High-antioxidant easy-to-demould ultra-high molecular weight polyethylene powder composition and preparation method thereof

Abstract

According to the high-antioxidant easy-to-demould ultra-high molecular weight polyethylene powder composition and the preparation method thereof, an additive mixture of a main antioxidant, an auxiliary antioxidant, a halogen absorbent and a slipping agent is added in the production process, and a low-melting-point additive combination formula is preferably selected through additive formula screening and combination, so that the high-antioxidant easy-to-demould ultra-high molecular weight polyethylene powder composition is prepared. The combined formula has the characteristics of low melting point, high dispersity and the like, and can enhance the aging resistance, the lubricity and the easy demolding performance of the product, so that the product can be applied to the manufacturing field of ultra-high molecular weight polyethylene covering fibers, plates, medical polymers and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material production, and particularly relates to a highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition and a preparation method thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a high-performance polymer material. Each molecular chain contains 100,000 to 250,000 structural units. The highly oriented and crystallinity of its molecular chains endows UHMWPE with many unique properties, such as excellent impact resistance, high tensile strength, self-lubrication, wear resistance, chemical resistance, stress cracking resistance, and anti-adhesion capabilities, resulting in a wide range of applications. However, due to its extremely high molecular weight (molecular weight > 100w), UHMWPE suffers from very poor processing performance and poor demolding properties during downstream product manufacturing. In particular, UHMWPE cannot be pelletized and stored like ordinary polyethylene and must be stored as a powder. However, chemical additives such as antioxidants and light stabilizers cannot usually be added to powders. Therefore, when exposed to light and heat, UHMWPE powder undergoes chemical reactions such as degradation, significantly reducing the physical properties of the UHMWPE product. This results in disadvantages such as a short shelf life and poor processing performance. Summary of the Invention

[0003] (1) Technical issues to be solved

[0004] The present invention provides a highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition and a preparation method thereof, in order to solve the technical problems of traditional ultra-high molecular weight polyethylene powder such as poor processing fluidity, poor demoulding properties, and easy degradation and aging.

[0005] (2) Technical solution

[0006] In order to solve the above technical problems, the present invention proposes a method for preparing a highly antioxidant and easily demoldable ultra-high molecular weight polyethylene powder composition. The preparation method comprises the following steps: mixing a primary antioxidant, an auxiliary antioxidant, a halogen absorber and a lubricant to obtain an additive mixture; discharging the ultra-high molecular weight polyethylene powder through a rotary valve in a degassing bin into an air conveying pipeline for transportation; discharging the additive mixture through the rotary valve into the air conveying pipeline, and forming a highly antioxidant and easily demoldable ultra-high molecular weight polyethylene powder composition in powder form through air conveying and mixing.

[0007] Furthermore, the primary antioxidant, the auxiliary antioxidant, the halogen absorber and the lubricant are mixed in a low-speed mixer for 30 minutes while maintaining the mixing temperature not higher than 40° C. to obtain an additive mixture.

[0008] Furthermore, the temperature of the ultra-high molecular weight polyethylene powder is maintained above 80° C. during the production process.

[0009] Furthermore, the main antioxidant is one of antioxidant 1010 and antioxidant 1076, or a mixture of the two.

[0010] Furthermore, the auxiliary antioxidant is one of antioxidant 618 and dilauryl thiodipropionate, or a mixture of the two.

[0011] Furthermore, the halogen absorber is zinc stearate, calcium stearate or a mixture of the two.

[0012] Furthermore, the lubricant is one of erucamide and oleamide, or a mixture of the two.

[0013] Furthermore, the ultra-high molecular weight polyethylene powder is produced by using polymerization grade ethylene in the presence of a Ziegler-Natta catalyst, the residual titanium element in the powder is ≤10 ppm, and the powder temperature is maintained at >80°C.

[0014] In addition, the present invention also proposes a highly antioxidant and easily demoldable ultra-high molecular weight polyethylene powder composition, which is prepared by the above method and includes the following components in parts by mass: 100 parts of ultra-high molecular weight polyethylene powder; 0.02 to 0.1 parts of a primary antioxidant; 0.02 to 0.2 parts of an auxiliary antioxidant; 0.1 to 0.3 parts of a halogen absorber; and 0.05 to 0.2 parts of a lubricant; wherein the viscosity-average molecular weight of the ultra-high molecular weight polyethylene powder is 70 to 200w.

[0015] Furthermore, the oxidation induction time of the highly antioxidant and easy-to-release ultra-high molecular weight polyethylene powder composition is greater than 50 min @ 190 ° C; the density is 0.920 to 0.960 kg / m 3 Melt flow rate <0.2g / 10min@190℃, 21.6kg weight; tensile yield stress ≥35.0MPa; tensile nominal strain at break ≥300%; demolding time ≤40s.

[0016] (3) Beneficial effects

[0017] The present invention provides a highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition and a preparation method thereof. During the production process, an additive mixture of a primary antioxidant, a secondary antioxidant, a halogen absorber and a lubricant is added. By screening and combining the additive formula, a low-melting-point additive combination formula is optimally selected. The combination formula has the characteristics of low melting point and high dispersibility, can enhance the aging resistance, lubricity and easy demoulding performance of the product, and can be applied to ultra-high molecular weight polyethylene manufacturing fields covering fibers, plates and medical polymers. DETAILED DESCRIPTION

[0018] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the embodiments.

[0019] Example 1

[0020] This embodiment provides a method for preparing a highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition, the preparation method comprising the following steps:

[0021] 10100.03 parts of antioxidant, 6180.06 parts of antioxidant, 0.1 part of zinc stearate and 0.1 part of erucamide are mixed in a low-speed mixer for 30 minutes, and the mixing temperature is maintained at not higher than 40°C to obtain an additive mixture; during the production process, the temperature of the ultra-high molecular weight polyethylene powder is maintained above 80°C, 100 parts of the ultra-high molecular weight polyethylene powder is discharged through a rotary valve in a degassing bin into an air conveying pipeline for transportation, the additive mixture is measured by a loss-in-weight scale, and then discharged through a rotary valve into an air conveying pipeline, and a high-antioxidant and easy-to-remove ultra-high molecular weight polyethylene powder composition in powder form is formed by air conveying and mixing.

[0022] Example 2

[0023] 10760.05 parts of antioxidant, 0.1 parts of dilauryl thiodipropionate, 0.2 parts of calcium stearate and 0.2 parts of oleamide were mixed in a low-speed mixer for 30 minutes, maintaining the mixing temperature at no more than 40° C. to obtain an additive mixture. Other steps were the same as in Example 1.

[0024] Example 3

[0025] 0.02 parts of antioxidant 1010, 0.06 parts of antioxidant 618, 0.15 parts of calcium stearate and 0.1 parts of erucamide were mixed in a low-speed mixer for 30 minutes, maintaining the mixing temperature at no more than 40° C. to obtain an additive mixture. Other steps were the same as in Example 1.

[0026] The performance parameters of the three embodiments are compared as follows:

[0027]

[0028] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition, characterized in that: The preparation method comprises the following steps: mixing a primary antioxidant, an auxiliary antioxidant, a halogen absorber and a lubricant to obtain an additive mixture; discharging ultra-high molecular weight polyethylene powder through a rotary valve in a degassing bin into an air delivery pipeline for transportation; discharging the additive mixture through the rotary valve into the air delivery pipeline, and forming a high-antioxidant and easy-to-release ultra-high molecular weight polyethylene powder composition in the form of powder by air delivery and mixing.

2. The method for preparing a highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The primary antioxidant, the auxiliary antioxidant, the halogen absorber and the lubricant were mixed in a low-speed mixer for 30 minutes while maintaining the mixing temperature not higher than 40° C. to obtain an additive mixture.

3. The method for preparing the highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The temperature of ultra-high molecular weight polyethylene powder is kept above 80°C during the production process.

4. The method for preparing a highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The main antioxidant is one of antioxidant 1010 and antioxidant 1076, or a mixture of the two.

5. The method for preparing the highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The auxiliary antioxidant is one of antioxidant 618 and dilauryl thiodipropionate, or a mixture of the two.

6. The method for preparing the highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The halogen absorber is one of zinc stearate and calcium stearate or a mixture of the two.

7. The method for preparing a highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The lubricant is one of erucamide and oleamide or a mixture of the two.

8. The method for preparing a highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition according to claim 1, wherein: The ultra-high molecular weight polyethylene powder is produced by using polymerization grade ethylene under the action of a Ziegler-Natta catalyst, the residual titanium element in the powder is ≤10 ppm, and the powder temperature is maintained at >80°C.

9. A highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition, characterized in that: The highly antioxidant and easily demoulding ultra-high molecular weight polyethylene powder composition is prepared by the method described in any one of claims 1 to 8, and comprises the following components in parts by weight: 100 parts of ultra-high molecular weight polyethylene powder; 0.02 to 0.1 parts of a primary antioxidant; 0.02 to 0.2 parts of an auxiliary antioxidant; 0.1 to 0.3 parts of a halogen absorber; and 0.05 to 0.2 parts of a lubricant; wherein the viscosity-average molecular weight of the ultra-high molecular weight polyethylene powder is 70 to 200w.

10. The highly antioxidant and easily demouldable ultra-high molecular weight polyethylene powder composition according to claim 9, characterized in that: The oxidation induction time of the highly antioxidant and easy-to-release ultra-high molecular weight polyethylene powder composition is greater than 50 minutes at 190°C; the density is 0.920 to 0.960 kg / m 3 Melt flow rate <0.2g / 10min@190℃, 21.6kg weight; tensile yield stress ≥35.0MPa; tensile nominal strain at break ≥300%; demolding time ≤40s.

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