A PE-RT oxygen barrier pipe with excellent performance and its preparation method

Abstract

The present invention discloses a PE-RT oxygen barrier pipe with excellent performance and a preparation method thereof, which includes an inner layer and an outer layer. The inner layer is a heat-resistant polyethylene layer, and the outer layer is an oxygen barrier layer. The outer layer is prepared from ethylene-vinyl alcohol copolymer, basalt fiber, maleic anhydride grafted EPDM and hot melt adhesive in a certain proportion. The preparation method of the PE-RT oxygen barrier pipe is as follows: S1. Add heat-resistant polyethylene into a single-screw extruder, extrude and form an inner pipe; S2. Mix ethylene-vinyl alcohol copolymer, basalt fiber, maleic anhydride grafted EPDM and hot melt adhesive evenly, and then transfer them into a single-screw extruder for outer layer auxiliary extrusion and apply them to the surface of the inner pipe to form the PE-RT oxygen barrier pipe. The PE-RT oxygen barrier pipe has an apparent smooth surface, no crystal point impurities, and has good oxygen barrier performance and mechanical properties, and other related properties meet the relevant requirements of GB / T 28799.2-2020.

Description

Technical Field

[0001] The present invention relates to the technical field of PE pipe production, and specifically relates to a PE-RT oxygen barrier pipe with excellent performance and a preparation method thereof. Background Art

[0002] Heat-resistant polyethylene (PE-RT) pipes have been widely used as floor heating pipes in the field of building heating and ventilation. However, during the production of PE-RT oxygen barrier floor heating pipes, on the one hand, the ethylene-vinyl alcohol (EV-OH) oxygen barrier material on the surface has poor compatibility with PE-RT, resulting in phenomena such as wrinkling, crystal points or agglomeration on the appearance, seriously affecting the production, popularization and application of products. On the other hand, the oxygen barrier performance and strength of the oxygen barrier pipe are relatively poor, unable to meet the growing performance requirements. Summary of the Invention

[0003] Based on the above-mentioned prior art, the present invention provides a PE-RT oxygen barrier pipe with excellent performance and a preparation method thereof. The oxygen barrier pipe has a smooth appearance, no crystal point impurities, and has good oxygen barrier performance and mechanical properties, and other related properties all meet the relevant requirements of GB / T 28799.2-2020.

[0004] The preparation method of the oxygen barrier pipe is simple, easy to operate, and has a low preparation cost.

[0005] The technical solution adopted to achieve the above object of the present invention is as follows:

[0006] A PE-RT oxygen barrier pipe with excellent performance, including an inner layer and an outer layer. The inner layer is a heat-resistant polyethylene layer, and the outer layer is an oxygen barrier layer;

[0007] The oxygen barrier layer is prepared from the following raw materials in parts by mass:

[0008]

[0009] Further, the hot melt adhesive is a special polyolefin hot melt adhesive.

[0010] A preparation method of a PE-RT oxygen barrier pipe with excellent performance, including the following steps:

[0011] S1. Add heat-resistant polyethylene into a single-screw extruder, extrude and form an inner tube;

[0012] S2. Mix ethylene-vinyl alcohol copolymer, basalt fiber, maleic anhydride grafted EPDM and hot melt adhesive evenly, and then transfer them into a single-screw extruder for outer layer auxiliary extrusion and apply them to the surface of the inner tube to form the PE-RT oxygen barrier pipe.

[0013] Further, when the single-screw extruder outer layer auxiliary machine extrudes, the extrusion temperature of the first stage is 180 - 185 °C, the extrusion temperature of the second stage is 185 - 195 °C, the extrusion temperature of the third stage is 195 - 200 °C, the die temperature is 190 - 200 °C, and the rotation speed of the screw is 75 - 100 r / min.

[0014] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0015] The present invention adds basalt fibers to the original oxygen barrier material ethylene-vinyl alcohol copolymer, which will enhance the mechanical properties and oxygen barrier properties of the oxygen barrier pipe. However, since basalt fibers are inorganic materials, it will further reduce the compatibility of the system, making it difficult to improve the mechanical properties and oxygen barrier properties. But adding a common polyethylene grafted polar monomer compatibilizer, such as polyethylene or polypropylene grafted maleic anhydride, although it has a certain promoting effect on the compatibility of the system, it is still difficult to improve the oxygen barrier property and mechanical properties of the oxygen barrier pipe. Adding the compatibilizer maleic anhydride grafted EPDM not only greatly improves the compatibility of the ethylene-vinyl alcohol (EV-OH) oxygen barrier material and PE-RT, making the surface of the oxygen barrier pipe smooth, without crystal point impurities, wrinkling or agglomeration, etc., but also significantly improves the oxygen barrier property and mechanical properties of the oxygen barrier pipe, and the oxygen transmission rate is lower than 0.12 mg / (m 2 ·d). Specific embodiments

[0016] The present invention will be described in detail below with reference to specific embodiments, but these embodiments are not construed as limiting the protection scope of the present invention in any sense.

[0017] The raw materials used in the examples and comparative examples are as follows:

[0018] Ethylene-vinyl alcohol copolymer EVOH: Kuraray Co., Ltd., Japan.

[0019] Heat-resistant polyethylene PE-RT: Lanzhou Petrochemical 3010.

[0020] Maleic anhydride grafted EPDM: Haifei 830M.

[0021] Hot melt adhesive: Shandong Huacheng Gaoke Adhesive Co., Ltd.

[0022] Example 1

[0023] A PE-RT oxygen barrier pipe with excellent performance, including an inner layer and an outer layer. The inner layer is a heat-resistant polyethylene layer, and the outer layer is an oxygen barrier layer;

[0024] The oxygen barrier layer is prepared from the following raw materials in parts by mass:

[0025]

[0026] The preparation method of the above-mentioned excellent-performance PE-RT oxygen-barrier pipe is as follows:

[0027] S1. Add heat-resistant polyethylene into a single-screw extruder, extrude and form an inner tube;

[0028] S2. Mix ethylene-vinyl alcohol copolymer, maleic anhydride-grafted EPDM and hot melt adhesive evenly, then transfer them into a single-screw outer-layer auxiliary extruder for extrusion and apply them to the surface of the inner tube to form the PE-RT oxygen-barrier pipe. The parameters of the single-screw outer-layer auxiliary extruder are as follows: the extrusion temperature of the first stage is 182 °C, the extrusion temperature of the second stage is 190 °C, the extrusion temperature of the third stage is 198 °C, the die temperature is 195 °C, and the rotation speed of the screw is 88 r / min.

[0029] Example 2

[0030] An excellent-performance PE-RT oxygen-barrier pipe includes an inner layer and an outer layer. The inner layer is a heat-resistant polyethylene layer, and the outer layer is an oxygen-barrier layer;

[0031] The oxygen-barrier layer is prepared from the following raw materials in parts by mass:

[0032]

[0033] The preparation method of the above-mentioned excellent-performance PE-RT oxygen-barrier pipe is as follows:

[0034] S1. Add heat-resistant polyethylene into a single-screw extruder, extrude and form an inner tube;

[0035] S2. Mix ethylene-vinyl alcohol copolymer, maleic anhydride-grafted EPDM and hot melt adhesive evenly, then transfer them into a single-screw outer-layer auxiliary extruder for extrusion and apply them to the surface of the inner tube to form the PE-RT oxygen-barrier pipe. The parameters of the single-screw outer-layer auxiliary extruder are as follows: the extrusion temperature of the first stage is 180 °C, the extrusion temperature of the second stage is 195 °C, the extrusion temperature of the third stage is 200 °C, the die temperature is 190 °C, and the rotation speed of the screw is 80 r / min.

[0036] Comparative Example 1

[0037] The difference from Example 1 is that the compatibilizer used in the oxygen-barrier layer formulation is different. In this comparative example, the compatibilizer is maleic anhydride-grafted polyethylene, and the rest remains unchanged.

[0038] Comparative Example 2

[0039] The difference from Example 1 is that the compatibilizer used in the oxygen-barrier layer formulation is different. In this comparative example, the compatibilizer is maleic anhydride-grafted polypropylene, and the rest remains unchanged.

[0040] Comparative Example 3

[0041] The difference from Example 1 is that maleic anhydride grafted EPDM is not used in the oxygen barrier layer formulation.

[0042] Comparative Example 4

[0043] The difference from Example 1 is that maleic anhydride grafted EPDM and basalt fibers are not used in the oxygen barrier layer formulation.

[0044] The oxygen barrier tubes of Example 1 and Comparative Examples 1-4 were subjected to appearance tests and oxygen barrier performance tests. The test results are shown in Table 1 below:

[0045] Table 1 Comparison of the appearance, oxygen barrier performance, and mechanical properties of different oxygen barrier tubes

[0046]

Claims

1. A PE-RT oxygen barrier pipe with excellent performance, characterized in that: It includes an inner layer and an outer layer. The inner layer is a heat-resistant polyethylene layer, and the outer layer is an oxygen barrier layer; The oxygen barrier layer is prepared from the following raw materials in parts by mass: Ethylene-vinyl alcohol copolymer: 100 parts Basalt fiber: 5 - 10 parts Maleic anhydride grafted EPDM: 5 - 18 parts Hot melt adhesive: 1 - 6 parts.

2. The PE-RT oxygen barrier pipe with excellent performance according to claim 1, characterized in that: The hot melt adhesive is a special polyolefin hot melt adhesive.

3. A method for preparing a PE-RT oxygen barrier pipe with excellent performance according to claim 1, characterized in that It includes the following steps: S1. Add the heat-resistant polyethylene into a single-screw extruder, extrude and form an inner tube; S2. Mix the ethylene-vinyl alcohol copolymer, basalt fiber, maleic anhydride grafted EPDM and the hot melt adhesive evenly, then transfer them into a single-screw outer layer auxiliary extruder to extrude and coat them on the surface of the inner tube to form the PE-RT oxygen barrier tube.

4. The method for preparing a PE-RT oxygen barrier pipe with excellent performance according to claim 3, characterized in that: When the single-screw outer layer auxiliary extruder extrudes, the extrusion temperature of the first section is 180 - 185 °C, the extrusion temperature of the second section is 185 - 195 °C, the extrusion temperature of the third section is 195 - 200 °C, the die temperature is 190 - 200 °C, and the rotation speed of the screw is 75 - 100 r / min.

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