Steel-plastic composite pipe capable of improving cold and hot stress resistance of bonding interface

Abstract

The invention discloses a steel-plastic composite pipe capable of improving cold and hot stress resistance of a bonding interface, the steel-plastic composite pipe comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from inside to outside, and the inner plastic layer and the outer plastic layer are formed by extrusion molding of 100 parts by mass of polyolefin and 2-5 parts by mass of EVA as raw materials. The hot melt adhesive layer is prepared from the specially-made hot melt adhesive as a raw material. The inner pipe of the steel-plastic composite pipe modifies the materials of the inner plastic layer and the outer plastic layer and is matched with the specially designed hot melt adhesive, so that the bonding quality between the inner plastic layer and the steel pipe layer as well as between the outer plastic layer and the steel pipe layer is improved, the cold and hot stress resistance of the bonding interface of the steel-plastic composite pipe is improved, the steel-plastic composite pipe is not prone to cracking, falling off and the like, and the service life of the steel-plastic composite pipe is prolonged. And the service life of the steel-plastic composite pipe is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of steel-plastic composite pipe production, and in particular relates to a steel-plastic composite pipe with improved cold and hot stress resistance performance of a bonding interface. Background Art

[0002] With the development of the national economy and the improvement of people's living standards, people have higher and higher requirements on the functions and quality of pipelines used in life and production activities. They not only require safe and reliable operation of the pipeline network, convenient and quick installation and maintenance, but also require excellent pipeline performance.

[0003] Steel-plastic composite pipe (is a new type of metal and plastic composite pipe, which adopts a composite structure with a reinforced welded steel pipe in the middle and plastic layers inside and outside. It overcomes the defects of the steel pipe itself, which is easy to rust, pollute, bulky, and short service life, and the plastic pipe itself, which has low strength, large expansion, and easy deformation. It has the advantages of high strength of steel pipe, easy detection of buried pipe, corrosion resistance of plastic pipe, and smooth pipe wall. It has a large application space and performance advantages in medium and low pressure water supply pipelines.

[0004] The steel-plastic composite pipe is composed of five layers, from inside to outside: inner plastic layer, hot melt adhesive layer, steel pipe layer, hot melt adhesive layer and outer plastic layer. If the inner plastic layer and / or outer plastic layer are not firmly bonded to the steel pipe layer, the cold and hot stress resistance of the steel-plastic composite pipe bonding interface will decrease, and the hot melt adhesive layer will easily crack and fall off, thereby reducing the overall performance and service life of the steel-plastic pipe. Summary of the invention

[0005] Based on the above-mentioned prior art, the present invention provides a steel-plastic composite pipe with improved cold and heat stress resistance of the bonding interface. The inner pipe of the steel-plastic composite pipe improves the bonding quality between the inner plastic layer and the outer plastic layer and the steel pipe layer by modifying the materials of the inner plastic layer and the outer plastic layer, and cooperating with a specially designed hot-melt adhesive, thereby improving the cold and heat stress resistance of the bonding interface of the steel-plastic composite pipe, making the steel-plastic composite pipe not easy to crack, fall off, etc., thereby increasing the service life of the steel-plastic composite pipe.

[0006] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0007] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0008]

[0009]

[0010] Furthermore, the PP-based hot melt adhesive is selected from at least one of copolymer polypropylene-based hot melt adhesive, homopolymer polypropylene-based hot melt adhesive, and random copolymer polypropylene-based hot melt adhesive.

[0011] Furthermore, the maleic anhydride grafted polypropylene is selected from at least one of maleic anhydride grafted copolymer polypropylene, maleic anhydride grafted homopolypropylene, and maleic anhydride grafted random copolymer polypropylene.

[0012] Furthermore, the tackifying resin is selected from at least one of rosin resin, C5 / C9 petroleum resin and terpene resin.

[0013] Furthermore, the lubricant is selected from at least one of PE wax, diffusion oil, zinc stearate and pentaerythritol stearate.

[0014] Furthermore, the antioxidant is at least one of antioxidant 1010, antioxidant 168, antioxidant 626 and antioxidant 2246.

[0015] A method for preparing a hot melt adhesive for preparing a steel-plastic composite pipe comprises the following steps:

[0016] S1, mixing PP-based hot melt adhesive, nano-silicon dioxide, graphene, maleic anhydride grafted polypropylene, tackifying resin, lubricant and antioxidant to obtain a mixed material;

[0017] S2, adding the mixed material into a high-speed twin-screw extruder, setting the barrel temperature of the twin-screw extruder to 150-200° C., extruding and granulating, and obtaining the hot melt adhesive for preparing the steel-plastic composite pipe.

[0018] A steel-plastic composite pipe with improved cold and hot stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both formed by extrusion using 100 parts by mass of polyolefin and 2-5 parts by mass of EVA as raw materials, and the hot melt adhesive layer is prepared using hot melt adhesive used for preparing steel-plastic composite pipes as raw material.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0020] 1. The present invention modifies the common polyolefin EVA used for the inner plastic layer and the outer plastic layer, and bonds the inner plastic layer and the outer plastic layer to the steel pipe layer with a special hot melt adhesive of a special formula. The special hot melt adhesive is based on the PP-based hot melt adhesive, and nano-silicon dioxide and graphene are added. Nano-silicon dioxide improves the heat resistance of the hot melt adhesive, and graphene has good thermal conductivity. EVA, which is easy to heat at high frequency, makes the inner plastic layer and the outer plastic layer heat up faster, and works together with the thermal conductivity of graphene to improve the bonding quality between the inner plastic layer and the outer plastic layer and the steel pipe layer, thereby improving the cold and heat stress resistance of the bonding interface of the steel-plastic composite pressure pipe.

[0021] 2. The present invention improves the pipe peeling strength of the pipe and the bonding quality between the inner plastic layer and the outer plastic layer and the steel pipe layer by using the modified inner plastic layer and the outer plastic layer in combination with the special hot melt adhesive, thereby improving the yield rate of the pipe and shortening the time for the hot melt adhesive layer to reach a stable state, so that the bonding quality meets the standard as soon as possible and shortens the pipe molding cycle. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to specific embodiments.

[0023] Example 1

[0024] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0025]

[0026] The preparation method of the hot melt adhesive for preparing the steel-plastic composite pipe is as follows:

[0027] 1. Add nano-silicon dioxide, graphene, tackifying resin, PE wax, diffusion oil, antioxidant 1010 and antioxidant 168 into a small mixer and mix them evenly at high speed;

[0028] 2. Add the mixed material obtained in step 1, hot melt adhesive ADMER QF551 and maleic anhydride grafted homopolymerized polypropylene into a large mixer and mix them evenly at high speed;

[0029] 3. Transfer the mixed material obtained in step 2 to the hopper of a twin-screw extruder, and granulate it through a twin-screw extruder. Set the parameters of the twin-screw extruder as follows: 165°C in zone 1, 175°C in zone 2, 185°C in zone 3, 195°C in zone 4, and 185°C in zone 5 to obtain the hot melt adhesive for preparing the steel-plastic composite pipe.

[0030] A steel-plastic composite pipe with improved cold and heat stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both formed by extrusion using 100 parts by mass of polypropylene and 3.5 parts by mass of EVA as raw materials, and the hot melt adhesive layer is prepared using the hot melt adhesive used for preparing the steel-plastic composite pipe of this embodiment as raw material.

[0031] The preparation method of the material for the inner plastic layer or the outer plastic layer is as follows:

[0032] Add polypropylene and EVA into a mixer and mix at a high speed of 350 rpm for 20 minutes to obtain a mixed material. Then add the mixed material into a twin-screw extruder for granulation. The parameters of the twin-screw extruder are set as follows: barrel zone 175°C, zone 2 185°C, zone 3 195°C, zone 4 200°C, zone 5 195°C to obtain the inner plastic layer or outer plastic layer material.

[0033] The preparation method of the steel-plastic composite pipe is prepared according to the method disclosed in the Chinese patent application "A new type of PSP steel-plastic composite pipe production method and device" (200610018959.3).

[0034] Example 2

[0035] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0036]

[0037] The preparation method of the hot melt adhesive used to prepare the steel-plastic composite pipe in this embodiment is the same as that in Example 1.

[0038] A steel-plastic composite pipe with improved cold and heat stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both made of 100 parts by mass of polypropylene and 2 parts by mass of EVA as raw materials through extrusion molding, and the hot melt adhesive layer is prepared using the hot melt adhesive used for preparing the steel-plastic composite pipe of this embodiment as raw material.

[0039] The steel-plastic composite pipe with improved cold and heat stress resistance of the bonding interface in this embodiment is the same as that in Embodiment 1.

[0040] Example 3

[0041] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0042]

[0043] The preparation method of the masterbatch with super thermal conductivity and anti-scaling function in this embodiment is the same as that in Example 1.

[0044] A steel-plastic composite pipe with improved cold and hot stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both made of 100 parts by mass of polypropylene and 5 parts by mass of EVA as raw materials through extrusion molding, and the hot melt adhesive layer is made of the hot melt adhesive used for preparing the steel-plastic composite pipe in the embodiment as raw material.

[0045] The steel-plastic composite pipe with improved cold and heat stress resistance of the bonding interface in this embodiment is the same as that in Embodiment 1.

[0046] Comparative Example 1

[0047] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0048]

[0049] The preparation method of the hot melt adhesive used to prepare the steel-plastic composite pipe in this comparative example is the same as that in Example 1.

[0050] A steel-plastic composite pipe with improved cold and hot stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both made of polypropylene as a raw material by extrusion molding, and the hot melt adhesive layer is made of the hot melt adhesive used for preparing the steel-plastic composite pipe in this comparative example as a raw material.

[0051] Comparative Example 2

[0052] A hot melt adhesive for preparing a steel-plastic composite pipe is prepared from the following raw materials in parts by weight:

[0053]

[0054] The preparation method of the hot melt adhesive used to prepare the steel-plastic composite pipe in this comparative example is the same as that in Example 1.

[0055] A steel-plastic composite pipe with improved cold and hot stress resistance of the bonding interface comprises an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both made of polypropylene as a raw material through extrusion molding, and the hot melt adhesive layer is made of the hot melt adhesive used for preparing the steel-plastic composite pipe in this comparative example as a raw material.

[0056] The steel-plastic composite pipes prepared in Examples 1-3 and Comparative Examples 1-2 were tested for burst strength, bonding performance, weld strength, oxidation induction time and melt mass flow rate change rate according to the national standard GB / T 43852-2024, and a flat test was performed. The results are shown in the following table:

[0057]

[0058]

Claims

1. A hot melt adhesive for preparing steel-plastic composite pipes, characterized in that It is prepared from the following raw materials in parts by weight:

2. The hot melt adhesive for preparing steel-plastic composite pipe according to claim 1, characterized in that: The PP-based hot melt adhesive is selected from at least one of copolymer polypropylene-based hot melt adhesive, homopolymer polypropylene-based hot melt adhesive and random copolymer polypropylene-based hot melt adhesive.

3. The hot melt adhesive for preparing steel-plastic composite pipe according to claim 1, characterized in that: The maleic anhydride grafted polypropylene is selected from at least one of maleic anhydride grafted copolymer polypropylene, maleic anhydride grafted homopolymer polypropylene and maleic anhydride grafted random copolymer polypropylene.

4. The hot melt adhesive for preparing steel-plastic composite pipe according to claim 1, characterized in that: The tackifying resin is selected from at least one of rosin resin, C5 / C9 petroleum resin and terpene resin.

5. The hot melt adhesive for preparing steel-plastic composite pipe according to claim 1, characterized in that: The lubricant is selected from at least one of PE wax, diffusion oil, zinc stearate and pentaerythritol stearate.

6. The masterbatch with super thermal conductivity and anti-scaling function according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 168, antioxidant 626 and antioxidant 2246.

7. A method for preparing a hot melt adhesive for preparing a steel-plastic composite pipe according to claim 1, characterized in that The steps include: S1, mixing PP-based hot melt adhesive, nano-silicon dioxide, graphene, maleic anhydride grafted polypropylene, tackifying resin, lubricant and antioxidant to obtain a mixed material; S2, adding the mixed material into a twin-screw extruder, setting the barrel temperature of the twin-screw extruder to 150-200° C., extruding and granulating, and obtaining the hot melt adhesive for preparing the steel-plastic composite pipe.

8. A steel-plastic composite pipe with improved cold and hot stress resistance at the bonding interface, characterized in that: It includes an inner plastic layer, a hot melt adhesive layer, a steel pipe layer, a hot melt adhesive layer and an outer plastic layer which are sequentially distributed from the inside to the outside, wherein the inner plastic layer and the outer plastic layer are both formed by extrusion using 100 parts by mass of polyolefin and 2-5 parts by mass of EVA as raw materials, and the hot melt adhesive layer is prepared using the hot melt adhesive for preparing the steel-plastic composite pipe as described in claim 1 as raw material.

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