Vinyl chloride resin composition for extruded foam molded body and extruded foam molded body

Abstract

Provided is a vinyl chloride resin composition that makes it possible to provide an extruded foam body that has a high expansion ratio. The vinyl chloride resin composition includes specific amounts of each of a vinyl chloride resin (A), a copolymer (B) that is 20–85 wt% α-methylstyrene units, a processing aid (C) that has a specific weight average molecular weight and includes (i) a (meth)acrylic polymer and / or (ii) a copolymer that has an aromatic vinyl unit and an unsaturated nitrile unit, and a foaming agent (D).

Description

Vinyl chloride resin composition for extruded foam molded products, and extruded foam molded products

[0001] The present invention relates to a vinyl chloride resin composition for use in extruded foam molded articles, and to extruded foam molded articles.

[0002] Vinyl chloride resins are known to have excellent flame retardancy, and extruded vinyl chloride resin foams using vinyl chloride resins as a base resin have been known (see, for example, Patent Document 1).

[0003] Furthermore, compositions containing a styrene resin and a foaming agent are known as thermoplastic resin compositions for foam molding to obtain extruded foam molded articles (for example, Patent Documents 2 and 3).

[0004] Japanese Patent Application Publication No. 7-3066 Japanese Patent Application Publication No. 2008-150476 Japanese Patent Application Publication No. 2009-91553

[0005] However, the above-mentioned conventional techniques are not sufficient from the viewpoint of obtaining extruded foams with a high expansion ratio, and there is room for further improvement.

[0006] One embodiment of the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a novel vinyl chloride resin composition that can provide an extruded foam with a high expansion ratio.

[0007] The present inventors have conducted extensive research to solve the above problems and have completed the present invention.

[0008] A vinyl chloride resin composition for extruded foam moldings according to one embodiment of the present invention comprises a vinyl chloride resin (A), a copolymer (B), a processing aid (C), and a blowing agent (D), wherein the copolymer (B) contains 20 to 85% by weight of α-methylstyrene units as structural units, per 100% by weight of the copolymer (B), and has a glass transition temperature of 90°C or higher, the content of the copolymer (B) is 5.0 to 75.0 parts by weight, based on 100 parts by weight of the total of the vinyl chloride resin (A) and the copolymer (B), the processing aid (C) comprises (i) a (meth)acrylic polymer and / or (ii) a copolymer having structural units comprising aromatic vinyl units and unsaturated nitrile units, and the weight average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000, The content of the processing aid (C) is 5.0 parts by weight to 30.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) combined.

[0009] According to one embodiment of the present invention, it is possible to provide a novel vinyl chloride resin composition that can provide an extruded foam with a high expansion ratio.

[0010] An 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, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0011] In this specification, a "structural unit derived from an X monomer" contained in a polymer, copolymer, or resin may be referred to as an "X unit."

[0012] Unless otherwise specified in this specification, the structural unit is X １ Units and X ２ Units, ... and X ｎ A copolymer containing units (n is an integer of 2 or more) is referred to as "X １ / X ２ / ・・・ / X ｎ Also referred to as "copolymer". X １ / X ２ / ・・・ / X ｎ Unless otherwise specified, the copolymer is not particularly limited in polymerization mode, and may be a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer.

[0013] Herein, the "vinyl chloride resin composition for extruded foam molded products" may also be referred to as the "vinyl chloride resin composition" or simply as the "composition." Herein, the "vinyl chloride resin composition for extruded foam molded products according to one embodiment of the present invention" may also be referred to as the "composition." Herein, the "extruded foam molded product according to one embodiment of the present invention" may also be referred to as the "extruded foam molded product."

[0014] [1. Vinyl chloride resin composition] A vinyl chloride resin composition for extruded foam moldings according to one embodiment of the present invention comprises a vinyl chloride resin (A), a copolymer (B), a processing aid (C), and a blowing agent (D), wherein the copolymer (B) is a copolymer containing 20 to 85% by weight of α-methylstyrene units as structural units in 100% by weight of the copolymer (B) and having a glass transition temperature of 90°C or higher, and the content of the copolymer (B) is 100% by weight of the total of the vinyl chloride resin (A) and the copolymer (B). The content of the processing aid (C) is 5.0 parts by weight to 75.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the processing aid (C) includes (i) a (meth)acrylic polymer and / or (ii) a copolymer having an aromatic vinyl unit and an unsaturated nitrile unit as structural units, the weight average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000, and the content of the processing aid (C) is 5.0 parts by weight to 30.0 parts by weight per 100 parts by weight of the total of the vinyl chloride resin (A) and the copolymer (B).

[0015] The present composition has the above-mentioned constitution and therefore has the advantage of being able to provide an extruded foam with a high expansion ratio.

[0016] (Vinyl chloride resin (A)) The vinyl chloride resin (A) is not particularly limited as long as it is a polymer or copolymer obtained using a vinyl chloride monomer. In other words, the vinyl chloride resin (A) is not particularly limited as long as it contains a vinyl chloride unit.

[0017] Examples of the vinyl chloride resin (A) include (a) a homopolymer of vinyl chloride and (b) a copolymer of (i) vinyl chloride and (ii) another monomer copolymerizable with vinyl chloride. Examples of the other monomer copolymerizable with vinyl chloride include ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic esters, and vinyl ethers. The other monomer copolymerizable with vinyl chloride may be used alone or in combination of two or more.

[0018] The vinyl chloride resin (A) preferably contains 50% by weight or more of vinyl chloride units, more preferably more than 50% by weight, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the resin. The vinyl chloride resin (A) may contain 100% by weight of vinyl chloride units, based on 100% by weight of the resin. In other words, the vinyl chloride resin (A) may be composed only of vinyl chloride units, or may be, for example, a homopolymer of vinyl chloride. In this specification, the term "vinyl chloride units" also includes "chlorinated vinyl chloride units" obtained by chlorinating vinyl chloride units.

[0019] The average degree of polymerization of the vinyl chloride resin (A) is not particularly limited. The average degree of polymerization of the vinyl chloride resin (A) is preferably 400 to 1,300, more preferably 450 to 1,200, more preferably 500 to 1,000, even more preferably 530 to 900, and particularly preferably 550 to 800. This configuration tends to produce extruded foam molded articles with a high expansion ratio. The average degree of polymerization of the vinyl chloride resin (A) is a value measured in accordance with JIS K6720-2.

[0020] The vinyl chloride resin (A) also includes a chlorinated vinyl chloride resin obtained by chlorinating (a) a homopolymer of vinyl chloride and / or (b) a copolymer of (i) vinyl chloride and (ii) another monomer copolymerizable with vinyl chloride. From the viewpoint of cell retention during extrusion foam molding, the vinyl chloride resin (A) preferably contains a chlorinated vinyl chloride resin.

[0021] Chlorinated vinyl chloride resins are usually produced using the various vinyl chloride resins described above as raw materials by the following methods (a) and (b): (a) a method of chlorination in an aqueous medium, in which a vinyl chloride resin is dispersed in an aqueous medium and chlorine is supplied to the aqueous medium, and the resulting mixture is (i) irradiated with a mercury lamp to perform photochlorination, or (ii) chlorinated by heating the resulting mixture; and (b) a method of chlorination in a gas phase, in which the vinyl chloride resin is chlorinated in a gas phase under irradiation with a mercury lamp.

[0022] The average degree of polymerization of the chlorinated vinyl chloride resin is considered to be substantially the same as the average degree of polymerization of the vinyl chloride resin before chlorination.

[0023] The chlorine content of the chlorinated vinyl chloride resin is preferably 60% by weight to 75% by weight, more preferably 64% by weight to 70% by weight, since this improves the foamability of the resulting composition. The greater the chlorine content of the chlorinated vinyl chloride resin, the more likely it is that an extruded foam molded article will have a higher expansion ratio. The smaller the chlorine content of the chlorinated vinyl chloride resin, the more likely it is that the melt viscosity of the composition will decrease, resulting in better processability during extrusion. The chlorine content of the chlorinated vinyl chloride resin and the vinyl chloride resin is a value measured in accordance with JIS K7385 Method B.

[0024] In one embodiment of the present invention, the vinyl chloride resin (A) may be one selected from the group consisting of the various vinyl chloride resins described above and various chlorinated vinyl chloride resins obtained by chlorinating the various vinyl chloride resins described above, or two or more selected from this group may be used in combination.

[0025] The content of the vinyl chloride resin (A) in the composition is not particularly limited. The content of the vinyl chloride resin (A) in the composition is preferably 10.0 to 70.0 parts by weight, more preferably 15.0 to 65.0 parts by weight, even more preferably 18.0 to 62.0 parts by weight, and particularly preferably 20.0 to 60.0 parts by weight, per 100 parts by weight of the composition. When the content of the vinyl chloride resin (A) in 100 parts by weight is 10.0 parts by weight or more, the composition has the advantage of an excellent balance between cost and foaming performance. When the content of the vinyl chloride resin (A) in 100 parts by weight is 70.0 parts by weight or less, the composition has the advantage of an excellent balance between fluidity and foamability during extrusion foam molding.

[0026] (Copolymer (B)) Copolymer (B) is a copolymer that contains 20 wt % to 85 wt % of α-methylstyrene units as structural units, based on 100 wt % of copolymer (B), and has a glass transition temperature (hereinafter sometimes referred to as "Tg") of 90°C or higher. Copolymer (B) can have the function of increasing the Tg of the composition. In the course of extensive research, the present inventors independently discovered that by increasing the Tg of a composition, extruded foams having a high expansion ratio can be obtained from the composition. In other words, by including copolymer (B), the present composition has the advantage of being able to provide extruded foams having a high expansion ratio.

[0027] Copolymer (B) preferably contains 20 wt% to 85 wt%, more preferably 25 wt% to 80 wt%, more preferably 30 wt% to 80 wt%, more preferably 35 wt% to 75 wt%, more preferably 40 wt% to 75 wt%, more preferably 45 wt% to 75 wt%, more preferably 50 wt% to 75 wt%, even more preferably 55 wt% to 75 wt%, and particularly preferably 60 wt% to 75 wt% of α-methylstyrene units per 100 wt% of copolymer (B). This configuration provides the composition with the advantage of excellent cell retention during extrusion foam molding. Furthermore, copolymer (B) contains 20 wt% or more α-methylstyrene units per 100 wt%, providing the advantage of good compatibility (easy compatibility) with vinyl chloride resin (A). As a result, the copolymer (B) has the advantage of easily increasing the Tg of the composition.

[0028] The copolymer (B) may contain, as a structural unit other than the α-methylstyrene unit, a structural unit copolymerizable with α-methylstyrene and derived from a monomer other than α-methylstyrene. Examples of the monomer copolymerizable with α-methylstyrene other than α-methylstyrene include aromatic vinyl monomers other than α-methylstyrene, conjugated diene monomers, unsaturated nitrile monomers, and (meth)acrylic monomers. The monomer other than α-methylstyrene may be used alone or in combination of two or more.

[0029] Examples of aromatic vinyl monomers other than α-methylstyrene include (i) styrene, and (ii) styrene derivatives other than α-methylstyrene, such as ethylstyrene, p-methylstyrene, and halogenated styrenes. Examples of the halogenated styrenes include monobromostyrene, dibromostyrene, tribromostyrene, and chlorostyrene.

[0030] Examples of the conjugated diene monomer include 1,3-butadiene, isoprene (also known as 2-methyl-1,3-butadiene), and 2-chloro-1,3-butadiene.

[0031] Examples of the unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.

[0032] Examples of the (meth)acrylic monomer include: (i) (meth)acrylic acid; (ii) alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (iii) aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; and (iv) hydroxyalkyl (meth)acrylates. (v) glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; (vi) alkoxyalkyl (meth)acrylates; (vii) allyl alkyl (meth)acrylates such as allyl (meth)acrylate and allyl alkyl (meth)acrylate; (viii) polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; and the like. In this specification, "(meth)acrylic" means "methacrylic and / or acrylic." That is, in this specification, "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid," and "(meth)acrylate" means "acrylate and / or methacrylate." For example, "methyl (meth)acrylate" means "methyl acrylate and / or methyl methacrylate."

[0033] The glass transition temperature of the copolymer (B) is 90°C or higher. When the glass transition temperature of the copolymer (B) is 90°C or higher, the present composition has the advantage of being able to provide an extruded foam with a high expansion ratio. From the viewpoint of cell retention during extrusion foam molding, the glass transition temperature of the copolymer (B) is preferably 95°C or higher, more preferably 100°C or higher, more preferably 105°C or higher, more preferably 110°C or higher, more preferably 115°C or higher, even more preferably 120°C or higher, and particularly preferably 125°C or higher.

[0034] When the monomers used in the production of a polymer are known, the glass transition temperature (Tg) of the polymer can be calculated using the FOX equation (Equation 1) shown below: 1 / Tg = w １ / Tg １ +w ２ / Tg ２ +...+w ｎ / Tg ｎ (Formula 1); where Tg １ , Tg ２ , ..., Tg ｎ are the Tg (K) of the homopolymer of the components (i.e., the monomers used in the production of the polymer) 1, 2, ..., n, respectively. １ , w ２ ,...,w ｎ are the weight fractions of the components constituting the polymer (i.e., the monomers used in producing the polymer) 1, 2, ..., n, respectively. The Tg of a homopolymer can be, for example, the value described in "Polymer Handbook Fourth Edition" by J. Brand, published by Wiley in 1998. The Tg of a polymer may be calculated by differential thermal analysis or differential scanning calorimetry.

[0035] The content of copolymer (B) in the composition is 5.0 to 75.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B). When the content of copolymer (B) per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) is 5.0 parts by weight or more, the composition has the advantage of excellent cell retention during extrusion foam molding. When the content of copolymer (B) per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) is 75.0 parts by weight or less, the composition has the advantage of being able to obtain a melt viscosity suitable for extrusion foam molding. In order to further enjoy these advantages, the content of copolymer (B) in the composition is more preferably 10.0 to 70.0 parts by weight, more preferably 15.0 to 65.0 parts by weight, still more preferably 20.0 to 63.0 parts by weight, and particularly preferably 22.0 to 60.0 parts by weight, per 100 parts by weight of the vinyl chloride resin (A) and copolymer (B) in total.

[0036] The content of copolymer (B) in the composition is preferably 3.0 to 65.0 parts by weight, more preferably 5.0 to 60.0 parts by weight, more preferably 10.0 to 55.0 parts by weight, even more preferably 15.0 to 50.0 parts by weight, and particularly preferably 17.0 to 47.0 parts by weight, per 100 parts by weight of the composition. When the content of copolymer (B) per 100 parts by weight is 3.0 parts by weight or more, the composition has the advantage of excellent cell retention during extrusion foam molding. When the content of copolymer (B) per 100 parts by weight is 65.0 parts by weight or less, the composition has the advantage of being able to obtain a melt viscosity suitable for extrusion foam molding.

[0037] (Method for Producing Copolymer (B)) As a method for producing copolymer (B), in other words, a method for polymerizing copolymer (B), a known method can be used and is not particularly limited. As a method for polymerizing copolymer (B), for example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. can be used, but emulsion polymerization is preferably used.

[0038] The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Furthermore, dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may also be used as the emulsifier (dispersant). The emulsifier (dispersant) may be used alone or in combination of two or more.

[0039] When emulsion polymerization is employed, a thermally decomposable initiator can be used as the radical polymerization initiator, such as known initiators such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0040] Redox initiators can also be used as radical polymerization initiators. The redox initiators are initiators that combine (a) a peroxide, such as an organic peroxide or an inorganic peroxide, with (b) optionally a reducing agent, such as sodium formaldehyde sulfoxylate or glucose, and optionally a transition metal salt, such as iron (II) sulfate, and optionally a chelating agent, such as disodium ethylenediaminetetraacetate, and optionally a phosphorus-containing compound, such as sodium pyrophosphate. Examples of organic peroxides include t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Examples of inorganic peroxides include hydrogen peroxide, potassium persulfate, and ammonium persulfate. The peroxide, reducing agent, transition metal salt, chelating agent, and phosphorus-containing compound may each be used alone or in combination of two or more.

[0041] When a redox initiator is used, polymerization can be carried out even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set over a wide range. Therefore, it is preferable to use a redox initiator. Among redox initiators, redox initiators using organic peroxides such as cumene hydroperoxide, dicumyl peroxide, paramenthane hydroperoxide, and t-butyl hydroperoxide as the peroxide are preferred. The amount of the initiator used, and when a redox initiator is used, the amounts of the reducing agent, transition metal salt, chelating agent, etc. used can be within known ranges.

[0042] In the polymerization of the copolymer (B), known surfactants and chain transfer agents may also be used.

[0043] When copolymer (B) is produced by emulsion polymerization, a latex containing copolymer (B) (e.g., an aqueous latex) can be obtained. Copolymer (B) can be obtained by separating copolymer (B) from the latex containing copolymer (B). The method for separating copolymer (B) from the latex containing copolymer (B) is not particularly limited, but examples include salting out copolymer (B) using an acid, a metal salt, or the like, and precipitating copolymer (B) using an organic solvent. Copolymer (B) separated from the latex containing copolymer (B) may be washed and further dried. A powder of copolymer (B) (also referred to as "powder") can be obtained by separating copolymer (B) from the latex containing copolymer (B), washing it, and further drying it. Alternatively, a powder of copolymer (B) can be obtained by spray-drying the latex containing copolymer (B).

[0044] (Carrier (B)) The copolymer (B) may be produced together with a polymer other than the copolymer (B) in order to improve the granulation property during production. In this specification, "a polymer other than the copolymer (B) that is produced together with the copolymer (B) in order to improve the granulation property of the copolymer (B)" may also be referred to as "carrier (B)".

[0045] The carrier (B) is not particularly limited, but a (meth)acrylic polymer obtained by polymerizing a (meth)acrylic monomer is preferably used.

[0046] (Complex (B)) A case where the copolymer (B) is produced together with the carrier (B) (hereinafter also referred to as "Case A") will be described. In Case A, it is preferable to polymerize the copolymer (B) and then polymerize the carrier (B) in the presence of the copolymer (B). In Case A, when the copolymer (B) is obtained, for example, by emulsion polymerization, it is particularly preferable to produce (polymerize) the copolymer (B) and then produce (polymerize) the carrier (B) in a latex containing the copolymer (B). When the carrier (B) is produced (polymerized) in a latex containing the copolymer (B), a composite containing the copolymer (B) and the carrier (B) (or consisting of the copolymer (B) and the carrier (B)) can be obtained. In the composite, the carrier (B) is preferably present on the outside of the copolymer (B) and present so as to cover at least a portion of the copolymer (B). In the composite, the carrier (B) may cover the entire copolymer (B) or may be impregnated into the particulate copolymer (B). In the composite, it is preferable that the copolymer (B) and the carrier (B) are not chemically bonded to each other. In this specification, a "composite containing the copolymer (B) and the carrier (B) (or consisting of the copolymer (B) and the carrier (B))" may also be referred to as a "composite (B)."

[0047] In Case A, the composition may further comprise a carrier (B). When the composition further comprises a carrier (B), the weight-average molecular weight of the composite (B) comprising the copolymer (B) and the carrier (B) is not particularly limited, but is preferably 20,000 to 800,000, more preferably 25,000 to 400,000, more preferably 50,000 to 250,000, even more preferably 60,000 to 200,000, and particularly preferably 65,000 to 130,000. When the composition further comprises a carrier (B) and the weight-average molecular weight of the composite (B) is 20,000 or more, the composition has the advantage of excellent cell retention during extrusion foam molding. When the composition further comprises a carrier (B) and the weight-average molecular weight of the composite (B) is 800,000 or less, the composition has the advantage of excellent dispersibility of the composite (B) (i.e., the copolymer (B)) in the composition. When the composition further contains a carrier (B), the weight average molecular weight of the composite (B) may be less than 1,500,000 or more than 8,000,000. The method for measuring the weight average molecular weight of a resin, polymer, copolymer, or composite herein is described in detail in the Examples below.

[0048] On the other hand, when copolymer (B) is produced solely from copolymer (B) without being produced together with carrier (B), the present composition does not contain carrier (B). When the present composition does not contain carrier (B), the weight-average molecular weight of copolymer (B) is not particularly limited, but is preferably 20,000 to 800,000, more preferably 25,000 to 400,000, more preferably 50,000 to 250,000, even more preferably 60,000 to 200,000, and particularly preferably 65,000 to 130,000. When the present composition does not contain carrier (B) and the weight-average molecular weight of copolymer (B) is 20,000 or more, the present composition has the advantage of excellent cell retention during extrusion foam molding. When the present composition does not contain carrier (B) and the weight-average molecular weight of copolymer (B) is 800,000 or less, the present composition has the advantage of good dispersibility of copolymer (B) in the present composition. When the composition does not contain a carrier (B), the weight average molecular weight of the copolymer (B) may be less than 1,500,000 and may be greater than 8,000,000.

[0049] In one embodiment of the present invention, the copolymer (B) may be a copolymer that (i) contains 20% by weight to 85% by weight of α-methylstyrene units as structural units, based on 100% by weight of the copolymer, (ii) has a Tg of 90°C or higher, and (iii) has a weight average molecular weight of less than 1,500,000 or more than 8,000,000.

[0050] (Processing Aid (C)) The processing aid (C) includes (i) a (meth)acrylic polymer and / or (ii) a copolymer having structural units of aromatic vinyl units and unsaturated nitrile units. The processing aid (C) may be composed solely of a (meth)acrylic polymer and / or (ii) a copolymer having structural units of aromatic vinyl units and unsaturated nitrile units. The weight-average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000. The processing aid (C) may have the function of increasing the melt tension of the composition, which can be an important parameter for foam molding of the composition. In other words, by containing both the copolymer (B) capable of increasing Tg and the processing aid (C) capable of increasing melt tension, the present composition has the advantage of being able to provide extruded foams with a high expansion ratio.

[0051] ((Meth)acrylic Polymer) In this specification, the term "(meth)acrylic polymer" refers to a resin in which the content of (meth)acrylic units derived from (meth)acrylic monomers is the highest among all structural units constituting the resin. The (meth)acrylic polymer contains, for example, more than 50% by weight of (meth)acrylic units per 100% by weight of the polymer. The (meth)acrylic polymer preferably contains 60% by weight or more of (meth)acrylic units per 100% by weight of the polymer, preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more. The (meth)acrylic polymer may contain 100% by weight of (meth)acrylic units per 100% by weight of the polymer. In other words, the (meth)acrylic polymer may be composed solely of (meth)acrylic units.

[0052] The (meth)acrylic monomer is the same as that described above in the section (Copolymer (B)), and therefore the description therein is incorporated by reference and will not be repeated here. The (meth)acrylic monomer may be used alone or in combination of two or more.

[0053] (Copolymer Having Aromatic Vinyl Units and Unsaturated Nitrile Units as Structural Units) In this specification, the "copolymer having aromatic vinyl units and unsaturated nitrile units as structural units" in the processing aid (C) is also referred to as "copolymer (C)."

[0054] The copolymer (C) is not particularly limited, but examples thereof include copolymers containing aromatic vinyl units and unsaturated nitrile units in total in an amount of more than 50% by weight based on 100% by weight of the copolymer.

[0055] Examples of aromatic vinyl monomers from which the aromatic vinyl units are derived include (i) styrene, and (ii) styrene derivatives such as ethylstyrene, α-methylstyrene, p-methylstyrene, and halogenated styrenes (e.g., monobromostyrene, dibromostyrene, tribromostyrene, and chlorostyrene).The aromatic vinyl monomers may be used alone or in combination of two or more.

[0056] The unsaturated nitrile monomer from which the unsaturated nitrile unit is derived is the same as that described above in the section (Copolymer (B)), and therefore the description therein is incorporated by reference and will not be repeated here. The unsaturated nitrile monomer may be used alone or in combination of two or more.

[0057] The copolymer (C) may have a structural unit other than the aromatic vinyl unit and the unsaturated nitrile unit, for example, a structural unit that is copolymerizable with an aromatic vinyl-based monomer and / or an unsaturated nitrile-based monomer and that is derived from a monomer other than the aromatic vinyl-based monomer and the unsaturated nitrile-based monomer (hereinafter also referred to as "other monomer (C)").

[0058] Examples of the other monomer (C) include (meth)acrylic monomers and conjugated diene monomers. The (meth)acrylic monomers and conjugated diene monomers are the same as those described above in the section (Copolymer (B)), and therefore the description therefor is incorporated by reference and will not be repeated here. Only one type of the other monomer (C) may be used, or two or more types may be used in combination.

[0059] The content of aromatic vinyl units in copolymer (C) is not particularly limited, but is preferably 55 to 95% by weight, more preferably 60 to 90% by weight, even more preferably 65 to 85% by weight, and particularly preferably 70 to 80% by weight, based on 100% by weight of the copolymer. When the content of aromatic vinyl units in copolymer (C) is within the above range, the present composition has the advantage that it is easy to obtain extruded foam molded articles having a high expansion ratio and a high closed cell content.

[0060] The content of the unsaturated nitrile unit in copolymer (C) is not particularly limited, but is preferably 5 to 45% by weight, more preferably 10 to 40% by weight, even more preferably 15 to 35% by weight, and particularly preferably 20 to 30% by weight, based on 100% by weight of the copolymer. When the content of the unsaturated nitrile unit in copolymer (C) is within the above range, the present composition has the advantage that it is easy to obtain extruded foam molded articles having a high expansion ratio and a high closed cell content.

[0061] The total content of aromatic vinyl units and unsaturated nitrile units in copolymer (C) is not particularly limited, but is preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more, based on 100% by weight of the copolymer. The total content of aromatic vinyl units and unsaturated nitrile units in copolymer (C) may be 100% by weight. In other words, copolymer (C) may be composed only of aromatic vinyl units and unsaturated nitrile units.

[0062] The copolymer (C) is preferably a styrene / acrylonitrile copolymer containing styrene units and acrylonitrile units. The copolymer (C) may be used singly or in combination of two or more. The copolymer (C) preferably contains at least a styrene / acrylonitrile copolymer. When the copolymer (C) contains at least a styrene / acrylonitrile copolymer, the present composition has the advantage of increasing the expansion ratio and closed cell content of the resulting extruded foam.

[0063] From the viewpoint of improving the dispersibility of the processing aid (C) in the vinyl chloride resin (A) and the polymer (B) in the composition, the content of α-methylstyrene units in the (meth)acrylic polymer contained in the processing aid (C) is preferably less than 20% by weight, and more preferably 0% by weight (i.e., no α-methylstyrene units) per 100 weight of the (meth)acrylic polymer. From the same viewpoint, the content of α-methylstyrene units in the copolymer (C) contained in the processing aid (C) is preferably less than 20% by weight, and more preferably 0% by weight (i.e., no α-methylstyrene units) per 100 weight of the copolymer (C).

[0064] As the copolymer (C), commercially available products (for example, Blendex 869 manufactured by Galata) can also be used.

[0065] The weight-average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000. When the weight-average molecular weight of the processing aid (C) is (a) 1,500,000 or more, the present composition has the advantages of excellent cell retention during extrusion foam molding and of being able to obtain an appropriate melt viscosity during extrusion foam molding. When the weight-average molecular weight of the processing aid (C) is 8,000,000 or less, the present composition has the advantage of improving the dispersibility of the processing aid (C) in the vinyl chloride resin (A) and polymer (B) in the present composition. The weight average molecular weight of the processing aid (C) is preferably 2,000,000 to 7,500,000, more preferably 2,500,000 to 6,500,000, even more preferably 3,000,000 to 6,000,000, and particularly preferably 3,500,000 to 5,000,000.

[0066] The weight-average molecular weight of the processing aid (C) can be adjusted by the type and amount of radical polymerization initiator and the type and amount of chain transfer agent used in producing the processing aid (C), the internal temperature of the polymerization reactor, the amount of dissolved oxygen in the reaction system, the monomer concentration in the polymerization reactor, and the like.

[0067] The content of the processing aid (C) in the composition is 5.0 to 30.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B). When the content of the processing aid (C) per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) is 5.0 parts by weight or more, the composition has the advantage of excellent cell retention during extrusion foam molding. When the content of the processing aid (C) per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) is 30.0 parts by weight or less, the composition has the advantage of being able to achieve an appropriate melt viscosity during extrusion foam molding. The content of the processing aid (C) in the composition is more preferably 6.0 to 28.0 parts by weight, more preferably 7.0 to 26.0 parts by weight, even more preferably 8.0 to 24.0 parts by weight, and particularly preferably 9.0 to 22.0 parts by weight, per 100 parts by weight of the total of the vinyl chloride resin (A) and the copolymer (B).

[0068] The content of the processing aid (C) in the composition is preferably 3.0 to 25.0 parts by weight, more preferably 4.0 to 22.0 parts by weight, more preferably 5.0 to 20.0 parts by weight, even more preferably 6.0 to 18.0 parts by weight, and particularly preferably 7.0 to 16.0 parts by weight, per 100 parts by weight of the composition. When the content of the processing aid (C) per 100 parts by weight is 3.0 parts by weight or more, the composition has the advantage of excellent cell retention during extrusion foam molding. When the content of the processing aid (C) per 100 parts by weight is 25.0 parts by weight or less, the composition has the advantage of being able to obtain a melt viscosity suitable for extrusion foam molding.

[0069] In the present composition, the ratio of the content of copolymer (B) to the content of processing aid (C) (content of copolymer (B) / content of processing aid (C)) is not particularly limited. From the viewpoint of foaming properties, in the present composition, the ratio of the content of copolymer (B) to the content of processing aid (C) (content of copolymer (B) / content of processing aid (C)) is preferably greater than 0.5. In other words, in the present composition, the content of processing aid (C) is preferably less than the content of copolymer (B). In the present composition, the ratio of the content of copolymer (B) to the content of processing aid (C) (copolymer (B) content / processing aid (C) content) is preferably greater than 0.5 and less than 10.0, more preferably greater than 0.7 and less than 10.0, more preferably greater than 1.0 and less than 10.0, more preferably greater than 1.0 and less than 8.0, more preferably greater than 1.0 and less than 7.0, even more preferably 1.1 to 6.0, and particularly preferably 1.2 to 5.5. When the ratio of the content of copolymer (B) to the content of processing aid (C) (copolymer (B) content / processing aid (C) content) is greater than 0.5, the present composition has the advantage that it can be extruded and foamed at low temperatures. When the ratio of the content of copolymer (B) to the content of processing aid (C) is 10.0 or less, the present composition has the advantage that it can produce extruded foam molded articles with a high expansion ratio.

[0070] The method for producing the processing aid (C), in other words, the polymerization method for the processing aid (C), can be any known method and is not particularly limited. Examples of the polymerization method for the processing aid (C) include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, with emulsion polymerization being preferred. The method for producing the processing aid (C) (e.g., the emulsion polymerization method for the processing aid (C)) can be similar to the method described above (Production of Copolymer (B)), except for the monomer composition used.

[0071] When producing a processing aid (C) containing a (meth)acrylic polymer, the (meth)acrylic polymer may be produced together with a polymer other than the (meth)acrylic polymer to improve granulation properties during production. When producing a processing aid (C) containing a copolymer (C), the copolymer (C) may be produced together with a polymer other than the copolymer (C) to improve granulation properties during production. When producing a processing aid (C) containing a (meth)acrylic polymer and a copolymer (C), the (meth)acrylic polymer and the copolymer (C) may be produced together with a polymer other than the (meth)acrylic polymer and the copolymer (C) to improve granulation properties during production. In this specification, "a polymer other than a (meth)acrylic polymer that is produced together with a (meth)acrylic polymer in a processing aid (C) containing a (meth)acrylic polymer to improve the granulation ability of the (meth)acrylic polymer," "a polymer other than a (meth)acrylic polymer that is produced together with a copolymer (C) in a processing aid (C) containing a copolymer (C) to improve the granulation ability of the copolymer (C)," and "a polymer other than a (meth)acrylic polymer and a copolymer (C) that is produced together with a (meth)acrylic polymer and a copolymer (C) to improve the granulation ability of the (meth)acrylic polymer and a copolymer (C)" may be collectively referred to as "carrier (C)."

[0072] The carrier (C) is not particularly limited, but a (meth)acrylic polymer obtained by polymerizing a (meth)acrylic monomer is preferably used.

[0073] A case where a (meth)acrylic polymer is produced together with a carrier (C) (hereinafter also referred to as "Case C1") will be described. In Case C1, it is preferable to polymerize the carrier (C) in the presence of the (meth)acrylic polymer after polymerizing the (meth)acrylic polymer. In Case C1, when the (meth)acrylic polymer is obtained by, for example, emulsion polymerization, it is particularly preferable to produce (polymerize) the carrier (C) in a latex containing the (meth)acrylic polymer after producing (polymerizing) the (meth)acrylic polymer. When producing (polymerizing) the carrier (C) in a latex containing the (meth)acrylic polymer, a composite containing the (meth)acrylic polymer and the carrier (C) (or consisting of the (meth)acrylic polymer and the carrier (C)) can be obtained. In this composite, it is preferable that the carrier (C) is present outside the (meth)acrylic polymer and is present so as to cover at least a portion of the (meth)acrylic polymer. In this composite, the carrier (C) may cover the entire (meth)acrylic polymer or may be impregnated into the particulate (meth)acrylic polymer. In this composite, it is preferable that the (meth)acrylic polymer and the carrier (C) are not chemically bonded to each other. In Case C1, a composite containing a (meth)acrylic polymer and a carrier (C) (or consisting of a (meth)acrylic polymer and a carrier (C)) is considered to be the processing aid (C). That is, in Case C1, the weight-average molecular weight of the processing aid (C) can be said to be the weight-average molecular weight of the composite containing a (meth)acrylic polymer and a carrier (C) (or consisting of a (meth)acrylic polymer and a carrier (C)). Furthermore, in Case C1, the content of the processing aid (C) can be said to be the content of the composite containing a (meth)acrylic polymer and a carrier (C) (or consisting of a (meth)acrylic polymer and a carrier (C)).

[0074] A case where copolymer (C) is produced together with carrier (C) (hereinafter also referred to as "Case C2") will be described. In Case C2, it is preferable to polymerize copolymer (C) and then polymerize carrier (C) in the presence of copolymer (C). In Case C2, when copolymer (C) is obtained, for example, by emulsion polymerization, it is particularly preferable to produce (polymerize) carrier (C) in a latex containing copolymer (C) after the production (polymerization) of copolymer (C). When the production (polymerization) of carrier (C) is performed in a latex containing copolymer (C), a composite containing copolymer (C) and carrier (C) (or consisting of copolymer (C) and carrier (C)) can be obtained. In the composite, carrier (C) is preferably present outside copolymer (C) and present so as to cover at least a portion of copolymer (C). In the composite, carrier (C) may cover the entire copolymer (C) or may be impregnated inside particulate copolymer (C). In the composite, copolymer (C) and carrier (C) are preferably not chemically bonded to each other. In case C2, a composite containing copolymer (C) and carrier (C) (or consisting of copolymer (C) and carrier (C)) is considered to be processing aid (C). That is, in case C2, the weight average molecular weight of processing aid (C) can be said to be the weight average molecular weight of the composite containing copolymer (C) and carrier (C) (or consisting of copolymer (C) and carrier (C)). Also, in case C2, the content of processing aid (C) can be said to be the content of the composite containing copolymer (C) and carrier (C) (or consisting of copolymer (C) and carrier (C)).

[0075] A case where the (meth)acrylic polymer and copolymer (C) are produced together with the carrier (C) (hereinafter also referred to as "Case C3") will be described. In Case C3, it is preferable to polymerize the (meth)acrylic polymer and copolymer (C) and then polymerize the carrier (C) in the presence of the (meth)acrylic polymer and copolymer (C). In Case C3, when the (meth)acrylic polymer and copolymer (C) are obtained by, for example, emulsion polymerization, it is particularly preferable to produce (polymerize) the carrier (C) in a latex containing the (meth)acrylic polymer and copolymer (C) after the production (polymerization) of the (meth)acrylic polymer and copolymer (C). When the production (polymerization) of the carrier (C) is carried out in a latex containing the (meth)acrylic polymer and copolymer (C), a composite containing the (meth)acrylic polymer, copolymer (C), and carrier (C) (or consisting of the (meth)acrylic polymer, copolymer (C), and carrier (C)) can be obtained. In the composite, the carrier (C) is preferably present on the outside of the (meth)acrylic polymer and copolymer (C) and present so as to cover at least a portion of the (meth)acrylic polymer and copolymer (C). In the composite, the carrier (C) may cover the entire (meth)acrylic polymer and copolymer (C), or may be impregnated into the particulate (meth)acrylic polymer and copolymer (C). In the composite, the (meth)acrylic polymer and copolymer (C) and the carrier (C) are preferably not chemically bonded to each other. In Case C3, a composite containing a (meth)acrylic polymer, copolymer (C), and carrier (C) (or consisting of a (meth)acrylic polymer, copolymer (C), and carrier (C)) is considered to be the processing aid (C). That is, in Case C3, the weight average molecular weight of the processing aid (C) can be said to be the weight average molecular weight of the composite containing a (meth)acrylic polymer, copolymer (C), and carrier (C) (or consisting of a (meth)acrylic polymer, copolymer (C), and carrier (C)). In addition, in case C3, the content of the processing aid (C) can be said to be the content of the complex containing the (meth)acrylic polymer, the copolymer (C), and the carrier (C) (or consisting of the (meth)acrylic polymer, the copolymer (C), and the carrier (C)).

[0076] In cases C1 to C3, the composition may contain a carrier (C). Therefore, cases C1 to C3 can also be said to be cases in which the processing aid (C) contains a carrier (C).

[0077] (Blowing Agent (D)) The blowing agent (D) is not particularly limited. Examples of the blowing agent (D) include physical blowing agents and chemical blowing agents. Examples of physical blowing agents include (a) aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, and hexane; (b) alicyclic hydrocarbons such as cyclopentane and cyclobutane; (c) ethers such as dimethyl ether, diethyl ether, and methyl ethyl ether; (d) alcohols such as methanol and ethanol; (e) inorganic gases such as air, nitrogen, and carbon dioxide; and (f) water. Examples of chemical blowing agents include thermal decomposition type blowing agents. Examples of thermal decomposition type blowing agents include inorganic thermal decomposition type blowing agents and organic thermal decomposition type blowing agents. Examples of inorganic thermal decomposition type blowing agents include sodium bicarbonate (also known as baking soda), hydrogen carbonates, and carbonates. Examples of organic thermal decomposition type blowing agents include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (for example, DPT (N,N'-dinitropentamethylenetetramine)), and oxybisbenzenesulfonylhydrazide (for example, OBSH (4,4'-oxybisbenzenesulfonylhydrazide)).

[0078] As the blowing agent (D), one of the above-mentioned various substances may be used alone, or two or more of them may be used in combination.

[0079] When a physical foaming agent is used, various equipment may be required, such as equipment for impregnating the resin composition with the physical foaming agent and equipment for explosion prevention. Therefore, the foaming agent (D) preferably contains a chemical foaming agent, and more preferably is a chemical foaming agent (composed solely of a chemical foaming agent). The foaming agent (D) preferably (i) contains a thermally decomposable foaming agent, more preferably consists solely of a thermally decomposable foaming agent, and even more preferably (ii) consists solely of one or more compounds selected from the group consisting of sodium bicarbonate, bicarbonate, carbonate, ADCA, DPT, and OBSH. When the foaming agent (D) has the above-described configuration, the present composition has the advantage of reducing the cost associated with the production of extruded foam molded articles, since impregnation equipment and explosion prevention equipment are not required. The foaming agent (D) can also be used in combination with a foaming aid (e.g., a urea compound, a zinc compound, etc.) that adjusts the decomposition temperature of the foaming agent.

[0080] The content of the blowing agent (D) in the composition is not particularly limited. The content of the blowing agent (D) in the composition is preferably 1.0 to 20.0 parts by weight, more preferably 1.5 to 18.0 parts by weight, more preferably 2.0 to 16.0 parts by weight, even more preferably 2.5 to 14.0 parts by weight, and particularly preferably 3.0 to 12.0 parts by weight, per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B). When the content of the blowing agent (D) is 3.0 parts by weight or more per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the composition has the advantage of being able to produce extruded foams with a high expansion ratio. When the content of the blowing agent (D) is 20.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the composition has the advantage of being able to produce extruded foams with a high expansion ratio at low temperatures.

[0081] The content of the blowing agent (D) in the composition is preferably 0.8 to 15.0 parts by weight, more preferably 1.2 to 12.0 parts by weight, more preferably 1.5 to 10.0 parts by weight, even more preferably 2.0 to 9.0 parts by weight, and particularly preferably 2.5 to 8.0 parts by weight, per 100 parts by weight of the composition. When the content of the blowing agent (D) per 100 parts by weight is 1.0 part by weight or more, the composition has the advantage of being able to produce extruded foams with a high expansion ratio. When the content of the blowing agent (D) per 100 parts by weight is 15.0 parts by weight or less, the composition has the advantage of being able to produce extruded foams with a high expansion ratio by low-temperature molding.

[0082] Since impregnation equipment and explosion-proof equipment are not required, and thus the cost associated with producing extruded foam-molded articles is further reduced, the lower the content of the physical blowing agent in the blowing agent (D), the more preferable. The content of the physical blowing agent in the blowing agent (D) is preferably less than 5 parts by weight, more preferably less than 3 parts by weight, even more preferably less than 1 part by weight, and particularly preferably 0 part by weight, per 100 parts by weight of the blowing agent (D). In other words, it is particularly preferred that the blowing agent (D) does not contain a physical blowing agent.

[0083] (Flow improver (E)) The present composition may further contain a flow improver (E) in addition to the vinyl chloride resin (A), the copolymer (B), the processing aid (C) and the foaming agent (D).

[0084] The flowability improver (E) is not particularly limited as long as it is a substance other than the vinyl chloride resin (A), the copolymer (B), and the processing aid (C). The flowability improver (E) can have the function of improving the fluidity of the composition, particularly the fluidity during melt-kneading. The flowability improver (E) preferably contains at least a first polymer (e1). In order to improve granulation properties during production, the flowability improver (E) preferably contains a second polymer (e2) in addition to the first polymer (e1). Only one type of flowability improver (E) may be used, or two or more types may be used in combination.

[0085] (First Polymer (e1)) The first polymer (e1) preferably contains, relative to the entire first polymer (e1) being 100% by weight, (i) 50% by weight to 70% by weight of aromatic vinyl units derived from aromatic vinyl monomers, (ii) 5% by weight to 20% by weight of vinyl cyanide units derived from vinyl cyanide monomers, and (iii) 10% by weight to 45% by weight of structural units copolymerizable with aromatic vinyl monomers and / or vinyl cyanide monomers and derived from vinyl monomers other than aromatic vinyl monomers and vinyl cyanide monomers. In this specification, "vinyl monomers copolymerizable with aromatic vinyl monomers and / or vinyl cyanide monomers and other than aromatic vinyl monomers and vinyl cyanide monomers" may also be referred to as "other monomers (E1)."

[0086] The aromatic vinyl monomer is the same as that described above in the section (Processing aid (C)), and therefore that description is incorporated herein by reference and will not be further described here. Styrene is preferred as the aromatic vinyl monomer in the first polymer (e1). The aromatic vinyl monomer in the first polymer (e1) may be used alone or in combination of two or more.

[0087] Examples of vinyl cyanide compounds include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred. One of these compounds may be used alone, or two or more may be used in combination.

[0088] Examples of other monomers (E1) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexyl (meth)acrylate, Straight-chain alkyl (meth)acrylates having 1 to 20 carbon atoms, such as sadecyl (meth)acrylate; isopropyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isoundecyl (meth)acrylate, isododecyl (meth)acrylate, and isotridecyl (meth)acrylate. branched alkyl(meth)acrylates having 3 to 20 carbon atoms such as cyclopropyl(meth)acrylate, cyclobutyl(meth)acrylate, cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, cyclooctyl(meth)acrylate, and cyclodecyl(meth)acrylate; branched alkyl(meth)acrylates having 3 to 20 carbon atoms such as cyclopropyl(meth)acrylate, cyclobutyl(meth)acrylate, cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, cyclooctyl(meth)acrylate, and cyclodecyl(meth)acrylate; alkyl (meth)acrylates; aryl (meth)acrylates such as phenyl (meth)acrylate and methylphenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride, and citraconic anhydride; unsaturated acids such as acrylic acid and methacrylic acid; imide compounds of α,β-unsaturated dicarboxylic acids such as maleimide, N-methylmaleimide, N-butylmaleimide, N-(p-methylphenyl)maleimide, N-phenylmaleimide, and N-cyclohexylmaleimide;Examples of such unsaturated compounds include epoxy group-containing unsaturated compounds such as glycidyl (meth)acrylate and allyl glycidyl ether; unsaturated carboxylic acid amides such as acrylamide and methacrylamide; amino group-containing unsaturated compounds such as acrylamine, aminomethyl (meth)acrylate, aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and aminostyrene; hydroxyl group-containing unsaturated compounds such as 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, 3-hydroxy-2-methyl-1-propene, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and hydroxystyrene; and oxazoline group-containing unsaturated compounds such as vinyloxazoline. These may be used alone or in combination of two or more.

[0089] The content of α-methylstyrene units in the first polymer (e1) contained in the flow improver (E) may be less than 60% by weight, less than 55% by weight, less than 50% by weight, less than 45% by weight, less than 40% by weight, less than 35% by weight, less than 30% by weight, less than 25% by weight, or less than 20% by weight, based on 100 weight of the first polymer (e1).

[0090] The weight-average molecular weight of the first polymer (e1) is not particularly limited, but is preferably 15,000 to 120,000. When the weight-average molecular weight of the first polymer (e1) is 120,000 or less, a composition can be provided that has a good balance between the three properties of the fluidity and kneadability of the composition when melted, and the foamability of the extruded foam-molded product. When the weight-average molecular weight of the first polymer (e1) is 15,000 or more, there is no risk that the melting initiation temperature of the composition will be too low, resulting in the advantage of excellent handleability.

[0091] (Second polymer (e2)) In the flow improver (E), the second polymer (e2) is an optional component and may not be contained. When the flow improver (E) contains the second polymer (e2), it is preferable that the second polymer (e2) is produced together with the first polymer (e1). The case where the first polymer (e1) is produced together with the second polymer (e2) (hereinafter also referred to as "Case B") will be described. In Case B, it is preferable to polymerize the first polymer (e1) and then polymerize the second polymer (e2) in the presence of the first polymer (e1). In Case B, when the first polymer (e1) is obtained by, for example, emulsion polymerization, it is particularly preferable to produce (polymerize) the second polymer (e2) in a latex containing the first polymer (e1) after producing (polymerizing) the first polymer (e1). When the production (polymerization) of the second polymer (e2) is carried out in a latex containing the first polymer (e1), a composite containing the first polymer (e1) and the second polymer (e2) (or consisting of the first polymer (e1) and the second polymer (e2)) can be obtained. In the composite, the second polymer (e2) is preferably present on the outside of the first polymer (e1) and present so as to cover at least a portion of the first polymer (e1). In the composite, the second polymer (e2) may cover the entire first polymer (e1) or may be impregnated into the particulate first polymer (e1). In the composite, the first polymer (e1) and the second polymer (e2) are preferably not chemically bonded to each other. In Case B, the composite containing the first polymer (e1) and the second polymer (e2) (or consisting of the first polymer (e1) and the second polymer (e2)) is considered to be the flow improver (E). That is, in case B, the content of the flow improver (E) can be said to be the content of the complex containing the first polymer (e1) and the second polymer (e2) (or consisting of the first polymer (e1) and the second polymer (e2)).

[0092] When the flow improver (E) contains a second polymer (e2), the second polymer (e2) preferably contains, as constituent monomers, (i) 10% by weight to 90% by weight of alkyl methacrylate units derived from alkyl methacrylate, and (ii) 10% by weight to 90% by weight of structural units derived from a vinyl monomer other than alkyl methacrylate that is copolymerizable with alkyl methacrylate, based on the entire second polymer (e2) being 100% by weight. In this specification, the "vinyl monomer other than alkyl methacrylate that is copolymerizable with alkyl methacrylate" may also be referred to as "other monomer (E2)."

[0093] When the content ratio of alkyl methacrylate units in the second polymer (e2) is relatively high, the Tg (glass transition temperature) of the second polymer (e2) can be increased, and as a result, the granulation property of the flowability improver (E) can be improved.

[0094] The alkyl methacrylate is the same as the alkyl (meth)acrylates described above in the section (Copolymer (B)), and therefore the description therein is incorporated by reference and will not be described here.

[0095] In the second polymer (e2), the number of carbon atoms in the alkyl group of the alkyl methacrylate is preferably 1 to 14, more preferably 1 to 12, even more preferably 1 to 10, still more preferably 1 to 8, and particularly preferably 1 to 6. The alkyl methacrylate in the second polymer (e2) is more preferably a linear alkyl methacrylate, and more preferably methyl methacrylate or ethyl methacrylate.

[0096] Examples of the other monomer (E2) in the second polymer (e2) include the various monomers described above in the section (First polymer (e1)), and therefore, the description therein is incorporated by reference and further description will be omitted here.

[0097] The content of α-methylstyrene units in the second polymer (e2) that can be contained in the flow improver (E) may be less than 60% by weight, less than 55% by weight, less than 50% by weight, less than 45% by weight, less than 40% by weight, less than 35% by weight, less than 30% by weight, less than 25% by weight, or less than 20% by weight, based on 100% by weight of the second polymer (e2).

[0098] It is preferable that the second polymer (e2) is present outside the first polymer (e1), and that the Tg of the second polymer (e2) is 30° C. to 110° C. According to this configuration, the granulation property of the flowability improver (E) can be improved.

[0099] The weight average molecular weight of the second polymer (e2) is not particularly limited, but is preferably from 20,000 to 300,000, and more preferably from 20,000 to 150,000.

[0100] When the flowability improver (E) contains the second polymer (e2), from the viewpoint of the balance between the three factors of the flowability of the composition when melted, the impact resistance of the extruded foam molded product, and the heat resistance of the extruded foam molded product, it is preferred that the flowability improver (E) contains 60% by weight to 90% by weight of the first polymer (e1) and 10% by weight to 40% by weight of the second polymer (e2), with the total of the first polymer (e1) and the second polymer (e2) being 100% by weight.

[0101] The content of the flowability improver (E) in the composition is not particularly limited. The content of the flowability improver (E) in the composition is preferably 0.1 to 12.0 parts by weight, more preferably 0.3 to 10.0 parts by weight, more preferably 0.5 to 8.0 parts by weight, more preferably 0.7 to 6.0 parts by weight, even more preferably 0.8 to 5.0 parts by weight, and particularly preferably 1.0 to 4.0 parts by weight, per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B). When the content of the flowability improver (E) is 0.1 parts by weight or more per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the composition has the advantage of an earlier gel point when melted and improved kneadability. When the content of the flowability improver (E) is 12.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the composition has the advantage of improved fluidity when melted.

[0102] The content of the flow improver (E) in the composition is preferably 0.1 to 10.0 parts by weight, more preferably 0.3 to 8.0 parts by weight, more preferably 0.4 to 7.0 parts by weight, more preferably 0.6 to 5.0 parts by weight, even more preferably 0.7 to 4.0 parts by weight, and particularly preferably 0.8 to 3.0 parts by weight, per 100 parts by weight of the composition. When the content of the processing aid (C) per 100 parts by weight of the composition is 0.1 parts by weight or more, the composition has the advantage of having an earlier gel point when melted and improved kneadability. When the content of the flow improver (E) per 100 parts by weight of the composition is 10.0 parts by weight or less, the composition has the advantage of improved fluidity when melted.

[0103] The method for producing flowability improver (E), in other words, the polymerization method of flowability improver (E), can use known methods, and is not particularly limited.As the polymerization method of flowability improver (E), for example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. can be adopted, but it is preferable to adopt emulsion polymerization.As the method for producing flowability improver (E) (for example, the emulsion polymerization method of flowability improver (E)), except for the different monomer composition used, the description in the above-mentioned section (the method for producing copolymer (B)) can be appropriately used.

[0104] (Other additives) In addition to the vinyl chloride resin (A), copolymer (B), processing aid (C) and foaming agent (D), and optionally containing flowability improver (E), the present composition may further contain other additives as needed.Other additives are not particularly limited, but include resins other than vinyl chloride resin (A), flame retardants, stabilizers, processing aids other than processing aid (C) (other processing aids), lubricants, flowability improvers other than flowability improver (E), impact strength improvers, nucleating agents, foaming aids, antistatic agents, radiation heat transfer inhibitors, plasticizers, solvents, colorants, fillers, etc.These other additives may be used alone or in combination of two or more.

[0105] Examples of processing aids other than processing aid (C) include (a) (meth)acrylic polymers having a weight-average molecular weight of less than 1,500,000 or more than 8,000,000, and (b) copolymers having aromatic vinyl units and unsaturated nitrile units as structural units, and having a weight-average molecular weight of less than 1,500,000 or more than 8,000,000.

[0106] As the stabilizer, those conventionally used in vinyl chloride resins and chlorinated vinyl chloride resins can be used. Examples of stabilizers include (a) tin-based stabilizers, (b) lead-based stabilizers, (c) calcium-zinc-based stabilizers, (d) barium-zinc-based stabilizers, (e) antioxidants such as phenolic compounds, phosphorus-based compounds, and amine-based compounds, (f) epoxy-based stabilizers, and (g) zeolites. As the stabilizer, octyltin mercapto, a tin-based stabilizer, is preferably used. As the octyltin mercapto, commercially available products (e.g., TVS #8831 manufactured by Nitto Kasei Kogyo Co., Ltd.) may be used.

[0107] Examples of lubricants include (a) waxes such as ester wax and polyethylene wax, (b) low-density polyethylene, (c) fatty acid esters, and (d) fatty acid metal salts such as calcium stearate and zinc stearate. Low-density polyethylene and fatty acid esters are preferably used as lubricants. Commercially available low-density polyethylenes (e.g., AC-629A manufactured by Honewell) may also be used. Commercially available lubricants (e.g., SL-02 manufactured by Riken Vitamin Co., Ltd. and Loxiol G32 manufactured by EMERY OLEOCHEMICALS) may also be used.

[0108] (Method for Producing Vinyl Chloride Resin Composition) The method for producing the present composition is not particularly limited. For example, the present composition can be produced (obtained) by mixing the respective raw materials ((a) vinyl chloride resin (A), copolymer (B), processing aid (C), foaming agent (D), and optionally, flow improver (E) and other additives).

[0109] The device used for mixing the raw materials is not particularly limited, and a mixer (e.g., a Henschel mixer, a tumbler mixer, a super mixer, etc.) can be used. The temperature (mixing temperature) used for mixing the raw materials is not particularly limited, and can be, for example, 90°C to 120°C.

[0110] [2. Extruded foam molded product] An extruded foam molded product according to one embodiment of the present invention is an extruded foam molded product obtained by extrusion foaming a vinyl chloride resin composition for extruded foam molded products according to one embodiment of the present invention, as described in the section [1. Vinyl chloride resin composition]. It can also be said that an extruded foam molded product according to one embodiment of the present invention comprises a vinyl chloride resin composition for extruded foam molded products according to one embodiment of the present invention, as described in the section [1. Vinyl chloride resin composition].

[0111] The extruded foam molded product has the above-described structure and has the advantage of a high expansion ratio. The higher the expansion ratio, the lighter the extruded foam molded product is compared to other extruded foam molded products of the same volume.

[0112] (Method for Producing Extruded Foam Molded Articles) The method for producing the extruded foam molded article, in other words, the method for extrusion foam molding of the composition, is not particularly limited, and known extrusion foam molding methods can be used. For example, the extruded foam molded article can be produced (obtained) by melt-kneading the composition using an extruder equipped with a die and extruding it through the die. Alternatively, the raw materials for the composition ((a) vinyl chloride resin (A), copolymer (B), processing aid (C), blowing agent (D), and optional flow improver (E) and other additives, etc.) are supplied to an extruder equipped with a die and melt-kneaded to produce the composition in the extruder, and the melt-kneaded composition can be extruded through the die to produce the extruded foam molded article.

[0113] The extruder is not particularly limited, and a single-screw extruder, a twin-screw extruder, etc. The temperature at which the composition is melt-kneaded (also referred to as the temperature of the composition, the mixing temperature, or the resin temperature) is not particularly limited, and may be, for example, 165°C to 200°C.

[0114] [3. Uses] The present composition and the present extruded foam molded article obtained by extrusion foam molding of the present composition can be suitably used particularly for building insulation materials, interior building materials, bathroom components, ceiling materials, extruded rigid plastic sandwich core materials, internal insulation core materials for resin sashes, core materials for metal sandwich panels, buffer materials, bathroom insulation materials, and hot water storage tank insulation materials. One embodiment of the present invention encompasses the inventions described in [1] to [6] below. [1] A composition comprising: a vinyl chloride resin (A); a copolymer (B); a processing aid (C); and a foaming agent (D), wherein the copolymer (B) contains 20 to 85% by weight of α-methylstyrene units as structural units in 100% by weight of the copolymer (B) and has a glass transition temperature of 90°C or higher, the content of the copolymer (B) is 5.0 to 75.0 parts by weight per 100 parts by weight of the total of the vinyl chloride resin (A) and the copolymer (B), the processing aid (C) comprises (i) a (meth)acrylic polymer and / or (ii) a copolymer having structural units of aromatic vinyl units and unsaturated nitrile units, and the weight average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000,

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[0100] [4] The vinyl chloride resin composition for extrusion foam molding according to any one of [1] to [3], wherein the foaming agent (D) is a chemical foaming agent.[5] The vinyl chloride resin composition for extrusion foam moldings according to any one of [1] to [4], wherein the vinyl chloride resin (A) comprises a chlorinated vinyl chloride resin. [6] An extrusion foam molding obtained by extrusion foaming the vinyl chloride resin composition for extrusion foam moldings according to any one of [1] to [5].

[0115] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. One embodiment of the present invention can be carried out by appropriately modifying the following examples within the scope that can comply with the above-mentioned and below-mentioned aims. All embodiments carried out by appropriately modifying the following examples are included within the technical scope of the present invention. In the following examples, comparative examples, and tables, "parts" and "%" mean parts by weight and % by weight, respectively.

[0116] [Measurement Methods] The methods for measuring and evaluating the various physical properties measured in the examples are shown below.

[0117] <Weight-Average Molecular Weight of Polymer, Copolymer, or Composite> The polymer, copolymer, or composite to be measured was dissolved in tetrahydrofuran (THF) to obtain a THF-soluble fraction. The weight-average molecular weight was determined using gel permeation chromatography (HLC-8220GPC, manufactured by Tosoh Corporation) with the THF-soluble fraction as a sample. The measurement conditions were: sample solution: 20 mg sample / 10 mL THF, measurement temperature: 25°C, detector: differential refractometer, injection volume: 1 mL. Separately, polystyrene with a known weight-average molecular weight was subjected to gel permeation chromatography under the same conditions as the sample, and a calibration curve was prepared. Using the obtained calibration curve, the weight-average molecular weight of the polymer, copolymer, or composite was calculated in terms of polystyrene.

[0118] <Glass transition temperature (Tg) of (co)polymer> The Tg of a polymer or copolymer was calculated using the above-mentioned FOX equation. The Tg of homopolymers is as follows: α-methylstyrene (168°C), acrylonitrile (97°C), methyl methacrylate (110°C), and butyl acrylate (-54°C).

[0119] <Extrusion Molding Evaluation> Using a Toyo Seiki Laboplast twin-screw conical extruder, and further using a breaker plate, two screen meshes #60, and a flat die having a thickness of 3 mm and a width of 11 mm, the compositions obtained in each Example and Comparative Example were extrusion-foamed to obtain extruded foam molded articles. The extrusion foam molding conditions were as follows: cylinder temperature: C1 / 170°C, C2 / 180°C, C3 / 180°C, D / 160°C, shaft rotation speed: 30 rpm, resin temperature: about 190°C.

[0120] The resulting extruded foam was measured for expansion ratio, and the moldability and appearance were confirmed.

[0121] (Expansion Ratio) The expansion ratio of the extruded foam molded product was measured using a specific gravity measuring instrument.

[0122] (Evaluation of moldability and appearance) The surface of the extruded foam molded article was visually inspected for the presence or absence of broken foam cells and the presence or absence of irregularities due to the broken cells, and rated based on the following criteria: 2 (very excellent): No broken foam cells were observed, and the surface was smooth with no irregularities. 1 (good): No broken foam cells were observed, but the surface was uneven with a difference in height that would not cause any problems in use. 0 (poor): Many broken cells were observed, and the broken cells caused many irregularities on the surface with a difference in height that would cause problems in use, making it rough.

[0123] [Materials] The materials used in the examples and comparative examples are shown below.

[0124] <Vinyl chloride resins (A)> A1: vinyl chloride resin (PVC) (manufactured by Kaneka Corporation, S-1007, degree of polymerization 700, vinyl chloride homopolymer) A2: chlorinated vinyl chloride resin (CPVC) (manufactured by Kaneka Corporation, H716S, degree of polymerization 600, chlorine content 67% by weight, resin obtained by chlorinating vinyl chloride homopolymer) <Copolymer (B)> B1: A composite containing copolymer (B) obtained in Production Example 1 below was used. The proportion of copolymer (B) in 100% by weight of the composite was 90% by weight.

[0125] <Processing Aids (C)> C1: Processing aid (C1) obtained in Production Example 2 below. C2: Processing aid (C2) obtained in Production Example 3 below. C3: Styrene / acrylonitrile copolymer (BLENDEX 869, SAN processing aid, manufactured by Galata Chemicals, weight average molecular weight (Mw) approximately 3 million). <Blowing Agents (D)> D1: Sodium bicarbonate (SC-P, manufactured by Eiwa Kasei Co., Ltd.). D2: Mixture of ADCA (azodicarbonamide) and sodium bicarbonate (FE-512, manufactured by Eiwa Kasei Co., Ltd.). <Flow Improver (E)> E1: Flow Improver (E1) obtained in Production Example 4 below. <Other Additives> (Other Processing Aids) F1: Other processing aid (F) obtained in Production Example 5 below. (Stabilizer) F2: Octyltin mercapto (TVS, manufactured by Nitto Kasei Co., Ltd.). #8831) (lubricant) F3: Special fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) F4: Fatty acid ester (manufactured by EMERY OLEOCHEMICALS, Loxiol G32) F5: Low-density polyethylene (manufactured by Honewell, AC-629A, oxidized type) [Production Examples] <Production Example 1> (Production of a composite containing copolymer (B)) 3.0 parts of sodium palmitate, 0.01 parts of ethylenediaminetetraacetic acid disodium salt, and 0.0025 parts of ferrous sulfate were dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and water was further added to make the total amount of the aqueous solution 250 parts.

[0126] The gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Then, while stirring the contents (aqueous solution), 0.4 parts of sodium formaldehyde sulfoxylate was added to a reactor equipped with a stirrer, and the contents were heated to 60°C. Then, 63 parts of α-methylstyrene, 27 parts of acrylonitrile, 0.27 parts of tertiary dodecyl mercaptan, and 0.27 parts of cumene hydroperoxide were continuously added dropwise to the contents over 6 hours. After the dropwise addition, the contents were stirred for 1 hour while maintaining the temperature of the contents at 60°C. Through the above operations, copolymer (B) was formed.

[0127] After the polymerization of copolymer (B) was completed, a mixture of 7.0 parts of methyl methacrylate, 3.0 parts of butyl acrylate, and 0.3 parts of t-butyl hydroperoxide was continuously added to the contents over 60 minutes while stirring the contents, and polymerization was carried out. After the addition of the mixture was completed, the contents were kept at a temperature of 60°C and the contents were stirred for at least 1 hour, thereby completing the polymerization. This operation formed a carrier (B) capable of coating at least a portion of copolymer (B). The contents were then cooled, and a latex of a composite containing copolymer (B) and carrier (B) was obtained.

[0128] Next, the resulting composite latex was added to 5 parts of a calcium chloride aqueous solution diluted to a concentration of 1% by weight at 65°C to coagulate the composite. The composite was then heat-treated, dehydrated, washed, and dried to obtain a composite powder. The glass transition temperature of copolymer (B) was calculated using the method described above, and Tg was found to be 130°C. The weight-average molecular weight of the composite was measured using the method described above, and was found to be 100,000.

[0129] <Production Example 2> (Production of Processing Aid (C1)) 0.5 parts of sodium dioctyl succinate was dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 140 parts.

[0130] The contents were heated to 60°C, and the gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Then, 0.0005 parts by weight of potassium persulfate was added to the contents. Next, the contents (aqueous solution) were stirred, and a mixture consisting of 72 parts of methyl methacrylate and 8 parts of butyl acrylate was added to the contents over 30 minutes. After the addition of the mixture, the contents were stirred for 5 hours while maintaining the temperature of the contents at 60°C to complete the polymerization reaction. Through the above operations, a (meth)acrylic polymer was formed.

[0131] After the polymerization of the (meth)acrylic polymer was completed, 0.05 parts by weight of potassium persulfate was added to the contents. Then, while stirring the contents, a mixture of 8 parts methyl methacrylate and 12 parts butyl acrylate was continuously added to the contents over 50 minutes to carry out polymerization. After the addition of the mixture was completed, the contents were kept at a temperature of 60°C and the contents were stirred for at least 1 hour to complete the polymerization. This procedure resulted in the formation of a carrier (C) capable of coating at least a portion of the (meth)acrylic polymer. The contents were then cooled to obtain a composite containing the (meth)acrylic polymer and the carrier (C), i.e., a latex of the processing aid (C1).

[0132] Next, a powder of the composite (i.e., processing aid (C1)) was obtained from the latex of the composite (i.e., processing aid (C1)) by the same method (operation) as in Production Example 1. The weight-average molecular weight of the composite (i.e., processing aid (C1)) was measured by the method described above, and was found to be 4,500,000.

[0133] <Production Example 3> (Production of Processing Aid (C2)) A (meth)acrylic polymer was formed in the same manner (operation) as in Production Example 2, except that the amount of potassium persulfate used was changed from 0.0005 parts by weight to 0.0002 parts by weight.

[0134] Next, a carrier (C) capable of coating at least a portion of the (meth)acrylic polymer was formed by the same method (operation) as in Production Example 2. Thereafter, the contents were cooled to obtain a composite containing the (meth)acrylic polymer and the carrier (C), i.e., a latex of processing aid (C2).

[0135] Next, a powder of the composite (i.e., processing aid (C2)) was obtained from the latex of the composite (i.e., processing aid (C2)) by the same method (operation) as in Production Example 1. The weight-average molecular weight of the composite (i.e., processing aid (C2)) was measured by the method described above and was found to be 6,000,000.

[0136] <Production Example 4> (Production of Flowability Improver (E1)) 1.0 part of dioctyl sodium sulfosuccinate, 0.0050 parts of ethylenediaminetetraacetic acid disodium salt, and 0.0025 parts of ferrous sulfate were dissolved in water to prepare an aqueous solution. The obtained aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 200 parts.

[0137] The gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Thereafter, while stirring the contents (aqueous solution), 0.4 parts of sodium formaldehyde sulfoxylate was placed in a reactor equipped with a stirrer, and the contents were heated to 75°C. Thereafter, while continuing to stir the contents, a mixture of 12.6 parts of acrylonitrile, 43.4 parts of styrene, 6.0 parts of butyl acrylate, 18.0 parts of methyl methacrylate, 0.8 parts of t-dodecyl mercaptan, and 1 part of t-butyl hydroperoxide was continuously added to the contents over 200 minutes, thereby carrying out polymerization. During the polymerization, 0.3 parts of dioctyl sodium sulfosuccinate was added to the contents twice at predetermined times. During the polymerization, 0.15 parts of sodium formaldehyde sulfoxylate was added to the contents once at predetermined times. A first polymer (e1-1) was formed by the above operations.

[0138] After the polymerization of the first polymer (e1-1) was completed, a mixture of 4 parts of butyl acrylate, 16 parts of methyl methacrylate, and 0.3 parts of t-butyl hydroperoxide was continuously added to the contents over 50 minutes while stirring the contents, and polymerization was carried out. After the addition of the mixture was completed, 0.2 parts of sodium formaldehyde sulfoxylate was added to the contents. Thereafter, the temperature of the contents was maintained at 75°C, and the contents were stirred for 1 hour or more, thereby completing the polymerization. By the above operation, a second polymer (e1-2) capable of coating at least a portion of the first polymer (e1-1) was formed. Thereafter, the contents were cooled, and a composite containing the first polymer (e1-1) and the second polymer (e1-2), i.e., a latex of flow improver (E1), was obtained.

[0139] Next, a powder of the composite (i.e., flowability improver (E1)) was obtained from the latex of the composite (i.e., flowability improver (E1)) by the same method (operation) as in Production Example 1. The weight-average molecular weight of the composite (i.e., flowability improver (E1)) was measured by the method described above, and was found to be 40,000.

[0140] <Production Example 5> (Production of other processing aid (F)) 0.5 parts of sodium dioctyl succinate, 0.0032 parts of ethylenediaminetetraacetic acid disodium salt, and 0.0008 parts of ferrous sulfate were dissolved in water to prepare an aqueous solution. The resulting aqueous solution was placed in a reactor equipped with a stirrer, and further water was added to make the total amount of the aqueous solution 200 parts.

[0141] The gas in the reactor was replaced with nitrogen to remove oxygen from the space and the aqueous solution. Thereafter, while stirring the contents (aqueous solution), 0.06 parts of sodium formaldehyde sulfoxylate was placed in a reactor equipped with a stirrer, and the contents were heated to 60°C. Thereafter, while continuing to stir the contents, a mixture of 80 parts of methyl methacrylate and 0.05 parts of t-butyl hydroperoxide was continuously added to the contents over 200 minutes, thereby carrying out polymerization. During the polymerization, 0.3 parts of dioctyl sodium sulfosuccinate was added to the contents twice at predetermined times. Through the above operations, a first polymer (f1) was formed.

[0142] After the polymerization of the first polymer (f1) was completed, a mixture of 8 parts methyl methacrylate, 12 parts butyl acrylate, and 0.05 parts t-butyl hydroperoxide was continuously added to the contents over 50 minutes while stirring the contents, and polymerization was carried out. After the addition of the mixture was completed, the contents were stirred for at least 1 hour while maintaining the temperature of the contents at 60°C, and the polymerization was completed. This operation formed a second polymer (f2) capable of coating at least a portion of the first polymer (f1). The contents were then cooled to obtain a composite containing the first polymer (f1) and the second polymer (f2), i.e., a latex of the other processing aid (F), which is a processing aid other than the processing aid (C).

[0143] Next, the latex of the obtained composite (i.e., other processing aid (F)) was added to 5 parts of a calcium chloride aqueous solution diluted to a concentration of 1% by weight at 45°C to coagulate the composite (i.e., other processing aid (F)). This was followed by heat treatment, dehydration, washing, and drying to obtain a powder of the composite (i.e., other processing aid (F)). The weight-average molecular weight of the composite (i.e., other processing aid (F)) was measured by the method described above and found to be 750,000.

[0144] Examples 1 to 13 and Comparative Examples 1 to 3 According to the formulations shown in Table 1, the raw materials were mixed at 100° C. in a Kawata Super Mixer to obtain vinyl chloride resin compositions.

[0145] Using the obtained vinyl chloride resin composition, an extruded foam was produced in accordance with the description in the above section <Extrusion molding evaluation>. The extruded foam was evaluated for expansion ratio, moldability, and appearance. The results are shown in Table 1.

[0146]

[0147] A comparison is made between Example 1 and Comparative Example 2. The extruded foam molded product of Example 1 has a high expansion ratio, indicating that the composition of Example 1 has excellent foamability. On the other hand, the extruded foam molded product of Comparative Example 2, which does not contain the processing aid (C), has a low expansion ratio, indicating that the composition of Comparative Example 2 has poor foamability.

[0148] Example 1 is compared with Comparative Example 3. The composition of Comparative Example 3 contains a processing aid with a molecular weight of 1,000,000 other than the processing aid (C). As a result, it is found that the extruded foam of Comparative Example 3 has an inferior expansion ratio.

[0149] The processing aid (C) may be used alone or in combination of two or more. In fact, two types of processing aid (C) were used in combination in Example 8. In Example 8, the extruded foam molding had a high expansion ratio, indicating that the composition had excellent foamability.

[0150] Example 7 and Example 9 are compared. The compositions of Example 7 and Example 9 have the same composition, except that the composition of Example 7 does not contain flow improver (E), while the composition of Example 9 contains flow improver (E). Compared with Example 7, Example 9 has a higher expansion ratio and is superior in moldability and appearance.

[0151] As the vinyl chloride resin (A), a combination of vinyl chloride resin and chlorinated vinyl chloride resin can also be used. In fact, the composition of Example 13 contains a vinyl chloride resin and a chlorinated vinyl chloride resin as the vinyl chloride resin (A). In Example 13, the expansion ratio of the extruded foam molding was high, indicating that the composition had excellent foamability.

[0152] According to one embodiment of the present invention, a vinyl chloride resin composition capable of producing an extruded foam with a high expansion ratio can be provided, and therefore, this embodiment of the present invention is particularly suitable for use in interior building materials, bathroom components, ceiling materials, extruded rigid plastic sandwich core materials, internal insulation core materials for resin sashes, core materials for metal sandwich panels, cushioning materials, bathroom insulation materials, and hot water tank insulation materials.

Claims

1. A composition comprising a vinyl chloride resin (A), a copolymer (B), a processing aid (C), and a foaming agent (D), wherein the copolymer (B) contains 20 to 85% by weight of α-methylstyrene units as structural units in 100% by weight of the copolymer (B) and has a glass transition temperature of 90°C or higher, the content of the copolymer (B) is 5.0 to 75.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B), the processing aid (C) comprises (i) a (meth)acrylic polymer and / or (ii) a copolymer having structural units consisting of aromatic vinyl units and unsaturated nitrile units, and the weight average molecular weight of the processing aid (C) is 1,500,000 to 8,000,000, a content of the processing aid (C) being 5.0 parts by weight to 30.0 parts by weight per 100 parts by weight of the vinyl chloride resin (A) and the copolymer (B) combined; 2. The vinyl chloride resin composition for extrusion foam moldings according to claim 1, wherein the vinyl chloride resin (A) has an average degree of polymerization of 400 to 1,300.

3. The vinyl chloride resin composition for extruded foam moldings according to claim 1, wherein, when the vinyl chloride resin composition further contains a carrier (B), the weight average molecular weight of the composite (B) containing the copolymer (B) and the carrier (B) is 20,000 to 800,000; and when the vinyl chloride resin composition does not contain a carrier (B), the weight average molecular weight of the copolymer (B) is 20,000 to 800,000.

4. The vinyl chloride resin composition for extrusion foam moldings according to claim 1, wherein the foaming agent (D) is a chemical foaming agent.

5. The vinyl chloride resin composition for extrusion foam molding according to claim 1, wherein the vinyl chloride resin (A) comprises a chlorinated vinyl chloride resin.

6. An extruded foam molded product obtained by extruding and foaming the vinyl chloride resin composition for extruded foam molded products according to any one of claims 1 to 5.

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