JP7271078B2 - Air conditioning drain pipe - Google Patents

Description

The present invention relates to an air conditioning drain pipe.

Air-conditioning drain pipes are required to have excellent heat insulating properties. As such an air-conditioning drain pipe, a pipe containing polyvinyl chloride and having a foam layer and a non-foam inner layer laminated on the inner surface thereof is preferably used.
However, in the conventional air-conditioning drain pipe, since the end of the foam layer is exposed at the pipe joint, there is a problem that water easily permeates from the end. When water permeates the foam layer, the heat exchange rate increases and the heat insulating effect decreases.

Patent Literature 1 proposes a method of preventing permeation of water into a foam layer by applying an adhesive to the ends of the foam layer to cover the ends of the foam layer.
Patent Literature 2 proposes a method of preventing water from penetrating into a foam layer using an annular elastic body.

JP-A-7-68674 JP-A-9-184583

However, in the method of Patent Document 1, it is necessary to uniformly apply the adhesive, and the work is complicated. Moreover, in the method of Patent Document 2, it is necessary to use a special member, and the work is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air-conditioning drain pipe that can easily prevent water from permeating into a foam layer.

The inventors of the present application have found that the above problems can be solved by setting the foaming ratio, closed cell ratio, average cell diameter, and fusion bond strength of the foam layer to specific numerical ranges.
The present invention has the following aspects.
[1] A cylindrical foam layer containing a vinyl chloride resin (B);
A non-foamed inner layer provided on the inner surface of the foamed layer and containing a vinyl chloride resin (A);
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 (C),
The expansion ratio of the foam layer is 3.5 times or more and 10 times or less,
The closed cell rate of the foam layer is 45% or more,
The fusion strength between the foamed layer and the non-foamed inner layer is 1.5 MPa or more,
An air-conditioning drain pipe, wherein the foam layer has an average cell diameter of 30 μm or more and 400 μm or less.
[2] The air conditioning drain pipe according to [1], wherein the vinyl chloride resin (B) is polyvinyl chloride having an average degree of polymerization of 600 or more and 800 or less.
[3] The air-conditioning drain pipe according to [1] or [2], wherein the foam layer contains an acrylic polymer compound.

ADVANTAGE OF THE INVENTION According to this invention, the pipe for air-conditioning drains which can prevent permeation|permeation of the water to a foam layer easily can be provided.

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. 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; It is a front view which shows the outline of a full water test apparatus.

≪Air conditioning drain pipe≫
The air-conditioning drain pipe of the present invention comprises a cylindrical foamed layer containing a vinyl chloride resin (B), a non-foamed inner layer provided on the inner surface of the foamed layer and containing the vinyl chloride resin (A), and the foamed A non-foamed outer layer provided on the outer surface of the layer and containing a vinyl chloride resin (C).
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, a non-foam inner layer 1 laminated on the inner surface of the foam layer 2, and a non-foam outer layer laminated on the outer surface of the foam layer 2. 3 and .

The air-conditioning drain pipe 10' is cut to any length at the construction site, and the end of the air-conditioning drain pipe 10' is inserted into the socket of a pipe joint (not shown) such as a socket, elbow, or cheese. Connected. 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 non-foamed inner layer 1, the foamed layer 2, and the non-foamed outer layer 3 are exposed on the end face (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 is difficult to permeate. Also, 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 non-foamed inner layer 1, the foamed layer 2, and the non-foamed 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 these external forces while suppressing deformation such as bending and elongation. can be prevented from being destroyed.
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 foamed layer, the thickness of each of the non-foamed inner layer 1, foamed layer 2 and non-foamed outer layer 3, and the like.

<Non-foaming inner layer>
The non-foamed inner layer 1 contains a vinyl chloride resin (A). The vinyl chloride resin (A) may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride), or a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. It may be a copolymer with a body.
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.
The vinyl chloride resin (A) may be used alone, or two or more of them may be used in combination.
The non-foamed inner layer 1 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.
In the non-foamed inner layer 1, the content of the vinyl chloride resin (A) with respect to the total mass of the resin is preferably 80% by mass or more and 95% by mass or less, more preferably 85% by mass or more and 90% by mass 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.

<Foam layer>
The foam layer 2 is formed by foaming a thermoplastic resin composition for a foam layer containing a resin containing a vinyl chloride resin (B) and a foaming agent. The vinyl chloride resin (B) may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride), or a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. It may be a copolymer with a body.
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.
The vinyl chloride resin (B) may be used alone, or two or more of them may be used in combination.
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.
In the foam layer 2, the content of the vinyl chloride resin (B) with respect to the total mass of the resin is preferably 70% by mass or more and 80% by mass or less, more preferably 70% by mass or more and 75% by mass or less.

The weight average molecular weight of the vinyl chloride resin (B) is preferably 37,500 or more and 70,000 or less, more preferably 37,500 or more and 44,000 or less.
The mass average molecular weight is a value measured by gel permeation chromatography using polyethylene glycol as a standard substance.
When the vinyl chloride resin (B) is polyvinyl chloride, the average polymerization degree of polyvinyl chloride is preferably 600 or more and 800 or less, more preferably 600 or more and 700 or less.
The average degree of polymerization can be calculated by dividing the weight average molecular weight by the molecular weight of chloroethylene.
The vinyl chloride resin (B) may be the same as or different from the vinyl chloride resin (A).

The foam layer 2 contains acrylic acid, methacrylic acid, acrylic acid ester, or methacrylic acid ester (collectively referred to as an acrylic polymer compound) as a thermoplastic resin other than the vinyl chloride resin (B). is preferred. By containing the acrylic polymer, the closed cell ratio can be improved and the cell diameter can be made finer.
The mass average molecular weight of the acrylic polymer compound is preferably 3 million or more and 6 million or less, more preferably 4 million or more and 5 million or less.
When the foam layer 2 contains an acrylic polymer compound, the content of the acrylic polymer compound is preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin (B), and 12 parts by mass. Part or more and 36 mass parts or less are more preferable, and 18 mass parts or more and 24 mass parts or less are more preferable.
The thickness of the foam layer 2 is preferably 4.0 mm or more and 10 mm 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 amount of the foaming agent used is preferably 1 part by mass or more and 8 parts by mass or less, more preferably 2 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the vinyl chloride resin (B).

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 and 10 times or less, preferably 4.5 times or more and 6.0 times or less.
By setting the foaming ratio within the above numerical range, high heat insulating properties can be imparted. Further, by setting the foaming ratio within the above numerical 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]
A portion of 10 mm or more in the circumferential direction and 50 mm in the axial direction was cut from the air-conditioning drain pipe 10′, the non-foamed inner layer 1 and the non-foamed outer layer 3 were cut with a milling machine, and only the foamed layer 2 was processed into a plate shape of about 50 mm in length. Use the object as 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 foam layer 2 has a closed cell rate of 45% or more, preferably 60% or more, and more 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 numerical range, it is possible to improve heat insulating properties while suppressing costs, and to prevent permeation of water 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.
A closed-cell rate is measured based on JISK7138:2006.
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.

The fusion strength between the foam layer 2 and the non-foam inner layer 1 is 1.5 MPa or more, preferably 2.0 MPa or more.
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.

The average cell diameter of the foam layer 2 is 30 μm or more and 400 μm or less, preferably 50 μm or more and 400 μm or less, more preferably 50 μm or more and 250 μm or less, and even more preferably 60 μm or more and 200 μm or less.
By setting the average cell diameter within the above numerical range, it is possible to improve heat insulation and prevent permeation of water 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 numerical range, and the closed cell ratio is is within the above numerical range, water does not permeate deep into the foam layer 2, and there is no problem with the heat insulating performance in practical use.
A method for measuring the average bubble diameter will be described later.
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.

<Non-foaming outer layer>
The non-foamed outer layer 3 contains vinyl chloride resin (C). The vinyl chloride resin (C) may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride), or a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. It may be a copolymer with a body.
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.
The vinyl chloride resin (C) may be used alone, or two or more of them may be used in combination.
The non-foamed outer layer 3 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.
In the non-foamed outer layer 3, the content of the vinyl chloride resin (C) with respect to the total mass of the resin is preferably 80% by mass or more and 95% by mass or less, more preferably 85% by mass or more and 90% by mass or less.
The vinyl chloride resin (C) may be the same as or different from the vinyl chloride resin (A).
The vinyl chloride resin (C) may be the same as or different from the vinyl chloride resin (B).
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 setting the thickness of the non-foamed outer layer 3 to be equal to or greater than the lower limit, the air-conditioning drain pipe 10' can be made resistant to 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.

<<Manufacturing method for air conditioning drain pipe>>
3 and 4 are general block diagrams of a manufacturing apparatus 20 for manufacturing the three-layer air-conditioning drain pipe 10'. 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. 3 and 4, 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. 5, 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 ′ is a non-foamed thermoplastic resin layer 31 formed from a non-foamed layer thermoplastic resin composition 21, and a non-foamed layer for the foamed layer between the non-foamed inner layer 1 and the non-foamed outer layer 3. and a foamed thermoplastic resin layer 32 formed from the thermoplastic 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.

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. In addition, Examples 1, 5, and 8 are reference 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)>
A-1: Polyvinyl chloride (degree of polymerization 640, trade name “TS-640M” manufactured by Tokuyama Sekisui Kogyo Co., Ltd.).
A-2: Polyvinyl chloride (degree of polymerization 800, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name “TS-800E”).
· A-3: Polyvinyl chloride (degree of polymerization 500, manufactured by Taiyo Vinyl Co., Ltd., trade name "TH-500").
· A-4: Polyvinyl chloride (degree of polymerization: 1000, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name “TS-1000R”).
<Acrylic polymer compound>
B-1: Acrylic polymer compound (mass average molecular weight: 3,000,000, manufactured by Mitsubishi Rayon Co., Ltd., trade name: “P-530A”).
B-2: Acrylic polymer compound (mass average molecular weight: 4 million, manufactured by Mitsubishi Rayon Co., Ltd., trade name “P-531A”).
B-3: Acrylic polymer compound (mass average molecular weight: 5 million, manufactured by Kaneka, trade name “PA-40”).
B-4: Acrylic polymer compound (mass average molecular weight: 1,000,000, manufactured by Kaneka, trade name “PA-20”).
· B-5: Acrylic polymer compound (mass average molecular weight: 8 million, manufactured by Kaneka, trade name “PA-60”).
<Blowing agent>
· C-1: Baking soda (manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name “Celbon SC-855”).
· C-2: Thermally expandable capsule (trade name “Advancel EM501” manufactured by Tokuyama Sekisui Kogyo Co., Ltd.).
· C-3: Azodicarbonamide (manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name “Vinihole AC”).
<Vinyl chloride resins (A) and (C)>
· Polyvinyl chloride (degree of polymerization: 1000, trade name: TS-1000R, manufactured by Tokuyama Sekisui Kogyo Co., Ltd.).

(Example 1)
100 parts by mass of vinyl chloride resin (B) A-1, 2 parts by mass of tin-based stabilizer (manufactured by Daikyo Kasei Kogyo Co., Ltd., trade name "STX-80"), and acrylic polymer compound B-1 and 2.2 parts by mass of sodium bicarbonate C-1 were mixed to prepare a thermoplastic resin composition for a foam layer.
As a thermoplastic resin composition for non-foamed layers for inner and outer layers, 100 parts by mass of vinyl chloride resins (A) and (C) are added with a tin-based stabilizer (manufactured by Daikyo Kasei Kogyo Co., Ltd., trade name "STX-80" ) was mixed with 2 parts by mass of the resin composition.
These compositions were subjected to an inner and outer layer extruder 11, a foam 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 190° C. by the inner and outer layer extruder 11 and injected into the mold 13 at an extrusion rate of 40 kg/h. Also, the thermoplastic resin composition for the foam layer was kneaded at 190° C. by the foam layer extruder 12 and injected into the mold 13 at 60 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.

(Examples 2 to 8, Comparative Examples 1 to 6)
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.

For the obtained air-conditioning drain pipe of each example, closed cell ratio, average cell diameter, flattening test, fusion bond strength, expansion ratio, longitudinal elastic modulus, and full water test were measured by the following procedures.

[Measurement of Closed Cell Ratio]
An air-conditioning drain pipe was 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 a non-foamed inner layer and a non-foamed outer layer were removed with an NT cutter to obtain a test piece.
According to JIS K 7138: 2006, measure the volume with an air comparison type hydrometer at 23 ° C. ± 2 ° C., and measure the volume obtained with a water displacement hydrometer at 23 ° C. ± 2 ° C. according to JIS K 7112: 1999, The closed cell ratio was measured by the following formula (2).
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 obtained results are shown in Tables 1 and 2.

[Measurement of average bubble diameter]
According to JIS K 6400-1, a 1800 μm straight line is drawn on a circumferential cross-sectional image of an air conditioning drain pipe taken with a scanning electron microscope (SEM), and the value obtained by dividing by the number of bubbles on the straight line is taken as the bubble diameter. The average value of 8 straight lines and 8 data was taken as the average bubble diameter.

[Flatness test]
An air-conditioning drain pipe was cut to a length of 50 mm, and this was used as a test piece.
After adjusting the state of the test piece at 23 ° C ± 2 ° C for 1 hour or more, it is sandwiched between two compression plates of a flattening tester, and the flat load is 784 N (80 kgf) or more in the direction perpendicular to the tube axis. /min, and the presence or absence of cracks and cracks in the test piece was checked and evaluated according to the following evaluation criteria.
<Evaluation Criteria>
◯: No cracks or cracks.
x: Cracks and cracks are present.
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 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. bottom. 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. ]
Tables 1 and 2 show the average values of the obtained results.

[modulus of longitudinal elasticity]
In accordance with JIS K 7161-1:2014, the longitudinal elastic modulus was measured at a temperature of 15°C. The obtained results are shown in Tables 1 and 2.

[Full water test]
FIG. 6 shows a schematic diagram of the full water test apparatus.
The air-conditioning drain pipe 10' was cut to length L1 (L1=2000 mm), and this was used as a test piece.
A pipe joint 50 whose other end is closed is connected to the lower end of the test piece, a pipe joint 51 is also connected to the upper end of the test piece, and a length L2 ( L2=2000 mm) cylinder 60 is connected to make a full water test device 70. The adhesive was not applied to the end surfaces (cut surfaces) of both ends of the air-conditioning drain pipe 10' of the test piece.
After fixing the full water test apparatus 70 so that the pipe joint 50 is on the bottom side and the pipe axis of the test piece is vertical, the water level height from the end surface of the lower end of the test piece is L1 + L2 (L1 + L2 = 4000 mm). Distilled water was added, and a water head pressure of L1+L2 (L1+L2=4000 mm) was applied to the end surface of the lower end of the test piece.
After holding this state for 120 minutes, the amount of decrease in the water level (height of decrease in water level) was measured and evaluated according to the following evaluation criteria.
<Evaluation Criteria>
◯: The height of decrease in water level is 0 mm or more and less than 10 mm.
Δ: The height of water level reduction is 10 mm or more and less than 20 mm.
x: The height of decrease in water level is 20 mm or more.
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 8 had a closed cell ratio of 45% or more and a small average cell diameter, which made it difficult for water to permeate.
The air-conditioning drain pipe of Comparative Example 1 has a closed cell ratio of 45% or more, but has a large average cell diameter of 500 μm, so water easily permeates it.
The air-conditioning drain pipes of Comparative Examples 2 to 5 had closed cell ratios of less than 45%, high open cell ratios, and permeation of water easily.
Since the air-conditioning drain pipe of Comparative Example 6 contained a large amount of the acrylic polymer compound in the foam layer, it could not flexibly follow the external force and cracked in the flattening test.
From the above results, it was found that the air-conditioning drain pipe to which the present invention is applied can easily prevent permeation of water into the foam layer.

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

Claims (1)

a foam layer formed by cylindrically molding a thermoplastic resin composition for a foam layer containing a vinyl chloride resin (B), a tin stabilizer, and a decomposable foaming agent;
A non-foamed inner layer formed by molding a thermoplastic resin composition for a non-foamed layer that contains a vinyl chloride resin (A) and does not contain a foaming agent, which is laminated on the inner surface of the foamed layer;
An air conditioning drain pipe provided on the outer surface of the foam layer and comprising a non-foamed outer layer formed of a thermoplastic resin composition for a non-foamed layer containing a vinyl chloride resin (C) and not containing a foaming agent, ,
The expansion ratio of the foamed layer is 4.5 times or more and 6 times or less,
The closed cell ratio of the foam layer is 48 % or more and 81 % or less,
The fusion strength between the foamed layer and the non-foamed inner layer is 2.0 MPa or more,
The foam layer has an average cell diameter of 100 μm or more and 201 μm or less ,
The vinyl chloride resin (B) is polyvinyl chloride having an average polymerization degree of 600 or more and 800 or less,
The foam layer contains an acrylic polymer compound,
The air-conditioning drain pipe , wherein the content of the acrylic polymer compound is 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin (B).

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