JP2010230033A - Pipe joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe joint molded from synthetic resin in its entirety and having high rigidity causing no crack even when fastened to a metal screw part of a connection counterpart. <P>SOLUTION: The pipe joint 1 is molded by steps of: charging a cylindrical body 2 of thermoplastic resin having a screw part on a peripheral surface and formed by weldless molding in a joint mold; filling thermoplastic resin different from the molding resin of the cylindrical body 2 into the joint mold; and covering a part or the whole of the cylindrical body with the molten resin and solidifying the molten resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a synthetic resin pipe joint applied to a valve socket, a faucet joint, and the like.

2. Description of the Related Art Conventionally, a tubular insert made of gunmetal (metal) having a threaded portion 101a formed on the peripheral surface thereof as shown in FIG. 2 as a valve socket or a faucet joint made of a synthetic resin used to connect water supply pipes. A pipe joint 100 formed by embedding 101 in the connection opening 100a by injection molding is often used.
The valve socket is used for connection with a metal valve or a water meter, the water tap joint is used for connection with a water tap, the connection portion is reinforced with a metal tubular insert 101, and the screw portion. This is because the connection is easy if 101a is made of metal (see, for example, Patent Documents 1 and 2).

Japanese Utility Model Publication No. 61-27703 JP-A-8-219360

The pipe joint 100 in which the tubular insert 1 made of gunmetal is embedded can reinforce the connection part, but the weight of the product is heavy, the manufacturing cost is high, and the tubular insert 101 is rusted during product storage. It is time consuming and is not suitable for use as an ultrapure water fitting because the amount of metal elution is relatively large. Further, it is difficult to separate the tubular insert 101 when disposing of the product, resulting in poor recyclability. There is.
On the other hand, if the entire pipe joint is molded from synthetic resin without using the tubular insert 101 made of gunmetal, the manufacturing cost can be reduced and separation and disposal are not required. However, a relatively large weld (joint) appears in the pipe joint. If it is extended, the rigidity is remarkably lowered, and there is a problem that the pipe joint is easily cracked when it is fastened to the metal screw part of the connection partner.

  SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a pipe joint that is entirely made of synthetic resin and has high rigidity that does not cause cracking even if it is fastened to a metal screw part of a connection partner. The task is to do.

  In order to solve the above-described problems, the pipe joint of the present invention is a cylinder made of a thermoplastic resin formed by weldless molding having a threaded portion on the peripheral surface, and loaded into a joint mold. It is characterized in that it is formed by injecting a different thermoplastic resin into the joint mold and covering and solidifying a part or the whole of the cylindrical body with a molten resin.

  The pipe joint of the present invention has a cylindrical body having a threaded portion formed on a peripheral surface formed by injecting a thermoplastic resin into a weldless mold, and has a thermoplasticity different from the molding resin of the cylindrical body. It is characterized in that it is formed by injecting resin into the joint mold and covering and solidifying a part or the whole of the cylindrical body with molten resin.

  Moreover, the pipe joint of the present invention is installed in the joint mold in a state where the cylindrical body having a threaded portion on the peripheral surface formed by injecting the thermoplastic resin into the weldless mold is left in the same core, A thermoplastic resin different from the molding resin of the cylinder is poured into the joint mold, and a part or the whole of the cylinder is covered with a molten resin and solidified.

The pipe joint having the above-described structure is formed by forming a cylindrical body having a threaded portion on the peripheral surface, and thereafter or simultaneously with this, the outer portion of the cylindrical body is formed by injection molding, and the cylindrical portion is formed when the outer portion of the cylindrical body is molded. The body needs to be held in its initial shape.
Therefore, in the pipe joint having the above-described configuration, it is preferable that the molding resin of the cylindrical body has a melting point or glass transition point higher than the melting point or glass transition point of the molding resin of the outer portion of the cylindrical body. More specifically, when the molding resin of the cylindrical body is crystalline, the melting point (Tm; Tm1) is higher than the melting point (Tm2) of the molding resin of the outer portion, or the glass transition point (Tg; Tg2). When the molding resin is amorphous, its glass transition point (Tg1) is higher than the melting point (Tm2) of the molding resin at the outer portion or the glass transition point (Tg2) (T1> Tm2, Tm1>). Tg2, Tg1> Tg2) is preferred.

In the pipe joint of the present invention, as shown in FIG. 1, a pipe body 2 made of a thermoplastic resin having a threaded portion on the peripheral surface is arranged at one connection port 11 of the pipe joint 1. The outer portion 3 of the cylindrical body 2 including the other connection port 12 of the pipe joint 1 is integrally formed with a thermoplastic resin different from the thermoplastic resin so as to be covered. The cylindrical body 2 is preferably formed by weldless molding in order to increase rigidity, and most preferably has a configuration without a weld line.
When the pipe joint 1 is a valve socket, as shown in FIG. 2A, a cylinder 2 having a threaded portion 21 made of a taper male screw formed on the outer peripheral surface is inserted into the connection port 11, and the cylinder 2 The inner peripheral surface and the inner end are covered with the outer portion 3 and are solidified integrally.
In addition, when the pipe joint 1 is a faucet joint, as shown in FIG. 5B, the cylindrical body 2 in which the thread portion 21 made of an internal thread is formed on the inner peripheral surface is inserted into the connection port 11, The entire outer peripheral surface of the cylinder 2 is covered with the outer portion 3 and solidified integrally.
Note that the pipe joint 1 of the present invention is not limited to the illustrated valve socket and water tap joint, and the shape of the tubular body 2 and the overall shape of the pipe joint 1 are also limited to those illustrated. Not.

  In the pipe joint having the above-described configuration, a thermoplastic resin having a tensile strength of 70 MPa or more is preferable as the thermoplastic resin forming the cylindrical body having the threaded portion on the peripheral surface. For example, it is preferable to use a polyphenylsulfone resin, a polyphthalamide resin, a polyphenylene sulfide resin, a mixture thereof, or a mixture with a filler such as glass fiber.

In the cylindrical molding resin, the polyphenylsulfone resin preferably has a density of 1.20 g / cm ³ or more and 1.60 g / cm ³ or less and a glass transition temperature of 200 ° C. or more.
As the polyphthalamide resin, density 1.20 g / cm ³ or more, with 1.80 g / cm ³ or less, a melting point of 300 ° C. or higher, preferably those 330 ° C. or less. In order to improve mechanical strength, it is preferable to add a glass fiber to a polyphthalamide resin at 30 wt% or more and 70 wt% or less, and it is more preferable that the addition range is 30 wt% or more and 50 wt% or less.
The polyphenylene sulfide resin, density 1.20 g / cm ³ or more, with 1.90 g / cm ³ or less, a melting point of 280 ° C. or higher, preferably from 350 ° C. or less. In order to improve mechanical strength, it is preferable to add a glass fiber to a polyphenylene sulfide resin at 30 wt% or more and 70 wt% or less, and it is more preferable that the addition range is 30 wt% or more and 40 wt% or less.

  In the pipe joint having the above-described configuration, the thermoplastic resin that covers a part or the whole of the cylinder and forms the outer part of the cylinder is made of a material that can be joined in the same manner as a synthetic resin pipe that is distributed in the market. It is preferable. For example, it is preferable to use a vinyl chloride resin, a polyethylene resin, a polybutene resin, or a mixture thereof.

In the molding resin of the outer portion of the cylindrical body, the vinyl chloride resin is preferably one having a glass transition temperature of 70 ° C. or higher, a Vicat softening temperature of 70 ° C. or higher, and an average degree of polymerization of 600 or higher and 1400 or lower.
As the polyethylene resin, a high density polyethylene resin (HDPE) having a density of 0.94 g / cm ³ or more and 0.97 g / cm ³ or less, a density of 0.92 g / cm ³ or more, 0.94 g / cm ³ The following medium density polyethylene resin (MDPE), low density polyethylene resin (LDPE) or linear low density polyethylene resin (LLDPE) having a density of less than 0.92 g / cm ³ , density of 0.94 g / cm ³ or more, 0 It is preferable to use a crosslinked polyethylene resin (XPE) or the like of 97 g / cm ³ or less.
Examples of the linear low density polyethylene resin (LLDPE) include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 4 to 12 carbon atoms. Examples of the α-olefin include propylene, 1-butene, 1-penter, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-1-butene, 4-methyl- Examples include 1-pentene, and 1-butene, 1-hexene, and 1-octene are preferable. The α-olefin to be copolymerized may be used alone or in combination of two or more.
The polyethylene resin preferably has a density of 0.90 g / cm ³ or more and 0.97 g / cm ³ or less. A more preferable density is in the range of 0.92 g / cm ³ or more and 0.96 g / cm ³ or less. If the density is 0.90 g / cm ³ or more, the decrease in rigidity and heat resistance of the pipe material is small and preferable in practical use.
The melt flow rate (MFR) of the polyethylene-based resin is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 2.16 kg) is 0.1 g / 10 min or more, 15 g / 10 min. Or less, more preferably 0.1 g / 10 min or more and 10 g / 10 min or less.

Specific examples of each thermoplastic resin include the following.
Specific examples are the “Radel R” series from Solvay as polyphenylsulfone resins, the “Amodel” series from Solvay as polyphthalamide resins, and the “DIC.PPS” series from DIC as polyphenylene sulfide resins. .
Specific examples of polyethylene resins include “Novatech HD, LD, LL” series, “Kernel” series, “Toughmer A, P” series made by Nippon Polyethylene, and “Suntech HD, LD” made by Asahi Kasei Chemicals. Series, Mitsui Chemicals '“HIZEX”, “ULTZEX”, “EVOLUE” series, Ube Industries' “UBE polyethylene”, “UMERIT” series, Nippon Unicar's “UNC polyethylene”, “Nackflex” series, Dow Chemical Examples include “engage” and “DOWLEX” series. Specific examples of the polybutene-based resin include “Idemitsu Polybutene” series manufactured by Idemitsu Kosan Co., Ltd., “Nisseki Polybutene” series manufactured by Nippon Oil Corporation, and “Buron” series manufactured by Mitsui Chemicals.

The pipe joint of the present invention can be formed by insert molding configured as follows, for example.
That is, first, in order to mold a cylinder alone, a thermoplastic resin such as polyphenylsulfone resin, polyphthalamide resin, polyphenylene sulfide resin, etc. is put into an injection molding machine, melted, The molten resin passes through the sprue and the runner, and a cylindrical body having a predetermined screw shape is formed. The temperature at this time is appropriately adjusted depending on the composition and additives. Generally, 280 ° C to 400 ° C is preferable. The mold temperature is preferably adjusted from 140 ° C to 200 ° C.
Next, the molded cylinder is placed on the core side of a joint mold, which is a mold for molding the entire pipe joint, in order to mold the outer portion of the cylinder with a different material thermoplastic resin. A cavity is formed around the cylindrical body by sliding the core of the arranged joint mold. Thereafter, after the thermoplastic resin in the outer portion is put into an injection molding machine and melted, the molten resin passes through the sprue and runner in the mold to form a pipe joint having a predetermined joint shape. The temperature at this time is appropriately adjusted depending on the composition and additives. In general, the temperature is preferably 160 ° C to 210 ° C.

Moreover, the pipe joint of this invention can be formed by the simultaneous injection molding comprised as follows, for example.
In other words, simultaneous injection molding is performed by first molding a thermoplastic resin for a cylinder in a molding machine having two injection molding machines for molding a cylinder and its outer part and one joint mold for molding a pipe joint. After that, the molded cylinder is moved in a mold of the molding machine and moved to be placed at a predetermined position in the joint mold, and the outer portion of the thermoplastic resin is melt-filled in the joint mold. Then, a pipe joint having a predetermined joint shape is formed.

As described above, it is most desirable that the cylinder has no weld line, and the cylinder is formed by weldless molding so that the weld line is as small as possible.
In this case, the mold for forming the cylindrical body has a structure in which a weld line cannot be formed or is difficult to perform, specifically, a gate structure such as a film gate, a fan gate, and a ring gate. A cylindrical body having a predetermined shape can be formed by attaching to an injection molding machine, charging and melting the thermoplastic resin for the cylinder into the injection molding machine, and passing the molten resin through the sprue and runner in the mold.
In addition, even a mold that normally has a weld line is formed by heat and cool molding, specifically by a molding process in which a portion where the weld can be made is heated through steam for a predetermined period and then rapidly cooled through cold water. It is possible to form a cylindrical body having a predetermined shape with no weld line or very small weld line.
The process of forming the cylindrical body in a well-dressed manner is not limited to the above, and can be performed by adjusting molding conditions such as increasing the temperature of the molten resin or increasing the mold temperature.
In addition, the method and processing process which shape | mold the pipe joint of this invention are not limited to the shaping | molding method or process mentioned above, You may be based on the other shaping | molding method and shaping | molding process.

An example of the pipe joint of this invention is shown, (A) is sectional drawing of the socket for valves, (B) is principal part sectional drawing of the joint for water taps. It is sectional drawing of an example of the conventional pipe joint.

The pipe joint of the present invention will be specifically described based on Examples and Comparative Examples.
In the following examples and comparative examples, the valve socket shown in FIG. 1 (A) and the faucet joint shown in FIG. 1 (B) were molded and evaluated for performance as pipe joints. It is. The sizes of the formed pipe joints are all 20 sizes (nominal diameter 20).
The present invention is not limited to these examples.

Example 1
A valve socket was formed as the pipe joint 1.
Solvay A-1145HS (polyphthalamide) is used as the thermoplastic resin of the cylindrical body 2, and a mold capable of being welded is attached to an injection molding machine under conditions of a resin temperature of 320 ° C. and a mold temperature of 145 ° C. The cylinder 2 was molded with an injection molding machine. Next, a vinyl chloride resin was used as the thermoplastic resin of the outer portion 3, the tubular body 2 was placed in the core portion of the joint mold, and the pipe joint 1 having the thermoplastic resin screw portion 21 was formed by insert molding. .
About the pipe joint 1 shape | molded in this way, the weight was measured and the rust prevention property and recyclability were evaluated. The results are shown in Table 1.

(Example 2)
A water faucet joint was formed as the pipe joint 1.
Solvay A-1145HS (polyphthalamide) is used as the thermoplastic resin of the cylindrical body 2, and a mold capable of being welded is attached to an injection molding machine under conditions of a resin temperature of 320 ° C. and a mold temperature of 145 ° C. The cylinder 2 was molded with an injection molding machine. Next, a vinyl chloride resin was used as the thermoplastic resin of the outer portion 3, the tubular body 2 was placed in the core portion of the joint mold, and the pipe joint 1 having the thermoplastic resin screw portion 21 was formed by insert molding. .
The pipe joint 1 thus molded was weighed and evaluated for rust prevention, low elution, recyclability, and fastness. The results are shown in Table 1, Table 2 and Table 3.

Example 3
A valve socket was formed as the pipe joint 1.
DIC Z-230 (polyphenylene sulfide) is used as the thermoplastic resin for the cylindrical body 2 and a mold capable of being welded is attached to an injection molding machine, and injection is performed under conditions of a resin temperature of 300 ° C. and a mold temperature of 125 ° C. The cylinder 2 was molded with a molding machine. Next, a vinyl chloride resin was used as the thermoplastic resin of the outer portion 3, the tubular body 2 was placed in the core portion of the joint mold, and the pipe joint 1 having the thermoplastic resin screw portion 21 was formed by insert molding. .
About the pipe joint 1 shape | molded in this way, the weight was measured and the rust prevention property and recyclability were evaluated. The results are shown in Table 1.

Example 4
A water faucet joint was formed as the pipe joint 1.
DIC Z-230 (polyphenylene sulfide) is used as the thermoplastic resin for the cylindrical body 2 and a mold capable of being welded is attached to an injection molding machine, and injection is performed at a resin temperature of 300 ° C. and a mold temperature of 125 ° C. The cylinder 2 was molded with a molding machine. Next, a vinyl chloride resin was used as the thermoplastic resin of the outer portion 3, the tubular body 2 was placed in the core portion of the joint mold, and the pipe joint 1 having the thermoplastic resin screw portion 21 was formed by insert molding. .
The pipe joint 1 thus molded was weighed and evaluated for rust prevention, low elution, recyclability, and fastness. The results are shown in Table 1, Table 2 and Table 3.

(Comparative Example 1)
Valve sockets were molded as pipe joints.
Simultaneous injection molding by an injection molding machine in which a barrel made of gunmetal having a threaded part consisting of a male pipe taper on the outer peripheral surface is placed in the core part of a resin mold and vinyl chloride resin is introduced as a molding resin for the outer part A pipe joint having a screw part made of gunmetal was formed.
The pipe joint thus formed was weighed and evaluated for rust prevention and recyclability. The results are shown in Table 1.

(Comparative Example 2)
A water tap joint was formed as a pipe joint.
Simultaneous injection molding by an injection molding machine in which a barrel made of gunmetal having a threaded part consisting of parallel female threads on the inner peripheral surface is placed in the core part of the resin mold and vinyl chloride resin is introduced as a molding resin for the outer part A pipe joint having a screw part made of gunmetal was formed.
The pipe joint thus formed was weighed and evaluated for rust prevention, low elution, recyclability, and fastness. The results are shown in Table 1, Table 2 and Table 3.

(Comparative Example 3)
A water tap joint was formed as a pipe joint.
DIC Z-230 (polyphenylene sulfide) is used as the resin for molding the entire pipe joint, and is a joint mold for molding the entire pipe joint. The threaded part is molded at a resin temperature of 300 ° C and a mold temperature of 125 ° C. A pipe joint in which a weld was exposed was formed.
The pipe joint formed in this way was evaluated for fastening performance. The results are shown in Table 3.

The evaluation contents of each evaluation item are as follows.
(1) Weight measurement The weight of the pipe joint of an Example and a comparative example was measured to the last digit. The unit of the measurement results shown in Table 1 is g.
(2) Rust prevention property The pipe joints of the examples and comparative examples were stored indoors at room temperature (23 ° C.) for 6 months after molding, and it was confirmed whether or not rust occurred. In the measurement results shown in Table 1, “O” was indicated for those that could be confirmed that rust was not generated, and “X” was indicated for those that were confirmed to be rusted.
(3) Low elution: For the pipe joints of Examples 2 and 4 and Comparative Example 2, Zn was immersed in ultrapure water for 9 days in a room temperature environment, and the quality of ultrapure water is considered to be affected. It was measured how much each metal component of Pb, Fe, Cu, and Sn was eluted. In Table 2 showing the measurement results, the amount of each metal component eluted from Comparative Example 2, which is the current product, is 1, and in Examples 2 and 4, the ratio of the amount of eluted metal component to Comparative Example 2 is shown.
(4) Recyclability Regarding the pipe joints of the example and the comparative example, it was confirmed whether or not the cylinder and its outer part could be recycled in the factory. The measurement results shown in Table 1 indicate that if all the parts that make up the pipe joint can be crushed and recycled in the factory, it is possible. X was shown respectively.
(5) Fastening For the pipe joints of Examples 2 and 4 and Comparative Examples 2 and 3, the metal pipe taper male screw was fastened using a torque wrench to the connection port in which the tubular body of the pipe joint was loaded. It was confirmed whether or not the screw portion could be fastened to a state where it could not be fastened. In the measurement results shown in Table 3, “O” was indicated when the fastening was possible until it was impossible to fasten, and “X” was indicated when a crack occurred during the fastening.

  As is apparent from the evaluation results, the pipe joint of the present invention has substantially the same mechanical strength as that of a pipe joint in which a metal tubular insert, which is a current product, is embedded, and is fastened to a metal screw part of a connection partner. However, it is possible to securely and firmly connect the connected tube bodies without causing cracks. In addition, because it is molded entirely from synthetic resin, it is lightweight, easy to handle, and can be manufactured at low cost. Since metal parts are not used, the amount of metal elution is extremely small. Has a practical effect that all parts can be crushed and recycled.

1 pipe joint, 11, 12 connection port, 2 cylinder, 21 threaded part

Claims (4)

  A cylindrical body made of thermoplastic resin formed by weldless molding having a threaded portion on the peripheral surface is loaded into a joint mold, and a thermoplastic resin different from the molding resin of the cylindrical body is injected into the joint mold, A pipe joint formed by covering and solidifying a part or the whole of a cylindrical body with a molten resin.   A cylindrical body having a thread portion on a peripheral surface formed by injecting a thermoplastic resin into a weldless mold is loaded into the joint mold, and a thermoplastic resin different from the molding resin of the cylindrical body is loaded into the joint mold. A pipe joint formed by injecting, covering or solidifying a part or the whole of a cylindrical body with a molten resin.   A cylinder with a thread on the circumference formed by injecting thermoplastic resin into the weldless mold is placed in the joint mold with the same core remaining, and the thermoplasticity is different from the molding resin of the cylinder A pipe joint formed by injecting resin into the joint mold, and covering and solidifying a part or the whole of the cylindrical body with molten resin. The pipe joint according to any one of claims 1 to 3, wherein a thermoplastic resin having a melting point and a glass transition point higher than that of the thermoplastic resin forming the outer portion of the cylindrical body is used as the molding resin for the cylindrical body. .

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