Liquid crystal polymer material as well as preparation method and application thereof

Abstract

The invention relates to a liquid crystal polymer material as well as a preparation method and application thereof. The liquid crystal polymer material comprises the following components: a liquid crystal polymer, a composite ultraviolet absorber, a light screener and a glycidyl methacrylate polymer. Through cooperation of the light screening agent, the composite light ultraviolet absorbent and the glycidyl methacrylate polymer, the ultraviolet yellowing resistance of the liquid crystal polymer material is obviously improved, so that the liquid crystal polymer material can be applied to the fields of servers, notebook computer fans, electronic sports equipment cooling fans or electronic connectors and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically, to a liquid crystal polymer material and a preparation method and application thereof. Background Art

[0002] Liquid crystal polymer (LCP) has excellent high-frequency dielectric properties, processing fluidity and high heat resistance, dimensional stability and excellent mechanical strength. It has a wide range of applications in servers, laptop fans, e-sports equipment cooling fans or electronic connectors. With the development of the industry, pure black can no longer meet the color requirements of products, and various color matching treatments are required for materials. However, as a fully aromatic polymer, liquid crystal polymer has a high content of benzene rings or naphthalene rings in its molecular structure. Liquid crystal polymers are highly sensitive to ultraviolet light and show very obvious ultraviolet yellowing characteristics. This is because under long-term ultraviolet light irradiation conditions, thermal-Fries or photo-Fries Fries rearrangement is very likely to occur, forming π-π conjugated double bonds, generating chromophores, and causing yellow substances to be produced. When liquid crystal polymer products come into contact with sunlight, because the sunlight contains ultraviolet rays, the ultraviolet rays will cause the liquid crystal polymer to turn yellow and cause the product color to change.

[0003] In order to ensure that the color of the product remains unchanged when exposed to sunlight, very strict requirements are placed on the weather resistance of liquid crystal materials, especially anti-ultraviolet aging.

[0004] Currently, there are few reports on improving the UV yellowing resistance of liquid crystal materials, and there is an urgent need to develop technology to solve the problem of poor UV yellowing resistance of liquid crystal materials. Summary of the invention

[0005] The primary purpose of the present invention is to overcome the technical problems existing in the above-mentioned prior art and provide a liquid crystal polymer material.

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

[0007] A further object of the present invention is to provide the use of the above liquid crystal polymer material in preparing components of electronic products.

[0008] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0009] A liquid crystal polymer material, comprising 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 a benzotriazole ultraviolet light absorber, a benzophenone ultraviolet light absorber or a benzoxazine ultraviolet light absorber.

[0013] The present invention adds a light shielding agent into the liquid crystal polymer material, which plays the role of shielding and reflecting ultraviolet light, and can improve the ultraviolet yellowing resistance of the liquid crystal polymer material.

[0014] The inventors of the present invention have found through research that by selecting a specific ultraviolet light absorber to compound and add to a liquid crystal polymer material, it can well cover the UV-A and UV-B bands of ultraviolet light and absorb a wide range of ultraviolet light, thereby improving the yellowing resistance of the liquid crystal polymer material.

[0015] However, if the composite ultraviolet light absorber is only directly added to the liquid crystal polymer material, the improvement of the yellowing resistance is not obvious. The inventors continued to study and found that further adding a certain amount of glycidyl methacrylate polymers not only has good thermal stability and is not easy to degrade at the high processing temperature of the liquid crystal polymer material, but also utilizes the high polarity of the epoxy group of the glycidyl methacrylate polymer to selectively distribute the composite ultraviolet light absorber in the glycidyl methacrylate polymer, and then utilizes the characteristics of the liquid crystal polymer's high crystallinity and the difference in compatibility with the glycidyl methacrylate polymer to induce the composite ultraviolet light absorber to migrate and approach the surface of the material, further improving the ultraviolet yellowing resistance of the liquid crystal polymer material.

[0016] In the present invention, liquid crystal polymer is used as the main resin; preferably, the liquid crystal polymer is 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 the art can be used in the present invention. For example, liquid crystal polymers polymerized from aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids with at least one compound of aromatic diols or aromatic hydroxylamines; or liquid crystal polymers polymerized from different aromatic hydroxycarboxylic acids; or liquid crystal polymers polymerized from aromatic dicarboxylic acids with aromatic diols, aromatic hydroxylamines 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 polymer can be measured by differential scanning calorimetry. The test process is: heating rate 20℃ / min, heating to 30℃ above the melting point and staying for 5 minutes to eliminate the thermal history, and taking the curve of the second heating to obtain the melting point Tm.

[0020] Optionally, the intrinsic viscosity of the liquid crystal polymer is 3.0 to 7.0 dL / g (eg, 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 an Usher viscometer at 80° C., and the solvent is pentafluorophenol.

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

[0022] Preferably, the triazine ultraviolet light absorber is at least one of 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol, 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 light 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, and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0024] Preferably, the benzophenone ultraviolet light 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 light absorber includes but is not limited to 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-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 1:0.2-0.4; the average particle size of the titanium dioxide is 100-400 nm; the average particle size of the silicon dioxide is 15-50 nm.

[0028] Titanium dioxide can usually only be achieved at the submicron level. By selecting this compound light-shielding agent, silicon dioxide with a smaller particle size can be filled in the gaps of titanium dioxide, thereby achieving a better light-shielding effect and making the liquid crystal polymer material more resistant to ultraviolet yellowing.

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

[0030] More preferably, the crystal form of the titanium dioxide is rutile.

[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 ethylene-butyl acrylate-glycidyl methacrylate copolymer.

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

[0034] More preferably, the ethylene unit content in the ethylene-glycidyl methacrylate copolymer is 85-95 wt%, and the glycidyl methacrylate unit content is 5-15 wt%.

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

[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 measured according to ASTM D-1238-2010 standard.

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

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

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

[0040] Preferably, the liquid crystal polymer material further comprises 0.2 to 1 part of other auxiliary agents.

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

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

[0043] The method for preparing the liquid crystal polymer material comprises 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 of the melt extruder is 300-500 rpm, and the screw aspect ratio is 35-50:1.

[0045] The application of the above liquid crystal polymer material in the preparation of components of electronic products is also within the protection scope of the present invention.

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

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The invention realizes a significant improvement in the resistance to ultraviolet yellowing of liquid crystal polymer materials by combining a light shielding agent, a composite light ultraviolet absorber and a glycidyl methacrylate polymer, so that the liquid crystal polymer materials can be used in the fields of servers, notebook computer fans, cooling fans of e-sports equipment or electronic connectors. DETAILED DESCRIPTION

[0049] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0050] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0051] Liquid crystal polymer 1#: homemade, the preparation process is as follows: p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA) are thrown into a reaction vessel containing an acetic anhydride acylation dose in a molar ratio of 73:27, and then the reactor is placed in a 240°C salt bath pot for reflux for 2 hours, and after the by-product acetic acid is no longer distilled out, the reactor is heated to 300°C at a heating rate of 5°C / min, and the acetic acid and unreacted raw material small molecules are discharged from the distillation column, and then the internal pressure of the reaction vessel is reduced to below 10 kPa, and this pressure is maintained until the power of the stirring paddle reaches 7 kW, and the material is discharged and pelletized to obtain liquid crystal polymer 1#.

[0052] Liquid crystal polymer 2#: homemade. The preparation process is different from that of liquid crystal polymer 1# in that p-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA) are added to a reaction vessel containing an acetic anhydride acylation agent at a molar ratio of 70:30.

[0053] Liquid crystal polymer 3#: purchased from Polyplastics Co., Ltd. of Japan, brand name Vectra A950, melting point is 280℃.

[0054] Liquid crystal polymer 4#: purchased from Polyplastics Co., Ltd. of Japan, brand name Vectra C950, melting point is 320℃.

[0055] The first ultraviolet light absorber: a triazine ultraviolet light absorber, 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxy-phenol, commercially available;

[0056] The second ultraviolet light absorber 1#: a benzotriazole ultraviolet light absorber, 2,2'-methylenebis(4-tert-octyl-6-benzotriazolephenol), commercially available;

[0057] The second ultraviolet light absorber 2#: a benzoxazine ultraviolet light absorber, 2,2'-(1,4-phenylene)bis-4H-3,1-benzoxazin-4-one, commercially available;

[0058] The second ultraviolet light absorber 3#: a benzophenone ultraviolet light absorber, 2-hydroxy-4-n-octyloxybenzophenone, commercially available;

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

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

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

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

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

[0064] Composite ultraviolet light absorber 5#: obtained by mixing the first ultraviolet light absorber and the other ultraviolet light absorber 1# in a mass ratio of 1:1.

[0065] Composite ultraviolet light absorber 6#: obtained by mixing other ultraviolet light absorber 1# and second ultraviolet light 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#: 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 Dekedaojin 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 bisstearamide: P-200, Guangzhou Xihuan Chemical Technology Co., Ltd.;

[0072] Glass fiber: ECS10-03-584A, China Jushi Co., Ltd.

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

[0074] Unless otherwise specified, the components (such as other auxiliary agent 1#, etc.) selected in each parallel example and comparative example are the same commercially available products.

[0075] The performance of the liquid crystal polymer materials provided in the embodiments and comparative examples of the present invention was measured according to the following test methods:

[0076] 1. UV yellowing resistance test: Each liquid crystal polymer material is injection molded into a standard test plate, and tested according to ISO48922cycle2 conditions. After 144 hours of irradiation, the color difference of the standard plate is tested. Each sample is tested three times, and the average of the three color differences is taken.

[0077] 2. Mechanical properties test: Tensile strength test: Tested under ISO527-1 / -2 conditions, 10mm / min tensile speed, and the average value of 5 test results. Flexural modulus test: Tested under ISO178 conditions, 2mm / min bending speed, and the average value of 5 test results.

[0078] The preparation process of the liquid crystal polymer material of each embodiment and comparative example of the present invention is as follows: weigh each component according to the formula, add the components except glass fiber (if any) and light shielding agent from the main feed port of the twin-screw extruder, add glass fiber (if any) and light shielding agent from the side feed port of the twin-screw extruder, melt extrude at a temperature 20°C higher than the melting point of the liquid crystal polymer, cool and granulate to obtain the liquid crystal polymer material. The screw speed of the twin-screw extruder is 400rpm, and the screw aspect ratio is 40:1.

[0079] Examples 1 to 14

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

[0081] Table 1 Formulas of Examples 1 to 7 (parts by weight)

[0082]

[0083] Table 2 Formulas of Examples 8 to 14 (parts by weight)

[0084]

[0085]

[0086] Comparative Examples 1 to 8

[0087] Comparative Examples 1 to 8 provide a series of liquid crystal polymer materials, and their formulations are shown in Table 3.

[0088] Table 3 Formulas of Comparative Examples 1 to 8 (parts by weight)

[0089]

[0090] The properties of the liquid crystal polymer materials of the embodiments and comparative examples were measured according to the above-mentioned test methods. The test results are shown in Table 4.

[0091] Table 4 Performance test results of liquid crystal polymer materials of various embodiments and comparative examples

[0092]

[0093] From Table 4, we can see that:

[0094] The ΔE of the UV yellowing resistance test of the liquid crystal polymer materials of Examples 1 to 14 is less than 8.8, indicating that the liquid crystal polymer materials of the present invention have good UV yellowing resistance. In addition, 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 ultraviolet light absorber selected in Comparative Examples 1-2 is not suitable. Comparative Examples 3-4 add a single ultraviolet light absorber, and the liquid crystal polymer material has poor resistance to ultraviolet yellowing. Comparative Example 5 does not add a light shielding agent, and the liquid crystal polymer material has poor resistance to ultraviolet yellowing. Comparative Example 6 does not add a glycidyl methacrylate polymer, and the liquid crystal polymer material has poor resistance to ultraviolet yellowing. In Comparative Example 7, too much glycidyl methacrylate polymer is added, resulting in excessive melt viscosity of the liquid crystal polymer material, and the composite ultraviolet light absorber cannot be well dispersed and close to the surface of the material, resulting in poor resistance to ultraviolet yellowing of the liquid crystal polymer material. Comparative Example 8 adds commonly used ethylene bisstearamide with dispersing effect, but the degree of improvement in the resistance to ultraviolet yellowing of the liquid crystal polymer material is not obvious.

[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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A liquid crystal polymer material, characterized in that: The composition comprises the following components in parts by weight: 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 a triazine ultraviolet light absorber, and the second ultraviolet light absorber is at least one of a benzotriazole ultraviolet light absorber, a benzophenone ultraviolet light absorber or a benzoxazine ultraviolet light absorber.

2. The liquid crystal polymer material according to claim 1, characterized in that: The melting point of the liquid crystal polymer is 270-330°C.

3. The liquid crystal polymer material according to claim 1, characterized in that: The light shielding agent is at least one of titanium dioxide, zinc oxide or silicon dioxide.

4. The liquid crystal polymer material according to claim 3, characterized in that: The light shielding agent is titanium dioxide and silicon dioxide compounded in a mass ratio of 1:0.2-0.4; the average particle size of the titanium dioxide is 100-400nm; the average particle size of the silicon dioxide is 15-50nm.

5. The liquid crystal polymer material according to claim 1, characterized in that: 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.

6. The liquid crystal polymer material according to claim 1, characterized in that: The mass ratio of the composite ultraviolet light absorber to the glycidyl methacrylate polymer is (8-11):(2-5).

7. The liquid crystal polymer material according to claim 1, characterized in that: The liquid crystal polymer material also includes 10 to 30 parts of glass fiber.

8. The liquid crystal polymer material according to claim 1, characterized in that: The liquid crystal polymer material also includes 0.2 to 1 part of other auxiliary agents.

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

10. Use of the liquid crystal polymer material according to any one of claims 1 to 8 in preparing components of electronic products.

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