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CN-121975219-A - Polyethylene polypropylene blend standard test piece for tax identification and preparation method thereof

CN121975219ACN 121975219 ACN121975219 ACN 121975219ACN-121975219-A

Abstract

The invention provides a polyethylene polypropylene blend standard test piece for tax identification and a preparation method thereof, belonging to the technical field of polyethylene polypropylene blend content detection. The invention uses linear low density polyethylene resin and homo-polypropylene resin as main components, antioxidant anti-aging, improves the stability of the standard test piece, uses dispersing agent and lubricant to improve dispersion effect, improves the uniformity of the standard test piece, nucleating agent improves the crystallinity of the standard test piece, improves long-term storage stability, and the components cooperate to obtain the tax identification polyethylene polypropylene blend standard test piece with good uniformity and excellent long-term storage stability. The preparation method provided by the invention has a simple process, and the prepared standard sample can be directly used for customs laboratory identification, laboratory detection method verification, product quality control of regenerated plastic production enterprises, evaluation of measurement uncertainty, assessment of personnel training and the like.

Inventors

  • LUO CHUAN
  • YUAN LIFENG
  • WANG HAO
  • NI FENGPING
  • ZHANG YING

Assignees

  • 宁波海关技术中心

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. The polyethylene polypropylene blend standard test piece for tax identification is characterized by comprising, by mass, 90-100 parts of linear low-density polyethylene resin, 3-8 parts of homo-polypropylene resin, 0.1-6 parts of antioxidant, 0.03-6 parts of dispersing agent, 0.03-6 parts of lubricant and 0.03-6 parts of nucleating agent.
  2. 2. The tax return polyethylene polypropylene blend standard test piece according to claim 1, wherein the linear low density polyethylene resin has a density of 0.915 g/cm 3 and the linear low density polyethylene resin has a melt mass flow rate MFR of 1.98.0 g/10 min.
  3. 3. The tax banded polyethylene polypropylene blend standard test piece according to claim 1, wherein the homo-polypropylene resin has a density of 0.900 g/cm 3 and a melt mass flow rate MFR of 3.21g/10 min.
  4. 4. A method for preparing a standard test piece of polyethylene polypropylene blend for tax identification according to any one of claims 1 to 3, comprising the steps of: (1) Mixing linear low-density polyethylene resin, homo-polypropylene resin, an antioxidant, a dispersing agent, a lubricant and a nucleating agent to obtain a mixed material; (2) Sequentially carrying out first melting, mixing and extrusion, first cooling and first granulating on the mixed material obtained in the step (1) to obtain sample particles; (3) Stirring and mixing the sample particles obtained in the step (2), carrying out second melt mixing extrusion, second cooling and second granulating and forming in sequence to obtain blend standard sample particles; (4) And (3) sequentially carrying out injection molding and room temperature drying airtight preservation on the blend standard sample particles obtained in the step (3) to obtain a polyethylene polypropylene blend standard test piece for tax identification.
  5. 5. The preparation method of claim 4, wherein the mixing in the step (1) is performed at 40 ℃ and a rotation speed of 50 r/min for 22-26 h.
  6. 6. The preparation method of the die-casting die disclosed by claim 4, wherein the equipment used for the first melt mixing extrusion in the step (2) is a four-section heating type double-screw extruder, and parameters of the four-section heating type double-screw extruder comprise a feed port temperature of 80-100 ℃, a first heating section temperature of 180-210 ℃, a second heating section temperature of 180-210 ℃, a third heating section temperature of 190-220 ℃, a fourth heating section temperature of 200-230 ℃, a die temperature of 210-240 ℃, a screw speed of 150-300 r/min and a granulator speed of 200-500 r/min.
  7. 7. The process of claim 4, wherein the first cooling in step (2) is performed by cooling the first melt-mixed extruded product with water at a temperature of 60 ℃ or less.
  8. 8. The preparation method of claim 4, wherein the stirring and mixing in the step (3) is performed at a rotation speed of 50 r/min for 11-14 h.
  9. 9. The method according to claim 4, wherein the injection molding parameters in the step (4) include 190-210 ℃ melt temperature, 40-60 ℃ mold temperature, 25-30 cm 3 /s average injection rate, 40-60 s dwell time, 60-80 s total circulation time, 500-1000 psi injection pressure, 25-30 cm 3 /s injection speed, 1.0-2.0 s injection time, 300-500 psi dwell pressure, 2.5-7.5 cm 3 /s dwell speed, and 35-50 cm 3 of melt adhesive.
  10. 10. The method according to claim 4, wherein the front 10 molds are discarded during the injection molding in the step (4), and the tax collection of the sample from the 11 th mold is started to identify the polyethylene polypropylene blend standard test piece.

Description

Polyethylene polypropylene blend standard test piece for tax identification and preparation method thereof Technical Field The invention relates to the technical field of content detection of polyethylene polypropylene blends, in particular to a polyethylene polypropylene blend standard test piece for tax identification and a preparation method thereof. Background The commodity name and code coordination system is simply called as coordination system (HS), and is a commodity classification coding system for customs, statistics, import and export management and common use with all parties related to international trade, which is formulated by the World Customs Organization (WCO) host, and the HS is formally implemented in 1 month and 1 day of 1988 and revised 1 time in 4-6 years. More than 200 countries in the world use HS, and more than 98% of the global trade total is classified by HS. The HS system of the world customs organization is implemented in 1 month of 1992 in China, and the tax import and export law and the customs statistics commodity catalogue of China are compiled according to the HS system, the tax import and export of China adopts ten codes, the first eight bits are equivalently used for HS coding, the second two bits are sub-catalogues of China, and the two bits are extended according to the actual conditions of the imported and exported commodities of China on the basis of the HS classification principle and method. HS classifies all International trade commodities into 22 classes, chapter 98, with chapter 7 and chapter 39 being plastics and their products. The plastic and its products are widely used in economic and social development due to the characteristics of convenient processing, economy and practicality, etc., and a large amount of plastic raw materials are imported every year in China, but the plastic is not a single component substance, and can be polymerized by a certain monomer, can be copolymerized by two or more monomers, and can be blended by two or more polymers. The complexity of the composition brings great difficulty to the HS classification assay work. In the imported plastics, the olefin polymers (including polyethylene, polypropylene and the like) account for more than 50% of the total imported plastics, so that the main technical problems are concentrated in tax classification tests of the olefin polymers. For example, the identification of propylene monomer content in the goods commonly reported under the names "polyethylene and polypropylene blend reclaimed particles" and "ethylene propylene copolymer reclaimed particles" is defined by the terms "copolymer and polymer blend" according to the tax and item notes of the year 2022, "copolymer and polymer blend" as including various polymers having 95% or more of the content of none of the monomer units by weight in the whole polymer, such as reclaimed polyethylene having a polypropylene content of more than 5%, due to ethylene-propylene copolymer (under the term 390190, tax rate of 4.2% in the asian region), such as polypropylene having a content of less than 5%, due to other terms (tax rate of 6% in the asian region), and due to the tax difference, some enterprises in recent years intentionally report reclaimed polyethylene as reclaimed particles of ethylene propylene copolymer or reclaimed particles of polyethylene/polypropylene blend, etc., to influence normal tax collection work in order to evade money. There are many articles on the polyethylene and polypropylene blend at home and abroad, but the characterization of new materials is focused, the research on reclaimed materials is less, and the standards for determining the polyethylene and polypropylene blend mainly comprise SN/T3298-2012 methods for determining propylene unit content in import and export ethylene-propylene copolymer developed by the laboratory, infrared spectrometry, and determination of ethylene in SH/T1751-2005 ethylene-propylene copolymer (EPM) and ethylene-propylene-diene terpolymer (EPDM), the SN/T3298 is mainly made of new materials, the blend with propylene as a main content is mainly made of the blend, the measurement range is that the propylene unit content is 82% -96%, the SH/T1751 is mainly made of ethylene propylene rubber, the measurement range is that the ethylene unit content is 35% -85%, the above standards are not suitable for identifying the polypropylene content in the regenerated polyethylene, and in daily tariff tests, only whether the ethylene monomer content in the regenerated polyethylene is more than 95% is required to be identified. Therefore, there is a need to provide a standard sample that can identify the small amount of polypropylene content in polyethylene polypropylene blends to meet the needs of the customs sector for daily regulations and the needs of the quality control of recycled plastic manufacturing enterprises. Disclosure of Invention The invention aims to provide a polyethylene polypropylene blend standa