A multi-layer PVC-O pipe with excellent mechanical properties

Abstract

The present application relates to a multilayer PVC-O pipe with excellent mechanical properties, and relates to the field of polymer materials. The outermost layer of the PVC-O pipe is a PVC main layer, and the inner layer is an EVA layer. Among them, the inner layer has certain strength and toughness, and the main PVC layer also has sufficient strength. The hot melts between the layers have good compatibility and can be formed in one time through a multilayer co-extrusion process, and have the conditions for large-scale production and preparation. At the same time, in order to compensate for the situation that the toughness of the inner layer is too high, a carbon fiber or glass fiber braid is provided in the inner layer to play a better role in buffering the internal and external pressures.

Description

Technical Field

[0001] The invention relates to a multilayer PVC-O pipe with excellent mechanical properties, belonging to the field of polymer materials. Background Art

[0002] Biaxially oriented polyvinyl chloride (PVC-O) pipes are generally made by axially stretching and radially stretching PVC-U billet pipes produced by extrusion, so that the PVC long-chain molecules in the pipes are arranged regularly in the biaxial direction, obtaining a new type of PVC pipe with high strength, high toughness, high impact resistance and fatigue resistance. Its performance is far superior to that of PVC-U pipes. The development of PVC-O pipes can greatly save raw material resources, reduce costs, and improve product performance, with obvious economic and social benefits.

[0003] Since PVC-O pipes need to be biaxially stretched during production, PVC-U blanks must have good toughness and plasticization. For this reason, most patents improve the toughness of PVC pipes by adding ACR to PVC, but the improvement is limited. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a multi-layer PVC-O pipe with excellent mechanical properties, which is prepared by integrated molding of the compatibility between the layers. The inner layer has certain strength and toughness, and the main PVC layer also has sufficient strength. The hot melt between the layers has good compatibility and can be formed in one step through a multi-layer co-extrusion process, which has the conditions for large-scale production and preparation. At the same time, in order to compensate for the excessive toughness of the inner layer, a carbon fiber or glass fiber braid is provided in the inner layer to play a better role in buffering the internal and external pressures.

[0005] The present invention is achieved through the following technical solutions:

[0006] The invention comprises: a multi-layer PVC-O pipe with excellent mechanical properties, characterized in that the outermost layer of the PVC-O pipe is a PVC main body layer, and the inner layer is an EVA layer.

[0007] The PVC main body layer contains 0-30% of crushed and recycled phenolic resin or epoxy resin (with a particle size of 3-5 microns) and no more than 15% of EVA.

[0008] The inner EVA layer is an EVA layer lined with a carbon fiber or glass fiber braid.

[0009] The pipe is obtained by biaxially stretching a PVC-U pipe blank and then cooling and shaping it.

[0010] Compared with the existing technology, this technical system has good compatibility of each layer of melt through formula design, can be formed in one step through multi-layer co-extrusion technology, and has the conditions for large-scale production. The pipe provided by this technology has excellent mechanical properties, good strength and toughness, and this system uses ground waste phenolic or epoxy resin to reinforce the outer layer, and the inner layer uses carbon fiber or glass fiber braid to achieve structural support. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the PVC-O pipe of the present invention. DETAILED DESCRIPTION

[0012] Example 1

[0013] The PVC main body layer contains 15% EVA, and the layer contains 15% crushed and recycled phenolic resin with a particle size of D 50 =2 microns, the inner layer is an EVA layer lined with a carbon fiber braid, which is formed by multi-layer co-extrusion. After thermoforming and biaxial stretching, the tensile strength of the tube is tested to be 54.1 MPa.

[0014] The following is a comparative example to illustrate the effect of Example 1.

[0015] As a control, when other conditions in Example 1 remain unchanged, the content of the crushed and recovered phenolic resin in the PVC layer in Example 1 is adjusted to 5%, the particle size remains unchanged, and the tensile strength of the sample reaches 49.7 MPa; when other conditions in Example 1 remain unchanged, the crushed and recovered phenolic resin in the PVC layer in Example 1 is removed, and the tensile strength of the sample reaches 37.7 MPa; when other conditions in Example 1 remain unchanged, the carbon fiber braid in the inner EVA layer in Example 1 is adjusted to a glass fiber braid, and the tensile strength of the sample reaches 51.7 MPa.

[0016] Example 2

[0017] The main PVC layer contains 15% EVA and 30% crushed and recycled phenolic resin with a particle size of D 50 =5 microns, the inner layer is an EVA layer lined with a carbon fiber braid. After thermoforming and biaxial stretching, the tensile strength of the pipe is tested to be 54.3 MPa.

[0018] The following is a comparative example to illustrate the effect of Example 2.

[0019] As a control, when other conditions in Example 2 remain unchanged, the particle size of the phenolic resin recovered by crushing in Example 2 is adjusted to D 90=5 microns, the tensile strength of the sample reaches 49.7 MPa; when other conditions in Example 2 remain unchanged, the EVA in the PVC layer in Example 2 is removed, and the tensile strength of the sample reaches 59.5 MPa.

[0020] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A multilayer PVC-O pipe with excellent mechanical properties, characterized in that: The PVC-O pipe is composed of a PVC main layer and an EVA layer; the outermost layer of the PVC-O pipe is the PVC main layer, and the inner layer is the EVA layer; The PVC main body layer contains 15%-30% of crushed and recycled phenolic resin particles or epoxy resin particles, and contains 15% of EVA, and the rest is PVC; the inner EVA layer is an EVA layer lined with a carbon fiber braid, and the carbon fiber braid is in the EVA layer; The pipe is obtained by biaxially stretching a PVC-U pipe blank and then cooling and shaping it.

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