JP6916025B2 - Resin pipe fitting - Google Patents

Description

The present invention relates to a resin pipe joint used for connecting a drain pipe or the like.

Conventionally, it is common to prevent dew condensation around the pipe by covering the pipe made of a steel pipe or a synthetic resin pipe for draining the drain water of the air conditioning equipment with a heat insulating material such as glass wool.
However, in the above-mentioned conventional method, the work efficiency is poor because the work of winding or covering the heat insulating material is required in addition to the work of piping, and the work may not be performed in a narrow work space.
Therefore, resin pipes and pipe joints having a foam layer as a heat insulating layer have been proposed. By providing the heat insulating layer, it is possible to prevent dew condensation without covering with a heat insulating material after the piping is constructed.

Patent Document 1 includes a heat insulating layer made of foamed resin inside the main body, and a pipe with a heat insulating layer having a structure in which the inner and outer walls of the main body surrounding the heat insulating layer and the connecting portion are integrally molded by injection molding. Fittings have been proposed.

Japanese Patent No. 3699579

In recent years, the applications of resin pipe joints have expanded, and for example, there is a need for vinyl chloride resin resin pipe joints having excellent chemical resistance. In addition, when connecting other piping materials to the resin pipe joint, make the connection part (accepting part) of the resin pipe joint transparent or translucent so that the inserted state of the pipe inside the joint can be visually recognized. There is a need.
If a resin pipe joint is simply manufactured from a vinyl chloride resin, the non-foamed layer cannot be made transparent. In response to these problems, the present inventors have found that the non-foaming layer can be made transparent by using a tin-based stabilizer in the non-foamable resin composition.
However, when a resin pipe joint is manufactured from a vinyl chloride resin, there is a problem that the interface between the foamed layer and the non-foamed layer turns black and the appearance is poor.
Therefore, an object of the present invention is a resin pipe joint having excellent heat insulating properties and chemical resistance and having a good appearance.

When a resin pipe joint is manufactured from a vinyl chloride resin, a lead stabilizer is generally used in order to suppress thermal deterioration during processing of the vinyl chloride resin. When a lead-based stabilizer is used, the non-foamed layer cannot be made transparent.
As a result of repeated diligent studies, the present inventors have found that the non-foaming layer can be made transparent by using a tin-based stabilizer in the non-foamable resin composition.
On the other hand, since there is no need to make the foam layer transparent or translucent, a lead-based stabilizer is used.
However, when a resin pipe joint is formed by using a tin-based stabilizer for the non-foamable resin composition and a lead-based stabilizer for the foamable resin composition, the interface between the foamed layer and the non-foamed layer turns black. I found out.
According to the findings of the present inventors, sulfide in which the interface between the foamed layer and the non-foamed layer turns black due to the reaction between the sulfur component contained in the tin-based stabilizer and the lead contained in the lead-based stabilizer. It is thought that a phenomenon called pollution is occurring.
Therefore, the present inventors have stated that when a tin-based stabilizer is used in the foamable resin composition, sulfide contamination is prevented, the non-foamed layer is transparent or translucent, and a resin pipe joint having a good appearance can be obtained. I found it.

In order to solve the above problems, the present invention has the following aspects.
[1] In a resin pipe joint including a main body portion having a flow path inside and openings formed at both ends, and a receiving portion surrounding the peripheral edge of the opening of the main body portion, the main body portion is a foam layer. And a non-foaming layer covering both sides of the foaming layer, and the foaming layer is formed by foaming a foamable resin composition containing a first vinyl chloride resin, a foaming agent, and a first stabilizer. The non-foaming layer is formed by molding a non-foamable resin composition containing a second vinyl chloride resin and a second stabilizer, and the foamed layer and the non-foaming layer are substantially the same. A resin pipe joint that does not contain lead and the non-foaming layer is transparent or translucent.
[2] The resin pipe joint according to [1], wherein the receiving portion is formed of the non-foamed layer.
[3] The resin pipe joint according to [1] or [2], wherein the second stabilizer is a tin-based stabilizer.
[4] The resin pipe joint according to [3], wherein the content of the tin-based stabilizer is 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the second vinyl chloride resin. ..

According to the present invention, it is possible to provide a resin pipe joint having excellent heat insulating properties and chemical resistance and having a good appearance.

It is a side view which shows one Embodiment of the resin pipe joint of this invention. It is a vertical sectional view of the resin pipe joint shown in FIG.

[Resin pipe fitting]
The resin pipe joint of the present invention includes a main body portion having a flow path inside and openings formed at both ends, and a receiving portion surrounding the peripheral edge of the opening of the main body portion.
The main body includes a foam layer and a non-foam layer that covers both sides of the foam layer.
The foamed layer is formed by foaming and molding a foamable resin composition containing a first vinyl chloride resin, a foaming agent, and a first stabilizer.
The non-foamed layer is formed by molding a resin composition containing a second vinyl chloride resin and a second stabilizer.
The foamed layer and the non-foamed layer are substantially lead-free.
The non-foamed layer is transparent or translucent.

In the present specification, "substantially lead-free" means that the lead content is less than 0.1 parts by mass with respect to 100 parts by mass of the foamable resin composition, and it is measured by ICP emission spectroscopic analysis. This means that the concentration in the sample solution is less than 100 ppm. The lead content is preferably 0 parts by mass.

As used herein, "transparent or translucent" means that the inside of the joint can be visually recognized from the outside of the joint with the naked eye.

Hereinafter, the resin pipe joint according to the embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the resin pipe joint 1 according to the present embodiment uses an elbow used for connecting a drain pipe as an example. The resin pipe joint 1 includes a main body portion 10 having a flow path that bends inside and having openings 12a and openings 12b at both ends. The resin pipe joint 1 includes a cylindrical receiving portion 20a surrounding the peripheral edge of the opening 12a of the main body 10, and a cylindrical receiving portion 20b surrounding the peripheral edge of the opening 12b of the main body 10. The main body portion 10, the receiving portion 20a, and the receiving portion 20b are integrally formed.

FIG. 2 is a vertical cross-sectional view of the resin pipe joint shown in FIG. As shown in FIG. 2, the main body 10 includes a foam layer 30 and a non-foam layer 50. Both sides of the foam layer 30 are covered with the non-foam layer 50. The receiving portion 20a and the receiving portion 20b are formed of a non-foamed layer 50. A part of the foamed layer 30 is formed by biting into the non-foamed layer 50 of the receiving portion 20a. Further, the foamed layer 30 is formed by partially biting into the non-foamed layer 50 of the receiving portion 20b.

<Foam layer>
The foamed layer of the present embodiment is formed by foaming and molding a foamable resin composition. The resin pipe joint of the present invention is more excellent in heat insulating property because it has a foamed layer. Both sides of the foam layer are covered with a non-foam layer.
From the viewpoint of improving the appearance of the resin pipe joint, the foam layer is substantially free of lead.

The foaming ratio in the foamed layer is preferably 3.5 to 10 times, more preferably 4.5 to 6.0 times.
By setting the foaming ratio within the above range, high heat insulating properties can be imparted.
The foaming ratio can be adjusted according to the type or amount of the resin, the type or amount of the foaming agent, the production conditions, and the like.
The foaming ratio can be measured by the following method.

(Measuring method of foaming magnification)
A test piece is obtained by cutting out 10 mm or more in the circumferential direction and 50 mm in the axial direction from the main body of the resin pipe joint, cutting the non-foamed layer with a milling cutter, and processing only the foamed layer into a plate shape having a length of about 50 mm. It should be noted that four test pieces shall be prepared centering on the points evenly divided into four in the inner peripheral direction.
According to JIS 7122, the apparent density of the test piece is obtained up to 3 digits after the decimal point using a water substitution type gravity measuring instrument at 23 ° C. ± 2 ° C., and the foaming ratio is calculated by the following formula (1).
m = γc / γ ・ ・ ・ (1)
[In the formula (1), m is the foaming ratio, γ is the apparent density of the foamed layer (g / cm ³ ), and γc is the density of the foamed layer when it is not foamed (g / cm ³ ). The density of the foamed layer when it is not foamed can be measured from the melted foamed layer. ]

<Effervescent resin composition>
The foamable resin composition of the present embodiment contains a first vinyl chloride resin, a foaming agent, and a first stabilizer.
As the first vinyl chloride resin, a hard vinyl chloride resin known as a material for resin pipe joints can be used. The rigid vinyl chloride resin is a vinyl chloride resin that does not substantially contain a plasticizer. The first vinyl chloride-based resin may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride), or a vinyl chloride monomer and another single amount copolymerizable with the vinyl chloride monomer. It may be a copolymer with a body.
Examples of other monomers 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, and acrylonitrile. Etc. can be mentioned. These may be used alone or in combination of two or more.
The first vinyl chloride resin may be used alone or in combination of two or more.
The foamable resin composition may contain a thermoplastic resin other than the first vinyl chloride resin. 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 foamable resin composition, the content of the first vinyl chloride resin with respect to the total mass of the resin is preferably 70 to 80% by mass, more preferably 70 to 75% by mass.

The mass average molecular weight of the first vinyl chloride resin is preferably 37500 to 70000, preferably 37500 to 44000.
The mass average molecular weight is a value measured by gel permeation chromatography using polyethylene glycol as a standard substance.
When the first vinyl chloride resin is polyvinyl chloride, the average degree of polymerization of polyvinyl chloride is preferably 600 to 800, more preferably 600 to 700.
The average degree of polymerization can be calculated by dividing the mass average molecular weight by the molecular weight of chloroethylene.

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, ketones and the like. Among these, examples of aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), and examples of alicyclic hydrocarbons include cyclopentane and cyclohexane. Can be mentioned. Examples of the halogenated hydrocarbon include one or more kinds of halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane and difluoroethane. Further, examples of the ether include dimethyl ether, diethyl ether and the like, and examples of the ketone include acetone, methyl ethyl ketone and the like.
Examples of the decomposable foaming agent include inorganic foaming agents such as sodium bicarbonate (sodium hydrogen carbonate, baking soda), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compound, sodium borohydride, azodicarboxylic amide, and azodicarboxylic. Examples thereof include organic foaming agents such as barium acid acid and dinitrosopentamethylenetetramine.
In addition, a gas such as carbon dioxide, nitrogen, or air may be used as the foaming agent.
From the viewpoint of excellent foaming performance, a decomposing foaming agent is preferable, and baking soda and azodicarbonamide are more preferable.
These may be used alone or in combination of two or more.

The content of the foaming agent is preferably 0.1 part by mass or more and 10 parts by mass or less, more preferably 0.2 parts by mass or more and 5 parts by mass or less, with respect to 100 parts by mass of the first vinyl chloride resin. More preferably, it is 5 parts by mass or more and 2 parts by mass or less.
When the content of the foaming agent is at least the above lower limit value, a sufficient foaming ratio can be easily obtained. When it is not more than the upper limit value, it is easy to suppress the occurrence of discoloration (discolored foreign matter).

As the first stabilizer, a compound other than the lead-based stabilizer known as the stabilizer for the first vinyl chloride resin can be used.
When a stabilizer containing lead or zinc is contained in the foamable resin composition, the decomposition of the organic foaming agent containing a nitrogen atom such as azodicarbonamide is activated, and the foaming start temperature is lowered. As a result, foaming residue is generated at an early stage, and the foaming residue tends to cause product defects called discoloration (discolored foreign matter), which is not preferable.
In addition, the lead-based stabilizer reacts with the sulfur component in the foamable resin composition to cause sulfurization contamination in which the interface between the foamed layer and the non-foamed layer turns black, and the non-foamed layer of the resin pipe joint is transparent. It is not preferable because the sex cannot be guaranteed.
From this point of view, the foamed layer and the non-foamed layer of the resin pipe joint of the present invention are required to be substantially free of lead.

The first stabilizer in the foamable resin composition is preferably a tin-based stabilizer. By using a tin-based stabilizer, it becomes easy to improve the thermal stability of the first vinyl chloride-based resin, and the occurrence of discoloration can be suppressed. As the tin-based stabilizer, an organic acid salt of alkyl tin can be used. Examples of the alkyl group include three types of methyl, butyl and octyl. Examples of the organic acid include mercapto compounds such as an ester of thioglycolic acid and an ester of mercaptoethanol. From the viewpoint of ensuring the transparency of the non-foamed layer, the tin-based stabilizer is preferably a mercapto-based compound. For example, dibutyl tin mercaptan, dioctyl tin mercaptan and the like can be mentioned.
These tin-based stabilizers may be used alone or in combination of two or more. From the viewpoint of further enhancing the thermal stability of the first vinyl chloride resin and improving the processability, it is preferable to use two or more tin-based stabilizers in combination.

The content of the tin-based stabilizer is preferably 100% by mass with respect to the total mass of the first stabilizer.
The content of the tin-based stabilizer is preferably 0.1 part by mass or more and 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the first vinyl chloride resin. It is preferable, and more preferably 1 part by mass or more and 5 parts by mass or less. When the content of the tin-based stabilizer is at least the above lower limit value, the thermal stability of the first vinyl chloride resin is likely to be improved, and the appearance of the resin pipe joint is likely to be improved. When it is not more than the upper limit value, it is easy to increase the foaming ratio of the foamable resin composition.

(Arbitrary ingredient)
The foamable resin composition of the present invention contains components other than the first vinyl chloride resin, the foaming agent, and the first stabilizer (the first optional component) as long as the effects of the present invention are not impaired. But it may be. Examples of the first optional component include known additives such as lubricants, processing aids, and colorants.
The content of the first optional component is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the first vinyl chloride resin. The content of the first optional component may be zero.

<Non-foam layer>
The non-foaming layer of the present embodiment is formed by molding a non-foaming resin composition. By having the non-foamed layer, the resin pipe joint of the present invention can increase the strength of the resin pipe joint. The non-foamed layer is transparent or translucent. From the viewpoint of improving the appearance of the resin pipe joint, the non-foamed layer is substantially free of lead.
Since the non-foaming layer is transparent or translucent, it is preferable that the receiving portion of the resin pipe joint is formed of the non-foaming layer. If the receiving portion of the resin pipe joint is transparent or translucent, the state of insertion can be visually recognized when another piping material is inserted into the receiving portion of the resin pipe joint. Therefore, it is possible to prevent poor connection between other piping materials and the resin pipe joint.

<Non-foamable resin composition>
The non-foamable resin composition of the present embodiment contains a second vinyl chloride resin and a second stabilizer.
Examples of the second vinyl chloride resin include the same resins as the above-mentioned first vinyl chloride resin. The second vinyl chloride resin may be the same as or different from the first vinyl chloride resin.
In the non-foamable resin composition, the content of the second vinyl chloride resin with respect to the total mass of the resin is preferably 80 to 95% by mass, more preferably 85 to 90% by mass.

As the second stabilizer in the non-foamable resin composition, the same stabilizer as the first stabilizer described above can be used. The second stabilizer may be the same as or different from the first stabilizer. From the viewpoint of ensuring the transparency of the non-foamed layer of the resin pipe joint, the second stabilizer is preferably a tin-based stabilizer, and more preferably a mercapto-based tin compound.

The content of the tin-based stabilizer is preferably 100% by mass with respect to the total mass of the second stabilizer.
The content of the tin-based stabilizer is preferably 0.1 part by mass or more and 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the second vinyl chloride resin. It is preferable, and more preferably 1 part by mass or more and 5 parts by mass or less. When the content of the tin-based stabilizer is at least the above lower limit value, the thermal stability of the second vinyl chloride resin can be more easily enhanced, and the transparency of the non-foamed layer can be easily ensured. When it is not more than the upper limit value, the heat resistance of the non-foamable resin composition can be more easily increased.

(Arbitrary ingredient)
The non-foamable resin composition of the present invention may contain components other than the second vinyl chloride resin and the second stabilizer (second optional component) as long as the effects of the present invention are not impaired. .. Examples of the second optional component include known additives such as lubricants, processing aids, and colorants. The second optional component may be the same as or different from the first optional component.
The content of the second optional component is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the second vinyl chloride resin. The content of the second optional component may be zero.

The foamable resin composition of the present invention can contain a first vinyl chloride resin, a foaming agent, a first stabilizer, and a first optional component. The foamable resin composition may be a mixture in which all the components are mixed in advance, or may be a form in which a part or all of all the components are mixed in the molding machine. The mixture in which all the components are premixed may be in the form of powder or pellets. The same applies to the non-foamable resin composition as well as the foamable resin composition.

<Manufacturing method of resin pipe fittings>
Resin pipe fittings are manufactured by injection molding.
For example, as described in Patent Document 1, a non-foamable resin composition is heated and melted and injected into a mold, and then the foamable resin composition is heated and melted and injected into the same mold. Therefore, a resin pipe joint having a foamed layer provided inside the non-foamed layer can be obtained.

In the injection molding machine, the temperature (molding temperature) immediately before being injected into the mold of the heat-melted non-foamable resin composition is preferably 170 ° C. or higher and 190 ° C. or lower, more preferably 180 ° C. or higher and 190 ° C. or lower. .. When the molding temperature is in the above range, the second vinyl chloride resin is sufficiently melted while being suppressed from thermal decomposition, and good fluidity of the non-foamable resin composition can be obtained.
The molding temperature of the heat-melted foamable resin composition is preferably 170 ° C. or higher and 190 ° C. or lower, and more preferably 180 ° C. or higher and 190 ° C. or lower. When the molding temperature is in the above range, the first vinyl chloride resin is sufficiently melted while being suppressed from thermal decomposition, and good fluidity of the foamable resin composition can be obtained. The molding temperature of the heat-melted foamable resin composition may be the same as or different from the molding temperature of the non-foaming resin composition.
The time for molding with a mold is preferably 1 to 10 minutes. If it is at least the lower limit value, it can be sufficiently cured, and if it is at least the lower limit value, overfoaming can be suppressed and the productivity of the resin pipe joint can be easily improved.

Although the resin pipe joint of the present invention has been described above with reference to the drawings, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the spirit of the present invention.
The number of openings formed at both ends of the main body of the resin pipe joint is not limited to two, and may be three, four, or five or more. The inner diameter of the opening may be the same as or different from the inner diameter of the other openings.
The cross section of the main body of the resin pipe joint cut along a plane perpendicular to the pipe axis direction may be circular in a plan view, elliptical in a plan view, or polygon in a plan view.
Examples of the shape of the resin pipe joint include nipples, nipples with different diameters (resusers), cheese (tea), cloths, valve sockets, and the like in addition to the elbows described above.

Since the resin pipe joint of the present invention has a foam layer in the main body, it has excellent heat insulating properties. Since the resin pipe joint of the present invention uses the first vinyl chloride resin and the second vinyl chloride resin as raw materials, it has excellent chemical resistance. Further, the foamed layer and the non-foamed layer of the resin pipe joint of the present invention substantially do not contain lead, and the non-foamed layer is transparent or translucent. Therefore, the receiving part of the resin pipe joint is transparent or translucent, the inserted state of the pipe inside the joint can be confirmed, and it can be easily and surely visually recognized that the pipe is fixed to the receiving part of the joint. can do.

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 raw materials and evaluation methods used in each Example and Comparative Example are as follows. In addition, Example 3 is a reference example.

[Raw materials used]
<First vinyl chloride resin>
Polyvinyl chloride ( average degree of polymerization 640, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name "TS-640M").
<Second vinyl chloride resin>
Polyvinyl chloride ( average degree of polymerization 640, manufactured by Tokuyama Sekisui Kogyo Co., Ltd., trade name "TS-640M").
<foaming agent>
ADCA (manufactured by Otsuka Chemical Co., Ltd., trade name "AZ-HM", azodicarbonamide).
Baking soda (manufactured by Eiwa Kasei Kogyo Co., Ltd., trade name "Cerbon SC-855").
<First stabilizer>
Tin-based stabilizer (manufactured by Daikyo Kasei Co., Ltd., trade name "STX-80I").
CaZn-based stabilizer (manufactured by Sakai Chemical Co., Ltd., trade name "LHR-503").
Lead-based stabilizer (manufactured by Sakai Chemical Co., Ltd., trade name "TL-7000").
<Second stabilizer>
Tin-based stabilizer (manufactured by Daikyo Kasei Co., Ltd., trade name "STX-80I").
Lead-based stabilizer (manufactured by Sakai Chemical Co., Ltd., trade name "TL-7000").

[Examples 1 to 4, Comparative Examples 1 to 4]
A foamable resin composition in which a first vinyl chloride resin, a foaming agent, and a first stabilizer are mixed, and a non-mixed vinyl chloride resin and a second stabilizer in the formulation shown in Table 1. The foamable resin composition was injection-molded to produce a resin pipe joint having a foamed layer and a non-foamed layer. The shape of the resin pipe joint was an elbow. The molding temperature of the non-foamable resin composition was 170 ° C., the mold temperature of the non-foamable resin composition was 40 ° C., and the molding time was 120 seconds. The molding temperature of the foamable resin composition was 170 ° C., the mold temperature of the foamable resin composition was 40 ° C., and the molding time was 120 seconds.
The main body of the obtained resin pipe joint is non-transparent white, and the first receiving part and the second receiving part are translucent white. The presence or absence of discoloration at the interface (foam layer interface) and the presence or absence of discoloration of the foam layer were evaluated, and the determination was made according to the following criteria. ◎ ~ ○ was considered good. The results are also shown in Table 1.
[criterion]
⊚: There is no discoloration at the interface of the foam layer and no discoloration of the foam layer.
◯: There is no discoloration at the interface of the foam layer, but the foam layer is discolored.
Δ: There is discoloration at the interface of the foam layer, and there is no discoloration of the foam layer.
X: There is discoloration at the interface of the foam layer, and there is also discoloration of the foam layer.

[Confirmation of tin, lead, and zinc derived from stabilizers]
Each element of tin, lead and zinc in the foamed layer and the non-foamed layer was measured by ICP emission spectroscopic analysis.
About 0.05 g of a sample was collected from the central portion of the foamed layer or the non-foamed layer, and the mass of the sample was precisely weighed. Next, the sample was dissolved in a closed system using 6 mL of nitric acid, 1 mL of hydrogen peroxide was further added, dissolved in pure water, transferred to a 50 mL volumetric flask, and the volume was adjusted to 50 mL using pure water. A sample solution was prepared. ICP measurement was performed using the obtained sample solution under the conditions described below, and among the elements measured for the foamed layer and the non-foamed layer, the elements whose content (ppm) in the sample solution was 100 ppm or more are shown in Table 1. did.

<ICP measurement conditions>
Measuring device: SII Nanotechnology SPS5100.
Measuring element (lead): Wavelength 220.353 nm.
Measuring element (zinc): Wavelength 206.191 nm.
Measuring element (tin): Wavelength 283.998 nm.
High frequency output: 1.2 kW.
Carrier gas flow rate: 0.9 L / min.
Plasma flow rate: 15 L / min.
Auxiliary flow rate: 1.5 L / min.

As shown in Table 1, in Examples 1 and 2 in which the tin-based stabilizer was used for both the foamed layer and the non-foamed layer, the judgment result was "◎", and it was found that the transparency of the resin pipe joint was guaranteed. .. In Examples 3 and 4 in which the first stabilizer was changed to a CaZn-based stabilizer, the determination result was "⊚" or "◯".
On the other hand, in Comparative Examples 1 and 2 in which the first stabilizer was changed to a lead-based stabilizer and Comparative Examples 3 to 4 in which the second stabilizer was changed to a lead-based stabilizer, the judgment results were "x" to "Δ". It was found that the transparency of the resin pipe joint was not guaranteed.

According to the present invention, it has been found that a resin pipe joint having excellent heat insulating properties and chemical resistance and having a good appearance can be provided.

1 Resin pipe fitting 10 Main body 12a, 12b Opening 20a, 20b Receiving part 30 Foam layer 50 Non-foam layer

Claims (4)

In a resin pipe joint provided with a main body portion having a flow path inside and openings formed at both ends, and a receiving portion surrounding the peripheral edge of the opening of the main body portion.
The main body includes a foam layer and a non-foam layer that covers both sides of the foam layer.
The foamed layer is formed by foaming and molding a foamable resin composition containing a first vinyl chloride resin, an organic foaming agent, and a first stabilizer.
The non-foaming layer is formed by molding a non-foaming resin composition containing a second vinyl chloride resin and a second stabilizer.
The foamed layer and the non-foamed layer are substantially lead-free and do not contain lead.
The first stabilizer and the second stabilizer are tin-based stabilizers.
The non-foamed layer is a transparent or translucent resin pipe joint. In a resin pipe joint provided with a main body portion having a flow path inside and openings formed at both ends, and a receiving portion surrounding the peripheral edge of the opening of the main body portion.
The main body includes a foam layer and a non-foam layer that covers both sides of the foam layer.
The foamed layer is formed by foaming and molding a foamable resin composition containing a first vinyl chloride resin, an inorganic foaming agent, and a first stabilizer.
The non-foaming layer is formed by molding a non-foaming resin composition containing a second vinyl chloride resin and a second stabilizer.
The foamed layer and the non-foamed layer are substantially lead-free and do not contain lead.
The first stabilizer is a CaZn-based stabilizer or a tin-based stabilizer.
The second stabilizer is a tin-based stabilizer.
The non-foamed layer is a transparent or translucent resin pipe joint. The resin pipe joint according to claim 1 or 2, wherein the tin-based stabilizer is an organic acid salt of alkyl tin having an octyl group. The first vinyl chloride resin has an average degree of polymerization of 600 to 700, and has an average degree of polymerization of 600 to 700.
The resin pipe joint according to any one of claims 1 to 3, wherein the second vinyl chloride resin has an average degree of polymerization of 600 to 700.

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