Production process of low-temperature-resistant impact-resistant steel wire framework polyethylene pipe

Abstract

The invention relates to the technical field of polyethylene pipes, and discloses a low-temperature-resistant impact-resistant steel wire skeleton polyethylene pipe production process, which comprises: S1, carrying out melt extrusion on inner layer polyethylene to obtain modified polyethylene; the temperature is 180 DEG C, and the screw speed is 30-40 rpm; s2, steel wire skeleton preforming: pre-tightening a steel wire mesh through electromagnetic induction heating (the frequency is 27 MHz, and the power density is 0.5 W / cm < 2 >); and S3, dynamic vulcanization and co-extrusion: dynamically vulcanizing the modified polyethylene and the steel wire skeleton in a double-screw extruder (the dosage of a cross-linking agent DCP is 0.2 part by weight, the temperature is 160 DEG C, and the retention time is 3 minutes), carrying out gradient cooling, and demolding. According to the production process of the low-temperature-resistant and impact-resistant steel wire skeleton polyethylene pipe, the low-temperature-resistant and impact-resistant steel wire skeleton polyethylene pipe has relatively good low-temperature-resistant, impact-resistant, flame-retardant and tensile properties.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene pipes, in particular to a production process of low-temperature-resistant and impact-resistant steel wire skeleton polyethylene pipes. Background Art

[0002] Traditional polyethylene (PE) pipes experience significant performance degradation in low-temperature environments (especially below -40°C). These degradations manifest themselves in the following ways: Low-temperature brittleness: Molecular chain mobility decreases, impact strength is significantly reduced, and brittle fracture is prone to occur. Delamination: The interfacial bonding between the steel wire skeleton and the polyethylene matrix is ​​insufficient, leading to delamination under temperature cycling or mechanical stress. Poor flame retardancy: The limiting oxygen index (LOI) of pure PE is only approximately 17%, making it a flammable material and difficult to meet the requirements of demanding environments (such as chemical and mining industries). Therefore, avoiding these phenomena is key to solving the problem. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the deficiencies in the prior art, the present invention provides a production process for a low-temperature-resistant and impact-resistant steel wire skeleton polyethylene pipe, which has good low-temperature resistance, impact resistance and flame retardancy.

[0005] (2) Technical solution

[0006] To achieve the above object, the present invention provides the following technical solution: a production process for a low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe, characterized in that it comprises the following steps:

[0007] S1. The inner layer of polyethylene is melt-extruded to obtain modified polyethylene; the temperature is 180-200 ° C, the screw speed is 30-40 rpm;

[0008] S2. Steel wire skeleton preforming: by electromagnetic induction heating (frequency 27MHz, power density 0.5W / cm 2 ) Pre-tightened wire mesh;

[0009] S3. Dynamic vulcanization coextrusion: The modified polyethylene and the steel wire skeleton are dynamically vulcanized in a twin-screw extruder (crosslinking agent DCP dosage 0.2 parts by weight, temperature 160°C, residence time 3 minutes), gradient cooling, and demolding.

[0010] Furthermore, the preparation method of the modified polyethylene in S1 is:

[0011] Step 1: Under a nitrogen atmosphere, 7.3-7.7 g of vanillin, 35-38 g of guaiacol, 10.5-10.8 g of DOPO, and 0.2-0.4 g of p-toluenesulfonic acid were added to a reactor, the temperature was raised, the reaction was stirred, and the reaction was cooled and allowed to stand to obtain intermediate 1;

[0012] Step 2: Under a nitrogen atmosphere, 4.71-4.73 g of intermediate 1 and 18.1-18.5 g of epichlorohydrin were added to a reactor, stirred and mixed, and 0.04-0.05 g of tetrabutylammonium bromide was added. The mixture was heated to 80-86° C. and reacted for 3-5 hours. After the reaction, the mixture was cooled to 3-5° C. and 2-4 g of sodium hydroxide solution was slowly added dropwise. The reaction was continued for 10-12 hours. The product was filtered and washed to obtain modified vanillin.

[0013] Step 3: Add 8.26-10.11 g of 2-amino-1,3,4-thiadiazole and 9.14-9.65 g of modified vanillin to 100-120 mL of anhydrous ethanol, react, filter, and wash to obtain thiadiazole-modified vanillin;

[0014] Step 4: 80-90 parts by weight of high-density polyethylene, 5-8 parts by weight of hyperbranched polyamide, 4-6 parts by weight of thiadiazole-modified vanillin, 0.1-0.2 parts by weight of antioxidant 1010, and 1-2 parts by weight of epoxy nano-silica are mixed and melt-blended and granulated through a twin-screw extruder to obtain modified polyethylene.

[0015] Furthermore, the reaction temperature in step 1 is 120-125°C.

[0016] Furthermore, the reaction time in step 1 is 4-6 hours.

[0017] Furthermore, the mass fraction of the sodium hydroxide solution in step 2 is 2.8-3%.

[0018] Furthermore, the reaction temperature in step three is 70-75°C.

[0019] Furthermore, the reaction time in step three is 4-7 hours.

[0020] Furthermore, the blending temperature in step 4 is 160-170°C.

[0021] (3) Beneficial technical effects

[0022] The double-stage treatment of the silane coupling agent of the present invention improves the interfacial shear strength between the steel wire and the polyethylene matrix, and the hyperbranched polyamide and epoxy nano-silica form an interpenetrating network, thereby improving its tensile strength. The thiadiazole-modified vanillin and epoxy nano-silica synergistically improve the flame retardant effect of the pipe, and the phosphorus, nitrogen and sulfur elements in the thiadiazole-modified vanillin constitute a flame retardant system. The polyethylene pipe of the present invention has excellent low-temperature resistance and impact resistance, meeting the requirements of extremely cold environments. The introduction of thiadiazole-modified vanillin and its rigid-flexible synergistic structure (benzene ring + thiadiazole heterocycle) effectively inhibit the propagation of low-temperature microcracks, and the topological entanglement of the hyperbranched polyamide improves the toughness of the matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the reaction formula for modified vanillin. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] DOPO: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0027] Hyperbranched polyamide: branching degree ≥3.

[0028] Pipe specifications: DN200, wall thickness 12mm;

[0029] Low carbon steel wire (diameter 2.0 mm) was treated with a double-stage silane coupling agent (KH550) and a titanate coupling agent (NDZ-201):

[0030] Step 1: Spray 3% KH550 ethanol solution and dry at 80℃;

[0031] Step 2: Impregnation with 2% NDZ-201 silane solution, curing at 120°C. Function: Improve the interfacial bonding strength between the steel wire and the polyethylene matrix. Wire mesh density: 20×20 wires / cm 2 .

[0032] Preparation of epoxy nano-silica: Referring to the literature "Silane coupling agent KH-560 modified nano-silica", a certain amount of nano-silica was weighed and added to 20 mL of toluene. Ultrasonic dispersion was performed at room temperature using a KQ-300E ultrasonic cleaner (300W) for 30 min to obtain a uniform suspension. Silane coupling agent KH-560 was then added thereto and ultrasonic dispersion was continued for 3-4 min. The suspension was transferred to a 100 mL four-necked flask equipped with a reflux condenser and a power-enhanced electric stirrer and stirred in an oil bath at a set temperature for reaction. The slurry after the reaction was centrifuged at room temperature at a speed of 12,000 r / min using a CT15RT desktop high-speed refrigerated centrifuge to obtain epoxy nano-silica.

[0033] Example 1

[0034] S1. The inner layer of polyethylene is melt-extruded to obtain modified polyethylene; the temperature is 180°C and the screw speed is 30-40rpm;

[0035] S2. Steel wire skeleton preforming: by electromagnetic induction heating (frequency 27MHz, power density 0.5W / cm 2 ) Pre-tightened wire mesh;

[0036] S3. Dynamic vulcanization coextrusion: The modified polyethylene and the steel wire skeleton are dynamically vulcanized in a twin-screw extruder (crosslinking agent DCP dosage 0.2 parts by weight, temperature 160°C, residence time 3 minutes), gradient cooling, and demolding.

[0037] The preparation method of the modified polyethylene in S1 is:

[0038] Step 1: Under a nitrogen atmosphere, 7.3 g of vanillin, 35 g of guaiacol, 10.5 g of DOPO, and 0.2 g of p-toluenesulfonic acid were added to a reactor, heated to 120°C, stirred and reacted for 4 h, cooled, and allowed to stand to obtain intermediate 1;

[0039] Step 2: Under a nitrogen atmosphere, 4.71 g of intermediate 1 and 18.1 g of epichlorohydrin were added to a reactor, stirred and mixed, and 0.04 g of tetrabutylammonium bromide was added. The mixture was heated to 80°C and reacted for 3 h. After the reaction, the mixture was cooled to 3°C and 2 g of a 2.8% sodium hydroxide solution was slowly added dropwise. The reaction was continued for 10 h. The product was filtered and washed to obtain modified vanillin.

[0040] Step 3: Add 8.26 g of 2-amino-1,3,4-thiadiazole and 9.14 g of modified vanillin to 100 mL of anhydrous ethanol, react at 70°C for 4 h, filter, and wash to obtain thiadiazole-modified vanillin;

[0041] Step 4: 80 parts by weight of high-density polyethylene, 5 parts by weight of hyperbranched polyamide, 4 parts by weight of thiadiazole-modified vanillin, 0.1 parts by weight of antioxidant 1010, and 1 part by weight of epoxy nano-silica are mixed and melt-blended and granulated through a twin-screw extruder at a blending temperature of 160° C. to obtain modified polyethylene.

[0042] Example 2

[0043] S1. The inner layer of polyethylene was melt extruded to obtain modified polyethylene; the temperature was 200°C and the screw speed was 40 rpm;

[0044] S2. Steel wire skeleton preforming: by electromagnetic induction heating (frequency 27MHz, power density 0.5W / cm 2 ) Pre-tightened wire mesh;

[0045] S3. Dynamic vulcanization coextrusion: The modified polyethylene and the steel wire skeleton are dynamically vulcanized in a twin-screw extruder (crosslinking agent DCP dosage 0.2 parts by weight, temperature 160°C, residence time 3 minutes), gradient cooling, and demolding.

[0046] The preparation method of the modified polyethylene in S1 is:

[0047] Step 1: Under a nitrogen atmosphere, 7.7 g of vanillin, 38 g of guaiacol, 10.8 g of DOPO, and 0.4 g of p-toluenesulfonic acid were added to a reactor, heated to 125°C, stirred and reacted for 6 h, cooled, and allowed to stand to obtain intermediate 1;

[0048] Step 2: Under a nitrogen atmosphere, 4.73 g of intermediate 1 and 18.5 g of epichlorohydrin were added to a reactor, stirred and mixed, and 0.05 g of tetrabutylammonium bromide was added. The mixture was heated to 86° C. and reacted for 5 h. After the reaction, the mixture was cooled to 5° C. and 4 g of a 3% sodium hydroxide solution was slowly added dropwise. The reaction was continued for 12 h. The product was filtered and washed to obtain modified vanillin.

[0049] Step 3: Add 10.11 g of 2-amino-1,3,4-thiadiazole and 9.65 g of modified vanillin to 120 mL of anhydrous ethanol, react at 75°C for 7 h, filter, and wash to obtain thiadiazole-modified vanillin;

[0050] Step 4: 90 parts by weight of high-density polyethylene, 8 parts by weight of hyperbranched polyamide, 6 parts by weight of thiadiazole-modified vanillin, 0.2 parts by weight of antioxidant 1010, and 2 parts by weight of epoxy nano-silica are mixed and melt-blended and granulated through a twin-screw extruder at a blending temperature of 170°C to obtain modified polyethylene.

[0051] Example 3

[0052] S1. The inner layer of polyethylene was melt extruded to obtain modified polyethylene; the temperature was 190°C and the screw speed was 35 rpm;

[0053] S2. Steel wire skeleton preforming: by electromagnetic induction heating (frequency 27MHz, power density 0.5W / cm 2 ) Pre-tightened wire mesh;

[0054] S3. Dynamic vulcanization coextrusion: The modified polyethylene and the steel wire skeleton are dynamically vulcanized in a twin-screw extruder (crosslinking agent DCP dosage 0.2 parts by weight, temperature 160°C, residence time 3 minutes), gradient cooling, and demolding.

[0055] The preparation method of the modified polyethylene in S1 is:

[0056] Step 1: Under a nitrogen atmosphere, 7.5 g of vanillin, 36 g of guaiacol, 10.7 g of DOPO, and 0.3 g of p-toluenesulfonic acid were added to a reactor, heated to 122°C, stirred and reacted for 5 h, cooled, and allowed to stand to obtain intermediate 1;

[0057] Step 2: Under a nitrogen atmosphere, 4.72 g of intermediate 1 and 18.3 g of epichlorohydrin were added to a reactor, stirred and mixed, and 0.04 g of tetrabutylammonium bromide was added. The mixture was heated to 83°C and reacted for 4 h. After the reaction, the mixture was cooled to 4°C and 3 g of a 2.9% sodium hydroxide solution was slowly added dropwise. The reaction was continued for 11 h. The product was filtered and washed to obtain modified vanillin.

[0058] Step 3: Add 9.34 g of 2-amino-1,3,4-thiadiazole and 9.36 g of modified vanillin to 110 mL of anhydrous ethanol, react at 72 °C for 5 h, filter, and wash to obtain thiadiazole-modified vanillin;

[0059] Step 4: 86 parts by weight of high-density polyethylene, 7 parts by weight of hyperbranched polyamide, 5 parts by weight of thiadiazole-modified vanillin, 0.15 parts by weight of antioxidant 1010, and 2 parts by weight of epoxy nano-silica are mixed and melt-blended and granulated through a twin-screw extruder at a blending temperature of 165° C. to obtain modified polyethylene.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 3 is that no thiadiazole-modified vanillin is added.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 3 is that no epoxy nano-silica is added.

[0064] The low-temperature impact resistance test is carried out in accordance with GB / T 5470-2008 "Plastics - Determination of Brittleness Temperature by Impact Method" and ISO 3127 "Plastic Pipes - Drop Weight Impact Test Method".

[0065] Table 1: Low temperature impact resistance test.

[0066]

[0067]

[0068] As can be seen from Table 1, Examples 1-3 of the present invention have better low-temperature impact resistance than Comparative Examples 1-2.

[0069] In accordance with GB / T 2406.2-2009 "Determination of combustion behavior of plastics using the oxygen index method".

[0070] Method: LOI test: Determine the minimum oxygen concentration required to sustain combustion in an oxygen-nitrogen mixture. Vertical combustion: Test the self-extinguishing time of the sample after ignition according to UL94 standard.

[0071] Table 2: Flame retardancy test.

[0072] project Limiting oxygen index (%) Vertical combustion level Example 1 32.6 V-0 Example 2 33.7 V-0 Example 3 34.9 V-0 Comparative Example 1 27.6 V-1 Comparative Example 2 28.4 V-1

[0073] As can be seen from Table 2, Examples 1-3 of the present invention have better flame retardant effects than Comparative Examples 1-2.

[0074] In accordance with GB / T 1040.1-2018 "Determination of tensile properties of plastics".

[0075] Method: Tensile strength: Stretch at 5 mm / min at 23°C until fracture, and record the maximum load.

[0076] Flexural modulus: three-point bending method, span 64 mm, loading rate 2 mm / min.

[0077] Table 3: Tensile strength test.

[0078] project Tensile strength (MPa) Flexural modulus (GPa) Example 1 28.4 1.8 Example 2 30.2 1.9 Example 3 31.5 1.6 Comparative Example 1 22.3 1.4 Comparative Example 2 21.1 1.3

[0079] As can be seen from Table 2, Examples 1-3 of the present invention have better tensile strength than Comparative Examples 1-2.

[0080] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0082] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A production process for low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe, characterized in that: The following steps are involved: S1. The inner layer of polyethylene is melt-extruded to obtain modified polyethylene; the temperature is 180-200 ° C, the screw speed is 30-40 rpm; S2. Steel wire skeleton preforming: by electromagnetic induction heating (frequency 27MHz, power density 0.5W / cm 2 ) Pre-tightened wire mesh; S3. Dynamic vulcanization coextrusion: The modified polyethylene and the steel wire skeleton are dynamically vulcanized in a twin-screw extruder (crosslinking agent DCP dosage 0.2 parts by weight, temperature 160°C, residence time 3 minutes), gradient cooling, and demolding.

2. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 1, characterized in that: The preparation method of the modified polyethylene in S1 is: Step 1: Under a nitrogen atmosphere, 7.3-7.7 g of vanillin, 35-38 g of guaiacol, 10.5-10.8 g of DOPO, and 0.2-0.4 g of p-toluenesulfonic acid were added to a reactor, the temperature was raised, the reaction was stirred, and the reaction was cooled and allowed to stand to obtain intermediate 1; Step 2: Under a nitrogen atmosphere, 4.71-4.73 g of intermediate 1 and 18.1-18.5 g of epichlorohydrin were added to a reactor, stirred and mixed, and 0.04-0.05 g of tetrabutylammonium bromide was added. The mixture was heated to 80-86° C. and reacted for 3-5 hours. After the reaction, the mixture was cooled to 3-5° C. and 2-4 g of sodium hydroxide solution was slowly added dropwise. The reaction was continued for 10-12 hours. The product was filtered and washed to obtain modified vanillin. Step 3: Add 8.26-10.11 g of 2-amino-1,3,4-thiadiazole and 9.14-9.65 g of modified vanillin to 100-120 mL of anhydrous ethanol, react, filter, and wash to obtain thiadiazole-modified vanillin; Step 4: 80-90 parts by weight of high-density polyethylene, 5-8 parts by weight of hyperbranched polyamide, 4-6 parts by weight of thiadiazole-modified vanillin, 0.1-0.2 parts by weight of antioxidant 1010, and 1-2 parts by weight of epoxy nano-silica are mixed and melt-blended and granulated through a twin-screw extruder to obtain modified polyethylene.

3. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The reaction temperature in step 1 is 120-125°C.

4. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The reaction time in step 1 is 4-6 hours.

5. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The mass fraction of the sodium hydroxide solution in step 2 is 2.8-3%.

6. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The reaction temperature in step 3 is 70-75°C.

7. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The reaction time in step 3 is 4-7h.

8. The production process of the low-temperature resistant and impact-resistant steel wire skeleton polyethylene pipe according to claim 2, characterized in that: The blending temperature in step 4 is 160-170°C.

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