A polyoxymethylene resin composition and its preparation method and application

Abstract

The invention discloses a polyoxymethylene resin composition and a preparation method and application thereof. The polyoxymethylene resin composition comprises the following components by weight: 100 parts of polyoxymethylene resin; 5-15 parts of ultra-high molecular weight silicone; 5-8 parts of polytetrafluoroethylene; and 0.4-1.2 parts of high molecular weight polyethylene glycol. The polyoxymethylene resin composition provided by the invention has the characteristics of low friction coefficient, high wear resistance and low mold fouling, and can be applied to occasions with high requirements on lubricity, wear resistance and mold fouling.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering plastics, and specifically relates to a polyoxymethylene resin composition and a preparation method and application thereof. Background Art

[0002] As a highly crystalline engineering plastic, polyoxymethylene resin (POM) has excellent comprehensive mechanical properties, self-lubricating properties, wear resistance and fatigue resistance. It has the best lubricity among general engineering plastics and is widely used in products such as gears and bearings. However, in some application scenarios, POM still has problems such as too high friction coefficient and insufficient wear resistance, and needs to be coated with silicone grease to meet the requirements of the use environment. Summary of the invention

[0003] In order to overcome the defects of the prior art, the present invention provides a polyoxymethylene resin composition and a preparation method and application thereof. The polyoxymethylene resin composition provided by the present invention has the characteristics of low friction coefficient, high wear resistance and low mold fouling, and can be used in occasions with high requirements on lubricity, wear resistance and mold fouling.

[0004] This is achieved specifically through the following technical solutions:

[0005] A polyoxymethylene resin composition, comprising the following components in parts by weight:

[0006]

[0007] Furthermore, the polyoxymethylene resin is a copolymer polyoxymethylene resin and / or a homopolymer polyoxymethylene resin, the melt index of the polyoxymethylene resin is 2-27 g / 10 min, the test standard is ISO 1133-1-2012, and the test conditions are 190° C. and 2.16 KG.

[0008] Furthermore, the number average molecular weight of the ultra-high molecular weight silicone is more than 1 million, preferably 1-10 million. The ultra-high molecular weight silicone and polytetrafluoroethylene synergistically improve the wear resistance of the material. In addition, the ultra-high molecular weight silicone can also improve the lubricity of the material.

[0009] Specifically, the ultra-high molecular weight silicone can be used in the form of a masterbatch, and the carrier of the masterbatch can be selected from polyethylene, thermoplastic polyurethane elastomer (TPU) or polyoxymethylene resin. The most preferred masterbatch carrier is polyoxymethylene resin. The effective content of ultra-high molecular weight silicone in the ultra-high molecular weight silicone masterbatch is 30-50%.

[0010] Furthermore, the high molecular weight polyethylene glycol preferably has a number average molecular weight of 10000 to 20000. The high molecular weight polyethylene glycol plays a role in reducing mold deposit in the composition.

[0011] Specifically, the high molecular weight polyethylene glycol can also be used in the form of masterbatch, the carrier of the masterbatch can be selected from low density polyethylene, and the effective content of the high molecular weight polyethylene glycol in the high molecular weight polyethylene glycol masterbatch is 30-50%.

[0012] Furthermore, the polyoxymethylene resin composition further comprises 0-1 part of an auxiliary agent.

[0013] Furthermore, the auxiliary agent is one or more of an antioxidant, a formaldehyde absorber and a weathering agent, wherein the antioxidant includes a primary antioxidant and a secondary antioxidant.

[0014] Specifically, the antioxidant can be one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (primary antioxidant), di[3-(1,1-dimethylethyl)-4-hydroxy-5-methylphenylpropionic acid]triethylene glycol (primary antioxidant), pentaerythritol tetrakis(3-laurylthiopropionate) (secondary antioxidant) and tris[2,4-di-tert-butylphenyl]phosphite (secondary antioxidant); the aldehyde absorbing agent can be allantoin and / or Or ethylene bisstearamide; the weathering agent can be one or more of 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol and / or poly[[6-[(1,1,3,3-tetramethylbutyl)amine]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imine]-1,6-dihexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imine]]].

[0015] The present invention also provides a method for preparing the polyoxymethylene resin composition, comprising the following steps:

[0016] S1: Weigh each component according to the ratio, and premix the components to obtain a premix;

[0017] S2: adding the premix to an extruder, performing melt extrusion and granulation to obtain the polyoxymethylene resin composition.

[0018] Specifically, the extruder is a twin-screw extruder, and the temperatures of the screw barrels from the feeding port to the die are: 150℃-180℃, 170℃-220℃, 170℃-220℃, 170℃-210℃, 170℃-210℃, 170℃-200℃, 170℃-200℃, 170℃-200℃, 170℃-210℃, 170℃-220℃, the screw speed of the twin-screw extruder is 250 rpm-350 rpm, the feed rate is 50kg / h-200kg / h, and the vacuum degree is (-0.1)-0MPa.

[0019] The present invention also provides the use of the polyoxymethylene resin composition in the preparation of mechanical gears, bearings and daily consumer products, and is particularly suitable for the preparation of parts with high requirements on lubricity, wear resistance and mold fouling.

[0020] Beneficial effects:

[0021] The present invention adds ultra-high molecular weight silicone, polytetrafluoroethylene and high molecular weight polyethylene glycol to the polyoxymethylene resin, which not only greatly reduces the friction coefficient of the material and improves the wear resistance, but also can be widely used in occasions with high requirements for lubricity and wear resistance, especially in applications where silicone grease oil needs to be applied to the surface. The preparation method provided by the present invention is simple, low in cost and high in efficiency. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] <Preparation of Examples and Comparative Examples>

[0024] The raw materials used in the examples and comparative examples of the present invention are all self-made or commercially available, but are not limited to these materials:

[0025] Polyoxymethylene resin A: copolymer polyoxymethylene resin, brand POM M90-44, purchased from Nantong Baotai Ling;

[0026] Polyoxymethylene resin B: homopolymer polyoxymethylene resin, brand POM 500P, purchased from DuPont, USA;

[0027] Ultra-high molecular weight silicone A: number average molecular weight 1 million, Chongqing Baozhuan;

[0028] Ultra-high molecular weight silicone B: number average molecular weight 10 million, Chongqing Baozhuan;

[0029] Ultra-high molecular weight silicone C: number average molecular weight 500,000, Chongqing Baozhuan;

[0030] Ultra-high molecular weight silicone D: number average molecular weight 200 million, Chongqing Baozhuan;

[0031] Ultra-high molecular weight silicone masterbatch: The effective content of ultra-high molecular weight silicone in the masterbatch is 40wt%, the masterbatch carrier is polyoxymethylene resin, the number average molecular weight of the ultra-high molecular weight silicone in the masterbatch is 10000, the brand is ZP-10000, the manufacturer is Chongqing Baozhuan;

[0032] Polytetrafluoroethylene: brand F-5AEX R, purchased from Solvay;

[0033] High molecular weight polyethylene glycol A: number average molecular weight is 8000, brand name PEG-8000, purchased from Guangzhou Yuanda New Materials;

[0034] High molecular weight polyethylene glycol B: number average molecular weight is 10000, brand name PEG-10000, purchased from Guangzhou Yuanda New Materials;

[0035] High molecular weight polyethylene glycol C: number average molecular weight is 20000, brand name PEG-20000, purchased from Guangzhou Yuanda New Materials;

[0036] High molecular weight polyethylene glycol D: number average molecular weight is 2000, brand name PEG-2000, purchased from Guangzhou Yuanda New Materials;

[0037] High molecular weight polyethylene glycol E: number average molecular weight 25000, brand PEG-25000, purchased from Guangzhou Yuanda New Materials;

[0038] High molecular weight polyethylene glycol masterbatch: The effective content of high molecular weight polyethylene glycol in the masterbatch is 40wt%, the number average molecular weight of high molecular weight polyethylene glycol in the masterbatch is 20000, the masterbatch carrier is low density polyethylene, brand YBL-PEG2W, the manufacturer is Xiaxin Material;

[0039] Primary antioxidant: Antioxidant 245, bis[3-(1,1-dimethylethyl)-4-hydroxy-5-methylphenylpropionic acid]triethylene glycol, commercially available, the same commercial product was used in parallel experiments;

[0040] Secondary antioxidant: antioxidant 168, tris[2,4-di-tert-butylphenyl]phosphite, commercially available, the same commercial product was used in parallel experiments;

[0041] Formaldehyde absorbent: Commercially available. Parallel experiments used the same commercial product.

[0042] The preparation methods of the embodiments of the present invention and the comparative examples are as follows:

[0043] S1: Weigh each component according to the ratio, and mix each component in a high-speed mixer for 1 minute to 2 minutes to obtain a premix;

[0044] S2: adding the premix to a twin-screw extruder, and performing melt extrusion and granulation at 150° C.-220° C. to obtain a polyoxymethylene resin composition.

[0045] Among them, the barrel temperatures of the twin-screw extruder from the feeding port to the die are: 150℃, 170℃, 170℃, 180℃, 180℃, 190℃, 190℃, 200℃, 200℃, 220℃, the screw speed is 300 rpm, the feed rate is 100kg / h, and the vacuum degree is (-0.1)MPa.

[0046] The term "part(s)" in this specification means "part(s) by weight" unless otherwise specified.

[0047] <Performance Test Method>

[0048] The performance testing methods of the embodiments and comparative examples of the present invention are as follows:

[0049] Evaluation of friction coefficient and wear resistance: (1) Friction between plastics: a plastic multifunctional friction tester was used with a load of 3.88 N, a rotation speed of 200 rpm, and a test time of 120 min. The friction coefficient was recorded by the equipment and the wear of the material was tested. (2) Friction between plastics and metal (45# steel): a plastic multifunctional friction tester was used with a load of 10 N, a rotation speed of 500 rpm, and a test time of 120 min. The friction coefficient was recorded by the equipment and the wear of the material was tested.

[0050] Mold deposit: The sample was continuously injected into an injection molding machine at 230°C for 200 times, and the weight of the collected mold deposit was weighed to observe the mold deposit condition on the mold surface.

[0051] Table 1. Formulations of Examples 1-13

[0052]

[0053]

[0054] Table 2. Performance test results of Examples 1-13

[0055]

[0056]

[0057] Table 3. Comparative Examples 1-8 formulations

[0058]

[0059] Table 4. Performance test results of comparative examples 1-8

[0060]

[0061]

[0062] Compared with Example 1, the amount of ultra-high molecular weight silicone in Comparative Examples 1 and 2 exceeds the lower limit, resulting in an increase in the friction coefficient between plastics and the friction coefficient between plastic and metal in Comparative Example 1, and an increase in wear; the amount of ultra-high molecular weight silicone in Comparative Example 2 exceeds the upper limit, resulting in mold deposit in Comparative Example 2 and slipping during processing.

[0063] Compared with Example 1, Comparative Example 3 does not add polytetrafluoroethylene, resulting in an increase in the friction coefficient between plastics and the friction coefficient between plastic and metal in Comparative Example 3 and an increase in wear.

[0064] Compared with Example 1, in Comparative Examples 4 and 5, the amount of polytetrafluoroethylene used in Comparative Example 4 exceeds the lower limit, resulting in an increase in the friction coefficient between plastics and the friction coefficient between plastic and metal in Comparative Example 4 and an increase in wear; in Comparative Example 5, the amount of polytetrafluoroethylene used exceeds the upper limit, resulting in an increase in wear of Comparative Example 5, slight mold deposit, and poor processability.

[0065] Compared with Example 1, Comparative Example 6 does not add high molecular weight polyethylene glycol in the formula, resulting in increased wear of Comparative Example 6 and lack of processability.

[0066] Compared with Example 1, the amount of high molecular weight polyethylene glycol used in Comparative Examples 7 and 8 exceeded the range, resulting in increased wear and mold deposit in Comparative Examples 7 and 8, and lack of processability.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyoxymethylene resin composition, characterized in that By weight, it includes the following components: The number average molecular weight of the ultra-high molecular weight silicone is greater than 1 million; The number average molecular weight of the high molecular weight polyethylene glycol is 8000-22000.

2. The polyoxymethylene resin composition according to claim 1, characterized in that The polyoxymethylene resin is a copolymer polyoxymethylene resin and / or a homopolymer polyoxymethylene resin.

3. The polyoxymethylene resin composition according to claim 1, characterized in that The number average molecular weight of the ultra-high molecular weight silicone is 1-10 million.

4. The polyoxymethylene resin composition according to claim 1, characterized in that The molecular weight of the high molecular weight polyethylene glycol is 10000-20000.

5. The polyoxymethylene resin composition according to claim 1, characterized in that: Also includes 0-1 parts of auxiliary agents.

6. The polyoxymethylene resin composition according to claim 5, characterized in that: The auxiliary agent is one or more of an antioxidant, a formaldehyde absorber and a weathering agent.

7. A method for preparing the polyoxymethylene resin composition according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Weigh each component according to the ratio, and premix the components to obtain a premix; S2: adding the premix to an extruder, performing melt extrusion and granulation to obtain the polyoxymethylene resin composition.

8. Use of the polyoxymethylene resin composition according to any one of claims 1 to 6 in the preparation of mechanical gears, bearings and daily consumer products.

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