JP2020098024A - Pipe for air conditioning drain, air conditioning drain piping and method for producing pipe for air conditioning drain - Google Patents

Abstract

To provide a pipe for an air conditioning drain that easily can prevent water permeation into a foamed layer.SOLUTION: A pipe for an air conditioning drain 10' has a cylindrical foamed layer 2 containing vinyl chloride resin (B), and a non-foamed inner layer 1 provided on the inner surface of the foamed layer 2 and containing vinyl chloride resin (A). The foamed layer 2 has a closed-cell ratio of 45% or more, a fusing strength of the foamed layer 2 and the non-foamed inner layer 3 is 1.5 MPa or more, and the foamed layer 2 has an average cell diameter of 30 μm or more and 400 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an air conditioning drain pipe.

As an air conditioning drain pipe, one with excellent heat insulation is required. 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, there is a problem that water easily penetrates from the end portion because the end portion of the foam layer is exposed at the pipe joint portion. Water infiltration into the foam layer increases the heat exchange rate and reduces the heat insulating effect.

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

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

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

An object of the present invention is to provide a pipe for an air conditioning drain which can easily prevent water from penetrating into the foam layer.

The inventors of the present application have found that the above problems can be solved by setting the expansion ratio, the closed cell ratio, the average cell diameter, and the fusion strength of the foam layer to a specific numerical range.
The present invention has the following aspects.
[1] A tubular foam layer containing a vinyl chloride resin (B),
A pipe for an air-conditioning drain, which is provided on the inner surface of the foam layer and comprises a non-foam inner layer containing a vinyl chloride resin (A),
The closed cell ratio of the foam layer is 45% or more,
The fusion bonding strength between the foam layer and the non-foam inner layer is 1.5 MPa or more,
A pipe for an air conditioning drain, wherein the foam layer has an average bubble diameter of 30 μm or more and 400 μm or less.
[2] The pipe for an air conditioning drain according to [1], wherein the foamed layer has a closed cell rate of 95% or less.
[3] The pipe for an air conditioning drain according to [1] or [2], wherein the foam layer contains a tin compound.
[4] The pipe for an air conditioning drain according to any one of [1] to [3], wherein the foam layer contains hydrocarbon as a foaming agent.
[5] The pipe for an air conditioning drain according to any one of [1] to [4], wherein the vinyl chloride resin (B) is polyvinyl chloride having an average degree of polymerization of 600 or more and 800 or less.
[6] An air-conditioning drain pipe including the air-conditioning drain pipe according to any one of [1] to [5] and a pipe joint,
An air conditioning drain pipe characterized in that the pipe joint does not have an annular elastic body inside.
[7] A method for manufacturing an air conditioning drain pipe according to any one of [1] to [5],
The thermoplastic resin composition for non-foamed layer is melt-kneaded and extruded by an extruder,
A thermoplastic resin composition for a foam layer in which a foaming agent containing two or more kinds selected from a volatile foaming agent, a decomposable foaming agent, and a heat-expandable capsule is preliminarily blended is melt-kneaded and extruded by an extruder,
The thermoplastic resin composition for a non-foamed layer and the thermoplastic resin composition for a foamed layer are injected into a mold and merged inside the mold to form an uncured air-conditioning drain pipe.
A method for manufacturing an air conditioning drain pipe, characterized by cooling an uncured air conditioning drain pipe and molding the pipe to a predetermined size.

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

It is sectional drawing which shows an example of the pipe for air conditioning drains of this invention. It is a front view which shows the apparatus for measuring fusion strength. It is a top view of a manufacturing device for manufacturing a pipe for air-conditioning drains. It is a front view of the manufacturing apparatus for manufacturing the pipe for air-conditioning drains. It is a block diagram which shows the metal mold|die used for the manufacturing apparatus of the pipe for air-conditioning drains, and the tube for tube outer surface formation. 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 tubular foam layer containing a vinyl chloride resin (B), a non-foaming inner layer provided on the inner surface of the foam layer and containing a vinyl chloride resin (A), and the foam. A non-foamed outer layer provided on the outer surface of the layer and containing a vinyl chloride resin (C).
FIG. 1 is a sectional view showing an example of an air conditioning drain pipe of the present invention. As shown in FIG. 1, an air conditioning drain pipe 10 ′ has 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 an arbitrary 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, the non-foamed inner layer 1, the foamed layer 2, and the non-foamed outer layer 3 are exposed at the end surface (cut surface) of the air conditioning drain pipe 10' inside the receiving port of the pipe joint.
The air-conditioning drain pipe 10' has a high closed-cell rate of the foam layer 2 and the drain drainage flowing down inside the pipe hardly penetrates. Therefore, the adhesive is uniformly applied to the end of the air-conditioning drain pipe as in the conventional case. Alternatively, the annular elastic body may not be provided inside the pipe joint.

The outer diameter of the air conditioning drain pipe 10' is preferably 32 mm or more and 100 mm or less, for example. For example, the inner diameter of the air conditioning drain pipe 10' is preferably 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 6 mm or more and 10 mm or less, for example.

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 further preferably 600 MPa or more and 1000 MPa or less.
By setting the longitudinal elastic modulus 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 of bending and elongation. Can be prevented from being destroyed.
The longitudinal elastic modulus is also called the longitudinal elastic modulus or Young's modulus, and is obtained from the tensile stress and the tensile strain obtained by the tensile test according to JIS K7161-1:2014.
The longitudinal elastic modulus can be adjusted by the degree of polymerization of the vinyl chloride resin, the foaming ratio of the foamed layer, the thickness of each of the non-foamed inner layer 1, the foamed layer 2 and the non-foamed outer layer 3, and the like.

<Non-foamed inner layer>
The non-foamed inner layer 1 contains a vinyl chloride resin (A). As the vinyl chloride resin (A), a homopolymer of vinyl chloride monomer (polyvinyl chloride) may be used, or a vinyl chloride monomer and another monomer which is copolymerizable with the vinyl chloride monomer. It may be a copolymer with the body.
Examples of the other monomer copolymerizable with the vinyl chloride monomer include ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. And the like. These may be used alone or in combination of two or more.
The vinyl chloride resin (A) may be used alone or in combination of two or more kinds. 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 in combination of two or more.
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, and 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, and 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 fear that the drainage drain flowing inside will penetrate into the foamed layer 2, and an air-conditioning drain pipe 10' having excellent heat insulating properties can be obtained.
On the other hand, when the closed-cell rate 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 to prevent the drainage water from penetrating the drain layer itself. The tube 10' can be made lightweight. Further, since the thickness of the foam layer 2 can be increased, the air conditioning drain pipe 10 ′ can have excellent heat insulating properties.

<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. As the vinyl chloride resin (B), a homopolymer of vinyl chloride monomer (polyvinyl chloride) may be used, or a vinyl chloride monomer and another monomer which is copolymerizable with the vinyl chloride monomer. It may be a copolymer with the body.
Examples of the other monomer copolymerizable with the vinyl chloride monomer include ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. And the like. These may be used alone or in combination of two or more.
The vinyl chloride resin (B) may be used alone or in combination of two or more kinds. 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 in combination of two or more.
In the foam layer 2, the content of the vinyl chloride resin (B) with respect to the total weight of the resin is preferably 70% by mass or more and 80% by mass or less, and more preferably 70% by mass or more and 75% by mass or less.

The mass average molecular weight of the vinyl chloride resin (B) is preferably 37500 or more and 70000 or less, and more preferably 37500 or more and 44000 or less.
The weight 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 degree of polymerization of polyvinyl chloride is preferably 600 or more and 800 or less, and more preferably 600 or more and 700 or less.
The average degree of polymerization can be calculated by dividing the mass 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 foamed 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). It is preferable. By including 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 3,000,000 or more and 6,000,000 or less, and more preferably 4,000,000 or more and 5,000,000 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, and 12 parts by mass with respect to 100 parts by mass of the vinyl chloride resin (B). More preferably, it is 18 parts by mass or more and 24 parts by mass or less.
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.
Examples of the volatile foaming agent include aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers and ketones. Among them, examples of the aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), and the alicyclic hydrocarbons include, for example, cyclopentane, cyclohexane and the like. Can be mentioned. Examples of the halogenated hydrocarbon include one or two or more halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane and difluoroethane. Further, examples of the ether include dimethyl ether and diethyl ether, and examples of the ketone include acetone and methyl ethyl ketone.
Examples of the decomposing foaming agent include inorganic foaming agents such as sodium bicarbonate (sodium hydrogen carbonate), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compound, sodium borohydride, azodicarbonamide, barium azodicarboxylate. , Organic foaming agents such as dinitrosopentamethylenetetramine.
Moreover, you may use the heat-expandable capsule in which the said hydrocarbon was included in the thermoplastic resin. In addition, carbon dioxide gas, nitrogen, gas such as air may be used as the foaming agent.
These may be used alone or in combination of two or more.
The amount of the foaming agent used is preferably 1 part by mass or more and 8 parts by mass or less, and more preferably 2 parts by mass or more and 5 parts by mass or less, with respect to 100 parts by mass of the vinyl chloride resin (B).

The foamed layer 2 may include a known stabilizer such as a lead compound (lead stabilizer), a CaZn compound (CaZn stabilizer), a tin compound (tin stabilizer) as a stabilizer. In particular, the inclusion of a stabilizer containing a tin compound facilitates increasing the thermal stability of the resin. The tin compound is preferably a mercapto type, a laurate type, or a malate type.
The presence of these compounds and the content thereof are confirmed by inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical 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 ISO 17353:2004.
The foam layer 2 may contain a lubricant. The inclusion of the lubricant makes it easier to maintain the slidability between the metal surface and the resin. As the lubricant, ester type, polyethylene type and polyethylene oxide type are preferable.

The expansion ratio of the foam layer 2 is 3.5 times or more and 10 times or less, and preferably 4.5 times or more and 6.0 times or less.
By setting the expansion ratio within the above numerical range, high heat insulation can be imparted. Further, by setting the expansion ratio within the above numerical range, the air conditioning drain pipe 10' can be made lightweight.
The expansion ratio can be adjusted according to the type or amount of resin, the type or amount of foaming agent, manufacturing conditions, and the like.
The expansion ratio can be measured by the following method.
[Measuring method of foaming ratio]
A 10 mm or more circumferential direction and 50 mm axial direction were cut out 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 cutter, and only the foam layer 2 was processed into a plate shape having a length of about 50 mm. The thing is used as a test piece. It should be noted that four test pieces are prepared centering on points that are evenly divided into four in the inner peripheral direction.
According to JIS K 7112:1999, a test piece is used to obtain the apparent density up to 3 digits after the decimal point with a water displacement type specific gravity measuring machine at 23° C.±2° C., and the expansion ratio is calculated by the following formula (1).
m=γc/γ (1)
[In the formula (1), m is a foaming ratio, γ is an apparent density (g/cm ³ ) of the foamed layer 2, and γc is a density (g/cm ³ ) of the foamed layer 2 when not foamed. .. ]

The closed cell ratio of the foam layer 2 is 45% or more, preferably 60% or more, and more preferably 80% or more. The upper limit of the closed cell rate 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 the heat insulating property while suppressing the cost and prevent water from penetrating 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 which will be 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 rate is measured according to JIS K 7138:2006.
The closed cell ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, manufacturing conditions, and the like.

The fusion bonding strength between the foamed layer 2 and the non-foamed inner layer 1 is 1.5 MPa or more, preferably 2.0 MPa or more.
By setting the fusion strength within the above range, it is possible to prevent the foam layer 2 and the non-foam inner layer 1 from peeling off.
The fusion strength can be adjusted by the kind or amount of the resin, the kind or amount of the foaming agent, the 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 further 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 the heat insulating property and prevent the permeation of water into the foam layer 2. Even if the air bubbles are not completely closed cells (closed cell ratio is 100%), and even if some of the cell walls are connected to allow water to penetrate, the average cell diameter is within the above numerical range and the closed cell rate is Is within the above numerical range, water does not penetrate deep inside the foam layer 2, and the heat insulating performance does not pose a problem in practical use.
The 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, manufacturing conditions, and the like.

<Non-foamed outer layer>
The non-foamed outer layer 3 contains a vinyl chloride resin (C). As the vinyl chloride resin (C), a homopolymer of vinyl chloride monomer (polyvinyl chloride) may be used, or a vinyl chloride monomer and another monomer which is copolymerizable with the vinyl chloride monomer. It may be a copolymer with the body.
Examples of the other monomer copolymerizable with the vinyl chloride monomer include ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, acrylonitrile. And the like. These may be used alone or in combination of two or more.
The vinyl chloride resin (C) may be used alone or in combination of two or more kinds. 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 in combination of two or more.
In the non-foamed outer layer 3, the content of the vinyl chloride resin (C) with respect to the total weight of the resin is preferably 80% by mass or more and 95% by mass or less, and 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 more than the above lower limit value, it is possible to form the air conditioning drain pipe 10' that is resistant to external impact. By setting the thickness of the non-foamed outer layer 3 to be equal to or less than the above upper limit value, the air conditioning drain pipe 10' can be made lightweight. Further, since the thickness of the foam layer 2 can be increased, the air conditioning drain pipe 10 ′ can have excellent heat insulating properties.
In the case of strengthening by the 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, and more preferably 1.5 mm or more and 3.5 mm or less.
The non-foamed outer layer 3 may contain a pigment. By including the pigment, the appearance can be improved.

≪Manufacturing method for air conditioning drain pipes≫
3 and 4 are overall 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 foam layer extruder 12, a mold 13, a cooling water tank 15, a take-off machine 16, and a cutting machine 17. A mold 13 is connected to the inner/outer layer extruder 11 and the foam layer extruder 12, and a cooling water tank 15 is connected to the mold 13. A pulling machine 16 is connected to the cooling water tank 15, and a cutting machine 17 is connected to the pulling machine 16. Further, as shown in FIGS. 3 and 4, the gas cylinder 18 and the metering pump 19 may be connected to the foam layer extruder 12.
The gas cylinder 18 and the metering pump 19 supply a gaseous foaming agent from the vent hole of the foaming layer extruder 12.
The inner/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 extruding machine 12 melts and kneads the thermoplastic resin composition for foam layer which forms the foam layer 2 and extrudes it into the mold 13.
The mold 13 is composed of a thermoplastic resin composition for a non-foamed layer injected from the inner and outer layer extruder 11 and a thermoplastic resin composition for a foamed layer injected from the foamed layer extruder 12, and is uncured with a three-layer structure. The air-conditioning drain pipe 100' is molded.
The cooling water tank 15 is provided with a tube 14 for forming an outer surface of the uncured air conditioning drain tube 100 ′ for molding the uncured air conditioning drain tube 100 ′ into a predetermined size, and the uncured air conditioning drain tube 100 formed by the mold 13. Is cooled in a state where the outer surface of the tube is in contact with the tube 14 for forming a tube outer surface.
The take-off machine 16 receives the air conditioning drain pipe 10 ′ cooled in the cooling water tank 15.
The cutting machine 17 cuts the air conditioning drain pipe 10 ′ sent from the take-off machine 16 into a predetermined length.

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

Then, as shown in FIG. 5, the thermoplastic resin composition 21 for the non-foamed layer melt-kneaded by the inner and outer layer extruder 11 and the thermoplastic resin composition 22 for the foamed layer melt-kneaded by the foamed layer extruder 12. Are poured 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 for a foam layer between the non-foaming thermoplastic resin layer 31 formed from the non-foaming layer thermoplastic resin composition 21 and the non-foaming inner layer 1 and the non-foaming outer layer 3. 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 discharged from the mold 13, the resin of the foamed thermoplastic resin layer 32 foams. An uncured air conditioning drain pipe 100 ′ is inserted into the pipe outer surface forming tube 14, and the uncured air conditioning drain pipe 100 ′ is cooled in the cooling water tank 15 while being molded to a predetermined size, and is then conditioned. 10'. Further, the cooling-molded air conditioning drain pipe 10 ′ is delivered to the take-off machine 16 and sent to the cutting machine 17, where it is cut into a predetermined length.

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 time for molding with a mold is preferably 10 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less.

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

The components in the table will be described below.
In addition, the content of each component in the table represents parts by mass when the polyvinyl chloride in the foam layer is 100 parts by mass.
<Vinyl chloride resin (B)>
-A-1: Polyvinyl chloride (polymerization degree 640, manufactured by Tokuyama Sekisui Industry Co., Ltd., trade name "TS-640M").
-A-2: Polyvinyl chloride (polymerization degree 800, manufactured by Tokuyama Sekisui Industry Co., Ltd., trade name "TS-800E").
-A-3: Polyvinyl chloride (polymerization degree 500, manufactured by Taiyo PVC Co., Ltd., trade name "TH-500"). -A-4: Polyvinyl chloride (polymerization degree 1000, manufactured by Tokuyama Sekisui Industry 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: 4,000,000, manufactured by Mitsubishi Rayon Co., Ltd., trade name "P-531A").
B-3: Acrylic polymer compound (mass average molecular weight: 5,000,000, manufactured by Kaneka Corporation, trade name "PA-40").
B-4: Acrylic polymer compound (mass average molecular weight: 1,000,000, manufactured by Kaneka Corporation, trade name "PA-20").
B-5: acrylic polymer compound (mass average molecular weight: 8,000,000, manufactured by Kaneka Corporation, trade name "PA-60").
<Foaming agent>
C-1: baking soda (manufactured by Eiwa Chemical Industry Co., Ltd., trade name "Cerbon SC-855").
C-2: Thermally expandable capsule (Tokuyama Sekisui Industry Co., Ltd., trade name "Advancel EM501").
C-3: Azodicarbonamide (manufactured by Eiwa Chemical Industry Co., Ltd., trade name "Vinihol AC").
<Vinyl chloride resin (A) and (C)>
-Polyvinyl chloride (polymerization degree 1000, manufactured by Tokuyama Sekisui Industry Co., Ltd., trade name "TS-1000R").

(Example 1)
100 parts by mass of vinyl chloride resin (B) A-1, 2 parts by mass of tin stabilizer (trade name "STX-80" manufactured by Daikyo Kasei Co., Ltd.), and acrylic polymer compound B-1 Was mixed with 24 parts by mass of baking soda C-1 and 2.2 parts by mass of baking soda C-1 to prepare a thermoplastic resin composition for a foam layer.
100 parts by mass of vinyl chloride resin (A) and (C) as a thermoplastic resin composition for non-foaming layers for inner and outer layers, tin stabilizer (trade name "STX-80", manufactured by Daikyo Kasei Kogyo Co., Ltd.) The resin composition which mixed 2 mass parts of was used.
These compositions were used as an inner/outer layer extruder 11, a foam layer extruder 12, a mold 13, a cooling water tank 15 to which a tube 14 for tube outer surface molding is attached, a take-off machine 16, and a cutting machine 17 shown in FIGS. Extrusion molding was performed using a manufacturing apparatus configured from.
Specifically, the thermoplastic resin composition for a non-foamed layer was kneaded at 190° C. in the inner/outer layer extruder 11 and injected into the mold 13 at an extrusion rate of 40 kg/h. Further, the thermoplastic resin composition for 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 an 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 molding the outer surface of the pipe, cooled in the cooling water tank 15, taken by the take-up machine 16, and then cut into a predetermined length by the cutting machine 17 to obtain three pieces. A layered pipe for air conditioning drain was obtained.

(Examples 2-8, Comparative Examples 1-6)
A three-layer air-conditioning drain pipe was obtained in the same manner as in Example 1 except that the components shown in Tables 1 and 2 were changed.

With respect to each of the obtained air conditioning drain pipes, the closed cell ratio, the average cell diameter, the flatness test, the fusion strength, the expansion ratio, the longitudinal elastic modulus, and the full water test were measured by the following procedures.

[Measurement of closed cell ratio]
A tube for an air-conditioning drain was cut into a length of about 30 mm, and was cut in the circumferential direction so that the peripheral length was about 20 mm, and the non-foamed inner layer and the non-foamed outer layer were removed by an NT cutter to obtain a test piece.
According to JIS K 7138:2006, the volume was measured with an air-comparison hydrometer at 23° C.±2° C., and according to JIS K 7112:1999, the volume obtained with a water displacement-type hydrometer was measured at 23° C.±2° C. The closed cell ratio was measured by the following formula (2).
Cc=(Va/Vaq)×100 (2)
[In the formula (2), Cc is a closed cell ratio (%), Va is an air comparison volume (cm ³ ), and Vaq is a 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 was drawn on the circumferential cross-sectional image of the air conditioning drain pipe photographed with a scanning electron microscope (SEM), and the value obtained by dividing by the number of bubbles on the straight line was taken as the bubble diameter per image. The average value of 8 straight lines and 8 data was defined as the average bubble diameter.

[Flat test]
The air conditioning drain pipe was cut into a length of 50 mm and used as a test piece.
After adjusting the condition of the test piece at 23 ℃ ± 2 ℃ for 1 hour or more, sandwich the test piece between the two compression plates of the flat tester, and 10 mm until the flat load becomes 784 N (80 kgf) or more in the direction perpendicular to the tube axis. The test piece was compressed at a compression speed of /min, and the presence or absence of cracks and cracks in the test piece was confirmed and evaluated according to the following evaluation criteria.
<Evaluation criteria>
◯: No cracks or cracks.
X: There are cracks and cracks.
The obtained results are shown in Tables 1 and 2.

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

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

[Coefficient of longitudinal elasticity]
According to JIS K 7161-1:2014, the longitudinal elastic modulus was measured under the condition of a temperature of 15°C. The obtained results are shown in Tables 1 and 2.

[Fluid test]
FIG. 6 shows a schematic view of the full water test apparatus.
The air conditioning drain pipe 10′ was cut into a length L1 (L1=2000 mm), which was used as a test piece.
The lower end of the test piece is connected to the other closed pipe fitting 50, the upper end of the test piece is also connected to the pipe fitting 51, and the length L2 (the upper part of the pipe fitting 51 is provided with a scale for confirming the water level). L2=2000 mm) of the cylinder 60 is connected to form a full water test apparatus 70. No adhesive was applied to the end surfaces (cut surfaces) of both ends of the air conditioning drain pipe 10' of the test piece.
After fixing the pipe fitting 50 so that the pipe axis of the test piece is vertical, the water level tester 70 has a water level height of L1+L2 (L1+L2=4000 mm) from the end face of the lower end of the test piece. Water was added, and a water head pressure of L1+L2 (L1+L2=4000 mm) was applied to the lower end surface of the test piece.
The amount of decrease in the water level (height of decrease in the water level) after holding for 120 minutes in this state was measured and evaluated according to the following evaluation criteria.
<Evaluation criteria>
◯: The water level reduction height is 0 mm or more and less than 10 mm.
Δ: The height of decrease in water level 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, and thus were difficult to permeate water.
The air-conditioning drain pipe of Comparative Example 1 had a closed cell ratio of 45% or more, but had a large average bubble diameter of 500 μm, and thus was easy to permeate water.
The air-conditioning drain pipes of Comparative Examples 2 to 5 had a closed cell rate of less than 45%, a high open cell rate, and easily permeated water.
Since the air conditioning drain pipe of Comparative Example 6 had a large content of the acrylic polymer compound in the foam layer, it could not flexibly follow the external force and cracked in the flatness test.
From the above results, it was found that the air conditioning drain pipe to which the present invention is applied can easily prevent water from penetrating into the foam layer.

1 Non-foaming inner layer 2 Foaming layer 3 Non-foaming outer layer 10' Air conditioning drain pipe

Claims (7)

A tubular foam layer containing vinyl chloride resin (B),
A pipe for an air-conditioning drain, which is provided on the inner surface of the foam layer and comprises a non-foam inner layer containing a vinyl chloride resin (A),
The closed cell ratio of the foam layer is 45% or more,
The fusion bonding strength between the foam layer and the non-foam inner layer is 1.5 MPa or more,
A pipe for an air conditioning drain, wherein the foam layer has an average bubble diameter of 30 μm or more and 400 μm or less. The air conditioning drain pipe according to claim 1, wherein the foamed layer has a closed cell rate of 95% or less. The air conditioning drain pipe according to claim 1 or 2, wherein the foam layer contains a tin compound. The air conditioning drain pipe according to any one of claims 1 to 3, wherein the foam layer contains hydrocarbon as a foaming agent. The air conditioning drain pipe according to any one of claims 1 to 4, wherein the vinyl chloride resin (B) is polyvinyl chloride having an average degree of polymerization of 600 or more and 800 or less. An air-conditioning drain pipe comprising the air-conditioning drain pipe according to any one of claims 1 to 5 and a pipe joint,
An air conditioning drain pipe characterized in that the pipe joint does not have an annular elastic body inside. A method for manufacturing an air conditioning drain pipe according to any one of claims 1 to 5,
The thermoplastic resin composition for non-foamed layer is melt-kneaded and extruded by an extruder,
A thermoplastic resin composition for a foam layer in which a foaming agent containing two or more kinds selected from a volatile foaming agent, a decomposable foaming agent, and a heat-expandable capsule is preliminarily blended is melt-kneaded and extruded by an extruder,
The thermoplastic resin composition for a non-foamed layer and the thermoplastic resin composition for a foamed layer are injected into a mold and merged inside the mold to form an uncured air-conditioning drain pipe.
A method for manufacturing an air conditioning drain pipe, characterized by cooling an uncured air conditioning drain pipe and molding the pipe to a predetermined size.

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