A PVC pipe composition and a preparation method of a PVC pipe

Abstract

The present invention relates to the technical field of PVC pipe production and processing, and specifically discloses a PVC pipe composition and a preparation method of a PVC pipe. The present invention uses a compound of PVC resin and PE resin to reduce the problem of PVC decomposition caused by high temperature during the processing. At the same time, the PE resin also has good flexibility. By compounding the PVC resin and the PE resin, the mechanical properties of the PVC pipe can be improved. In the composite modified attapulgite provided by the present invention, 4-carboxyphenylboronic acid forms a B-O-B cross-linked network structure at high temperature, which can cooperate with composite metal oxides (zinc oxide, manganese oxide) to improve the thermal stability and density of the carbon layer, thereby improving the flame retardant performance of the PVC pipe. At the same time, acrylate copolymerizes with 2-butene-1,4-diol to form a flexible alkyl long-chain structure, which undergoes reversible deformation under external force, further improving the mechanical properties of the PVC pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of PVC pipe production and processing, and specifically relates to a PVC pipe composition and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) pipes are mainly made of polyvinyl chloride resin, and have the advantages of light weight, high mechanical strength, chemical corrosion resistance, good electrical insulation, etc. At the same time, they have the characteristics of long service life and low cost, so they are widely used in the fields of construction, electricity and communication. However, the current production process with pure PVC resin as the main raw material has obvious shortcomings. Although it is improved by adding auxiliary materials and plasticizers, the pipes produced still generally have the problem of insufficient plasticity, and it is difficult to meet the requirements of material flexibility in most production scenarios.

[0003] In the current production process, a large amount of additives such as plasticizers and stabilizers need to be added, and these components will significantly weaken the flame retardant performance of polyvinyl chloride materials. With the improvement of modern building safety standards, especially in environments with high fire risks, the flame retardancy of traditional PVC pipes has gradually become difficult to meet the market demand.

[0004] Although pure PVC resin as the main raw material can ensure basic performance, the high raw material cost prompts enterprises to seek alternative solutions, and simple additive blending cannot completely solve the problems of poor mechanical properties and insufficient flame retardancy. How to break through the existing limitations through material modification or process innovation has become a key topic for promoting the industrial upgrading of PVC pipes.

[0005] Chinese Patent Document CN202110397226.X discloses a PVC composition, a preparation method and an application thereof. The composition includes the following components calculated by weight: 80-100 parts of polyvinyl chloride resin; 40-80 parts of calcium carbonate; 0.5-1.0 part of high melting point polyethylene wax; 0.5-1.0 part of paraffin wax; 2-8 parts of toughening agent; 2-4 parts of organic tin stabilizer; the prepared composition has the characteristics of low friction coefficient, good mechanical properties, acid and alkali resistance and corrosion resistance, but the flame retardant performance still needs to be further improved. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a PVC pipe composition and a preparation method thereof.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A PVC pipe composition, by weight, comprises raw materials of the following components: 60 - 80 parts of PVC resin, 20 - 30 parts of PE resin, 15 - 25 parts of composite modified attapulgite, 10 - 20 parts of compatibilizer, 4 - 6 parts of heat stabilizer, 5 - 10 parts of lubricant, 1 - 3 parts of antioxidant, and 1 - 2 parts of ultraviolet absorber.

[0009] In the technical solution disclosed in the present invention, the preparation method of the composite modified attapulgite is as follows:

[0010] S1. Dissolve zinc nitrate and manganese nitrate in deionized water, then add attapulgite thereto, ultrasonically disperse evenly, and then add oxalic acid solution thereto. After stirring, filtering, washing, drying, and calcining, attapulgite composite is obtained;

[0011] S2. Disperse the attapulgite composite in an ethanol aqueous solution, then add vinyltriethoxysilane thereto, stir and react, and then after filtering, washing, and drying, a double - bond modified attapulgite composite is obtained;

[0012] S3. Disperse the double - bond modified attapulgite composite in an organic solvent, then add acrylate, 2 - butene - 1,4 - diol, and an initiator thereto, heat and stir the reaction under a nitrogen atmosphere. After the reaction is completed, add 4 - carboxylphenylboronic acid and a catalyst thereto, continue the reaction. After the reaction is completed, filter, wash, and dry to obtain the composite modified attapulgite.

[0013] Specifically, in step S1, the mass ratio of zinc nitrate, manganese nitrate, attapulgite, and oxalic acid solution is 2 - 4:2 - 4:10 - 15:20 - 30.

[0014] More specifically, the concentration of the oxalic acid solution is 0.5 - 2 mol / L. For example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0015] Specifically, in step S1, the stirring temperature is 50 - 70 °C. For example, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C can be selected; the stirring time is 4 - 8 h. For example, 4 h, 5 h, 6 h, 7 h, 8 h can be selected; but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0016] Specifically, in step S1, the calcining temperature is 800 - 1000 °C. For example, 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C can be selected; the calcining time is 2 - 4 h. For example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0017] Specifically, in step S2, the mass ratio of the attapulgite composite to vinyltriethoxysilane is 10-15:1-3. For example, it can be 10:1, 10:2, 10:3, 12:1, 12:2, 12:3, 15:1, 15:2, 15:3, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0018] Specifically, in step S3, the mass ratio of the double-bond modified attapulgite composite, acrylate, 2-butene-1,4-diol, initiator, 4-carboxyphenylboronic acid, and catalyst is 10-20:3-6:3-6:1-2:3-5:1-2.

[0019] More specifically, the acrylate has ≥10 carbon atoms. For example, lauryl acrylate, lauryl methacrylate, or octadecyl acrylate can be selected.

[0020] More specifically, the initiator is selected from benzoyl peroxide or azobisisobutyronitrile.

[0021] More specifically, the catalyst is selected from 4-dimethylaminopyridine.

[0022] In the technical solution disclosed in the present invention, the compatibilizer is selected from ethylene vinyl acetate graft maleic anhydride or polyethylene graft maleic anhydride.

[0023] In the technical solution disclosed in the present invention, the heat stabilizer is selected from calcium zinc heat stabilizer or organotin heat stabilizer.

[0024] In the technical solution disclosed in the present invention, the lubricant is selected from one or more of calcium stearate, polyethylene wax, stearic acid, and monoglyceryl stearate.

[0025] In the technical solution disclosed in the present invention, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, and antioxidant DLTDP.

[0026] In the technical solution disclosed in the present invention, the ultraviolet absorber is selected from one or more of titanium dioxide, UV328, UV327, and UV326.

[0027] The present invention also provides a method for preparing a PVC pipe, which includes the following steps: adding the raw materials of the above PVC pipe composition into a high-speed mixer according to the formula ratio and mixing evenly, then extruding and pelletizing in a twin-screw extruder, and then cooling and shaping to obtain the PVC pipe.

[0028] More specifically, the mixing speed in the high-speed mixer is 1000-1500 r / min, the mixing time is 5-15 min, and the mixing temperature is 100-120 °C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention uses PVC resin and PE resin for compounding. The addition of PE resin can significantly improve the melt fluidity of PVC resin, reduce the processing temperature requirement, and reduce the problem of PVC decomposition caused by high temperature during processing. At the same time, PE resin also has good flexibility. By compounding PVC resin and PE resin, the mechanical properties of PVC pipes can be improved.

[0031] (2) In the present invention, zinc oxalate and manganese oxalate are first loaded on the surface of attapulgite, and then calcined to form a composite metal oxide of zinc oxide and manganese oxide on the surface of attapulgite; then double bonds are introduced on the surface of the attapulgite composite, and through the addition reaction between the double bonds, acrylate and 2-butene-1,4-diol are grafted on the surface of the attapulgite composite. Finally, under the action of a catalyst, 4-carboxyphenylboronic acid and 2-butene-1,4-diol undergo an esterification reaction to obtain a composite modified attapulgite; the 4-carboxyphenylboronic acid in the composite modified attapulgite provided by the present invention forms a B-O-B cross-linked network structure at high temperature, which can react with the composite metal oxide (zinc oxide, manganese oxide) to form a borate glass layer. This composite carbon layer has higher thermal stability and density, can effectively block oxygen and heat, and the 4-carboxyphenylboronic acid and the composite metal oxide act synergistically to jointly improve the flame retardant performance of PVC pipes.

[0032] (3) In the composite modified attapulgite provided by the present invention, acrylate and 2-butene-1,4-diol copolymerize to form a flexible alkyl long-chain structure, which significantly reduces the rigidity of the PVC resin material and improves the impact resistance of the material; at the same time, the flexibility of the alkyl long-chain enables the PVC molecular chain to undergo reversible deformation under the action of external force, and delays fracture through chain segment slip and microcrack passivation, further improving the mechanical properties of PVC pipes; in addition, the hydrophobic alkyl long-chain structure and the benzene ring structure in 4-carboxyphenylboronic acid show good aging resistance in a humid and hot environment, enabling PVC pipes to also show good stability under humid and hot conditions, being able to resist the erosion of the humid and hot environment and delaying the aging process. Detailed implementation manners

[0033] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0034] It should be noted that unless otherwise specified, the chemical reagents involved in the present invention are all purchased through commercial channels.

[0035] In the embodiments of the present invention, the PVC resin used has the grade of SG-5 and is purchased from Zibo Anhao Chemical Co., Ltd.; the PE resin has the grade of PE6004 and the CAS number: 25135-73-3; the attapulgite has a mesh number of 200; the ethylene vinyl acetate grafted maleic anhydride has the grade: Bynel 3810; the polyethylene grafted maleic anhydride has the grade: DuPont 41E710; the calcium zinc heat stabilizer has the CAS number: 1592-23-0.

[0036] Example 1

[0037] A method for preparing a PVC pipe comprises the following steps:

[0038] Add 60 parts of PVC resin, 20 parts of PE resin, 15 parts of composite modified attapulgite, 10 parts of compatibilizer ethylene vinyl acetate grafted maleic anhydride, 4 parts of calcium zinc heat stabilizer, 5 parts of stearic acid, 1 part of antioxidant 168 and 1 part of ultraviolet absorber UV327 into a high-speed mixer and mix evenly. The mixing speed in the high-speed mixer is 1000 r / min, the mixing time is 10 min, and the mixing temperature is 120 °C. Then, extrude and pelletize in a twin-screw extruder. Set the temperature of the first zone of the extruder to 195 °C, the second zone to 190 °C, the third zone to 180 °C, the fourth zone to 175 °C, the fifth zone to 170 °C, and the head temperature to 165 °C. Then, cool and shape to obtain the PVC pipe.

[0039] Among them, the preparation method of the composite modified attapulgite is as follows:

[0040] S1. Dissolve 2 g of zinc nitrate and 2 g of manganese nitrate in 150 mL of deionized water, then add 10 g of attapulgite thereto, ultrasonically disperse evenly, then add 20 g of 1 mol / L oxalic acid solution thereto, stir at 60 °C for 6 h, filter, wash, dry, and calcine at 900 °C for 3 h to obtain an attapulgite composite;

[0041] S2. Disperse 10 g of the attapulgite composite in 150 mL of 80 wt% ethanol aqueous solution, then add 1 g of vinyltriethoxysilane thereto, stir at room temperature for 2 h, then filter, wash, dry to obtain a double-bond modified attapulgite composite;

[0042] S3. Disperse 10 g of the double-bond modified attapulgite composite in 150 mL of organic solvent DMF, then add 3 g of lauryl acrylate, 3 g of 2-butene-1,4-diol and 1 g of initiator azobisisobutyronitrile thereto, heat and stir for reaction at 75 °C under a nitrogen atmosphere for 3 h. After the reaction is completed, add 3 g of 4-carboxyphenylboronic acid and 1 g of catalyst 4-dimethylaminopyridine thereto, continue the reaction at 75 °C for 2 h. After the reaction is completed, filter, wash, dry to obtain the composite modified attapulgite.

[0043] Example 2

[0044] A preparation method of PVC pipes comprises the following steps:

[0045] Add 80 parts of PVC resin, 30 parts of PE resin, 25 parts of composite modified attapulgite, 20 parts of compatibilizer polyethylene grafted maleic anhydride, 6 parts of calcium zinc heat stabilizer, 4 parts of stearic acid, 4 parts of polyethylene wax, 2 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 into a high-speed mixer and mix evenly. The mixing speed in the high-speed mixer is 1000 r / min, the mixing time is 10 min, and the mixing temperature is 120 °C. Then, extrude and pelletize in a twin-screw extruder. Set the temperature of the first zone of the extruder to 195 °C, the second zone to 190 °C, the third zone to 180 °C, the fourth zone to 175 °C, the fifth zone to 170 °C, and the head temperature to 165 °C. Then, cool and shape to obtain PVC pipes.

[0046] Among them, the preparation method of the composite modified attapulgite is as follows:

[0047] S1. Dissolve 4 g of zinc nitrate and 2 g of manganese nitrate in 150 mL of deionized water, then add 12 g of attapulgite thereto, disperse evenly by ultrasonic wave, then add 20 g of 1 mol / L oxalic acid solution thereto, stir at 60 °C for 6 h, filter, wash, dry, and calcine at 900 °C for 3 h to obtain attapulgite composite;

[0048] S2. Disperse 12 g of attapulgite composite in 150 mL of 80 wt% ethanol aqueous solution, then add 2 g of vinyltriethoxysilane thereto, stir at room temperature for 2 h, then filter, wash, dry to obtain double-bond modified attapulgite composite;

[0049] S3. Disperse 15 g of double-bond modified attapulgite composite in 150 mL of organic solvent DMF, then add 4 g of lauryl acrylate, 4 g of 2-butene-1,4-diol and 1.5 g of initiator azobisisobutyronitrile thereto, heat and stir for reaction at 75 °C under nitrogen atmosphere for 3 h. After the reaction is completed, add 4 g of 4-carboxyphenylboronic acid and 1.5 g of catalyst 4-dimethylaminopyridine thereto, continue to react at 75 °C for 2 h. After the reaction is completed, filter, wash, dry to obtain the composite modified attapulgite.

[0050] Example 3

[0051] A preparation method of PVC pipes comprises the following steps:

[0052] 65 parts of PVC resin, 25 parts of PE resin, 20 parts of compound modified attapulgite clay, 15 parts of compatibilizer polyethylene grafted maleic anhydride, 5 parts of calcium zinc heat stabilizer, 6 parts of monoglyceride stearate, 4 parts of polyethylene wax, 3 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 were added to a high-speed mixer and mixed evenly. The mixing speed in the high-speed mixer was 1000 r / min, the mixing time was 10 min, and the mixing temperature was 120 °C. Subsequently, it was extruded and granulated in a twin-screw extruder. The temperature of the first zone of the extruder was set at 195 °C, the second zone at 190 °C, the third zone at 180 °C, the fourth zone at 175 °C, the fifth zone at 170 °C, and the head temperature was set at 165 °C. After cooling and shaping, PVC pipes were obtained.

[0053] Among them, the preparation method of the compound modified attapulgite clay is as follows:

[0054] S1. 2 g of zinc nitrate and 4 g of manganese nitrate were dissolved in 150 mL of deionized water, then 15 g of attapulgite clay was added thereto, ultrasonically dispersed evenly, and then 20 g of 1 mol / L oxalic acid solution was added thereto. It was stirred at 60 °C for 6 h, filtered, washed, dried, and calcined at 900 °C for 3 h to obtain attapulgite clay composite.

[0055] S2. 15 g of attapulgite clay composite was dispersed in 150 mL of 80 wt% ethanol aqueous solution, then 3 g of vinyltriethoxysilane was added thereto, stirred at room temperature for 2 h, and then filtered, washed, and dried to obtain double-bond modified attapulgite clay composite.

[0056] S3. 20 g of double-bond modified attapulgite clay composite was dispersed in 150 mL of organic solvent DMF, then 6 g of lauryl acrylate, 6 g of 2-butene-1,4-diol and 2 g of initiator azobisisobutyronitrile were added thereto. It was heated and stirred at 75 °C in a nitrogen atmosphere for 3 h. After the reaction was completed, 5 g of 4-carboxyphenylboronic acid and 2 g of catalyst 4-dimethylaminopyridine were added thereto, and the reaction was continued at 75 °C for 2 h. After the reaction was completed, it was filtered, washed, and dried to obtain the compound modified attapulgite clay.

[0057] Comparative Example 1

[0058] A preparation method of PVC pipes includes the following steps:

[0059] 65 parts of PVC resin, 25 parts of PE resin, 20 parts of attapulgite, 15 parts of compatibilizer polyethylene grafted maleic anhydride, 5 parts of calcium-zinc heat stabilizer, 6 parts of monoglyceride stearate, 4 parts of polyethylene wax, 3 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 were added to a high-speed mixer and mixed evenly. The mixing speed in the high-speed mixer was 1000 r / min, the mixing time was 10 min, and the mixing temperature was 120 °C. Subsequently, it was extruded and granulated in a twin-screw extruder. The temperature of the first zone of the extruder was set at 195 °C, the second zone at 190 °C, the third zone at 180 °C, the fourth zone at 175 °C, the fifth zone at 170 °C, and the head temperature was set at 165 °C. After cooling and shaping, PVC pipes were obtained.

[0060] Compared with Example 3, in Comparative Example 1, the attapulgite was not modified.

[0061] Comparative Example 2

[0062] A preparation method of PVC pipes includes the following steps:

[0063] 65 parts of PVC resin, 25 parts of PE resin, 20 parts of composite modified attapulgite, 15 parts of compatibilizer polyethylene grafted maleic anhydride, 5 parts of calcium-zinc heat stabilizer, 6 parts of monoglyceride stearate, 4 parts of polyethylene wax, 3 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 were added to a high-speed mixer and mixed evenly. The mixing speed in the high-speed mixer was 1000 r / min, the mixing time was 10 min, and the mixing temperature was 120 °C. Subsequently, it was extruded and granulated in a twin-screw extruder. The temperature of the first zone of the extruder was set at 195 °C, the second zone at 190 °C, the third zone at 180 °C, the fourth zone at 175 °C, the fifth zone at 170 °C, and the head temperature was set at 165 °C. After cooling and shaping, PVC pipes were obtained.

[0064] Among them, the preparation method of the composite modified attapulgite is as follows:

[0065] S1. 15 g of attapulgite was dispersed in 150 mL of 80 wt% ethanol aqueous solution, then 3 g of vinyltriethoxysilane was added thereto, and it was stirred at room temperature for 2 h. Subsequently, it was filtered, washed, and dried to obtain double-bond modified attapulgite;

[0066] S2. 20 g of double-bond modified attapulgite was dispersed in 150 mL of organic solvent DMF, then 6 g of lauryl acrylate, 6 g of 2-butene-1,4-diol and 2 g of initiator azobisisobutyronitrile were added thereto, and it was heated and stirred at 75 °C under a nitrogen atmosphere for 3 h. After the reaction was completed, 5 g of 4-carboxyphenylboronic acid and 2 g of catalyst 4-dimethylaminopyridine were added thereto, and the reaction was continued at 75 °C for 2 h. After the reaction was completed, it was filtered, washed, and dried to obtain the composite modified attapulgite.

[0067] In Comparative Example 2 compared with Example 3, zinc oxide and manganese oxide were not loaded on attapulgite.

[0068] Comparative Example 3

[0069] A method for preparing a PVC pipe comprises the following steps:

[0070] 65 parts of PVC resin, 25 parts of PE resin, 20 parts of compound modified attapulgite, 15 parts of compatibilizer polyethylene grafted maleic anhydride, 5 parts of calcium-zinc heat stabilizer, 6 parts of monoglyceryl stearate, 4 parts of polyethylene wax, 3 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 are added to a high-speed mixer and mixed evenly. The mixing speed in the high-speed mixer is 1000 r / min, the mixing time is 10 min, and the mixing temperature is 120 °C. Subsequently, it is extruded and granulated in a twin-screw extruder. The temperature of the first zone of the extruder is set at 195 °C, the second zone at 190 °C, the third zone at 180 °C, the fourth zone at 175 °C, the fifth zone at 170 °C, and the head temperature is set at 165 °C. Then, it is cooled and shaped to obtain the PVC pipe.

[0071] Among them, the preparation method of the compound modified attapulgite is as follows:

[0072] S1. 2 g of zinc nitrate and 4 g of manganese nitrate are dissolved in 150 mL of deionized water, then 15 g of attapulgite is added thereto, ultrasonically dispersed evenly, and then 20 g of 1 mol / L oxalic acid solution is added thereto. It is stirred at 60 °C for 6 h, filtered, washed, dried, and calcined at 900 °C for 3 h to obtain an attapulgite composite;

[0073] S2. 15 g of the attapulgite composite is dispersed in 150 mL of 80 wt% ethanol aqueous solution, then 3 g of vinyltriethoxysilane is added thereto, stirred at room temperature for 2 h, and then filtered, washed, and dried to obtain a double-bond modified attapulgite composite;

[0074] S3. 20 g of the double-bond modified attapulgite composite is dispersed in 150 mL of organic solvent DMF, then 6 g of 2-butene-1,4-diol and 2 g of initiator azobisisobutyronitrile are added thereto. It is heated and stirred at 75 °C for 3 h under a nitrogen atmosphere. After the reaction is completed, 5 g of 4-carboxyphenylboronic acid and 2 g of catalyst 4-dimethylaminopyridine are added thereto, and the reaction is continued at 75 °C for 2 h. After the reaction is completed, it is filtered, washed, and dried to obtain the compound modified attapulgite.

[0075] In Comparative Example 3 compared with Example 3, lauryl acrylate was not introduced.

[0076] Comparative Example 4

[0077] A preparation method of PVC pipes, comprising the following steps:

[0078] Add 65 parts of PVC resin, 25 parts of PE resin, 20 parts of composite modified attapulgite clay, 15 parts of compatibilizer polyethylene grafted maleic anhydride, 5 parts of calcium zinc heat stabilizer, 6 parts of monoglyceryl stearate, 4 parts of polyethylene wax, 3 parts of antioxidant 1010 and 2 parts of ultraviolet absorber UV327 into a high-speed mixer and mix evenly. The mixing speed in the high-speed mixer is 1000 r / min, the mixing time is 10 min, and the mixing temperature is 120 °C. Then, extrude and pelletize in a twin-screw extruder. Set the temperature of the first zone of the extruder to 195 °C, the second zone to 190 °C, the third zone to 180 °C, the fourth zone to 175 °C, the fifth zone to 170 °C, and the head temperature to 165 °C. After cooling and shaping, PVC pipes are obtained.

[0079] Among them, the preparation method of the composite modified attapulgite clay is as follows:

[0080] S1. Dissolve 2 g of zinc nitrate and 4 g of manganese nitrate in 150 mL of deionized water, then add 15 g of attapulgite clay thereto, ultrasonically disperse evenly, then add 20 g of 1 mol / L oxalic acid solution thereto, stir at 60 °C for 6 h, filter, wash, dry, and calcine at 900 °C for 3 h to obtain attapulgite clay composite;

[0081] S2. Disperse 15 g of attapulgite clay composite in 150 mL of 80 wt% ethanol aqueous solution, then add 3 g of vinyltriethoxysilane thereto, stir at room temperature for 2 h, then filter, wash, dry to obtain double-bond modified attapulgite clay composite;

[0082] S3. Disperse 20 g of double-bond modified attapulgite clay composite in 150 mL of organic solvent DMF, then add 6 g of lauryl acrylate, 6 g of 2-butene-1,4-diol and 2 g of initiator azobisisobutyronitrile thereto, heat and stir for reaction at 75 °C under nitrogen atmosphere for 3 h. After the reaction is completed, filter, wash, dry to obtain the composite modified attapulgite clay.

[0083] Compared with Example 3, 4-carboxyphenylboronic acid was not introduced in Comparative Example 4.

[0084] Make the PVC pipes prepared in Examples 1-3 and Comparative Examples 1-4 into test specimens that meet the test specifications, and then conduct performance tests, specifically as follows:

[0085] Tensile strength test: Test according to standard GB / T 1040.2-2022, conduct parallel tests 3 times, and take the average value of the results;

[0086] Impact resistance test: The test was carried out in accordance with the standard GB / T 1043.2-2018, with 3 parallel tests, and the average value was taken as the result;

[0087] Limited oxygen index test: The test was carried out in accordance with the standard GB / T 2406.2-2009, with 3 parallel tests, and the average value was taken as the result;

[0088] Damp heat resistance test: The test specimens were placed in an environment of 85 °C and a relative humidity of 90%, taken out after 1000 h, and the tensile strength retention rate was tested.

[0089] The test results are shown in Table 1.

[0090] Table 1 Performance test results of different examples and comparative examples

[0091]

[0092] As can be seen from Table 1, in Comparative Example 2, zinc oxide and manganese oxide were not loaded on attapulgite, and the flame retardancy was significantly reduced. In Comparative Example 3, lauryl acrylate was not introduced. In Comparative Example 4, 4-carboxyphenylboronic acid was not introduced. Their mechanical properties and damp heat resistance were significantly inferior to those of the examples of the present invention. The PVC pipes prepared in the examples of the present invention have excellent mechanical properties, flame retardancy and damp heat aging resistance.

[0093] Finally, it should be noted that the above examples do not limit the present invention in any form. For those skilled in the art, based on the present invention, some modifications and improvements can be made. Therefore, any modification or improvement made without departing from the spirit of the present invention falls within the scope of protection required by the present invention.

Claims

1. A PVC pipe composition, characterized in that, Raw materials comprising the following components by weight parts: 60 - 80 parts of PVC resin, 20 - 30 parts of PE resin, 15 - 25 parts of composite modified attapulgite clay, 10 - 20 parts of compatibilizer, 4 - 6 parts of heat stabilizer, 5 - 10 parts of lubricant, 1 - 3 parts of antioxidant, 1 - 2 parts of ultraviolet absorber; Among them, the preparation method of the composite modified attapulgite clay is as follows: S1. Dissolve zinc nitrate and manganese nitrate in deionized water, then add attapulgite clay thereto, disperse evenly by ultrasonic wave, then add oxalic acid solution thereto, stir, filter, wash, dry and calcine to obtain attapulgite clay complex; S2. Disperse the attapulgite clay complex in an ethanol - aqueous solution, then add vinyltriethoxysilane thereto, stir and react, then filter, wash and dry to obtain a double - bond modified attapulgite clay complex; S3. Disperse the double - bond modified attapulgite clay complex in an organic solvent, then add acrylate, 2 - butene - 1,4 - diol and initiator thereto, heat and stir to react under a nitrogen atmosphere. After the reaction is completed, add 4 - carboxylphenylboronic acid and catalyst thereto, continue to react. After the reaction is completed, filter, wash and dry to obtain the composite modified attapulgite clay; In step S3, the number of carbon atoms of the acrylate ≥ 10.

2. The PVC pipe composition according to claim 1, characterized in that, In step S1, the mass ratio of zinc nitrate, manganese nitrate, attapulgite clay and oxalic acid solution is 2 - 4:2 - 4:10 - 15:20 - 30, and the concentration of the oxalic acid solution is 0.5 - 2 mol / L.

3. The PVC pipe composition according to claim 1, characterized in that, In step S2, the mass ratio of the attapulgite clay complex and vinyltriethoxysilane is 10 - 15:1 - 3.

4. The PVC pipe composition according to claim 1, characterized in that, In step S3, the mass ratio of the double - bond modified attapulgite clay complex, acrylate, 2 - butene - 1,4 - diol, initiator, 4 - carboxylphenylboronic acid and catalyst is 10 - 20:3 - 6:3 - 6:1 - 2:3 - 5:1 - 2.

5. The PVC pipe composition according to claim 1, wherein, In step S3, the initiator is selected from benzoyl peroxide or azobisisobutyronitrile, and the catalyst is selected from 4 - dimethylaminopyridine.

6. The PVC pipe composition according to claim 1, characterized in that, The compatibilizer is selected from ethylene - vinyl acetate grafted maleic anhydride or polyethylene grafted maleic anhydride; The heat stabilizer is selected from calcium - zinc heat stabilizer or organotin heat stabilizer; The lubricant is selected from one or more of calcium stearate, polyethylene wax, stearic acid, monoglyceride stearate; 7. The PVC pipe composition according to claim 1, characterized in that, The antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, antioxidant DLTDP; The ultraviolet absorber is selected from one or more of titanium dioxide, UV328, UV327, UV326.

8. A preparation method of a PVC pipe, characterized in that, Including the following steps: Add the raw materials of the PVC pipe composition according to any one of claims 1 - 7 to a high - speed mixer in accordance with the formula ratio, mix evenly, then extrude and pelletize in a twin - screw extruder, and then cool and shape to obtain the PVC pipe.

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