JP2022137147A - Pipe for air-conditioning drain and manufacturing method of pipe for air-conditioning drain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe for an air-conditioning drain having resistance to impact shock from the external.

SOLUTION: A pipe for an air-conditioning drain includes: a cylindrical foamed layer including vinyl chloride-based resin (B); and a non-foamed outer layer disposed on an outer surface of the foamed layer and including a vinyl chloride-based resin (A), wherein an expansion ratio of the foamed layer is 3.5 times or more, and the vinyl chloride-based resin (A) is a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerizing the elastomer resin to the vinyl chloride resin.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an air conditioning drain pipe.

Air-conditioning drain pipes are required to have excellent heat insulating properties. Such an air conditioning drain pipe contains a vinyl chloride resin and has a foam layer, a non-foam inner layer laminated on the inner surface of the foam layer, and a non-foam outer layer laminated on the outer surface of the foam layer. Layered tubes are preferably used.

Patent Literature 1 proposes a method of manufacturing a pipe with a three-layer structure by forming a coating layer by cooling the outer surface of a thermoplastic resin composition for a foam layer during extrusion molding.

JP 2015-96314 A

However, the tube obtained by the method of Patent Literature 1 has a problem that it is vulnerable to impact from the outside and is easily broken.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air-conditioning drain pipe that is resistant to impact from the outside.

The present invention has the following aspects.
[1] A cylindrical foam layer containing a vinyl chloride resin (B);
An air conditioning drain pipe provided on the outer surface of the foamed layer and comprising a non-foamed outer layer containing a vinyl chloride resin (A),
The expansion ratio of the foamed layer is 3.5 times or more,
An air-conditioning drain pipe, wherein the vinyl chloride-based resin (A) is a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft-polymerizing an elastomer resin to a vinyl chloride resin.
[2] The air conditioning drain pipe according to [1], wherein the vinyl chloride resin contained in the vinyl chloride resin (A) has an average degree of polymerization of 800 or more and 1000 or less.

According to the present invention, it is possible to provide an air-conditioning drain pipe that is resistant to impact from the outside.

1 is a cross-sectional view showing an example of an air-conditioning drain pipe of the present invention; FIG. 1 is a front view showing an apparatus for measuring fusion bonding strength; FIG. FIG. 4 is a cross-sectional view showing another example of the air-conditioning drain pipe of the present invention; FIG. 2 is a plan view of a manufacturing apparatus for manufacturing an air-conditioning drain pipe; 1 is a front view of a manufacturing apparatus for manufacturing an air-conditioning drain pipe; FIG. FIG. 2 is a configuration diagram showing a mold and a tube for forming the outer surface of the pipe used in the air conditioning drain pipe manufacturing apparatus; FIG. 11 is a plan view of a manufacturing apparatus for manufacturing an air-conditioning drain pipe of Comparative Example 2; FIG. 11 is a front view of a manufacturing apparatus for manufacturing an air-conditioning drain pipe of Comparative Example 2; FIG. 10 is a configuration diagram showing a mold, a pipe outer surface adjustment device, and a cooling device used in the air conditioning drain pipe manufacturing apparatus of Comparative Example 2; FIG. 10 is an enlarged view of a portion A in FIG. 9;

≪Air conditioning drain pipe≫
The air-conditioning drain pipe of the present invention comprises a tubular foamed layer containing a vinyl chloride resin (B), and a non-foamed outer layer provided on the outer surface of the foamed layer and containing the vinyl chloride resin (A). .
FIG. 1 is a cross-sectional view showing an example of an air-conditioning drain pipe of the present invention. As shown in FIG. 1 , the air conditioning drain pipe 10 includes a tubular foam layer 2 and a non-foam outer layer 3 laminated on the outer surface of the foam layer 2 .

The air-conditioning drain pipe 10 is cut to an arbitrary length at the construction site, and connected by inserting the end of the air-conditioning drain pipe 10 into a receptacle of a pipe joint (not shown) such as a socket, elbow, or cheese. be. The air-conditioning drain pipe 10 and the pipe joint constitute an air-conditioning drain pipe. Therefore, inside the socket of the pipe joint, the foam layer 2 and the non-foam outer layer 3 are exposed on the end surface (cut surface) of the air-conditioning drain pipe 10 .
In the air-conditioning drain pipe 10, the foam layer 2 has a high closed cell ratio, and the drain water flowing down inside the pipe does not easily permeate. It is not necessary to provide an annular elastic body inside the pipe joint.

The outer diameter of the air-conditioning drain pipe 10 is preferably, for example, 32 mm or more and 100 mm or less. The inner diameter of the air-conditioning drain pipe 10 is preferably, for example, 19 mm or more and 80 mm or less. The thickness of the air-conditioning drain pipe 10 including the foam layer 2 and the non-foam outer layer 3 is preferably, for example, 6 mm or more and 10 mm or less.

The longitudinal elastic modulus of the air-conditioning drain pipe 10 is preferably 400 MPa or more and 1500 MPa or less, more preferably 500 MPa or more and 1300 MPa or less, and even more preferably 600 MPa or more and 1000 MPa or less.
By setting the modulus of longitudinal elasticity within the above numerical range, when the air-conditioning drain pipe 10 receives an external force, the air-conditioning drain pipe 10 flexibly follows the external force while suppressing deformation such as bending and elongation and breaks. can prevent it from being done.
The longitudinal elastic modulus is also called longitudinal elastic modulus or Young's modulus, and is obtained from tensile stress and tensile strain obtained by a tensile test according to JIS K 7161-1:2014.
The modulus of longitudinal elasticity can be adjusted by adjusting the degree of polymerization of the vinyl chloride resin, the expansion ratio of the foam layer 2, the thickness of each of the foam layer 2 and the non-foam outer layer 3, and the like.

<Non-foaming outer layer>
The non-foamed outer layer 3 is a non-foamed layer containing vinyl chloride resin (A). Here, the non-foaming layer refers to a layer in which the vinyl chloride resin does not contain a foaming agent and no air bubbles are formed due to the expansion of the foaming agent.
The vinyl chloride resin (A) may be a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerization of a vinyl chloride resin to an elastomer resin.
The vinyl chloride resin may be polyvinyl chloride or a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. Other monomers copolymerizable with the vinyl chloride monomer include, for example, ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. and other monomers. These may be used alone, or two or more of them may be used in combination.
Examples of elastomer resins include chlorinated polyethylene (CPE), methyl methacrylate-butadiene-styrene copolymer (MBS), and alkyl (meth)acrylate resins.
The mass ratio of vinyl chloride resin: elastomer resin is preferably 100:4 to 100:10.

As the alkyl (meth)acrylate resin, it is preferable to use an alkyl (meth)acrylate monomer whose homopolymer has a glass transition temperature of less than -20°C. Examples of the alkyl (meth)acrylate monomers include ethyl acrylate, n-propyl acrylate, isobutyl acrylate, n-butyl acrylate, sec-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl (meth) acrylate. , isooctyl acrylate, n-decyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl acrylate, 2-acryloyloxyethyl succinic acid and the like. These may be used alone or in combination of two or more.

The form and structure of the alkyl (meth)acrylate resin are not particularly limited. , it is possible to give different functions to the core portion and the shell portion, which is preferable. As the alkyl (meth)acrylate monomer used in the core portion, it is preferable to use one having a low glass transition temperature in consideration of improving the impact resistance of the molded article. For example, 2-ethylhexyl acrylate is preferably used. For the shell portion, it is preferable to use n-butyl acrylate from the viewpoint of improving the handleability of the alkyl (meth)acrylate resin.

As the alkyl (meth)acrylate resin, 0.01 to 15 parts by weight of a polyfunctional monomer may be added to 100 parts by weight of the alkyl (meth)acrylate monomer. If the amount of the polyfunctional monomer added is less than 0.01 parts by weight with respect to 100 parts by weight of the alkyl (meth)acrylate monomer, the durability of the finally obtained molded article is reduced, exceeding, the impact resistance decreases.

The polyfunctional monomer is not particularly limited as long as it is copolymerizable with the alkyl (meth)acrylate monomer. Examples include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,6 - Polyfunctional acrylates such as hexanediol di(meth)acrylate, trimethylolpropane di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; multifunctional allyl compounds such as diallyl phthalate, diallyl maleate, and triallyl isocyanurate ; and unsaturated compounds such as butadiene. These may be used alone or in combination of two or more.

The method for obtaining the alkyl (meth)acrylate resin is not particularly limited, and examples thereof include an emulsion polymerization method and a suspension polymerization method. Considering the development of impact resistance, the emulsion polymerization method is preferred. In the emulsion polymerization method, an emulsifying dispersant is added for the purpose of improving the dispersion stability of the alkyl (meth)acrylate monomer in the emulsion and performing the polymerization efficiently. The emulsifying dispersant is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, partially saponified polyvinyl alcohol, cellulose dispersants, and gelatin.

Moreover, a polymerization initiator is used in the emulsion polymerization method. The polymerization initiator is not particularly limited, and examples include potassium persulfate, ammonium persulfate, water-soluble polymerization initiators of hydrogen peroxide, organic peroxides such as benzoyl peroxide and lauroyl peroxide, and azobisisobutyronitrile. azo initiators such as Furthermore, if necessary, a pH adjuster, an antioxidant, etc. may be added.

The emulsion polymerization method is not particularly limited, and may be, for example, a batch polymerization method, a monomer dropping method, an emulsion dropping method, or the like, depending on the method of adding the monomer. In the batch polymerization method, for example, in a jacketed polymerization reactor, pure water, an emulsifying dispersant, a polymerization initiator and a mixed monomer [the alkyl (meth)acrylate monomer + the polyfunctional monomer added as necessary] are added. are added all at once, and under the conditions of oxygen removal and pressurization by a nitrogen stream, the mixture is sufficiently emulsified by stirring, and then the inside of the vessel is heated with a jacket for polymerization.

In the monomer dropping method, for example, pure water, an emulsifying dispersant, and a polymerization initiator are placed in a jacketed polymerization reactor, and the interior of the reactor is first heated with a jacket under the conditions of oxygen removal and pressurization under a nitrogen stream. 2) Gradual polymerization is carried out by dropping the above-mentioned mixed monomer by a constant amount.

In the emulsion dropping method, for example, the mixed monomer, emulsifying dispersant, and pure water are sufficiently emulsified by stirring to prepare an emulsified monomer in advance, then pure water and a polymerization initiator are put into a jacketed polymerization reactor, and nitrogen is added. In this method, the inside of the vessel is first heated with a jacket under the conditions of oxygen removal and pressurization under an air stream, and then the above-mentioned emulsified monomer is added dropwise at a time to polymerize.

Even when the alkyl (meth)acrylate resin has a core-shell structure, the formation method is not particularly limited. The polyfunctional monomer added according to the above], a polymerization initiator is added to an emulsified monomer prepared from pure water and an emulsifier to carry out a polymerization reaction to form the resin particles of the core portion, and then the mixture constituting the shell portion A method of adding an emulsified monomer prepared from a monomer [the above-mentioned alkyl (meth)acrylate monomer + the above-mentioned polyfunctional monomer added as necessary], pure water and an emulsifier, and graft-copolymerizing the shell portion to the above-mentioned core portion, and the like. are mentioned.

In the alkyl (meth)acrylate resin thus obtained, the surface of the core portion is three-dimensionally covered with the shell portion, and the copolymer constituting the shell portion and the copolymer constituting the core portion are partially covalently bonded, and the shell portion forms a three-dimensional crosslinked structure.
In the above method, the graft copolymerization of the shell portion may be carried out continuously in the same polymerization step as that of the core portion.

The ratio of the core part to the shell part can be adjusted by adjusting the ratio of the mixed monomers forming the core part and the mixed monomers forming the shell part in the emulsion polymerization method.

As the vinyl chloride-based resin (A), the alkyl (meth)acrylate resin obtained by the above method is used, and this alkyl (meth)acrylate resin is added with vinyl chloride, or vinyl chloride and vinyl chloride and other copolymers. A vinyl chloride resin (A) obtained by graft-copolymerizing a monomer of (A) is preferably used.

The method for obtaining the vinyl chloride resin is not particularly limited, and examples thereof include an emulsion polymerization method and a suspension polymerization method. Among them, the suspension polymerization method is preferable. In the suspension polymerization method, the dispersion stability of the alkyl (meth)acrylate resin is improved, and the graft copolymerization of vinyl chloride or a mixture of vinyl chloride and other monomers copolymerizable with vinyl chloride is efficiently performed. A dispersant and an oil-soluble polymerization initiator are used for the purpose of

The dispersant is not particularly limited, and examples thereof include methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, polyvinyl alcohol, partially saponified polyvinyl acetate, gelatin, polyvinylpyrrolidone, starch-maleic anhydride-styrene copolymer, and the like. These may be used alone or in combination of two or more.

As the oil-soluble polymerization initiator, a radical polymerization initiator is preferably used because it is advantageous for graft copolymerization. Polymerization initiators used in the present invention include, for example, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, t-butyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, isobutyryl peroxide, α,α' Bis(neodecanoylperoxy)diisopropylbenzene, organic peroxides such as 1,1,3,3-tetramethylbutyl peroxyneodecanoate; 2,2-azobis-2,4-dimethyl and azo compounds such as valeronitrile.

In the suspension polymerization method described above, a pH adjuster, an antioxidant, and the like may be added as necessary.

In the suspension polymerization method, specifically, for example, pure water, the alkyl (meth)acrylate resin, a dispersant, an oil-soluble polymerization initiator, and, if necessary, a reaction vessel equipped with a stirrer and a jacket. If necessary, add a polymerization modifier, then evacuate the air from the polymerization vessel with a vacuum pump, then add vinyl chloride and, if necessary, other vinyl monomers under stirring conditions, and then add the reaction vessel. The inside is heated by a jacket to carry out graft copolymerization of vinyl chloride.

Since the graft copolymerization of vinyl chloride is an exothermic reaction, the temperature in the reaction vessel can be controlled by changing the jacket temperature. After completion of the reaction, unreacted vinyl chloride is removed to form a slurry, and the slurry is dehydrated and dried to produce a vinyl chloride resin. The vinyl chloride resin produced by the above production method is obtained by graft-copolymerizing the vinyl chloride resin (A) onto the alkyl (meth)acrylate resin, so that the vinyl chloride resin molded article has excellent impact resistance. can be molded.

The non-foamed outer layer 3 may contain a thermoplastic resin other than the vinyl chloride resin (A). Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin and acrylic resin. These may be used alone, or two or more of them may be used in combination.

The weight average molecular weight of the vinyl chloride resin (A) is preferably 37,500 or more and 81,000 or less, more preferably 50,000 or more and 81,000 or less.
The mass average molecular weight is a value measured by gel permeation chromatography using polyethylene glycol as a standard substance.
The average degree of polymerization of the vinyl chloride resin in the vinyl chloride resin (A) is preferably 600 or more and 1300 or less, more preferably 800 or more and 1300 or less, and even more preferably 800 or more and 1000 or less.
The average degree of polymerization can be calculated by dividing the weight average molecular weight by the molecular weight of chloroethylene.

The thickness of the non-foamed outer layer 3 is preferably 0.6 mm or more and 1.5 mm or less, more preferably 1.0 mm or more and 1.3 mm or less. By making the thickness of the non-foamed outer layer 3 equal to or greater than the above lower limit, it can be strengthened against impact from the outside. By making the thickness of the non-foamed outer layer 3 equal to or less than the above upper limit, the weight of the air-conditioning drain pipe 10 can be reduced. Moreover, since the thickness of the foam layer 2 can be increased, the air-conditioning drain pipe 10 can be made excellent in heat insulation.
In the case of strengthening by impact from the outside, the thickness of the non-foamed outer layer 3 is preferably 1.0 mm or more and 5.0 mm or less, more preferably 1.5 mm or more and 3.5 mm or less.

The non-foamed outer layer 3 may contain a pigment. Appearance can be improved by containing a pigment.

<Foam layer>
The foam layer 2 is formed by foaming a resin containing a vinyl chloride resin (B) and a thermoplastic resin composition for a foam layer containing a foaming agent.
The vinyl chloride resin (B) may be a vinyl chloride resin, a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerization of a vinyl chloride resin to an elastomer resin.
The vinyl chloride resin may be polyvinyl chloride or a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. Other monomers copolymerizable with the vinyl chloride monomer include, for example, ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. and other monomers. These may be used alone, or two or more of them may be used in combination.
Examples of elastomer resins include chlorinated polyethylene (CPE), methyl methacrylate-butadiene-styrene copolymer (MBS), and alkyl (meth)acrylate resins.
The vinyl chloride resin (B) may be the same as or different from the vinyl chloride resin (A).
The thickness of the foam layer 2 is preferably 4.0 mm or more and 10 mm or less.

The foam layer 2 may contain a thermoplastic resin other than the vinyl chloride resin (B). Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin and acrylic resin. These may be used alone, or two or more of them may be used in combination.

The weight average molecular weight of the vinyl chloride resin (B) is preferably 37,500 or more and 62,500 or less, more preferably 44,000 or more and 56,000 or less.
The average degree of polymerization of the vinyl chloride resin in the vinyl chloride resin (B) is preferably 600 or more and 1000 or less, more preferably 700 or more and 900 or less.

As the foaming agent, either a volatile foaming agent or a decomposable foaming agent may be used.
Volatile foaming agents include, for example, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers, ketones and the like. Of these, aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), and alicyclic hydrocarbons include cyclopentane, cyclohexane, and the like. mentioned. Examples of halogenated hydrocarbons include one or more of halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane, and difluoroethane. Examples of ethers include dimethyl ether and diethyl ether, and examples of ketones include acetone and methyl ethyl ketone.
Examples of decomposition-type foaming agents include inorganic foaming agents such as sodium bicarbonate (sodium hydrogen carbonate), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds, sodium borohydride, azodicarbonamide, and barium azodicarboxylate. and dinitrosopentamethylenetetramine.
Also, a thermally expandable capsule in which the above hydrocarbon is encapsulated in a thermoplastic resin may be used.
In addition, gases such as carbon dioxide, nitrogen, and air may be used as foaming agents.
These may be used alone, or two or more of them may be used in combination.

The foam layer 2 may contain known stabilizers such as lead compounds (lead-based stabilizers), CaZn compounds (CaZn-based stabilizers), and tin compounds (tin-based stabilizers). In particular, the inclusion of a stabilizer containing a tin compound facilitates enhancing the thermal stability of the resin. Mercapto-based, laurate-based, and malate-based tin compounds are preferred.
The presence and content of these compounds are confirmed by inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), gas chromatograph mass spectrometry (GC-MS), and the like. be able to. In the case of ICP-AES, it can be measured according to EN ISO17353:2004.
The foam layer 2 may contain a lubricant. By containing a lubricant, it becomes easier to maintain the lubricity on metal surfaces and the lubricity between resins. Ester-based, polyethylene-based, and polyethylene oxide-based lubricants are preferable as lubricants.

The expansion ratio of the foam layer 2 is 3.5 times or more, preferably 4.0 times or more. Moreover, 8.0 times or less is preferable and 6.0 times or less is more preferable.
By setting the expansion ratio within the above range, it is possible to achieve both heat insulating properties and pipe strength. Further, by setting the foaming ratio within the above range, the weight of the air-conditioning drain pipe 10 can be reduced.
The expansion ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, manufacturing conditions, and the like.
The foaming ratio can be measured by the following method.
[Method for measuring expansion ratio]
10 mm or more in the circumferential direction and 50 mm in the axial direction are cut from the air-conditioning drain pipe 10, the non-foamed outer layer 3 is cut with a milling machine, and only the foamed layer 2 is processed into a plate with a length of about 50 mm to obtain a test piece. . In addition, four test pieces shall be prepared centering on points which are evenly divided into four in the inner circumferential direction.
According to JIS K 7112:1999, the apparent density of the test piece is determined to three digits after the decimal point at 23° C.±2° C. with a water displacement type specific gravity meter, and the foaming ratio is calculated by the following formula (1).
m=γc/γ (1)
[In formula (1), m is the expansion ratio, γ is the apparent density (g/cm ³ ) of the foam layer 2, and γc is the density (g/cm ³ ) of the foam layer 2 when not foamed. . ]

The closed cell ratio of the foam layer 2 is preferably 20% or more, more preferably 45% or more, still more preferably 60% or more, and particularly preferably 80% or more. The upper limit of the closed cell ratio is not particularly limited, and is practically 95% or less, and may be 100% or 90% or less.
By setting the closed cell ratio within the above range, it is possible to improve heat insulation and prevent water from permeating into the foam layer 2 . Further, when the closed cell ratio of the foamed layer 2 is within the above numerical range, even if the thickness of the non-foamed outer layer 3 described later is reduced, it is difficult for water to permeate from the outside, and the heat insulating property is less likely to deteriorate.
The closed cell content can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.
In addition, a closed-cell rate can be measured with the following method.
[Measurement method of closed cell ratio]
The air-conditioning drain pipe 10 is cut to a length of about 30 mm, cut in the circumferential direction so as to have a circumferential length of about 20 mm, and the non-foamed outer layer 3 is removed with an NT cutter to obtain a test piece.
According to JIS K 7138, measure the volume with an air comparison type hydrometer at 23 ° C. ± 2 ° C., according to JIS K 7112: 1999, measure the volume obtained with a water displacement type hydrometer at 23 ° C. ± 2 ° C., (2) measures the closed cell ratio.
Cc=(Va/Vaq)×100 (2)
[In formula (2), Cc is the closed cell ratio (%), Va is the air comparison formula volume (cm ³ ), and Vaq is the water displacement method volume (cm ³ ). ]

The average cell diameter of the foam layer 2 is preferably 30 μm to 1000 μm, more preferably 40 μm to 700 μm, even more preferably 50 μm to 400 μm, and particularly preferably 50 μm to 250 μm.
By setting the average cell diameter within the above range, it is possible to improve heat insulation and prevent water from permeating into the foam layer 2 . Even if the cells are not completely closed cells (closed cell ratio is 100%) and the cell walls are partially connected and water can permeate, the average cell diameter is within the above range and the closed cell ratio is Within the above range, water does not permeate deep into the foam layer 2, and the heat insulation performance does not pose a problem in practical use.
The average cell diameter can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.
Incidentally, the average bubble diameter can be measured by the following method.
[Method for measuring average bubble diameter]
Image taken by cutting the air conditioning drain pipe in the circumferential direction and photographing the annular end face of the cut air conditioning drain pipe in accordance with JIS K 6400-1 with a scanning electron microscope (SEM) at a magnification of 20. 8 straight lines of 3.6 cm (corresponding to the length of 1800 μm in the actual pipe cross section) are drawn above (2 in the vertical direction (thickness direction of the pipe cross section) and 2 in the horizontal direction (circumferential direction of the pipe cross section). 2 at an angle of 45° to the horizontal direction, and 2 at an angle of 135° to the horizontal direction). Then, the average value of the bubble diameters obtained from the eight straight lines is defined as the average bubble diameter.

<Non-foaming inner layer>
As shown in FIG. 3, the air conditioning drain pipe of the present invention may have a non-foamed inner layer 1 which is a non-foamed layer provided on the inner surface of the foamed layer 2 and containing vinyl chloride resin (C). . The vinyl chloride resin (C) may be a vinyl chloride resin, a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerizing a vinyl chloride resin to an elastomer resin.
The vinyl chloride resin may be polyvinyl chloride, or may be a vinyl chloride monomer and another copolymer that can be copolymerized with the vinyl chloride monomer. Other monomers copolymerizable with the vinyl chloride monomer include, for example, ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. and other monomers. These may be used alone, or two or more of them may be used in combination.
Examples of elastomer resins include chlorinated polyethylene (CPE), methyl methacrylate-butadiene-styrene copolymer (MBS), and alkyl (meth)acrylate resins.
The mass ratio of vinyl chloride resin: elastomer resin is preferably 100:4 to 100:10.
The vinyl chloride resin (C) may be the same as or different from the vinyl chloride resin (A).

The non-foamed inner layer 1 may contain a thermoplastic resin other than the vinyl chloride resin (C). Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin and acrylic resin. These may be used alone, or two or more of them may be used in combination.

The weight average molecular weight of the vinyl chloride resin (C) is preferably 37,500 or more and 62,500 or less, more preferably 50,000 or more and 62,500 or less.
The average degree of polymerization of the vinyl chloride resin in the vinyl chloride resin (C) is preferably 800 or more and 1000 or less.

The thickness of the non-foamed inner layer 1 is preferably 1.0 mm or more and 5.0 mm or less, more preferably 1.5 mm or more and 3.5 mm or less. By setting the thickness of the non-foamed inner layer 1 within the above numerical range, there is no possibility that drain water flowing inside penetrates into the foamed layer 2, and the air-conditioning drain pipe 10' having excellent heat insulation can be obtained.
On the other hand, when the closed cell ratio of the foam layer 2 is high, the thickness of the non-foam inner layer 1 may be 0.6 mm or more and 1.5 mm or less because the foam layer 2 itself prevents permeation of drain water. The tube 10' can be made lighter. Moreover, since the thickness of the foam layer 2 can be increased, the air-conditioning drain pipe 10' can be made excellent in heat insulation.

The fusion strength between the foamed layer 2 and the non-foamed inner layer 1 is preferably 1.5 MPa or higher, more preferably 2.0 MPa or higher.
By setting the fusion bond strength within the above range, it is possible to prevent separation between the foam layer 2 and the non-foam inner layer 1 .
The fusion bonding strength can be adjusted by the type or amount of resin, the type or amount of foaming agent, manufacturing conditions, and the like.
Note that the fusion bond strength can be measured by the following method.
[Method for measuring fusion bonding strength]
A test piece is obtained by cutting the air-conditioning drain pipe 10' into a 20 mm tubular shape along the pipe axis.
Under the conditions of a temperature of 23° C.±2° C. and a humidity of normal humidity (45 to 85%), a test piece 43 is set in a punching jig 41 of a universal testing machine 40 shown in FIG. , Compress at a rate of 10 mm/min ± 2 mm/min per minute in a direction perpendicular to the tube axis, and obtain the maximum load when the fused surfaces of the non-foamed inner layer 1 and the foamed layer 2 separate, and use the following formula ( 3) and (4) calculate the fusion bond strength.
F=W/S (3)
S=3.14×d×L (4)
[In formulas (3) and (4), F is the fusion bond strength (MPa), W is the maximum load (N), S is the fusion bond area (cm ² ), and d is the non-foamed inner layer average is the outer diameter (cm), and L is the test piece length (cm). ]

<<Manufacturing method for air conditioning drain pipe>>
4 and 5 are general configuration diagrams of a manufacturing apparatus 20 for manufacturing an air-conditioning drain pipe 10' having a three-layer structure. The manufacturing apparatus 20 includes an inner/outer layer extruder 11 , a foamed layer extruder 12 , a mold 13 , a cooling water tank 15 , a take-up machine 16 and a cutting machine 17 . A mold 13 is connected to the inner/outer layer extruder 11 and the foamed layer extruder 12 , and a cooling water tank 15 is connected to the mold 13 . A take-up machine 16 is connected to the cooling water tank 15 , and a cutting machine 17 is connected to the take-up machine 16 . Furthermore, as shown in FIGS. 4 and 5, a gas cylinder 18 and a metering pump 19 may be connected to the foamed layer extruder 12 .
A gas cylinder 18 and a metering pump 19 supply a gaseous foaming agent from a vent hole of the foam layer extruder 12 .
The inner and outer layer extruder 11 melt-kneads the thermoplastic resin composition for the non-foamed layer forming the non-foamed inner layer 1 and the non-foamed outer layer 3 and extrudes it into the mold 13 .
The foam layer extruder 12 melts and kneads the thermoplastic resin composition for forming the foam layer 2 and extrudes it into the mold 13 .
The mold 13 is made from the thermoplastic resin composition for the non-foamed layer injected from the inner and outer layer extruder 11 and the thermoplastic resin composition for the foamed layer injected from the foamed layer extruder 12, and an uncured three-layer structure. The air conditioning drain pipe 100' is molded.
Attached to the cooling water tank 15 is a pipe outer surface forming tube 14 for forming the uncured air-conditioning drain pipe 100′ into a predetermined size. ' is cooled while it is in contact with the tube 14 for forming the outer surface of the tube.
The take-up machine 16 receives the air-conditioning drain pipe 10 ′ cooled by the cooling water tank 15 .
The cutting machine 17 cuts the air-conditioning drain pipe 10' sent from the take-up machine 16 to a predetermined length.

First, the thermoplastic resin composition for the non-foamed layer is supplied to the inner and outer layer extruder 11 and melt-kneaded. Separately, the thermoplastic resin composition for the foam layer is supplied to the foam layer extruder 12 and melt-kneaded.
At this time, when gas is used as a foaming agent, the gas in the gas cylinder 18 is supplied from the vent hole by the pumping operation of the metering pump 19 while the thermoplastic resin composition for the foam layer is being melted and kneaded. When a solid or liquid foaming agent is used, the foaming agent may be blended in advance with the thermoplastic resin composition for the foam layer.

Then, as shown in FIG. 6, a non-foamed layer thermoplastic resin composition 21 melt-kneaded by the inner and outer layer extruder 11 and a foamed layer thermoplastic resin composition 22 melt-kneaded by the foamed layer extruder 12. are injected into the mold 13 and merged inside the mold 13 to form an uncured air-conditioning drain pipe 100' having a three-layer structure. The uncured air-conditioning drain pipe 100 ′ includes a non-foamed thermoplastic resin layer 31 formed from the non-foamed layer thermoplastic resin composition 21 and a non-foamed thermoplastic layer between the non-foamed inner layer and the non-foamed outer layer. and a foamed thermoplastic resin layer 32 formed from the resin composition 22 .

Further, when the uncured air-conditioning drain pipe 100 ′ having a three-layer structure is extruded from the mold 13 , the resin of the foamed thermoplastic resin layer 32 foams. The uncured air-conditioning drain pipe 100′ is inserted into the tube outer surface forming tube 14, and the uncured air-conditioning drain pipe 100′ is molded into a predetermined size and cooled in the cooling water tank 15 to form the air-conditioning drain pipe. 10'. Further, the cooled and molded air-conditioning drain pipe 10' is handed over to a take-up machine 16, sent to a cutting machine 17, and cut to a predetermined length by the cutting machine 17. - 特許庁

The temperature for molding with the mold 13 is preferably 140° C. or higher and 200° C. or lower, and more preferably 160° C. or higher and 190° C. or lower.
The molding time is preferably 10 minutes or more and 30 minutes or less, more preferably 10 minutes or more and 20 minutes or less.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples.

The components in the table are explained below.
The content of each component in the table represents parts by mass based on 100 parts by mass of polyvinyl chloride in the foam layer.
<Vinyl chloride resin (B)>
· B-1: Polyvinyl chloride (degree of polymerization 800, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name "TS-800E").
<Blowing agent>
· D-1: Baking soda (trade name “Cellbon SC-855” manufactured by Eiwa Kasei Kogyo Co., Ltd.).
- D-2: Azodicarbonamide (manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name "Vinihole AC#3").
<Vinyl chloride resins (A) and (C)>
・ A-1: MBS (manufactured by Kaneka Corporation, product name “B-564”) is added to 100 parts by mass of polyvinyl chloride (degree of polymerization: 1000, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., product name “TS-1000R”). and 3 parts by mass of CPE (manufactured by Showa Denko Co., Ltd., trade name “Eraslen 351A”).
· A-2: MBS (manufactured by Kaneka Corporation, trade name "B-564") is added to 100 parts by mass of polyvinyl chloride (degree of polymerization: 1000, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name "TS-1000R"). 5 parts by mass and 3.5 parts by mass of CPE (manufactured by Showa Denko Co., Ltd., trade name "Eraslen 351A").
A-3: MBS (manufactured by Kaneka, product name “B-564”) is added to 100 parts by mass of polyvinyl chloride (degree of polymerization: 1000, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., product name “TS-1000R”). 1.5 parts by mass of CPE (manufactured by Showa Denko Co., Ltd., trade name "Eraslen 351A").
A-4: Graft polymer of vinyl chloride and alkyl (meth)acrylate (degree of polymerization: 1200, product name: "AG-64T" manufactured by Tokuyama Sekisui Kogyo Co., Ltd., elastomer content: 5.3% by mass).
· A-5: Polyvinyl chloride (degree of polymerization: 1000, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name “TS-1000R”).
A-6: Polyvinyl chloride (degree of polymerization 800, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name "TS-800E").

(Example 1)
100 parts by mass of polyvinyl chloride B-1, 2 parts by mass of a tin-based stabilizer (trade name “STX-80” manufactured by Daikyo Kasei Kogyo Co., Ltd.), and 2.2 parts by mass of foaming agent D-1 are mixed. to prepare a thermoplastic resin composition for a foam layer.
Vinyl chloride resin A-1 was prepared as described above, and 100 parts by mass of vinyl chloride resin A-1 and 2 parts by mass of a tin-based stabilizer (manufactured by Daikyo Kasei Kogyo Co., Ltd., trade name "STX-80") were mixed to prepare a thermoplastic resin composition for the inner layer and the outer layer.
These compositions were subjected to an inner and outer layer extruder 11, a foamed layer extruder 12, a mold 13, a cooling water tank 15 fitted with a tube for forming the outer surface of a tube 14, a take-up machine 16, and a cutting machine 17 shown in FIGS. Extrusion was performed using a manufacturing apparatus consisting of
Specifically, the thermoplastic resin composition for the non-foamed layer was kneaded at 180° C. by the inner and outer layer extruder 11 and injected into the mold 13 at an extrusion rate of 45 kg/h. Further, the foam layer thermoplastic resin composition was kneaded at 170° C. by the foam layer extruder 12 and injected into the mold 13 at 25 kg/h. As the mold 13, a mold having a product outer diameter of 89 mm and an inner diameter of 77 mm was used. The composition discharged from the mold 13 is inserted into the tube 14 for forming the outer surface of the tube, cooled in the cooling water tank 15, taken by the take-up machine 16, cut into a predetermined length by the cutter 17, and cut into three pieces. A layered air conditioning drain pipe was obtained. The thickness of the non-foamed outer layer was measured to be 1.0 mm.

(Examples 2 to 5, Comparative Examples 1 and 3)
A three-layer air-conditioning drain pipe was obtained in the same manner as in Example 1, except that the components were changed to those shown in Tables 1 and 2. The thickness of the non-foamed outer layer was measured to be 1.0 mm.

(Comparative example 2)
A thermoplastic resin composition for a foam layer was prepared by mixing 100 parts by mass of polyvinyl chloride B-1 and 2.2 parts by mass of foaming agent D-1.
Vinyl chloride resin A-6 was used as the thermoplastic resin composition for the inner and outer layers.
An air-conditioning drain pipe was manufactured using an air-conditioning drain pipe manufacturing apparatus 500 shown in FIGS.
7 and 8, the manufacturing apparatus 500 includes a first extruder 530, a second extruder 540, a mold 550, a tube outer surface conditioning device 560, a cooling device 570, a take-up device 580, and a cutting device 590. The first extruder 530 and the second extruder 540 are connected to a mold 550, the mold 550 is connected to a pipe outer surface conditioning device 560, the pipe outer surface conditioning device 560 is connected to a cooling device 570, and the cooling device 570 is A take-up machine 580 is connected, and the take-up machine 580 is connected to a cutting machine 590 . The thermoplastic resin composition for the foam layer was kneaded at 170° C. by the first extruder 530 and injected into the mold 550 at an extrusion rate of 25 kg/h. Further, the thermoplastic resin composition for the non-foamed layer was kneaded at 180° C. by the second extruder 540 and injected into the mold 550 at an extrusion rate of 45 kg/h. As the mold 550, a mold having a product outer diameter of 89 mm and an inner diameter of 77 mm was used. The mold 550 has a first mold 551 and a crosshead die 552, as shown in FIG. The composition ejected from the mold 550 is brought into contact with the inside of the pipe outer surface conditioning device 560 . At this time, the temperature of the outer surface is lowered, and as shown in FIG. 10, a coating layer 230 is formed as the outermost layer. After being cooled in the cooling device 570 and taken up by the take-up machine 580, it is cut to a predetermined length by the cutting machine 590, and has a three-layer structure for air conditioning drains consisting of a non-foamed inner layer 210, a foamed layer 220, and a coating layer 230. got a tube. When the thickness of the coating layer was measured, it was 1.0 mm.

The foaming ratio, impact resistance, fusion bond strength, pencil hardness, and longitudinal elastic modulus of the obtained air-conditioning drain pipe were measured according to the following procedures.

[Measurement of expansion ratio]
A test piece is obtained by cutting out a section of 10 mm or more in the circumferential direction and 50 mm in the axial direction from an air conditioning drain pipe, cutting the non-foamed inner layer and the non-foamed outer layer with a milling machine, and processing only the foamed layer into a plate with a length of about 50 mm. did. In addition, four test pieces were prepared centering on points that were evenly divided into four in the inner circumferential direction.
According to JIS K 7112:1999, the apparent density of the test piece was determined to three digits after the decimal point at 23° C.±2° C. with a water displacement type specific gravity meter, and the foaming ratio was calculated by the following formula (1).
m=γc/γ (1)
[In formula (1), m is the foaming ratio, γ is the apparent density (g/cm ³ ) of the foamed layer, and γc is the density (g/cm ³ ) of the foamed layer when not foamed. ]
The obtained results are shown in Tables 1 and 2.

[Measurement of impact resistance]
A Phillips screwdriver (100 g) was vertically dropped onto the air-conditioning drain pipe, and the height at which the air-conditioning drain pipe cracked was measured.
Specifically, a Phillips screwdriver was vertically dropped from a predetermined height onto the air-conditioning drain pipe, and water pressure of 0.06 MPa was applied to the inside of the air-conditioning drain pipe for 1 minute to check for water leakage. The height from which the Phillips screwdriver was dropped was measured when water leakage was confirmed.
The obtained results are shown in Tables 1 and 2.

[Measurement of welding strength]
A test piece was obtained by cutting an air-conditioning drain pipe into a 20 mm tubular shape along the pipe axis.
Under conditions of a temperature of 23° C.±2° C. and normal humidity (45 to 85%), a test piece 43 is set in a punching jig 41 of a universal testing machine 40 shown in FIG. Compress at a rate of 10 mm/min ± 2 mm/min in a direction perpendicular to the pipe axis, and obtain the maximum load when the fused surface between the non-foamed inner layer and the foamed layer separates, using the following formula (3) and The fusion bond strength was calculated in (4).
F=W/S (3)
S=3.14×d×L (4)
[In formulas (3) and (4), F is the fusion bond strength (MPa), W is the maximum load (N), S is the fusion bond area (cm ² ), and d is the non-foamed inner layer average is the outer diameter (cm), and L is the test piece length (cm). ]
The obtained results are shown in Tables 1 and 2.

[Measurement of pencil hardness]
According to JIS K 5600-5-4, the pencil hardness of the non-foamed outer layer was measured with a pencil hardness tester (manufactured by All Good Co., Ltd. 054) with a load of 750 g and a pencil angle of 45°.
The obtained results are shown in Tables 1 and 2. The symbols in the table represent pencil hardness symbols defined in JIS S6006.

[Measurement of longitudinal elastic modulus]
According to JIS K 7161-1:2014, a test piece was prepared along the tube axis and the longitudinal elastic modulus at 15°C was measured.
The obtained results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, the air-conditioning drain pipes of Examples 1 to 5 were found to be resistant to external impact.
It was found that Comparative Examples 1 to 3, in which polyvinyl chloride was used instead of the vinyl chloride resin (A), tended to crack due to external impact.

REFERENCE SIGNS LIST 1 non-foamed inner layer 2 foamed layer 3 non-foamed outer layer 10 air-conditioning drain pipe 10' air-conditioning drain pipe

The present invention has the following aspects.
[1] A cylindrical foam layer containing a vinyl chloride resin (B);
An air conditioning drain pipe provided on the inner surface of the foamed layer and comprising a non-foamed inner layer containing a vinyl chloride resin (C) ,
The expansion ratio of the foamed layer is 3.5 times or more,
The vinyl chloride resin (B) contains a vinyl chloride resin,
The vinyl chloride resin (C) is a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerization of an elastomer resin to a vinyl chloride resin ,
The average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (C) is 800 or more and 1000 or less,
The vinyl chloride resin contained in the vinyl chloride resin (B) has an average degree of polymerization of 600 or more and 1000 or less,
An air conditioning drain pipe , wherein the average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (C) is different from the average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (B) .
[2] The air conditioning drain pipe according to [1], wherein the vinyl chloride resin contained in the vinyl chloride resin (B) has an average degree of polymerization of 700 or more and 900 or less .
[3] A non-foamed outer layer provided on the outer surface of the foamed layer and containing a vinyl chloride resin (A),
The vinyl chloride resin (A) contains a vinyl chloride resin,
The air conditioning drain pipe according to [1] or [2], wherein the vinyl chloride resin contained in the vinyl chloride resin (C) is the same as the vinyl chloride resin contained in the vinyl chloride resin (A).
[4] A non-foamed outer layer provided on the outer surface of the foamed layer and containing a vinyl chloride resin (A),
The air conditioning drain pipe according to any one of [1] to [3], wherein the non-foamed outer layer has a thickness of 1.5 mm or more.
[5] A non-foamed outer layer provided on the outer surface of the foamed layer and containing a vinyl chloride resin (A),
The non-foamed outer layer has a thickness of 0.6 mm or more and 1.5 mm or less,
The air-conditioning drain pipe according to any one of [1] to [3], wherein the non-foamed inner layer has a thickness of 1.5 mm or more and 3.5 mm or less.
[6] Manufacture of an air-conditioning drain pipe comprising a cylindrical foamed layer containing a vinyl chloride resin (B) and a non-foamed inner layer provided on the inner surface of the foamed layer and containing the vinyl chloride resin (C) a method,
The vinyl chloride resin (B) contains a vinyl chloride resin,
The vinyl chloride resin (C) is a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft polymerization of an elastomer resin to a vinyl chloride resin,
The average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (C) is 800 or more and 1000 or less,
Injecting the thermoplastic resin composition for the non-foamed layer containing the vinyl chloride resin (C) from the inner and outer layer extruder into the mold,
The vinyl chloride resin contained in the vinyl chloride resin (B) has an average degree of polymerization of 600 or more and 1000 or less,
The average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (C) is different from the average degree of polymerization of the vinyl chloride resin contained in the vinyl chloride resin (B),
A thermoplastic resin composition for a foam layer containing the vinyl chloride resin (B), a foaming agent, and a stabilizer is injected from a foam layer extruder into the mold,
Inside the mold, the foamed layer formed from the thermoplastic resin composition for the foamed layer and the non-foamed inner layer formed from the thermoplastic resin composition for the non-foamed layer are formed and uncured. Forming an air conditioning drain pipe,
A method for manufacturing an air-conditioning drain pipe, wherein the unhardened air-conditioning drain pipe is inserted into a pipe outer surface forming tube provided in a cooling water tank connected to the mold and cooled.

Claims (2)

a tubular foam layer containing a vinyl chloride resin (B);
An air conditioning drain pipe provided on the outer surface of the foamed layer and comprising a non-foamed outer layer containing a vinyl chloride resin (A),
The expansion ratio of the foamed layer is 3.5 times or more,
An air-conditioning drain pipe, wherein the vinyl chloride-based resin (A) is a mixture of a vinyl chloride resin and an elastomer resin, or a graft polymer obtained by graft-polymerizing an elastomer resin to a vinyl chloride resin. 2. The air conditioning drain pipe according to claim 1, wherein the vinyl chloride resin contained in the vinyl chloride resin (A) has an average degree of polymerization of 800 or more and 1000 or less.

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