JP2018172600A - Foam pipe joint and method for producing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam pipe joint that is excellent in chemical resistance and impact resistance.SOLUTION: Provided is a foam pipe joint 1 formed by foaming and shaping a foamable resin composition containing a vinyl chloride resin and a foaming agent, and is characterized in: having a main body part 10 having a flow path inside and a socket part 12 formed integrally with the opening part 11 of the main body part 10, and in which (the thickness at the center of the socket part)/(the thickness at the center of the main body part) is 0.3 to 0.7, the expansion ratio at the center of the main body part is 1.2 to 2.5 folds, and the expansion ratio at the opening end part of the socket part 12 is 1.2 to 1.5 folds.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a foamed pipe joint and a method for manufacturing the same.

Conventionally, it is common to prevent condensation around the pipe by covering the pipe made of a steel pipe or a synthetic resin pipe with a heat insulating material such as glass wool.
However, the above-described conventional method requires a work for winding or covering the heat insulating material separately from the work of the piping, so that the work efficiency is low and the work may not be performed in a narrow work space.
Therefore, resin-made piping and pipe joints having a foam layer serving 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 pipe construction.
In general pipe joints, a receiving portion having an inner diameter larger than the opening of the main body is integrally provided at the opening of the main body serving as a flow path. A tube member is inserted.

  Patent Document 1 proposes a foamed pipe joint including a heat insulating layer made of foamed resin inside a main body. Patent Document 1 lists polyvinyl chloride, ABS resin, polyethylene, polypropylene, and the like as resins that can be used in the manufacture of pipe joints. In the current product, ABS resin having excellent impact resistance and heat resistance is used. ing.

Japanese Patent No. 3699579

In recent years, the use of foamed pipe joints has expanded, for example, there is a need for pipe joints having excellent chemical resistance.
Vinyl chloride resin is excellent in chemical resistance, but is inferior in impact resistance compared to the current ABS resin.
An object of this invention is to provide the foamed pipe joint excellent in chemical resistance and impact resistance, and its manufacturing method.

The present invention has the following aspects.
[1] A foamed pipe joint obtained by foaming and molding a foamable resin composition containing a vinyl chloride resin and a foaming agent, and a main body having a flow path therein and an opening of the main body The ratio of (thickness of the center of the mouthpiece) / (thickness of the center of the main body) is 0.3 to 0.7, and the expansion ratio at the center of the main body is A foamed pipe joint characterized by being 1.2 to 2.5 times and having a foaming ratio of 1.2 to 1.5 times at the open end of the receiving part.
[2] The method for producing a foamed pipe joint according to [1], wherein a foamable resin composition containing a vinyl chloride resin and a foaming agent is injection-molded.

  According to the present invention, a foamed pipe joint having excellent chemical resistance and impact resistance can be obtained.

It is a side view which shows the foaming pipe joint which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the foamed pipe joint shown in FIG. It is the sectional view on the AA line shown in FIG.

Hereinafter, a foamed pipe joint according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the foamed pipe joint 1 of this embodiment is a cheese type (tee type) pipe joint used for connection of a drain pipe, for example.
The foamed pipe joint 1 has a first pipe axis O1 and a second pipe axis O2. The two tube axes O1 and O2 are linear and orthogonal to each other.
The foamed pipe joint 1 includes a tubular main body portion 10 having a flow path (for example, a drain flow path) therein, and a receiving portion 12 formed integrally with each of the three openings 11 of the main body portion 10. The foamed pipe joint 1 is composed of a foamed resin layer in which a main body 10 and a receiving port 12 are integrally formed.
A tube member (for example, a drain pipe) having substantially the same inner diameter as the inner diameter of the opening portion 11 of the main body portion 10 is inserted into the receiving portion 12. The inner diameter D <b> 2 of the opening of the receiving portion 12 is larger than the inner diameter D <b> 1 of the opening 11 of the main body 10.

Hereinafter, two of the three openings 11 of the main body 10 have a circular shape coaxial with the first tube axis O1. The opening on one end side of the first tube axis O1 may be referred to as a first main body opening 11a, and the opening on the other end may be referred to as a second main body opening 11b. The remaining one has a circular shape coaxial with the second tube axis O2, and may be referred to as a third main body opening 11c.
Of the three receiving ports 12, two are tubular and coaxial with the first tube axis O1. The receiving portion on one end side of the first tube axis O1 may be referred to as a first receiving portion 12A, and the receiving portion on the other end side may be referred to as a second receiving portion 12B. The remaining one has a tubular shape coaxial with the second tube axis O2, and may be referred to as a third receiving portion 12C.
On the surface of the main body 10, an injection gate portion 14 is provided at a position where the distance from each opening 12 b of the first to third receiving portions 12 </ b> A to 12 </ b> C is farthest from that at the time of molding. It has been.

  As shown in FIG. 2, the inner surface of the receiving portion 12 has a tapered portion 12 a that gradually decreases inward from the opening portion 12 b and an end portion of the tapered portion 12 a on the main body portion 10 side from the end portion of the main body portion 10. Until the opening 11 is reached, the stepped portion 13 is further gradually reduced in diameter. The step portion 13 serves as a stopper against which the distal end surface of the pipe member inserted into the receiving portion 12 abuts.

The foamed pipe joint 1 is formed by foaming and molding a foamable resin composition containing a vinyl chloride resin and a foaming agent. The method for producing a foamed pipe joint of the present invention is a method for injection molding a foamable resin composition.
Specifically, the foamable resin composition is supplied to an injection molding machine, heated to melt the vinyl chloride resin, injected into a mold, and cooled to be molded into a desired shape. The foaming agent in the foamable resin composition is decomposed by heating to generate gas, and closed cells are formed in the melted vinyl chloride resin. The foamed pipe joint obtained in this way consists entirely of a foamed resin layer.
The injection gate portion 14 that is a position to be injected at the time of molding is not particularly limited as long as it is a position where the entire mold can be filled with the foamable resin composition. In the present embodiment, the injection gate portion 14 is provided on the surface of the main body portion 10 at a position where the distances from the opening portions 12b of the first to third receiving port portions 12A to 12C are farthest.
The temperature of the mold is lower than the temperature of the expandable resin composition immediately before injection, and the temperature of the injected expandable resin composition decreases while flowing in the mold. For example, the temperature (molding temperature) of the foamable resin composition immediately before being injected is preferably 150 to 190 ° C, and more preferably 160 to 180 ° C. Moreover, 20-100 degreeC is preferable and, as for the temperature of the metal mold | die just before a foamable resin composition is inject | emitted, 30-80 degreeC is more preferable.
The foamable resin composition will be described later.

In the foamed pipe joint 1, the ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) is 0.3 to 0.7.
In the present invention, it is a point on the longest tube axis (first tube axis O1 in the present embodiment), which is an opening on the one end side of the tube axis (first main body opening 11a) and the other end side. A cross section obtained by cutting the main body portion 10 along a plane perpendicular to the tube axis passing through the point P1 that is equidistant from the opening portion (second main body opening portion 11b) is a cross section at the center of the main body portion. In the present embodiment, of the cross section shown in FIG. 3, the portion indicated by the symbol R is a cross section at the center of the main body.
The thickness T1 of the main body 10 (excluding the injection gate) in the cross section at the center of the main body is defined as the thickness of the main body. In the cross section at the center of the main body, when the thickness T1 of the main body 10 is not uniform, the thickness at the thickest portion is the thickness at the center of the main body.
In the present invention, a point on the tube axis of the receiving port 12, which passes through a point P 2 that is equidistant from the opening 12 b of the receiving port 12 and the opening 11 of the main body 10, is perpendicular to the tube axis. The cross section obtained by cutting the receiving part 12 on the surface is taken as the cross section at the center of the receiving part. The thickness T2 of the receiving portion 12 in the cross section at the center of the receiving portion is defined as the thickness at the center of the receiving portion. When the thickness T2 of the receiving port 12 is not uniform in the cross-section at the center of the receiving port, the thickness at the thickest portion is set as the thickness of the receiving port.
The ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) may be within the above range in all of the plurality of receiving ports 12 constituting the foamed pipe joint 1.

In the present invention, the foaming ratio of the main body can be increased by increasing the ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) above the lower limit of the above range. As a result, the entire foamed pipe joint 1 is reduced in weight and the impact resistance is improved.
The reason why the expansion ratio of the main body is high is considered as follows. When the foamed pipe joint 1 is manufactured by injection molding, the foamable resin composition injected from the injection gate portion 14 flows in the mold and generates gas and foams while filling the space in the mold. . Regardless of the position of the injection gate part 14, a part of the foamable resin composition flows into the space corresponding to the receiving part 12 through the space corresponding to the main body part 10. At this time, since the thickness of the tube wall of the receiving portion 12 is smaller than that of the main body portion 10, the flow path of the foamable resin composition becomes narrow, and the foamable resin composition in the space corresponding to the main body portion 10. When pressure is applied to the main body, and the pressure is large, the expansion ratio of the main body portion is reduced.
In the present invention, the closer the (thickness at the center of the receiving port) / (thickness at the center of the main body) is to 1, the more the change in the size of the flow path of the foamable resin composition from the main body 10 to the receiving port 12 occurs. Since it becomes small, the pressure concerning the foamable resin composition in the space corresponding to the main-body part 10 is relieved, and it is thought that a foaming ratio becomes high.
On the other hand, if the ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) exceeds the upper limit of the above range, the foamable resin composition extends to every corner of the space corresponding to the receiving port 12. Insufficient pressure to fill the inlet portion 12 tends to cause molding failure of the receiving portion 12.
The ratio of (thickness at the center of the opening) / (thickness at the center of the main body) is preferably 0.3 to 0.7, and more preferably 0.4 to 0.6.
For example, the thickness T1 at the center of the main body is preferably 6 to 12 mm, and more preferably 8 to 10 mm.
The thickness T2 at the center of the opening is preferably 2 to 8 mm, for example, and more preferably 4 to 5 mm.

The foaming pipe joint 1 has a foaming ratio of 1.2 to 1.5 times at the opening end of the receiving part.
The foaming magnification at the opening end of the receiving portion is determined by cutting an annular sample having a thickness of 1 to 2 mm including the end face of the opening 12b of the receiving portion, measuring its specific gravity (x), and not foaming. This is a value obtained by dividing the specific gravity of the resin by the specific gravity (x) of the sample.
Specifically, “foaming ratio = specific gravity of resin when not foamed / x” is set as the value of the foaming ratio at the opening end. The specific gravity of the resin when not foamed can be measured from the melted sample.
The specific gravity is measured according to JIS 7122 at 23 ° C. ± 2 ° C. using a water displacement specific gravity measuring instrument.
The closer the foaming magnification at the opening end of the receiving portion is to 1.0 times, the higher the strength of the opening and the better the impact resistance.
When the expansion ratio at the opening end of the receiving portion is not less than the lower limit of the above range, the heat insulating performance is excellent, and when it is not more than the upper limit, the impact resistance is excellent.
In the plurality of receiving portions, when the expansion ratios at the opening end portions are different from each other, the largest value may be within the above range.

In this embodiment, since the injection gate part 14 is provided in the position where the distance from each opening part 12b of the 1st-3rd receiving part 12A-12C is the furthest, the injected foamed resin composition is The temperature of the foamable resin composition tends to be lower when it flows through the space in the mold and reaches the opening 12b. The lower the temperature of the foamable resin composition filled in the opening end, the lower the expansion ratio of the opening end.
In the present embodiment, the inner surface of the receiving portion 12 has a tapered portion 12a, and the thickness of the tube wall of the receiving portion 12 decreases toward the opening portion 12b. That is, the space corresponding to the receiving port 12 in the mold is narrowed toward the opening 12b. The narrower the space corresponding to the opening end, the lower the expansion ratio of the opening end.
The angle θ (hereinafter also referred to as taper angle θ) formed by the tapered portion 12a of the receiving portion 12 and the outer surface of the receiving portion 12 is preferably 0.05 to 1.5 °, for example, 0.07 to 1. 2 ° is more preferable, and 0.09 to 1.18 ° is most preferable.
If the thickness T3 of the receiving portion 12 in the opening 12b is too thin, the opening 12b of the receiving portion 12 is hardly chipped when subjected to an impact. The thickness T3 is preferably 2 to 8 mm, for example, and more preferably 4 to 5 mm.

The expansion ratio of the foamed pipe joint 1 at the center of the main body is preferably 1.2 to 2.5 times, more preferably 1.3 to 2.5 times, and most preferably 1.5 to 2.2 times. .
The foaming magnification at the center of the main body is obtained by cutting out a sample having a thickness of 1 to 2 mm including the cross section at the center of the main body, measuring the specific gravity value (y), and determining the specific gravity of the resin when not foamed by the specific gravity of the sample ( The value obtained by dividing by y).
Specifically, “foaming ratio = specific gravity of resin when not foamed / y” is set as the value of the foaming ratio at the center of the main body.
The specific gravity is measured according to JIS 7122 at 23 ° C. ± 2 ° C. using a water displacement specific gravity measuring instrument.
When the expansion ratio at the center of the main body is not less than the lower limit of the above range, the heat insulating performance is excellent, and when it is not more than the upper limit, the impact resistance is excellent.
The expansion ratio at the center of the main body can be adjusted by, for example, molding temperature, product thickness, and composition.

<Foaming resin composition>
The foamable resin composition contains a vinyl chloride resin and a foaming agent.
As the vinyl chloride resin, a known hard vinyl chloride resin can be used as a material for the pipe joint. The hard vinyl chloride resin is a vinyl chloride resin substantially free of a plasticizer.
The vinyl chloride resin may be a homopolymer of a vinyl chloride monomer or a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer. Good.
Examples of other monomers copolymerizable with the vinyl chloride monomer include, for example, ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl acetate, maleic anhydride, and acrylonitrile. And the like. These may be used alone or in combination of two or more.
A vinyl chloride resin may be used independently and 2 or more types may be used together.
The average degree of polymerization of the vinyl chloride resin is preferably 450 to 800, more preferably 600 to 700.

As the foaming agent, either a volatile foaming agent or a decomposable foaming agent may be used.
Examples of the volatile foaming agent include aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers, and ketones. Among 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, difluoroethane, and the like. Furthermore, examples of the ether include dimethyl ether and diethyl ether, and examples of the ketone include acetone and methyl ethyl ketone.
Examples of the decomposable foaming agent include sodium bicarbonate (sodium bicarbonate), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compound, sodium borohydride and other inorganic foaming agents, azodicarbonamide, barium azodicarboxylate And 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 decomposable foaming agent is preferable, and sodium bicarbonate and azodicarbonamide are more preferable.
These may be used alone or in combination of two or more.
0.1-8 mass parts is preferable with respect to 100 mass parts of vinyl chloride resin, the usage-amount of a foaming agent has more preferable 2-5 mass parts, and its 1-3 mass parts are the most preferable.

The foamable resin composition may contain other components (optional components) other than the vinyl chloride resin and the foaming agent. Examples of optional components include known additives such as stabilizers, lubricants, processing aids, and pigments.
As the stabilizer, a known compound can be used as a stabilizer for the vinyl chloride resin. For example, lead-based stabilizers, CaZn-based stabilizers, tin-based stabilizers and the like can be mentioned, but it is preferable that the foamable resin composition does not contain lead-based stabilizers.
When the lead-based stabilizer is contained in the foamable resin composition, the decomposition of the organic foaming agent such as azodicarbonamide is activated, and the foaming start temperature is lowered. As a result, a foaming residue is generated, and a product defect called burn (discolored foreign matter) tends to occur, which is not preferable.

The stabilizer in the foamable resin composition is preferably a tin-based stabilizer. By using a tin-based stabilizer, it becomes easy to increase the thermal stability of the vinyl chloride resin, and the occurrence of burns can be suppressed. As the tin stabilizer, an organic acid salt of dialkyl tin can be used. Examples of the alkyl group include methyl, butyl, and octyl. Examples of organic acids include mercapto compounds such as esters of thioglycolic acid and esters of mercaptoethanol; malate compounds such as maleic acid esters and organic tin salts of maleic acid half esters; laurate compounds such as salts of lauric acid, etc. Is mentioned. From the viewpoint of ensuring the transparency of the non-foamed layer, a mercapto compound is preferred as the tin stabilizer. For example, dibutyltin mercaptan, dioctyltin mercaptan, etc. are mentioned.
These tin stabilizers may be used alone or in combination of two or more. From the viewpoint of further improving the thermal stability of the vinyl chloride resin and improving the workability, it is preferable to use two or more tin stabilizers in combination.
The tin stabilizer may be used alone or in combination of two or more.

The content of the tin-based stabilizer is preferably 95% by mass or more, particularly preferably 100% by mass with respect to the total mass of the stabilizer.
The content of the tin-based stabilizer is preferably 0.1 parts by mass or more and 10 parts by mass or less, 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 vinyl chloride resin. More preferred is 5 parts by mass or more. When the content of the tin stabilizer is equal to or more than the lower limit, the thermal stability of the vinyl chloride resin can be easily increased. It is easy to improve the heat resistance of a foamable resin composition and workability as it is below the said upper limit.

  The content of the optional component is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 10 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin.

The foamed pipe joint of the present invention is obtained by foaming and molding a foamable resin composition containing a vinyl chloride resin and a foaming agent, and is excellent in chemical resistance and heat insulation. Moreover, it is excellent in impact resistance, although the whole is a molded article made of a foamed layer of vinyl chloride resin.
The shape of the pipe joint is not limited to the cheese type (tea type) of the present embodiment, and various shapes such as an elbow, a reducer, a valve socket, and a nipple can be applied.

Hereinafter, the present invention will be described in more detail using 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.

[Raw materials]
Vinyl chloride resin: Degree of polymerization 640, manufactured by Tokuyama Sekisui Industry Co., Ltd., trade name “TS-640M”.
Foaming agent: Azodicarbonamide, manufactured by Eiwa Kasei Co., Ltd., trade name “AC3”.
Stabilizer: Methyl tin, manufactured by Katsuta Chemical Co., Ltd., trade name “KM-19D-2”.

[Impact resistance test]
A drop test was carried out by dropping from a height of 1 m onto a floor (material: concrete) at an atmospheric temperature of 0 ° C. and judged according to the following criteria. The drop test is performed on all of the plurality of receiving portions of one foamed pipe joint. Therefore, the cheese type pipe joint was subjected to a drop test three times so that the three receiving portions collide with the floor.
X: Cracks occurred at one or more receiving portions.
○: No cracks occurred in all the receiving parts.

(Examples 1-6)
Examples 2 to 4 are examples, and examples 1, 5, and 6 are comparative examples.
A foamable pipe joint having a shape shown in FIGS. 1 to 3 was produced by injection molding a foamable resin composition in which 100 parts by mass of a vinyl chloride resin, 1 part by mass of a foaming agent, and 2 parts by mass of a stabilizer were mixed. The molding temperature was 170 ° C., the mold temperature was 40 ° C., and the molding time from the start of injection to demolding was 120 seconds.
The dimensions of the mold were changed so that the dimensions of the foamed pipe joint were as shown in Table 1.
Example 5 was the same as Example 3 except that the position of the injection gate in Example 3 was changed to the vicinity of the opening of the receiving port.
About the obtained foamed pipe joint, each item shown in Table 1 was measured or evaluated. The specific gravity of the resin when not foamed was 1.4. The results are shown in Table 1.
In Example 6, since the molding of the opening 12b was poor due to insufficient filling of the foamable resin composition, the measurement of the expansion ratio and the impact resistance test at the opening end were not performed.

As shown in the results of Table 1, the ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) is 0.3 to 0.7, and the expansion ratio at the center of the main body is 1. The foamed pipe joints of Examples 2 to 4 that are 2 to 2.5 times and the foaming magnification at the opening end of the receiving portion is 1.2 to 1.5 times are excellent in impact resistance.
On the other hand, although the expansion ratio at the opening end of the receiving port is 1.0, the ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) is small. The expansion ratio at the center of the part is low and the impact resistance is poor.
In Example 5, since the position of the injection gate portion 14 is changed, the expansion ratio at the opening end portion of the receiving portion is increased, and the impact resistance is inferior.
In Example 6, since the thickness (T2) at the center of the receiving part is too large, it is considered that insufficient filling of the foamable resin composition occurred in the receiving part.

DESCRIPTION OF SYMBOLS 1 Foam pipe joint 10 Main-body part 11 Opening part 11a 1st main-body opening part 11b 2nd main-body opening part 11c 3rd main-body opening part 12 Receiving part 12A 1st receiving part 12B 2nd receiving part 12C Third receiving portion 12a Taper portion 12b Opening portion 13 Step portion 14 Injection gate portion O1 First tube axis O2 Second tube shaft

Claims (2)

A foam pipe joint formed by foaming and molding a foamable resin composition containing a vinyl chloride resin and a foaming agent,
A main body having a flow path inside, and a receiving portion formed integrally with the opening of the main body,
The ratio of (thickness at the center of the receiving port) / (thickness at the center of the main body) is 0.3 to 0.7,
A foamed pipe joint having a foaming ratio of 1.2 to 2.5 times at the center of the main body and a foaming ratio of 1.2 to 1.5 times at the opening end of the receiving part.   The method for producing a foamed pipe joint according to claim 1, wherein a foamable resin composition containing a vinyl chloride resin and a foaming agent is injection-molded.

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