A polyoxymethylene composite material and its preparation method and application

Abstract

The present invention discloses a polyoxymethylene composite material comprising the following components, by weight: 100 parts of a copolymerized polyoxymethylene resin; 0.3-1 parts of a hydroxybenzophenone ultraviolet light absorber; 2-7 parts of polyethylene glycol; and 5-40 parts of glass fiber. The polyethylene glycol has a number average molecular weight range of 7,500-20,000. By adding polyethylene glycol of a specific molecular weight and content, and the hydroxybenzophenone ultraviolet light absorber, the present invention achieves the advantages of UV resistance and low odor while maintaining good mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a polyoxymethylene composite material and a preparation method and application thereof. Background Art

[0002] Polyoxymethylene (POM) is a highly crystalline linear thermoplastic polymer with excellent mechanical properties, wear resistance, self-lubrication, oil resistance, chemical resistance, creep resistance, low water absorption, and the ability to maintain its mechanical, chemical, and electrical properties over a wide temperature range. It is an engineering plastic with excellent comprehensive performance and is widely used in the automotive, electronics, and household appliance industries.

[0003] Copolymer polyoxymethylene is primarily composed of (-CH2-O-) chains, with small amounts of (-CH2CH2O-) or (-CH2CH2CH2CH2O-) chains, and terminal groups with methoxy ether or hydroxyethyl ether structures. This makes POM susceptible to chain scission under the influence of heat and oxygen during melt processing. This thermal decomposition is autocatalytic, releasing large amounts of formaldehyde and producing a strong odor. This strong, pungent odor has significantly limited the application of polyoxymethylene products in industries such as automotive.

[0004] The secondary methylene groups in polyoxymethylene (POM) molecules are less stable. Under the combined effects of ultraviolet light and oxygen, the molecular chains break, releasing gases such as formaldehyde, which in turn degrades mechanical properties and changes surface color. Therefore, for outdoor applications, the weather resistance of POM materials needs to be improved.

[0005] At the same time, when used in automotive products such as automotive glass sliders and window lift gears, higher mechanical properties are required. Therefore, mechanical properties are also one of the important considerations. Summary of the Invention

[0006] The object of the present invention is to provide a polyoxymethylene composite material having the advantages of ultraviolet resistance, low odor, good mechanical properties, etc., as well as a preparation method and application thereof.

[0007] The present invention is achieved through the following technical solutions:

[0008] A polyoxymethylene composite material, comprising the following components in parts by weight:

[0009] 100 parts of copolymerized polyoxymethylene resin;

[0010] 0.3-1 part of hydroxybenzophenone ultraviolet light absorber;

[0011] 2-7 parts of polyethylene glycol;

[0012] 5-40 parts of glass fiber;

[0013] The number average molecular weight of the polyethylene glycol is in the range of 7500-20000.

[0014] The test method for the number average molecular weight of polyethylene glycol can be: liquid chromatography to analyze low molecular weight polyethylene glycol, the chromatographic column adopts a C18 reverse phase chromatographic column; the mobile phase includes phases A and B, the two together are 100%, wherein phase A is a mixed solvent of methanol and tetrahydrofuran, and phase B is water, and phases A and B are mixed according to a volume ratio and then gradient eluted, and the elution procedure is: the initial proportion of phase A is 5%-15%, and the rest is phase B, and after a time length of 15-20 minutes, it gradually transitions to phase A accounting for 25-50%, and the rest is phase B, and the flow rate is 0.2-1 mL / min; the detector adopts an evaporative light scattering detector: the relative percentage content of each chromatographic peak is calculated by the area percentage method, and the number average molecular weight of polyethylene glycol is evaluated by the number and relative percentage content of the chromatographic peaks.

[0015] The copolymerized polyoxymethylene resin is a condensation product of dioxolane and trioxymethylene, wherein the dioxolane accounts for 1-3 wt % of the total weight of the copolymerized polyoxymethylene, and preferably, the dioxolane accounts for 1.8-2.3 wt % of the total weight of the copolymerized polyoxymethylene.

[0016] The content of dioxolane in the total weight of the copolymerized polyoxymethylene can be measured by hydrogen nuclear magnetic spectrum.

[0017] In the technical solution of the present invention, the melt index of the copolymerized polyoxymethylene resin can be in the range of 0.5-300 g / 10 min, and the test method is ASTM D1238.

[0018] The copolymerized polyoxymethylene can be a commercially available product or can be prepared in-house. The preparation method involves thoroughly mixing trioxymethylene with butyral (0.1%-0.35% by weight of the total trioxymethylene and dioxolane content), based on the weight percentage of the dioxolane copolymer units in the copolymerized polyoxymethylene resin. The mixture is then added to a prepolymer formed by mixing boron trifluoride (200-300 ppm) and dioxolane. The mixture is then polymerized in a kneader at 80-100°C for 2-3 hours. The resulting polymer powder is then mixed with melamine and extruded into pellets in a twin-screw extruder at 200-240°C. A triethylamine solution is then introduced into the middle of the extruder to produce polyoxymethylene pellets.

[0019] Preferably, the ethylene glycol content is 4-5.5 parts.

[0020] The hydroxybenzophenone ultraviolet light absorber is selected from at least one of 2-hydroxy-4-methoxybenzophenone, 2,2'-hydroxy-4-methoxybenzophenone, 2,4-hydroxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-acryloyloxyethoxybenzophenone, and (1,4-butanediyl)bis[oxy(2-hydroxy-4,1-phenylene)]bis[phenyl ketone].

[0021] Preferably, the hydroxybenzophenone ultraviolet light absorber is selected from at least one of 2,2'-hydroxy-4-methoxybenzophenone and 2,4-hydroxybenzophenone.

[0022] Preferably, the number average molecular weight of the polyethylene glycol is in the range of 9000-11000.

[0023] You can choose whether to add a specific content of 0-1 parts of antioxidant according to actual conditions.

[0024] The antioxidant can be specifically selected from 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,5-di-tert-butyl-4-hydroxybenzyldimethylamine, diethyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate, stearyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphate, 3,5-di-tert-butyl-4-hydroxyphenyl-3,5-distearyl-thiotriazolylamine, 2,6-di-tert-butyl-4-hydroxymethylphenol, 2,4-di-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butyl glycerol allyl ether)-1,3,5-triazine, N,N'-hexamethylene Bis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid), N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3,5-dimethyl-4-hydroxyphenyl)propionate], triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], 2,2'-thiodiethyl-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, etc.

[0025] It is also possible to consider adding 0-40 parts of filler, which may be a mineral filler or the like.

[0026] The preparation method of the polyoxymethylene composite material of the present invention comprises the following steps: uniformly mixing all components except glass fiber according to a proportion, extruding and granulating the components through a twin-screw extruder (temperature range: 180-200°C, speed: 300-400 rpm), and feeding the glass fiber sideways to obtain the polyoxymethylene composite material.

[0027] The polyoxymethylene composite material of the present invention is used for preparing automobile glass sliders, window lift gears and the like.

[0028] The present invention has the following beneficial effects:

[0029] The present invention introduces polyethylene glycol and hydroxybenzophenone ultraviolet light absorbers of specific content and number average molecular weight to improve the defect of cyclic ether copolymer polyoxymethylene, which is easy to decompose and causes excessive odor, and has excellent ultraviolet resistance. At the same time, due to the relatively high molecular weight of polyethylene glycol, the polyoxymethylene composite material can maintain high mechanical properties. Implementation Method

[0030] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0031] The raw materials used in the present invention come from the following sources:

[0032] The following polyoxymethylene copolymer resins are prepared by thoroughly mixing trioxymethylene with butyral (0.15-0.20 wt% of the total trioxymethylene and dioxolane content), based on the weight percentage of dioxolane copolymer units in the copolymerized polyoxymethylene resin. The mixture is then added to a prepolymer formed by mixing boron trifluoride (200 ppm) and dioxolane as a catalyst. The mixture is then polymerized in a kneader at 80-100°C for 2-3 hours. The resulting polymer powder is then mixed with melamine and extruded into pellets in a twin-screw extruder. A triethylamine aqueous solution is then introduced into the extruder to produce the polyoxymethylene raw material. The molecular weights of the following copolymerized polyoxymethylene resins are similar. The extrusion process is as follows: zone 1 temperature 200-210°C, zone 2 temperature 200-210°C, zone 3 temperature 210-220°C, zone 4 temperature 210-220°C, zone 5 temperature 220-230°C, zone 6 temperature 220-230°C, zone 7 temperature 220-230°C, zone 8 temperature 220-230°C, zone 9 temperature 230-240°C; main engine speed 300-400 rpm.

[0033] Copolymer polyoxymethylene resin A: polycondensate of trioxymethylene and dioxolane, wherein dioxolane accounts for 1 wt% of the total weight of the copolymer polyoxymethylene, and is prepared in-house;

[0034] Copolymer polyoxymethylene resin B: polycondensate of trioxymethylene and dioxolane, dioxolane accounts for 1.8wt% of the total weight of the copolymer polyoxymethylene, homemade;

[0035] Copolymer polyoxymethylene resin C: polycondensate of trioxymethylene and dioxolane, dioxolane accounts for 2.3wt% of the total weight of the copolymer polyoxymethylene, homemade;

[0036] Copolymer polyoxymethylene resin D: polycondensate of trioxymethylene and dioxolane, dioxolane accounts for 3wt% of the total weight of the copolymer polyoxymethylene, homemade;

[0037] Copolymer polyoxymethylene resin E: polycondensate of trioxymethylene and dioxolane, wherein dioxolane accounts for 5 wt% of the total weight of the copolymer polyoxymethylene, and is self-made;

[0038] Homopolymer polyoxymethylene resin: brand POM 500P, homopolymer POM grade, melt index 14g / 10min, DuPont, USA;

[0039] Polyethylene glycol A: number average molecular weight of about 8000, Donol PEG-8000, Shanghai Dongda Chemical Co., Ltd.

[0040] Polyethylene glycol B: number average molecular weight of about 10,000, Donol PEG10000, Shanghai Dongda Chemical Co., Ltd.

[0041] Polyethylene glycol C: number average molecular weight of about 20,000, Donol PEG20000, Shanghai Dongda Chemical Co., Ltd.

[0042] Polyethylene glycol D: number average molecular weight of about 6000, Donol PEG6000, Shanghai Dongda Chemical Co., Ltd.;

[0043] Polyethylene glycol E: number average molecular weight of about 4000, Donol PEG4000, Shanghai Dongda Chemical Co., Ltd.;

[0044] UV absorber A: 2-hydroxy-4-octyloxybenzophenone, Cyasorb UV-531, Cytec Corporation, USA;

[0045] UV absorber B: 2-hydroxy-4-methoxybenzophenone, Cyasorb UV-9, Cytec Corporation, USA;

[0046] UV absorber C: 2,2'-hydroxy-4-methoxybenzophenone, Cyasorb UV-24, Cytec Corporation, USA;

[0047] UV absorber D: 2,4-hydroxybenzophenone, UV BP-1, Qingdao Deda Zhicheng Chemical Co., Ltd.

[0048] UV absorber E: 2-hydroxy-4-dodecyloxybenzophenone, Chimassorb 125, BASF, Germany;

[0049] UV absorber F: 2-(2'-hydroxy-3',5'-bis(a,a-dimethylbenzyl)phenyl)benzotriazole, UV-234, Qingdao Deda Zhicheng Chemical Co., Ltd.

[0050] UV absorber G: 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-octyloxyphenol, UV-1164, Qingdao Deda Zhicheng Chemical Co., Ltd.

[0051] Glass fiber: chopped glass fiber, ECS10-3.0-T445, glass fiber diameter 10 μm, Taishan Glass Fiber Co., Ltd.

[0052] Antioxidant: Irganox 245 / Irganox 1098, mixed in a weight ratio of 2:1, purchased from BASF.

[0053] Preparation method of polyoxymethylene composite material of embodiment and comparative example: according to the ratio, each component is mixed uniformly, and extruded into granules by a twin-screw extruder at a temperature range of 180-200° C. and a rotation speed of 300-400 rpm to obtain a polyoxymethylene composition.

[0054] Various test methods:

[0055] (1) UV resistance test: The sample was injection molded into a square plate and tested according to the Volkswagen PV3929-2008 standard. The blackboard temperature was 90°C, the sample chamber temperature was 50°C, the relative humidity was 20±10%, and the irradiation intensity was 75W / m 2 , UV wavelength range 300-400nm. Irradiation time 1200h, total irradiation dose 300MJ / m 2 The test equipment is ATLAS CI4000, USA. The color difference change value is calculated by the following formula:

[0056]

[0057] L1, a1, b1: test values ​​before xenon lamp aging;

[0058] L2, a2, b2: test values ​​after xenon lamp aging;

[0059] The color difference test equipment is produced by X-Rite, USA, model number is Color-Eye 7000A.

[0060] (2) Odor level test: The odor level test is conducted according to the Volkswagen PV3900 standard. The specific process is as follows: 20g of the pellets extruded from the twin-screw extruder are sampled and placed in a 1L glass bottle specially designed for odor testing. The bottle is sealed and placed in an 80℃ oven. After 2 hours, the odor is taken out and evaluated according to the following standards. The odor is evaluated by 5 professional odor testers, and the average value is calculated.

[0061] Rating level Judging Criteria 1 Odorless 2 There is an odor, but it is not disturbing 3 There is a noticeable smell, but no disturbing smell 4 There is a disturbing smell 5 Has a strong, disturbing odor 6 There is an unbearable smell

[0062] (3) Tensile strength: The test was carried out in accordance with ISO527-2019 standard, the specimen size was 170 mm × 10 mm × 4 mm, the test speed was 10 mm / min, and the test equipment was an electronic tensile testing machine from Zwick, Germany.

[0063] Table 1: Weight parts of each component of the polyoxymethylene composite material of Examples 1-5 and test results

[0064] Example 1 Example 2 Example 3 Example 4 Example 5 Types of copolymer polyoxymethylene resins A B C D A Copolymer polyoxymethylene resin content 100 100 100 100 100 UV absorber A 0.5 0.5 0.5 0.5 0.5 fiberglass 30 30 30 30 30 Polyethylene glycol A 4 4 4 4 2 antioxidants 0.1 0.1 0.1 0.1 0.1 ΔE 2.48 2.39 2.32 2.42 2.68 Odor level 3.6 3.5 3.4 3.6 3.9 Tensile strength, MPa 124.5 123.6 119.5 117.8 116.5

[0065] As can be seen from Examples 1-4, the dioxolane preferably accounts for 1.8-2.3 wt % of the total weight of the copolymerized polyoxymethylene.

[0066] Table 2: Weight of each component of the polyoxymethylene composite material of Examples 6-9 and test results

[0067] Example 6 Example 7 Example 8 Example 9 Copolymer polyoxymethylene resin A 100 100 100 100 UV absorber A 0.5 0.5 0.3 1 fiberglass 30 30 5 40 Polyethylene glycol A 5.5 7 4 4 antioxidants 0.1 0.1 0.1 0.1 ΔE 2.62 2.92 2.99 1.65 Odor level 3.2 3.0 3.1 3.6 Tensile strength, MPa 125.4 123.6 64.5 130.9

[0068] It can be seen from Examples 5 / 1 / 6 / 7 that the preferred polyethylene glycol content is 4-5.5 parts.

[0069] Table 3: Weight parts of each component of the polyoxymethylene composite material of Examples 10-15 and test results

[0070] Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Copolymer polyoxymethylene resin A 100 100 100 100 100 100 Types of UV absorbers B C D E A A UV absorber content 0.5 0.5 0.5 0.5 0.5 0.5 fiberglass 30 30 30 30 30 30 Polyethylene glycol A 4 4 4 4 Polyethylene glycol B 4 Polyethylene glycol C 4 antioxidants 0.1 0.1 0.1 0.1 0.1 0.1 ΔE 2.55 2.12 2.35 2.52 2.72 2.81 Odor level 3.5 3.4 3.2 3.5 3.7 3.8 Tensile strength, MPa 123.5 124.1 122.2 120.9 129.6 127.5

[0071] It can be seen from Examples 1 / 10-13 that the preferred UV absorber has better UV resistance and less odor.

[0072] It can be seen from Examples 1 / 14 / 15 that the tensile strength is higher when the number average molecular weight of polyethylene glycol is preferably 9000-11000.

[0073] It can be seen from the above examples that the polyoxymethylene composite material of the present invention has a ΔE less than 3.1 and an odor level ≤3.9.

[0074] Table 4: Weight parts of each component of the polyoxymethylene composite materials of Comparative Examples 1-6 and test results

[0075] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Copolymer polyoxymethylene resin A 100 100 100 100 Copolymer polyoxymethylene resin E 100 Homopolymer polyoxymethylene resin 100 Types of UV absorbers F G A A A A UV absorber content 0.5 0.5 0.5 0.5 0.5 0.5 fiberglass 30 30 30 30 30 30 Polyethylene glycol A 4 4 4 4 1 9 antioxidants 0.1 0.1 0.1 0.1 0.1 0.1 ΔE 4.65 4.12 4.16 4.86 3.32 3.86 Odor level 4.0 4.1 4.0 3.6 4.1 3.8 Tensile strength, MPa 116.5 114.2 108.3 129.6 114.6 113.5

[0076] It can be seen from Comparative Examples 1 / 2 that other types of ultraviolet absorbers in the technical solution of the present invention have poor anti-ultraviolet performance and a strong odor.

[0077] It can be seen from Comparative Example 3 that if the comonomer content in the copolymerized polyoxymethylene resin is too high, the UV resistance is poor.

[0078] It can be seen from Comparative Example 4 that the homopolyoxymethylene resin cannot achieve the technical effect of the present invention.

[0079] It can be seen from Comparative Examples 5 and 6 that if the polyethylene glycol content is too low or too high, the UV resistance and odor resistance are insufficient, while when the polyethylene glycol content is too high, the tensile strength is significantly reduced.

[0080] Table 6: Weight parts of each component of the polyoxymethylene composite material of Comparative Examples 7-8 and test results

[0081] Comparative Example 7 Comparative Example 8 Copolymer polyoxymethylene resin A 100 100 Types of UV absorbers A A UV absorber content 0.3 0.3 fiberglass 5 5 Polyethylene glycol D 4 Polyethylene glycol E 4 antioxidants 0.1 0.1 ΔE 2.89 3.04 Odor level 3.0 2.9 Tensile strength, MPa 57.5 55.1

[0082] It can be seen from Comparative Examples 7 / 8 that if the number average molecular weight of polyethylene glycol is too low, the tensile strength will be significantly reduced.

Claims

1. A polyoxymethylene composite material, characterized in that: Calculated by weight, it includes the following components: 100 parts of copolymerized polyoxymethylene resin; 0.3-1 part of hydroxybenzophenone ultraviolet light absorber; 4-5.5 parts of polyethylene glycol; 5-40 parts of glass fiber; The number average molecular weight of the polyethylene glycol is in the range of 7500-20000; The copolymerized polyoxymethylene resin is a condensation product of dioxolane and trioxymethylene, wherein the dioxolane accounts for 1.8-2.3 wt% of the total weight of the copolymerized polyoxymethylene.

2. The polyoxymethylene composite material according to claim 1, characterized in that The hydroxybenzophenone ultraviolet light absorber is selected from at least one of 2-hydroxy-4-methoxybenzophenone, 2,2'-hydroxy-4-methoxybenzophenone, 2,4-hydroxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-acryloyloxyethoxybenzophenone, and (1,4-butanediyl)bis[oxy(2-hydroxy-4,1-phenylene)]bis[phenyl ketone].

3. The polyoxymethylene composite material according to claim 2, characterized in that The hydroxybenzophenone ultraviolet light absorber is selected from at least one of 2,2'-hydroxy-4-methoxybenzophenone and 2,4-hydroxybenzophenone.

4. The polyoxymethylene composite material according to claim 1, characterized in that The number average molecular weight of the polyethylene glycol is in the range of 9000-11000.

5. The polyoxymethylene composite material according to claim 1, characterized in that: By weight, 0-1 part of antioxidant is also included.

6. The method for preparing the polyoxymethylene composite material according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: uniformly mixing all components except glass fiber according to a proportion, extruding and granulating through a twin-screw extruder, and feeding the glass fiber sideways to obtain a polyoxymethylene composite material.

7. Use of the polyoxymethylene composite material according to any one of claims 1 to 5, characterized in that: Used to prepare automotive glass sliders and window lift gears.