Resin pipe

Abstract

The present invention aims to provide a resin pipe that can reduce the environmental load and maintain the same appearance and physical properties as conventional resin pipes that use only virgin resin. The present invention relates to a resin pipe containing one or more recycled polyolefin resins.

Description

[Technical Field]

[0001] The present invention relates to a resin pipe. [Background technology]

[0002] In recent years, plastic piping, which is easy to install and does not corrode, has come to be used as pipes for supplying hot and cold water. The raw materials used for these pipes include polyolefin resin, polyester resin, and polyphenylene ether resin.

[0003] Furthermore, in recent years, there has been an increasing demand for recycling plastics in order to reduce the environmental impact, and various methods for recycling plastics have been investigated.

[0004] For example, Patent Document 1 discloses a thermoplastic resin composition containing a polyester-based resin (A) and 0.1 to 15 mass % of an ethylene-based copolymer (B) containing an unsaturated carboxylic acid anhydride comonomer, and a molded article obtained by molding the thermoplastic resin composition, and describes that the polyester-based resin (A) and the like can be recycled resins. Furthermore, Patent Document 2 discloses a pipe material made of a polyphenylene ether resin composition containing a polyphenylene ether resin and a polystyrene resin, with the aim of providing a recyclable pipe material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-147178 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-277656 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to reduce the environmental load, it is conceivable to use recycled resin instead of virgin resin (non-recycled resin) that constitutes the resin pipe, as in Patent Document 1. However, resin pipes made from recycled resins may have significantly inferior appearances or significantly reduced physical properties compared to conventional resin pipes made from only virgin resins.

[0007] Therefore, the present invention aims to solve the problems of the above-mentioned conventional technology, to provide a resin pipe that can reduce the environmental burden and maintain the same appearance and physical properties as conventional resin pipes that use only virgin resin. [Means for solving the problem]

[0008] The resin pipe of the present invention, which solves the above problems, has the following essential configuration.

[0009] [1] Plastic pipe containing one or more recycled polyolefin resins. The resin pipe described in [1] above can reduce the environmental impact and maintain the same appearance and physical properties as conventional resin pipes made only of virgin resin.

[0010] [2] The resin pipe according to [1], further comprising a non-recycled polyolefin resin. The resin pipe described in [2] above can reduce the environmental impact and maintain the same appearance and physical properties as conventional resin pipes made only from virgin resin.

[0011] [3] The resin pipe according to [1] or [2], wherein the recycled polyolefin resin contains recycled polybutene. The resin pipe described in [3] above can reduce the environmental impact and maintain the same appearance and physical properties as conventional resin pipes made only of virgin resin.

[0012] [4] The plastic pipe according to [3], wherein the recycled polybutene is polybutene recycled from plastic piping. The resin pipe described in [4] above can reduce the amount of resin piping discarded and reduce the environmental impact.

[0013] [5] The resin pipe according to [3], wherein the recycled polybutene is polybutene recycled from the innermost layer of a cold water / hot water supply pipe having multiple layers. The resin pipe described in [5] above can reduce the waste of the innermost layer of the cold water supply / hot water supply pipe, thereby reducing the environmental burden.

[0014] [6] The resin pipe according to any one of [3] to [5], wherein the recycled polybutene content is 10% by mass or more based on the total amount of the recycled polyolefin resin. The resin pipe described in [6] above maintains its appearance and physical properties to a higher degree while reducing the environmental load.

[0015] [7] The resin pipe according to any one of [3] to [6], wherein the recycled polyolefin resin further contains recycled polyethylene. The resin pipe described in [7] above can reduce the environmental impact and maintain the same appearance and physical properties as conventional resin pipes made only from virgin resin.

[0016] [8] The plastic pipe according to any one of [1] to [7], wherein the content of the recycled polyolefin resin is 1% by mass or more and 50% by mass or less based on the total amount of resin contained in the plastic pipe. The resin pipe described in [8] above can reduce the environmental load while maintaining the same appearance and physical properties as conventional resin pipes made only from virgin resin.

[0017] [9] The resin pipe according to any one of [1] to [8], which is for use as a water supply / hot water supply pipe. The resin pipe described in [9] above maintains the same appearance and physical properties as conventional resin pipes made only from virgin resin, and is therefore suitable for use as a cold water / hot water supply pipe.

[0018]

[10] A resin pipe according to any one of [1] to [8], which is for a water supply / hot water pipe used as a layer other than the innermost layer of a water supply / hot water pipe having multiple layers. The resin pipe described in

[10] above maintains the same appearance and physical properties as conventional resin pipes made only of virgin resin, and is therefore suitable for use as a water supply / hot water pipe other than the innermost layer of a water supply / hot water pipe having multiple layers. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a resin pipe that can reduce the environmental load and maintain the same appearance and physical properties as conventional resin pipes that use only virgin resin. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The resin pipe of the present invention will be described in detail below by way of example based on embodiments thereof.

[0021] <Definition> The compounds described herein may be derived in part or in whole from fossil sources, biological sources such as plant sources, recycled sources such as used tires, or a mixture of two or more of fossil, biological, and recycled sources.

[0022] "Recycled resin" refers to resin that has been recycled. "Virgin resin" refers to resin that has not been recycled (non-recycled resin). "Recycled polyolefin resin" refers to a resin that has been recycled and whose main repeating units are olefin units. "Main repeating units" means that the main repeating units account for 51% or more of the repeating units. "Non-recycled polyolefin resin" refers to a resin that has not been recycled and whose main repeating unit is an olefin unit.

[0023] <Resin pipe> The resin pipe of this embodiment is characterized by containing one or more recycled polyolefin resins. The resin pipe contains recycled polyolefin resin in place of at least a portion of virgin resin, which reduces the environmental impact compared to conventional resin pipes that use only virgin resin. Furthermore, while containing recycled polyolefin resin, the resin pipe maintains the same appearance and physical properties as resin pipes that use only virgin resin.

[0024] The resin pipe contains a resin. As described above, the resin contained in the resin pipe of this embodiment contains one or more recycled polyolefin resins. The resin pipe may also contain a non-recycled polyolefin resin described below, or may contain other resins and optional additives.

[0025] The resin contained in the resin pipe preferably has a melt flow rate (MFR), which is a measure of molecular weight, of 0.3 g / 10 min or more. From the viewpoint of molding stability, the MFR is preferably 5.0 g / 10 min or less, and more preferably 3.0 g / 10 min or less. The melt flow rate is a value measured in accordance with JIS K 7210-1999 and JIS K 6922-1 at 190°C under a load of 2.16 kg.

[0026] The resin contained in the resin pipe preferably has an elastic modulus of 130 MPa or more and 780 MPa or less. When the elastic modulus is within this range, the flexibility of the covering material is ensured. The elastic modulus is preferably 130 MPa or more, and more preferably 360 MPa or less. The elastic modulus is a value measured in accordance with JIS K7161.

[0027] In addition, the resin contained in the resin pipe has a density of 0.900 g / cm3 in order to ensure good strength. 3 It is preferable that the density is 0.910 g / cm or more. 3On the other hand, the resin contained in the resin pipe has a density of 0.95 g / cm or more from the viewpoint of flexibility of the product. 3 It is preferable that:

[0028] Furthermore, from the viewpoint of ease of use when using a resin pipe, it is preferable that the repulsive force that causes the resin pipe to return to its original state (the shape when no force is applied) when contracted in the axial direction is small. The repulsive force is preferably 45 N or less, and more preferably 30 N or less. However, depending on the mode of use, a certain degree of repulsive force is also required, so the repulsive force is preferably 5 N or more, and more preferably 10 N or more. The repulsive force can be measured using a push-pull gauge.

[0029] (recycled polyolefin resin) The resin pipe of this embodiment contains one or more recycled polyolefin resins. The recycled polyolefin resin is a recycled resin whose main repeating unit is an olefin unit. When the resin pipe contains the recycled polyolefin resin, the amount of virgin resin used can be reduced, thereby reducing the environmental load.

[0030] Examples of recycled polyolefin resins include those obtained by material recycling, in which used polyolefin resin (e.g., used polybutene, used polyethylene) molded articles are crushed, washed, and reused, and those obtained by chemical recycling (chemical decomposition method). Chemical recycling involves chemically decomposing recovered used polyolefin resin (e.g., used polybutene, used polyethylene) molded articles, returning them to the raw material level, and resynthesizing polyolefin resin (e.g., recycled polybutene, recycled polyethylene, etc.).

[0031] Furthermore, the recycled polyolefin resin may be recycled from pre-consumer products such as waste or defective products (i.e., scrap materials obtained during the production of extrusion molded products of polyolefin resin) generated in the process of molding a molded product from polyolefin resin, or recycled from products that have been distributed on the market as molded products and then collected as waste plastic after consumption, i.e., recycled from collected products that have been distributed on the market and then consumed.

[0032] Examples of polyolefins in recycled polyolefin-based resins include polybutene, polyethylene (low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc.), polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. These resins may be used alone or in combination of two or more. Among these, polybutene and polyethylene are preferred as polyolefins. That is, recycled polybutene and recycled polyethylene are preferred as recycled polyolefin-based resins.

[0033] In the resin pipe of this embodiment, the content of recycled polyolefin resin is preferably 1% by mass or more and 50% by mass or less, based on the total resin contained in the resin pipe. When the content of recycled polyolefin resin is within this range, the environmental impact can be reduced while maintaining the same appearance and physical properties as conventional resin pipes made only of virgin resin. From the viewpoint of reducing the environmental impact, the content of recycled polyolefin resin is more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total resin contained in the resin pipe. Furthermore, from the viewpoint of maintaining the same appearance and physical properties as conventional resin pipes, the content of recycled polyolefin resin is more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total resin contained in the resin pipe.

[0034] The recycled polyolefin resin preferably contains recycled polybutene. By including recycled polybutene in the resin pipe of this embodiment, the recycled resin can be used to reduce the environmental impact. Furthermore, since polybutene has excellent durability, the resin pipe has excellent abrasion resistance and impact resistance.

[0035] Recycled polybutene can be obtained by recycling various polybutene molded products, including, but not limited to, polybutene-containing resin piping (resin pipes), films, sheets, and the like. Furthermore, polybutene is used as a pipe (polybutene pipe) due to its excellent durability. By using recycled polybutene recycled from polybutene pipe as the raw material for the resin pipe of this embodiment, it is possible to recycle the same type of product from pipe to pipe. Therefore, it is particularly preferable that the recycled polybutene contained in the resin pipe of this embodiment is polybutene recycled from resin piping. Recycled materials from the same type of product tend to contain fewer components unnecessary for the product, and are therefore less likely to significantly change performance when applied to recycled products than when recycled materials from other types of products are used. Note that, in this specification, the resin pipe may have a single-layer structure or a multi-layer structure.

[0036] Furthermore, the recycled polybutene is preferably polybutene recycled from the innermost layer of a multi-layered water supply / hot water pipe, which is used for the innermost layer of the pipe due to its excellent abrasion resistance and impact resistance, as mentioned above.

[0037] The recycled polybutene content is preferably 1% by mass or more and less than 100% by mass of the entire recycled polyolefin resin. The recycled polybutene content is more preferably 10% by mass or more, and even more preferably 20% by mass or more. The recycled polybutene content is also preferably less than 100% by mass.

[0038] In the resin pipe of this embodiment, the recycled polyolefin resin preferably contains recycled polyethylene and polypropylene. Furthermore, the recycled polyolefin resin of this embodiment more preferably contains recycled polyethylene in addition to recycled polybutene. By including recycled polyethylene, the resin pipe can have excellent drawdown resistance (shape retention in a molten state) during pipe production and excellent extrusion moldability.

[0039] Recycled polyethylene can be obtained by recycling various polyethylene molded products. Examples of recycled polyethylene molded products include, but are not limited to, polyethylene-containing resin pipes, films, sheets, etc.

[0040] The content of recycled polyethylene is not particularly limited, but is preferably less than the content of recycled polybutene.

[0041] In the resin pipe of this embodiment, the recycled polyolefin resin may include other recycled polyolefin resins (hereinafter simply referred to as "other recycled polyolefin resins") other than the above-mentioned recycled polybutene and recycled polyethylene. Examples of other recycled polyolefin resins include, but are not limited to, recycled polypropylene and recycled ethylene-propylene copolymer. The content of other recycled polyolefin resins may be 1% by mass or more based on the total recycled polyolefin resins, and is preferably 20% by mass or less from the viewpoint of maintaining physical properties and appearance.

[0042] (Non-recycled polyolefin resin) The resin pipe of this embodiment may further contain a non-recycled polyolefin resin. The non-recycled polyolefin resin is a polyolefin resin that has not been recycled. When the resin pipe further contains a non-recycled polyolefin resin, deterioration in appearance and physical properties can be suppressed.

[0043] Non-recycled polyolefin resins include, but are not limited to, polyethylene, polybutene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. Examples of polyethylene include ethylene homopolymers and copolymers (e.g., binary or terpolymers) of ethylene and other comonomers copolymerizable with ethylene, and one type may be used alone or two or more types may be used in combination. In addition, commercially available products may be used as the non-recycled polyolefin resin.

[0044] The other comonomer copolymerizable with ethylene is not particularly limited, but examples thereof include α-olefins, vinyl compounds, etc. The other comonomers may be used alone or in combination of two or more.

[0045] Among the above-mentioned non-recycled polyolefin resins, the non-recycled polyolefin resin preferably contains polyethylene. When the non-recycled polyolefin resin contains polyethylene, the proportion of polyethylene is preferably 80% by mass or more, more preferably 90% by mass or more, and may even be 100% by mass, based on the total non-recycled polyolefin resin.

[0046] For example, from the viewpoint of ensuring good heat resistance, the melting point of the polyethylene is preferably 100° C. or higher, and more preferably 105° C. or higher. On the other hand, from the viewpoint of the flexibility of the product, the melting point of the polyethylene is preferably 130° C. or lower. In order to ensure good strength, the density of the polyethylene is 0.900 g / cm 3It is preferable that the density is 0.910 g / cm or more. 3 On the other hand, from the viewpoint of flexibility of the product, the density of the polyethylene is preferably 0.940 g / cm or more. 3 It is preferable that:

[0047] The content of the non-recycled polyolefin resin is preferably 1% by mass or more and 99% by mass or less of the total resin contained in the resin pipe, and more preferably 15% by mass or more and 50% by mass or less of the total resin.

[0048] In the resin pipe of this embodiment, the total content of recycled polyolefin resin and non-recycled polyolefin resin relative to the total resin (hereinafter also referred to as "total polyolefin content") is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 100 mass%, i.e., it is composed essentially of polyolefin resin only.

[0049] (Other ingredients) The resin pipe of this embodiment may contain other resins, additives, etc., as needed, in addition to the recycled polyolefin resin and non-recycled polyolefin resin described above.

[0050] Examples of the other resins include polyvinyl chloride, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polyamide resins such as nylon 6 and nylon 66. The content of the other resins is not particularly limited, but can be 1% by mass or more and 10% by mass or less. More preferably, the composition is substantially free of other resins.

[0051] Examples of additives include known additives such as antioxidants, die-cast inhibitors, ultraviolet absorbers, light stabilizers, antistatic agents, crosslinking agents, lubricants, antiblocking agents, processability improvers, fillers, dispersants, anti-foaming agents, colorants, etc. The content of the additives is not particularly limited, but can be 0.1% by mass or more and 5% by mass or less.

[0052] In another preferred embodiment, the resin pipe is characterized by containing a recycled polyolefin resin and a non-recycled polyolefin resin. Because the resin pipe contains recycled polyolefin resin, it can reduce the environmental impact compared to conventional resin pipes that use only virgin resin. Furthermore, the resin pipe can suppress deterioration in appearance and physical properties equivalent to those of resin pipes that use only virgin resin. Therefore, the resin pipe can reduce the environmental impact and maintain the appearance and physical properties equivalent to those of conventional resin pipes that use only virgin resin. The above-mentioned descriptions of recycled polyolefin resins and non-recycled polyolefin resins can be used to explain the components that may be contained in recycled polyolefin resins and non-recycled polyolefin resins, as well as in resin pipes.

[0053] The shape of the resin pipe is not particularly limited and can have a known structure, but is preferably a corrugated shape in which annular peaks that convex radially outward from the resin pipe and annular valleys that concave radially outward are alternately and continuously formed in the axial direction of the resin pipe. Furthermore, when the resin pipe is used as a coating layer of a composite pipe when used as part of a composite pipe (i.e., when used as a coating material for a composite pipe), it is particularly preferable that the shape of the resin pipe be a corrugated shape in which annular peaks that convex radially outward from the resin pipe and annular valleys that concave radially outward are alternately and continuously formed in the axial direction of the resin pipe.

[0054] The thickness of the resin pipe or the covering material is preferably 0.3 mm or more at the thinnest part and 0.4 mm or less at the thickest part.

[0055] The diameter of the resin pipe (outer diameter of the outermost part) is not particularly limited, but can be set within the range of 13 mm or more and 130 mm or less, for example.

[0056] (Manufacturing method of resin pipes) The resin pipe of this embodiment can be appropriately produced by kneading a resin composition containing a resin and the like by a known method and molding the resin composition. Here, examples of the molding method include extrusion molding and injection molding, and among these, extrusion molding is preferred. For example, the resin pipe of this embodiment may be manufactured by pre-mixing the recycled polyolefin resin, and if necessary, a resin such as a non-recycled olefin resin, and selected additives to prepare a mixture, and then supplying the mixture to a molding machine for melt molding. Alternatively, the recycled polyolefin resin, and if necessary, a resin such as a non-recycled olefin resin, and selected additives may be separately charged into a molding machine in a predetermined blending ratio, and melt molded while being kneaded. Here, for preparing the mixture, i.e., for kneading, a single-screw extruder (single-screw extruder), a twin-screw extruder, a twin-screw kneader, etc. For molding, any molding machine such as an extrusion molding machine or an injection molding machine may be used, and the type is appropriately selected depending on the shape of the desired resin pipe.

[0057] (Application) The resin pipe of this embodiment is not particularly limited, but can be used for, for example, a water supply / hot water supply pipe, an air conditioning / heating pipe, a floor heating pipe, a hot spring water supply pipe, a geothermal water pipe, a pipe from a solar heat collector, a roof snow melting pipe, a road heating pipe, various plant pipes such as those in a chemical plant, a heat exchanger pipe, etc. Among these, the resin pipe of this embodiment is preferably used as a water supply / hot water supply pipe. Furthermore, some water supply / hot water pipes have multiple layers (for example, an outermost layer, an intermediate layer, an innermost layer, etc.), and when the resin pipe of this embodiment is used in such a water supply / hot water pipe, it is preferable that the resin pipe of this embodiment is used in a layer other than the innermost layer of the water supply / hot water pipe. In other words, it is preferable that the resin pipe of this embodiment is used for a water supply / hot water pipe that is used in a layer other than the innermost layer of a water supply / hot water pipe having multiple layers.

[0058] The resin pipe of this embodiment is more preferably used as a part of a composite pipe. Examples of composite pipes include a composite pipe having an innermost layer, an outermost layer which is a coating layer, and an intermediate layer disposed between the innermost layer and the outermost layer. In such composite pipes, the resin pipe of this embodiment is preferably used as a layer other than the innermost layer, and is particularly preferably used as the coating layer which is the outermost layer of the composite pipe.

[0059] Another embodiment is a composite pipe including the resin pipe of this embodiment. The composite pipe has multiple layers, and preferably includes the resin pipe of this embodiment as the outermost layer of a composite pipe including an innermost layer, an outermost layer which is a coating layer, and an intermediate layer disposed between the innermost layer and the outermost layer. Because this composite pipe includes the resin pipe of this embodiment containing recycled polyolefin resin, it can reduce the environmental impact compared to conventional composite pipes and has the same appearance and physical properties as conventional composite pipes. [Example]

[0060] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0061] <Making resin pipes> Resins were kneaded according to the compounding compositions shown in Table 1, and the kneaded resin was extruded from an extruder into a cylindrical shape to form a resin pipe.

[0062] <Evaluation of resin pipes> The resin pipes produced in the examples and comparative examples were evaluated as follows.

[0063] (1) Color difference The appearance of the resin pipe was evaluated based on the color difference from the resin pipe of Comparative Example 1, which did not contain recycled polyolefin resin. Each resin pipe was subjected to color measurement using a colorimeter (manufactured by Konica Minolta, Inc.). From the obtained values, the color difference (ΔE * ab) was calculated. ΔE * ab = (ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2 〕 1 / 2 If the color difference with the resin pipe of Comparative Example 1, which does not contain recycled polyolefin resin, was 5 or less, it was determined that the appearance was maintained compared to the resin pipe not containing recycled polyolefin resin (i.e., the resin pipe containing only virgin resin). The evaluation results are shown in Table 1.

[0064] (2) Repulsion force To evaluate the physical properties of the resin pipe, the repulsive force was measured using a push-pull gauge (manufactured by IMADA). The repulsive force is expressed as an index, with the evaluation result of Comparative Example 1 being 100. When the evaluation result of the existing product (Comparative Example 1) is taken as 100, the repulsive force is preferably 150 or less. The evaluation results are shown in Table 1.

[0065] [Table 1]

[0066] *1 Recycled polyolefin resin: Polybutene 20% by mass, polyethylene 78-80% by mass, polypropylene (if included) 0-2% by mass *2 Non-recycled polyolefin resin: polyethylene

[0067] Table 1 shows that even resin pipes containing recycled polyolefin resin maintain their appearance and physical properties compared to resin pipes that do not contain recycled polyolefin resin. [Industrial Applicability]

[0068] According to the present invention, it is possible to provide a resin pipe that can reduce the environmental load and maintain the same appearance and physical properties as conventional resin pipes that use only virgin resin.

[0069] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to goals such as "No. 9 - Build infrastructure for industry and technological innovation" and "No. 12 - Responsible consumption and production."

Claims

1. A resin pipe comprising one or more recycled polyolefin resins.

2. The resin pipe according to claim 1 , further comprising a non-recycled polyolefin resin.

3. The resin pipe according to claim 1 or 2, wherein the recycled polyolefin resin contains recycled polybutene.

4. The resin pipe according to claim 3, wherein the recycled polybutene is polybutene recycled from a resin pipe.

5. 4. The resin pipe according to claim 3, wherein the recycled polybutene is polybutene recycled from the innermost layer of a cold / hot water supply pipe having a plurality of layers.

6. The resin pipe according to claim 3, wherein the recycled polybutene content is 10% by mass or more based on the total amount of the recycled polyolefin resin.

7. The resin pipe according to claim 3 , wherein the recycled polyolefin resin further contains recycled polyethylene.

8. The resin pipe according to claim 1 or 2, wherein the content of the recycled polyolefin resin is 1% by mass or more and 50% by mass or less based on the total resin contained in the resin pipe.

9. 3. The resin pipe according to claim 1, which is used as a water supply pipe.

10. 3. The resin pipe according to claim 1, which is used for a water / hot water supply pipe other than the innermost layer of a water / hot water supply pipe having a plurality of layers.

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