjust to a desired state.

From the viewpoint of environmental compatibility, it is preferable to use one or more compounds having an ozone depletion coefficient of 0, including polar compounds. The ozone depletion coefficient means a relative value when the ozone depletion amount per unit weight of trichloromonofluoromethane (CFC-11: CCl ₃ F) is 1, and the ozone depletion coefficient is 0 This means that there is no ozone depletion action, or even if there is an ozone destruction action, the ozone depletion coefficient is 0.01 or less.

  As described above, the compound having low permeability to the styrene resin and / or nitrile resin and having an ozone depletion coefficient of 0 is selected from the group consisting of hydrocarbons and halogenated hydrocarbons. Examples of the hydrocarbon include saturated hydrocarbons having 3 to 5 carbon atoms. Specific examples include propane, n-butane, i-butane, n-pentane, i-pentane, c-pentane, neopentane, and the like. It is done. In the case of saturated hydrocarbons having 3 to 5 carbon atoms, propane, n-butane, i-butane, i-pentane, from the viewpoint of foam moldability during the production of thermoplastic resin foam and the heat insulation of the obtained foam, c-Pentane or a mixture thereof is preferred. Of the saturated hydrocarbons having 3 to 5 carbon atoms, i-butane is particularly preferable.

Examples of the halogenated hydrocarbon include hydrofluorocarbons having an ozone depletion coefficient of 0. Specifically, for example, trifluoromethane (HFC-23: CHF ₃ ), difluoromethane (HFC-32: CH ₂ F ₂ ), 1,1,1,2,2-pentafluoroethane (HFC-125: CHF) ₂ CF ₃ ), 1,1,1,2-tetrafluoroethane (HFC-134a: CH ₂ FCF ₃ ), 1,1,1-trifluoroethane (HFC-143a: CH ₃ CF ₃ ), 1,1 - difluoroethane _{(HFC-152a: CH 3 CHF} 2), 1,1,1,2,3,3,3- heptafluoropropane _{(HFC-227ea: CF 3 CHFCF} 3), 1,1,1,3,3 , 3-hexafluoropropane _{(HFC-236fa: CF 3 CH} 2 CF 3), 1,1,2,2,3- pentafluoropropane _{(HFC-245ca: CH 2 FCF} 2 CHF 2), 1 1,1,2,2-pentafluoropropane _{(HFC-245cb: CF 3 CF} 2 CH 3), 1,1,1,3,3- pentafluoropropane _{(HFC-245fa: CF 3 CH} 2 CHF 2), 1,1,1,3,3-pentafluorobutane (HFC-365mfc: CF ₃ CH ₂ CF ₂ CH ₃ ) and the like. Among these, 1,1,1,2-tetrafluoroethane (HFC-134a: CH ₂ FCF ₃ ) is used from the viewpoint of foam moldability during the production of thermoplastic resin foam and heat insulation of the obtained foam. More preferred.

Of the compounds having an ozone depletion coefficient of 0, hydrocarbons are particularly preferably used from the viewpoint of global environment such as global warming in addition to ozone layer destruction. Further, from the viewpoint of heat insulation of the obtained thermoplastic resin foam, a compound having low permeability to styrene resin and / or nitrile resin and remaining in the thermoplastic resin foam for a long time is preferably used. It is done. Examples of such compounds include saturated hydrocarbons such as i-butane, i-pentane, and c-pentane, and 1,1,1,2-tetrafluoroethane (HFC-134a: CH ₂ FCF ₃ ). And hydrofluorocarbon. Saturated hydrocarbons having 3 to 5 carbon atoms, such as n-butane, i-butane, i-pentane, c-pentane, and the like, from the viewpoint of global environmental compatibility such as protection of the ozone layer and prevention of global warming and heat insulation Most preferably, a mixture of These compounds may be used alone or in combination of two or more.

  Furthermore, foaming of thermoplastic resin foam can be achieved by appropriately combining foaming agents with low solubility in styrene resins and / or nitrile resins, or chemical foaming agents that decompose by heat and release foaming agents. It becomes easy to obtain a moldable, low-density foam. Examples of the foaming agent include the inorganic foaming agents such as nitrogen and carbon dioxide, the ketones, the carboxylic acid esters, the azo compound, the tetrazole, the organic chemical foaming agent, the carbonate, and hydrogen carbonate. Examples include salt. In particular, carbon dioxide has low thermal conductivity as a gas and high permeability to styrene resin, but low permeability to nitrile resin, and the resulting thermoplastic resin foam has a relatively low permeability. Since it can be kept for a long time, it is preferable because a foam having low thermal conductivity, good flame retardancy and excellent environmental compatibility can be obtained. Accordingly, carbon dioxide or a compound that decomposes with heat to generate carbon dioxide is preferably used.

  In the present invention, the amount of the foaming agent added or injected into the styrenic resin during the production of the styrenic resin foam is appropriately adjusted according to the setting value of the foaming ratio. The total amount of the agent is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the styrene resin. When the addition amount of the foaming agent is less than 1 part by weight, the obtained foaming ratio is low, and the characteristics such as light weight and heat insulation as the styrene resin foam may be difficult to be exhibited. On the other hand, when the amount exceeds 20 parts by weight, the amount of the foaming agent is excessive, so that defects such as voids may occur in the styrene resin foam or the flame retardancy may be lowered depending on the type of foaming agent.

  In the present invention, the mixing lower limit amount of the compound having an ozone depletion coefficient of 0 in the added foaming agent is preferably 10% by weight or more, more preferably 20% by weight or more with respect to 100% by weight of the total amount of the foaming agent. . If the mixing lower limit of the compound having an ozone depletion coefficient of 0 is less than 10% by weight, the heat insulation of the resulting thermoplastic resin foam may be inferior. When the mixing upper limit of the other blowing agent exceeds 90% by weight, if the compatibility between the other blowing agent and the styrene resin or nitrile resin is high, the plasticity is too high, and the styrene type in the extruder The kneading state of the resin or the nitrile resin and the foaming agent is not uniform, and the pressure control of the extruder tends to be difficult. On the other hand, the compatibility between the other foaming agent and the styrene resin or nitrile resin is low. In some cases, pores are generated in the thermoplastic resin foam and a good thermoplastic resin foam cannot be obtained, or the pressure control of the extruder tends to be difficult, and a flammable foaming agent is used. When it does, there exists a tendency which causes the fall of the flame retardance of a thermoplastic resin foam.

  In this invention, the pressure at the time of adding or inject | pouring a foaming agent does not restrict | limit in particular, What is necessary is just a pressure higher than internal pressures, such as an extruder.

  In the present invention, a foaming agent having a low permeability to a styrene resin, as well as a foaming agent having a high permeability to a styrene resin, Selected from the group consisting of polar compounds such as ethers and alcohols, hydrocarbons and halogenated hydrocarbons, and a compound having an ozone depletion coefficient of 0, the obtained thermoplasticity The resin foam contains the foaming agent remaining. However, in the obtained thermoplastic resin foam, the remaining content of the foaming agent is the type and amount of the compound used, the permeability of the foaming agent in the thermoplastic resin foam, the magnification or density of the thermoplastic resin foam. Depends on the required heat insulation.

  On the other hand, depending on the permeability to thermoplastic resins such as styrene-based resins and nitrile-based resins, the remaining amount decreases with time, and conversely, air enters the thermoplastic resin foam bubbles. Therefore, a thermoplastic resin foam that is produced using a compound having high permeability and consequently contains very little compound remaining in the thermoplastic resin foam is also within the scope of the present invention.

  However, when a high degree of heat insulation performance is required, such as two types of extruded polystyrene foam heat insulating plates specified in JIS A9511, and further three types, the composition of the remaining foaming agent in the obtained thermoplastic resin foam is: A foaming agent selected from the group consisting of polar compounds such as ethers and alcohols having an ozone depletion coefficient of 0, hydrocarbons and halogenated hydrocarbons, and one or more compounds and carbon dioxide remaining The lower limit of the total amount is preferably 1% by weight, more preferably 5% by weight, still more preferably 10% by weight, and particularly preferably 20% by weight. One or more compounds selected from the group consisting of polar compounds such as ethers and alcohols, hydrocarbons and halogenated hydrocarbons and having an ozone depletion coefficient of 0, in a foam of carbon dioxide When the remaining amount is less than 1% by weight, there is a tendency that it is difficult to obtain a high degree of heat insulation performance such as two or three types of extruded polystyrene foam heat insulating plates defined in JIS A9511.

  Further, when high heat insulation performance is required such as two or three types of extruded polystyrene foam heat insulating plates, the amount of the remaining foaming agent contained in the thermoplastic resin foam is generally 100% of the thermoplastic resin foam. The amount is preferably 0.1 parts by weight or more and 15 parts by weight or less, more preferably 1 part by weight or more and 10 parts by weight or less, and particularly preferably 2 parts by weight or more and 10 parts by weight or less. is there.

  Specifically, when propane is employed in the hydrocarbon, it is preferably 2 to 9 parts by weight, more preferably 3 to 9 parts by weight, n-butane, i-butane, n-pentane. , I-pentane and c-pentane are preferably used in an amount of 1 to 9 parts by weight, more preferably 2 to 8 parts by weight, and 1,1,1,2 in halogenated hydrocarbons. When tetrafluoroethane is used, the amount is preferably 1 part by weight or more and 9 parts by weight or less.

  In the present invention, the gas barrier property of the nitrile resin is selected from the group consisting of compounds having polarity such as ethers and alcohols, hydrocarbons and halogenated hydrocarbons, compared to conventional styrene resin foams, and , One or more compounds having an ozone depletion coefficient of 0, and a foaming agent such as carbon dioxide can stay in the foam for a relatively long time and can suppress the intrusion of air with high thermal conductivity, Low thermal conductivity can be maintained longer than before. However, depending on the type of foaming agent, the type of nitrile resin, the amount added, etc., the remaining amount of foaming agent decreases with time, and the gas in the foam of the thermoplastic resin foam is replaced with air.

  In the present invention, various flame retardants may be added for the purpose of improving the flame retardancy of the obtained thermoplastic resin. The flame retardant is not particularly limited, and examples thereof include halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds, metal hydroxides and hydrates.

The halogen-containing compound used in the present invention is not particularly limited. For example, tetrabromoethane, 1,2,3,4-tetrabromobutane, tetrabromocyclooctane, hexabromocyclododecane, dibromoethyldibromocyclohexane, dibromo Halogenated aliphatic compounds or derivatives thereof such as dimethylhexane and 2- (bromomethyl) -2- (hydroxymethyl) -1,3-propanediol, or halogenated alicyclic compounds or derivatives thereof, dibromoneopentyl glycol, tri Bromo neopentyl alcohol, pentaerythrityl tetrabromide, monobromodipentaerythritol, dibromodipentaerythritol, tribromodipentaerythritol, tetrabromodipentaerythritol, pentabromodipe Taerythritol, hexabromodipentaerythritol, hexabromotripentaerythritol, halogenated pentaerythritol such as polybrominated polypentaerythritol, tetrabromobisphenol A, tetrabromobisphenol S, tetrabromobisphenol A diallyl ether, tetrabromobisphenol A-bis (2-methylallyl ether), tetrabromobisphenol A-bis (3-methylallyl ether), tetrabromobisphenol A-bis (2-ethylallyl ether), tetrabromobisphenol A diglycidyl ether, tetrabromobisphenol A diglycidyl Ether and tribromophenol adduct, tetrabromobisphenol A diglycidyl ether and brominated bisphenol Halogenated bisphenols or their derivatives, such as pressurized product epoxy oligomer represented by the following general formula (1) or the compound represented by the formula (2),
General formula (1):
R- (Y) m (1)
General formula (2):
R- (O-Y) n (2)
Is mentioned.

  In the formulas (1) and (2), R is a group having an aromatic ring and / or a heterocyclic ring, for example, a benzene ring, a naphthalene ring, a group derived from bisphenols, a pyridine ring, a pyrimidine ring, for example, 1,2,3 -Triazine ring such as triazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, furan ring, thiophene ring, group represented by formula (3) or (4), etc. Y is an aliphatic group having 1 to 10 carbon atoms and a group having at least one halogen atom, preferably a halogenated alkyl group having 2 to 4 carbon atoms, a monobromoethyl group, a dibromoethyl group , Monobromopropyl group, dibromopropyl group, monobromobutyl group, dibromobutyl group and the like, and m and n each represent an integer of 1 or more.

一般式（１）または（２）で表される難燃剤の具体例としては、テトラブロモビスフェノールＡ−ビス（２，３−ジブロモプロピルエーテル）、テトラブロモビスフェノールＳビス（２，３−ジブロモプロピルエーテル）、テトラブロモビスフェノールＡ−ビス（２，３−ジブロモ−２−メチルプロピルエーテル）、トリス（２，３−ジブロモプロピル）イソシアヌレート、テトラブロモビスフェノールＡビス（２−ブロモエチルエーテル）あるいはその誘導体などがあげられる。さらには、ヘキサブロモベンゼン、ペンタブロモトルエン、エチレンビスペンタブロモジフェニル、デカブロモジフェニルエーテル、オクタブロモジフェニルエーテル、ビス（２，４，６ートリブロモフェノキシ）エタン、テトラブロモ無水フタル酸、オクタブロモトリメチルフェニルインダン、ペンタブロモベンジルアクリレート、トリブロモフェニルアリルエーテル、２，３−ジブロモプロピルペンタブロモフェニルエーテルなどのハロゲン化芳香族化合物あるいはその誘導体、テトラブロモビスフェノールＡポリカーボネートオリゴマなどのハロゲン化ビスフェノール類誘導体オリゴマー、ペンタブロモベンジルアクリレートポリマーなどのハロゲン化アクリル樹脂、エチレンビステトラブロモフタルイミド、エチレンビスジブロモノルボルナンジカルボキシイミド、２，４，６−トリス（２，４，６−トリブロモフェノキシ）１，３，５−トリアジンなどのハロゲンおよび窒素原子含有化合物、臭化アンモニウムなどの臭素化無機化合物などが挙げられる。また、後述する含リン化合物にも包含されるトリス（トリブロモネオペンチル）ホスフェート、トリス（ブロモフェニル）ホスフェートなど、さらには、スチレン系樹脂の１種である臭素化ポリスチレン樹脂も例としてあげられる。

Specific examples of the flame retardant represented by the general formula (1) or (2) include tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol S bis (2,3-dibromopropyl ether). ), Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl ether), tris (2,3-dibromopropyl) isocyanurate, tetrabromobisphenol A bis (2-bromoethyl ether) or derivatives thereof Can be given. Furthermore, hexabromobenzene, pentabromotoluene, ethylenebispentabromodiphenyl, decabromodiphenyl ether, octabromodiphenyl ether, bis (2,4,6-tribromophenoxy) ethane, tetrabromophthalic anhydride, octabromotrimethylphenylindane, Halogenated aromatic compounds such as pentabromobenzyl acrylate, tribromophenyl allyl ether, 2,3-dibromopropyl pentabromophenyl ether or derivatives thereof, halogenated bisphenol derivatives oligomers such as tetrabromobisphenol A polycarbonate oligomer, pentabromobenzyl Halogenated acrylic resins such as acrylate polymers, ethylenebistetrabromophthalimide, ethylenebisdibromono Halogen and nitrogen atom-containing compounds such as bornanedicarboximide, 2,4,6-tris (2,4,6-tribromophenoxy) 1,3,5-triazine, brominated inorganic compounds such as ammonium bromide, etc. Can be mentioned. Further, examples include tris (tribromoneopentyl) phosphate, tris (bromophenyl) phosphate and the like, which are also included in the phosphorus-containing compound described later, and brominated polystyrene resin which is one kind of styrene resin.

  Among halogen-containing compounds, halogenated aliphatic compounds such as tetrabromocyclooctane, hexabromocyclododecane, dibromoethyldibromocyclohexane or derivatives thereof, or halogenated alicyclic compounds or derivatives thereof, dibromoneopentyl glycol, tribromoneopentyl Halogenated pentaerythritol such as alcohol, halogenated bisphenols such as tetrabromobisphenol A diallyl ether, tetrabromobisphenol A-bis (2-methylallyl ether) or derivatives thereof, tetrabromobisphenol A-bis (2,3-dibromo) Propyl ether), tetrabromobisphenol S bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2,3-dibro) 2-methylpropyl ether), tris (2,3-dibromopropyl) isocyanurate, and the like are preferred from the viewpoint of flame retardancy of the thermoplastic resin foam. . A halogen-containing compound may be used independently and may be used in mixture of 2 or more types.

  The phosphorus-containing compound used in the present invention is not particularly limited and is used. For example, phosphate, phosphonate, phosphinate, phosphite, phosphoric acid, phosphonic acid, phosphinic acid or derivatives thereof, metal salts, melamine salts, ammonium salts, and phosphazenes or derivatives thereof, phosphonitriles or derivatives thereof, red phosphorus, etc. Specific examples thereof include, for example, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate, tributoxyethyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxy Aliphatic hydrocarbon monophosphates such as ethyl acid phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, Lis (isopropylphenyl) phosphate, Tris (phenylphenyl) phosphate, Trinaphthyl phosphate, Cresyl diphenyl phosphate, Xylenyl diphenyl phosphate, Diphenyl (2-ethylhexyl) phosphate, Di (isopropylphenyl) phenyl phosphate, Diphenyl-2-acryloyl Aromatic hydrocarbon monophosphates such as oxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, resorcinol diphenyl phosphate, resorcinol dixylenyl phosphate, resorcinol dicresyl phosphate, bisphenol A diphenyl phosphate, bisphenol A diki Silenyl phosphate, bisphenol A / crecresyl phosphate Hydroquinone diphenyl phosphate, hydroquinone dixylenyl phosphate, hydroquinone dicresyl phosphate, resorcinol polyphenyl phosphate, resorcinol poly (di-2,6-xylyl) phosphate bisphenol A polycresyl phosphate, hydroquinone poly (2, Examples of phosphorus-containing compounds include halogenated phosphate compounds such as condensed phosphate esters such as 6-xylyl) phosphate, tris (tribromoneopentyl) phosphate, which is also a halogen-containing compound, and tris (bromophenyl) phosphate. Melamine phosphate, melamine phosphite, melamine pyrophosphate, ammonium phosphate, ammonium pyrophosphate, ammonium phosphate amide, phosphate amide, piperazine diphosphite, piperazine phosphite, piperazine pyrophosphate, guanazole phosphite, Phosphazene, melamine polyphosphate, melan polyphosphate, melem polyphosphate, ammonium polyphosphate, ammonium polyphosphate amide, polyphosphate amide, polyphosphazene, phosphonitrile and other nitrogen-containing compounds, red phosphorus or thermosetting resin on the surface , Red phosphorus coated with metal, metal hydroxide and the like. These phosphorus-containing compounds may be used alone or in combination of two or more. Among phosphorus-containing compounds, aromatic hydrocarbon monophosphate esters such as triphenyl phosphate, condensed phosphate esters such as resorcinol diphenyl phosphate, halogen-containing phosphorus compounds such as tris (tribromoneopentyl) phosphate, and surface treatment Red phosphorus or the like is preferable from the viewpoint of flame retardancy of the thermoplastic resin foam.

  However, only a phosphorus-containing compound may be used as a flame retardant, but by combining with a halogen-containing compound, a flame retarding effect can be exhibited with a smaller amount of addition.

  The nitrogen-containing compound used in the present invention is a compound containing a nitrogen atom and is not particularly limited. Examples thereof include triazine skeleton-containing compounds, cyanuric acid or isocyanuric acid and derivatives thereof, guanidine compounds, azo compounds, and tetrazole compounds.

  Specific examples of nitrogen-containing compounds include triazine skeleton-containing compounds such as melamine, melam, melem, melon, and methylolmelamine or derivatives thereof, cyanuric acid, methyl cyanurate, diethyl cyanurate, trimethyl cyanurate, triethyl cyanurate, isocyanuric acid. Methyl isocyanurate, N, N′-diethyl isocyanurate, trismethyl isocyanurate, trisethyl isocyanurate, bis (2-carboxyethyl) isocyanurate, 1,3,5-tris (2-carboxyethyl) isocyanurate, Cyanuric acid such as tris (2,3-epoxypropyl) isocyanurate, isocyanuric acid or derivatives thereof, triazine skeleton-containing compound such as melamine, cyanuric acid or isocyanuric acid and derivatives thereof Ranaru salts such as melamine cyanurate and the like. Furthermore, the aforementioned azo compounds such as hydrazodicarbonamide, azodicarbonamide, azoisobutyronitrile, tetrazoleamine salts such as tetrazole guanidine salt, tetrazole piperazine salt, tetrazole ammonium salt, tetrazole sodium salt, tetrazole manganese salt Tetrazole compounds such as tetrazole metal salts such as 5,5-bistetrazole diguanidine salt, 5,5-bistetrazole diammonium salt, 5,5-bistetrazole diaminoguanidine salt, 5,5-bistetrazole piperazine salt For example, a compound used as a foaming agent may be used as the nitrogen-containing compound. Furthermore, the above-mentioned ethylenebistetrabromophthalimide, ethylenebisdibromonorbornanedicarboximide, 2,4,6-tris (2,4,6-tribromophenoxy) -1,3,5-triazine, tris (2 Halogen and nitrogen atom-containing compounds such as (, 3-dibromopropyl) isocyanurate may be used as nitrogen-containing compounds.

  In the nitrogen-containing compound, halogen and nitrogen atom-containing compounds such as cyanuric acid, isocyanuric acid, or derivatives thereof, melamine cyanurate, tetrazole compound, and tris (2,3-dibromopropyl) isocyanurate are used in the thermoplastic resin foam. It is preferable from the viewpoint of flame retardancy. A nitrogen-containing compound may be used independently and may mix and use 2 or more types.

  However, although only a nitrogen-containing compound may be used as a flame retardant, a flame retarding effect can be exhibited with a smaller amount of addition by combining with a halogen-containing compound.

  The boron-containing compound used in the present invention is a compound containing a boron atom and is not particularly limited. For example, boric acid, borax, metal borate, boron oxide, boron phosphate, borosilicates and the like can be mentioned.

  Specific examples of boron-containing compounds include boric acid, borax, zinc borate, barium borate, magnesium borate, calcium borate, aluminum borate, strontium borate, zirconium borate, tin borate, and other metal borate. Salts, derivatives such as hydrates of these compounds, and boron oxides such as diboron dioxide, diboron trioxide, tetraboron trioxide, and tetraboron pentoxide.

  Among the boron-containing compounds, boric acid, boron oxide and the like are preferable from the viewpoint of flame retardancy of the thermoplastic resin foam. Boron-containing compounds may be used alone or in admixture of two or more. However, only a boron-containing compound may be used as a flame retardant, but when combined with a halogen-containing compound, a flame-retardant effect can be exhibited with a smaller amount of addition.

  The sulfur-containing compound used in the present invention is a compound containing a sulfur atom and is not particularly limited. For example, sulfate compounds such as ammonium sulfate, melamine sulfate, sodium sulfate, magnesium sulfate, calcium sulfate, aluminum sulfate, and iron sulfate, sulfamic acid compounds such as sulfamic acid, ammonium sulfamate, guanidine sulfamate, benzenesulfonic acid, benzene Disulfonic acid, p-vinylbenzenesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, p-octylbenzenesulfonic acid, o-octylbenzenesulfonic acid, p-dodecylbenzenesulfonic acid, m-dodecylbenzenesulfonic acid, alkylbenzenesulfonic acid such as o-dodecylbenzenesulfonic acid, fluorobenzenesulfonic acid, chlorobenzenesulfonic acid, bromobenzenesulfonic acid, iodobenzenesulfonic acid, phenolsulfuric acid Acid, phenol disulfonic acid, sulfanilic acid (aminobenzenesulfonic acid), naphthalenesulfonic acid, 2-naphthol-1-sulfonic acid, 2-methylnaphthalene-1-sulfonic acid or lithium, sodium of these aromatic sulfonic acids, Sulfonic acids such as salts with Group 1A metals such as potassium, salts with Group 2A metals such as magnesium, calcium, barium, salts with metals such as zinc, iron, copper, etc. Compounds and the like. A sulfur-containing compound may be used independently and may mix and use 2 or more types. However, only a sulfur-containing compound may be used as a flame retardant, but when combined with a halogen-containing compound, a flame retarding effect can be exhibited with a smaller amount of addition.

  In the present invention, the thermoplastic resin composition preferably contains one or more compounds selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, and sulfur-containing compounds. Is selected from the group consisting of flammable hydrocarbons and halogenated hydrocarbons, especially by using two or more of halogen-containing compounds and phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, and sulfur-containing compounds, and , One or more compounds having an ozone depletion coefficient of 0 (specifically, saturated hydrocarbons having 3 to 5 carbon atoms such as propane, n-butane, i-butane, c-pentane) Add a large amount of halogen-containing compounds even when high heat insulation performance corresponding to 2 or 3 types of extruded polystyrene foam insulation plates is used for foaming agents. Ku, it is possible to achieve a high degree of flame retardancy prescribed in JIS A9511.

  In the present invention, the halogen-containing compound, phosphorus-containing compound, nitrogen-containing compound, boron-containing compound and sulfur-containing compound are added in combination with the respective compounds, the blowing agent species and the content thereof, styrene resin, and nitrile resin. The composition is suitably adjusted according to the density of the obtained thermoplastic resin foam, etc., but generally, it contains a halogen-containing compound, phosphorus-containing compound, and phosphorus-containing compound with respect to 100 parts by weight of the thermoplastic resin composed of a styrene resin and a nitrile resin. The total addition amount of the nitrogen compound, boron-containing compound and sulfur-containing compound is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 18 parts by weight, and 0.5 to 15 parts by weight. The following is more preferable. If the addition amount of the halogen-containing compound, phosphorus-containing compound, nitrogen-containing compound, boron-containing compound and sulfur-containing compound is less than 0.1 parts by weight, flame retardancy may not be obtained. In some cases, the moldability during the production of the plastic resin foam may be impaired.

  In the present invention, various other flame retardants other than the above, flame retardant aids, nucleating agents, plasticizers, mold release agents, antioxidants, weathering stabilizers, other stabilizers, antistatic agents, if necessary. An additive such as a colorant such as an agent and a pigment can be used. For example, silica, talc, calcium silicate, wollastonite, kaolin, mica, bentonite, smectite, montmorillonite and other silicates, zinc oxide, titanium oxide, magnesium oxide, iron oxide and other metal oxides, calcium carbonate and other inorganics Compounds, metal salts of fatty acids such as sodium stearate, magnesium stearate, barium stearate and zinc stearate, lubricants and processing aids such as liquid paraffin, olefin waxes, stearylamide compounds, phenolic antioxidants, phosphorus -Based stabilizers, nitrogen-based stabilizers, sulfur-based stabilizers, light-resistant stabilizers such as benzotriazoles and hindered amines, water-absorbing or water-swelling layered silicates such as epoxy compounds, smectites, and swellable fluoromica Organic processing products, Aqueous polymer may contain additives such as water absorbing material that can absorb water such as water anhydrous silica having silanol groups, such as manufactured by AEROSIL Japan Aerosil Corporation.

  The flame retardant aid is not particularly limited as long as it exhibits a synergistic action with a flame retardant such as a halogen-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, a boron-containing compound, or a sulfur-containing compound. Flame retardant aids, metal oxides and the like that decompose to generate radicals are preferred.

  That is, specific examples of the flame retardant aid that decomposes by heat to generate radicals include 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, and the like. It is done.

  Specific examples of the metal oxide include Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ru, Pd, Ag, Sn, W, Os, Pt, or Ce. Oxides of these. Preferably, aluminum oxide, iron oxide, titanium oxide, zinc oxide and the like are used.

  The content of the flame retardant aid in the present invention is appropriately adjusted so as to improve the flame retardancy, but is preferably 0.0001 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the styrene resin. 0.0005 to 3 parts by weight is more preferable, and 0.001 to 1 part by weight is more preferable.

  In the present invention, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis is used for more stable extrusion foaming. {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate}, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino ) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-t-butyl- 4-hydroxyphenyl) propionate, 3,5-di-tert-butyl-4-hydroxy-benzyl phosphate-diethyl ester, 1,3,5-trimethyl- , 4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate Antioxidant, triphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bisstearyl pentaerythritol diphos Phyto, bis (2,4-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) [1,1-biphenyl] -4,4 ′ -Phosphorus stabilizers such as diylbisphosphonite, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, Amine stabilizers such as killed diphenylamine, octylated diphenylamine, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, 3,3-thiobispropionic acid didecyl ester, 3,3′-thiobispropion It is preferable to add an epoxy compound such as a sulfur stabilizer such as acid dioctadecyl ester, bisphenol A-diglycidyl ether or a derivative thereof.

  In the present invention, it is preferable to add a nucleating agent such as talc or carbonate in order to form bubbles in the foam more stably.

  Furthermore, in the present invention, in order to more stably perform extrusion foam molding, fatty acid metal salts such as sodium stearate, magnesium stearate, barium stearate, zinc stearate, liquid paraffin, olefin wax, stearylamide It is preferable to add a lubricant or processing aid such as a compound.

  The cell structure of the thermoplastic resin foam in the present invention is composed of cells having a cell diameter of about 0.01 to 1 mm. However, examples of the bubble structure include a structure in which most of the bubbles are composed of bubbles having similar bubble diameters, and a structure in which the bubble diameters of the bubbles are roughly classified into two or more types. .

  The average cell diameter in the thermoplastic resin foam obtained in the present invention is preferably 0.05 mm to 1 mm, more preferably 0.06 mm to 0.6 mm, and particularly preferably 0.08 mm to 0.4 mm.

  In the cell structure in which the cell diameters are substantially uniform, in order to obtain a highly heat-insulating thermoplastic resin foam such as three types of extruded polystyrene foam, the average cell diameter is 0.08 mm or more and 0.2 mm or less. Preferably, it is 0.10 mm or more and 0.18 mm or less. However, in the cell structure in which the cell diameters are almost uniform, in order to obtain the desired thermoplastic resin foam thickness, it is necessary to increase the density of the thermoplastic resin, and the pressure during extrusion is high. Therefore, there are cases where there is a problem in lightness and economy because molding processability is deteriorated such that the discharge amount is reduced.

  In addition, the structure in which the bubble diameters of the bubbles are roughly classified into two types or three or more types is a relatively bubble having a bubble size of approximately 0.01 to 0.25 mm mainly in the thermoplastic resin foam. There is a characteristic bubble structure in which bubbles with a small diameter (small bubbles) and bubbles with a large bubble diameter (large bubbles) that are clearly larger than the small bubbles with a bubble diameter of about 0.20 to 1 mm are mixed in a sea-island shape. . While improving the heat insulation performance of the obtained thermoplastic resin foam, the thermoplastic resin foam obtained by the generation of large bubbles can be easily made with a low density and the moldability is also good. Therefore, a structure in which the bubble diameter is roughly classified into two types or three or more types is preferable. From the viewpoint of heat insulation and molding processability, the bubble size of the small bubbles and large bubbles is more preferably mainly from 0.03 mm to 0.20 mm, more preferably from 0.06 mm to 0.15 mm, and Large bubbles are 0.20 mm or more and 0.80 mm or less, and further 0.25 mm or more and 0.7 mm or less. The occupied area ratio per cross-sectional area of the foam of the small bubbles (hereinafter referred to as the small bubble area ratio) is preferably 5% to 95%, more preferably 10% to 90%, and particularly preferably 20% to 80%. It is preferably 25% or more and 70% or less. When the area ratio of small bubbles is less than 5%, the heat insulating property tends to be difficult to improve, and when it exceeds 95%, the moldability may be deteriorated such that the thickness of the thermoplastic resin foam is difficult to be obtained.

The density of the thermoplastic resin foam in the present invention is preferably 10 kg / m ³ or more and 200 kg / m ³ or less from the viewpoints of light weight and excellent heat insulation, bending strength and compressive strength. 15 kg / m ³ or more and 100 kg / m ³ or less are more preferable, and 20 kg / m ³ or less and 50 kg / m ³ or more are more preferable. If the density of the thermoplastic resin foam is less than 10 kg / m ³ , the mechanical properties such as compressive strength tend to be lowered, and if it exceeds 200 kg / m ³ , the heat insulating property tends to be lowered and it is said to be lightweight. It becomes difficult.

  The contents of the present invention are summarized as follows. That is, thermoplastic resin foams represented by conventional styrene resins have low thermal conductivity as a gas such as aliphatic hydrocarbons and halogenated hydrocarbons for the purpose of obtaining low thermal conductivity, that is, high heat insulation. Furthermore, a compound having low permeability to the styrene resin was used as the foam. However, in such a styrenic resin foam, air that is highly permeable to the styrenic resin immediately enters the foam bubbles immediately after production. Even aliphatic hydrocarbons and halogenated hydrocarbons having low permeability to the styrene resin gradually dissipate from the foam. Since the thermal conductivity of air is higher than the thermal conductivity of aliphatic hydrocarbons and halogenated hydrocarbons used as blowing agents, the thermal conductivity of the styrenic resin foam itself gradually increases, and heat insulation is achieved. There was a problem that the sex gradually decreased.

  In order to solve such a problem, in a thermoplastic resin foam, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyacrylonitrile and copolymer, polyvinylidene fluoride, in a continuous layer made of thermoplastic resin, A method of including a gas barrier resin such as polyamide has been proposed, but a thermoplastic resin foam having good extrusion foamability and low density and low thermal conductivity has not been obtained so far.

  In contrast, nitrile resins are used as gas barrier resins, and polar compounds such as ethers, alcohols, and water are used as foaming agents, resulting in good extrusion foamability, low density, and low thermal conductivity. It has been found that a thermoplastic resin foam can be obtained.

  From the above, the idea of conventional thermoplastic foams such as styrenic resin is not easy to conceive, low density, low thermal conductivity, and small increase in thermal conductivity over time, improved heat insulation A thermoplastic resin foam was obtained.

  The thermoplastic resin foam of the present invention is a thermoplastic resin composed of a styrene-based resin and a nitrile-based resin, and if necessary, a halogen-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, a boron-containing compound, a sulfur-containing compound and the like. A flame retardant is supplied to a heating and melting means such as an extruder, and a compound having polarity such as ethers, alcohols, and water is added to a thermoplastic resin as a foaming agent under a high pressure condition at any stage to form a fluid gel. It is manufactured by cooling to a temperature suitable for extrusion foaming and extruding and foaming the fluid gel through a die to a low pressure region to form a foam.

As a procedure for adding an additive such as a thermoplastic resin composed of a styrene resin and a nitrile resin, and a foaming agent and an additive such as a thermoplastic resin composed of a styrene resin and a nitrile resin and an additive, For example,
(I) A halogen-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, a boron-containing compound, a sulfur-containing compound, or other additives are mixed with a thermoplastic resin composed of a styrene resin and a nitrile resin as necessary. Then heat and melt,
(B) For styrene-based resins and / or nitrile-based resins, selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds, and other additives as necessary. One or more additives are mixed and then heated and melted, and the remaining styrene resin and / or nitrile resin and additives are added as they are or liquefied or melted as necessary, and heated and mixed.
(Ha) previously selected from the group consisting of halogen-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds and other additives as required for styrene resins and / or nitrile resins. One or more additives to be mixed, and then a heated and melted composition is prepared, and then the composition and the remaining styrenic resin and / or nitrile resin and additive, and optionally styrenic resin and / Or nitrile resin is mixed again, supplied to the extruder and melted by heating.
However, it is not limited to these.

  There are no particular restrictions on the heating temperature, melt kneading time, and melt kneading means when heat-melt kneading additives such as a thermoplastic resin composed of a styrene resin and a nitrile resin and a foaming agent.

  The heating temperature in the present invention only needs to be equal to or higher than the temperature at which the thermoplastic resin composed of the styrene resin and nitrile resin to be used is melted, but the temperature at which the molecular degradation of the resin due to the influence of the flame retardant is suppressed as much as possible, For example, about 150-260 degreeC is preferable.

  The melt kneading time in the present invention varies depending on the amount of extrusion per unit time, the melt kneading means, etc., and thus cannot be determined unconditionally, but the thermoplastic resin and the foaming agent composed of styrene resin and nitrile resin are uniformly dispersed. The time required for mixing is appropriately selected.

  Examples of the melt-kneading means in the present invention include a screw type extruder, but there is no particular limitation as long as it is used for ordinary extrusion foaming. However, in order to suppress the molecular degradation of the resin as much as possible, it is preferable to use a low shear type screw for the screw shape.

  The foam molding method in the present invention is not particularly limited. For example, the foam obtained by releasing the pressure from the slit die may be cut using a molding die and a molding roll that are placed in close contact with or in contact with the slit die. A general method for molding a plate-like foam having a large area can be used.

  There is no restriction | limiting in particular in the thickness of the styrene resin foam in this invention, According to a use, it selects suitably. For example, in the case of a heat insulating material used for a building material or the like, in order to give a preferable heat insulating property, bending strength and compressive strength, the thickness is not as thin as a sheet but as a normal plate. Is preferable, usually 10 to 150 mm is preferable, and 15 to 120 mm is more preferable.

  Next, although the thermoplastic resin foam of this invention is demonstrated still in detail based on an Example, this invention is not restrict | limited only to this Example. Note that “%” represents “% by weight” unless otherwise specified.

In the examples and comparative examples, the following compounds were used.
A: Thermoplastic resin A-1: Styrene resin: Polystyrene (G9401 manufactured by PS Japan Co., Ltd.) (MFR: 2.5 g / 10 min)
A-2: Nitrile resin: Acrylonitrile-alkyl acrylate-butadiene copolymer (acrylonitrile = 70 wt%) (Barex, Mitsui Chemicals, Inc.) (MFR: 3.0 g / 10 min)
B: Foaming agent (polar compound)
B-1: Dimethyl ether (dimethyl ether manufactured by Mitsui Chemicals, Inc.)
B-2: Ethanol (Reagent manufactured by Wako Pure Chemical Industries, Ltd.)
B-3: Water C: Foaming agent: One or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons and having an ozone depletion coefficient of 0 C-1: Isobutane (Mitsui Chemicals, Inc. ) Made isobutane)
C-2: HFC-134a (HFC-134a manufactured by Daikin Industries, Ltd.)
C-3: Cyclopentane (Cyclopentane manufactured by Taiyo Liquefied Gas Co., Ltd.)
D: Halogen-containing compound D-1: Hexabromocyclododecane (SAYTEX HP-900 manufactured by ALBEMARLE CORPORATION)
D-2: Tris (2,3-dibromopropyl) isocyanurate (TAIC-6B manufactured by Nippon Kasei Co., Ltd.)
D-3: Tetrabromobisphenol A bis (2,3-dibromopropyl ether) (fire guard 3100 manufactured by Teijin Chemicals Ltd.)
E: Phosphorus-containing compound, nitrogen-containing compound, boron-containing compound, sulfur-containing compound E-1: Tris (tribromoneopentyl) phosphate (CR-900 manufactured by Daihachi Chemical Co., Ltd.)
E-2: Isocyanuric acid (ICA-P manufactured by Shikoku Kasei Co., Ltd.)
E-3: Boron oxide (reagent manufactured by Wako Pure Chemical Industries, Ltd.)
E-4: p-Toluenesulfonic acid monohydrate (Reagent manufactured by Wako Pure Chemical Industries, Ltd.)
F: Other additives F-1: Talc (Talcan powder manufactured by Hayashi Kasei Co., Ltd.)
F-2: Barium stearate (barium stearate manufactured by Sakai Chemical Industry Co., Ltd.)
F-3: Stabilizer (IRGANOX B911 (hindered phenol antioxidant IRGANOX1076: octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate manufactured by Ciba Specialty Chemicals Co., Ltd.) Phosphorus stabilizer IRGAFOS 168: 1: 1 mixture of tris (2,4-di-t-butylphenyl) phosphite)
Evaluation and measurement methods for the obtained thermoplastic resin foam are as follows.
(1) Foam density After cutting the thermoplastic resin foam into a rectangular parallelepiped of about 200 mm x 100 mm x 25 mm, this weight is measured, and the vertical, horizontal and height dimensions are measured with a caliper, and the foam density is determined. formula:
Foam density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ )
And the unit was expressed in terms of (kg / m ³ ).
(2) Measurement was performed using a closed cell hydrometer (manufactured by Mirage) and a multi-pycnometer (manufactured by Yuasa Ionics).
(3) Thermal conductivity The thermal conductivity of the thermoplastic resin foam was measured according to JIS A9511 (2003). For measurement, HC-074 manufactured by Eihiro Seiki Co., Ltd. was used, and three rectangular parallelepiped test pieces of about 300 mm × 100 mm × 25 mm were cut out from the extruded foam, and these were arranged side by side and set in HC-074 as a shape of 300 mm × 300 mm × 25 mm. . The measurement was performed on the thermoplastic resin foam after 1 day and 100 days after removing a 10 mm portion from the surface after production.
(4) Bubble diameter Using a Sonic digital microscope BS-D8000, an image enlarged 200 times the cross section in the thickness direction of the extruded foam was taken into a personal computer. Print this image on A3 paper, draw a straight line equivalent to 1 mm in actual dimension in the thickness direction at any two locations, count the number of bubbles crossing each straight line, and the bubbles in the thickness direction at each location The diameter was calculated according to the following formula.
Bubble diameter = length of straight line 1 mm / number of bubbles crossing straight line Then, the values of the bubble diameters at two locations were arithmetically averaged to obtain the bubble diameter in the thickness direction.
(5) Partial pressure of air in foam bubbles After measurement, a 10 mm portion was removed from the surface, and then the measurement was performed for a thermoplastic resin foam that had passed 1 day and 100 days. The amount of air in the thermoplastic resin foam was analyzed and measured using a gas chromatograph (GC-14A, manufactured by Shimadzu Corporation), and the partial pressure of air in the thermoplastic resin foam bubbles was determined.
(6) Flammability The flammability of the thermoplastic resin foam was evaluated according to the following criteria using test pieces having a thickness of 10 mm, a length of 200 mm, and a width of 25 mm in accordance with JIS A9511 (2003) -Measurement Method A. The measurement was performed on the thermoplastic resin foam after 30 days after production and after cutting to the above dimensions.
(A) Burning time A: All five flame extinguishing times are within 3 seconds.
○: Of 5 flame extinguishing times, at least one exceeds 3 seconds, but the remaining 3 or more are within 3 seconds.
Δ: Out of 5 flame extinguishing times, at least 3 exceeds 3 seconds, but the remaining one or more are within 3 seconds.
X: All 5 flame extinguishing times exceed 3 seconds.
(B) Combustion distance (double-circle): It stops within the limit line with all five.
○: At least one of the five burns exceeds the limit line, but the remaining three or more burns stop within the limit line.
Δ: At least 3 out of 5 burns exceed the limit line, but the remaining one or more burns stop within the limit line.
X: Combustion exceeds the limit line with all five.
(C) Combustion status A: No burning of the foaming agent is observed.
○: Some burning of the foaming agent is observed.
Δ: Combustion of the foaming agent is observed, but no complete burning occurs.
X: Combustion of the foaming agent is observed and complete burning.

Example 1
Hexabromocyclododecane (D-1) as a flame retardant with respect to 100 parts by weight of thermoplastic resin comprising 90 parts of polystyrene (A-1) and 10 parts of acrylonitrile-alkyl acrylate-butadiene copolymer (A-2) 4 parts, 0.5 parts of talc (F-1), 0.2 parts of barium stearate (F-2) and 0.2 parts of stabilizer (F-3) were dry blended to obtain The resin mixture was supplied at a rate of about 70 kg / hr to an extruder in which the diameters of 65 mm and 90 mm were vertically connected. The resin mixture supplied to the 65 mm diameter extruder is melted or plasticized and kneaded by heating to 200 ° C., and the resin temperature is cooled to 120 ° C. with a 90 mm diameter extruder connected thereto. Extrusion was carried out into the atmosphere from a die having a rectangular cross section with a thickness direction of 2 mm and a width direction of 50 mm provided at the tip of the extruder, to obtain a rectangular parallelepiped styrene resin foam having a thickness of 55 mm and a width of 130 mm. At this time, as a foaming agent, a foaming agent composed of 29% dimethyl ether, 14% water and 57% isobutane is 7 parts with respect to 100 parts of the thermoplastic resin, in the vicinity of the tip in the extrusion direction in the 65 mm diameter extruder. The resin was press-fitted into the resin from (the end portion on the side connected to the end portion side opposite to the die of the 90 mm diameter extruder). The obtained thermoplastic resin foam has a density of 35 kg / m ³ , a closed cell ratio of 98%, and a cell structure in which cells of almost the same size are distributed almost uniformly. The average cell diameter is 0.17 mm. there were. The evaluation results are shown in Table 1.

（実施例２〜７および比較例１〜２）
ポリスチレンおよびアクリロニトリル−アクリル酸アルキル−ブタジエン共重合体の添加量、及び、発泡剤の種類および添加量を表１に示すようにした以外は、実施例１と同様にして、熱可塑性樹脂発泡体を得た（タルク、ステアリン酸バリウムおよび安定剤量は変更なし）。その評価結果を表１に示した。

(Examples 2-7 and Comparative Examples 1-2)
A thermoplastic resin foam was obtained in the same manner as in Example 1 except that the addition amount of polystyrene and acrylonitrile-alkyl acrylate-butadiene copolymer and the type and addition amount of the foaming agent were as shown in Table 1. Obtained (talc, barium stearate and stabilizer amounts unchanged). The evaluation results are shown in Table 1.

  As can be seen by comparing Examples 1 to 7 and Comparative Example 1, in the thermoplastic resin foam of the present invention, by using a nitrile resin in combination with polystyrene, the amount of infiltration of air into the foam is small, As a result, it can be seen that the change in thermal conductivity with time is small. Furthermore, as can be seen by comparing Example 2 and Comparative Example 2, the thermoplastic resin foam of the present invention has a low density and a closed cell ratio by using a polar compound such as dimethyl ether or water as a foaming agent. It can be seen that a foam having a high thermal conductivity can be obtained.

(Example 8)
Hexabromocyclododecane (D-1) as a flame retardant with respect to 100 parts by weight of thermoplastic resin comprising 70 parts of polystyrene (A-1) and 30 parts of acrylonitrile-alkyl acrylate-butadiene copolymer (A-2) 4 parts, 0.5 parts of talc (F-1), 0.2 parts of barium stearate (F-2) and 0.2 parts of stabilizer (F-3) were dry blended to obtain The resin mixture was supplied at a rate of about 70 kg / hr to an extruder in which the diameters of 65 mm and 90 mm were vertically connected. The resin mixture supplied to the 65 mm diameter extruder is melted or plasticized and kneaded by heating to 200 ° C., and the resin temperature is cooled to 120 ° C. with a 90 mm diameter extruder connected thereto. Extrusion was carried out into the atmosphere from a die having a rectangular cross section with a thickness direction of 2 mm and a width direction of 50 mm provided at the tip of the extruder, to obtain a rectangular parallelepiped styrene resin foam having a thickness of 55 mm and a width of 130 mm. At this time, as a foaming agent, a foaming agent composed of 14% water, 43% isobutane, and cyclopentane 43 is 7 parts with respect to 100 parts of the thermoplastic resin, in the vicinity of the tip in the extrusion direction in the 65 mm diameter extruder. The resin was press-fitted into the resin from (the end portion on the side connected to the end portion side opposite to the die of the 90 mm diameter extruder). The resulting thermoplastic resin foam has a density of 33 kg / m ³ , a closed cell ratio of 98%, and a cell structure in which cells of almost the same size are distributed almost uniformly, with an average cell diameter of 0.15 mm. there were. The evaluation results are shown in Table 1.

Example 9
A thermoplastic resin foam was obtained in the same manner as in Example 8 except that the type and addition amount of the foaming agent were as shown in Table 1 (the amounts of talc, barium stearate and stabilizer were not changed). The evaluation results are shown in Table 1.

  As can be seen from Examples 8 and 9, by using cyclopentane having a low thermal conductivity as a gas, a thermoplastic resin foam having a lower thermal conductivity can be obtained.

(Example 10)
Tris (2,3-dibromopropyl) as a flame retardant with respect to 100 parts by weight of thermoplastic resin comprising 70 parts of polystyrene (A-1) and 30 parts of acrylonitrile-alkyl acrylate-butadiene copolymer (A-2) A resin mixture comprising 4 parts of isocyanurate (D-2), 0.5 part of talc (F-1), 0.2 part of barium stearate (F-2) and 0.2 part of stabilizer (F-3). Dry blending was performed, and the resulting resin mixture was fed at a rate of about 70 kg / hr to an extruder in which those having a diameter of 65 mm and a diameter of 90 mm were vertically connected. The resin mixture supplied to the 65 mm diameter extruder is melted or plasticized and kneaded by heating to 200 ° C., and the resin temperature is cooled to 120 ° C. with a 90 mm diameter extruder connected thereto. Extrusion was carried out into the atmosphere from a die having a rectangular cross section with a thickness direction of 2 mm and a width direction of 50 mm provided at the tip of the extruder, to obtain a rectangular parallelepiped styrene resin foam having a thickness of 55 mm and a width of 130 mm. At this time, as a foaming agent, a foaming agent composed of 29% dimethyl ether, 14% water and 57% isobutane is 7 parts with respect to 100 parts of the thermoplastic resin, in the vicinity of the tip in the extrusion direction in the 65 mm diameter extruder. The resin was press-fitted into the resin from (the end portion on the side connected to the end portion side opposite to the die of the 90 mm diameter extruder). The resulting thermoplastic resin foam has a density of 33 kg / m ³ , a closed cell ratio of 95%, and a cell structure in which cells of almost the same size are distributed almost uniformly, with an average cell diameter of 0.18 mm. there were. The evaluation results are shown in Table 2.

（実施例１１〜１５および比較例３）
難燃剤の種類および添加量を表２に示すようにした以外は、実施例１０と同様に熱可塑性樹脂発泡体を得た（タルク、ステアリン酸バリウム、安定剤量は変更なし）。その評価結果を表２に示した。

(Examples 11 to 15 and Comparative Example 3)
A thermoplastic resin foam was obtained in the same manner as in Example 10 except that the type and addition amount of the flame retardant were as shown in Table 2 (talc, barium stearate, stabilizer amount unchanged). The evaluation results are shown in Table 2.

  As can be seen by comparing Examples 2 and 10-15 with Comparative Example 3, flame retardancy can be imparted by adding a halogen-containing compound, and Examples 2 and 10-11 are compared with Examples 12-15. As can be seen, by using a phosphorus-containing compound, a nitrogen-containing compound, a boron-containing compound, and a sulfur-containing compound in combination with the halogen-containing compound, combustion of the flammable foaming agent is suppressed, and flame retardancy is further improved. .

Claims (9)

A thermoplastic resin foam formed by extruding and foaming a thermoplastic resin composed of a styrene resin and a nitrile resin, and a thermoplastic resin composition containing a foaming agent, wherein the nitrile resin is a conjugated diene rubber (Meth) acrylonitrile- (meth) acrylic acid containing 50% by weight or more of a component derived from (meth) acrylonitrile by graft copolymerization of (meth) acrylonitrile and (meth) acrylic acid alkyl ester in the presence of a polymer A group comprising an alkyl-butadiene copolymer, the compound having one or more polarities selected from the group consisting of ethers, alcohols and water, and hydrocarbon, halogenated hydrocarbon and carbon dioxide as the foaming agent; The foam has a density of 10 kg / m ³ or more and 200 kg / m ^3. A thermoplastic resin foam characterized by: The thermoplastic resin foam according to claim 1 , wherein the thermoplastic resin comprises 30% by weight or more and 99.5% by weight or less of styrene resin and 0.5% by weight or more and 70% by weight or less of nitrile resin. . Residual blowing agent contained in the thermoplastic resin foam, ozone destroy coefficient of 0, claim, characterized in that one or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons 1 Or the thermoplastic resin foam of 2. One or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0 are selected from the group consisting of saturated hydrocarbons and hydrofluorocarbons having 3 to 5 carbon atoms The thermoplastic resin foam according to claim 3 , wherein the thermoplastic resin foam is a seed or two or more compounds. The thermoplastic resin foam 100 parts by weight, claims 1 to 4, the amount of residual blowing agent contained in the thermoplastic resin foam, characterized in that 15 parts by weight or less than 0.1 part by weight The thermoplastic resin foam according to any one of the above. This is a method for producing a thermoplastic resin foam by extruding and foaming a thermoplastic resin composition containing a foaming agent to a thermoplastic resin composed of a styrene resin and a nitrile resin that are heated and melted. Then, as the nitrile resin, (meth) acrylonitrile and (meth) acrylic acid alkyl ester are graft copolymerized in the presence of a conjugated diene rubber-like polymer, and the component derived from (meth) acrylonitrile is 50% by weight or more. A compound having at least one polarity selected from the group consisting of ethers, alcohols and water as a blowing agent , and a hydrocarbon , using the contained (meth) acrylonitrile-alkyl (meth) acrylate-butadiene copolymer you wherein Rukoto such in combination with one or more compounds selected from the group consisting of halogenated hydrocarbons and carbon dioxide Method for producing a thermoplastic resin foam. The thermoplastic resin comprising 30% by weight or more and 99.5% by weight or less of a styrene resin and 0.5% by weight or more and 70% by weight or less of a nitrile resin is used as the thermoplastic resin. A method for producing a thermoplastic resin foam. As a blowing agent other than the compound having a polar, selected from the group consisting of hydrocarbons and halogenated hydrocarbons, and claims, characterized by using one or more compounds ozone destroy coefficient of 0 6 Or the method for producing a thermoplastic resin foam according to 7 . One or more compounds selected from the group consisting of hydrocarbons and halogenated hydrocarbons having an ozone depletion coefficient of 0 are selected from the group consisting of saturated hydrocarbons and hydrofluorocarbons having 3 to 5 carbon atoms It is a seed | species or 2 or more types of compounds, The manufacturing method of the thermoplastic resin foam of Claim 8 characterized by the above-mentioned.