Foamable vinyl chloride resin particles for extrusion molding

Abstract

To provide an expandable vinyl chloride resin particle capable of providing an extrusion foam molded body having a high expansion ratio.SOLUTION: An expandable vinyl chloride resin particle for extrusion molding contains 1-20 wt.% of a physical expansion agent and has porosity of 7.5 (ml / 100 g) or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to expandable vinyl chloride resin particles for extrusion molding. [Background technology]

[0002] Vinyl chloride resins are used in a wide variety of applications due to their excellent mechanical, physical, and electrical properties, as well as moldability, etc. For example, extruded vinyl chloride resin foams are used as covering materials for electric wires and cables.

[0003] Extruded vinyl chloride resin foams can be produced by a method using a chemical foaming agent (a decomposition type foaming agent) or a method using a physical foaming agent (a volatile foaming agent).

[0004] As an example of a manufacturing method using a chemical foaming agent, Patent Document 1 discloses a technology for producing foamed molded articles with an expansion ratio of 1.3 to 3.5 times by extrusion foaming of a pellet-shaped vinyl chloride resin composition for foaming, which is a blend of a vinyl chloride resin, a methyl methacrylate copolymer, a plasticizer, and a decomposition-type foaming agent. However, manufacturing methods using chemical foaming agents have the problem that, when producing the pellet-shaped composition to be subjected to extrusion foaming, the kneading temperature must be lowered to suppress decomposition of the chemical foaming agent, resulting in insufficient kneading. When a chemical foaming agent with a high decomposition temperature is used, the extrusion temperature must be raised, which accelerates degradation of the vinyl chloride resin. As a result, it is difficult to increase the expansion ratio, and this method is limited to producing foamed molded articles with a low expansion ratio.

[0005] On the one hand, as a manufacturing method using a physical foaming agent, for example, Patent Document 2 discloses a technique for manufacturing a foamed molded article by impregnating chlorinated polyvinyl chloride-based resin composition pellets containing chlorinated polyethylene and / or chloroprene as a modifier with an organic foaming agent having a specific solubility index and then performing heat extrusion foaming. However, although this technique can obtain a foamed molded article with a high foaming ratio, it is necessary to impregnate a large amount of the physical foaming agent, and to shorten the impregnation time and suppress the scattering of the organic volatile foaming agent, it is limited to specific physical foaming agents. Further, Patent Document 3 discloses a technique for manufacturing a foamed molded article by impregnating polyvinyl chloride-based resin particles containing a homopolymer or copolymer of alkyl methacrylate having an alkyl group with 1 to 10 carbon atoms as a melt flow improver with a physical foaming agent and then performing heat extrusion foaming. However, although this technique can obtain a foamed molded article with a high foaming ratio, it is necessary to impregnate a large amount of the physical foaming agent, so the dissipation of the foaming agent is accelerated, and it is difficult to stably obtain a high-ratio extrusion foam.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide foaming vinyl chloride-based resin particles capable of providing an extrusion foamed molded article having a high foaming ratio.

Means for Solving the Problems

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have succeeded in producing novel expandable vinyl chloride resin particles that can stably give extruded foams having a high expansion ratio when the pore volume (porosity) and physical blowing agent content of the expandable vinyl chloride resin particles are within specific ranges, thereby completing the present invention.

[0009] That is, the present invention provides: [1] Expandable polyvinyl chloride resin particles for extrusion molding, containing 1 to 20% by weight of a physical foaming agent and having a porosity of 7.5 (ml / 100g) or less. [2] Expandable vinyl chloride resin particles for extrusion molding according to [1], which contain a physical foaming agent having a solubility index (SP value) of 7.4 or less. [3] Expandable vinyl chloride resin particles for extrusion molding according to [1] or [2], wherein the ratio of expansion ratio (times) to volatile content during expansion (wt%) is 2.0 or more. [4] The expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [3], wherein the physical foaming agent contains at least one saturated hydrocarbon having 4 to 6 carbon atoms. [5] The expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [4], wherein the physical foaming agent contains a ketone and / or an alkyl halide. [6] Expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [5], which contain a chlorinated vinyl chloride polymer having a chlorine content of 60% by weight or more and 75% by weight or less. [7] Expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [6], which contain a chlorinated vinyl chloride polymer having an average degree of polymerization of 300 or more and 3,000 or less. [8] The expandable vinyl chloride resin particles for extrusion molding according to any one of [4] to [7], wherein the saturated hydrocarbon having 4 to 6 carbon atoms comprises pentane. [9] Expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [8], which contain at least one selected from the group consisting of a copolymer having an aromatic vinyl monomer and an unsaturated nitrile as structural units, an acrylic resin, and a chlorinated polyethylene.

[10] Expandable vinyl chloride resin particles for extrusion molding according to any one of [1] to [9], which contain at least one plasticizer selected from the group consisting of phthalic acid plasticizers, phosphoric acid plasticizers, trimellitic acid plasticizers, epoxy plasticizers, and polyester plasticizers. Effect of the Invention

[0010] The expandable vinyl chloride resin particles for extrusion molding of the present invention can provide extruded foam molded articles having a stable high expansion ratio. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, "A to B" representing a numerical range means "A or greater and B or less." Furthermore, "A and / or B" means "A, B, and A and B."

[0012] The expandable vinyl chloride resin particles for extrusion molding according to the present invention (hereinafter sometimes referred to as "expandable vinyl chloride resin particles") are characterized by containing 1 to 20% by weight of a physical blowing agent and having a porosity of 7.5 (ml / 100g) or less. By controlling the volume of pores (porosity) present in the expandable vinyl chloride resin particles, when subjected to extrusion foam molding, the resulting extruded foam can achieve a high expansion ratio. While conventional expandable vinyl chloride resin particles require the inclusion of a large amount of physical blowing agent, the expandable vinyl chloride resin particles of the present invention can produce extruded foam molded articles with an expansion ratio equal to or higher than that of conventional ones, even with a reduced content of physical blowing agent, thereby providing cost advantages.

[0013] The expandable vinyl chloride resin particles according to one embodiment of the present invention have a porosity of 7.5 ml / 100 g or less, preferably 7.2 ml / 100 g or less, more preferably 6.9 ml / 100 g or less, even more preferably 6.7 ml / 100 g or less, and most preferably 6.5 ml / 100 g or less. Having a porosity within the above range reduces the risk of physical blowing agents escaping from the expandable vinyl chloride resin particles, and ensures sufficient gelation, which is necessary for foaming. As a result, not only is the physical blowing agent remaining in the expandable vinyl chloride resin particles improved, but extruded foams with high expansion ratios can be stably obtained even when using an extruder with poor kneading capabilities. The lower limit of the porosity of the expandable vinyl chloride resin particles according to one embodiment of the present invention is not particularly limited, but is, for example, 0.5 ml / 100 g or more. In this specification, porosity refers to the pore volume measured by mercury intrusion porosimetry, and can be determined specifically by the measurement method described below.

[0014] The foamed vinyl chloride resin particles according to an embodiment of the present invention preferably have a foaming ratio (times) / volatile content during foaming (wt%) of 2.0 or more, more preferably 2.4 or more, still more preferably 2.7 or more, and even more preferably 3.0 or more. If the maximum foaming ratio (times) / volatile content during foaming (wt%) is within the above range, high foaming is possible with a small amount of foaming agent, and it can be said that the foamed vinyl chloride resin particles have excellent foaming efficiency. In this specification, the volatile content during foaming is the weight change rate when the foamed vinyl chloride resin particles used for the extrusion foaming evaluation are heated at 150°C for 30 minutes, and specifically, it can be obtained by the measurement method described later. Note that since the volatile content in the foamed vinyl chloride resin particles changes over time, the volatile content during foaming and the extrusion foaming evaluation are measured without a time interval.

[0015] The foaming vinyl chloride resin particles of the present invention contain a vinyl chloride resin. The vinyl chloride resin is not particularly limited, and known vinyl chloride resins can be used. For example, a homopolymer of vinyl chloride, and a copolymer of a vinyl chloride monomer and another monomer copolymerizable with vinyl chloride, etc. can be mentioned. Specifically, polyvinyl chloride (vinyl chloride homopolymer); vinyl chloride-vinyl acetate copolymer, vinyl chloride-(meth)acrylic acid copolymer, vinyl chloride-(meth)methyl acrylate copolymer, vinyl chloride-(meth)ethyl acrylate copolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile terpolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-acrylonitrile copolymer, vinyl chloride-various vinyl ether copolymers, etc., vinyl chloride copolymers with other monomers copolymerizable with vinyl chloride (hereinafter sometimes referred to as "vinyl chloride copolymers"); modified (chlorinated, etc.) vinyl polymers such as post-chlorinated vinyl polymers, post-chlorinated polyvinyl chloride, post-chlorinated vinyl chloride copolymers, post-chlorinated chlorinated olefins, etc. can be mentioned. Furthermore, chlorinated polyolefins having a chemical structure similar to polyvinyl chloride, such as chlorinated polyethylene having a chlorination degree of 40% by weight or more, may be included. As the vinyl chloride resin, one or a mixture of two or more of these can be used. From the viewpoint of achieving both flame retardancy and foaming properties, it is preferable to contain at least one selected from the group consisting of polyvinyl chloride (vinyl chloride homopolymer), vinyl chloride copolymers, post-chlorinated polyvinyl chloride, and post-chlorinated vinyl chloride copolymers. In this specification, "chlorinated vinyl chloride polymer" means "post-chlorinated polyvinyl chloride (vinyl chloride homopolymer) and / or post-chlorinated vinyl chloride copolymer".

[0016] The average degree of polymerization of the vinyl chloride resin used in one embodiment of the present invention is not particularly limited, but the lower limit is preferably 300 or more, more preferably 400 or more. On the other hand, the upper limit is preferably 3000 or less, more preferably 1500 or less. If the average degree of polymerization is within the above range, a high expansion ratio tends to be obtained. The average degree of polymerization is measured in accordance with JIS K6720-2.

[0017] The weight-average molecular weight of the vinyl chloride resin used in one embodiment of the present invention is not particularly limited, but is preferably in the range of 20,000 to 400,000. A weight-average molecular weight within this range tends to provide a high expansion ratio. The weight-average molecular weight is evaluated by gel permeation chromatography in terms of polystyrene.

[0018] The chlorine content of the vinyl chloride resin used in one embodiment of the present invention is preferably in the range of 56% by weight to 75% by weight inclusive, from the viewpoint of ensuring foamability. More preferably, the lower limit is 60% by weight or more, or 63% by weight or more, and the upper limit is 70% by weight or less. A higher chlorine content tends to result in a higher expansion ratio, but if the chlorine content is too high, the melt viscosity increases, which tends to significantly impair processability. The chlorine content of the vinyl chloride resin is measured in accordance with JIS K7385 Method B.

[0019] In one embodiment of the present invention, from the viewpoint of foaming property and flame retardancy, the vinyl chloride resin preferably contains a chlorinated vinyl chloride polymer, and more preferably contains a chlorinated vinyl chloride polymer as the main component. While not particularly limited, the content of the chlorinated vinyl chloride polymer is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 70% by weight or more, and most preferably 80% by weight or more, per 100% by weight of the vinyl chloride resin. On the other hand, the upper limit is preferably 100% by weight of the chlorinated vinyl chloride polymer per 100% by weight of the vinyl chloride resin.

[0020] In one embodiment of the present invention, the average degree of polymerization of the chlorinated vinyl chloride polymer is not particularly limited, but the lower limit 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 above range, expanded beads having a high expansion ratio tend to be obtained. The average degree of polymerization of the chlorinated vinyl chloride polymer is considered to be substantially the same as the average degree of polymerization of the vinyl chloride polymer before chlorination. As described above, the average degree of polymerization of the vinyl chloride polymer before chlorination is measured in accordance with JIS K6720-2.

[0021] In one embodiment of the present invention, the vinyl chloride resin may be used alone or in combination of two or more.

[0022] The physical foaming agent contained in the foaming vinyl chloride resin particles of an embodiment of the present invention can use known physical foaming agents and is not particularly limited. For example, the following physical foaming agents can be mentioned. For example, hydrocarbons such as normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane, normal hexane, or cyclohexane; ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, tetrahydropyran; ketones such as dimethyl ketone (acetone), methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, ethyl-n-butyl ketone; saturated alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol; carboxylic acid esters such as methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, ethyl propionate; alkyl halides such as methyl chloride, ethyl chloride; 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 inorganic foaming agents such as water, carbon dioxide, and nitrogen. These foaming agents may be used alone or in combination of two or more.

[0023] As one embodiment of the present invention, the physical foaming agent has a solubility parameter (SP value) of 7.4 (cal / cm 3 ) 1 / 2It is preferable that the foaming agent contains a physical foaming agent having a density of 7.3 (cal / cm) or less. 3 ) 1 / 2 ) or less, and more preferably 7.2 or less ((cal / cm 3 ) 1 / 2 The solubility index of the physical foaming agent is 7.4 ((cal / cm 3 ) 1 / 2 ) or less, the affinity between the physical blowing agent and the vinyl chloride resin is not too high, which makes it easier to suppress the escape of the physical blowing agent and makes it easier to obtain extruded foam molded articles with a stable high expansion ratio. On the other hand, the solubility index of the physical blowing agent is 6.5 ((cal / cm 3 ) 1 / 2 ) or more, and more preferably 6.7 ((cal / cm 3 ) 1 / 2 By using a physical blowing agent with a solubility index of 6.5 or more, the solubility of the physical blowing agent in the vinyl chloride resin is increased, making it easier for the physical blowing agent to be stably retained in the vinyl chloride resin.

[0024] In one embodiment of the present invention, from the viewpoint of foaming properties, the physical foaming agent preferably contains at least one saturated hydrocarbon having 4 to 6 carbon atoms (4, 5, and 6 carbon atoms). Examples of saturated hydrocarbons having 4 to 6 carbon atoms include normal butane, isobutane, normal pentane, isopentane, neopentane, cyclopentane, normal hexane, and cyclohexane. In one embodiment of the present invention, from the viewpoint of the solubility of the foaming agent in the resin and the retention of the foamable vinyl chloride resin particles, the saturated hydrocarbon having 4 to 6 carbon atoms preferably contains at least pentane.

[0025] In one embodiment of the present invention, the physical blowing agent preferably contains at least one selected from the group consisting of ketones, alkyl halides, ethers, hydrofluoroolefins, and hydrochlorofluoroolefins, from the viewpoint of improving the solubility of the physical blowing agent in vinyl chloride resins, and more preferably contains a ketone and / or an alkyl halide. For example, by using at least one saturated hydrocarbon having 4 to 6 carbon atoms in combination with a ketone and / or an alkyl halide as the physical blowing agent, the solubility of the saturated hydrocarbon having 4 to 6 carbon atoms in vinyl chloride resins can be further improved. Preferred ketones include methyl ethyl ketone, acetone, and diethyl ketone, and preferred alkyl halides include methylene chloride and ethyl chloride.

[0026] When a physical blowing agent containing a saturated hydrocarbon having 4 to 6 carbon atoms and at least one selected from the group consisting of ketones, alkyl halides, ethers, hydrofluoroolefins, and hydrochlorofluoroolefins is used in combination, the proportion of the hydrocarbon in 100% by weight of the physical blowing agent is preferably 20% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, and particularly preferably 50% by weight or more, from the viewpoint of foaming ability and retention of the blowing agent. Alternatively, the proportion of the hydrocarbon in the physical blowing agent is preferably 97% by weight or less, more preferably 95% by weight or less, and even more preferably 92% by weight or less, from the viewpoint of solubility of the physical blowing agent in vinyl chloride resins.

[0027] In one embodiment of the present invention, the content of the physical foaming agent is 1 to 20% by weight relative to 100% by weight of the expandable vinyl chloride resin particles. From the viewpoints of plasticization during extrusion and expansion ratio, the content of the physical foaming agent is preferably in the range of 2 to 17% by weight, more preferably 3 to 15% by weight.

[0028] In one embodiment of the present invention, as long as the composition contains a physical foaming agent, it may further contain a chemical foaming agent. As the chemical foaming agent, known decomposition type foaming agents can be used, such as sodium bicarbonate, citrate, azo compounds, and tetrazole.

[0029] In one embodiment of the present invention, the expandable vinyl chloride resin particles may contain a processing aid. Any processing aid commonly used for vinyl chloride resins may be used. Examples of processing aids include copolymers having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer, such as styrene-acrylonitrile copolymers (i.e., copolymers having aromatic vinyl monomers and unsaturated nitrile structural units), acrylic resins, impact modifiers such as methyl methacrylate-butadiene-styrene polymers, and chlorinated polyethylene. From the viewpoint of improving expandability, the expandable vinyl chloride resin particles preferably contain, as the processing aid, at least one selected from the group consisting of copolymers having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer, acrylic resins, and chlorinated polyethylene. From the viewpoint of improving the fluidity and molding processability of the vinyl chloride resin, it is more preferable to include a copolymer having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer and / or an acrylic resin, and chlorinated polyethylene.

[0030] In one embodiment of the present invention, by using a copolymer having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer as a vinyl chloride resin, it is easy to obtain extruded foam molded articles with a high expansion ratio.

[0031] In the copolymer having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer, examples of the aromatic vinyl monomer include styrene, α-methylstyrene, ethylstyrene, halogenated styrene, and other styrene derivatives. Examples of the unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.

[0032] Within the range that does not impair the effects of one embodiment of the present invention, a copolymer having structural units derived from an aromatic vinyl monomer and structural units derived from an unsaturated nitrile monomer may have structural units derived from other monomers other than the above aromatic vinyl monomer and unsaturated nitrile monomer (that is, it can also be said to be structural units derived from other monomers copolymerizable with the aromatic vinyl monomer and / or unsaturated nitrile monomer). Examples of other monomers copolymerizable with the aromatic vinyl monomer and / or unsaturated nitrile monomer include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, N-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid, maleic anhydride, N-substituted maleimide, and the like.

[0033] As a preferable range of the structural units derived from the unsaturated nitrile monomer in the copolymer having structural units derived from the aromatic vinyl monomer and structural units derived from the unsaturated nitrile monomer, taking the total copolymer having structural units derived from the aromatic vinyl monomer and structural units derived from the unsaturated nitrile monomer as 100% by weight, it is preferably 5 to 45% by weight, more preferably 8 to 35% by weight, and still more preferably 10 to 30% by weight. When the structural units derived from the unsaturated nitrile monomer are within the above range, it is easy to obtain an extruded foam molding with a high foaming ratio.

[0034] Preferred embodiments of the copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer include styrene-acrylonitrile copolymers. The copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer may be used alone or in combination of two or more. 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. The copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer preferably has a weight average molecular weight higher than that of the vinyl chloride resin used, in terms of ensuring a high foaming ratio of the extrusion foam molded article. 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 in terms of polystyrene equivalent molecular weight by gel permeation chromatography. As the copolymer having a structural unit derived from an aromatic vinyl monomer and a structural unit derived from an unsaturated nitrile monomer, for example, Blendex869 manufactured by Galata can be used.

[0035] 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 foaming vinyl chloride resin particles according to an embodiment of the present invention is not particularly limited as long as the effects of the embodiment of the present invention are not impaired, but is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, still more preferably 5 to 35 parts by weight, and particularly preferably 8 to 30 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. By being in the range of the content, it becomes easy to obtain an extrusion foam molded article having a high foaming ratio, and the excellent flame retardant performance derived from the vinyl chloride resin is utilized.

[0036] Specific examples of the acrylic resin include, for example, (a) polymethyl methacrylate obtained by polymerizing methyl methacrylate and polymethyl acrylate obtained by polymerizing methyl acrylate, and (b) (i) methyl methacrylate or methyl acrylate, and (ii) an alkyl methacrylate having 2 to 8 carbon atoms in the alkyl group such as n-butyl methacrylate, an alkyl acrylate having 2 to 8 carbon atoms in the alkyl group such as ethyl acrylate, butylene, substituted styrene, acrylonitrile, and at least one monomer copolymerizable with methyl methacrylate or methyl acrylate. As the acrylic resin, it is preferable to use an acrylic resin in which the weight average molecular weight of the acrylic resin is higher than the weight average molecular weight of the vinyl chloride resin used, from the viewpoint of easily ensuring a high foaming ratio of the extrusion foam molded body. The weight average molecular weight of the acrylic resin is evaluated in terms of polystyrene equivalent molecular weight by gel permeation chromatography. As the acrylic resin, for example, Kane Ace PA-40 manufactured by Kaneka can be used.

[0037] The content of the acrylic resin in the foaming vinyl chloride resin particles according to one embodiment of the present invention is not particularly limited as long as it does not impair the effects of one embodiment of the present invention, but is preferably 1 to 50 parts by weight, more preferably 5 to 50 parts by weight, and still more preferably 8 to 30 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. By being in the range of the said content, it becomes easier to obtain an extrusion foam molded body having a higher foaming ratio, and the excellent flame retardant performance derived from the vinyl chloride resin is utilized.

[0038] The content of chlorinated polyethylene in the foaming vinyl chloride resin particles according to one embodiment of the present invention is not particularly limited as long as it does not impair the effects of one embodiment of the present invention, but is preferably 1 to 30 parts by weight, more preferably 2 to 25 parts by weight, and still more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the vinyl chloride resin. The chlorine content of chlorinated polyethylene is measured in accordance with JIS K7385 Method B.

[0039] In one embodiment of the present invention, the expandable vinyl chloride resin particles may contain a plasticizer, which can improve the foaming efficiency.

[0040] In one embodiment of the present invention, the plasticizer may be any known plasticizer, and is not particularly limited, but examples thereof include the following: phthalic acid-based plasticizers such as bis(2-ethylhexyl) phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), and bis(2-ethylhexyl) terephthalate; adipic acid-based plasticizers; phosphoric acid-based plasticizers such as trimethyl phosphate (TMP), triethyl phosphate (TEP), tributyl phosphate (TBP), tricresyl phosphate (TCP), and triphenyl phosphate (TPP); trimellitic acid-based plasticizers such as tris(2-ethylhexyl) trimellitate (TOTM); epoxy-based plasticizers such as epoxidized soybean oil; polyester-based plasticizers such as adipic acid-based polyester; fatty acid-based plasticizers; and other compounds that have a plasticizing effect on vinyl chloride resins, such as chlorinated paraffin. These plasticizers may be used alone or in combination of two or more.

[0041] In one embodiment of the present invention, from the viewpoint of gelling properties of vinyl chloride resins, the plasticizer is preferably at least one selected from the group consisting of phthalic acid plasticizers, phosphoric acid plasticizers, trimellitic acid plasticizers, epoxy plasticizers, and polyester resins, and more preferably a phthalic acid plasticizer and / or a phosphoric acid plasticizer. The use of a plasticizer that has good gelling properties of vinyl chloride resins tends to improve the retention of the physical blowing agent, making it easier to obtain foams with a high expansion ratio.

[0042] As one embodiment of the present invention, the content of the plasticizer is preferably 1.0 part by weight or more and 10.0 parts by weight or less, more preferably 2.0 parts by weight or more and 9.5 parts by weight or less, and still more preferably 3.0 parts by weight or more and 9.0 parts by weight or less with respect to 100 parts by weight of the vinyl chloride-based resin. By setting the content of the plasticizer within the above range, the resistance of the resin viscosity during foaming can be reduced, resulting in high foaming efficiency. Also, since the resin viscosity does not decrease too much, even when high magnification foaming occurs and the cell film becomes thin, the cell film can be prevented from breaking, enabling high magnification foaming. If the resin viscosity decreases too much, the cell film breaks during the foaming process, and the foaming agent volatilizes, resulting in a problem that the desired foaming ratio cannot be achieved.

[0043] The foaming vinyl chloride-based resin particles according to one embodiment of the present invention may contain other additives as necessary, as long as the effects of one embodiment of the present invention are not impaired. For example, flame retardants, stabilizers, lubricants, nucleating agents, foaming aids, antistatic agents, radiation heat transfer inhibitors, solvents, and colorants such as pigments and dyes can be mentioned.

[0044] As the flame retardant, known flame retardants can be used. Examples of the flame retardant include brominated flame retardants, phosphorus-based flame retardants, boron-based flame retardants, intumescent flame retardants such as melamine polyphosphate and ammonium polyphosphate, melamine-based flame retardants such as melamine cyanurate, and hydroxide compounds such as aluminum hydroxide and magnesium hydroxide. A flame retardant aid may be contained, and examples thereof include antimony oxide, zinc oxide, and zinc borate.

[0045] As the stabilizer, those conventionally used for vinyl chloride-based resins can be used. Examples of the stabilizer include tin-based stabilizers, antioxidants such as phenolic compounds, phosphorus-based compounds, and amine-based compounds, epoxy-based stabilizers, and zeolites. The amount of each stabilizer used in the vinyl chloride-based resin particles according to one embodiment of the present invention is not particularly limited as long as the effects of one embodiment of the present invention are not impaired, but it is preferably 10 parts by weight or less with respect to 100 parts by weight of the vinyl chloride-based resin.

[0046] Examples of the lubricant include waxes such as ester wax and polyethylene wax; and fatty acid metal salts such as calcium stearate and zinc stearate.

[0047] Examples of the nucleating agent include inorganic compounds such as silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, calcium carbonate, sodium hydrogen carbonate, zeolite, or talc.

[0048] Examples of the radiative 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, and aluminum.

[0049] Within a range that does not impair the effects of one embodiment of the present invention, other resins (thermoplastic resins or thermosetting resins) may be used in combination with the vinyl chloride-based resin. When the vinyl chloride-based resin and other resins are used in combination, the blending 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 with respect to 100 parts by weight of the vinyl chloride-based resin.

[0050] The shape of the particles of the foamable vinyl chloride-based resin particles according to one embodiment of the present invention is not particularly limited. The foamable vinyl chloride-based resin particles according to one embodiment of the present invention include not only general granular materials (for example, small rounded particles such as spherical, substantially spherical, convex lens-shaped, concave lens-shaped, and spindle-shaped), but also particles with dents. Incidentally, from the viewpoint of extrusion stability, the particle weight of the foamable vinyl chloride-based resin particles according to one embodiment of the present invention is preferably 1.3 to 10 mg / particle, more preferably 1.7 to 8 mg / particle, and still more preferably 2.5 to 7 mg / particle.

[0051] The foamable vinyl chloride-based resin particles according to one embodiment of the present invention preferably have a true density of 1100 kg / m 3 or more from the viewpoint of reducing the dissipation rate of the physical foaming agent from the foamable vinyl chloride-based resin particles, more preferably 1150 kg / m 3 or more, and still more preferably 1200 kg / m 3More preferably, 1250 kg / m 3 The true density referred to here can be determined by the measurement method described below.

[0052] The expandable vinyl chloride resin particles of one embodiment of the present invention can be produced, for example, by the following two production methods (first production method and second production method).

[0053] As an embodiment of the present invention, the first manufacturing method includes: (1-1) A vinyl chloride resin and, if necessary, various additives are heated, melted, and mixed in a known kneader such as an extruder, a roll processing machine, or a Banbury mixer; (1-2) The melt-kneaded product is granulated, and the resulting vinyl chloride resin particles are impregnated with a physical foaming agent in an autoclave to obtain expandable vinyl chloride resin particles.

[0054] As one embodiment of the present invention, the second manufacturing method includes: (2-1) A vinyl chloride resin and, if necessary, various additives are fed into an extruder, and the fed raw materials are melt-kneaded; (2-2) Dissolving and dispersing a physical foaming agent in the molten mixture using the extruder or a dispersing device downstream of the extruder; (2-3) A molten mixture (molten resin) of the foaming agent-containing vinyl chloride resin composition is extruded through a die having many small holes attached after the extruder into a cutter chamber filled with pressurized circulating water; (2-4) Immediately after the molten kneaded material (resin melt) is extruded, the molten kneaded material (resin melt) is cut by a rotary cutter in contact with the die, and the molten kneaded material is cooled and solidified by pressurized circulating water to obtain expandable vinyl chloride resin particles.

[0055] The second production method is preferred because it is easy to obtain the expandable vinyl chloride resin particles having the predetermined porosity of one embodiment of the present invention. In the second production method, the viscosity of the molten resin can be reduced by melt-kneading the physical foaming agent and the vinyl chloride resin, making it possible to lower the molding temperature of the vinyl chloride resin. As a result, there is an advantage in that thermal decomposition of the vinyl chloride resin and additives is less likely to occur.

[0056] In both the first and second production methods, it is preferable to thoroughly gel the vinyl chloride resin. If the gelation is insufficient, the physical foaming agent may dissipate rapidly when the resin is made into expandable vinyl chloride resin particles, and the physical foaming agent may not contribute much during extrusion foam molding. Therefore, it may be necessary to add an additional foaming agent during the resin melt-kneading process during extrusion foam molding.

[0057] In the first and second production methods, a general extruder can be used, specifically a single-screw extruder, a twin-screw extruder, a tandem extruder, etc. Examples of a tandem extruder include two connected single-screw extruders, or a twin-screw extruder connected to a single-screw extruder. Furthermore, an extruder may be used in combination with dispersion equipment such as a static mixer and / or a stirrer without a screw.

[0058] In the first and second production methods, the resin temperature during resin melt-kneading may affect the thermal decomposition of the vinyl chloride resin and various additives used in combination as needed. Therefore, the resin temperature of the molten resin is preferably 130 to 230°C, more preferably 140 to 220°C, and even more preferably 150 to 210°C. If the resin temperature of the molten resin is 130°C or higher, the resin viscosity of the molten resin decreases, enabling sufficient melt-kneading in a kneader such as an extruder. If the resin temperature of the molten resin exceeds 230°C, there is a risk of thermal decomposition of the vinyl chloride resin and various additives used in combination as needed. This may result in deterioration of the expandable vinyl chloride resin particles, potentially leading to a decrease in foaming performance.

[0059] The conditions of the granulation process in the first and second manufacturing methods will be described.

[0060] In an embodiment where the molten kneaded material (resin melt) is extruded from the die, the die is not particularly limited. For example, those having small holes with a diameter of preferably 0.3 mm to 2.0 mm, more preferably 0.4 mm to 1.5 mm can be mentioned.

[0061] In an embodiment where a sheet-like molten kneaded material is obtained using a roll processing machine or the like, after cooling the obtained sheet, an example is granulating sheet-like vinyl chloride resin particles using cutting equipment such as a cutter or a shredder. Incidentally, the thickness of the sheet-like vinyl chloride resin particles at this time can be adjusted by adjusting the clearance of the roll processing machine, which is the kneading equipment, or by further pressing the obtained sheet.

[0062] In the second manufacturing method, the tip pressure of the extruder attached upstream of the die is preferably 4 to 20 MPa, more preferably 6 to 18 MPa, and even more preferably 7 to 15 MPa. The extruder tip pressure is the value measured by a pressure sensor attached to the tip of the extruder. When two or more extruders are attached upstream of the die, the tip pressure of the most downstream extruder is taken as the extruder tip pressure in this specification. If the extruder tip pressure is 4 MPa or more, the dissolution and dispersion of the physical foaming agent in the resin during melt kneading becomes easy, and foaming vinyl chloride resin particles can be stably obtained. On the other hand, if the extruder tip pressure is 20 MPa or less, the shear heat generation during melt kneading can be suppressed, and the thermal decomposition of the vinyl chloride resin and various additives used in combination as necessary is less likely to occur.

[0063] In the second production method, the temperature of the molten resin (resin melt) immediately before extrusion through the die is preferably Tg + 20°C or higher, more preferably Tg + 20°C to Tg + 130°C, even more preferably Tg + 30°C to Tg + 110°C, and particularly preferably Tg + 40°C to Tg + 90°C, where Tg is the glass transition temperature of the resin without a physical blowing agent. The glass transition temperature of vinyl chloride resins increases with increasing chlorine content. Therefore, it is preferable to appropriately adjust the temperature of the molten resin (resin melt) immediately before extrusion through the die according to the chlorine content of the vinyl chloride resin used. If the temperature of the molten resin (resin melt) immediately before extrusion through the die is Tg + 20°C or higher, the viscosity of the extruded molten resin (resin melt) is reduced, which reduces the risk of clogging of the die holes and substantially prevents a decrease in the die hole aperture ratio. This prevents the resulting expandable vinyl chloride resin particles from becoming distorted or irregular in shape. On the other hand, if the temperature of the molten resin (resin melt) immediately before being extruded from the die is Tg+130°C or lower, the extruded molten resin (resin melt) will be more likely to solidify, making it less likely for the molten resin (resin melt) to wrap around the rotating cutter, and allowing the molten resin (resin melt) to be cut stably.

[0064] Here, "resin without foaming agent" refers to a resin containing vinyl chloride resin and processing aids and additives (other than physical foaming agents) that are used in combination as needed.

[0065] In the second production method, the cutting device for cutting the molten resin (resin melt) extruded into the circulating pressurized cooling water is not particularly limited. Examples of the cutting device include a device that cuts the molten resin (resin melt) into small pellets using a rotary cutter that comes into contact with a die, and transfers the resulting expandable vinyl chloride resin particles to a centrifugal dehydrator for dehydration and aggregation without foaming them in the pressurized circulating cooling water.

[0066] The conditions for the pressurized circulating cooling water should be adjusted depending on the type of vinyl chloride resin, additives, physical foaming agent, etc., and / or the content of each component. The conditions for the pressurized circulating cooling water are preferably such that foaming of the molten resin (resin melt) extruded from the die is suppressed and the molten resin (resin melt) is stably cut by the cutter. Specifically, the temperature condition for the pressurized circulating cooling water is preferably 40°C to 99°C, more preferably 50 to 90°C.

[0067] The pressure condition of the pressurized circulating cooling water is preferably adjusted so that the expansion ratio of the resulting expandable vinyl chloride resin particles is 1.0 to 1.25 times. The expansion ratio of the expandable vinyl chloride resin particles is determined based on the true density (kg / m) of the base resin. 3 ) is the true density (kg / m 3 The true density of the base resin and expandable polyvinyl chloride resin particles referred to here is calculated by submerging a weight W (kg) of polyvinyl chloride resin pellets or expandable polyvinyl chloride resin particles in a measuring cylinder containing ethanol, and calculating the volume V (m 3 Specifically, it can be determined by the measurement method described below.

[0068] Although it depends on the type of 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.

[0069] In the first production method, the conditions and equipment for impregnating the vinyl chloride resin particles with the physical foaming agent may be the same as those generally used, and may be set appropriately.

[0070] The expandable vinyl chloride resin particles according to the present invention can be used to continuously produce extruded foams having a high expansion ratio by melt-extrusion foaming in an extruder. The expandable vinyl chloride resin particles may be used alone or in combination with other resins.

[0071] Known devices and equipment can be used for extrusion foam molding. For example, expandable vinyl chloride resin particles, and optionally other resins and various additives, are fed into an extruder, melt-kneaded in the extruder, and the foaming agent-containing molten resin is extruded from the tip of the extruder to a die for foaming, followed by cooling to produce an extruded foam. An injection foaming device may also be used. A physical foaming agent may be newly injected during the melt-kneading process in the extruder.

[0072] By extrusion foam molding the expandable vinyl chloride resin particles according to the present invention, it is possible to obtain extruded foam molded articles with a high expansion ratio in various shapes such as plates, sheets, rods, and tubes. These foamed articles can be used for building materials, cushioning materials, trays for transporting electronic components, heat insulation materials, joint materials, pipe insulation materials, foam pipe materials, embankments, insulation materials for lithium ion batteries, returnable boxes, shock absorbing materials, sandwich panel core materials, ceiling materials, partitions, automobile interior materials, railway vehicle components, ship components, electric wire and cable covering materials, heat insulating siding, substrates for panel wallpaper, door core materials, wood substitute boards, decorative panels, wallpaper, flooring materials, sound absorbing materials, soundproofing materials, sporting goods, protective materials, housing components, vibration damping materials, cushioning materials, filtration materials, and the like.

[0073] One embodiment of the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. An embodiment obtained by appropriately combining the technical means disclosed in different embodiments is also included in the technical scope of one embodiment of the present invention. [Example]

[0074] 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.

[0075] The measurement and evaluation methods used in the following examples and comparative examples are as follows.

[0076] <Porosity evaluation of expandable polyvinyl chloride resin particles> Using the obtained foamed vinyl chloride resin particles as a sample, porosity evaluation was carried out under the following conditions using an AutoPore IV 9500 (manufactured by Micromeritics, USA).

[0077] 0.35 g of the foamed vinyl chloride resin particles was weighed as a sample and then added to the cell described below. The cell used was a cell for powders, with a sample chamber volume of 5 cc, a maximum measurement volume of 0.366 cc, a total stem volume of 0.392 cc, a maximum mercury head pressure of 4.45 psia, a cell constant of 11.117 μL / pF, an outer dimension I (measurement stem length) of 215 mm, an H (total stem length) of 230 mm, and a D (stem diameter) of 1.473 mm. Also, the Correction method was set to None and the measurement was carried out without correction. The cell with the sample was evacuated to 50 μmHg and further evacuated for 5 minutes (after maintaining the state of 50 μmHg for 5 minutes, mercury was introduced for evaluation).

[0078] After filling the evacuated cell with mercury at a pressure of 1.52 psia, pressure was applied to the mercury from 2 to 33000 psia for porosity evaluation. In the specification, the amount of mercury that penetrated into the sample within the pressure range of 20 to 33000 psia is referred to as porosity. The amount of mercury that penetrated into the pores of the foamed vinyl chloride resin particles, which are the sample, can be determined from the displacement of the mercury column in the sample container. The displacement is calculated from the change in capacitance between the mercury and the electrodes on the wall of the sample container. The AutoPore IV 9500 calculates the displacement of the mercury column from the measured capacitance using a capacitance-type detector and calculates the amount of mercury that penetrated into the sample (porosity).

[0079] The pressure profile during measurement was as follows. The pressure was increased to each of the described pressures (injection pressures), and the measurement was carried out with an equilibrium time of 10 seconds at each pressure.

[0080] 2 psia, 3 psia, 4 psia, 5.5 psia, 7 psia, 8.5 psia, 10.5 psia, 13 psia, 16 psia, 20 psia, 23 psia, 25 psia, 30 psia, 40 psia, 50 psia, 60 psia, 75 psia, 90 psia, 115 psia, 140 psia, 175 psia, 220 psia, 270 psia, 330 psia, 420 psia, 520 psia, 640 psia, 700 psia, 800 psia, 990 psia, 1200 psia, 1300 psia, 1400 psia, 1500 psia, 1600 psia, 1700 psia, 1900 psia, 2050 psia, 2200 psia, 2350 psia, 2500 psia, 2650 psia, 2700 psia, 2850 psia, 3000 psia, 3250 psia, 3500 psia, 3750 psia, 4000 psia, 4250 psia, 4500 psia, 4740 psia, 5000 psia, 5300 psia, 5500 psia, 5750 psia, 6000 psia, 6250 psia, 6500 psia, 6750 psia, 7000 psia, 7500 psia, 8000 psia, 8500 psia, 9000 psia, 9300 psia, 9600 psia, 10050 psia, 10500 psia, 11000 psia, 11500 psia, 12000 psia, 12600 psia, 13100 psia, 13650 psia, 14000 psia, 14340 psia, 14600 psia, 15000 psia, 15450 psia, 15800 psia, 16200 psia, 16650 psia, 17000 psia, 17350 psia, 17700 psia, 18100 psia, 18450 psia, 18800 psia, 19200 psia, 19800 psia, 20300 psia, 20800 psia, 21200 psia, 21650 psia, 22050 psia, 22650 psia, 23200 psia, 23750 psia, 24100 psia, 24650 psia, 25050 psia, 25450 psia, 25900 psia, 26450 psia, 26950 psia, 27400 psia, 27800 psia, 28250 psia, 29000 psia, 29500 psia30000 psia, 30450 psia, 30900 psia, 31300 psia, 31800 psia, 32350 psia, 33000 psia.

[0081] The pore radius during measurement is calculated by r = 2δcosθ / P. r is the pore radius, δ is the surface tension of mercury, θ is the contact angle of mercury, and P is the intrusion pressure. The pores present in the sample were calculated with a contact angle of mercury of 130° and a surface tension of 485 dynes / cm respectively. Both the intrusion contact angle and the extrusion contact angle were set to 130°, and the mercury density was set to 13.5335 g / ml.

[0082] <Measurement of the amount of blowing agent (volatile matter) contained in the foaming vinyl chloride resin particles> The weight W1 (g) of the foaming vinyl chloride resin particles was measured. Next, the foaming vinyl chloride resin particles were heated in an oven at 150 °C for 30 minutes, and then the heated foaming vinyl chloride resin particles were cooled in a desiccator at room temperature for 30 minutes. Then, the weight W2 (g) of the cooled foaming vinyl chloride resin particles was measured again. The weight difference (W1 - W2) before and after this heating was taken as the blowing agent content in the foaming vinyl chloride resin particles. In this specification, this blowing agent content may be referred to as volatile matter. The above-mentioned volatile matter was calculated by the following formula.

[0083] Volatile matter (wt%) = (W1 - W2) / W1 × 100 At the time of the extrusion foaming evaluation described later (i.e., on the same day as the extrusion foaming evaluation implementation date), the value (volatile matter) measured under the above conditions and calculated based on the above formula is referred to as the volatile matter during foaming (wt%).

[0084] <48-hour volatile matter and 48-hour volatile matter retention rate of the foaming vinyl chloride resin particles> Approximately 200 g of the foaming vinyl chloride resin particles immediately after production were placed in a sample bag with a chuck and stored in a constant temperature and humidity chamber at 23 °C × 50% RH for 48 hours. Then, they were measured and calculated under the same conditions as the measurement of the above-mentioned amount of blowing agent (volatile matter), and the calculated value (volatile matter) was taken as the volatile matter after 48 hours. Regarding the volatile matter retention rate after 48 hours, the value obtained by dividing the value of the volatile matter after 48 hours by the addition amount of the blowing agent was taken as the volatile matter retention rate after 48 hours.

[0085] <Measurement of particle weight of expandable polyvinyl chloride resin particles> Using an electronic balance capable of measuring to 0.01 mg, the weight of 100 randomly sampled expandable polyvinyl chloride resin particles was measured, and the particle weight was calculated using the following formula. Particle weight (mg) = [Weight (mg) of 100 expandable polyvinyl chloride resin particles] / 100

[0086] <Measurement of true density of expandable polyvinyl chloride resin particles> Foamable polyvinyl chloride resin particles with a weight of W (kg) are submerged in a measuring cylinder containing ethanol, and the volume V (m 3 ) was calculated using the following formula: True density (kg / m) of foamable vinyl chloride resin particles 3 )=(W / V)

[0087] <Measurement of true density of vinyl chloride resin pellets> A homogeneous mixture was obtained by blending (A-1) chlorinated vinyl chloride resin with auxiliary materials such as processing aids, stabilizers, and lubricants. The mixture was then melt-kneaded using an extruder to obtain vinyl chloride resin pellets. The vinyl chloride resin pellets with a weight of W (kg) were submerged in a measuring cylinder containing ethanol, and the volume V (m) was determined from the rise in the liquid level in the measuring cylinder (submersion method). 3 ) was calculated using the following formula: True density of vinyl chloride resin pellets (kg / m 3 )=(W / V)

[0088] Based on the above method, the true density of the vinyl chloride resin pellets measured was 1430 kg / m 3 It was.

[0089] <Measurement of magnification of extruded foam molded products> A test piece of approximately 1.5 g was prepared from each foam obtained in the Examples and Comparative Examples, and the weight W (g) of the test piece was measured. The test piece was then submerged in a measuring cylinder containing water, and the apparent volume Va (cm ) was calculated from the rise in the liquid level in the measuring cylinder (submersion method).3 ) was determined, and after calculating the foam density from the following formula, the expansion ratio was determined from the following formula. The true density of the resin was 1430 kg / m as described above 3 was used. Foam density (kg / m 3 ) = W / Va × 1000 Expansion ratio (times) = True density of resin / Foam density The raw materials used in the examples and comparative examples are shown below.

[0090] <Calculation of foaming efficiency> The value obtained by measuring the expansion ratio of the extrusion foamed molded body was divided by the value of the volatile content during foaming, and the resulting numerical value was calculated as the foaming efficiency.

[0091] (Vinyl chloride resin) (A-1) Chlorinated vinyl chloride resin [manufactured by Kaneka Corporation, H716S, average degree of polymerization 600, chlorine content 67.6% by weight]

[0092] (Processing aid) (B-1) Acrylic resin [manufactured by Kaneka Corporation, Kane Ace PA-40] (B-2) Styrene-acrylonitrile copolymer [manufactured by Galata, Blendex 869, weight average molecular weight 2.86 million, component ratio derived from acrylonitrile in the copolymer; 20% by weight]

[0093] (Blowing agent) (C-1) Normal pentane [manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., SP value: 7.0 ((cal / cm 3 ) 1 / 2 )] (C-2) Acetone [manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., SP value: 10.0 ((cal / cm 3 ) 1 / 2 )] (C-3) Ethyl chloride [manufactured by Nippon Special Chemical Industry Co., Ltd., SP value: 9.2 ((cal / cm 3 ) 1 / 2 )]

[0094] (Example 1) [Preparation of foaming vinyl chloride resin particles] A blend was obtained by adding 13 parts by weight of styrene-acrylonitrile copolymer (B-2) to 100 parts by weight of chlorinated vinyl chloride resin (A-1), 5 parts by weight of butyltin mercapto stabilizer, 3 parts by weight of lubricant (ester wax, polyethylene wax), 5 parts by weight of chlorinated polyethylene with a chlorine content of 35% by weight, and 5 parts by weight of bis(2-ethylhexyl) phthalate. This blend was blended to obtain a uniform blend. The blend was then melt-kneaded in an intermeshing co-rotating twin-screw extruder to obtain pellets with the above blend ratio. The resulting pellets are pellets of chlorinated vinyl chloride resin and are sometimes referred to as base resin. The resulting pellets were fed to a twin-screw extruder at a feed rate of 40 kg / hr and melt-kneaded. The twin-screw extruder used was an intermeshing co-rotating twin-screw extruder with a shaft diameter of 40 mm.

[0095] 8.7 parts by weight of normal pentane (C-1) and 3.8 parts by weight of acetone (C-2) were injected as blowing agents into a 40 mm diameter co-meshing twin-screw extruder per 100 parts by weight of the pellets. The molten mixture (resin melt) was then cooled through a continuation pipe attached to the tip of the twin-screw extruder, a single-screw extruder set at 160°C, a gear pump, and a diverter valve. The resin melt was then extruded at a rate of 45 kg / hr through a die set at 220°C and equipped with 30 small holes, each 1.0 mm in diameter and 3.5 mm in land length, attached downstream of the diverter valve. The extruder tip pressure was 15 MPa, and the resin temperature of the melt (i.e., the resin temperature of the resin melt at the extruder tip) was 155°C. Note that the extruder tip in the examples and comparative examples refers to the single-screw extruder tip. The extruded resin melt was cut and granulated using a rotary cutter in contact with the die, and transferred to a centrifugal dehydrator to obtain expandable vinyl chloride resin particles with a particle weight of 5.2 mg. The true density of the obtained expandable vinyl chloride resin particles was measured using the method described above in <Measurement of true density of expandable vinyl chloride resin particles>, and was found to be 1308 kg / m 3 It was.

[0096] The resulting expandable vinyl chloride resin particles were evaluated for 48-hour volatile content and 48-hour volatile content retention by the method described in <48-hour volatile content and 48-hour volatile content retention of expandable vinyl chloride resin particles>. The results are shown in Table 1.

[0097] The resulting expandable vinyl chloride resin particles were stored at 10°C for 7 days, and then the porosity was evaluated by the method described above in <Porosity Evaluation of Expandable Vinyl Chloride Resin Particles>. The results are shown in Table 1.

[0098] The resulting expandable vinyl chloride resin particles were fed into an extruder, melt-kneaded within the extruder, and the blowing agent-containing molten resin was extruded from the tip of the extruder into a die and cooled to obtain an extruded foam. The extruded foam was obtained using a 90mm diameter single-screw extruder, a gear pump attached to the extruder's tip, and a die set to 220°C with 30 small holes, each 1.0mm in diameter and 3.5mm in land length. The extruder and gear pump rotation speeds were adjusted to achieve a discharge rate of 45kg / h, a pressure across the gear pump of 13MPa, and the extruder temperature was set to achieve a resin temperature of 140°C at the die. The expansion ratio of the resulting extruded foam was measured using the method described in "Measurement of Expansion Ratio of Extruded Foam Molded Products." The volatile content of the expandable vinyl chloride resin particles used was also measured using the method described in "Measurement of the Amount of Blowing Agent (Volatile Content) Contained in Expandable Vinyl Chloride Resin Particles." The results are shown in Table 1.

[0099] Example 2 The same procedure as in Example 1 was repeated except that the blowing agents were changed to 6.25 parts by weight of normal pentane (C-1) and 6.25 parts by weight of ethyl chloride (C-3), the single-screw extrusion temperature was changed to 160°C, and the temperature of the pressurized circulating water was changed to 70°C. A pellet weight of 5.0 mg and a true density of 1302 kg / m were obtained. 3 The pressure at the tip of the extruder was 13 MPa, and the resin temperature of the molten material was 166°C. The resulting expandable vinyl chloride resin particles were subjected to the same procedures as in Example 1 to evaluate the volatile content after 48 hours, the volatile content retention after 48 hours, and the porosity. The resulting expandable vinyl chloride resin particles were subjected to an extrusion foaming evaluation and measurement of the volatile content of the expandable vinyl chloride resin particles in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0100] Example 3 In Example 1, the styrene-acrylonitrile copolymer (B-2) was 13 parts by weight, the acrylic resin (B-1) was 10 parts by weight, bis(2-ethylhexyl) phthalate was 0 part by weight, normal pentane (C-1) was 11.7 parts by weight and acetone (C-2) was 0.8 parts by weight as the blowing agent, the temperature setting of the single-screw extruder was changed to 185°C, and the temperature of the pressurized circulating water was changed to 70°C. The same procedure as in Example 1 was repeated to obtain a pellet weight of 2.9 mg and a true density of 1344 kg / m. 3 The pressure at the tip of the extruder was 12 MPa, and the resin temperature of the molten material was 186°C. The resulting expandable vinyl chloride resin particles were evaluated in the same manner as in Example 1 for the volatile content after 48 hours, the volatile content retention after 48 hours, the porosity, and the extrusion foaming.

[0101] The evaluation results are shown in Table 1. The resulting expandable vinyl chloride resin particles were subjected to an extrusion foaming evaluation and measurement of the volatile content of the expandable vinyl chloride resin particles in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0102] (Comparative Example 1) Expandable vinyl chloride resin particles with a particle weight of 2.0 mg were obtained in the same manner as in Example 3, except that the blowing agent was changed to 13.1 parts by weight of normal pentane (C-1). The extruder tip pressure was 12 MPa, and the resin temperature of the molten material was 187°C. The resulting expandable vinyl chloride resin particles were evaluated in the same manner as in Example 1 for the volatile content after 48 hours, the volatile content retention after 48 hours, the porosity, and the extrusion foaming.

[0103] The evaluation results are shown in Table 1. The resulting expandable vinyl chloride resin particles were subjected to an extrusion foaming evaluation and measurement of the volatile content of the expandable vinyl chloride resin particles in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0104] (Comparative Example 2) The expandable vinyl chloride resin particles obtained in Example 1 were left to stand in an environment of 23°C x 50% RH until the volatile content reached 0.7 wt%. Extrusion foaming evaluation was performed using the expandable vinyl chloride resin particles with a volatile content of 0.7 wt%. The results are shown in Table 1.

[0105] [Table 1]

Claims

1. Based on the total amount of vinyl chloride resin and physical foaming agent being 100% by weight, containing 1 - 20% by weight of physical foaming agent, with a porosity of 7.5 (ml / 100g) or less, And a particle weight of 1.3 - 10 mg / particle, expandable vinyl chloride resin particles for extrusion molding.

2. Based on the total amount of vinyl chloride resin and physical foaming agent being 100% by weight, containing 1 - 20% by weight of physical foaming agent, with a porosity of 7.5 (ml / 100g) or less, Expandable vinyl chloride resin particles for extrusion molding, containing a chlorinated vinyl chloride polymer with a chlorine content of 60% by weight or more and 75% by weight or less.

3. Based on the total amount of vinyl chloride resin and physical foaming agent being 100% by weight, containing 1 - 20% by weight of physical foaming agent, with a porosity of 7.5 (ml / 100g) or less, Expandable vinyl chloride resin particles for extrusion molding, containing a chlorinated vinyl chloride polymer with an average degree of polymerization of 300 or more and 3000 or less.

4. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1 to 3, containing a physical foaming agent with a solubility index (SP value) of 7.4 or less.

5. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1 to 4, with a foaming ratio (times) / volatile content during foaming (weight%) of 2.0 or more.

6. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1 to 5, wherein the physical foaming agent contains at least one saturated hydrocarbon with 4 - 6 carbon atoms.

7. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1 to 6, wherein the physical foaming agent contains a ketone and / or a halogenated alkyl.

8. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1, 3 to 7, containing a chlorinated vinyl chloride polymer with a chlorine content of 60% by weight or more and 75% by weight or less.

9. The expandable vinyl chloride resin particles for extrusion molding according to any one of Claims 1, 4 to 8, containing a chlorinated vinyl chloride polymer with an average degree of polymerization of 300 or more and 3000 or less.

10. The expandable vinyl chloride resin particles for extrusion molding according to Claim 6, wherein the saturated hydrocarbon with 4 - 6 carbon atoms contains pentane.

11. The foamed vinyl chloride resin particles for extrusion molding according to any one of claims 1 to 10, containing at least one selected from the group consisting of a copolymer having an aromatic vinyl monomer and an unsaturated nitrile as structural units, an acrylic resin, and chlorinated polyethylene.

12. The foamed vinyl chloride resin particles for extrusion molding according to any one of claims 1 to 11, containing at least one selected from the group consisting of a phthalic acid plasticizer, a phosphoric acid plasticizer, a trimellitic acid plasticizer, an epoxy plasticizer, and a polyester plasticizer.

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