Expandable chlorinated vinyl chloride resin particles, expanded particles thereof, chlorinated vinyl chloride resin foamed molded article using the same, and method for producing expandable chlorinated vinyl chloride resin particles

Abstract

An object of one embodiment of the present invention is to provide expandable chlorinated vinyl chloride resin particles capable of providing a chlorinated vinyl chloride resin foamed molded product having both a high expansion ratio and excellent surface aesthetics. The expandable chlorinated vinyl chloride resin particles have a pore volume of 5.5 (ml / 100g) or less.

Description

Technical Field

[0001] The present invention relates to expandable chlorinated vinyl chloride resin particles, expandable particles thereof, chlorinated vinyl chloride resin foamed molded products using the same, and a method for producing expandable chlorinated vinyl chloride resin particles. Background Art

[0002] Resin foam has lightness, heat insulation, cushioning, etc., and has been widely used as insulation materials for housing and the like and heat preservation materials such as piping. Among resin foams, the shape of styrene resin foam moldings obtained using foamable styrene resin particles containing a foaming agent has a high degree of freedom. In addition, for foam moldings obtained from foamable styrene resin particles, styrene resin foams of various simple shapes of plates obtained by extrusion foaming methods are widely used as insulation materials that can be used in difficult-to-construct locations. Styrene resin is a resin that is easily flammable. Therefore, a flame retardant can be added to the styrene resin foam molding. As a result, the flame retardant properties of the styrene resin foam molding are ensured. However, due to fire accidents on construction sites in recent years and fire cases in high-rise apartments, thermal insulation materials for construction purposes are gradually required to have higher flame retardant properties than before.

[0003] Examples of foams having excellent flame retardancy include resin foam molded products using vinyl chloride resins or chlorinated vinyl chloride resins having excellent flame retardancy as base resins.

[0004] For example, Patent Document 1 describes a vinyl chloride resin foam sheet obtained as follows: a foamable vinyl chloride resin paste is heated to a temperature above the decomposition temperature of a thermally decomposable foaming agent, wherein the foamable vinyl chloride resin paste contains a plasticizer, a thermally decomposable foaming agent, and vinyl chloride resin particles having different polymerization degrees and particle structures in a specific ratio.

[0005] Patent Documents 2 and 3 describe foams obtained by in-mold foaming of pre-expanded chlorinated vinyl chloride resin particles obtained using a chlorinated vinyl chloride resin, a compatible solvent, and a foaming agent.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-131594

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 64-132

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2-182735 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] However, from the viewpoint of achieving both a high expansion ratio and excellent surface appearance, the above-mentioned conventional techniques are not sufficient and there is room for further improvement.

[0013] Therefore, an object of one embodiment of the present invention is to provide expandable chlorinated vinyl chloride resin particles capable of providing a chlorinated vinyl chloride resin foam-molded product having both a high expansion ratio and excellent surface appearance.

[0014] Solutions for solving problems

[0015] The inventors of the present application have repeatedly conducted in-depth studies to solve the above-mentioned problems, and as a result, have found that the porosity (pore volume) of expandable chlorinated vinyl chloride resin particles is beneficial to the foamability. Based on the above-mentioned new insights, the inventors of the present application have successfully manufactured novel expandable chlorinated vinyl chloride resin particles that can provide chlorinated vinyl chloride resin foamed molded bodies that are lightweight (high foaming ratio) and have excellent surface aesthetics, and have thus completed the present invention.

[0016] That is, the pore volume of the expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention is 5.5 (ml / 100g) or less.

[0017] In addition, a method for producing expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention includes the following steps: immediately after the chlorinated vinyl chloride resin melt containing a foaming agent that has been melt-kneaded in an extruder is extruded from a die head having a plurality of holes into pressurized water, the molten chlorinated vinyl chloride resin is cut with a rotary cutter, pelletized, and cooled and solidified, wherein the resin temperature of the chlorinated vinyl chloride resin melt containing a foaming agent at the front end of the extruder is 130 to 250°C.

[0018] In addition, a method for producing expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention includes the following steps: immediately after a molten chlorinated vinyl chloride resin containing a foaming agent that has been melt-kneaded in an extruder is extruded from a die having a plurality of holes into pressurized water, the molten chlorinated vinyl chloride resin is cut with a rotary cutter, pelletized, and cooled and solidified, wherein the pressure at the front end of the extruder is 4 to 20 MPa.

[0019] Effects of the Invention

[0020] The expandable chlorinated vinyl chloride-based resin particles according to one embodiment of the present invention can provide a chlorinated vinyl chloride-based resin foam-molded product having a high expansion ratio and excellent surface appearance. DETAILED DESCRIPTION

[0021] An embodiment of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited to the various structures described below, and various changes can be made within the scope indicated in the claims. In addition, embodiments or embodiments obtained by combining the technical means respectively disclosed in different embodiments or embodiments are also included in the protection scope of the present invention. Furthermore, by combining the means of the technologies respectively disclosed in each embodiment, new technical features can be formed. It should be noted that all academic literature and patent documents recorded in this specification are introduced as references in this specification. In addition, in this specification, unless otherwise specified, "A to B" indicating a numerical range means "above A and below B". In addition, "A and / or B" means "A, B, and A and B".

[0022] In this specification, "expandable chlorinated vinyl chloride resin particles" are sometimes simply referred to as "expandable resin particles", "chlorinated vinyl chloride resin foamed particles" are sometimes simply referred to as "foamed particles", and "chlorinated vinyl chloride resin foamed molded body" are sometimes simply referred to as "foamed molded body".

[0023] (Foamable chlorinated vinyl chloride resin particles)

[0024] The invention described in Patent Document 1 obtains a sheet-shaped foam with a very low expansion ratio of 1 to 3 times. The foam obtained according to the technology described in Patent Document 1 has an extremely low expansion ratio and is a simple shape such as a sheet. Therefore, the technology described in Patent Document 1 has a problem from the perspective of shape freedom. On the other hand, in the inventions described in Patent Documents 2 and 3, the base resin is a chlorinated vinyl chloride resin whose flame retardancy is better than that of vinyl chloride resin, and therefore has excellent flame retardancy. In addition, according to the technologies described in Patent Documents 2 and 3, a foamed molded body with shape freedom can be obtained. However, in the technologies described in Patent Documents 2 and 3, a foaming agent with a high temperature rise coefficient is used, and a large amount of organic solvents are used. Therefore, in the technologies described in Patent Documents 2 and 3, there are problems in terms of environment and cost.

[0025] Conventionally, foamed molded articles using vinyl chloride resin or chlorinated vinyl chloride resin having excellent flame retardancy as a base material have been developed. However, in view of environmental suitability and cost, it is desired to provide a foamed article which utilizes the flame retardancy of vinyl chloride resin and the like and improves lightness and shape imparting properties.

[0026] Therefore, in view of these problems, the present inventors conducted intensive research, and as a result, the present inventors obtained the following new knowledge: pores exist in expandable chlorinated vinyl chloride resin particles, and the volume of the pores (pore volume) is beneficial to the foaming property. Furthermore, the present inventors successfully exerted the effect of one embodiment of the present invention using the new expandable chlorinated vinyl chloride resin particles developed based on the new knowledge.

[0027] That is, the expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention are characterized in that the pore volume is 5.5 (ml / 100g) or less. It should be noted that the pore volume value in this specification includes the range contained by rounding off the second decimal place. According to the expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention, a chlorinated vinyl chloride resin foamed molded product having a high foaming ratio and excellent surface aesthetics can be obtained. The expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention preferably have a pore volume of 5.4 (ml / 100g) or less, more preferably a pore volume of 5.3 (ml / 100g) or less, more preferably 5.2 (ml / 100g) or less, and more preferably 5.1 (ml / 100g) or less. By making the pore volume of the expandable resin particles within the aforementioned range, it becomes difficult for the foaming agent to escape from the expandable resin particles when the expandable resin particles are foamed. As a result, a foamed molded product with a high foaming ratio can be obtained. In addition, when the foamed particles are molded, the foaming agent remains in the foamed particles, so that the secondary foaming power of the foamed particles becomes higher. As a result, a foamed molded body with excellent surface aesthetics can be obtained. The previous method for producing foamable vinyl chloride resin particles is a method of impregnating the foaming agent with a large amount of solvent. Therefore, in the previous method for producing foamable vinyl chloride resin particles, additives and the like will dissolve into the foaming agent during the impregnation of the foaming agent, so it is presumed that it becomes easy to generate pores in the obtained foamable vinyl chloride resin particles. It should be noted that the lower limit of the pore volume of the foamable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited, for example, it is 0.5 (ml / 100g) or more. In this specification, the pore volume is the pore volume measured by the mercury intrusion method, and specifically, it can be obtained by the measurement method described later.

[0028] The maximum expansion ratio (times) / volatile component amount (wt%) during foaming of the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is preferably 2.2 or more, more preferably 2.3 or more, more preferably 2.4 or more, more preferably 2.5 or more, more preferably 2.6 or more, more preferably 2.7 or more, more preferably 2.8 or more, and further preferably 2.9 or more. If the maximum expansion ratio (times) / volatile component amount (wt%) during foaming is within the aforementioned range, high foaming can be performed with a small amount of foaming agent, and the foaming efficiency is excellent. In this specification, the maximum expansion ratio is the highest ratio when foaming is evaluated in a heated air atmosphere. The method for foaming evaluation in a heated air atmosphere is described below. In this specification, the volatile component amount during foaming is the weight change rate when the expandable chlorinated vinyl chloride resin particles used in the foaming evaluation in a heated air atmosphere are heated at 150°C for 30 minutes. Specifically, it can be obtained by the measurement method described below. In addition, since the amount of volatile components in the expandable chlorinated vinyl chloride-based resin particles changes with time, it is preferred that the amount of volatile components during foaming and the foaming evaluation be measured without any interval.

[0029] (Chlorinated vinyl chloride resin)

[0030] In one embodiment of the present invention, by using a chlorinated vinyl chloride resin, expandable chlorinated vinyl chloride resin particles capable of providing a foamed molded article having both excellent flame retardancy and a high expansion ratio can be obtained.

[0031] The chlorinated vinyl chloride resin used in one embodiment of the present invention is generally manufactured as follows: using a vinyl chloride resin as a raw material, it is manufactured according to the following methods (a) and (b): method (a), in a state where the aforementioned vinyl chloride resin is dispersed in an aqueous medium, chlorine is supplied to the aqueous medium, (i) the obtained mixture is irradiated with a mercury lamp for photochlorination, or (ii) the obtained mixture is heated and chlorinated in an aqueous medium, etc.; and method (b), chlorinating the aforementioned vinyl chloride resin in an air layer, irradiating with a mercury lamp, etc.

[0032] As the chlorinated vinyl chloride resin, various vinyl chloride resins are used. Examples of the chlorinated vinyl chloride resin include (a) homopolymers of vinyl chloride, and (b) copolymers of (i) vinyl chloride and (ii) other monomers copolymerizable with vinyl chloride. Examples of other monomers copolymerizable with vinyl chloride include ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic acid esters, and vinyl ethers.

[0033] The average degree of polymerization of the vinyl chloride resin before chlorination as a raw material is not particularly limited. The lower limit of the average degree of polymerization is preferably 300 or more, more preferably 400 or more. On the other hand, the upper limit of the average degree of polymerization is preferably 3000 or less, more preferably 1500 or less. If the average degree of polymerization is within the aforementioned range, there is a tendency to obtain foamed particles with a high expansion ratio. It should be noted that the average degree of polymerization of the chlorinated vinyl chloride resin is regarded as being substantially the same as the average degree of polymerization of the vinyl chloride resin before chlorination. The average degree of polymerization of the vinyl chloride resin before chlorination is measured in accordance with JIS K6720-2.

[0034] The weight average molecular weight of the chlorinated vinyl chloride resin is not particularly limited, but is preferably in the range of 30,000 to 400,000. If the weight average molecular weight is in the above range, there is a tendency to obtain foamed particles having a high expansion ratio. The weight average molecular weight is evaluated by gel permeation chromatography as a polystyrene-equivalent molecular weight.

[0035] From the viewpoint of ensuring foamability, the chlorine content of the chlorinated vinyl chloride resin is preferably in the range of 60% by weight or more and 75% by weight or less. The chlorine content is more preferably 64% by weight or more and 70% by weight or less. There is a tendency that the higher the chlorine content, the higher the foaming ratio of the foamed particles. On the other hand, if the chlorine content is too high, the processability during extrusion tends to be significantly impaired due to the increase in melt viscosity. The chlorine content of the chlorinated vinyl chloride resin and the vinyl chloride resin is measured according to JIS K7385 B method.

[0036] As one embodiment of the present invention, among the chlorinated vinyl chloride-based resins, only one type may be used, or two or more types may be used in combination.

[0037] (foaming agent)

[0038] As the foaming agent contained in the expandable chlorinated vinyl chloride-based resin particles according to one embodiment of the present invention, a known foaming agent can be used without particular limitation, and examples thereof include the following foaming agents. As the foaming agent, for example, the following can be used: (a) (i) hydrocarbons such as n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, n-hexane, or cyclohexane; (ii) ethers such as dimethyl ether, ethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; (iii) ketones such as dimethyl ketone (acetone), methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, and ethyl n-butyl ketone; (iv) saturated alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propanol, isopropyl alcohol, butanol, isobutyl alcohol, and tert-butyl alcohol; (v) methyl formate, ethyl formate, propyl formate, butyl formate, pentyl formate, methyl propionate, and propionic acid. (vi) carboxylic acid esters such as ethyl ester, (vi) alkyl halides such as methyl chloride and ethyl chloride, (vii) hydrofluoroolefins or chlorinated hydrofluoroolefins such as trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234e), cis-1,3,3,3-tetrafluoropropene (cis-HFO-1234ze), 2,3,3,3-tetrafluoropropene (trans-HFO-1234yf), trans-1-chloro-3,3,3-trifluoropropene (trans-HCFO-1233zd), cis-1-chloro-3,3,3-trifluoropropene (cis-HCFO-1233zd), and (viii) physical blowing agents such as inorganic blowing agents such as water, carbon dioxide, and nitrogen, and (b) chemical blowing agents such as azo compounds and tetrazoles. These blowing agents may be used alone or in combination of two or more.

[0039] The expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention preferably contain a physical blowing agent as a blowing agent, and among the physical blowing agents, it is more preferable to contain at least one saturated hydrocarbon having 4 to 6 carbon atoms (4, 5 and 6 carbon atoms). Examples of the saturated hydrocarbon having 4 to 6 carbon atoms include n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, n-hexane, and cyclohexane. From the viewpoint of the solubility of the blowing agent in the resin and the retention of the blowing agent in the expandable chlorinated vinyl chloride resin particles and in the chlorinated vinyl chloride resin foamed particles, the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention preferably contain at least pentane as the saturated hydrocarbon having 4 to 6 carbon atoms.

[0040] From the viewpoint of improving the solubility of the blowing agent in the resin, the expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention preferably contain a ketone as the blowing agent. For example, by using at least one of the saturated hydrocarbons having 4 to 6 carbon atoms in combination with the ketone as the blowing agent, the solubility of the saturated hydrocarbons having 4 to 6 carbon atoms in the resin can be further improved.

[0041] As one embodiment of the present invention, the content of the foaming agent is preferably 1 to 40% by weight relative to 100% by weight of the foamable chlorinated vinyl chloride resin particles. By controlling the content of the foaming agent within the above-specified range, the following effects are achieved: foamed particles with a high expansion ratio and a foamed molded product with excellent surface aesthetics are easily obtained. A more preferred range of the content of the foaming agent is 3 to 25% by weight, and more preferably 5 to 20% by weight.

[0042] (Processing Aids)

[0043] As a preferred embodiment of the present invention, the expandable chlorinated vinyl chloride resin particles may contain a processing aid. As a processing aid, there is no particular problem as long as it is a processing aid commonly used in chlorinated vinyl chloride resins. As processing aids, for example: (a) copolymers having structural units derived from aromatic vinyl monomers and structural units derived from unsaturated nitrile monomers such as styrene-acrylonitrile copolymers (that is, copolymers having aromatic vinyl monomers and unsaturated nitrile in structural units); (b) acrylic resins; (c) impact modifiers such as methyl methacrylate-butadiene-styrene polymers; (d) chlorinated polyethylene; etc. From the aspect of easily obtaining foamed particles and foamed molded products with a high foaming ratio, the expandable chlorinated vinyl chloride resin particles preferably contain at least one selected from the group consisting of copolymers having structural units derived from aromatic vinyl monomers and structural units derived from unsaturated nitrile monomers, acrylic resins, and chlorinated polyethylene as a processing aid. From the viewpoint of improving the fluidity of the chlorinated vinyl chloride resin and improving the molding processability, the expandable chlorinated vinyl chloride resin particles more preferably contain a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer and / or an acrylic resin, and contain chlorinated polyethylene as a processing aid.

[0044] In one embodiment of the present invention, by using a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer for a chlorinated vinyl chloride resin, the following effect is excellent: foamed particles and foamed molded products with a high foaming ratio can be easily obtained during pre-foaming and foam molding under steam heating conditions.

[0045] Examples of the aromatic vinyl monomer in the copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer include styrene derivatives such as styrene, α-methylstyrene, ethylstyrene, and halogenated styrene. Examples of the unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.

[0046] The copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer may have a structural unit derived from other monomers other than the above aromatic vinyl monomer and the unsaturated nitrile monomer (that is, it may also be referred to as a structural unit derived from other monomers copolymerizable with the aromatic vinyl monomer and / or the unsaturated nitrile monomer) within the scope of not impairing the effect of one embodiment of the present invention. Examples of other monomers copolymerizable with the aromatic vinyl monomer and / or the unsaturated nitrile monomer include (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, (meth)acrylic acid, maleic anhydride, and N-substituted maleimide.

[0047] As a preferred range of the structural unit derived from the unsaturated nitrile monomer in the copolymer having the structural unit derived from the aromatic vinyl monomer and the structural unit derived from the unsaturated nitrile monomer, the copolymer having the structural unit derived from the aromatic vinyl monomer and the structural unit derived from the unsaturated nitrile monomer as a whole is taken as 100 weight %, preferably 5 to 45 weight %, more preferably 8 to 35 weight %, and further preferably 10 to 30 weight %. By making the structural unit derived from the unsaturated nitrile monomer within the above range, it is easy to obtain foamed particles and foamed molded products with a high expansion ratio.

[0048] As a preferred embodiment of a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer, a styrene-acrylonitrile copolymer can be cited. The copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer can be used in one kind only, or in combination of two or more kinds. As a preferred embodiment, a styrene-acrylonitrile copolymer is used as at least one of the copolymers having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer. For a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer, the weight average molecular weight of the copolymer is preferably higher than the weight average molecular weight of the chlorinated vinyl chloride resin used from the aspect of easily ensuring the high foaming ratio of the foamed particles obtained. It should be noted that the weight average molecular weight of the copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer is evaluated by gel permeation chromatography with a polystyrene-converted molecular weight. As a copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer, for example, Blendex869 made by Galata can be used.

[0049] The content of the copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer in the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited as long as it is within a range that does not impair the effect of one embodiment of the present invention, and is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, further preferably 5 to 35 parts by weight, and particularly preferably 8 to 30 parts by weight relative to 100 parts by weight of the chlorinated vinyl chloride resin. If the content is (a) 1 part by weight or more relative to 100 parts by weight of the chlorinated vinyl chloride resin, it is easy to obtain expandable particles and / or expandable molded articles having a high expansion ratio, and if the content is (b) 50 parts by weight or less, expandable particles and / or expandable molded articles having excellent flame retardancy can be obtained.

[0050] Specific examples of acrylic resins include: (a) polymethyl methacrylate obtained by polymerizing methyl methacrylate and polymethyl acrylate obtained by polymerizing methyl acrylate; and (b) copolymers of (i) methyl methacrylate or methyl acrylate and (ii) alkyl methacrylates such as n-butyl methacrylate having an alkyl group with 2 to 8 carbon atoms, alkyl acrylates such as ethyl acrylate having an alkyl group with 2 to 8 carbon atoms, butene, substituted styrene, acrylonitrile, and the like, which are copolymerizable with methyl methacrylate or methyl acrylate. From the perspective of easily ensuring a high expansion ratio of the obtained foamed particles, it is preferred that the acrylic resin has a weight average molecular weight higher than the weight average molecular weight of the chlorinated vinyl chloride resin used. It should be noted that the weight average molecular weight of the acrylic resin is evaluated by gel permeation chromatography as a polystyrene-converted molecular weight. As acrylic resins, for example, Kane Ace PA-40 manufactured by Kaneka can be used.

[0051] The content of the acrylic resin in the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited as long as it is within a range that does not impair the effects of one embodiment of the present invention, and is preferably 1 to 50 parts by weight, more preferably 5 to 50 parts by weight, and further preferably 8 to 30 parts by weight relative to 100 parts by weight of the chlorinated vinyl chloride resin. If the content is (a) 1 part by weight or more relative to 100 parts by weight of the chlorinated vinyl chloride resin, it is easy to obtain expandable particles and / or expandable molded articles having a high expansion ratio, and if the content is (b) 50 parts by weight or less, expandable particles and / or expandable molded articles having excellent flame retardancy can be obtained.

[0052] The content of the chlorinated polyethylene in the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited as long as it is within a range that does not impair the effects of one embodiment of the present invention, and is preferably 1 to 30 parts by weight, more preferably 2 to 25 parts by weight, and further preferably 3 to 20 parts by weight, based on 100 parts by weight of the chlorinated vinyl chloride resin. The chlorine content of the chlorinated polyethylene is measured in accordance with JIS K7385B method.

[0053] (Other additives)

[0054] The expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention may contain flame retardants, stabilizers, lubricants, nucleating agents, foaming aids, antistatic agents, radiant heat transfer inhibitors, plasticizers, solvents, and colorants such as pigments / dyes as needed, within the range that does not impair the effects of one embodiment of the present invention.

[0055] As the flame retardant, known flame retardants can be used. Examples of the flame retardant include: (a) bromine flame retardants, (b) phosphorus flame retardants, (c) boron flame retardants, (d) intumescent flame retardants such as melamine polyphosphate and ammonium polyphosphate, (e) melamine flame retardants such as melamine cyanurate, (f) hydroxides such as aluminum hydroxide and magnesium hydroxide, and (g) flame retardant aids such as antimony oxide, zinc oxide, and zinc borate.

[0056] As the stabilizer, substances that have been used in chlorinated vinyl chloride resins can be used. Examples of the stabilizer include: (a) tin stabilizers, (b) antioxidants such as phenolic compounds, phosphorus compounds, and amine compounds, (c) epoxy stabilizers, and (d) zeolites. The amount of each stabilizer in the foamable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited as long as it is within a range that does not impair the effect of one embodiment of the present invention, and is preferably 10 parts by weight or less relative to 100 parts by weight of the chlorinated vinyl chloride resin.

[0057] Examples of the lubricant include (a) waxes such as ester wax and polyethylene wax, and (b) fatty acid metal salts such as calcium stearate and zinc stearate.

[0058] Examples of the nucleating agent include inorganic compounds such as silicon dioxide, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, calcium carbonate, sodium hydrogen carbonate, zeolite, and talc.

[0059] Examples of the radiant heat transfer inhibitor include substances having the property of reflecting, scattering or absorbing light in the near-infrared or infrared region, such as graphite, graphene, carbon black, expanded graphite, titanium oxide, aluminum, and the like.

[0060] Chlorinated vinyl chloride resins may be used in combination with other resins (thermoplastic resins, thermosetting resins) within the range that does not impair the effects of one embodiment of the present invention. As the other resin, vinyl chloride resins are preferred from the perspective of flame retardancy. Examples of vinyl chloride resins include: (a) homopolymers of vinyl chloride, and (b) copolymers of (i) vinyl chloride monomers and (ii) other monomers copolymerizable with vinyl chloride. Examples of other monomers copolymerizable with vinyl chloride include ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic esters, vinyl ethers, and the like. The average degree of polymerization of the vinyl chloride resin is not particularly limited, but is preferably greater than 300 and less than 7000.

[0061] When the chlorinated vinyl chloride resin is used in combination with other resins, the amount of the other resin is not particularly limited as long as it does not impair the effects of one embodiment of the present invention, but is preferably 0 to 99 parts by weight based on 100 parts by weight of the chlorinated vinyl chloride resin.

[0062] The shape of the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is not particularly limited as long as the particles are of a shape that can be pre-foamed and foam-molded to the expandable resin particles described later. The expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention include not only general granular materials (for example, small particles with round shapes such as spherical, roughly spherical, convex lens-shaped, concave lens-shaped, spindle-shaped, etc.), but also particles with depressions. It should be noted that from the viewpoint of ensuring the filling property of the foaming particles into the molding mold and the surface aesthetics of the foamed molded body, the particle weight of the expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention is preferably 0.5 to 10 mg / particle, more preferably 1 to 8 mg / particle, and further preferably 3 to 7 mg / particle.

[0063] The expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention preferably have a true density of 1100 kg / m from the viewpoint of reducing the dissipation rate of the blowing agent from the expandable chlorinated vinyl chloride resin particles or further improving the expansion ratio of the obtained expandable particles. 3 More preferably 1150kg / m 3 More preferably 1200 kg / m 3 Above, particularly preferably 1250 kg / m 3 The true density here can be obtained by the measurement method described below.

[0064] (Method for producing expandable chlorinated vinyl chloride resin particles)

[0065] As one embodiment of the method for producing expandable chlorinated vinyl chloride resin particles according to one embodiment of the present invention (hereinafter sometimes referred to as “production method”), there can be mentioned a production method that performs the following (1) to (4):

[0066] (1) supplying a chlorinated vinyl chloride resin and various additives as required to an extruder, and melt-kneading the supplied raw materials;

[0067] (2) dissolving and dispersing the foaming agent in the molten kneaded product by using the extruder or the extruder and a subsequent dispersing device;

[0068] (3) extruding a melt-kneaded product (resin melt) of a chlorinated vinyl chloride resin composition containing a foaming agent into a cutter chamber filled with pressurized circulating water through a die head having a plurality of small holes installed in an extruder and thereafter;

[0069] (4) Immediately after extrusion from the melt-kneaded product (resin melt), the melt-kneaded product (resin melt) is cut by a rotary cutter in contact with a die head, and the melt-kneaded product is cooled and solidified by pressurized circulating water to obtain expandable chlorinated vinyl chloride resin particles.

[0070] According to the aforementioned manufacturing method, the expandable chlorinated vinyl chloride resin particles having a specified pore volume according to one embodiment of the present invention can be easily obtained. As a result, the expandable chlorinated vinyl chloride resin particles can be used to obtain a chlorinated vinyl chloride resin foamed molded body having a high foaming ratio and excellent surface aesthetics. In addition, according to the aforementioned manufacturing method, by melt-kneading the foaming agent with the chlorinated vinyl chloride resin, the viscosity of the molten resin can be reduced, and the molding processing temperature of the chlorinated vinyl chloride resin can be reduced. As a result, thermal decomposition of the chlorinated vinyl chloride resin and the vinyl chloride resin and additives used in combination as needed becomes less likely to occur.

[0071] In the aforementioned manufacture method, general extruder can be used as extruder, specifically, single screw extruder, twin screw extruder, tandem extruder etc. can be enumerated. As tandem extruder, two single screw extruders can be connected or a single screw extruder can be connected to a twin screw extruder etc. can be enumerated. In addition, extruder can also be used in combination with dispersing equipment such as a static mixer and / or a stirrer without a screw.

[0072] It should be noted that in the above-mentioned production method, it is preferred that the chlorinated vinyl chloride resin and the vinyl chloride resin used in combination as needed are fully gelled. If the gelling of the chlorinated vinyl chloride resin and the like is not fully carried out, when the chlorinated vinyl chloride resin is formed into foamable resin particles, the dissipation rate of the foaming agent from the foamable resin particles may become large, and there is a tendency that the foaming agent is difficult to contribute to foaming. As a result, it is sometimes difficult to obtain foamed particles and foamed molded products having a high expansion ratio or a high closed cell ratio.

[0073] The resin temperature during resin melt kneading may affect the thermal decomposition of chlorinated vinyl chloride resin, and vinyl chloride resin and additives used in combination as needed. Therefore, the resin temperature of the resin melt at the front end of the extruder is preferably 130 to 250°C, more preferably 140 to 240°C, and further preferably 150 to 220°C. The resin temperature of the resin melt at the front end of the extruder is a value measured by a temperature sensor installed at the front end of the extruder. In the case where two or more extruders are installed on the upstream side closer to the die head, the front end temperature of the extruder on the most downstream side is used as the resin temperature of the resin melt at the front end of the extruder in this specification. In addition, in this specification, "extruder front end" means: the front end of the downstream side of the extruder along the extrusion direction. Therefore, in the case where two or more extruders are installed on the upstream side closer to the die head, the front end temperature of the extruder installed on the most downstream side, along the extrusion direction, is used as the resin temperature of the resin melt at the front end of the extruder in this specification. If the resin temperature of the resin melt at the front end of the extruder is 130°C or higher, the resin viscosity of the resin melt decreases, and sufficient melt kneading in the extruder becomes possible. If the resin temperature of the resin melt exceeds 250°C, there is a concern of thermal decomposition of the chlorinated vinyl chloride resin and the vinyl chloride resin and additives used in combination as needed. As a result, there is a concern of inducing deterioration of the expandable chlorinated vinyl chloride resin particles and causing a decrease in foaming performance.

[0074] (Conditions of Granulation Process)

[0075] The conditions of the granulation step in the method for producing expandable chlorinated vinyl chloride-based resin particles will be described.

[0076] In the embodiment of extruding the melt-kneaded product (resin melt) from the die, the die is not particularly limited, and examples thereof include a die having a small hole preferably having a diameter of 0.3 mm to 2.0 mm, more preferably 0.4 mm to 1.5 mm.

[0077] In the method for producing the aforementioned expandable chlorinated vinyl chloride resin particles, the front end pressure of the extruder installed on the upstream side closer to the die head is preferably 4 to 20 MPa, more preferably 6 to 18 MPa, and further preferably 7 to 15 MPa. It should be noted that the front end pressure of the extruder is a value measured by a pressure sensor installed on the front end of the extruder. In the case where two or more extruders are installed on the upstream side closer to the die head, the front end pressure of the extruder on the most downstream side is taken as the front end pressure of the extruder in this specification. More specifically, in the case where two or more extruders are installed on the upstream side closer to the die head, the front end pressure of the extruder installed on the most downstream side, on the downstream side along the extrusion direction, is taken as the front end pressure of the extruder in this specification. If the front end pressure of the extruder is 4 MPa or more, it becomes easy to dissolve and disperse the foaming agent in the resin during melt kneading, and expandable chlorinated vinyl chloride resin particles can be stably obtained. On the other hand, when the extruder front end pressure is 20 MPa or less, shear heat generation during melt kneading can be suppressed, and thermal decomposition of the chlorinated vinyl chloride resin and the vinyl chloride resin and additives used in combination as required becomes less likely to occur.

[0078] In the above-mentioned method for producing expandable chlorinated vinyl chloride resin particles, when the glass transition temperature of the resin in a state without a foaming agent is set to Tg, the temperature of the molten resin (resin melt) just before extrusion from the die is preferably Tg+20°C or more, more preferably Tg+20°C to Tg+130°C, further preferably Tg+30°C to Tg+110°C, and particularly preferably Tg+40°C to Tg+90°C. It should be noted that for chlorinated vinyl chloride resins, the glass transition temperature increases with the increase in chlorine content. Therefore, it is preferred to appropriately adjust the temperature of the molten resin (resin melt) just before extrusion from the die according to the chlorine content of the chlorinated vinyl chloride resin used. If the temperature of the molten resin (resin melt) just before extrusion from the die is Tg+20°C or more, the viscosity of the extruded molten resin (resin melt) becomes low, the pores of the die are not easily clogged, and the pore opening rate of the die is not substantially reduced. Therefore, it is possible to avoid the shape of the obtained expandable chlorinated vinyl chloride resin particles being deformed or irregular. On the other hand, if the temperature of the molten resin (resin melt) just before being extruded from the die head is below Tg+130°C, the extruded molten resin (resin melt) becomes easy to solidify, and the molten resin (resin melt) becomes difficult to be wound around the rotary cutter, so the molten resin (resin melt) can be stably cut.

[0079] The aforementioned “resin without a foaming agent” means a resin including a chlorinated vinyl chloride resin, and a vinyl chloride resin, a processing aid, and an additive (except a foaming agent) used in combination as needed. The aforementioned “resin without a foaming agent” may also be referred to as a base resin described later.

[0080] In the method for producing the expandable chlorinated vinyl chloride resin particles, there is no particular limitation on the cutting device for cutting the molten resin (resin melt) extruded into the circulating pressurized cooling water. Examples of the cutting device include a device that cuts the molten resin (resin melt) into small pellets using a rotary cutter in contact with a die head, and transfers the expandable resin particles to a centrifugal dehydrator to dehydrate and collect the expandable resin particles without foaming the obtained expandable resin particles in the pressurized circulating cooling water.

[0081] The conditions for pressurized circulating cooling water should be adjusted according to the types of resins, additives, foaming agents, etc. used, and / or the content of each component. As the conditions for pressurized circulating cooling water, the following conditions are preferred: the foaming of the molten resin (resin melt) extruded from the die head is suppressed, and the molten resin (resin melt) is stably cut with a cutter. Specifically, as the temperature conditions for pressurized circulating cooling water, 40°C to 99°C is preferred, and 60°C to 90°C is more preferred.

[0082] As the pressure condition of the pressurized circulating cooling water, it is preferred to adjust the pressure so that the expansion ratio of the obtained expandable chlorinated vinyl chloride resin particles becomes 1.0 to 1.25 times. It should be noted that the expansion ratio of the expandable chlorinated vinyl chloride resin particles refers to the true density (kg / m 3 ) divided by the true density of the foamable chlorinated vinyl chloride resin particles (kg / m 3 The true density of the base resin and the expandable chlorinated vinyl chloride resin particles can be calculated as follows: a chlorinated vinyl chloride resin pellet or expandable chlorinated vinyl chloride resin pellet weighing W (kg) is allowed to settle in a measuring cylinder filled with ethanol, and the volume V (m2) is calculated from the rise in the liquid level of the measuring cylinder (immersion method). 3 Specifically, it can be obtained by the measurement method described later.

[0083] Although it depends on the type of the foaming agent used, the pressure condition of the pressurized circulating cooling water is preferably 0.6 to 2.0 MPa, more preferably 0.7 to 1.8 MPa, and even more preferably 0.8 to 1.6 MPa.

[0084] (Chlorinated vinyl chloride resin foamed particles and method for producing the same)

[0085] The expandable chlorinated vinyl chloride resin particles of one embodiment of the present invention are pre-foamed to 2 to 110 times using a heating medium such as heated air and / or steam to form chlorinated vinyl chloride resin foamed particles. Thereafter, the chlorinated vinyl chloride resin foamed particles can be used for foaming molded articles. The steam that can be used may be saturated steam or superheated steam.

[0086] The heating temperature during foaming should be appropriately adjusted according to the glass transition temperature or melting point of the resin, the content of the foaming agent, etc., and is preferably 90° C. or higher, more preferably 100° C. or higher. On the other hand, from the viewpoint of suppressing the variation of the expansion ratio between the foamed particles or preventing the shrinkage of the foamed particles, the heating temperature during foaming is preferably 150° C. or lower, more preferably 130° C. or lower.

[0087] (Chlorinated vinyl chloride resin foamed molded article and method for producing the same)

[0088] The obtained chlorinated vinyl chloride resin foamed particles are molded (e.g., in-mold molding) using a conventionally known molding machine, for example, using steam, to produce a chlorinated vinyl chloride resin foamed molded body. Depending on the shape of the mold used, a molded body of a complex shape or a block-shaped molded body can be obtained.

[0089] (Average cell diameter)

[0090] The average cell diameter of the chlorinated vinyl chloride resin foamed particles and the chlorinated vinyl chloride resin foamed molded body thereof according to one embodiment of the present invention is preferably 70 to 1000 μm, more preferably 90 to 800 μm, and further preferably 100 to 600 μm. The average cell diameter of the foamed particles and the foamed molded body is within the aforementioned range, thereby becoming a chlorinated vinyl chloride resin foamed molded body with higher thermal insulation. If the aforementioned average cell diameter is 70 μm or more, there is a tendency for the foaming ratio to be easily increased. In addition, if the aforementioned average cell diameter is 1000 μm or less, deterioration of thermal insulation performance can be avoided. The average cell diameter of the foamed particles and the foamed molded body in this specification can be obtained by the measurement method described later.

[0091] (Closed Porosity)

[0092] The closed cell ratio of the chlorinated vinyl chloride resin foamed particles and the chlorinated vinyl chloride resin foamed molded article according to one embodiment of the present invention is preferably 70% or more, more preferably 80% or more, and further preferably 90% or more. By making the closed cell ratio of the foamed particles and the foamed molded article within the aforementioned range, the following effects are achieved: the foamed particles are easily foamed twice during foamed particle molding, the moldability of the foamed particles is improved, and the surface properties of the obtained foamed molded article are improved. In addition, by making the closed cell ratio within the aforementioned range, there is a tendency to enhance the strength of the foamed molded article, such as the compressive strength.

[0093] (Application of Foam Molded Article)

[0094] The foamed molded article formed by using the foamable chlorinated vinyl chloride resin particles according to one embodiment of the present invention has a high foaming ratio and a high closed cell ratio and excellent flame retardancy. Therefore, the foamed article is suitable for various uses such as building insulation materials, ceiling materials, core materials of metal sandwich panels, food container boxes, refrigerators, cushioning materials, agricultural and fishery product boxes, bathroom insulation materials, and hot water storage tank insulation materials.

[0095] An embodiment of the present invention is not limited to the aforementioned embodiments, and various changes can be made within the scope of the claims. An embodiment obtained by appropriately combining the technical means respectively disclosed in different embodiments is also included in the protection scope of an embodiment of the present invention.

[0096] One embodiment of the present invention may also have the following configuration.

[0097] [1] Expandable chlorinated vinyl chloride resin particles having a pore volume of 5.5 (ml / 100g) or less.

[0098] [2] The expandable chlorinated vinyl chloride resin particles according to [1], wherein the maximum expansion ratio (times) / the amount of volatile components during foaming (wt%) is 2.2 or more.

[0099] [3] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [2], comprising a chlorinated vinyl chloride resin having a chlorine content of 60% by weight or more and 75% by weight or less.

[0100] [4] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [3], comprising a physical foaming agent.

[0101] [5] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [4], comprising at least one saturated hydrocarbon having 4 to 6 carbon atoms.

[0102] [6] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [5], comprising a ketone.

[0103] [7] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [6], comprising a chlorinated vinyl chloride resin having an average degree of polymerization of 300 to 3000.

[0104] [8] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [7], comprising at least one saturated hydrocarbon having 4 to 6 carbon atoms, wherein at least one of the saturated hydrocarbon having 4 to 6 carbon atoms is pentane.

[0105] [9] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [8], wherein the expandable chlorinated vinyl chloride resin particles contain 1 to 40% by weight of a blowing agent based on 100% by weight of the expandable chlorinated vinyl chloride resin particles.

[0106]

[10] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to [9], comprising a copolymer having an aromatic vinyl monomer and an unsaturated nitrile in a structural unit and / or an acrylic resin.

[0107]

[11] The expandable chlorinated vinyl chloride resin particles according to any one of [1] to

[10] , comprising chlorinated polyethylene.

[0108]

[12] A method for producing expandable chlorinated vinyl chloride resin particles, comprising the following steps: extruding a chlorinated vinyl chloride resin melt containing a foaming agent that has been melt-kneaded in an extruder from a die head having a plurality of holes into pressurized water, cutting it with a rotary cutter, pelletizing it and cooling it to solidify it, wherein the resin temperature of the chlorinated vinyl chloride resin melt containing a foaming agent at the front end of the extruder is 130 to 250°C.

[0109]

[13] A method for producing expandable chlorinated vinyl chloride resin particles, comprising the following steps: extruding a molten chlorinated vinyl chloride resin containing a foaming agent that has been melt-kneaded in an extruder from a die head having multiple holes into pressurized water, cutting it with a rotary cutter, pelletizing it and cooling it to solidify it, wherein the pressure at the front end of the extruder is 4 to 20 MPa.

[0110]

[14] A chlorinated vinyl chloride resin foamed particle, which is obtained by pre-foaming the foamable chlorinated vinyl chloride resin particles described in any one of [1] to

[11] or the foamable chlorinated vinyl chloride resin particles obtained by the method for producing foamable chlorinated vinyl chloride resin particles described in any one of

[12] or

[13] .

[0111]

[15] The chlorinated vinyl chloride resin foamed particles according to

[14] , wherein the closed cell ratio is 70% or more.

[0112]

[16] A chlorinated vinyl chloride resin foamed molded product obtained by foaming the chlorinated vinyl chloride resin foamed particles according to any one of

[14] or

[15] .

[0113]

[17] The chlorinated vinyl chloride resin foam molded product according to

[16] , which has a closed cell ratio of 70% or more.

[0114]

[18] A method for producing a chlorinated vinyl chloride resin foam molded product, comprising the step of molding the chlorinated vinyl chloride resin foam particles described in any one of

[14] or

[15] .

[0115] Example

[0116] Hereinafter, one embodiment of the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these.

[0117] In addition, the measuring method and the evaluation method in the following Examples and Comparative Examples are as follows.

[0118] <Evaluation of pore volume of expandable chlorinated vinyl chloride resin particles>

[0119] The obtained expandable chlorinated vinyl chloride resin particles were used as samples, and pore volume evaluation was carried out under the following conditions using Autopore IV9500 (manufactured by Micromeritix, Inc., USA).

[0120] Weigh 0.35g of expandable chlorinated vinyl chloride resin particles as a sample and add them to the cells described below. The cells used are those for powders, and the following are used: the sample chamber volume is 5cc, the maximum measurement volume is 0.366cc, the total stem volume is 0.392cc, the maximum mercury head pressure is 4.45psia, the cell constant is 11.117μL / pF, the external dimensions I (measured stem length) is 215mm, H (total stem length) is 230mm, and D (stem diameter) is 1.473mm. In addition, select None for the Correction method, and perform the measurement without correction. The cells to which the sample has been added are depressurized to 50μmHg, and further depressurized for 5 minutes (after maintaining the state of 50μmHg for 5 minutes, mercury is introduced for evaluation).

[0121] After the pores after decompression are filled with mercury at a pressure of 1.52 psia, the mercury is subjected to a pressure of 2 to 33,000 psia to evaluate the pore volume. It should be noted that in the specification, the amount of mercury that penetrates into the sample within the pressure range of 20 to 33,000 psia is referred to as the pore volume. The amount of mercury that penetrates into the pores of the foamable chlorinated vinyl chloride resin particles serving as the sample can be obtained from the displacement of the mercury column in the sample container. The displacement is calculated from the change in electrostatic capacitance between the mercury and the electrodes located on the tube wall of the sample container. Using Autopore IV9500 as an electrostatic capacitance detector, the displacement of the mercury column is calculated from the measured electrostatic capacitance to calculate the amount of mercury (pore volume) that penetrates into the sample.

[0122] The pressure curve during measurement is as follows. The pressure was increased to each pressure (injection pressure) described below, and the measurement was performed with the equilibrium time at each pressure being 10 seconds.

[0123] 2psia、3psia、4psia、5.5psia、7psia、8.5psia、10.5psia、13psia、16psia、20psia、23psia、25psia、30psia、40psia、50psia、60psia、75psia、90psia、115psia、140psia、175psia、220psia、270psia、330psia、420psia、520psia、640psia、700psia、800psia、990psia、1200psia、1300psia、1400psia、1500psia、1600psia、1700psia、1900psia、2050psia、2200psia、2350psia、2500psia、2650psia、2700psia、2850psia、3000psia、3250psia、3500psia、3750psia、4000psia、4250psia、4500psia、4740psia、5000psia、5300psia、5500psia、5750psia、6000psia、6250psia、6500psia、6750psia、7000psia、7500psia、8000psia、8500psia、9000psia、9300psia、9600psia、10050psia、10500psia、11000psia、11500psia、12000psia、12600psia、13100psia、13650psia、14000psia、14340psia、14600psia、15000psia、15450psia、15800psia、16200psia、16650psia、17000psia、17350psia、17700psia、18100psia、18450psia、18800psia、19200psia、19800psia、20300psia、20800psia、21200psia、21650psia、22050psia、22650psia、23200psia、23750psia、24100psia、24650psia、25050psia、25450psia、25900psia、26450psia、26950psia、27400psia、27800psia、28250psia、29000psia、29500psia、30000psia, 30450psia, 30900psia, 31300psia, 31800psia, 32350psia, 33000psia. ,

[0124] The pore radius during measurement was calculated as r = 2δcosθ / P. r: pore radius, δ: surface tension of mercury, θ: contact angle of mercury, P: indentation pressure. The contact angle of mercury was set to 130° and the surface tension was set to 485 dynes / cm, and the pores present in the sample were calculated. Both the indentation contact angle and the withdrawal contact angle were set to 130°, and the mercury density was set to 13.5335 g / ml.

[0125] <Determination of the amount of foaming agent (volatile component amount) contained in the foamable chlorinated vinyl chloride resin particles>

[0126] Measure the weight W1 (g) of the expandable chlorinated vinyl chloride resin particles. Next, heat the expandable chlorinated vinyl chloride resin particles in an oven at 150°C for 30 minutes, and then cool the heated expandable chlorinated vinyl chloride resin particles in a dryer at room temperature for 30 minutes. Then, measure the weight W2 (g) of the cooled expandable chlorinated vinyl chloride resin particles again. The weight difference (W1-W2) before and after heating is taken as the blowing agent content in the expandable chlorinated vinyl chloride resin particles. In this specification, the blowing agent content is sometimes referred to as the volatile component amount. The aforementioned volatile component amount is calculated using the following formula.

[0127] Volatile content (weight %) = (W1-W2) / W1×100

[0128] During the foaming evaluation in a heated air atmosphere described later (i.e., on the same day as the foaming evaluation), the measurement was performed under the above conditions, and the value (volatile content) calculated based on the above formula was referred to as the volatile content during foaming (wt%).

[0129] <Measurement of particle weight of expandable chlorinated vinyl chloride resin particles>

[0130] The weight of 100 randomly sampled expandable chlorinated vinyl chloride resin particles was measured using an electronic balance capable of measuring to 0.01 mg, and the particle weight was calculated using the following formula.

[0131] Particle weight (mg) = [weight of 100 expandable chlorinated vinyl chloride resin particles (mg)] / 100.

[0132] <Measurement of true density of expandable chlorinated vinyl chloride resin particles>

[0133] The expandable chlorinated vinyl chloride resin particles with a weight of W (kg) are allowed to settle in a measuring cylinder filled with ethanol, and the volume V (m2) is calculated from the rise in the liquid level of the measuring cylinder (water immersion method).3 ), calculated using the following formula.

[0134] True density of foamable chlorinated vinyl chloride resin particles (kg / m 3 )=(W / V).

[0135] <Measurement of true density of chlorinated vinyl chloride resin pellets (base resin)>

[0136] The chlorinated vinyl chloride resin is blended with auxiliary raw materials such as a processing aid, a stabilizer, and a lubricant to obtain a uniform compound. Then, the compound is melt-kneaded using an extruder to obtain chlorinated vinyl chloride resin pellets. The chlorinated vinyl chloride resin pellets weighing W (kg) are allowed to settle in a measuring cylinder filled with ethanol, and the volume V (m) is calculated from the liquid level rise of the measuring cylinder (immersion method). 3 ), calculated using the following formula.

[0137] True density of chlorinated vinyl chloride resin pellets (kg / m 3 )=(W / V)

[0138] Based on the above method, the true density of the chlorinated vinyl chloride resin pellets was measured to be 1430 kg / m 3 , and this value is used as the density of the base resin used in one embodiment of the present invention.

[0139] <Determination of expansion ratio of chlorinated vinyl chloride resin foamed particles>

[0140] The chlorinated vinyl chloride resin foamed particles with a weight of W (kg) are allowed to settle in a measuring cylinder filled with ethanol, and the volume V (m2) is calculated from the rise in the liquid level of the measuring cylinder (immersion method). 3 ) is calculated using the following formula: According to the above <Measurement of True Density of Chlorinated Vinyl Chloride Resin Pellets (Base Resin)>, the base resin density is 1430 kg / m 3 .

[0141] The expansion ratio of the chlorinated vinyl chloride-based resin foamed particles (times) = 1430 / (W / V).

[0142] <Evaluation of Foaming in Heated Air Atmosphere>

[0143] Put the expandable chlorinated vinyl chloride resin particles into an oven heated to 130°C (manufactured by AS ONE Corporation, forced convection constant temperature dryer SOFW-600). In a heated air atmosphere at a temperature of 130°C, change the heating time to foam the expandable resin particles to obtain expandable particles for each heating time. The heating time is changed at intervals of 30 seconds, such as 30 seconds, 60 seconds, 90 seconds... after the expandable resin particles are put into the oven, and heating is performed until shrinkage of the expandable particles due to excessive heating (reduction in the expandable particle ratio) is confirmed. The expandable particles for each heating time are measured based on the aforementioned <Determination of the Expandable Particle Ratio of Chlorinated Vinyl Chloride Resin Expandable Particles>. The highest expandable ratio among the obtained expandable ratios is taken as the maximum expandable ratio of the chlorinated vinyl chloride resin expandable particles. As described in the above column <Measurement of the amount of foaming agent (volatile component amount) contained in the foamable chlorinated vinyl chloride resin particles>, the volatile component amount was calculated on the same day as the foaming evaluation under the heated air atmosphere and was taken as the volatile component amount (weight %) during foaming.

[0144] <Evaluation of Foaming in a Steam Atmosphere>

[0145] Put the expandable chlorinated vinyl chloride resin particles into a pre-foaming machine (manufactured by Daikai Industry Co., Ltd.). Introduce 0.16MPa of water vapor into the pre-foaming machine, and under the condition that the temperature inside the pre-foaming machine is 90-110°C, the expandable resin particles are foamed to obtain expandable particles (chlorinated vinyl chloride resin expandable particles). Under the condition that the amount of expandable chlorinated vinyl chloride resin particles put into the pre-foaming machine is 1000g, the expandable chlorinated vinyl chloride resin particles are foamed to obtain expandable particles. The expansion ratio of the expandable particles is measured based on the aforementioned <Determination of the expansion ratio of chlorinated vinyl chloride resin expandable particles>.

[0146] <Measurement of average cell diameter of chlorinated vinyl chloride resin foamed particles>

[0147] The chlorinated vinyl chloride resin foamed particles were cut with a razor in a manner passing through the center of the chlorinated vinyl chloride resin foamed particles, and the cut surface was observed under an optical microscope. The number of cells existing in the range of 2000 μm×2000 μm square of the cut surface was measured, and the value calculated by the following formula (area average diameter) was taken as the average cell diameter. The average cell diameter of the chlorinated vinyl chloride resin foamed particles of 5 samples was measured, and the average was taken as the average cell diameter of the level.

[0148] Average cell diameter (μm) = 2 × [2000 μm × 2000 μm / (number of cells × π)] 1 / 2 .

[0149] <Determination of closed cell ratio of chlorinated vinyl chloride resin foamed particles>

[0150] The volume Vc (cm2) of an appropriate amount of expanded beads was measured using an air densimeter (Air Comparative Densimeter Model 1000 manufactured by Tokyo Science Co., Ltd.) according to the method described in ASTM D2856. 3 Then, the same foamed particles after the measurement were allowed to settle in a measuring cylinder filled with ethanol, and the volume Va (cm2) was calculated from the rise in the liquid level of the measuring cylinder (water immersion method). 3 ), and the closed cell ratio (%) was calculated according to the following formula.

[0151] Closed cell ratio (%) = (Vc / Va) × 100

[0152] <Evaluation of molding of chlorinated vinyl chloride resin foam particles>

[0153] The foamed particles obtained by the method described in the above-mentioned <Evaluation of Foaming in a Water Vapor Atmosphere> are filled into a mold for in-mold molding of 400 mm in length, 400 mm in width, and 25 mm in thickness installed in a molding machine for foamed styrene. Next, 0.12 MPa of water vapor is introduced into the mold for 30 seconds to allow the foamed particles to foam in the mold, and then water is sprayed into the mold for 20 seconds to cool the mold. The chlorinated vinyl chloride resin foamed molded body is kept in the mold until the pressure of the chlorinated vinyl chloride resin foamed molded body in the mold pressing the mold reaches 0.05 MPa (gauge pressure). Thereafter, the chlorinated vinyl chloride resin foamed molded body is taken out from the mold to obtain a rectangular chlorinated vinyl chloride resin foamed molded body.

[0154] <Measurement of the ratio of chlorinated vinyl chloride resin foamed molded products>

[0155] The longitudinal dimension X (mm), transverse dimension Y (mm), and thickness dimension Z (mm) of the foamed body are measured with a vernier caliper, and the weight W (g) of the foamed body is measured with an electronic balance. The ratio of the foamed body is calculated by the following formula. According to the above <Determination of the true density of chlorinated vinyl chloride resin pellets (base resin)>, the base resin density is 1430 kg / m 3 .

[0156] Foam molding ratio (times) = 1430 / (W / (X×Y×Z)×10 6)

[0157] <Evaluation of surface properties of chlorinated vinyl chloride resin foamed products>

[0158] The surface properties of the obtained foamed molded product were visually observed in a field of view of 300 mm×300 mm and evaluated using the following evaluation indexes.

[0159] ○: Less than 60 gaps of 3 mm or more exist between the foamed beads on the surface of the molded article.

[0160] ×: There are 60 or more gaps of 3 mm or more between the foamed beads on the surface of the molded article.

[0161] The raw materials used in Examples and Comparative Examples are shown below.

[0162] (Vinyl chloride resin)

[0163] (A-1) Chlorinated vinyl chloride resin [manufactured by Kaneka Corporation, H716S, average degree of polymerization 600, chlorine content 67.6 wt %]

[0164] (Processing Aids)

[0165] (B-1) Acrylic resin [Kane Ace PA-40 manufactured by Kaneka Corporation]

[0166] (B-2) Styrene-acrylonitrile copolymer (Galata, Blendex 869, weight average molecular weight 2.86 million, ratio of acrylonitrile-derived component in the copolymer: 20% by weight)

[0167] (foaming agent)

[0168] (C-1) n-pentane [manufactured by FUJIFILM Wako Pure Chemical Corporation]

[0169] (C-2) Acetone [manufactured by FUJIFILM Wako Pure Chemical Corporation]

[0170] (Example 1)

[0171] [Production of Expandable Chlorinated Vinyl Chloride Resin Particles]

[0172] For 100 parts by weight of chlorinated vinyl chloride resin (A-1), 10 parts by weight of acrylic resin (B-1), 5 parts by weight of mercaptobutyltin stabilizer, 3 parts by weight of lubricant (ester wax, polyethylene wax), and 5 parts by weight of chlorinated polyethylene with a chlorine content of 35% by weight are added to obtain a compound. The compound is blended to obtain a uniform compound. Thereafter, the compound is melt-kneaded in an intermeshing co-rotating twin-screw extruder to obtain pellets of the above-mentioned blending ratio. The obtained pellets are pellets of chlorinated vinyl chloride resin, and are sometimes also referred to as base resin. The obtained pellets are supplied to the twin-screw extruder at a feed rate of 40 kg / hour, and the pellets are melt-kneaded. The twin-screw extruder used has a screw diameter of Intermeshing co-rotating twin-screw extruder.

[0173] from In the middle of the co-rotating meshing twin-screw extruder, 8.8 parts by weight of n-pentane (C-1) and 3.8 parts by weight of acetone (C-2) are pressed into 100 parts by weight of the above-mentioned pellets. After that, the molten kneaded product (resin melt) is cooled to a resin temperature of 165°C through a connecting pipe, a single screw extruder, a gear pump, and a diverter valve installed at the front end of the twin-screw extruder. Then, the resin melt is extruded into pressurized circulating water at a temperature of 85°C and 1.3MPa at a discharge rate of 45kg / hour from a die head with a diameter of 1.0mm and a pad length of 3.5mm and set at 250°C installed downstream of the diverter valve. The pressure at the front end of the extruder at this time is 10MPa, and the resin temperature of the melt (that is, the resin temperature of the resin melt at the front end of the extruder) is 167°C. It should be noted that in Examples 1 to 3, the front end of the extruder refers to the front end of the single screw extruder. The extruded resin melt was cut and pelletized using a rotary cutter in contact with the die, and transferred to a centrifugal dehydrator to obtain expandable chlorinated vinyl chloride resin particles having a particle weight of 5.5 mg.

[0174] [Evaluation of pore volume of expandable vinyl chloride resin particles]

[0175] The obtained expandable chlorinated vinyl chloride resin particles were stored at 10° C. for 7 days, and the pore volume was evaluated by the method described in the above “Evaluation of pore volume of expandable chlorinated vinyl chloride resin particles” to find that it was 3.16 (ml / 100 g).

[0176] [Evaluation of Foaming of Expandable Chlorinated Vinyl Chloride Resin Particles in Heated Air Atmosphere]

[0177] After the obtained expandable chlorinated vinyl chloride resin particles were stored at 10°C for 7 days, the amount of volatile components during foaming and the foaming evaluation were carried out by the methods described in the above <Determination of the amount of foaming agent (volatile component amount) contained in the expandable chlorinated vinyl chloride resin particles> and <Foaming evaluation under heated air atmosphere>. As a result, the amount of volatile components during foaming was 9.4% by weight, and the maximum foaming ratio of the foamed particles was 26.9 times. It should be noted that the maximum foaming ratio / the amount of volatile components during foaming was 2.9. The results are shown in Table 1.

[0178] (Example 2)

[0179] In Example 1, except that 10 parts by weight of the acrylic resin (B-1) was replaced with 13 parts by weight of the styrene-acrylonitrile copolymer (B-2), expandable chlorinated vinyl chloride resin particles having a particle weight of 5.5 mg were obtained in the same manner as in Example 1. The extruder front end pressure at this time was 9 MPa, and the resin temperature of the melt was 167°C.

[0180] The pore volume of the obtained expandable chlorinated vinyl chloride resin particles was evaluated in the same manner as in Example 1.

[0181] The true density of the obtained expandable chlorinated vinyl chloride resin particles was measured by the method described in the above-mentioned <Measurement of true density of expandable chlorinated vinyl chloride resin particles> and the result was 1299 kg / m 3 .

[0182] The foaming evaluation in a heated air atmosphere was carried out in the same manner as in Example 1 with respect to the obtained expandable chlorinated vinyl chloride-based resin particles.

[0183] Table 1 shows the evaluation results.

[0184] [Production of Chlorinated Vinyl Chloride Resin Foamed Particles]

[0185] The obtained expandable chlorinated vinyl chloride resin particles were stored at 10° C. for 7 days, and then expanded particles were obtained by the method described in the above “Evaluation of Foaming in a Steam Atmosphere”. The obtained expanded particles had a magnification of 19.3 times.

[0186] The cell diameter and closed cell ratio of the obtained foamed particles were measured by the methods described in <Measurement of average cell diameter of chlorinated vinyl chloride resin foamed particles> and <Measurement of closed cell ratio of chlorinated vinyl chloride resin foamed particles>. The results showed that the average cell diameter was 580 μm and the closed cell ratio was 96%.

[0187] [Production of Chlorinated Vinyl Chloride Resin Foam Molded Article]

[0188] The obtained foamed beads were stored in an atmosphere at 30° C. for 24 hours, and then a foamed molded article was obtained by the method described in the above “Evaluation of Molding of Chlorinated Vinyl Chloride Resin”. The obtained foamed molded article had an expansion ratio of 31 times.

[0189] The surface property of the obtained foamed molded product was evaluated by the method described in the above-mentioned <Evaluation of surface property of chlorinated vinyl chloride-based resin foamed molded product>. As a result, the surface property of the molded product was 0.

[0190] (Example 3)

[0191] In Example 1, except that 10 parts by weight of acrylic resin (B-1) was changed to 13 parts by weight of styrene-acrylonitrile copolymer (B-2), 3.8 parts by weight of acetone (C-2) was changed to 2.2 parts by weight, and the die temperature was changed from 250°C to 245°C, a resin melt cooled to a resin temperature of 165°C was prepared in the same manner as in Example 1. The resin melt was extruded into pressurized circulating water at a temperature of 85°C and 1.3 MPa at an output of 44.3 kg / hour to obtain expandable chlorinated vinyl chloride resin particles having a particle weight of 4.5 mg. At this time, the pressure at the front end of the extruder was 12 MPa, and the resin temperature of the melt was 166°C.

[0192] The pore volume evaluation and the foaming evaluation in a heated air atmosphere were carried out in the same manner as in Example 1 for the obtained expandable chlorinated vinyl chloride resin particles.

[0193] Table 1 shows the evaluation results.

[0194] (Comparative Example 1)

[0195] [Production of Chlorinated Vinyl Chloride Resin Pellets]

[0196] To 100 parts by weight of chlorinated vinyl chloride resin (A-1), 10 parts by weight of acrylic resin (B-1), 5 parts by weight of mercaptobutyltin stabilizer, 3 parts by weight of lubricant (ester wax, polyethylene wax), and 5 parts by weight of chlorinated polyethylene having a chlorine content of 35% by weight were added to obtain a compound. The compound was blended to obtain a uniform compound. Thereafter, the compound was melt-kneaded in an intermeshing co-rotating twin-screw extruder to obtain pellets having the above compounding ratio.

[0197] The obtained pellets were melt-kneaded in a twin-screw extruder. Thereafter, the melt-kneaded product was extruded in the form of strands through a die head provided with a small hole of 1.7 mm in diameter installed at the front end of the extruder at a discharge rate of 8 kg / hour. After the extruded melt-kneaded product was cooled and solidified in a water tank, the solidified product was cut with a strand cutter to obtain chlorinated vinyl chloride resin pellets with a pellet weight of 6 mg.

[0198] [Production of Expandable Chlorinated Vinyl Chloride Resin Particles]

[0199] 100 parts by weight of the obtained chlorinated vinyl chloride resin particles and 170 parts by weight of n-pentane (C-1) were placed in a 100 cc pressure-resistant container and sealed. The pressure-resistant container was then heated in an oil bath at 120° C. for 24 hours and then cooled. By this operation, expandable chlorinated vinyl chloride resin particles were obtained.

[0200] [Evaluation of pore volume of expandable chlorinated vinyl chloride resin particles]

[0201] The obtained expandable chlorinated vinyl chloride resin particles were stored at 10° C. for 7 days, and the pore volume was evaluated by the method described in the above “Evaluation of pore volume of expandable chlorinated vinyl chloride resin particles” to find that it was 6.36 (ml / 100 g).

[0202] [Evaluation of Foaming of Expandable Chlorinated Vinyl Chloride Resin Particles in Heated Air Atmosphere]

[0203] After the obtained expandable chlorinated vinyl chloride resin particles were stored at 10°C for 7 days, the amount of volatile components during foaming and the foaming evaluation were carried out by the methods described in the above <Determination of the amount of foaming agent (volatile component amount) contained in the expandable chlorinated vinyl chloride resin particles> and <Foaming evaluation under heated air atmosphere>. As a result, the amount of volatile components during foaming was 12.2% by weight, and the maximum foaming ratio of the foamed particles was 22.4 times. It should be noted that the maximum foaming ratio / the amount of volatile components during foaming was 1.8. The results are shown in Table 2.

[0204] (Comparative Example 2)

[0205] In the same manner as in Comparative Example 1, expandable chlorinated vinyl chloride resin particles were obtained.

[0206] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were left to stand for 14 days under an environment of a temperature of 23° C. and a humidity of 50%.

[0207] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were stored under an environment of a temperature of 23° C. and a humidity of 50% for 14 days.

[0208] Table 2 shows the evaluation results.

[0209] (Comparative Example 3)

[0210] In Comparative Example 1, expandable chlorinated vinyl chloride resin particles having a particle weight of 5.5 mg were obtained in the same manner as in Comparative Example 1 except that 10 parts by weight of the acrylic resin (B-1) was replaced with 13 parts by weight of the styrene-acrylonitrile copolymer (B-2).

[0211] The obtained expandable chlorinated vinyl chloride resin particles were subjected to the same pore volume evaluation and foaming evaluation in a heated air atmosphere as in Comparative Example 1.

[0212] Table 2 shows the evaluation results.

[0213] (Comparative Example 4)

[0214] In the same manner as in Comparative Example 3, expandable chlorinated vinyl chloride resin particles were obtained.

[0215] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were left to stand for 14 days under an environment of a temperature of 23° C. and a humidity of 50%.

[0216] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were stored under an environment of a temperature of 23° C. and a humidity of 50% for 14 days.

[0217] Table 2 shows the evaluation results.

[0218] (Comparative Example 5)

[0219] [Production of Chlorinated Vinyl Chloride Resin Pellets]

[0220] Chlorinated vinyl chloride resin particles having a particle weight of 6 mg were obtained in the same manner as in Comparative Example 1.

[0221] [Production of Expandable Chlorinated Vinyl Chloride Resin Particles]

[0222] 100 parts by weight of the obtained chlorinated vinyl chloride resin particles, 153 parts by weight of n-pentane (C-1) and 17 parts by weight of acetone (C-2) were placed in a 100 cc pressure-resistant container and sealed. The pressure-resistant container was then heated in an oil bath at 100° C. for 12 hours and then cooled. By this operation, expandable chlorinated vinyl chloride resin particles were obtained.

[0223] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride-based resin particles were stored at 10° C. for 14 days.

[0224] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride-based resin particles were stored at 10° C. for 14 days.

[0225] Table 2 shows the evaluation results.

[0226] (Comparative Example 6)

[0227] In the same manner as in Comparative Example 5, expandable chlorinated vinyl chloride resin particles were obtained.

[0228] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were left to stand for 14 days under an environment of a temperature of 23° C. and a humidity of 50%.

[0229] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were stored under an environment of a temperature of 23° C. and a humidity of 50% for 14 days.

[0230] Table 2 shows the evaluation results.

[0231] (Comparative Example 7)

[0232] In Comparative Example 5, except that 10 parts by weight of the acrylic resin (B-1) was replaced with 13 parts by weight of the styrene-acrylonitrile copolymer (B-2), the same procedure as in Comparative Example 5 was carried out to obtain expandable chlorinated vinyl chloride resin particles having a particle weight of 5.5 mg.

[0233] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride-based resin particles were stored at 10° C. for 14 days.

[0234] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride-based resin particles were stored at 10° C. for 14 days.

[0235] Table 2 shows the evaluation results.

[0236] Expandable chlorinated vinyl chloride-based resin particles were obtained in the same manner as above except that an autoclave with a capacity of 6 L and a stirring device was used for pre-foaming and molding evaluation.

[0237] The true density of the obtained expandable chlorinated vinyl chloride resin particles was measured by the method described in the above-mentioned <Measurement of true density of expandable chlorinated vinyl chloride resin particles> and the result was 1232 kg / m 3 .

[0238] [Production of Chlorinated Vinyl Chloride Resin Foamed Particles]

[0239] The obtained expandable chlorinated vinyl chloride resin particles were stored at 10° C. for 14 days, and then expanded particles were obtained by the method described in the above “Evaluation of Foaming in a Steam Atmosphere”. The obtained expanded particles had a magnification of 20.4 times.

[0240] The average cell diameter and closed cell ratio of the obtained foamed particles were measured by the methods described in <Measurement of average cell diameter of chlorinated vinyl chloride resin foamed particles> and <Measurement of closed cell ratio of chlorinated vinyl chloride resin foamed particles>. The results showed that the average cell diameter was 540 μm and the closed cell ratio was 99%.

[0241] [Production of Chlorinated Vinyl Chloride Resin Foam Molded Article]

[0242] The obtained foamed beads were stored at 30°C for 24 hours, and then a foamed molded article was obtained by the method described in <Evaluation of molding of chlorinated vinyl chloride resin foamed beads> The obtained foamed molded article had an expansion ratio of 32 times.

[0243] The surface property of the obtained foamed molded product was evaluated by the method described in the above-mentioned <Evaluation of surface property of chlorinated vinyl chloride-based resin foamed molded product>. As a result, the surface property of the molded product was rated as ×.

[0244] (Comparative Example 8)

[0245] In the same manner as in Comparative Example 7, expandable chlorinated vinyl chloride resin particles were obtained.

[0246] The pore volume evaluation was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were left to stand for 14 days under an environment of a temperature of 23° C. and a humidity of 50%.

[0247] The foaming evaluation in the heated air atmosphere was carried out in the same manner as in Comparative Example 1 except that the obtained expandable chlorinated vinyl chloride resin particles were stored under an environment of a temperature of 23° C. and a humidity of 50% for 14 days.

[0248] Table 2 shows the evaluation results.

[0249] [Table 1]

[0250] (Table 1)

[0251]

[0252] [Table 2]

[0253]

[0254] If the above results are supplemented, Example 2 is as follows: the amount of volatile components (amount of foaming agent) is 9.7%, the amount of foamed particles is 19.3 times, and the amount of molded body is 31 times, and Comparative Example 7 is as follows: the amount of volatile components (amount of foaming agent) is 12.7%, the amount of foamed particles is 20.4 times, and the amount of molded body is 32 times. Compared with Example 2, the amount of volatile components (amount of foaming agent) during foaming in Comparative Example 7 is higher. In Comparative Example 8, which has the same amount of volatile components as Example 2, which is about 9.7%, the amount of foamed particles is 12 times, and a molded body of 30 times as large as in Example 2 cannot be obtained. That is, it can be seen that by making the pore volume less than 5.5 (ml / 100g), the foaming agent becomes less likely to detach, and the example has a high foaming ratio and excellent surface aesthetics compared to the comparative example.

[0255] Industrial Applicability

[0256] According to one embodiment of the present invention, it is possible to provide a foamable chlorinated vinyl chloride resin particle that can provide a chlorinated vinyl chloride resin foamed molded body having both a high foaming ratio and excellent surface aesthetics. In addition, the foamable resin particles, foamed particles, and foamed molded body of one embodiment of the present invention have excellent flame retardant properties. Therefore, one embodiment of the present invention is suitable for various uses such as building insulation materials, ceiling materials, core materials of metal sandwich panels, food container boxes, refrigerators, cushioning materials, agricultural and fishery product boxes, bathroom insulation materials, and hot water storage tank insulation materials.

Claims

1. A kind of expandable chlorinated vinyl chloride resin particles, wherein the pore volume is 5.5 ml / 100 g or less, and the expandable chlorinated vinyl chloride resin particles contain a physical foaming agent.

2. The expandable chlorinated vinyl chloride resin particles according to claim 1, wherein the maximum expansion ratio (times) / the amount of volatile components during foaming (wt%) is 2.2 or more. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, comprising a chlorinated vinyl chloride resin having a chlorine content of 60% by weight or more and 75% by weight or less. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, comprising at least one kind of saturated hydrocarbon having 4 to 6 carbon atoms. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, comprising ketone. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, comprising a chlorinated vinyl chloride resin having an average degree of polymerization of 300 to 3000.

7. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, comprising at least one saturated hydrocarbon having 4 to 6 carbon atoms, At least one of the saturated hydrocarbons having 4 to 6 carbon atoms is pentane.

8. The expandable chlorinated vinyl chloride resin particles according to claim 1 or 2, wherein The foaming agent is contained in 100% by weight of the foamable chlorinated vinyl chloride resin particles in an amount of 1 to 40% by weight. 9 . The expandable chlorinated vinyl chloride resin particles according to claim 1 , comprising a copolymer having an aromatic vinyl monomer and an unsaturated nitrile in a structural unit and / or an acrylic resin. 10 . The expandable chlorinated vinyl chloride resin particles according to claim 1 , comprising chlorinated polyethylene.

11. A method for producing expandable chlorinated vinyl chloride resin particles, comprising the steps of: extruding a chlorinated vinyl chloride resin melt containing a foaming agent melted and kneaded in an extruder from a die head having a plurality of holes into pressurized water, cutting the molten chlorinated vinyl chloride resin with a rotary cutter, pelletizing the molten chlorinated vinyl chloride resin with a foaming agent at the front end of the extruder at a resin temperature of 130 to 250° C., in, The temperature of the pressurized water is 40°C to 99°C, and the pressure is 0.6 to 2.0 MPa.

12. A method for producing expandable chlorinated vinyl chloride resin particles, comprising the steps of: extruding a molten chlorinated vinyl chloride resin containing a foaming agent melted and kneaded in an extruder from a die head having a plurality of holes into pressurized water, cutting the molten chlorinated vinyl chloride resin with a rotary cutter, pelletizing the molten chlorinated vinyl chloride resin, and cooling and solidifying the molten chlorinated vinyl chloride resin particles, wherein the pressure at the front end of the extruder is 4 to 20 MPa; in, The temperature of the pressurized water is 40°C to 99°C, and the pressure is 0.6 to 2.0 MPa.

13. A chlorinated vinyl chloride resin foamed particle, which is obtained by pre-foaming the foamable chlorinated vinyl chloride resin particles according to any one of claims 1 to 10 or the foamable chlorinated vinyl chloride resin particles obtained by the method for producing foamable chlorinated vinyl chloride resin particles according to any one of claims 11 or 12.

14. The chlorinated vinyl chloride resin foamed particles according to claim 13, wherein the closed cell ratio is 70% or more.

15. A chlorinated vinyl chloride resin foamed molded product obtained by foaming the chlorinated vinyl chloride resin foamed particles according to claim 13 or 14.

16. The chlorinated vinyl chloride resin foam molded product according to claim 15, which has a closed cell ratio of 70% or more.

17. A method for producing a chlorinated vinyl chloride resin foam molded product, comprising the following step: molding the chlorinated vinyl chloride resin foamed particles according to any one of claim 13 or claim 14.

Images