Resin composition for joint with ribs for sewage pipe and joint with ribs

Abstract

To provide a resin composition having small loads on working environment.SOLUTION: A resin composition for a joint with ribs for a sewage pipe contains a vinyl chloride-based resin, and a calcium zinc-based stabilizer. The calcium zinc-based stabilizer contains a zeolite-based stabilizer, and a degree of polymerization of the vinyl chloride-based resin is 670 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition for rib joints and rib joints.

Background Art

[0002] Vinyl chloride resins are materials with a wide range of applications. However, when exposed to heat or light, they cause appearance defects such as decomposition and discoloration. To prevent such appearance defects, various stabilizers are added to vinyl chloride resins. For example, Patent Document 1 discloses a vinyl chloride resin containing a tin-based stabilizer composed of a dialkyltin compound and a monoalkyltin compound. Patent Document 2 discloses a vinyl chloride resin for paste containing a calcium-zinc-based stabilizer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, vinyl chloride resins using tin-based compounds as stabilizers as in Patent Document 1 had a large burden on the working environment, such as regulations regarding the handling of dangerous substances and odor countermeasures. Further, what Patent Document 2 discloses is a resin composition for paste, and there is no description about using the resin composition for rib joints.

[0005] One aspect of the present invention aims to provide a resin composition for rib joints with a small burden on the working environment.

Means for Solving the Problems

[0006] The present invention includes the following aspects. <1> A polyvinyl chloride resin, A calcium-zinc stabilizer; A resin composition for rib joints comprising: <2> The calcium-zinc stabilizer includes a calcium salt of a fatty acid and a zinc salt of a fatty acid. <1> The resin composition for rib joints according to claim 1. <3> The degree of polymerization of the vinyl chloride resin is 670 or less. <1> or <2> The resin composition for rib joints according to claim 1. <4> Molded by injection molding, <1> ~ <3> 3. The resin composition for a rib joint according to claim 1 . <5> <1> ~ <4> A rib joint comprising the resin composition for rib joints according to any one of claims 1 to 5.

[0007] The present invention further includes the following aspects. <1> It contains polyvinyl chloride resin and calcium-zinc stabilizer. Does not contain β-diketones A resin composition for a ribbed joint for a sewer pipe, comprising: The vinyl chloride resin has a degree of polymerization of 670 or less. <2> The calcium-zinc stabilizer includes a calcium salt of a fatty acid and a zinc salt of a fatty acid. <1> The resin composition according to claim 1. <3> Molded by injection molding, <1> or <2> The resin composition according to claim 1. <4> <1> ~ <3> A ribbed joint comprising the resin composition according to any one of claims 1 to 5. Effect of the Invention

[0008] According to one aspect of the present invention, there is provided a resin composition for a rib joint that imposes a small burden on the working environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and various modifications are possible within the described scope. For example, embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Unless otherwise specified in this specification, "A~B" representing a numerical range is intended to mean "A or more and B or less".

[0010] [1. Resin composition for rib joint] The resin composition for rib joint according to one aspect of the present invention contains a vinyl chloride-based resin and a calcium-zinc-based stabilizer. Hereinafter, each component will be described.

[0011] [1.1. Vinyl chloride-based resin] Vinyl chloride-based resins are used as materials for general pipe fittings and are excellent in versatility and economy. In this specification, the vinyl chloride-based resin is intended to mean a resin having a unit derived from vinyl chloride as a main component. In one embodiment, the proportion of the unit derived from vinyl chloride in the vinyl chloride-based resin molecules is 50% by weight or more, 70% by weight or more, or 90% by weight or more. Only one type of vinyl chloride-based resin may be used, or two or more types may be used.

[0012] Specific examples of the vinyl chloride-based resin include a homopolymer of vinyl chloride, a copolymer of vinyl chloride and other monomers, and a graft copolymer obtained by graft copolymerizing a vinyl chloride monomer onto a polymer. Also, polymers in which the vinyl chloride units contained in these polymers are chlorinated are also included in the examples of the vinyl chloride-based resin (such as chlorinated polyvinyl chloride).

[0013] Examples of monomers copolymerizable with vinyl chloride include α-olefins (ethylene, propylene, butylene, etc.); vinyl esters (vinyl acetate, vinyl propionate, etc.); vinyl ethers (butyl vinyl ether, cetyl vinyl ether, etc.); methacrylic acid esters (methyl methacrylate, ethyl methacrylate, butyl acrylate, etc.); aromatic vinyls (styrene, α-methylstyrene, etc.); N-substituted maleimides (N-phenyl maleimide, N-cyclohexyl maleimide, etc.). The monomer copolymerizable with vinyl chloride may be only one type or two or more types.

[0014] Examples of polymers for graft copolymerizing vinyl chloride monomers include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. The polymer for graft copolymerizing vinyl chloride monomers may be only one type or two or more types.

[0015] The degree of polymerization of the vinyl chloride-based resin is preferably 670 or less, more preferably 660 or less. The lower limit of the degree of polymerization is preferably 600 or more, more preferably 620 or more. If the degree of polymerization is within the above range, the moldability of the resin composition is improved. Therefore, it is easy to prevent the occurrence of appearance defects in the product (such as yellowing of the molded body and incorporation of air bubbles).

[0016] The polymerization method of the vinyl chloride-based resin is not particularly limited. For example, a vinyl chloride-based resin obtained by emulsion polymerization, suspension polymerization, or bulk polymerization can be used.

[0017] [1.2. Calcium-Zinc Stabilizer] The resin composition for rib joints according to an embodiment of the present invention contains a calcium-zinc stabilizer. Since it is not necessary to use a tin stabilizer or a lead stabilizer, the burden on the working environment is small.

[0018] As the calcium-zinc stabilizer, known types of stabilizers can be used. Examples of the calcium-zinc stabilizer include organic stabilizers and inorganic stabilizers. Examples of the organic calcium-zinc stabilizer include metal soap stabilizers. Examples of the inorganic calcium-zinc stabilizer include zeolite stabilizers, layered metal hydroxide stabilizers, and other inorganic stabilizers. The calcium-zinc stabilizer may be used alone or in combination of two or more.

[0019] (Metal soap stabilizer) The metal soap stabilizer is a stabilizer containing a calcium salt of fatty acid and a zinc salt of fatty acid. The number of carbon atoms of the fatty acid is preferably 10 to 22, more preferably 12 to 20, and even more preferably 14 to 18. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid. Examples of the saturated fatty acid include capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, behenic acid, and montanic acid. Examples of the unsaturated fatty acid include linderic acid, tsuzuic acid, petroselinic acid, oleic acid, linoleic acid, linolenic acid, and arachidonic acid. The fatty acid may be a mixed fatty acid (such as beef tallow, coconut oil, palm oil, etc.). Among these, stearic acid, lauric acid, and palmitic acid are preferred, and stearic acid is more preferred.

[0020] (Zeolite stabilizer) Examples of zeolite-based stabilizers include natural or synthetic zeolites (such as A-type zeolite, X-type zeolite, Y-type zeolite, L-type zeolite, P-type zeolite, T-type zeolite, etc.). In addition to these, substances having a crystal structure such as offretite, erionite, mordenite, ferrierite, clinoptilolite, chabazite, analcite, and sodalite group aluminosilicates are also included. Further, substances obtained by subjecting the above-mentioned crystals to acid treatment and then ion-exchanging them with calcium ions or zinc ions are also included.

[0021] (Layered metal hydroxide-based stabilizer) Examples of layered metal hydroxide-based stabilizers include zinc-modified hydrotalcite-based stabilizers, calcium silicate, and mixtures thereof.

[0022] Examples of zinc-modified hydrotalcite-based stabilizers include composite metal hydroxides represented by the following general formula (1). M 2+ x M 3+ y (OH) 2x+3y-2z (A 2- ) z ·aH2O···(1) In formula (1), M 2+ is a divalent metal ion (such as Zn 2+ etc.). M 3+ is a trivalent metal ion (such as Al 3+ etc.). A 2- is a divalent anion (such as CO3 2- etc.). x, y, and z are positive numbers satisfying 8 ≧ x / y ≧ 1 / 4 and z / (x + y)> 1 / 20. a is a number satisfying 0.25 ≦ a / (x + y) ≦ 1.0.

[0023] Examples of calcium silicate include tobermorite and xonotlite. In particular, microcrystalline calcium silicate is preferred. Examples of microcrystalline calcium silicate include substances represented by the following general formula (2). CaO·xSiO2·nH2O···(2) In formula (2), x is a number from 0.5 to 2.0. n is a number of 2.5 or less.

[0024] Among the substances represented by formula (2), microcrystalline calcium silicate having X-ray diffraction images at an interplanar spacing of 3.01 to 3.08 Å, an interplanar spacing of 2.78 to 2.82 Å, and an interplanar spacing of 1.81 to 1.84 Å is preferable. Further, a composite of this microcrystalline calcium silicate and a polyhydric alcohol (or a partial ester of a polyhydric alcohol) is also preferable.

[0025] (Other inorganic stabilizers) Examples of other inorganic stabilizers include hydroxides of calcium and zinc, basic salts of calcium and zinc, and silicates of calcium and zinc. Examples of hydroxides of calcium and zinc include calcium hydroxide and zinc hydroxide. Examples of basic salts of calcium and zinc include substances represented by the following general formula (3) (calcium stearate carbonate, basic zinc carbonate, basic calcium stearate, basic zinc stearate, basic calcium palmitate, etc.). Examples of silicates of calcium and zinc include substances represented by the following general formula (4) (calcium silicate, zinc silicate, etc.). MO·qMX z / m ···(3) In formula (3), M is calcium or zinc. X is an inorganic acidic oxide anion or an organic anion. m is the valence of anion X. q is from 0.1 to 10, preferably from 0.5 to 5. Note that the general formula (3) is a formula expressed on an oxide basis. MO·kSiO2···(4) In formula (4), M is calcium or zinc. k is from 0.1 to 10, preferably from 0.5 to 5. Note that the general formula (4) is a formula expressed on an oxide basis.

[0026] The calcium-zinc stabilizer contained in the resin composition may contain a metal soap stabilizer as a main component. The proportion of the metal soap stabilizer in the total amount of the calcium-zinc stabilizer may be 50% by weight or more, 70% by weight or more, 90% by weight or more, or even 100% by weight.

[0027] The lower limit of the content of the calcium-zinc stabilizer contained in the resin composition is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, based on 100 parts by weight of the vinyl chloride resin. The upper limit of the content of the calcium-zinc stabilizer contained in the resin composition is preferably 8 parts by weight or less, more preferably 7 parts by weight or less, based on 100 parts by weight of the vinyl chloride resin. When the content is within the above range, the heat resistance and pulsating hydraulic pressure resistance of the resin composition are improved.

[0028] [1.3. Other Additives] The resin composition for a rib joint according to an embodiment of the present invention may contain other additives. Examples of other additives include co-stabilizers, fillers, pigments, lubricants, processing aids, light stabilizers, ultraviolet absorbers, and flame retardants. Each additive may be used alone or in combination of two or more.

[0029] Examples of the stabilizing agent include polyhydric alcohols, phenolic antioxidants, β-keto acid esters, and β-diketones. Specific examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, glycerin, diglycerin, dipentaerythritol, mannitol, sorbitol, trimethylolpropane, ditrimethylolpropane, tris isocyanurate, monopentaerythritol, and dipentaerythritol adipate. Examples of the phenolic antioxidants include bisphenol A, bisphenol B, bisphenol F, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, 1,6-hexamethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,6-hexamethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], bis[3,3-bis(4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxylbenzyl) isocyanurate, and triethylene glycol bis[(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate].Examples of β-keto acid esters and β-diketones include 1,3-cyclohexanedione, methylenebis-1,3-cyclohexanedione, 2-benzyl-1,3-cyclohexanedione, acetyltetralone, palmitoyltetralone, stearoyltetralone, benzoyltetralone, 2-acetylcyclohexanone, 2-benzoylcyclohexanone, 2-acetyl-1,3-cyclohexanedione, bis(benzoyl)methane, benzoyl-p-chlorobenzoylmethane, bis(4-methylbenzoyl)methane, bis(2-hydroxybenzoyl)methane, benzoylacetone, tribenzoylmethane, diacetylbenzoylmethane, stearoylbenzoylmethane, palmitoylbenzoylmethane, lauroylbenzoylmethane, dibenzoylmethane, bis(4-chlorobenzoyl)methane, bis(methylene-3,4-dioxybenzoyl)methane, benzoylacetylphenylmethane, stearoyl(4-methoxybenzoyl)methane, butanoylacetone, distearoylmethane, acetylacetone, stearoylacetone, bis(cyclohexanoyl)-methane, and dipivaloylmethane.

[0030] Examples of fillers include inorganic fillers. Examples of inorganic fillers include calcium carbonate, talc, clay, and silica.

[0031] Examples of pigments include organic pigments (such as azo pigments, phthalocyanine pigments, perylene pigments, and dye lake pigments); inorganic pigments (such as molybdate chromate pigments and ferrocyanide pigments).

[0032] Examples of lubricants include fatty acids (such as stearic acid); fatty acid esters (such as butyl stearate); olefin waxes (such as polyethylene and oxidized polyethylene); and hydrocarbon waxes (such as paraffin).

[0033] Examples of processing aids include homopolymers or copolymers of (meth)acrylate monomers (such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, etc.); copolymers of (meth)acrylate monomers and vinyl monomers (such as styrene, vinyltoluene, acrylonitrile, etc.).

[0034] Examples of light stabilizers include hindered amine light stabilizers.

[0035] Examples of ultraviolet absorbers include salicylic acid ester-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

[0036] Examples of flame retardants include halogen-based flame retardants; oxide or hydroxide-based flame retardants (oxides or hydroxides of antimony, zirconium, molybdenum, aluminum, silica, titanium, etc.).

[0037] The content of other additives is not particularly limited. In one embodiment, the content of the lubricant in the resin composition is 0.1 to 2.5% by weight. In one embodiment, the content of the filler or pigment in the resin composition is each 5.0% by weight or less.

[0038] In addition to the above-described additives, the resin composition may contain known additives (such as plasticizers). The content of this additive can be appropriately determined by those skilled in the art.

[0039] [1.4. Physical Properties of Resin Composition] The Vicat softening temperature of the resin composition is preferably 76°C or higher. The upper limit of the Vicat softening temperature can be, for example, 87°C or lower or 85°C or lower. Here, the Vicat softening temperature is measured based on JIS K 6816. If the Vicat softening temperature is within the above range, it can be said that it has sufficient heat resistance for producing rib joints.

[0040] The melting point of the resin composition is preferably 230°C or lower, more preferably 220°C or lower, and even more preferably 215°C or lower. If the melting point is within the above range, the moldability in injection molding or the like is enhanced.

[0041] The tensile yield strength of the resin composition is preferably 45 MPa or more, and more preferably 47 MPa or more. The upper limit of the tensile yield strength can be, for example, 59 MPa or lower or 57 MPa or lower. Here, the tensile yield strength is measured according to the measurement conditions of the tensile yield strength based on JIS K 6815 and JIS K 6743. If the tensile yield strength is within the above range, it can be said that it has the mechanical strength required for the rib joint.

[0042] [1.5. Method for Producing and Molding Resin Composition] The resin composition for rib joints according to one embodiment of the present invention can be produced by a method known in the art. For example, the resin composition can be produced by melt-kneading the above-described components using a melt-kneader (such as a single-screw extruder or a twin-screw extruder). The liquid component may be added during the melt-kneading using a liquid supply pump or the like.

[0043] The method for molding the resin composition is not particularly limited. A general method for molding a thermoplastic resin can be employed. Examples of such molding methods include injection molding, extrusion molding, vacuum molding, press molding, calender molding, and blow molding. Molding processing may be performed using a compound obtained by mixing each component as a material. After pelletizing the resin composition, molding processing may be performed using the obtained pellets as a material.

[0044] In one embodiment, the resin composition is molded by injection molding. Since the rib joint has a complex shape, molding by injection molding is suitable. A person skilled in the art can appropriately set the conditions for injection molding. When injection molding the resin composition, a generally commercially available injection molding machine can be used.

[0045] [2. Rib Joint] The rib joint according to one aspect of the present invention contains the above-described resin composition for rib joints. Since this rib joint contains the above-described resin composition for rib joints, the burden on the working environment is small.

[0046] The proportion of the resin composition for rib joints in the total weight of the rib joint is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more. In one embodiment, the rib joint consists only of the resin composition for rib joints.

[0047] The shape of the rib joint is not particularly limited. It may be a shape commonly adopted as a rib joint (such as a socket, an elbow, a cheese, etc.). Those skilled in the art can appropriately determine the thickness of the rib joint, the presence or absence of a socket, etc.

[0048] The rib joint can be used as a rib joint for water pipes (such as water supply pipes, sewer pipes, etc.), gas pipes, and other arbitrary pipes. Preferably, it is used as a rib joint for sewer pipes.

Examples

[0049] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0050] 〔Method of evaluation test〕 [1. Tensile yield strength] Test pieces were prepared from the fabricated rib joints, and the tensile yield strength was measured according to the test conditions for tensile yield strength based on JIS K 6815 and JIS K 6743. A screw-type uniaxial testing machine AGS-10kNX (Shimadzu Corporation) was used as the testing machine.

[0051] [2. Moldability] The appearance of the rib joints produced by injection molding was visually observed. The evaluation criteria are as follows. ○: There are no abnormalities such as bubbles or short shots in the appearance. △: There are almost no abnormalities such as bubbles or short shots in the appearance. ×: There are abnormalities such as bubbles or short shots in the appearance.

[0052] [Comparative Example 1] 100 parts by weight of polyvinyl chloride A (degree of polymerization: 700, TH-700, Taiyo Vinyl) and 5 to 6 parts by weight of a lead-based stabilizer (including tribasic lead sulfate, lead stearate, and other lubricants) were kneaded using a Henschel mixer. Using the obtained compound as a raw material, a T-shaped rib joint (diameter: 200 mm) was produced by injection molding. In the injection molding, the time from plasticizing the compound to weighing was 65 seconds, and the time for filling the molten resin into the mold was 77 seconds.

[0053] [Comparative Example 2] Polyvinyl chloride A was changed to polyvinyl chloride B (degree of polymerization: 650, S1006, manufactured by Kaneka), and a rib joint was produced in the same manner as in Comparative Example 1.

[0054] [Example 1] The lead-based stabilizer was changed to a calcium-zinc-based stabilizer (a mixture of calcium metal soap and zinc metal soap, Mizusawa Chemical), and a rib joint was produced in the same manner as in Comparative Example 1.

[0055] [Example 2] The lead-based stabilizer was changed to a calcium-zinc-based stabilizer (a mixture of calcium metal soap and zinc metal soap, Mizusawa Chemical), and a rib joint was produced in the same manner as in Comparative Example 2.

[0056] [Table 1]

[0057] The resin composition according to the example does not use a lead-based stabilizer and has less burden on the working environment. Also, the resin composition according to the example had a tensile yield strength equal to or higher than that of the resin composition according to the comparative example. Therefore, the resin composition according to the example has less burden on the working environment and has mechanical strength equal to or higher than that of conventional products.

[0058] In addition, the appearance of the rib joint of the resin composition according to Example 2 was superior to those of the resin compositions according to Example 1 and Comparative Example 1. From this, it can be said that by using a calcium-zinc-based stabilizer and reducing the degree of polymerization of polyvinyl chloride to a certain extent (for example, to 670 or less), the moldability is improved and a product with excellent appearance can be obtained.

Industrial Applicability

[0059] The resin composition of the present invention can be suitably used, for example, as a raw material for rib joints.

Claims

1. A resin composition for a ribbed joint for sewer pipes, comprising a vinyl chloride resin and a calcium-zinc stabilizer, wherein the calcium-zinc stabilizer contains a zeolite-based stabilizer, and the degree of polymerization of the vinyl chloride resin is 670 or less.

2. The resin composition according to claim 1, wherein the calcium-zinc stabilizer further contains a calcium salt of a fatty acid and a zinc salt of a fatty acid.

3. The resin composition according to claim 1 or 2, which is formed by injection molding.

4. A ribbed joint comprising the resin composition according to any one of claims 1 to 3. ​

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