JP2022048587A - Pipe fitting, piping structure, and method of manufacturing pipe fitting - Google Patents

Abstract

To provide a pipe fitting with a high melt mass flow rate value, good formability, and excellent chemical resistance, its manufacturing method, and a piping structure using this pipe fitting.SOLUTION: A pipe fitting 1 having receiving portions 20a, 20b, 20c into which a pipe member is inserted, and a flow passage connecting the plurality of receiving portions is formed inside, at least a portion in contact with the flow passage is composed of a resin composition (I). The resin composition (I) contains vinyl cyanide monomer units, diene monomer units, aromatic vinyl monomer units, and methacrylic monomer units, and the methacrylic monomer unit content, as determined by PGC/MS, is 30 mass percent or less and a total content of vinyl cyanide monomer units and methacrylic monomer units is 35 to 80 mass percent.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pipe joint, a pipe structure, and a method for manufacturing a pipe joint.

Conventionally, it is common to prevent dew condensation around the pipe by covering the circumference of the pipe made of a steel pipe or a synthetic resin pipe 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 possible in a narrow work space.
Therefore, a resin pipe member or a pipe joint having a foamed resin layer as a heat insulating layer has 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 tube 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. In Patent Document 1, polymethylmethacrylate is kneaded into a copolymer containing a rubber component having excellent impact resistance, a vinyl cyanide-based monomer unit, and an aromatic vinyl-based monomer unit, and further, a foaming agent. It is described that a pipe joint in which the surface of the foamed resin layer is covered with a non-foamed resin layer is manufactured by injection molding the resin to which the above is added.
As described in Patent Document 1, when an acrylic resin such as polymethyl methacrylate is blended, the pipe joint can be made transparent, and the connection state between the pipe member and the pipe joint can be easily visually recognized.

Japanese Patent No. 6581749

However, as a result of further studies by the present inventor, a resin composition in which methyl polymethacrylate is blended with a copolymer containing a rubber component, a vinyl chloride-based monomer unit, and an aromatic vinyl-based monomer unit has been obtained. It has been found that when a pipe joint is manufactured using it, the melt mass flow rate is lowered and the formability may be hindered.
If the temperature is raised, it becomes easier to secure the fluidity required for molding. However, when the non-foaming resin layer is formed on the surface of the foaming resin layer by injection molding the resin to which the foaming agent is added, if the temperature is too high, the foaming cannot be controlled and the surface does not become the non-foaming resin layer. ..

Further, since the pipe joint comes into contact with various fluids, chemical resistance is required at least in the portion in contact with the flow path.
The present invention has been made in view of the above circumstances, and uses a pipe joint having a high melt mass flow rate value, good moldability, and excellent chemical resistance, a method for manufacturing the same, and the pipe joint. The subject is to provide a piping structure.

In order to achieve the above problems, the present invention has adopted the following configuration.
[1] A pipe joint having a plurality of receiving portions into which a pipe member is inserted and having a flow path in which the plurality of receiving portions are communicated with each other.
At least, the portion in contact with the flow path is made of the resin composition (I).
The resin composition (I) contains a vinyl cyanide-based monomer unit, a diene-based monomer unit, an aromatic vinyl-based monomer unit, and a methacrylic-based monomer unit.
The content of the methacrylic monomer unit determined by pyrolysis gas chromatography-mass spectrometry (PGC / MS) is 30% by mass or less with respect to the entire resin component of the resin composition (I).
The total content of the vinyl cyanide-based monomer unit and the methacrylic-based monomer unit determined by the pyrolysis gas chromatography mass spectrometry (PGC / MS) is applied to the entire resin component of the resin composition (I). On the other hand, a pipe joint having 35 to 80% by mass.
[2] The content of the aromatic vinyl-based monomer unit determined by pyrolysis gas chromatography-mass spectrometry (PGC / MS) is 30 mass with respect to the entire resin component of the resin composition (I). % Or less, according to [1].
[3] The pipe fitting according to [1] or [2], wherein the resin composition (I) contains acrylic rubber.
[4] According to JIS K 7210: 1999 of the resin composition (I), the melt mass flow rate measured at a test temperature of 220 ° C. and a test load of 9.8 N is 5 g / 10 minutes or more, [1] to [ 3] The pipe fitting according to any one of the items.
[5] A surface layer composed of the resin composition (I) and a foamed resin layer covered with the surface layer are provided, and the surface layer has a foaming ratio of 1.0 times or more and less than 1.1 times. The pipe joint according to any one of [1] to [4], wherein the foamed resin layer has a foaming ratio of 1.1 times or more.
[6] A piping structure comprising the pipe fitting according to any one of [1] to [5] and a pipe member inserted and connected to the receiving portion of the pipe joint.
[7] The method for manufacturing a pipe joint according to any one of [1] to [6], wherein a foaming agent is mixed with the powder or pellet of the resin composition (I) to form an effervescent resin composition. A method for manufacturing a pipe joint, in which a product is obtained and the obtained foaming agent resin composition is injection-molded.
[8] The method for manufacturing a pipe joint according to [7], wherein the powder or pellet of the resin composition (I) is dried and then mixed with the foaming agent.

According to the pipe joint and the pipe structure of the present invention, the pipe joint and the pipe structure having excellent chemical resistance can be obtained. Further, according to the method for manufacturing a pipe joint of the present invention, a resin composition having a high melt mass flow rate and excellent moldability is used, so that the manufacturing is easy.

It is sectional drawing which shows the pipe joint which concerns on one Embodiment of this invention. It is a top view which shows the piping structure which concerns on one Embodiment of this invention.

[Structure of pipe fitting]
The pipe joint of the present invention has a plurality of receiving portions into which pipe members are inserted, and has a structure in which a flow path communicating with the plurality of receiving portions is formed inside.
The number of receiving portions is not limited, but is preferably two or three.
FIG. 1 shows a pipe joint 1 having three receiving portions according to an embodiment of the present invention.

As shown in FIG. 1, the pipe joint 1 of the present embodiment is a joint used for connecting a drain pipe (a three-way branch T-shaped pipe joint joint generally called "cheese"). Is taken as an example. The pipe joint 1 has a first pipe shaft O1 and a second pipe shaft O2. The two tube axes O1 and O2 intersect each other at an angle of 90.0 ° ± 1.1 °.
The pipe joint 1 has a tubular main body portion 10 having a flow path (for example, a drain flow path) formed therein, and three receiving portions 20a, 20b, and 20c integrally formed with the main body portion 10. ..

The main body 10 has a foamed resin layer 30 and a non-foamed resin layer 50. Both sides of the foamed resin layer 30 are covered with the non-foamed resin layer 50. That is, the wall of the main body 10 has a three-layer structure in which the non-foaming resin layer 50, the foamed resin layer 30, and the non-foaming resin layer 50 are located from the flow path side. The receiving portion 20a, the receiving portion 20b, and the receiving portion 20c are formed of a non-foamed resin layer 50. That is, the walls of the receiving portion 20a, the receiving portion 20b, and the receiving portion 20c have a single-layer structure formed of the non-foamed resin layer 50.
From the viewpoint of enhancing water stoppage, the receiving portions 20a, 20b, and 20c are preferably transparent. That is, the non-foamed resin layer 50 is preferably transparent from the viewpoint of facilitating confirmation of the connection state between the pipe joint 1 and the pipe member inserted and connected to the receiving portion thereof. Here, "transparent" means that the tube to be inserted and the adhesive applied to the inner surface of the receiving portion are transparent to the extent that they can be visually recognized from the outer surface of the receiving portion, and are translucent or colored. It may be transparent.
More specifically, the haze of the receiving portion measured according to JIS K 7136: 2000 is preferably 1 or more and 70 or less, and more preferably 1 or more and 60 or less.

Cylindrical receiving portions 20a and 20b are provided in the openings 10a and 10b formed at both ends of the main body portion 10 forming a straight pipe in the direction of the first pipe axis O1.
A cylindrical receiving portion 20c is provided in the opening portion 10c formed in the direction of the second pipe shaft O2 of the main body portion 10.
In the main body 10, an injection gate portion 14 is provided at a position facing the opening 10c with the first pipe shaft O1 interposed therebetween, which is a position to be ejected at the time of molding.

The inner diameter R _20a of the receiving portion 20a has a larger diameter than the inner diameter R _10a of the opening 10a of the main body portion 10 in order to insert and connect the pipe member with the foamed resin layer. Specifically, the ratio R _20a / R _10a is preferably more than 1.0 and 2.0 or less, more preferably 1.2 or more and 1.8 or less, and further preferably 1.4 or more and 1.6 or less.
Similarly, the inner diameter R _20b of the receiving portion 20b has a larger diameter than the inner diameter R _10b of the opening portion 10b of the main body portion 10. Specifically, the ratio R _20b / R _10b is preferably more than 1 and 2.0 or less, more preferably 1.2 or more and 1.8 or less, and further preferably 1.4 or more and 1.6 or less.
Similarly, the inner diameter R _20c of the receiving portion 20c has a larger diameter than the inner diameter R _10c of the opening portion 10c of the main body portion 10. Specifically, the ratio R _20c / R _10c is preferably more than 1 and 2.0 or less, more preferably 1.2 or more and 1.8 or less, and further preferably 1.4 or more and 1.6 or less.

At the boundary between the receiving portion 20a and the main body portion 10, a step 12a based on the difference between the inner diameter R _20a and the inner diameter R _10a is formed. The step 12a functions as a stopper for preventing the intrusion of the pipe member inserted into the receiving portion 20a.
At the boundary between the receiving portion 20b and the main body portion 10, a step 12b based on the difference between the inner diameter R _20b and the inner diameter R _10b is formed. The step 12b functions as a stopper for preventing the intrusion of the pipe member inserted into the receiving portion 20b.
At the boundary between the receiving portion 20c and the main body portion 10, a step 12c based on the difference between the inner diameter R _20c and the inner diameter R _10c is formed. The step 12c functions as a stopper for preventing the intrusion of the pipe member inserted into the receiving portion 20c.

The step 12a is formed by a peripheral wall 13 located on the peripheral edge of the opening 10a of the main body 10. The peripheral wall 13 is formed over the entire circumference of the inner peripheral surface of the cylindrical receiving portion 20a, and is annular.
The step 12b is formed by a peripheral wall 13 located on the peripheral edge of the opening 10b of the main body 10. The peripheral wall 13 is formed over the entire circumference of the inner peripheral surface of the cylindrical receiving portion 20b, and is annular.
The step 12c is formed by a peripheral wall 13 located on the peripheral edge of the opening 10c of the main body 10. The peripheral wall 13 is formed over the entire circumference of the inner peripheral surface of the cylindrical receiving portion 20c, and is annular.

The peripheral wall 13 is solid. The inside of the peripheral wall 13 is composed of the foamed resin layer 30, and the foamed resin layer 30 is covered with the non-foamed resin layer 50.
It is preferable that the foamed resin layer 30 is formed on the peripheral wall 13 over the entire circumference. When the foamed resin layer 30 is formed over the entire circumference of the peripheral wall 13, the heat insulating property is also provided at the base ends of the receiving portions 20a, 20b, and 20c, and the heat insulating property of the pipe joint 1 can be further enhanced.
When the pipe member inserted into the receiving portion 20a, 20b, or 20c includes a foamed resin layer, it is preferable to provide an annular water blocking member between the end face of the pipe member and the peripheral wall 13. Examples of the annular waterproof member include foamed packing and the like.

When the foamed resin layer of the pipe member is an open cell, it is preferable to provide an annular water blocking member between the end face of the pipe member and the peripheral wall 13. By providing the water blocking member, it is possible to prevent drain water from entering the foamed resin layer of the pipe member.
When the foamed resin layer of the pipe member is a closed cell, it is not necessary to provide a water blocking member between the end face of the pipe member and the peripheral wall 13. However, when the pipe member is cut diagonally, drain water may stay between the end surface of the pipe member and the peripheral wall 13, so it is preferable to provide a water stop member.

The receiving portion 20a extends from the base end 21a in the direction of the first pipe axis O1. The base end 21a is at the boundary between the receiving portion 20a and the main body portion 10. The length from the base end _21a of the receiving portion 20a to the opening end 22a is La. The length La is equal to the receiving length of the receiving portion _20a . The thickness of the receiving portion _20a at the opening end 22a is da. The thickness da is equal to the socket thickness of the socket _20a .
The receiving portion 20b extends from the base end 21b in the direction of the first pipe axis O1. The base end 21b is at the boundary between the receiving portion 20b and the main body portion 10. The length from the base end 21b of the receiving portion 20b to the opening end 22b is L _b . The length L _b is equal to the socket length of the socket portion 20b. The thickness of the receiving portion 20b at the opening end 22b is _db . The thickness _db is equal to the socket thickness of the socket portion 20b.
The receiving portion 20c extends from the base end 21c in the direction of the second pipe axis O2. The base end 21c is at the boundary between the receiving portion 20c and the main body portion 10. The length from the base end 21c of the receiving portion 20c to the opening end 22c is L _c . The length L _c is equal to the socket length of the socket portion 20c. The thickness of the receiving portion _20c at the opening end 22c is dc. The thickness d _c is equal to the socket thickness of the socket 20c.

The ratio of the length La from the base end 21a of the receiving portion 20a to the opening end 22a and the thickness da _a of the receiving portion 20a at the opening end 22a (hereinafter, also referred to as “ _La / _{da a ratio} ”). ) Is 2.0 or more and 10.0 or less, preferably 2.0 or more and 9.0 or less, more preferably 2.5 or more and 8.0 or less, and even more preferably 3.0 or more and 7.0 or less. It is particularly preferable that it is 5.5 or more and 6.0 or less.
When the La / _{da a ratio} is at least the above lower limit value, it is easy to suppress the invasion of the foamed resin layer 30 into the receiving portion 20a, and it is easy to suppress the decrease in the strength of the receiving portion 20a. In addition, when the La / _{da a ratio} is equal to or higher than the above lower limit value, the length La of the receiving portion _20a is sufficiently long, so that the adhesive force of the pipe member or the like to be inserted into the pipe joint 1 is sufficient and the stopper is stopped. More water-based.

When the La / _{da a ratio} is not more than the above upper limit value, the thickness _da is sufficiently thick, and the pipe joint 1 is less likely to be broken due to expansion and contraction fatigue due to expansion and contraction. In addition, when the _La / _da ratio is not more than the above upper limit value, the length _La is not too long, and the resin forming the receiving portion 20a is likely to be filled up to the end portion in the mold, resulting in insufficient filling ( Molding defects due to (also called "short") are less likely to occur. That is, when the La / _da ratio is not more than the above upper limit value, the _formability of the pipe joint 1 can be further improved.
The _La / _da ratio can be adjusted by the shape of the molding die.
The L _b / _db ratio in the receiving portion 20b of the pipe joint 1 is the same as the La / _{da a ratio} .
The L _c / _{d c} ratio in the receiving portion 20 c of the pipe joint 1 is the same as the La / d _a ratio.

The thermal resistance value of the main body 10 is preferably 0.04 K / W or more, more preferably 0.05 K / W or more and 0.50 K / W or less, and further preferably 0.06 K / W or more and 0.45 K / W or less. 0.07K / W or more and 0.40K / W or less are particularly preferable, and 0.08K / W or more and 0.35K / W or less are most preferable. When the thermal resistance value of the main body 10 is at least the above lower limit value, the heat insulating property of the pipe joint 1 can be further improved. When the thermal resistance value of the main body portion 10 is not more than the above upper limit value, the strength of the main body portion 10 is sufficient, and in addition, the pipe joint 1 can be made lightweight.
By lowering the thermal conductivity of the main body 10 or increasing the thickness (thickness) of the main body 10 depending on the composition and type of the resin constituting the pipe joint 1, the molding conditions of the pipe joint 1, etc. The thermal resistance value of the main body 10 can be increased.

The outer diameter of a general drain pipe is 30 mm to 80 mm, and the wall thickness is about 5 mm to 10 mm. The wall thickness of the main body of the pipe joint 1 used for connecting such a drain pipe is 8 mm or more and 20 mm. It is said to be as follows.
The thermal resistance value of the main body 10 is the thermal conductivity (W / m · K) measured in accordance with JIS A 1412-1: 2016 and the thickness (m) of the main body 10 at the measurement point of the thermal conductivity. From, it is calculated by the following formula (1).
Thermal resistance value (K / W) = thickness (m) / thermal conductivity (W / m · K) ... (1)

The pipe joint of the present invention is not limited to the pipe joint 1 described above, and may be a pipe joint having another shape such as an elbow, a nipple, or a valve socket.

In the pipe joint of the present invention, at least a portion in contact with the flow path is made of the resin composition (I) described later. In the case of the pipe joint 1, the inner surface of the main body portion 10 and the inner surfaces of the three receiving portions 20a, 20b, and 20c are in contact with the flow path, and are composed of the resin composition (I).
For convenience of manufacture, the pipe joint of the present invention preferably has the entire non-foamed resin layer 50 as a surface layer composed of the resin composition (I).
The composition of the monomer unit of the resin composition constituting the foamed resin layer 30 may be the same composition as that of the resin composition (I) or a different composition, but is equivalent to the resin composition (I) for convenience of production. Is preferable.

The surface layer composed of the resin composition (I) preferably has a foaming ratio of 1.0 times or more and less than 1.1 times. That is, it is preferable that the foam is not foamed, or even if it is foamed, the foaming ratio is low. This makes it difficult for the fluid in the flow path to enter the inside of the pipe joint material. The expansion ratio of the surface layer composed of the resin composition (I) is more preferably 1.0 times or more and 1.05 times or less.

Further, the foaming ratio of the foamed resin layer 30 covered with the non-foamed resin layer 50 which is the surface layer is preferably 1.1 times or more, more preferably 1.1 times or more and 5.0 times or less. . 2 times or more and 3.0 times or less are more preferable.
When the foaming ratio of the foamed resin layer 30 is at least a preferable lower limit value, a heat insulating effect is produced, and it becomes easy to prevent dew condensation and the like. The strength can be increased by setting the foaming ratio of the foamed resin layer 30 to be not more than a preferable upper limit value.
The foaming ratio is measured according to the method of 6.2 (a) or 6.2 (b) described in JIS K 9798: 2006. 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.

In the foamed resin layer 30, a plurality of bubbles are formed, substantially no pores are present in the bubble wall, and at least a part of the plurality of bubbles is a closed cell that does not communicate with each other. Is preferable.
The closed cell ratio is preferably 85% or more, more preferably 90% or more. The upper limit is not particularly limited, but is substantially 99% or less. Within the above numerical range, low thermal conductivity can be maintained for a long period of time, and the heat insulating property is excellent.
The closed cell ratio is measured according to JIS K 7138: 2006.

[Resin composition (I)]
The resin composition (I) in the present invention contains a vinyl cyanide-based monomer unit, a diene-based monomer unit which is a rubber component, an aromatic vinyl-based monomer unit, and a methacrylic monomer unit. .. That is, the resin composition (I) in the present invention is a copolymer containing these monomer units, or is a polymer of two or more kinds or a mixture of copolymers.

In the present specification, the "monomer unit" refers to a structural portion derived from a monomer compound (monomer) before polymerization, and for example, the "vinyl cyanide-based monomer unit" is "cyanylated." It refers to the structural part derived from (vinyl monomer).
The content ratio of each monomer unit in the resin composition is the ratio of the monomer in the monomer mixture used for producing one kind of copolymer contained in the resin composition, or the ratio of each of the plurality of polymers. Corresponds to the total ratio of the monomers used in the production of.

Examples of the vinyl cyanide-based monomer unit include a monomer unit based on acrylonitrile, meta-acrylonitrile, and the like. Of these, a monomer unit based on acrylonitrile is preferable.
Examples of the aromatic vinyl-based monomer unit include monomer units based on styrene, α-methylstyrene, β-methylstyrene, 4-methylstyrene, β-bromostyrene and the like. Of these, monomer units based on styrene and α-methylstyrene are preferable.
Examples of the methacrylic monomer unit include a monomer unit based on methyl methacrylate, ethyl methacrylate, glycidyl methacrylate and the like. Of these, a monomer unit based on methyl methacrylate is preferable.

Examples of the diene-based monomer unit as the rubber component include monomer units based on 1,3-butadiene, isoprene, 1,3-pentadiene, chloroprene, 2-ethylbutadiene, 2-phenylbutadiene and the like. Of these, monomeric units based on 1,3-butadiene, isoprene, 1,3-pentadiene, and 2-phenylbutadiene are preferable.

In the present specification, the content of each monomer unit in the resin composition is a corresponding single amount obtained by analysis using a pyrolysis gas chromatography mass spectrometry method (hereinafter, also referred to as “PGC / MS”). It is a content based on the mass of the body.
An example of measurement conditions using PGC / MS is shown below.
(Measurement condition)
-Pyrolysis device: PY-2020iD (Frontier Lab Co., Ltd.).
Gas chromatograph: GC 2010 (Shimadzu Corporation).
Mass spectrometer: GCMS-QP 2010 (Shimadzu Corporation).
-Pyrolysis conditions Pyrolysis temperature: 550 ° C.
Interface temperature: 250 ° C.
-Gas chromatograph conditions.
Carrier flow rate: 1 ml / min (He).
Split ratio: 100: 1.
Separation column: DB-1 (1.00 μm, 0.25 mmφ × 30 m).
Oven temperature: 40 ° C (3 min) -320 ° C (10 min).
-Mass spectrometry conditions Interface temperature: 250 ° C.
Ionization temperature: 220 ° C.
Mass range: 28-700 m / z.
Voltage: 1.2kV.

A method of calculating the content of each monomer unit in the resin composition by measuring PGC / MS will be described.
First, each monomer unit constituting the resin composition is thermally decomposed and separated by pyrolysis gas chromatography, and the monomer from which each monomer unit is derived is recorded as a peak thermal decomposition pattern (pyrogram). To get. Next, for each peak of the pyrolysis pattern, which monomer is specified by the mass spectrum obtained by the mass spectrometer.

Here, since the depolymerization rate by thermal decomposition (the rate at which the polymer decomposes into monomers) differs depending on the type of the monomer unit, the area (X) of each peak in the pyrogram is set to each unit amount by thermal decomposition. The peak area (Z) of each monomer is obtained by dividing by the depolymerization rate (Y) of each body unit. The depolymerization rate (Y) of each monomer unit is a monomer unit based on acrylonitrile, which is a vinyl cyanide-based monomer unit: 0.15, and a monomer unit based on a diene-based monomer unit: 0. 10. Monomer unit based on styrene, which is an aromatic vinyl-based monomer unit: 1.0. Further, the depolymerization rate of the monomer unit based on methyl methacrylate, which is a methacrylic monomer unit, is 1.0 when it exists as a resin such as polymethyl methacrylate before thermal decomposition. Further, the depolymerization rate of the monomer unit based on the acrylic acid ester, which is an acrylic rubber, is 1.0 when it exists as a copolymer resin of the acrylic acid ester before thermal decomposition.

Then, the ratio (Z / T) of the peak area (Z) of each component of the thermal decomposition pattern to the total (T) is defined as the content (mass%) of the monomer unit in the resin composition.
That is, the content of each monomer unit in the entire resin component in the present invention is the ratio of the mass of each monomer to the total mass of all the monomers constituting the resin composition.

The content of the methacrylic monomer unit in the entire resin component of the resin composition (I) is 30% by mass or less, preferably 0.1 to 30% by mass, and 0.5 to 28% by mass. It is more preferably present, and even more preferably 0.5 to 22% by mass.
When the content of the methacrylic monomer unit is 30% by mass or less, a resin composition having a high melt mass flow rate and good moldability can be obtained. When the content of the methacrylic monomer unit is at least the preferable lower limit value, transparency can be easily obtained.

The total content of the vinyl cyanide-based monomer unit and the methacrylic-based monomer unit in the entire resin component of the resin composition (I) is 35 to 80% by mass, preferably 40 to 80% by mass. , 45-80% by mass, more preferably 45-75% by mass.
When the total content of the vinyl cyanide-based monomer unit and the methacrylic monomer unit is 35% by mass or more, chemical resistance can be obtained. When the total content of the vinyl cyanide-based monomer unit and the methacrylic monomer unit is 80% by mass or less, a resin composition having a high melt mass flow rate and good moldability can be obtained.

The content of the vinyl cyanide-based monomer unit in the entire resin component of the resin composition (I) is preferably 5 to 70% by mass, more preferably 30 to 70% by mass, and 40 to 70. It is more preferably by mass, and particularly preferably 50 to 70% by mass.
When the content of the vinyl cyanide-based monomer unit is at least the preferable lower limit value, good chemical resistance can be easily obtained. When the content of the vinyl cyanide-based monomer unit is not more than the preferable upper limit value, good impact resistance can be easily obtained.

The content of the diene-based monomer unit in the entire resin component of the resin composition (I) is preferably 5 to 40% by mass, more preferably 15 to 35% by mass, and 30 to 35% by mass. Is more preferable.
When the content of the diene-based monomer unit is at least the preferable lower limit value, good impact resistance can be easily obtained. When the content of the diene-based monomer unit is not more than the preferable upper limit value, it is easy to obtain good chemical resistance.

The resin composition (I) preferably contains acrylic rubber.
Examples of the acrylic rubber include acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, which are vinyl cyanide-based monomer units, diene-based monomer units, or tacryl-based monomer units. It may be contained in the resin composition (I) as a copolymer with.
The content of acrylic rubber in the entire resin component of the resin composition (I) is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, and 0.5 to 1%. It is more preferably by mass%.
When the content of acrylic rubber is at least the preferable lower limit, the affinity with other monomer units is enhanced, and even if the content of the diene-based monomer unit, which is a rubber component, is high, chemical resistance is ensured. It's easy to do. When the content of acrylic rubber is not more than a preferable upper limit value, good moldability can be easily obtained.

The content of the aromatic vinyl-based monomer unit in the entire resin component of the resin composition (I) is preferably 5 to 30% by mass, more preferably 5 to 20% by mass, and 5 to 13%. It is more preferably by mass%.
When the content of the aromatic vinyl-based monomer unit is at least the preferable lower limit value, the melt mass flow rate can be easily increased and the moldability can be further improved. When the content of the aromatic vinyl-based monomer unit is not more than the preferable upper limit value, it is easy to obtain better chemical resistance.

The resin composition (I) contains a vinyl cyanide-based monomer unit, a diene-based monomer unit, an aromatic vinyl-based monomer unit, and a methacrylic monomer unit, as long as the effects of the present invention are not impaired. Other monomer units other than the above may be contained.
Examples of other monomer units include N-phenylmaleimide and glycidyl methacrylate.
The content of other monomer units in the entire resin component of the resin composition (I) is preferably less than 5% by mass, more preferably less than 1% by mass.
That is, the total content of the vinyl cyanide-based monomer unit, the diene-based monomer unit, the aromatic vinyl-based monomer unit, and the methacrylic monomer unit in the entire resin component of the resin composition (I). The amount is preferably 95% by mass or more, more preferably 99% by mass or more.

The resin composition (I) may contain a component other than the monomer unit, that is, a component other than the resin component, as long as the effect of the present invention is not impaired.

According to JIS K 7210: 1999 of the resin composition (I), the melt mass flow rate (hereinafter, also referred to as “MFR”) measured at a test temperature of 220 ° C. and a test load of 9.8 N (test load: 10 kg) is 5 g / 10 Minutes or more is preferable, 5 g / 10 minutes or more and 90 g / 10 minutes or less is preferable, 10 g / 10 minutes or more and 80 g / 10 minutes or less is more preferable, 15 g / 10 minutes or more and 70 g / 10 minutes or less is further preferable, and 20 g. It is particularly preferable that it is at least / 10 minutes and 60 g / 10 minutes or less.

When the MFR of the resin composition (I) is at least the above lower limit value, it is easy to fill the resin up to the end in the mold when manufacturing the pipe joint 1, and molding due to insufficient filling, which tends to occur especially at the receiving portion. Defects are unlikely to occur. That is, when the MFR of the pipe joint 1 is at least the above lower limit value, the moldability of the pipe joint 1 can be further improved. When the MFR of the pipe joint 1 is not more than the above upper limit value, the molecular weight is not too low, and the strength and chemical resistance are excellent.

Preferred embodiments of the resin composition (I) include, for example, the following examples.
A: A resin composition in which a copolymer obtained by polymerizing methyl methacrylate on an ABS resin and an acrylic rubber made of an acrylic acid ester or an acrylic rubber made of a copolymer of an acrylic acid ester and methyl methacrylate are mixed.
B: A resin composition in which an ABS resin and an acrylic rubber made of a copolymer of styrene and methyl methacrylate and an acrylic acid ester or an acrylic rubber made of a copolymer of an acrylic acid ester and methyl methacrylate are mixed.
C: A resin composition obtained by mixing ABS resin, acrylic rubber made of acrylic acid ester, or acrylic rubber made of a copolymer of acrylic acid ester and methyl methacrylate.
D: A resin composition obtained by mixing methyl polymethacrylate with a copolymer of acrylonitrile, butadiene, styrene, and an acrylic acid ester.
The ABS resin may be a resin composition obtained by physically mixing a copolymer of acrylonitrile-styrene-methyl methacrylate and polybutadiene, and the polybutadiene may be mixed with methyl methacrylate, styrene and acrylonitrile. It may be a resin grafted with, or it may be a resin obtained by emulsifying and polymerizing four kinds of monomers constituting acrylonitrile, butadiene, methyl methacrylate and styrene.

[Manufacturing method of pipe fittings]
The method for manufacturing a pipe joint according to the present invention is a method in which a foaming agent is mixed with a powder or pellet of the resin composition (I) to obtain a foaming resin composition, and the obtained foaming agent resin composition is injection-molded. be.
The inside of the molded product obtained by this method becomes a foamed resin layer by heating during injection molding, but the surface layer becomes a so-called skin layer having a low foaming ratio, that is, a non-foamed resin layer.

It is preferable that the powder or pellet of the resin composition (I) is dried in advance and then mixed with a foaming agent.
By drying the foaming agent before mixing it, the moisture evaporated in the molding machine suppresses the generation of unintended air bubbles inside and on the surface of the joint, reducing the transparency of the socket and the strength of the main body. Can be suppressed. Examples of the drying method include a method using a hot air dryer such as a hopper dryer or a box-shaped drying furnace. The temperature of hot air drying is preferably 60 to 90 ° C., and the drying time is preferably 2 to 6 hours.

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 the aliphatic hydrocarbon include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), and examples of the alicyclic hydrocarbon include cyclopentane, cyclohexane, and the like. Can be mentioned. Examples of the halogenated hydrocarbon include one or more 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), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds, and sodium borohydride, azodicarboxylic amide, and barium azodicarboxylate. Examples thereof include organic foaming agents such as 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 blending amount of the foaming agent is preferably 0.1 part by mass or more and 8 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, and 1 part by mass or more with respect to 100 parts by mass of the resin composition (I). 3 parts by mass or less is more preferable.

In injection molding, the temperature (molding temperature) of the foamable resin composition immediately before being injected into the mold is preferably 200 ° C. or higher and 280 ° C. or lower, and more preferably 220 ° C. or higher and 260 ° C. or lower. When the molding temperature is within the above numerical range, the foamable resin composition is sufficiently melted, and good fluidity of the foamable resin composition can be obtained. Further, when the foamable resin composition contains an acrylic resin, the transparency of the pipe joint 1 can be enhanced by setting the molding temperature to be equal to or higher than the above lower limit value.
The time for molding with the mold is preferably 1 minute or more and 10 minutes or less. When the time for molding with the mold is equal to or longer than the above lower limit, the foamable resin composition can be sufficiently cured. When the time for molding with the mold is not more than the above upper limit value, the productivity of the pipe joint 1 is likely to be improved.

The pipe joint according to the present invention may be manufactured by a manufacturing method other than the above manufacturing method. For example, a foaming agent may be mixed with the powder or pellet of the resin composition (I) to obtain a foamable resin composition, and the obtained foaming agent resin composition may be extruded.
In the case of extrusion molding, the foamable resin composition is heated and melted, injected into a mold from an extruder, and heated at an arbitrary temperature for an arbitrary time to foam and mold the foamable resin composition. After cooling at an arbitrary temperature for an arbitrary time, a pipe joint having a predetermined expansion ratio can be obtained by cutting to a predetermined length.
The inside of the molded product obtained by this method becomes a foamed resin layer by heating during extrusion molding, but the surface layer becomes a so-called skin layer having a low expansion ratio, that is, a non-foamed resin layer.
In the case of extrusion molding as well as in the case of injection molding, it is preferable that the powder or pellet of the resin composition (I) is pre-dried and then mixed with a foaming agent.

The pipe joint according to the present invention may be manufactured by multi-layer molding in which a layer of a resin composition containing a foaming agent is sandwiched between layers composed of a pair of resin compositions (I) containing no foaming agent. Further, it may be produced by multi-layer molding in which a layer of the resin composition containing a foaming agent is laminated on one side (the side opposite to the flow path) of the layer composed of the resin composition (I) containing no foaming agent.
In the case of these multi-layer molding, the resin composition containing a foaming agent may be a foamable resin composition in which a foaming agent is mixed with the resin composition (I), or may be a resin composition different from the resin composition (I). A foamable resin composition mixed with a foaming agent may be used.
Further, it may be produced only with the resin composition (I) containing no foaming agent.

[Piping structure]
The piping structure of the present invention includes the pipe joint of the present invention and a pipe member that is inserted and connected to the receiving portion of the pipe joint.
The piping structure according to the embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 2, the pipe structure 100 includes a pipe joint 1 and three pipe members 201, 202, 203.
The pipe member is not particularly limited, and may be any pipe member that can be connected to the pipe joint of the present invention. The pipe member may be a steel pipe or a synthetic resin pipe. As the pipe member, a synthetic resin pipe is preferable, and a synthetic resin pipe having a foamed layer is more preferable, from the viewpoint of excellent heat insulating properties. The foam layer may be open cells in which bubbles are in communication with each other, or closed cells in which bubbles are not in communication with each other.

In the present embodiment, the pipe member 201 is inserted and connected to the receiving portion 20a of the pipe joint 1 along the direction of the first pipe shaft O1. The pipe member 202 is inserted and connected to the receiving portion 20b of the pipe joint 1 along the direction of the first pipe shaft O1. The pipe member 203 is inserted and connected to the receiving portion 20c of the pipe joint 1 along the direction of the second pipe shaft O2.
The outer diameter R ₂₀₁ of the pipe member 201 is slightly smaller than the inner diameter R _20a of the receiving portion 20a. The inner diameter R _20a of the receiving portion 20a referred to here means the inner diameter of the receiving end portion of the receiving portion 20a, and the ratio R ₂₀₁ / R _20a is preferably 0.986 to 0.997.
The outer diameter R ₂₀₂ of the pipe member 202 is slightly smaller than the inner diameter R _20b of the receiving portion 20b. The inner diameter R _20b of the receiving portion 20b referred to here means the inner diameter of the receiving end portion of the receiving portion 20b, and the ratio R ₂₀₂ / R _20b is preferably 0.986 to 0.997.
The outer diameter R ₂₀₃ of the pipe member 203 is slightly smaller than the inner diameter R _20c of the receiving portion 20c. The inner diameter R _20c of the receiving portion 20c referred to here means the inner diameter of the receiving end portion of the receiving portion 20c, and the ratio R ₂₀₃ / R _20c is preferably 0.986 to 0.997.

The pipe structure 100 functions as a pipe connection portion for draining the drain. In addition, the pipe structure 100 functions as a branch portion of the pipe for draining the drain.

[Manufacturing method of piping structure]
The method for manufacturing the pipe structure is not particularly limited, and the pipe structure of the present invention can be obtained by inserting and connecting a pipe member to the receiving portion of the pipe joint of the present invention. The method of connecting the pipe joint and the pipe member is not particularly limited, and may be connected by using an adhesive, and a rubber packing or the like is stopped between the inner surface of the receiving portion of the pipe joint and the outer surface of the pipe member. By installing a water member, it may be connected without using an adhesive.

In the pipe structure 100 of the present embodiment, the pipe joint 1 and the pipe members 201, 202, 203 are connected by using an adhesive. By connecting the pipe joint and the pipe member with an adhesive, the water stoppage and strength of the pipe structure can be further enhanced.
The adhesive used for connecting the pipe joint and the pipe member is not particularly limited, and examples thereof include known adhesives such as instant adhesives and hot melt adhesives.

Since the piping structure of the present embodiment includes the pipe joint of the present embodiment, it has excellent heat insulating properties.
In addition, the piping structure of the present embodiment is excellent in strength because it includes the pipe joint of the present embodiment.
Further, since the piping structure of the present embodiment includes the pipe joint of the present embodiment, it is excellent in water stopping property.

Next, the present invention will be described in more detail by way of 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.

[Example 1]
Obtained by heating and kneading an acrylonitrile monomer, a styrene monomer, polybutadiene (manufactured by Asahi Kasei Co., Ltd., Diene 35NF), a methyl methacrylate monomer, and butyl acrylate in the presence of a polymerization initiator. The resin composition was used as a non-foamable resin composition. At this time, the non-foamable resin composition was kneaded at a ratio such that the content of each monomer unit obtained by measuring with PGC / MS is as shown in Table 1.
This non-foaming resin composition was pelletized and dried at 70 ° C. for 2 hours using a known hot air dryer. A dry pellet-shaped non-foamable resin composition mixed with ADCA (manufactured by Otsuka Chemical Co., Ltd., trade name "AZ-HM", azodicarbonamide) as a foaming agent was used as a foamable resin composition.
A predetermined amount of the obtained non-foamable resin composition is injected into the mold cavity from the injection gate portion 14 using the first injection molding machine, and then the obtained foamable resin composition is secondarily injected molded. A predetermined amount of the non-foamable resin composition is injected into the mold cavity from the injection gate portion 14 again using the first injection molding machine from the injection gate portion 14 using a machine. Therefore, the receiving portion at the end of the mold cavity is made of a non-foamed resin layer and is solid, the thickness between the inner and outer wall surfaces at the end of the receiving portion is 3.0 mm, and the length of the receiving portion is 22 mm. In the main body where the foamable resin is covered with the non-foamable resin in the mold cavity, the socket portion as shown in FIG. 1 having a foamed resin layer having a thickness between the inner and outer wall surfaces of 10 mm and a foaming magnification of 1.8 times. A two-layer structure pipe joint formed into a DV joint type having an inner diameter of 48.3 mm was manufactured.

The meanings of the abbreviations in Table 1 are shown below.
A: Content of monomeric unit based on acrylonitrile,
B: Content of diene-based rubber component,
S: Content of monomeric unit based on styrene,
MMA: Content of monomeric units based on methyl methacrylate,
A + MMA: Total content of monomeric units based on acrylonitrile and monomeric units based on methyl methacrylate

[Example 2]
Table 1 shows the content of each monomer unit obtained by measuring acrylonitrile monomer, styrene monomer, polybutadiene, methyl methacrylate monomer, and butyl acrylate by PGC / MS. A non-foamable resin composition was obtained in the same manner as in Example 1 except that the mixture was kneaded at such a ratio.
This non-foaming resin composition was pelletized and dried at 60 ° C. for 4 hours using a known hot air dryer. A dry pellet-shaped non-foamable resin composition mixed with ADCA (manufactured by Otsuka Chemical Co., Ltd., trade name "AZ-HM", azodicarbonamide) as a foaming agent was used as a foamable resin composition.
The obtained foamable resin composition is injected into a mold cavity filled with gas and pressurized at a molding temperature of 240 ° C., and then the gas in the mold cavity is removed and the pressure is reduced to foam the resin. The mouth is made of a non-foamed resin layer and is solid. A pipe joint in which a skin layer (non-foamed resin layer) is formed on the surface of a DV joint type with an inner diameter of 48.3 mm as shown in FIG. 1 having a foamed resin layer having a foaming resin layer of 10 mm and a foaming magnification of 1.8 times. Manufactured.

[Examples 3, 5 to 7, Comparative Examples 1 and 2]
Table 1 shows the content of each monomer unit obtained by measuring acrylonitrile monomer, styrene monomer, polybutadiene, methyl methacrylate monomer, and butyl acrylate by PGC / MS. A pipe joint having a skin layer (non-foamed resin layer) formed on the surface was produced in the same manner as in Example 2 except that the mixture was kneaded at such a ratio.

[Example 4]
Table 1 shows the content of each monomer unit obtained by measuring acrylonitrile monomer, styrene monomer, polybutadiene, methyl methacrylate monomer, and butyl acrylate by PGC / MS. A pipe joint having a two-layer structure was manufactured in the same manner as in Example 1 except that the mixture was kneaded in such a ratio.

[Measurement of MFR]
The MFR of the pipe fitting manufactured in each example was measured according to JIS K 7210: 1999 at a test temperature of 220 ° C. and a test load of 9.8 N. The results are shown in Table 1.

[Evaluation of chemical resistance]
The non-foamable resin composition used in the above Examples and Comparative Examples was injection-molded into a dumbbell shape having a length of 200 mm to obtain a test piece. The obtained test piece was fixed in a bending jig prepared to apply a stretching stress of 3 MPa in a room at 23 ° C., and 2 mL of polyethylene glycol (Nacalai Tesque # 200, average molecular weight 190 to 210) was immersed in 10 mm. A cotton having a size of × 20 mm was placed on the center of the test piece. Three test pieces were prepared for each example, and after leaving any one of the three test pieces for 36 hours, the cotton was removed and visually confirmed. The other two of the three test pieces were left for 72 hours, then the cotton was removed and visually confirmed to evaluate the chemical resistance. The chemical resistance was evaluated by checking the presence or absence of cracks in the test piece according to the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
◯: No breakage or cracks occurred even after 72 hours had passed.
Δ: Breakage and cracks occurred when the placement time was 1 hour or more and less than 72 hours.
X: Breakage and cracks occurred when the placement time was less than 1 hour.

[Evaluation of formability]
Based on the above Examples and Comparative Examples, 10 pipe joints are manufactured in each example, and molding defects (mainly short circuits due to the resin not being filled to the ends in the mold) occur in the sockets of the pipe joints. I visually confirmed that it was not done. The formability was evaluated according to the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
◯: No molding defects in all 10 pieces.
X: 1 or more molding defects.

As shown in Table 1, the pipe joints of each example had a sufficiently large MFR, good moldability, and excellent chemical resistance.
On the other hand, in Comparative Examples 1 and 2, either the moldability or the chemical resistance was insufficient.

1 Pipe fitting 10 Main body 20a, 20b, 20c Receptacle 30 Foamed resin layer 50 Non-foamed resin layer

Claims (8)

A pipe joint having a plurality of receiving portions into which a pipe member is inserted and having a flow path in which the plurality of receiving portions are communicated with each other.
At least, the portion in contact with the flow path is made of the resin composition (I).
The resin composition (I) contains a vinyl cyanide-based monomer unit, a diene-based monomer unit, an aromatic vinyl-based monomer unit, and a methacrylic-based monomer unit.
The content of the methacrylic monomer unit determined by pyrolysis gas chromatography-mass spectrometry (PGC / MS) is 30% by mass or less with respect to the entire resin component of the resin composition (I).
The total content of the vinyl cyanide-based monomer unit and the methacrylic-based monomer unit determined by the pyrolysis gas chromatography mass spectrometry (PGC / MS) is applied to the entire resin component of the resin composition (I). On the other hand, a pipe joint having 35 to 80% by mass. The content of the aromatic vinyl-based monomer unit determined by pyrolysis gas chromatography-mass spectrometry (PGC / MS) is 30% by mass or less with respect to the entire resin component of the resin composition (I). The pipe fitting according to claim 1. The pipe fitting according to claim 1 or 2, wherein the resin composition (I) contains acrylic rubber. Any one of claims 1 to 3, wherein the melt mass flow rate measured at a test temperature of 220 ° C. and a test load of 9.8 N is 5 g / 10 minutes or more according to JIS K 7210: 1999 of the resin composition (I). The pipe fitting described in item 1. The surface layer composed of the resin composition (I) and the foamed resin layer covered with the surface layer are provided, and the surface layer has a foaming ratio of 1.0 times or more and less than 1.1 times, and the foaming is performed. The pipe joint according to any one of claims 1 to 4, wherein the resin layer has a foaming ratio of 1.1 times or more. A piping structure comprising the pipe fitting according to any one of claims 1 to 5 and a pipe member inserted and connected to the receiving portion of the pipe joint. The method for producing a pipe joint according to any one of claims 1 to 5, wherein a foaming agent is mixed with the powder or pellet of the resin composition (I) to obtain an effervescent resin composition. A method for manufacturing a pipe joint, in which the foaming agent resin composition is injection-molded. The method for manufacturing a pipe joint according to claim 7, wherein the powder or pellet of the resin composition (I) is dried and then mixed with the foaming agent.

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