JP2001041362A - Triple layer pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a triple layer pipe capable of making effective use of a derived product or wasted material of a product made of vinyl chloride resin or wasted material of stop resin, which are used to be wasted or burnt out. SOLUTION: This triple layer pipe is so constituted as to be formed out of an intermediate layer 12 made out of hard vinyl chloride resin including regerated material obtained from a derived product and/or wasted material, which are made of vinyl chloride resin, an outer layer 11 made out of hard vinyl chloride resin containing no regenerated material, provided in such a way as to cover the outer circumferential surface of the intermediate layer 12, and of an inner layer 13 made out of hard vinyl chloride resin containing no regenerated material, provided in such a way as to cover the inner circumferential surface of the intermediate layer 12. Three layers can be sufficiently formed up by using thermal stabilizing agent contained in the regenerated material through the use of the regenerated material obtained out of wasted stop resin containing a lot of thermal stabilizing agent contained in the intermediate layer 12, and thus, the derived product or the wasted material of the product made out of vinyl chloride resin can thereby be effectively utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-layer pipe having an inner layer and an outer layer and an intermediate layer sandwiched between the inner layer and the outer layer.

[0002]

2. Description of the Related Art Vinyl chloride resin is used as a material for various molded articles.
Derived products such as defective moldings and offcuts will inevitably occur. In addition, at the PVC pipe manufacturing plant, at the end of the extrusion molding of the product, a special composition of vinyl chloride called a stop resin containing a large amount of a heat stabilizer compared to the resin raw material used for ordinary PVC pipes When the resin and the resin in the mold are exchanged and molding is started again, the stop resin is extruded with vinyl chloride resin for a new product.

That is, if the resin material for the product is left in the mold as it is at the end of the extrusion molding, the resin is thermally decomposed in the mold to generate hydrogen chloride, which may cause damage to people or equipment. There is. Therefore, at the end of the extrusion molding, the mold is filled with the stop resin, and the molding resin is discharged from the mold and replaced with the stop resin. Then, the stop resin extruded from the mold at the time of molding the product again becomes waste material.

Conventionally, such derivatives and used waste materials have been conventionally incinerated or landfilled. However, incineration of these derivatives and waste materials may cause pollution such as global warming due to the generation of dioxin and an increase in the amount of carbon dioxide in the atmosphere, and also waste resources. Thus, in recent years, various attempts have been made to pulverize these derivatives and waste materials and use them as recycled materials. However, they have not been sufficiently effective yet, and many of them are used for incineration.

For example, when a pulverized product obtained from these derivatives is used as a regenerating raw material to produce a PVC regenerating tube, if the regenerating materials having different colors are mixed, a color different from the conventional PVC tube is obtained. Of course it will be,
The same standard is used even if the gray PVC pipe-only recycled material specified in JIS K 6741 (hard PVC pipe) or JIS K 6742 (hard PVC pipe for water supply) occupies 70% or more of the use. Even in products, different heat stabilizers are often used, and different kinds of heat stabilizers may react with each other to cause discoloration.

[0006] Further, in the case of waste resin of a stop resin, even if an attempt is made to pulverize and use it as a recycled material, since a large amount of a heat stabilizer is added to the stop resin, the resulting molded product is a new resin. Physical properties such as tensile strength and tensile elongation are inferior to those in the case of using raw materials, and may not be practical.

[0007]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention makes it possible to effectively utilize a derivative or waste material of a vinyl chloride resin molded product or a waste material of a stop resin which has been conventionally discarded or incinerated. The purpose is to provide a three-layer tube that can be used.

[0008]

In order to achieve such an object, a three-layer tube according to the first aspect of the present invention (hereinafter referred to as "three-layer tube of the first aspect") is provided. A middle layer made of a hard vinyl chloride resin containing a recycled material obtained from a derivative of a vinyl chloride resin molded article and / or waste material, and a recycled material free layer provided so as to cover the outer peripheral surface of the intermediate layer. An outer layer made of a hard vinyl chloride resin and an inner layer made of a hard vinyl chloride resin containing no recycled material and provided so as to cover the inner peripheral surface of the intermediate layer were provided.

The three-layer pipe according to the second aspect of the present invention (hereinafter referred to as "three-layer pipe of the second aspect") is a heat stabilizer used at the end of extrusion molding of a vinyl chloride resinous product. The intermediate layer made of vinyl chloride resin containing recycled material obtained from waste resin of stop resin added more than the product, and hard chloride containing no recycled material provided so as to cover the outer peripheral surface of this intermediate layer An outer layer made of a vinyl resin and an inner layer made of a hard vinyl chloride resin containing no recycled material and provided so as to cover the inner peripheral surface of the intermediate layer were provided.

In the three-layer tube of the first aspect, the mixing ratio of the recycled material in the intermediate layer is not particularly limited, but is preferably about 20 to 100% based on a new vinyl chloride resin. In the three-layer tube of claim 2, the blending ratio of the recycled material in the intermediate layer is not particularly limited, but is preferably about 50 to 300% with respect to a new vinyl chloride resin.

Further, in the three-layer pipe of the first and second aspects, the intermediate layer may be in a foamed state.
When the intermediate layer is foamed, the ratio of the intermediate layer to the total thickness is not particularly limited, but is preferably about 30 to 85%.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the three-layer tube of claim 1.

As shown in FIG. 1, the three-layer tube 1 has an intermediate layer 12, an outer layer 11 provided to cover the outer peripheral surface of the intermediate layer 12, and an inner layer of the intermediate layer 12. And the inner layer 13 provided on the inner side. The mid layer 12
It is formed of a vinyl chloride resin obtained by mixing a derivative of a vinyl chloride resin molded product and a recycled material produced by grinding waste materials with a new vinyl chloride resin material.

The outer layer 11 and the inner layer 13 are formed of a novel vinyl chloride resin containing no recycled material. The three-layer tube 1 is manufactured as follows.

First, a raw material for an intermediate layer is obtained by cold blending a new vinyl chloride resin raw material and a recycled raw material obtained by pulverizing a derivative of vinyl chloride resin molded product and waste material to obtain a raw material for an intermediate layer. A new vinyl chloride resin raw material is prepared as a raw material for the inner layer. Next, each raw material is filled in an extruder and continuously formed on the outer layer 11 and the intermediate layer 1.
The three-layer tube 1 composed of the inner layer 2 and the inner layer 13 is formed.

As described above, according to the three-layer tube 1, since the outer peripheral surface and the inner peripheral surface of the intermediate layer 12 are covered by the outer layer 11 and the inner layer 13, the intermediate layer 12 is discolored. Also, the outer shape is concealed by the outer layer 11 and the inner layer 13 formed of a new vinyl chloride resin raw material, and has the same appearance as a single-layer tube using only a normal new vinyl chloride resin raw material. Moreover, since recycled materials can be used for the intermediate layer 12, derived products and waste materials can be recycled. Therefore, the cost can be reduced as compared with a single-layer pipe using only a new vinyl chloride resin raw material.

FIG. 2 shows an embodiment of the three-layer tube according to the second aspect. As shown in FIG. 2, this three-layer tube 1 '
Is a method in which the intermediate layer 12 'is cold-blended with a new vinyl chloride resin raw material and a recycled raw material obtained by pulverizing waste resin of the stop resin, and the raw material for the intermediate layer is used. Except for this, it is the same as the three-layer tube 1 described above.

[0018]

Embodiments of the present invention will be described below in more detail.

(Example 1) A waste material of a PVC pipe for sewage (containing a lead-based heat stabilizer) and a waste material of a PVC pipe for water service (containing a tin-based heat stabilizer) were pulverized using a commercially available cutter mill.
Each of the pulverized products was passed through a φ5 mm screen, and the passed products were obtained as recycled materials. The recycled raw material thus obtained, a new vinyl chloride resin raw material (having a degree of polymerization of 1000), a lead-based heat stabilizer, a polyethylene-based lubricant, and calcium carbonate were cold-mixed in the proportions shown in Table 1 below. The raw material for the intermediate layer was obtained by blending.

[0020]

[Table 1]

Next, using the thus obtained raw material for the intermediate layer and a new vinyl chloride resin raw material (with a degree of polymerization of 1000) for the outer layer and the inner layer, a twin-screw conical extruder was used. Thus, a three-layer tube having an outer diameter and a wall thickness as shown in FIG.
Examining the appearance, moldability and tensile strength of the obtained three-layer tube,
The results are shown in Table 2.

[0022]

[Table 2]

From Table 2 above, according to the three-layer tube of the present invention,
Good appearance and moldability, and tensile strength is also JIS K 674
It is well understood that the value of 480 kgf / cm ² defined in No. 3 can be satisfied.

(Example 2) A block-shaped waste material of the stop resin having the composition shown in Table 3 was pulverized using a commercially available cutter mill, and the pulverized product was passed through a screen with a diameter of 5 mm. Obtained. The thus obtained recycled raw material, a vinyl chloride resin having a polymerization degree of 1000, a stearic acid-based lubricant and calcium carbonate were cold-blended in the mixing ratio shown in Table 4 to obtain a raw material for an intermediate layer.

[0025]

[Table 3]

[0026]

[Table 4]

Next, the raw material for the intermediate layer obtained in this manner and the new vinyl chloride resin raw material (with a degree of polymerization of 1,000) for the outer layer and the inner layer were used and a twin-screw conical extruder was used. Thus, a three-layer tube having an outer diameter and a wall thickness as shown in FIG.
The specific gravity, expansion ratio, appearance, and moldability of the intermediate layer of the obtained three-layer tube were examined, and the results are shown in Table 5.

[0028]

[Table 5]

From Table 5 above, it can be seen that the appearance and the moldability are good, and that the heat stabilizer is newly added by using a recycled material obtained from the waste resin of the stop resin containing a large amount of the heat stabilizer in the intermediate layer. It can be clearly understood that the molding can be sufficiently performed only by using the heat stabilizer in the regenerated raw material without using the heat stabilizer.

[0030]

As described above, the three-layer pipe according to the first aspect of the present invention can effectively utilize a derivative or a waste material of a vinyl chloride resin molded product which has been conventionally discarded or incinerated. The three-layer pipe according to the second aspect can effectively use the waste material of the stop resin that has been conventionally discarded or incinerated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the three-layer tube of claim 1;

FIG. 2 is a sectional view showing an embodiment of a three-layer tube according to the second embodiment.

[Explanation of symbols]

 1,1 'three-layer tube 11 outer layer 12,12' middle layer 13 inner layer

Claims (2)

[Claims] An intermediate layer made of a hard vinyl chloride resin containing a recycled material obtained from a derivative of a vinyl chloride resin molded article and / or a waste material, and a recycled layer provided so as to cover an outer peripheral surface of the intermediate layer. A three-layer tube comprising: an outer layer made of a hard vinyl chloride resin containing no raw material; and an inner layer made of a hard vinyl chloride resin containing no recycled material provided so as to cover an inner peripheral surface of the intermediate layer. 2. An intermediate layer made of a vinyl chloride resin containing a recycled material obtained from waste resin of a stop resin to which a heat stabilizer used at the end of extrusion molding of a vinyl chloride resin product is added in a larger amount than the product, An outer layer made of hard vinyl chloride resin containing no recycled material provided so as to cover the outer peripheral surface of the intermediate layer, and a hard vinyl chloride resin containing no recycled material provided so as to cover the inner circumferential surface of the intermediate layer A three-layer tube having an inner layer made of stainless steel.