Liquid crystalline polymer material, process for its preparation and use thereof

Abstract

The present application relates to a kind of liquid crystal polymer materials and its preparation method and application.The liquid crystal polymer material includes the following components: liquid crystal polymer, composite ultraviolet light absorber, light shielding agent and glycidyl methacrylate polymer.The present application is by the cooperation of light shielding agent, composite light ultraviolet absorber and glycidyl methacrylate polymer, the obvious promotion of the ultraviolet yellowing resistance of liquid crystal polymer material is realized, so that liquid crystal polymer material can be used in server, notebook computer fan, e-sports equipment cooling fan or electronic connector and the like field.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a liquid crystal polymer material, its preparation method, and its application. Background Technology

[0002] Liquid crystal polymers (LCPs) possess excellent high-frequency dielectric properties, processing fluidity, high heat resistance, dimensional stability, and superior mechanical strength, making them widely used in servers, laptop fans, gaming device cooling fans, and electronic connectors. With industry development, simple black is no longer sufficient to meet product color requirements, necessitating various color matching processes. However, as fully aromatic polymers, LCPs have a high content of benzene or naphthalene rings in their molecular structure. LCPs exhibit high sensitivity to ultraviolet light, displaying a very pronounced UV yellowing characteristic. This is because under prolonged UV irradiation, thermal-Fries or photo-Fries rearrangements readily occur, forming π-π conjugated double bonds, generating chromophores, and causing the production of yellow substances. When LCP products come into contact with sunlight, the ultraviolet rays in sunlight cause the LCPs to yellow, resulting in a change in product color.

[0003] To ensure that the product's color remains unchanged when exposed to sunlight, very strict requirements are placed on the weather resistance of liquid crystal materials, especially their resistance to ultraviolet aging.

[0004] There are currently few reports on improving the UV resistance of liquid crystal materials, and there is an urgent need to develop technologies to solve the problem of poor UV resistance of liquid crystal materials. Summary of the Invention

[0005] The primary objective of this invention is to overcome the technical problems existing in the prior art and to provide a liquid crystal polymer material.

[0006] A further object of the present invention is to provide a method for preparing the above-mentioned liquid crystal polymer material.

[0007] A further object of the present invention is to provide the application of the above-mentioned liquid crystal polymer material in the manufacture of components for electronic products.

[0008] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0009] A liquid crystal polymer material comprises the following components in parts by weight:

[0010]

[0011] The composite ultraviolet light absorber comprises a first ultraviolet light absorber and a second ultraviolet light absorber in a mass ratio of 1:(0.4-1.2);

[0012] The first ultraviolet light absorber is a triazine ultraviolet light absorber, and the second ultraviolet light absorber is at least one of benzotriazole ultraviolet light absorbers, benzophenone ultraviolet light absorbers, or benzoxazine ultraviolet light absorbers.

[0013] This invention adds a light-shielding agent to a liquid crystal polymer material, which acts to block and reflect ultraviolet light, thereby improving the resistance of the liquid crystal polymer material to ultraviolet yellowing.

[0014] The inventors of this invention discovered through research that by selecting specific ultraviolet absorbers and incorporating them into liquid crystal polymer materials, the materials can effectively cover the UV-A and UV-B bands of ultraviolet light, absorb a wide range of ultraviolet light, and thus improve the yellowing resistance of the liquid crystal polymer materials.

[0015] However, simply adding a composite UV absorber directly to the liquid crystal polymer material does not significantly improve its resistance to yellowing. The inventors further discovered that adding a certain amount of glycidyl methacrylate polymer not only provides excellent thermal stability and prevents degradation at the high processing temperatures of the liquid crystal polymer material, but also utilizes the high polarity of the epoxy groups in the glycidyl methacrylate polymer to selectively distribute the composite UV absorber within it. Furthermore, by leveraging the high crystallinity of the liquid crystal polymer and its compatibility differences with the glycidyl methacrylate polymer, the composite UV absorber is induced to migrate and approach the material's surface, further enhancing the liquid crystal polymer material's resistance to UV yellowing.

[0016] In this invention, a liquid crystal polymer is used as the main resin; preferably, the liquid crystal polymer is a liquid crystal polyester; preferably, the liquid crystal polymer accounts for more than 38 wt% of the liquid crystal polymer material.

[0017] Liquid crystal polymers commonly used in this field can be used in this invention. For example, liquid crystal polymers formed by polymerizing aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids with one or more compounds, such as aromatic diols or aromatic hydroxyamines; or liquid crystal polymers formed by polymerizing different aromatic hydroxycarboxylic acids; or liquid crystal polymers formed by polymerizing aromatic dicarboxylic acids with aromatic diols, aromatic hydroxyamines, or at least one compound. Liquid crystal polymers can be either homemade or commercially available.

[0018] Preferably, the melting point (Tm) of the liquid crystal polymer is 260–330°C.

[0019] The melting point of liquid crystal polymers can be determined using a differential scanning calorimeter. The testing procedure is as follows: the heating rate is 20℃ / min, the temperature is raised to 30℃ above the melting point and held for 5 minutes to eliminate thermal history, and the melting point Tm is obtained from the curve of the second heating.

[0020] Optionally, the intrinsic viscosity of the liquid crystal polymer is 3.0 to 7.0 dL / g (e.g., 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 or 7.0 dL / g); the intrinsic viscosity can be measured using a Uss viscometer at 80°C, and the solvent is pentafluorophenol.

[0021] In this invention, the mass ratio of the first ultraviolet absorber and the second ultraviolet absorber can specifically be 1:0.4, 1:0.5, 1:0.8, 1:1 or 1:1.2.

[0022] Preferably, the triazine-based ultraviolet absorber is at least one selected from 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxyphenol, 2,4-bis(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(2,4-dihydroxyphenyl)-6-phenyl-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1,3,5-triazine, and 2,4,6-tris(2,4-dihydroxyphenyl)-1,3,5-triazine.

[0023] Preferably, the benzotriazole ultraviolet absorber is at least one of 2,2'-methylenebis(4-tert-octyl-6-benzotriazole phenol), 2-(3'-tert-butyl-2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-[2-hydroxy-5-(1,1,3,3-tetramethylbutyl)phenyl]benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, etc.

[0024] Preferably, the benzophenone-based ultraviolet absorber is at least one of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone.

[0025] Preferably, the benzoxazine ultraviolet absorber includes, but is not limited to, 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazine-4-one.

[0026] Preferably, the light-shielding agent is at least one of titanium dioxide, zinc oxide, or silicon dioxide.

[0027] More preferably, the light-shielding agent is titanium dioxide and silicon dioxide compounded in a mass ratio of 1:0.2 to 0.4; the average particle size of the titanium dioxide is 100 to 400 nm; and the average particle size of the silicon dioxide is 15 to 50 nm.

[0028] Titanium dioxide can typically only be produced at the submicron level. By using this compounded light-shielding agent, smaller silica particles can fill the gaps between the titanium dioxide particles, thereby achieving a better light-shielding effect and improving the UV resistance of the liquid crystal polymer material.

[0029] In this invention, the average particle size of the light-shielding agent can be measured by a particle size analyzer.

[0030] More preferably, the titanium dioxide has a rutile crystal form.

[0031] Preferably, the glycidyl methacrylate polymer is at least one of ethylene-butyl acrylate-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate copolymer, or ethylene-methyl acrylate-glycidyl methacrylate copolymer.

[0032] More preferably, the glycidyl methacrylate polymer is an ethylene-butyl acrylate-glycidyl methacrylate copolymer.

[0033] More preferably, the ethylene-butyl acrylate-glycidyl methacrylate copolymer contains 75-85 wt% ethylene units, 5-10 wt% butyl acrylate units, and 6-15 wt% glycidyl methacrylate units.

[0034] More preferably, the ethylene-glycidyl methacrylate copolymer contains 85-95 wt% ethylene units and 5-15 wt% glycidyl methacrylate units.

[0035] More preferably, the ethylene-methyl acrylate-glycidyl methacrylate copolymer contains 75-85 wt% ethylene units, 5-10 wt% methyl acrylate units, and 6-15 wt% glycidyl methacrylate units.

[0036] Preferably, the melt index of the glycidyl methacrylate polymer measured at 190°C and 2.16 kg is 3 to 10 g / min, and the melt index is determined according to ASTM D-1238-2010 standard.

[0037] Preferably, the mass ratio of the composite ultraviolet absorber to the glycidyl methacrylate polymer is (8-11):(2-5).

[0038] More preferably, the mass ratio of the composite ultraviolet absorber to the glycidyl methacrylate polymer is (10-11):(3-5). Within this mass ratio range, the liquid crystal polymer material exhibits better resistance to ultraviolet yellowing.

[0039] Preferably, the liquid crystal polymer material further includes 10 to 30 parts of glass fiber.

[0040] Preferably, the liquid crystal polymer material further includes 0.2 to 1 part of other additives.

[0041] Optionally, the other additives include, but are not limited to, lubricants.

[0042] Optionally, the lubricant includes, but is not limited to, linear low-density polyethylene.

[0043] The preparation method of the above-mentioned liquid crystal polymer material includes the following steps: mixing the components, melt extruding, and granulating to obtain the liquid crystal polymer material.

[0044] Preferably, the screw speed of the twin-screw extruder in the melt extrusion is 300-500 rpm, and the length-to-diameter ratio of the screw is 35-50:1.

[0045] The application of the aforementioned liquid crystal polymer material in the manufacture of electronic product components is also within the scope of protection of this invention.

[0046] Preferably, the electronic product is a server, a laptop computer, a gaming device, or an electronic connector.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] This invention achieves a significant improvement in the UV resistance of liquid crystal polymer materials by combining light-shielding agents, composite UV absorbers, and glycidyl methacrylate polymers, enabling the liquid crystal polymer materials to be used in servers, laptop fans, gaming device cooling fans, or electronic connectors, among other fields. Detailed Implementation

[0049] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0050] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0051] Liquid crystal polymer 1#: self-made, the preparation process is as follows: p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA) were added to a reaction vessel containing acetic anhydride acylation solution at a molar ratio of 73:27. The reactor was then placed in a 240°C salt bath for reflux for 2 hours. After the byproduct acetic acid stopped distilling, the temperature of the reactor was increased to 300°C at a heating rate of 5°C / min. Acetic acid and unreacted small molecules of raw materials were discharged from the distillation column. The internal pressure of the reaction vessel was then reduced to below 10 kPa and maintained at this pressure until the power of the agitator reached 7 kW. The material was then discharged and granulated to obtain liquid crystal polymer 1#.

[0052] Liquid crystal polymer 2#: self-made, the preparation process differs from that of liquid crystal polymer 1# in that: p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA) are added in a reaction vessel containing an acetic anhydride acylation dose at a molar ratio of 70:30.

[0053] Liquid crystal polymer #3: Purchased from Polyplastics Corporation of Japan, brand name Vectra A950, melting point 280℃.

[0054] Liquid crystal polymer #4: Purchased from Polyplastics Corporation of Japan, brand name Vectra C950, melting point 320℃.

[0055] First UV absorber: Triazine UV absorber, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy-phenol, commercially available;

[0056] Second UV absorber #1: Benzotriazole UV absorber, 2,2'-methylenebis(4-tert-octyl-6-benzotriazole phenol), commercially available;

[0057] Second UV absorber #2: Benzooxazine UV absorber, 2,2'-(1,4-phenylene)bis-4H-3,1-benzooxazine-4-one, commercially available;

[0058] Second UV absorber #3: Benzophenone-based UV absorber, 2-hydroxy-4-n-octyloxybenzophenone, commercially available;

[0059] Other UV absorbers #1: Hindered amine UV absorber, 1,5,8,12-tetra[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazin-2-yl]-1,5,8,12-tetraazadodecane, commercially available;

[0060] Composite UV absorber 1#: It is obtained by mixing the first UV absorber and the second UV absorber 1# in a mass ratio of 1:1.

[0061] Composite UV absorber 2#: It is obtained by mixing the first UV absorber and the second UV absorber 2# in a mass ratio of 1:1.

[0062] Composite UV absorber 3#: It is obtained by mixing the first UV absorber and the second UV absorber 3# in a mass ratio of 1:1.

[0063] Composite UV absorber 4#: It is obtained by mixing the first UV absorber and the second UV absorber 1# in a mass ratio of 1:0.4.

[0064] Composite UV absorber 5#: It is obtained by mixing the first UV absorber and other UV absorbers 1# in a mass ratio of 1:1.

[0065] Composite UV absorber 6#: It is obtained by mixing other UV absorbers 1# and second UV absorber 1# in a mass ratio of 1:1.

[0066] Light shielding agent #1: Titanium dioxide, average particle size 300nm, R-105, Chemours Titanium Dioxide Technology;

[0067] Light shielding agent #2: It is obtained by mixing titanium dioxide and silicon dioxide in a mass ratio of 1:0.2; Titanium dioxide: average particle size is about 300nm, R-105, Chemours Titanium Dioxide Technology; Silicon dioxide: average particle size is 30nm, DK-SiO2-30, Beijing Deco Island Gold Technology Co., Ltd.

[0068] Glycidyl methacrylate polymer 1#: Ethylene-butyl acrylate-glycidyl methacrylate copolymer, PTW, DuPont, USA;

[0069] Glycidyl methacrylate polymer 2#: Ethylene-glycidyl methacrylate copolymer, BF-E, Sumitomo, Japan;

[0070] Glycidyl methacrylate polymer 3#: Ethylene-methyl acrylate-glycidyl methacrylate copolymer, AX8900, Arkema, France;

[0071] Ethylene bis-stearamide: P-200, Guangzhou Xihuan Chemical Technology Co., Ltd.;

[0072] Fiberglass: ECS10-03-584A, China Jushi Co., Ltd.;

[0073] Other additives #1: Lubricant LLDPE LL6101RQ, ExxonMobil;

[0074] Unless otherwise specified, all components (e.g., other additives 1#, etc.) used in each parallel embodiment and comparative example are the same commercially available products.

[0075] The liquid crystal polymer materials provided in the embodiments and comparative examples of this invention were subjected to performance testing according to the following test methods:

[0076] 1. UV resistance yellowing test: Each liquid crystal polymer material is injection molded into a standard test plate and tested according to ISO48922 cycle 2 conditions. After 144 hours of irradiation, the color difference of the test plate is tested. Each sample is tested three times and the average value of the three color differences is taken.

[0077] 2. Mechanical property testing: Tensile strength test: Tested under ISO 527-1 / -2 conditions at a tensile speed of 10 mm / min, and the average of 5 test results was taken. Flexural modulus test: Tested under ISO 178 conditions at a bending speed of 2 mm / min, and the average of 5 test results was taken.

[0078] The preparation process of the liquid crystal polymer materials in the embodiments and comparative examples of the present invention is as follows: Each component is weighed according to the formula. Components other than glass fiber (if present) and light-shielding agent are added through the main feed inlet of a twin-screw extruder. Glass fiber (if present) and light-shielding agent are added through the side feed inlet of the twin-screw extruder. The mixture is melt-extruded at a temperature 20°C higher than the melting point of the liquid crystal polymer. After cooling and granulation, the liquid crystal polymer material is obtained. The screw speed of the twin-screw extruder is 400 rpm, and the screw length-to-diameter ratio is 40:1.

[0079] Examples 1-14

[0080] Examples 1-14 provide a series of liquid crystal polymer materials, the formulations of which are shown in Tables 1 and 2.

[0081] Table 1. Formulations (parts by weight) for Examples 1-7

[0082]

[0083] Table 2. Formulations (parts by weight) for Examples 8-14

[0084]

[0085]

[0086] Comparative Examples 1-8

[0087] Comparative Examples 1-8 provide a series of liquid crystal polymer materials, the formulations of which are shown in Table 3.

[0088] Table 3 shows the formulations (parts by weight) for Comparative Examples 1–8.

[0089]

[0090] The performance of the liquid crystal polymer materials of each embodiment and comparative example was determined according to the test methods mentioned above, and the test results are shown in Table 4.

[0091] Table 4. Performance test results of the liquid crystal polymer materials in each embodiment and comparative example.

[0092]

[0093] As can be seen from Table 4:

[0094] The ΔE values ​​of the liquid crystal polymer materials in Examples 1-14 for UV yellowing resistance tests are all less than 8.8, indicating that the liquid crystal polymer materials of the present invention have good UV yellowing resistance. Furthermore, the liquid crystal polymer materials of the present invention also maintain good tensile strength (above 116 MPa) and flexural modulus (above 13100 MPa).

[0095] The composite UV absorbers used in Comparative Examples 1 and 2 were unsuitable. In Comparative Examples 3 and 4, a single UV absorber was added, resulting in poor UV yellowing resistance of the liquid crystal polymer material. In Comparative Example 5, no light-shielding agent was added, resulting in poor UV yellowing resistance of the liquid crystal polymer material. In Comparative Example 6, no glycidyl methacrylate polymer was added, resulting in poor UV yellowing resistance of the liquid crystal polymer material. In Comparative Example 7, the amount of glycidyl methacrylate polymer added was too high, leading to excessively high melt viscosity of the liquid crystal polymer material. This prevented the composite UV absorber from dispersing well and reaching the material surface, resulting in poor UV yellowing resistance. In Comparative Example 8, commonly used ethylene bis-stearamide with dispersing properties was added, but the improvement in UV yellowing resistance of the liquid crystal polymer material was not significant.

[0096] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A liquid crystalline polymer material, characterized in that, The components include the following parts by weight: 35-52 parts of liquid crystal polymer, 4-15 parts of composite ultraviolet light absorber 10-31 parts of light shielding agent 2-5 parts of glycidyl methacrylate polymer; The composite ultraviolet light absorber comprises a first ultraviolet light absorber and a second ultraviolet light absorber in a mass ratio of 1:(0.4~1.2); The first ultraviolet light absorber is 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol, and the second ultraviolet light absorber is at least one of benzotriazole ultraviolet light absorbers, benzophenone ultraviolet light absorbers, or benzoxazine ultraviolet light absorbers. The liquid crystal polymer is a liquid crystal polymer formed by polymerizing aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids with at least one compound of aromatic diol or aromatic hydroxyamine, or a liquid crystal polymer formed by polymerizing different aromatic hydroxycarboxylic acids, or a liquid crystal polymer formed by polymerizing aromatic dicarboxylic acids with aromatic diol or aromatic hydroxyamine. The intrinsic viscosity of the liquid crystal polymer is 3.0~7.0 dL / g; The glycidyl methacrylate polymer is at least one of ethylene-butyl acrylate-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate copolymer, or ethylene-methyl acrylate-glycidyl methacrylate copolymer. The melt index of the glycidyl methacrylate polymer was measured at 190°C and 2.16 kg, and was 3~10 g / min. The melt index was determined according to ASTM D-1238-2010 standard.

2. The liquid crystalline polymer material of claim 1, wherein The melting point of the liquid crystal polymer is 270~330℃.

3. The liquid crystalline polymer material of claim 1, wherein, The light-shielding agent is at least one of titanium dioxide, zinc oxide, or silicon dioxide.

4. The liquid crystalline polymer material of claim 3, wherein The light-shielding agent is a mixture of titanium dioxide and silicon dioxide in a mass ratio of 1:0.2~0.4; the average particle size of the titanium dioxide is 100~400nm; and the average particle size of the silicon dioxide is 15~50nm.

5. The liquid crystalline polymer material of claim 1, wherein The mass ratio of the composite ultraviolet absorber to the glycidyl methacrylate polymer is (8~11):(2~5).

6. The liquid crystalline polymer material of claim 1, wherein, The liquid crystal polymer material also includes 10 to 30 parts of glass fiber.

7. The liquid crystalline polymer material of claim 1, wherein The liquid crystal polymer material also includes 0.2 to 1 part of other additives.

8. A method for preparing the liquid crystal polymer material according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the components, melt extruding, and granulating to obtain the liquid crystal polymer material.

9. The use of the liquid crystal polymer material according to any one of claims 1 to 7 in the manufacture of components for electronic products.

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