Self-lubricating wear-resistant polypropylene composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polypropylene composite materials, in particular to a self-lubricating wear-resistant polypropylene composite material as well as a preparation method and application thereof, and the self-lubricating wear-resistant polypropylene composite material comprises the following raw materials in percentage by weight: 84.7-91.9% of polypropylene, 3-6% of castor oil, 5-9% of GMA graft modified elastomer and 0.1-0.3% of antioxidant. The GMA grafted modified elastomer is added as a compatilizer, an epoxy group energy group in GMA can react with hydroxyl of a hydrogenated castor oil molecular chain, the interface bonding force of hydrogenated castor oil and a polypropylene material is improved, according to the self-lubricating polypropylene blend prepared through the method, the compatibility of hydrogenated castor oil and polypropylene becomes good, the dispersity is improved, and the self-lubricating polypropylene blend can be applied to the field of polypropylene materials. The hydrogenated castor oil is not easy to separate out, and the mechanical property of the polypropylene is not deteriorated.

Description

Technical Field

[0001] This invention relates to the field of polypropylene composite materials technology, and in particular to a self-lubricating and wear-resistant polypropylene composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) is a semi-crystalline thermoplastic polymer made from propylene monomers through an addition polymerization reaction. PP is widely used in the medical device field due to its good biocompatibility, mechanical strength, light weight, low cost, and non-toxicity. The medical industry places high demands on the self-lubricating properties, low-temperature resistance, and mechanical properties of PP materials. Unmodified PP has poor self-lubrication and wear resistance, which limits its application in the medical catheter industry to some extent. To improve the self-lubricating properties of PP materials, a common method is to add stearic acid, fatty acid esters, and fluoropolymers to the PP system.

[0003] Patent CN111320819A discloses a low-cost food-grade self-lubricating polypropylene material and its preparation method. The self-lubricating properties of the polypropylene material are improved by adding erucamide small molecule lubricant. However, this method achieves the self-lubricating effect by precipitating small molecule lubricant, which has unstable effect, deteriorates the self-lubricating performance after long-term use, and is prone to stickiness and other appearance problems at high temperatures.

[0004] Patent CN 112391006A discloses a wear-resistant and self-lubricating polypropylene alloy composition. Through the synergistic effect of high-density polyethylene and long-chain nylon, the wear resistance and self-lubricating properties of polypropylene are greatly improved. Although the wear resistance effect does not decrease with use, the method has limited improvement on lubrication performance and cannot meet the requirements of high lubrication effect.

[0005] Patent CN107603031A discloses a TiO2-BaSO4 modified low surface energy, self-lubricating polypropylene flat-wall reinforced IFB corrugated pipe and its preparation method. By constructing a "roller structure model" and adding ultra-high molecular weight polyethylene, the friction coefficient of the corrugated pipe is reduced. However, this method has the disadvantages of being difficult to process ultra-high molecular weight polyethylene and difficult to injection mold. At the same time, the processing steps are complex and not easy to operate, and it is only suitable for extruded pipes.

[0006] Although the self-lubricating PP prepared above can improve the self-lubricating properties of the material, the self-lubricating PP prepared by simple physical blending has poor compatibility between the lubricant and polypropylene, the lubricant is easy to precipitate, and it will deteriorate the mechanical properties of polypropylene. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide a self-lubricating wear-resistant polypropylene composite material, its preparation method and application, in order to solve the problems of poor compatibility between existing lubricants and polypropylene, easy precipitation of lubricants, and deterioration of the mechanical properties of polypropylene.

[0008] To achieve the above objectives, the present invention provides a self-lubricating and wear-resistant polypropylene composite material, comprising the following raw materials by weight percentage:

[0009] Polypropylene 84.7-91.9%

[0010] Castor oil 3-6%

[0011] GMA-grafted modified elastomer 5-9%

[0012] Antioxidant 0.1-0.3%.

[0013] The castor oil is hydrogenated castor oil.

[0014] The GMA-grafted modified elastomer is one or more of ethylene-ethyl acrylate-GMA grafts, ethylene-propylene-GMA grafts, and ethylene-octene-GMA grafts. Preferably, it is an ethylene-ethyl acrylate-GMA graft.

[0015] The grafting rate of GMA in the GMA-grafted modified elastomer is 1.5-2%.

[0016] The polypropylene is one or both of atactic polypropylene and homopolymer polypropylene. Atactic polypropylene is preferred.

[0017] The polypropylene is atactic polypropylene with an ethylene content of 5-7 wt%.

[0018] The antioxidant is at least one of phosphite antioxidants, hindered phenolic antioxidants, and thioether antioxidants. Hindered phenolic antioxidants are preferred.

[0019] The present invention also provides a method for preparing the self-lubricating wear-resistant polypropylene composite material. The method involves first blending GMA grafted modified elastomer and hydrogenated castor oil according to the formula amount, then blending them with polypropylene and antioxidants, and finally obtaining the self-lubricating polypropylene blend by melt extrusion granulation.

[0020] Preferably, the granulation is carried out by melt extrusion using a twin-screw extruder, with the following temperature conditions: Zone 1: no heating; Zone 2: 170–180°C; Zone 3: 210–220°C; Zones 4–8: 230–245°C; Zones 9–10: 210–220°C; Zones 11–14: 190–200°C; Die head: 170–180°C; Main extruder speed: 500–600 rpm.

[0021] The present invention also provides the application of the self-lubricating and wear-resistant polypropylene composite material in medical catheter products.

[0022] The beneficial effects of this invention are as follows: By adding GMA-grafted modified elastomer as a compatibilizer, the epoxy groups in GMA can react with the hydroxyl groups of hydrogenated castor oil molecular chains, thereby improving the interfacial bonding force between hydrogenated castor oil and polypropylene materials. The self-lubricating polypropylene blend prepared by this method has better compatibility and dispersibility between hydrogenated castor oil and polypropylene, is less prone to precipitation of hydrogenated castor oil, and does not deteriorate the mechanical properties of polypropylene. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the product obtained in Embodiment 3 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0026] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0027] Example 1

[0028] The preparation of the self-lubricating and wear-resistant polypropylene composite blend in this embodiment includes the following raw materials by weight percentage:

[0029] The composition includes 91.9% atactic polypropylene, 5% ethylene-ethyl acrylate-GMA graft, 3% hydrogenated castor oil, and 0.1% antioxidant. Among these, the ethylene content in the atactic polypropylene is 6 wt%, the grafting rate of GMA in the ethylene-ethyl acrylate-GMA graft is 1.5%, and the antioxidant is antioxidant 1010.

[0030] The preparation method of this self-lubricating wear-resistant polypropylene composite material is as follows: GMA graft-modified elastomer and hydrogenated castor oil are first blended, allowing the hydrogenated castor oil to be preferentially distributed on the GMA graft-modified elastomer. Then, it is blended with polypropylene and antioxidant in the above manner and melt-extruded and granulated through a twin-screw extruder. The temperature conditions are as follows: Zone 1: no heating; Zone 2: 175±5℃; Zone 3: 215±5℃; Zones 4-8: 240±5℃; Zones 9-10: 215±5℃; Zones 11-14: 195±5℃; Die head: 175±5℃; Main engine speed: 450 rpm. The self-lubricating wear-resistant polypropylene composite material is obtained.

[0031] Examples 1-5 and Comparative Examples 1-4 were carried out according to the raw material components and formulation amounts in Table 1 below.

[0032] Table 1

[0033]

[0034] The polypropylene blends of Examples 1-5 and Comparative Examples 1-4 were injection molded into samples for performance testing. The test methods are as follows: tensile strength was tested according to DIN EN ISO 527-2 standard, speed 50 mm / min; cantilever beam notched impact strength was tested according to DIN EN ISO 180 standard; abrasion resistance was tested according to GB / T 1768-2006 standard, grinding wheel model: CS-10; load: 500g; number of cycles: 1500 times; rotation speed: 60 / 72 r·min; the samples were pre-equilibrated in a standard laboratory environment of (23±2)℃ & (50±5)% relative humidity for 24 hours before testing. The sample was placed in a standard laboratory environment at (23±2)℃ and (50±5)% relative humidity for 24 hours before testing. The sample size was a square plate with a length, width and thickness of 100mm*100mm*3mm. The friction coefficient was tested according to GB / T 10006-1988. The slider size was 63mm*63mm and the slider mass was 200±2g. The speed for dynamic friction coefficient testing was 100±10mm / min. For static friction coefficient testing, the spring elastic coefficient was 2±1N / cm and the sample size was 200mm*80mm. The sample was fixed to the lower end of the slider with double-sided tape.

[0035] The test results are shown in Table 2 below:

[0036] Table 2

[0037]

[0038] The performance results from the above examples and comparative examples show that the impact strength is basically the same when GMA-grafted elastomer and hydrogenated castor oil are added simultaneously, compared to when GMA-grafted elastomer is added alone. However, the impact strength decreases when hydrogenated castor oil is added alone. This proves that the epoxy functional groups in GMA and the hydroxyl groups in hydrogenated castor oil undergo reactive compatibilization. Furthermore, the introduction of GMA monomer improves the interfacial compatibility between non-polar polypropylene and polar hydrogenated castor oil, thus preventing the deterioration of the mechanical properties of the polypropylene material. Wear, dynamic friction coefficient, and static friction coefficient are significantly reduced, and notched impact strength is improved. Therefore, the addition of GMA-grafted elastomer and castor oil significantly improves the mechanical properties and self-lubricating properties of polypropylene materials.

[0039] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A self-lubricating and wear-resistant polypropylene composite material, characterized in that, The raw materials include the following weight percentages: Polypropylene 84.7-91.9% Castor oil 3-6% GMA-grafted modified elastomer 5-9% Antioxidant 0.1-0.3%.

2. The self-lubricating wear-resistant polypropylene composite material according to claim 1, characterized in that, The castor oil is hydrogenated castor oil.

3. The self-lubricating wear-resistant polypropylene composite material according to claim 1, characterized in that, The GMA-grafted modified elastomer is one or more of the following: ethylene-ethyl acrylate-GMA graft, ethylene-propylene-GMA graft, and ethylene-octene-GMA graft.

4. The self-lubricating wear-resistant polypropylene composite material according to claim 1, characterized in that, The grafting rate of GMA in the GMA-grafted modified elastomer is 1.5-2%.

5. The self-lubricating wear-resistant polypropylene composite material according to claim 1, characterized in that, The polypropylene is one or both of atactic polypropylene and homopolymer polypropylene.

6. The self-lubricating wear-resistant polypropylene composite material according to claim 5, characterized in that, The polypropylene is atactic polypropylene with an ethylene content of 5-7 wt%.

7. The self-lubricating wear-resistant polypropylene composite material according to claim 1, characterized in that, The antioxidant is at least one of phosphite antioxidants, hindered phenolic antioxidants, and thioether antioxidants.

8. The method for preparing the self-lubricating wear-resistant polypropylene composite material according to any one of claims 1-7, characterized in that, The preparation method involves first blending GMA-grafted modified elastomer and hydrogenated castor oil according to the formula, then blending them with polypropylene and antioxidants, and finally obtaining a self-lubricating polypropylene blend after melt extrusion granulation.

9. The method for preparing the self-lubricating wear-resistant polypropylene composite material according to claim 8, characterized in that, The pellets are melt-extruded using a twin-screw extruder with the following temperature conditions: Zone 1: no heating; Zone 2: 170–180℃; Zone 3: 210–220℃; Zones 4–8: 230–245℃; Zones 9–10: 210–220℃; Zones 11–14: 190–200℃; Die head: 170–180℃; Main extruder speed: 400–500 rpm.

10. The use of the self-lubricating wear-resistant polypropylene composite material according to any one of claims 1-7 in medical catheter products.

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