JP2021030726A - Multilayer pipe - Google Patents

Abstract

To provide a multilayer pipe which is excellent in impact resistance and appearance.SOLUTION: A multilayer pipe 11 includes an inner layer 1 and an outer layer 2, in which the inner layer 1 contains a thermoplastic resin having a polar group, the outer layer 2 contains an acrylic urethane resin that is a reactant of an acrylic polyol compound and an isocyanate compound, the isocyanate compound contains a first isocyanate compound having a number average molecular weight of more than 1,500 and does not contain or contains a second isocyanate compound having a number average molecular weight of 100 or more and 1,500 or less, in the material of the reactant, a content of the first isocyanate compound is 20 pts.wt. or more and 30 pts.wt. or less with respect to 100 pts.wt. of the acrylic polyol compound, a content of the second isocyanate compound is 10 pts.wt. or less, and a content of a total of the first isocyanate compound and the second isocyanate compound is 20 pts.wt. or more and 35 pts.wt. or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multilayer tube including an inner layer and an outer layer.

In buildings such as condominiums, apartments, and detached houses, plastic pipes such as vinyl chloride resin pipes are often used for water supply and drainage. Further, as a pipe used outdoors, a pipe having an inner layer and an outer layer formed by applying a material having weather resistance is used. As the material having the above weather resistance, for example, acrylic lacquer, acrylic urethane paint, amino-acrylic resin paint and the like are used.

The following Patent Documents 1 and 2 disclose a resin composition having weather resistance.

Patent Document 1 below discloses a resin composition for a two-component acrylic urethane coating material in which a main agent containing an acrylic polyol as a main component and a curing agent which is a polyisocyanate are mixed and used at the time of use. In this resin composition for acrylic urethane coating material, the acrylic polyol contains a low molecular weight acrylic polyol (A) having a number average molecular weight of 7,000 or less and a high molecular weight acrylic polyol having a number average molecular weight of 10,000 or more (A). The mixing ratio of (B) and (B) is 0.5 ≦ (A) / (B) ≦ 9 in terms of weight ratio.

The following Patent Document 2 describes a coating composition containing (I) a hydroxyl group-containing graft copolymer having a hydroxyl value of 60 to 120, (II) a modified vinyl-based copolymer, and (III) a polyisocyanate compound. Is disclosed. The hydroxyl group-containing graft copolymers are (a) 10 to 30% by weight of macromonomer, (b) 0 to 30% by weight of styrene, and (c) 40 to 90% by weight of other ethylenically unsaturated monomers. Is obtained by copolymerizing. The (II) modified vinyl-based copolymer is obtained by copolymerizing (a) 5 to 75% by weight of cellulose acetate butyrate and (b) 95 to 25% by weight of the vinyl monomer mixture. The vinyl monomer mixture (b) is composed of at least 1 to 50% by weight of at least one functional vinyl monomer containing a hydroxyl group and 99 to 50% by weight of another copolymerizable vinyl monomer.

Japanese Unexamined Patent Publication No. 03-128982 Japanese Unexamined Patent Publication No. 06-0019949

When the resin composition having weather resistance as described in Patent Documents 1 and 2 is applied to the inner layer to form the outer layer, the weather resistance of the obtained pipe can be enhanced.

When the present inventor uses a composition containing an acrylic polyol compound and an isocyanate compound as the resin composition having weather resistance, the impact resistance of the obtained multilayer tube can be determined by the molecular weight and the blending amount of the isocyanate compound. It was found that it deteriorated and the appearance was poor. The present inventor has found that it is difficult to sufficiently enhance the impact resistance of the obtained multilayer tube when an outer layer containing an acrylic urethane resin is formed by using an isocyanate compound having a small molecular weight. Further, the present inventor of the present invention, when a composition containing an acrylic polyol compound and an isocyanate compound having an excessively large molecular weight is applied on the outer surface of the inner layer, the drying property of the composition becomes low, and when the outer layer is formed, the dryness of the composition becomes low. It has been found that the outer layer is easily damaged, and as a result, the resulting multilayer tube is likely to have a poor appearance.

As described above, it is difficult to improve the impact resistance and sufficiently suppress the appearance defect in the conventional multilayer tube provided with the outer layer containing the acrylic urethane resin.

An object of the present invention is to provide a multilayer tube having excellent impact resistance and excellent appearance.

According to a broad aspect of the present invention, the inner layer comprises an inner layer and an outer layer arranged on the outer surface of the inner layer, the inner layer contains a thermoplastic resin having a polar group, and the outer layer is an acrylic polyol compound and an isocyanate. A second isocyanate compound containing an acrylic urethane resin which is a reaction product with a compound, the isocyanate compound containing a first isocyanate compound having a number average molecular weight of more than 1500, and a number average molecular weight of 100 or more and 1500 or less. In the material of the reaction product, the content of the first isocyanate compound is 20 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound, and the second isocyanate is contained. Provided is a multilayer tube having a compound content of 10 parts by weight or less and a total content of the first isocyanate compound and the second isocyanate compound of 20 parts by weight or more and 35 parts by weight or less.

In a specific aspect of the multilayer tube according to the present invention, when the sample obtained by treating the outer layer with cresol is measured by gel permeation chromatography, 1000 or more and 7000 in 100% of the peak area derived from the isocyanate compound. The ratio of the peak area derived from the isocyanate compound appearing as the following molecular weight is 15% or more and 90% or less.

In certain aspects of the multilayer tube according to the present invention, the isocyanate compound comprises the second isocyanate compound.

In certain aspects of the multilayer tube according to the present invention, the first tensile elongation at break of the inner layer at 0 ° C. and 500 mm / min and the second multilayer tube at 0 ° C. and 500 mm / min. The absolute value of the difference from the tensile elongation at break is 30% or less.

In a specific aspect of the multilayer tube according to the present invention, when the adhesion test between the inner layer and the outer layer is performed by a cross-cut method in accordance with JIS K5600-5-6, the result of the adhesion test Is Category 0 or Category 1.

In certain aspects of the multilayer pipe according to the present invention, the multilayer pipe is a joint.

The multilayer tube according to the present invention includes an inner layer and an outer layer arranged on the outer surface of the inner layer, the inner layer contains a thermoplastic resin having a polar group, and the outer layer is an acrylic polyol compound and an isocyanate compound. Contains acrylic urethane resin, which is a reaction product with. In the multilayer tube according to the present invention, the isocyanate compound does not contain or contains a first isocyanate compound having a number average molecular weight of more than 1500 and a second isocyanate compound having a number average molecular weight of 100 or more and 1500 or less. .. In the multilayer tube according to the present invention, in the material of the reaction product, the content of the first isocyanate compound is 20 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound, and the second The content of the isocyanate compound is 10 parts by weight or less, and the total content of the first isocyanate compound and the second isocyanate compound is 20 parts by weight or more and 35 parts by weight or less. Since the multilayer tube according to the present invention has the above configuration, it has excellent impact resistance and an excellent appearance.

FIG. 1 is a cross-sectional view showing a multilayer tube according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

(Multi-layer tube)
The multilayer tube according to the present invention includes an inner layer and an outer layer arranged on the outer surface of the inner layer, the inner layer contains a thermoplastic resin having a polar group, and the outer layer is an acrylic polyol compound and an isocyanate compound. Contains acrylic urethane resin, which is a reaction product with.

In the multilayer tube according to the present invention, the isocyanate compound does not contain or contains a first isocyanate compound having a number average molecular weight of more than 1500 and a second isocyanate compound having a number average molecular weight of 100 or more and 1500 or less. ..

In the multilayer tube according to the present invention, in the material of the reaction product, the content of the first isocyanate compound is 20 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound, and the second The content of the isocyanate compound is 10 parts by weight or less. In the multilayer tube according to the present invention, the total content of the first isocyanate compound and the second isocyanate compound is 20 parts by weight or more with respect to 100 parts by weight of the acrylic polyol compound in the material of the reaction product. It is 35 parts by weight or less. The material of the reaction product is a material for obtaining the acrylic urethane resin in the material of the outer layer.

Since the multilayer tube according to the present invention has the above configuration, it has excellent impact resistance and an excellent appearance.

The multilayer tube according to the present invention is obtained, for example, by applying an outer layer material containing the acrylic polyol compound and the isocyanate compound having a specific molecular weight to the outer surface of the inner layer and drying the outer layer material. be able to. In the present invention, since the isocyanate compound having a specific molecular weight is used in a specific blending amount, the drying rate of the material of the outer layer can be increased. Therefore, damage to the outer layer can be suppressed when the outer layer is formed, and the appearance of the obtained multilayer tube can be improved. Further, in the present invention, the hardness of the outer layer can be increased, the surface of the outer layer is not easily scratched, and the appearance of the multilayer tube can be improved. Further, in the present invention, since the isocyanate compound having a specific molecular weight is used in a specific blending amount, the molecular weight between the cross-linking points of the acrylic urethane resin can be improved, and the flexibility of the acrylic urethane resin is improved. Can be. Therefore, the impact resistance of the obtained multilayer tube can be improved.

Furthermore, the present inventor states that when the outer layer is formed by a conventional resin composition having weather resistance, the impact resistance performance of the obtained multilayer tube is significantly lower than the impact resistance performance of the tube before the outer layer is formed. I found. On the other hand, in the multilayer tube of the present invention, the impact resistance of the multilayer tube can be maintained at the same level as the impact resistance before forming the outer layer.

Further, in the multilayer tube according to the present invention, the adhesiveness (adhesiveness) between the inner layer and the outer layer and the weather resistance of the multilayer tube can be improved. Therefore, in the present invention, mechanical strength such as impact resistance of the multilayer tube can be maintained for a long period of time.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the drawings below, the size, thickness, shape, etc. may differ from the actual size, thickness, shape, etc. for convenience of illustration.

FIG. 1 is a cross-sectional view showing a multilayer tube according to an embodiment of the present invention.

The multilayer tube 11 includes an inner layer 1 and an outer layer 2. The inner layer 1 is tubular. The inner layer 1 reaches the ends on both sides of the multilayer tube 11.

The outer layer 2 is arranged on the outer surface of the inner layer 1. The outer layer 2 is arranged on the entire outer surface of the inner layer 1. The outer layer preferably reaches the ends on both sides of the multilayer tube. The outer layer is preferably arranged in a tubular shape.

(Inner layer)
The inner layer contains a thermoplastic resin having a polar group. The inner layer is obtained by molding a material of the inner layer containing a thermoplastic resin having a polar group. Only one type of thermoplastic resin having the above polar groups may be used, or two or more types may be used in combination.

Examples of the polar group include a group having a halogen atom and an electron-attracting group such as a carbonyl group. Examples of the halogen atom include a fluorine atom and a chlorine atom.

Examples of the thermoplastic resin having a polar group include a polyvinyl chloride resin, a (meth) acrylic resin such as polymethyl methacrylate (PMMA), a carbonate resin such as polycarbonate (PC), and polyvinylidene fluoride (PVDF). Fluorescent resins and the like can be mentioned. Only one type of thermoplastic resin having the above polar groups may be used, or two or more types may be used in combination.

The vinyl chloride resin is not particularly limited. Examples of the vinyl chloride resin include a homopolymer of a vinyl chloride monomer, a copolymer of a vinyl chloride monomer and a monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer, and a polymer other than vinyl chloride and co-polymer. Examples thereof include a graft polymer in which vinyl chloride is graft-polymerized on the polymer. The vinyl chloride resin may be a rigid vinyl chloride resin.

The monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer is not particularly limited, and is an α-olefin compound such as ethylene, propylene or butylene; a vinyl ester compound such as vinyl acetate or vinyl propionate; butyl vinyl ether or cetyl. Vinyl ether compounds such as vinyl ether; (meth) acrylic acid ester compounds such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; N-phenylmaleimide , N-substituted maleimide compounds such as N-cyclohexyl maleimide and the like. As the monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer, only one kind may be used, or two or more kinds may be used in combination.

The polymer and copolymer for graft-copolymerizing vinyl chloride are not particularly limited, and are an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-carbon monoxide copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-. Examples thereof include butyl acrylate-carbon monoxide copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, chlorinated polypropylene and the like. As the polymer and copolymer for graft-copolymerizing vinyl chloride, only one kind may be used, or two or more kinds may be used in combination.

The content of the structural unit derived from vinyl chloride in 100% by weight of the vinyl chloride resin is preferably 70% by weight or more, more preferably 75% by weight or more, still more preferably 80% by weight or more, and particularly preferably 90% by weight. % Or more, preferably 98% by weight or less, and more preferably 95% by weight or less. When the content of the structural unit derived from vinyl chloride is at least the above lower limit, the impact resistance can be further enhanced. When the content of the structural unit derived from vinyl chloride is not more than the above upper limit, moldability can be enhanced, thermal decomposition of vinyl chloride can be suppressed during molding, and impact resistance, flatness and water resistance can be suppressed. The pressure property can be increased, and the appearance can be improved. The content of the structural unit derived from vinyl chloride in 100% by weight of the vinyl chloride resin may be 100% by weight (total amount).

The vinyl chloride resin may be used in combination with other organic materials as long as the effects of the present invention are not impaired. For example, in order to further improve the mechanical strength, an acrylic resin or the like may be used in combination with the vinyl chloride resin.

Further, the vinyl chloride resin may be a post-chlorinated vinyl chloride resin.

Examples of the polymethyl methacrylate (PMMA) include homopolymers of acrylic monomers. Only one type of polymethyl methacrylate (PMMA) may be used, or two or more types may be used in combination.

The acrylic monomer is not particularly limited, and methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobonyl (meth) acrylate, Cyclohexyl (meth) acrylate, glycidyl (meth) acrylate and the like can be mentioned. Only one kind of the acrylic monomer may be used, or two or more kinds may be used in combination.

The polymethyl methacrylate (PMMA) may be an acrylic polymer obtained by modifying the acrylic monomer.

Examples of the polycarbonate (PC) include reaction products of a dihydroxy compound, phosgene, and a carbonic acid diester or haloformate. Only one type of the above-mentioned polycarbonate (PC) may be used, or two or more types may be used in combination.

Examples of the dihydroxy compound include aromatic dihydroxy compounds such as bisphenol A, tetramethylbisphenol A, tetrabromobisphenol A, bis (4-hydroxyphenyl) -p-diisopropylbenzene, hydroquinone and resorcinol. The dihydroxy compound is preferably bisphenol A. Only one kind of the dihydroxy compound may be used, or two or more kinds thereof may be used in combination.

From the viewpoint of further enhancing the adhesiveness between the inner layer and the outer layer and the weather resistance of the multilayer tube, the thermoplastic resin having the polar group is preferably a vinyl chloride resin or a polycarbonate, and is a vinyl chloride resin. Is more preferable.

The degree of polymerization of the thermoplastic resin having a polar group is preferably 500 or more, more preferably 600 or more, preferably 2000 or less, and more preferably 1800 or less. When the degree of polymerization of the thermoplastic resin is at least the above lower limit, long-term performance such as fatigue characteristics is unlikely to be impaired. When the degree of polymerization of the thermoplastic resin is not more than the above upper limit, it is not necessary to keep the temperature at a high temperature during molding, and the processability is further improved.

In the 100% by weight of the inner layer, the content of the thermoplastic resin having the polar group is preferably 50% by weight or more, more preferably 60% by weight or more, preferably 80% by weight or less, more preferably 75% by weight. It is as follows. When the content of the thermoplastic resin having the polar group is not less than the above lower limit and not more than the above upper limit, the weather resistance and the impact resistance can be further improved.

The inner layer and the material of the inner layer may contain various additives, if necessary. Examples of the above additives include stabilizers, stabilizing aids, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, ultraviolet absorbers, light stabilizers, fillers, pigments, plasticizers and the like. Can be mentioned. Only one kind of the above-mentioned additive may be used, or two or more kinds thereof may be used in combination.

The stabilizer is not particularly limited, and examples thereof include a heat stabilizer and a heat stabilization aid. The heat stabilizer is not particularly limited, and examples thereof include an organotin stabilizer, a lead stabilizer, a calcium-zinc stabilizer, a barium-zinc stabilizer, and a barium-cadmium stabilizer. Examples of the organic tin stabilizer include dibutyl tin mercapto, dioctyl tin mercapto, dimethyl tin mercapto, dibutyl tin mercapto, dibutyl tin malate, dibutyl tin malate polymer, dioctyl tin malate, dioctyl tin malate polymer, dibutyl tin laurate, and the like. Examples thereof include dibutyltin laurate polymer. The heat stabilizing aid is not particularly limited, and examples thereof include epoxidized soybean oil, phosphoric acid ester, polyol, hydrotalcite, and zeolite. Only one kind of the above stabilizer may be used, or two or more kinds may be used in combination.

Examples of the lubricant include an internal lubricant and an external lubricant. The internal lubricant is used for the purpose of lowering the flow viscosity of the molten resin during molding and preventing frictional heat generation. The internal lubricant is not particularly limited, and examples thereof include butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, and bisamide. The external lubricant is used for the purpose of enhancing the sliding effect between the molten resin and the metal surface during molding. The external lubricant is not particularly limited, and examples thereof include paraffin wax, polyolefin wax, ester wax, and montanic acid wax. Only one kind of the above-mentioned lubricant may be used, or two or more kinds may be used in combination.

The processing aid is not particularly limited, and examples thereof include acrylic processing aids. Examples of the acrylic processing aid include alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2 million, and specifically, n-butyl acrylate-methyl methacrylate copolymer and n-butyl acrylate-methyl methacrylate copolymer. Examples thereof include 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymer. As the processing aid, only one kind may be used, or two or more kinds may be used in combination.

The impact modifier is not particularly limited, and examples thereof include methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, and acrylic rubber. Only one type of the impact modifier may be used, or two or more types may be used in combination.

The heat resistance improving agent is not particularly limited, and examples thereof include α-methylstyrene-based resins and N-phenylmaleimide-based resins. Only one kind of the heat resistance improving agent may be used, or two or more kinds thereof may be used in combination.

The antioxidant is not particularly limited, and examples thereof include phenolic antioxidants. Only one kind of the above-mentioned antioxidant may be used, or two or more kinds may be used in combination.

The ultraviolet absorber is not particularly limited, and examples thereof include a salicylic acid ester-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, and a cyanoacrylate-based ultraviolet absorber. Only one kind of the above-mentioned ultraviolet absorber may be used, or two or more kinds may be used in combination.

The light stabilizer is not particularly limited, and examples thereof include hindered amine-based light stabilizers. Only one kind of the above-mentioned light stabilizer may be used, or two or more kinds thereof may be used in combination.

The filler is not particularly limited, and examples thereof include calcium carbonate and talc. Only one kind of the filler may be used, or two or more kinds thereof may be used in combination.

The pigment is not particularly limited, and examples thereof include organic pigments and inorganic pigments. Examples of the organic pigments include azo-based organic pigments, phthalocyanine-based organic pigments, slene-based organic pigments, and dye lake-based organic pigments. Examples of the inorganic pigments include oxide-based inorganic pigments, molybdenum chromate-based inorganic pigments, sulfide / selenium-based inorganic pigments, and ferrosinide-based inorganic pigments. Only one kind of the above pigment may be used, or two or more kinds may be used in combination.

The plasticizer may be added for the purpose of improving processability at the time of molding. The plasticizer is not particularly limited, and examples thereof include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate. Only one type of the plasticizer may be used, or two or more types may be used in combination.

(Outer layer)
The outer layer contains an acrylic urethane resin which is a reaction product of an acrylic polyol compound and an isocyanate compound. The material of the outer layer contains an acrylic polyol compound and an isocyanate compound. The acrylic urethane resin has a structural unit derived from the acrylic polyol compound and a structural unit derived from the first isocyanate compound, and has or does not have a structural unit derived from the second isocyanate compound. The outer layer can be formed, for example, by applying an outer layer material containing an acrylic polyol compound and an isocyanate compound on the outer surface of the inner layer and reacting the acrylic polyol compound with the isocyanate compound.

Acrylic polyol compound:
Examples of the acrylic polyol compound include an ethylenically unsaturated bond-containing monomer having a hydroxyl group alone or a mixture thereof, and another ethylenically unsaturated bond-containing monomer copolymerizable therewith alone or a mixture thereof. Examples thereof include compounds obtained by copolymerizing the above. Examples of the ethylenically unsaturated bond-containing monomer having a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Be done. Only one kind of the acrylic polyol compound may be used, or two or more kinds may be used in combination.

From the viewpoint of further enhancing the weather resistance, the acrylic polyol compound is preferably hydroxyethyl acrylate or hydroxyethyl methacrylate.

The number average molecular weight of the acrylic polyol compound is preferably 4000 or more, more preferably 4500 or more, preferably 20000 or less, and more preferably 18000 or less. When the number average molecular weight is equal to or higher than the above lower limit, the entanglement between the molecules can be enhanced, the distance between the cross-linking points of the obtained acrylic urethane resin can be lengthened, and the tensile elongation at break of the outer layer can be increased, resulting in. , Impact resistance can be further improved. When the number average molecular weight is not more than the above upper limit, the viscosity of the outer layer material can be suppressed low, and the drying time after the outer layer material is applied to the inner layer can be shortened, so that the production efficiency can be improved. It is possible to maintain a good appearance of the multilayer tube.

The number average molecular weight of the acrylic polyol compound can be determined by gel permeation chromatography (GPC), intercrosslink molecular weight measurement, solid NMR method, or after hydrolysis of acrylic urethane resin or decomposition with supercritical alcohol, ¹ H. -NMR, ¹³ C-NMR, IR, GC, GC / MS, or GPC can be used for analysis. The number average molecular weight of the acrylic polyol compound is preferably the number average molecular weight measured by gel permeation chromatography (GPC). Hydrolysis of the acrylic urethane resin or decomposition with supercritical alcohol breaks the urethane bond of the acrylic urethane resin, so that a monomer can be obtained. By identifying the obtained monomer, the molecular structure of the acrylic polyol compound can be obtained. And the number average molecular weight can be obtained.

Isocyanate compound:
The material of the outer layer contains a first isocyanate compound having a number average molecular weight of more than 1500, and does not contain or contains a second isocyanate compound having a number average molecular weight of 100 or more and 1500 or less. The material of the outer layer may or may not contain the second isocyanate compound. Therefore, the outer layer may contain an acrylic urethane resin which is a reaction product of the acrylic polyol compound and the first isocyanate compound, and the acrylic polyol compound, the first isocyanate compound and the second isocyanate compound may be contained. It may contain an acrylic urethane resin which is a reaction product with.

It is preferable that the material of the outer layer contains the second isocyanate compound. When the material of the outer layer contains the second isocyanate compound, the dryness of the material of the outer layer can be improved, and the appearance of the obtained multilayer tube can be improved. Therefore, the outer layer preferably contains an acrylic urethane resin which is a reaction product of the acrylic polyol compound, the first isocyanate compound, and the second isocyanate compound.

The isocyanate compound contains the first isocyanate compound from the viewpoint of enhancing the adhesiveness between the inner layer and the outer layer and enhancing the impact resistance.

Examples of the first isocyanate compound and the second isocyanate compound include aliphatic isocyanate compounds, alicyclic isocyanate compounds, and aromatic isocyanate compounds. The isocyanate compound may be a diisocyanate compound or a polyisocyanate compound. Only one type of the isocyanate compound may be used, or two or more types may be used in combination. Specific examples of the isocyanate compound include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), 1,4-cyclohexanediisocyanate, dicyclohexylmethanediisocyanate, and bis (isocyanatomethyl). An aliphatic or alicyclic diisocyanate compound such as cyclohexane (HXDI), tolylene diisocyanate (TDI), diphenylmethane isocyanate (MDI), p-phenylenediisocyanate (PPDI), xylene diisocyanate (XDI), diphenyl ether diisocyanate, trizine diisocyanate, dianisidine. Diisocyanate, aromatic diisocyanate compounds such as naphthalenediocyanate (NDI), cludetrilenisocyanate (crude TDI), polymethylenepolyphenylene polyisocyanate (polymeric MDI), triphenylmethanetriisocyanate, tris (phenylisocyanate) thiophosphate and the like. Examples thereof include aromatic polyisocyanate compounds and modified products of the above diisocyanate compounds. Examples of the modified product include isocyanurate modified products, burette modified products, carbodiimide modified products and the like.

From the viewpoint of effectively suppressing discoloration to yellow when the multilayer tube is installed outdoors and further enhancing the weather resistance, the first isocyanate compound and the second isocyanate compound are aliphatic isocyanate compounds. Is preferable.

From the viewpoint of shortening the drying time after applying the material of the outer layer to the inner layer, the first isocyanate compound and the second isocyanate compound are preferably aromatic isocyanate compounds.

In the multilayer tube according to the present invention, when the sample obtained by treating the outer layer with cresol is measured by gel permeation chromatography, it appears as a molecular weight of 1000 or more and 7000 or less in 100% of the peak area derived from the isocyanate compound. The ratio of the peak area derived from the isocyanate compound is preferably 15% or more and 90% or less. In this case, the effect of the present invention is exhibited even more effectively. In particular, the impact resistance can be effectively enhanced and the appearance can be further improved. The ratio of the peak area derived from the isocyanate compound appearing as a molecular weight of 1000 or more and 7,000 or less in 100% of the peak area derived from the isocyanate compound may be hereinafter referred to as the peak area ratio (X).

By treating the outer layer with cresol, the acrylic urethane resin contained in the outer layer is decomposed into an acrylic polyol compound and an isocyanate compound. Further, by treating the outer layer with cresol, a multimer isocyanate compound such as a trimer is decomposed into a monomeric isocyanate compound. Therefore, when the sample obtained by treating the outer layer with cresol is measured by gel filtration chromatography, when the first isocyanate compound is a monomeric isocyanate compound, "a peak derived from the first isocyanate compound". , The peak of the first isocyanate compound is detected. Further, when the sample obtained by treating the outer layer with cresol by gel filtration chromatography is measured, when the first isocyanate compound is a multimeric isocyanate compound, "peak derived from the first isocyanate compound". As a result, a peak derived from the first isocyanate compound decomposed to the monomer is detected.

The ratio (X) of the peak area is 15% or more and 90% or less. The ratio (X) of the peak area is preferably 20% or more, preferably 35% or less, and more preferably 30% or less. When the ratio (X) of the peak area is at least the above lower limit, the weather resistance and the impact resistance can be further improved. When the ratio (X) of the peak area is not more than the above upper limit, the drying time after applying the material of the outer layer to the inner layer can be shortened, so that the production efficiency can be improved and the appearance of the multilayer tube can be improved. Can be kept good.

Gel permeation chromatography (GPC) can be measured, for example, by the method described in Examples.

The number average molecular weight of the first isocyanate compound is not particularly limited as long as it exceeds 1500.

The number average molecular weight of the first isocyanate compound is preferably 2000 or more, more preferably 3000 or more, still more preferably 4000 or more, preferably 7000 or less, more preferably 6000 or less, still more preferably 5000 or less. When the number average molecular weight is equal to or higher than the above lower limit, the entanglement between the molecules can be enhanced, the distance between the cross-linking points of the obtained acrylic urethane resin can be lengthened, and the tensile elongation at break of the outer layer can be increased, resulting in. , Impact resistance can be further improved. When the number average molecular weight is not more than the above upper limit, the viscosity of the outer layer material can be suppressed low, and the drying time after the outer layer material is applied to the inner layer can be shortened, so that the production efficiency can be improved. It is possible to maintain a good appearance of the multilayer tube.

The number average molecular weight of the second isocyanate compound is 100 or more and 1500 or less. The number average molecular weight of the second isocyanate compound is preferably 120 or more, more preferably 150 or more, preferably 500 or less, more preferably 480 or less, still more preferably 450 or less. When the number average molecular weight is not less than the above lower limit and not more than the above upper limit, an acrylic urethane resin having a short distance between cross-linking points and a high cross-linking density can be satisfactorily obtained, and the hardness of the acrylic urethane resin can be increased.

The number average molecular weights of the first isocyanate compound and the second isocyanate compound can be analyzed by gel permeation chromatography (GPC), intercrosslinking molecular weight measurement, solid NMR method, or by hydrolyzing or superimposing acrylic urethane resin. After decomposition with critical alcohol ^{, it can be determined by 1} H-NMR, ¹³ C-NMR, IR, GC, GC / MS, or a method of analysis by GPC. The number average molecular weight of the isocyanate compound is preferably the number average molecular weight measured by gel permeation chromatography (GPC). In the hydrolysis of the acrylic urethane resin or the decomposition with supercritical alcohol, the urethane bond of the acrylic urethane resin is broken, so that a monomer can be obtained. By identifying the obtained monomer, the molecular structure of the isocyanate compound and the molecular structure and The number average molecular weight can be obtained. However, in the hydrolysis of the acrylic urethane resin or the decomposition with a supercritical alcohol, the trimeric isocyanate compound is decomposed into a dimer. It is necessary to identify the structure by MS or the like.

The second isocyanate compound is preferably a dimer or a trimer. The second isocyanate compound preferably has two or three isocyanate groups. In this case, a three-dimensional network structure can be formed, and the adhesiveness between the inner layer and the outer layer can be further enhanced.

The molecular structure of the isocyanate compound used in the acrylic urethane resin ^{can be analyzed by 1} H-NMR, ¹³ C-NMR, IR measurement and the like. Further, the molecular structure and the number average molecular weight of the isocyanate compound can be analyzed by analyzing the unreacted isocyanate compound contained in the acrylic urethane resin by thermal decomposition GCMS.

In the material of the reaction product or the material of the outer layer, the content of the first isocyanate compound is 20 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound. When the content of the first isocyanate compound is less than 20 parts by weight, the impact resistance of the obtained multilayer tube tends to decrease. When the content of the first isocyanate compound exceeds 30 parts by weight, the dryness of the material of the outer layer is lowered, and the appearance of the obtained multilayer tube may be poor.

In the material of the reaction product or the material of the outer layer, the content of the first isocyanate compound is preferably 25 parts by weight or more with respect to 100 parts by weight of the acrylic polyol compound. When the content of the first isocyanate compound is at least the above lower limit, the impact resistance, weather resistance and water resistance of the obtained multilayer tube can be further improved, and the appearance can be further improved. it can.

In the acrylic urethane resin contained in the outer layer, the content of the structural unit derived from the first isocyanate compound is preferably 20 parts by weight or more with respect to 100 parts by weight of the structural unit derived from the acrylic polyol compound. It is more preferably 25 parts by weight or more, and preferably 30 parts by weight or less. When the content of the structural unit derived from the first isocyanate compound is at least the above lower limit and at least the above upper limit, the impact resistance, weather resistance and water resistance of the multilayer tube can be further improved, and the appearance can be improved. It can be made even better.

In the material of the reaction product or the material of the outer layer, the content of the second isocyanate compound is 10 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound. When the isocyanate compound contains the second isocyanate compound, the content of the second isocyanate compound is 0 weight by weight with respect to 100 parts by weight of the acrylic polyol compound in the material of the reaction product or the material of the outer layer. It is more than 10 parts by weight or less. The content of the second isocyanate compound may be 0 parts by weight (not compounded). If the content of the second isocyanate compound exceeds 10 parts by weight, the outer layer becomes excessively hard and the impact resistance tends to decrease. When the content of the second isocyanate compound is 0 parts by weight (not compounded), the impact resistance can be improved, but the drying property of the outer layer material may be inferior.

In the material of the reaction product or the material of the outer layer, the content of the second isocyanate compound is preferably 0 parts by weight or more, more preferably 5 parts by weight or more, based on 100 parts by weight of the acrylic polyol compound. .. When the content of the second isocyanate compound is at least the above lower limit and at least the above upper limit, the impact resistance, weather resistance and water resistance of the obtained multilayer tube can be further enhanced, and the appearance is further improved. Can be.

In the acrylic urethane resin contained in the outer layer, the content of the structural unit derived from the second isocyanate compound is preferably 0 parts by weight or more with respect to 100 parts by weight of the structural unit derived from the acrylic polyol compound. It is preferably 5 parts by weight or more, and preferably 10 parts by weight or less. When the content of the structural unit derived from the second isocyanate compound is at least the above lower limit and at least the above upper limit, the impact resistance, weather resistance and water resistance of the multilayer tube can be further improved, and the appearance can be improved. It can be made even better.

In the material of the reaction product or the material of the outer layer, the total content of the first isocyanate compound and the second isocyanate compound is 20 parts by weight or more and 35 parts by weight with respect to 100 parts by weight of the acrylic polyol compound. It is as follows. When the total content is less than 20 parts by weight, the content of the acrylic polyol compound may be too large, and the impact resistance, weather resistance and water resistance of the obtained multilayer tube may be lowered. Further, when the total content exceeds 35 parts by weight, the content of the isocyanate compound becomes too large, the dryness of the material of the outer layer is lowered, and the appearance of the obtained multilayer tube may be poor. is there.

When the material of the outer layer does not contain the second isocyanate compound, the total content of the first isocyanate compound and the second isocyanate compound means the first isocyanate compound. ..

In the material of the reaction product or the material of the outer layer, the total content of the first isocyanate compound and the second isocyanate compound is preferably 25 parts by weight or more with respect to 100 parts by weight of the acrylic polyol compound. It is preferably 30 parts by weight or less. When the total content is not less than the above lower limit and not more than the above upper limit, the impact resistance, weather resistance and water resistance of the obtained multi-layer pipe can be further enhanced, and the appearance of the obtained multi-layer pipe can be further improved. Can be good.

In the acrylic urethane resin contained in the outer layer, the content of the structural unit derived from the first isocyanate compound and the content derived from the second isocyanate compound are derived from 100 parts by weight of the structural unit derived from the acrylic polyol compound. The total with the content of the structural unit is preferably 20 parts by weight or more, more preferably 25 parts by weight or more, preferably 35 parts by weight or less, and more preferably 30 parts by weight or less. When the total of the content of the structural unit derived from the first isocyanate compound and the content of the structural unit derived from the second isocyanate compound is equal to or more than the above lower limit and not more than the above upper limit, the impact resistance of the multilayer tube , Weather resistance and water resistance can be further improved, and the appearance of the multilayer tube can be further improved.

Urethane catalyst:
The material of the outer layer preferably contains a urethanization catalyst. Examples of the urethanization catalyst include dibutyltin dilaurate, dibutyltin di (2-ethylhexoate), tin chloride, and tetra-n-butyltin.

From the viewpoint of increasing reactivity, the urethanization catalyst is preferably dibutyltin dilaurate.

The content of the urethanization catalyst is preferably 0.01 parts by weight or more, and preferably 0.5 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound contained in the material of the outer layer. When the content of the urethanization catalyst is at least the above lower limit, the drying time after applying the material of the outer layer to the inner layer can be shortened. When the content of the urethanization catalyst is not more than the above upper limit, the production cost can be suppressed.

Pigment:
From the viewpoint of further enhancing the weather resistance, the outer layer and the material of the outer layer preferably contain a pigment. Examples of the pigment include colored pigments, extender pigments, aluminum flakes and the like. Only one kind of the above pigment may be used, or two or more kinds may be used in combination.

From the viewpoint of further enhancing the weather resistance, the pigment is preferably an inorganic pigment.

Examples of the inorganic pigment include zinc oxide, cobalt oxide, iron oxide, carbon black, antimony oxide, titanium oxide, chromium oxide, lead chromate chromate sulfate, calcium carbonate, zinc sulfide and the like.

From the viewpoint of effectively suppressing heat generation of the pigment due to light absorption and effectively suppressing deterioration of the outer layer, the inorganic pigment preferably contains titanium oxide.

The average particle size of the inorganic pigment is preferably 100 nm or more, more preferably 120 nm or more, preferably 800 nm or less, and more preferably 750 nm or less. When the average particle size of the inorganic pigment is at least the above lower limit, the weather resistance can be further improved, and the mechanical properties can be maintained well for a long period of time. When the average particle size of the inorganic pigment is not more than the above upper limit, weather resistance and impact resistance can be further improved.

The average particle size of the inorganic pigment indicates a number average particle size. The average particle size of the inorganic pigment can be obtained, for example, by performing a laser diffraction type particle size distribution measurement.

<Solvent>
The material of the outer layer preferably contains a solvent from the viewpoint of enhancing the adhesiveness between the inner layer and the outer layer, improving the coatability, and satisfactorily arranging the outer layer on the outer surface of the inner layer. For example, the outer layer can be formed by applying a solvent-containing outer layer material on the outer surface of the inner layer and then volatilizing the solvent. Only one type of the solvent may be used, or two or more types may be used in combination.

From the viewpoint of further enhancing the adhesiveness between the inner layer and the outer layer and further enhancing the coatability, the solvent is preferably an organic solvent.

Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate, normal butyl acetate and cellosolve acetate. Can be mentioned.

From the viewpoint of further enhancing the adhesiveness between the inner layer and the outer layer and enhancing the impact resistance, the organic solvent is preferably normal butyl acetate.

<Other ingredients>
The outer layer material may contain, for example, a leveling agent, a sedimentation inhibitor, and the like, if necessary.

(Other details of multi-layer tube)
The multilayer tube may have a two-layer structure of the inner layer and the outer layer, or may have a structure of three or more layers. The outer layer is preferably the outermost layer of the multilayer tube. The inner layer may be the innermost layer of the multilayer tube, or may be a layer other than the innermost layer.

The multilayer pipe may be a straight pipe or a pipe having a bending angle. Examples of the pipe having the bending angle include a T-shaped pipe and an L-shaped pipe.

The multilayer pipe may be a joint.

In the multilayer tube, the first tensile elongation at break of the inner layer under the conditions of 0 ° C. and 500 mm / min is preferably 40% or more, more preferably 45% or more, preferably 55% or less, more preferably. Is less than 50%. When the first tensile elongation at break is at least the above lower limit and at least the above upper limit, the impact resistance can be further enhanced.

In the above-mentioned multilayer tube, the second tensile elongation at break of the multilayer tube under the conditions of 0 ° C. and 500 mm / min is preferably 10% or more, more preferably 15% or more, preferably 50% or less, more preferably. Is 45% or less. When the second tensile elongation at break is at least the above lower limit, the impact resistance can be enhanced and the flatness can also be enhanced. When the second tensile elongation at break is not more than the above upper limit, stress concentration on the joint portion due to heat shrinkage or the like can be suppressed even if the multilayer pipe is used as a joint in a place where the temperature is relatively high. It is possible to suppress cracks or cracks in the multilayer tube.

The first tensile elongation at break and the second elongation at break are more specifically determined in accordance with JIS K6815 under the conditions of 0 ° C. and 500 mm / min.

It is preferable that the first tensile elongation at break and the second tensile elongation at break are the same, or the first tensile elongation at break is larger than the second tensile elongation at break. In this case, even if the multilayer tube is deformed by an external impact, the outer layer can follow the deformation of the inner layer well, so that the impact resistance can be improved.

From the viewpoint of enhancing impact resistance and flatness, the absolute value of the difference between the first tensile elongation at break and the second elongation at break is preferably 30% or less, more preferably 20% or less. is there. It is preferable that the absolute value of the difference between the first tensile elongation at break and the second elongation at break is small.

From the viewpoint of improving the adhesiveness between the inner layer and the outer layer and suppressing the outer layer from peeling off after installing the multi-layer pipe, for example, the multi-layer pipe is in accordance with JIS K5600-5-6, and the inner layer and the above are described. When the adhesion test with the outer layer is performed by the cross-cut method, the result of the adhesion test is preferably Category 0 or Category 1, and most preferably Category 0.

JIS K5600-5-6 defines six classifications, classifications 0 to 5, as a result of the adhesion test. The closer it is to classification 0, the better the adhesiveness.

From the viewpoint of effectively suppressing the arrival of sunlight or the like to the inner layer and further enhancing the weather resistance, the total light transmittance in the thickness direction of the outer layer is preferably 50% or less, more preferably 30% or less, and further. It is preferably 10% or less.

The outer layer for measuring the total light transmittance may be obtained by cutting out the outer layer from the multilayer tube, or by molding the material of the outer layer to prepare a layer having the same thickness as the outer layer in the multilayer tube. You may.

The total light transmittance is measured according to JIS K7361-1.

From the viewpoint of actual use, the thickness of the multilayer tube is preferably 2 mm or more, more preferably 4 mm or more, preferably 15 mm or less, and more preferably 12 mm or less.

From the viewpoint of actual use and further enhancing the weather resistance, the thickness of the inner layer is preferably 1 mm or more, more preferably 4 mm or more, preferably 14.5 mm or less, and more preferably 13 mm or less.

From the viewpoint of actual use and further enhancing the weather resistance, the thickness of the outer layer is preferably 0.01 mm or more, more preferably 0.1 mm or more, preferably 1 mm or less, more preferably 0.5 mm. It is as follows. In particular, when the thickness of the outer layer is at least the above lower limit, the weather resistance can be enhanced. In particular, when the thickness of the outer layer is not more than the above upper limit, the appearance can be improved.

(Manufacturing method of multi-layer pipe)
Examples of the method for manufacturing the multilayer tube include a method of forming the outer layer by applying the material of the outer layer on the outer surface of the inner layer. By drying the material of the outer layer applied on the outer surface of the inner layer, the outer layer can be formed on the outer surface of the inner layer. The outer layer is preferably a coating film.

Examples of the method for applying the material of the outer layer include spray coating and coating by a brush or the like.

The method of applying the material of the outer layer is preferably spray coating. By spray-coating the material of the outer layer on the outer surface of the inner layer, for example, even when the inner layer has a complicated shape, the outer layer can be easily and uniformly arranged on the outer surface of the inner layer. As a result, a multilayer tube having excellent weather resistance and impact resistance can be obtained. Further, in the above spray coating, the construction time can be shortened and the construction cost can be reduced.

The coating thickness of the outer layer material is preferably 0.01 mm or more, more preferably 0.1 mm or more, preferably 1 mm or less, and more preferably 0.5 mm or less. When the coating thickness is not less than the above lower limit and not more than the above upper limit, the thickness of the outer layer can be satisfactorily controlled within the above preferable range, and the weather resistance can be further improved. Further, when the coating thickness is not more than the above upper limit, dripping during coating can be suppressed, the solvent can be satisfactorily volatilized, and further, peeling of the outer layer can be effectively suppressed.

In the material of the outer layer containing the acrylic polyol compound and the isocyanate compound, the acrylic urethane resin may be synthesized before the coating on the outer surface of the inner layer or after the coating on the outer surface of the inner layer. Good.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

The following are prepared as the inner layer.

Straight pipe 1A: "Eslon Plant VP Pipe" manufactured by Sekisui Chemical Co., Ltd., caliber 50A
Straight pipe 2A: "Eslon HI pipe" manufactured by Sekisui Chemical Co., Ltd., caliber 50A
Straight pipe 3A: "Eslon normal VP pipe" manufactured by Sekisui Chemical Co., Ltd., caliber 50A
Straight pipe 1B: Polycarbonate pipe, caliber 50A
Straight pipe 1C: "Eslon Hyper JW" manufactured by Sekisui Chemical Co., Ltd., caliber 50A
Fitting body 1: "Eslon TS socket fitting" manufactured by Sekisui Chemical Co., Ltd., caliber 50A

The straight pipes 1A, 2A, 3A and the joint body 1 include a rigid vinyl chloride resin (thermoplastic resin having a polar group). Further, the straight tube 1B contains polycarbonate (a thermoplastic resin having a polar group). Further, the straight pipe 1C contains polyethylene (a thermoplastic resin having no polar group).

The following were prepared as the materials for the outer layer.

(Acrylic polyol compound and isocyanate compound)
"High Art CB Eco White" manufactured by Isamu Paint Co., Ltd. (including acrylic polyol compound with a number average molecular weight of 10,000)
"Multisoftener" manufactured by Isamu Paint Co., Ltd. (first isocyanate compound containing a trimer isocyanate compound having a number average molecular weight of 15,000)
"High Art CB Eco-Hardener Standard" manufactured by Isamu Paint Co., Ltd. (second isocyanate compound containing a trimer isocyanate compound with a number average molecular weight of 300)

(Urethane catalyst)
Tin catalyst: "Urethane drying accelerator" manufactured by Isamu Paint Co., Ltd.

(Aqueous acrylic urethane paint)
"Vinirose White" manufactured by Dai Nippon Toryo Co., Ltd. (including 30 parts by weight of the first isocyanate compound with respect to 100 parts by weight of the acrylic polyol compound)

(solvent)
Normal Butyl Acetate: "High Art CB Eco Thinner" manufactured by Isamu Paint Co., Ltd.
water

(Example 1)
A joint body 1 was prepared as an inner layer.

The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 30 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 5 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

The obtained outer layer material is spray-coated on the entire outer surface of the joint body 1 under the conditions of a spray pressure of 0.2 MPa and 23 ° C. using "TPU-65-0025-SS" manufactured by Spraying System Japan GK. did. After the spray application, it was naturally dried at 23 ° C., and the drying property described later was evaluated. Then, the obtained outer layer material was spray-coated over the entire outer surface of the naturally dried layer in the same manner. After spray application, it is dried at 60 ° C. for 30 minutes to completely volatilize normal butyl acetate (solvent), and react the acrylic polyol with the first isocyanate compound and the second isocyanate compound to contain an acrylic urethane resin. The outer layer was formed. The thickness of the outer layer was 0.025 mm. In this way, a multi-layer pipe (joint) including an inner layer (joint body) and an outer layer was obtained.

(Example 2)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 20 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 10 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Examples 3 to 5, 7)
A multilayer tube having an inner layer and an outer layer was obtained in the same manner as in Example 1 except that the materials of the inner layer and the outer layer shown in Table 1 were used.

(Example 6)
100 parts by weight of "Vinirose White" manufactured by Dai Nippon Toryo Co., Ltd. and 20 parts by weight of water were mixed to obtain a material for the outer layer. A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 1)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 40 parts by weight Isamu Paint's "High Art CB Eco Thinner" 40 parts by weight Isamu Paint's "Urethane Drying Accelerator" 0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 2)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 10 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 15 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 3)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 20 parts by weight Isamu Paint's "High Art CB Eco Thinner" 40 parts by weight Isamu Paint's "Urethane Drying" Accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 4)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 40 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 10 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 5)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 20 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 15 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 6)
The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 30 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 10 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

A multilayer pipe (joint) having an inner layer (joint body) and an outer layer was obtained in the same manner as in Example 1 except that the obtained outer layer material was used.

(Comparative Example 7)
The inner layer shown in Table 2 was used.

The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 10 parts by weight Isamu Paint's "High Art CB Eco Thinner" 40 parts by weight Isamu Paint's "Urethane Drying" Accelerator "0.5 parts by weight

Except for these, a multilayer tube having an inner layer and an outer layer was obtained in the same manner as in Example 1.

(Comparative Example 8)
The inner layer shown in Table 2 was used.

The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 30 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 10 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

Except for these, a multilayer tube having an inner layer and an outer layer was obtained in the same manner as in Example 1.

(Comparative Example 9)
The inner layer shown in Table 2 was used.

The following components were mixed at the following compounding ratio at 23 ° C. to obtain a material for the outer layer.

Isamu Paint's "High Art CB Eco White" 100 parts by weight Isamu Paint's "Multi Softener" 30 parts by weight Isamu Paint's "High Art CB Eco Hardener Standard" 5 parts by weight Isamu Paint's "High Art CB Eco" Thinner "40 parts by weight Isamu Paint Co., Ltd." Urethane drying accelerator "0.5 parts by weight

The obtained outer layer material is spray-coated on the entire outer surface of the straight pipe 1C under the conditions of a spray pressure of 0.2 MPa and 23 ° C. using "TPU-65-0025-SS" manufactured by Spraying System Japan GK. As a result, the material of the outer layer was repelled by the surface of the inner layer, and the material of the outer layer could not be applied on the outer surface of the inner layer.

(Evaluation)
(1) Percentage of peak area derived from isocyanate compound appearing as a molecular weight of 1000 or more and 7000 or less (X)
Cresol treatment:
The outer layer was cut from the obtained multilayer tube. 5 g of the obtained outer layer and 60 g of cresol were mixed, heated in a nitrogen atmosphere, heated to 204 ° C., and held at 204 ° C. for 4 hours for reaction. The post-reaction mixture was then cooled to room temperature to precipitate a solid. The cresol was then evaporated at 100 ° C. and 0.2 mbr to give a solid.

The obtained solid was separated by extracting a polyol using a solvent (hexane).

Measurement by gel permeation chromatography:
The obtained solid was dissolved in tetrahydrofuran (THF) so that the content in the sample was 0.2% by weight. The obtained sample was measured by gel permeation chromatography (GPC) under the following conditions. Based on the obtained peak, the ratio (X) of the peak area derived from the isocyanate compound appearing as a molecular weight of 1000 or more and 7000 or less in 100% of the peak area derived from the isocyanate compound was determined. The molecular weight was calculated by creating a calibration curve using standard polystyrene.

Equipment: Waters "ACQUITY APC system wasiyoshi"
Column: "HSPgel HR MB-M" manufactured by Waters (particle diameter 3.5 μm, 6.0 mm × 150 mm)
Column temperature: 40 ° C
Flow velocity: 0.5 mL / min
Injection volume: 10.0 μL

(2) Applyability The coatability of the obtained outer layer material when spray-applied to the outer surface of the inner layer was evaluated according to the following criteria.

[Criteria for wettability]
◯: The material of the outer layer can be spray-coated on the outer surface of the inner layer ×: The material of the outer layer cannot be spray-coated on the outer surface of the inner layer (repelled by the surface of the inner layer)

(3) Dryness of Outer Layer Material The obtained outer layer material was spray-coated on the outer surface of the inner layer. After spray application, the mixture was left at 23 ° C., the coating film was lightly touched with a finger, and the time until the sticky feeling disappeared was measured.

[Criteria for dryness]
◯: The time until the sticky feeling disappears is 15 minutes or less ×: The time until the sticky feeling disappears exceeds 15 minutes

(4) Appearance (surface hardness and surface scratch resistance)
The obtained multilayer tube was evaluated for the following surface hardness and the following surface scratch resistance to evaluate the appearance.

(4-1) Surface hardness The surface hardness of the outer layer was measured according to ISO14577 using a nanoindenter measuring machine. The test load was 1 mN.

(4-2) Surface Scratchability The obtained multilayer tube was subjected to a scratch hardness test in accordance with JIS K5600-5-4.

[Criteria for surface scratchiness]
◯: H or more Δ: 2B to F
×: 3B or less

(5) Weather resistance test (color difference)
The obtained multilayer tube was subjected to an 800-hour weather resistance test under the following conditions. As a weather resistance tester, "METALWEATHER" manufactured by Daiprowintes Co., Ltd. was used.

[Weather resistance test conditions]
Operation mode: L + D
L: Irradiation intensity 75 mW / cm ² , black panel temperature 50 ° C, humidity 50%, 4 hours D: No irradiation, black panel temperature 30 ° C, humidity 98%, 4 hours Shower: 30 seconds before and after D

The L, a, and b values of the multilayer tubes before and after the weather resistance test were measured using a color difference meter "NR-300" manufactured by Nippon Denshoku Kogyo Co., Ltd. in accordance with JIS-Z8730. From the L, a, b values of the multi-layer pipe before the weather resistance test and the L, a, b values of the multi-layer pipe after the weather resistance test, the color difference was calculated by the following formula.

ΔE = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^1/2

(6) Total light transmittance in the thickness direction of the outer layer The material of the outer layer used was applied onto a PTFE sheet, and the thickness was 0.005 mm, 0.01 mm, 0.03 mm, 0.05 mm, 0.10 mm, 0.20 mm. A coating film was prepared. Since the thickness of each of the obtained coating films varied by ± 0.005 mm, an accurate thickness was measured with a micrometer.

The total light transmittance of the obtained coating film was measured using "NDH2000" manufactured by Nippon Denshoku Kogyo Co., Ltd. in accordance with JIS K7361-1. On a semi-logarithmic graph, the thickness of the coating film was plotted on the horizontal axis and the total light transmittance was plotted on the vertical axis, and the slope of the obtained approximate straight line was defined as a constant A. According to the following formula, the total light transmittance in the thickness direction of the outer layer (the outer layer having the same thickness as the outer layer in the obtained multilayer tube) was calculated. The smaller the total light transmittance, the better the weather resistance of the multilayer tube.

Total light transmittance (%) in the thickness direction of the outer layer = 100 × exp (−A × T)
T: Thickness of outer layer (mm)

[Criteria for determining total light transmittance in the thickness direction of the outer layer]
◯: Total light transmittance in the thickness direction of the outer layer is 30% or less ×: Total light transmittance in the thickness direction of the outer layer exceeds 30%

(7) Tensile breaking elongation rate The outer layer of the obtained multilayer tube was ground with a grinding machine to obtain an inner layer. The tensile elongation at break of the inner layer (first tensile elongation at break) and the tensile elongation at break of the multilayer tube (second tensile elongation at break) are measured by a tensile tester (Shimadzu Seisakusho's "Desktop Precision Universal Testing Machine". AGX-X ") was used for measurement at 0 ° C. and 500 mm / min in accordance with JIS K6815.

(8) Drop weight impact test (50% impact fracture height)
The inner layer used and the obtained multi-layer pipe were subjected to a weight drop impact test at 0 ° C. using a flat-bottomed weight with a weight of 3 kg in accordance with JIS K6742 Annex JA and JIS K6743 Annex JA. Impact test) was carried out. From the measurement results, the 50% impact fracture height was calculated according to JIS K7211. As the drop weight tester, "FALLING DART IMPACT TESTER" manufactured by Yasuda Seiki Seisakusho Co., Ltd. was used.

Further, the retention rate of the 50% impact fracture height of the multilayer pipe was calculated according to the following formula.

Retention rate of 50% impact fracture height of multi-layer pipe (%) = (50% impact fracture height of multi-layer pipe (cm) / 50% impact fracture height of inner layer (cm)) x 100

[Criteria for drop weight impact test (50% impact fracture height)]
◯: 50% impact fracture height retention rate of multi-layer pipe is 50% or more Δ: 50% impact fracture height retention rate of multi-layer pipe is 30% or more and less than 50% ×: 50% impact fracture height of multi-layer pipe Retention rate is less than 30%

(9) Impact strength retention rate 50% impact fracture of the multilayer pipe after the weather resistance test (color difference) obtained in the above weather resistance test (color difference) in the same manner as in the above drop weight impact test (50% impact fracture height). I asked for the height. From the 50% impact fracture height of the multilayer pipe before and after the weather resistance test, the impact strength retention rate was determined according to the following formula.

Impact strength retention rate (%) = (50% impact fracture height (cm) of multi-layer pipe after weather resistance test / 50% impact fracture height (cm) of multi-layer pipe before weather resistance test) x 100

[Criteria for impact strength retention]
◯: Impact strength retention rate is 60% or more ×: Impact strength retention rate is less than 60%

(10) Adhesion test between inner layer and outer layer (adhesion between inner layer and outer layer)
The obtained multilayer tube was subjected to an adhesion test between the inner layer and the outer layer by a cross-cut method in accordance with JIS K5600-5-6. Specifically, it was carried out as follows. The obtained multilayer tube was cut into a size of 150 mm × 100 mm to obtain a test sample. A utility knife with a 20 degree blade and an evenly spaced spencer were used to make a total of 7 cuts in the outer layer of the test sample at 2 mm intervals. Then, the same operation was performed at 90 degrees to this notch to form a grid pattern. A transparent pressure-sensitive adhesive tape having an adhesion strength of 10 N per 25 mm × 25 mm was attached to the formed lattice pattern portion, and then separated at an angle of 60 degrees and at 0.5 seconds to 1.0 seconds. The number of outer layers peeled off from the lattice pattern was counted and classified according to the classification of the test results described in JIS K5600-5-6.

The configurations and results of the multilayer pipes are shown in Tables 1 and 2 below.

1 ... Inner layer 2 ... Outer layer 11 ... Multilayer tube

Claims (6)

The inner layer and the outer layer arranged on the outer surface of the inner layer are provided.
The inner layer contains a thermoplastic resin having a polar group and contains.
The outer layer contains an acrylic urethane resin which is a reaction product of an acrylic polyol compound and an isocyanate compound.
The isocyanate compound does not contain or contains a first isocyanate compound having a number average molecular weight of more than 1500 and a second isocyanate compound having a number average molecular weight of 100 or more and 1500 or less.
In the material of the reactant, the content of the first isocyanate compound is 20 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the acrylic polyol compound, and the content of the second isocyanate compound is 10. A multilayer tube having a weight of parts by weight or less and a total content of the first isocyanate compound and the second isocyanate compound of 20 parts by weight or more and 35 parts by weight or less. When the sample obtained by treating the outer layer with cresol is measured by gel permeation chromatography, the peak area derived from the isocyanate compound appearing as a molecular weight of 1000 or more and 7000 or less in 100% of the peak area derived from the isocyanate compound. The multilayer tube according to claim 1, wherein the ratio is 15% or more and 90% or less. The multilayer tube according to claim 1 or 2, wherein the isocyanate compound contains the second isocyanate compound. The absolute value of the difference between the first tensile elongation at break of the inner layer under the conditions of 0 ° C. and 500 mm / min and the second tensile elongation at break of the multilayer tube under the conditions of 0 ° C. and 500 mm / min is The multilayer tube according to any one of claims 1 to 3, which is 30% or less. Claim 1 in which the result of the adhesion test is Category 0 or Category 1 when the adhesion test between the inner layer and the outer layer is performed by the cross-cut method in accordance with JIS K5600-5-6. 4. The multi-layer tube according to any one of 4 to 4. The multi-layer pipe according to any one of claims 1 to 5, which is a joint.

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