Search

CN-122008432-A - Toughening additive suitable for melt extrusion molding and application method of toughening additive in polyethylene

CN122008432ACN 122008432 ACN122008432 ACN 122008432ACN-122008432-A

Abstract

The invention relates to the technical field of polyethylene modification, and discloses a toughening additive suitable for melt extrusion molding and an application method thereof in polyethylene. The invention discovers a matching mechanism between different length-diameter ratios of the toughening aid and different density polyethylenes, and according to the density of the polyethylenes, the polyethylene resin raw materials, the toughening aid corresponding to the length-diameter ratios and the composite antioxidant are melt blended according to a certain proportion to obtain the modified polyethylene composite material, and the toughness of the obtained material can be improved by 20-300% compared with that of the polyethylene resin raw materials.

Inventors

  • CHEN YUMING
  • ZHAN KENAN
  • DI YUTAO
  • SHI XUANYU
  • LI WEI
  • WANG JINGDAI
  • YANG YONGRONG

Assignees

  • 浙江大学

Dates

Publication Date
20260512
Application Date
20260130

Claims (10)

  1. 1. The polyethylene melt extrusion molding method based on the toughening aid is characterized by comprising the following steps of: 1) Selecting a toughening auxiliary agent with an adaptive length-diameter ratio according to the density of the polyethylene resin raw material, wherein the polyethylene resin raw material with the density of 0.940-0.960g/cm 3 is selected, the toughening auxiliary agent with the length-diameter ratio of 50-200:1 is selected, the polyethylene resin raw material with the density of less than 0.940g/cm 3 and more than 0.920 g/cm 3 is selected, the toughening auxiliary agent with the length-diameter ratio of 20-49:1 is selected, and the polyethylene resin raw material with the density of 0.860-0.920 g/cm 3 is selected, and the toughening auxiliary agent with the length-diameter ratio of 1-19:1 is selected; 2) Uniformly mixing a polyethylene resin raw material, the toughening additive and the antioxidant which are matched in the step 1); 3) And (3) carrying out melt extrusion granulation on the mixture obtained in the step (2) through a double-screw extruder to obtain the modified polyethylene composite material.
  2. 2. The method according to claim 1, wherein the melting point of the toughening agent is higher than the melt extrusion processing temperature, and the length of the toughening agent in the x, y and z directions in the three-dimensional space is not more than 200 μm.
  3. 3. The method of claim 1, wherein the toughening aid is one or more of sorbitol nucleating agent, aliphatic carboxylic acid metal compound, aromatic carboxylic acid metal compound, organic phosphate, wood acid and derivatives thereof, metal, non-metal solid oxide, and non-metal simple substance.
  4. 4. A method of melt extrusion of polyethylene according to claim 3, wherein the toughening aid is preferably a sorbitol nucleating agent comprising one or more of 1,3-2, 4-di (p-methyl) benzyl sorbitol, 1,3-2, 4-di (p-ethyl) benzyl sorbitol, di (3, 4-dimethyl dibenzylidene) sorbitol.
  5. 5. The method of melt extrusion molding of polyethylene according to claim 4, wherein when sorbitol nucleating agent is selected as the toughening aid, at least one of the following methods is further employed to obtain the toughening aid of desired aspect ratio: (1) Dissolving sorbitol nucleating agent raw materials in a solvent, recrystallizing at 80-100 ℃, filtering a hot solution through a preheated funnel, slowly cooling filtrate to 20-25 ℃ at a cooling rate of 1-2 ℃ per hour, standing the filtrate at 0-5 ℃ for different times, and obtaining sorbitol nucleating agent crystals with different length-diameter ratios through the difference of standing time; (2) The solvent polarity regulating process includes dissolving sorbitol nucleator material in solvent of required polarity, adding sorbitol nucleator seed crystal, cooling and crystallizing the solution to obtain toughening assistant of required length-diameter ratio; (3) And the physical grinding adjustment method is to put sorbitol nucleating agent raw materials into a ball mill, and obtain the sorbitol nucleating agent with the required length-diameter ratio through adjusting and controlling grinding time.
  6. 6. The method for melt extrusion molding of polyethylene according to claim 1, wherein the weight ratio of the components in the step 2) is 98.5-99.7 wt% of polyethylene resin raw material, 0.2-1.0 wt% of toughening aid and 0.1-0.5 wt% of antioxidant.
  7. 7. The method for melt extrusion molding of polyethylene according to claim 6, wherein the antioxidant is a composite antioxidant comprising a first antioxidant and a second antioxidant in a weight ratio of 0.5-2:1; The first antioxidant and the second antioxidant are respectively selected from one or more of antioxidant 264, antioxidant 1010, antioxidant 1024, antioxidant 1076, antioxidant 168 and antioxidant B215.
  8. 8. The method of claim 1, wherein the temperature of the melt extrusion granulation is 170-230 ℃ and the rotational speed is 50-300 rpm.
  9. 9. A modified polyethylene composite prepared by the method of any one of claims 1-8.
  10. 10. The modified polyethylene composite material according to claim 9, wherein the modified polyethylene composite material has a crystallinity increased by 5 to 10% and a toughness increased by 20 to 300% compared to a polyethylene resin raw material before modification.

Description

Toughening additive suitable for melt extrusion molding and application method of toughening additive in polyethylene Technical Field The invention relates to the technical field of polyethylene modification, in particular to a toughening additive suitable for melt extrusion molding and an application method thereof in polyethylene. Background Polyethylene (PE) is used as one of five synthetic resins, and has the advantages of wide source, low price and the like by virtue of good processability, mechanical property, chemical corrosion resistance and low temperature resistance, and is widely applied to the fields of films, packages, pipes, sheets, fibers and the like. Polyethylene has the advantages of low cost, good processability and the like, but the characteristics of insufficient impact strength and tensile strength become key bottlenecks for limiting the deep application of the polyethylene in the high-end field. In the manufacture of automobile parts, taking a bumper as an example, when a traditional polyethylene-based material is subjected to medium-low speed collision, the traditional polyethylene-based material is easy to crack due to insufficient impact strength, and collision energy cannot be effectively absorbed. Polyethylene is a semi-crystalline polymer, and its crystallization behavior, morphology and content of crystalline and amorphous regions directly affect the processing and application properties of polyethylene articles. The nucleating agent is a polymer modification auxiliary agent, is mainly used for improving the performance of polyolefin, can accelerate the crystallization rate, improve the crystallization density and promote the grain size to be miniaturized, achieves the purposes of shortening the molding cycle, improving the transparency, surface gloss, tensile strength, impact resistance, heat distortion temperature, creep resistance and other physical and mechanical properties of products, and can be applied to the fields of food contact materials, medical appliances, automobile parts, building materials and the like. In actual production, the polyethylene-filled filler is selected from calcium carbonate, talcum powder, calcium silicate, stearate nucleating agent, parahydroxybenzoic acid nucleating agent, etc. Although the common nucleating agent filled polyethylene composite material can reduce the cost of products and improve the rigidity, the heat resistance and the dimensional stability, the interface adhesion of the non-polar high polymer polyethylene is poor, the dispersibility is poor and the polyethylene composite material is easy to separate out, so that the mechanical property and the flow property of the material are reduced, and the common nucleating agent filled polyethylene composite material has obvious limitations in application scenes, raw material suitability and industrial operation. The Chinese patent CN 117986717A discloses a formula mixing process of high-density polyethylene and calcium carbonate, the scheme focuses on improving the rigidity, hardness, dimensional stability and other performances of materials to be obviously improved, and has the advantages of good wear resistance, weather resistance and the like, but on one hand, the particle size range of the calcium carbonate in the scheme is 10-30 mu m, the application scene is limited due to the too narrow particle size range, and on the other hand, the toughness of the product is reduced due to the smaller particle size of the calcium carbonate, so that the contradiction between the rigidity and the toughness is not solved. Chinese patent CN116355301 a discloses a composite material of a film blowing grade of polyethylene modified by straw fiber and talcum powder, which reduces the surface polarity of talcum powder by utilizing the compatibility between straw fiber and talcum powder and organic polymer material, but the process for preparing straw fiber is very complex, and the mechanical properties such as tensile strength, elongation at break, yield strength and elastic modulus of the improved polyethylene film are not explicitly described. Chinese patent CN 108559164A discloses a high-content calcium silicate filled polyethylene master batch and a preparation method thereof, a carrier is only limited to low-density polyethylene, and the carrier cannot be directly applied to other polyethylene products such as high-density polyethylene, linear low-density polyethylene and the like, the application range is narrow, and a short plate exists for improving the performance. In order to solve the defects of poor interfacial adhesion, poor dispersibility and easy precipitation of the polyethylene composite material filled with the traditional nucleating agent, a toughening additive suitable for polyethylene melt extrusion molding and an application method thereof are researched and developed. Disclosure of Invention The invention aims to solve the problem that the application of the traditional nucleati