Liquid crystal polymer composition, as well as its manufacturing method and use.

Abstract

The present invention discloses a liquid crystal polymer composition and its manufacturing method and use. The liquid crystal polymer composition of the present invention comprises 100 parts by weight of a liquid crystal polymer resin, 10 to 80 parts by weight of a fibrous filler, and 15 to 80 parts by weight of a flake filler, wherein the mass ratio of the fibrous filler to the flake filler is (0.2 to 2:1), the weight percentage of the fibrous filler having a retention length of 100 μm or less is 50% or more, and the weight percentage of the fibrous filler having a retention length of 250 μm or more is 1% to 5%, and the flake filler is composed of fine flake filler having a particle diameter D50 of 2.5 to 4.5 μm and coarse flake filler having a particle diameter D50 of 48 to 70 μm in a mass ratio of (0.5 to 2:1). In the present invention, fibrous fillers of different retention lengths are interwoven to form an entangled structure, and then combined with fine flake fillers, thereby uniformly dispersing the coarse flake fillers and effectively improving the shrinkage difference between the direction perpendicular to the flow direction of the liquid crystal polymer composition and the flow direction, thereby effectively resolving the problem of flake filler aggregation.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer compound compositions, and more specifically to a liquid crystal polymer composition, and a method for producing and use thereof.

Background Art

[0002] Liquid crystal polymers have excellent properties such as heat resistance, fluidity, dimensional stability, and self-extinguishing properties, and are widely applied to small precision electronic components such as electronic connectors, coil bobbins, and relays. Furthermore, with the development of electronic technology, electronic connectors on PCB substrates tend to be thinner, more highly integrated, and multifunctional.

[0003] Although LCP (liquid crystal polymer) materials have many performance advantages in precision electronic connectors, due to their rigid rod-like molecular chain structure, after injection molding, especially when producing elongated products (e.g., FPC / DDR / BtoB, etc.), the molecular chains become highly oriented, and the difference in shrinkage between the orientation direction (flow direction) and the direction perpendicular thereto becomes extremely large. As a result, problems occur such as large variations in the external dimensions of the product, oblique twisting, and deformation.

[0004] In order to obtain an LCP material composite material with better dimensional stability, conventional prior art mainly solves this problem by adding flake fillers. However, since LCP molecular chains have high rigidity, low polarity, and poor wettability with inorganic fillers, it is extremely difficult to uniformly disperse inorganic fillers in LCP, large aggregates are formed, which further causes problems such as gate clogging, insufficient adhesive in products, and white spots on product surfaces.

Summary of the Invention

Problem to be Solved by the Invention

[0005] The object of the present invention is to overcome the disadvantages and drawbacks of conventional methods of modifying liquid crystal polymers with flake-like fillers, such as the difficulty in uniformly dispersing the flake-like fillers, and to provide a liquid crystal polymer composition that improves the uniformity of dispersion of coarse flake-like fillers in liquid crystal polymer resins by combining specific fibrous fillers and fine flake-like fillers, thereby improving the difference in shrinkage between the direction perpendicular to the flow direction (Traverse Direction, TD) and the flow direction (machine direction, MD), while reducing molding problems such as gate clogging and insufficient adhesive due to aggregation of coarse flake-like fillers, as well as appearance problems such as white spots on the surface.

[0006] Another object of the present invention is to provide a method for producing a liquid crystal polymer composition.

[0007] A further object of the present invention is to provide the use of the above-mentioned liquid crystal polymer composition in the manufacture of thin-walled electronic connectors.

[0008] A further object of the present invention is to provide a thin-walled electronic connector manufactured using the above-mentioned liquid crystal polymer composition as a raw material. [Means for solving the problem]

[0009] The above-mentioned objectives of the present invention are achieved by the following technical solutions.

[0010] A liquid crystal polymer composition, comprising: 100 parts by weight of liquid crystal polymer resin, 10 to 80 parts by weight of fibrous filler, It contains 15 to 80 parts by weight of flake-like filler, The mass ratio of the fibrous filler to the flake filler is (0.2~2):1. In the fibrous filler, the weight percentage of fibrous filler with a retention length of 100 μm or less is 50% or more, and the weight percentage of fibrous filler with a retention length of 250 μm or more is 1% to 5%. The aforementioned flake-shaped filler consists of fine flake-shaped fillers with a particle size D50 of 2.5 to 4.5 μm and coarse flake-shaped fillers with a particle size D50 of 48 to 70 μm, in a mass ratio of (0.5 to 2):1.

[0011] In this invention, inorganic fillers are formed by blending specific fibrous fillers, fine flake fillers, and coarse flake fillers in specific proportions. Furthermore, by adjusting the content of fibrous fillers with a retention length of 100 μm or less and fibrous fillers with a retention length of 250 μm or more in the liquid crystal polymer composition, the dispersibility of coarse flake fillers in the liquid crystal polymer composition is improved by utilizing fibrous fillers and fine flake fillers with different retention lengths. Here, fibrous fillers with different retention lengths are interwoven to form an entangled structure, which contributes to reducing the tendency of coarse flake fillers to aggregate. In addition, fine flake fillers can fill the spaces between the layers of coarse flake fillers, thereby breaking up existing aggregates and allowing the liquid crystal polymer resin to permeate between the layers of coarse flake fillers, achieving uniform dispersion of coarse flake fillers. Furthermore, the fibrous fillers, distributed as an entangled structure, can effectively suppress the orientation of uniform liquid crystal polymer resin molecular chains. Combined with uniformly dispersed flake-like fillers, this effectively improves the shrinkage difference between the direction perpendicular to the flow direction (TD) and the direction of flow (MD) of the liquid crystal polymer composition, effectively solving problems caused by the aggregation of flake-like fillers.

[0012] Preferably, the mass ratio of the fibrous filler to the flake filler is 0.3 to 1.7.

[0013] In specific embodiments, the flake-like filler described in the present invention may be mica powder and / or talc.

[0014] In a specific embodiment, the coarse flake-like filler described in the present invention is mica powder, and the fine flake-like filler is talc.

[0015] In a specific embodiment, the melting point Tm of the liquid crystal polymer resin described in the present invention is 350±10℃.

[0016] In specific embodiments, the average diameter of the fibrous filler described in the present invention is 5 to 20 μm.

[0017] Specifically, the weight percentage of fibrous fillers with a retained length of 100 μm or less in the fibrous filler is 51% to 91%.

[0018] The present invention also, The method for producing a liquid crystal polymer composition includes the steps of feeding liquid crystal polymer through the main feed port of a twin-screw extruder, feeding fibrous filler and flake filler through the side feed port of the twin-screw extruder, then melting and extruding at a temperature of Tm ± 30°C to perform granulation, where Tm is the melting point of the liquid crystal polymer.

[0019] In the method for producing the liquid crystal polymer composition of the present invention, the fiber retention length and content distribution in the final liquid crystal polymer composition are controlled mainly by changing the position where the fibrous filler is added. Furthermore, the particle size of the flake-like filler and the amount added also have some influence on the fiber retention length and content distribution in the liquid crystal polymer composition.

[0020] The use of liquid crystal polymer compositions in the manufacture of thin-walled electronic components is also within the scope of protection of this invention.

[0021] The present invention also protects thin-walled electronic connectors manufactured using the above-mentioned liquid crystal polymer composition as a raw material. [Effects of the Invention]

[0022] Compared to the prior art, the present invention has the following beneficial effects.

[0023] The liquid crystal polymer composition of the present invention is formed by blending specific fibrous filler, fine flake filler and coarse flake filler in specific proportions to form an inorganic filler, and further adjusting the content of fibrous fillers with different retention lengths in the liquid crystal polymer composition, whereby the dispersibility of the coarse flake filler in the liquid crystal polymer composition is improved by using the fibrous fillers with different retention lengths and the fine flake filler, and the difference in shrinkage between the direction perpendicular to the flow direction and the flow direction of the liquid crystal polymer composition can be effectively improved. Here, the ratio α of the shrinkage rate in the direction perpendicular to the flow direction (TD) to the shrinkage rate in the flow direction (MD) is 4.1 to 9.7, and the dispersion uniformity of the filler reaches grade B or above. MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, the present invention will be further described with reference to modes for carrying out the invention, but these examples do not limit the present invention in any way. The raw materials and reagents used in the examples of the present invention are commercially available unless otherwise specified.

[0025] 1. Raw materials and reagents Liquid crystal polymer resin: the melting point Tm of the liquid crystal polymer resin is 350±10°C, manufactured by Zhuhai Wantong Special Engineering Plastics Co., Ltd., product number Vicryst R800 Glass fiber A: average diameter 10 μm, initial average length 3 mm, manufactured by Owens Corning, product number 923 Glass fiber B: average diameter 6 μm, initial average length 3 mm, manufactured by Owens Corning, product number FT771 Flake filler A: mica powder, particle diameter D50 48 μm, manufactured by Guirui Mining Co., Ltd., product number GM-5 Flake filler B: mica powder, particle diameter D50 70 μm, manufactured by Guirui Mining Co., Ltd., product number GP-100 Flake filler C: mica powder, particle diameter D50 24 μm, manufactured by Yamaguchi Mica Co., Ltd., product number AB-25S Flake filler D: talc, particle diameter D50 2.5 μm, manufactured by Longsheng Huamei Co., Ltd., product number AH-3000 Flake-type filler E: Talc, particle size D50 4.5 μm, manufactured by Liaoning Aihai Talc Co., Ltd., product code AH 51215 Flake-shaped filler F: Talc, particle size D50 6μm, manufactured by Liaoning Aihai Talc Co., Ltd., product number AH 51220.

[0026] 2. The liquid crystal polymer compositions in the examples and comparative examples of the present invention are manufactured by the following manufacturing method. S1. Weigh each component according to its mixing ratio. S2. Set the processing temperature of the twin-screw extruder to 320°C to 380°C. S3. Liquid crystal polymer resin is fed into the main feed port of the twin-screw extruder. S4. Fibrous fillers and flake fillers are introduced through the side feed port of a twin-screw extruder, and fibrous fillers with different lengths and content distributions are obtained mainly by adjusting the position of the screw of the twin-screw extruder into which the fibrous filler is introduced. The particle size of the flake filler and the amount added also affect to some extent the retained length and content distribution of fibers in the liquid crystal polymer composition. S5. The molten material, which has been blended and modified using a twin-screw extruder with a specific screw combination, is extruded in strand form from the die head, cooled in a water bath, pulled to a pelletizer, shredded and pelletized, and finally, a uniform liquid crystal polymer composite material is obtained.

[0027] 3. Performance testing

[0028] (1) Glass fiber retention length and weight ratio The specific test method is as follows: A liquid crystal polymer composite material obtained from a twin-screw extruder was prepared, and the ash content of the composite material was obtained by referring to ISO 3451-1. The ash content was placed in 100 mL of 95% industrial alcohol, dispersed using an ultrasonic device for 2 minutes, then 2 mL was taken from the bottom with a pipette, placed on a clean glass slide, and photographed under an optical microscope at 500x magnification. The retained length of the glass fibers was calculated using statistical methods. 1,000 glass fibers were randomly selected and measured, and the total length of glass fibers below or above a specific length (L1) and the total length of all glass fibers (L0) were calculated. Since the diameter and density of the glass fibers are constant, the weight percentage of glass fibers below or above a specific length = L1 / L0 × 100%.

[0029] (2) The ratio α of the contraction rate in the direction perpendicular to the flow direction (TD) to the contraction rate in the flow direction (MD). The specific test method is as follows: First, a liquid crystal polymer composite material obtained from a twin-screw extruder was prepared, and 20 sample plates (sample plate size: length in the flow direction 70 mm, width perpendicular to the flow direction 30 mm, thickness 1.5 mm) were formed by injection molding in a single-screw injection molding machine using a single-gate mold. Next, the actual length of the sample plate perpendicular to the flow direction was measured in two dimensions. The ratio of this actual length to the theoretical length of the mold used is the shrinkage rate perpendicular to the flow direction. The average value of the shrinkage rates perpendicular to the flow direction of 20 sample plates was defined as Y. Furthermore, the actual length of the sample plate in the flow direction was measured in two dimensions. The ratio of this actual length to the theoretical length of the mold used is the shrinkage rate in the flow direction. The average value of the shrinkage rates in the flow direction of 20 sample plates was defined as X. Finally, the ratio of the contraction rate perpendicular to the flow direction (TD) to the contraction rate in the flow direction (MD) was determined using the equation α = Y / X.

[0030] (3) Dispersion uniformity of the filler The specific test method was as follows: First, a liquid crystal polymer composite material obtained from a twin-screw extruder was prepared, and 20 square sample plates measuring 64 mm × 64 mm × 0.8 mm were molded using a single-screw injection molding machine. Next, using an optical microscope, the sample plates were magnified 200 times, and the size and number of white dots on the front and back surfaces were statistically measured. Finally, the uniformity of the filler dispersion was evaluated according to the following criteria. Grade A: Number of white spots larger than 0.2mm ≤ 1 Grade B: 1 < Number of white spots larger than 0.2 mm ≤ 10 Grade C: 10 < Number of white spots larger than 0.2mm ≤ 30 Grade D: 30 < Number of white spots larger than 0.2 mm in size Examples 1-14

[0031] Table 1 shows the parts by weight of each component of the liquid crystal polymer compositions of Examples 1 to 14. Here, M1 is the mass ratio of fibrous filler to flake filler, M2 is the mass ratio of fine flake filler to coarse flake filler, N is the weight percentage of fibrous filler with a retaining length of 100 μm or less in the fibrous filler, and Z is the weight percentage of fibrous filler with a retaining length of 250 μm or more in the fibrous filler.

[0032] JPEG0007912677000001.jpg165122 Comparative Examples 1~9

[0033] Table 2 shows the parts by weight of each component of the liquid crystal polymer compositions of Comparative Examples 1 to 9. Here, M1 is the mass ratio of fibrous filler to flake filler, M2 is the mass ratio of fine flake filler to coarse flake filler, N is the weight percentage of fibrous filler with a retaining length of 100 μm or less, and Z is the weight percentage of fibrous filler with a retaining length of 250 μm or more.

[0034] JPEG0007912677000002.jpg89124

[0035] Table 3 shows the results of evaluating the performance of the liquid crystal polymer compositions of each example and comparative example according to the method described above.

[0036] JPEG0007912677000003.jpg225116

[0037] In the liquid crystal polymer composition of the present invention, the ratio α of the shrinkage rate in the direction perpendicular to the flow direction (TD) to the shrinkage rate in the flow direction (MD) is 4.1 to 9.7, and the uniformity of the filler dispersion is of grade B or higher. Furthermore, from Example 1, Comparative Example 1, and Comparative Example 2, it was found that when flake-shaped filler is added in excess, the uniformity of the filler dispersion decreases due to aggregation of the flake-shaped filler, while when fibrous filler is added in excess, it becomes difficult to effectively improve the ratio α of the shrinkage rate in the direction perpendicular to the flow direction (TD) to the shrinkage rate in the flow direction (MD) of the liquid crystal polymer.

[0038] As is clear from Example 1, Comparative Example 3, and Comparative Example 4, if the amount of fine flake filler added is too small, it becomes difficult to improve the uniformity of the dispersion of coarse flake filler by combining it with fibrous fillers of different retention lengths. On the other hand, if an excessive amount of fine flake filler is added, the excess fine flake filler tends to aggregate, similarly inhibiting the dispersion of coarse flake filler.

[0039] From Example 1 and Comparative Examples 5-7, it was found that if both the particle size D50 of the fine flake-like filler being 2.5-4.5 μm and the particle size D50 of the coarse flake-like filler being 48-70 μm cannot be simultaneously satisfied, the effect of fibrous fillers and fine flake-like fillers on improving the dispersion uniformity of the coarse flake-like filler is limited. Furthermore, from Example 1 and Comparative Example 8, it was found that in the fibrous filler, if the content of fibrous fillers with a retention length of 100 μm or less is too low and the content of fibrous fillers with a retention length of 250 μm or more is too high, the reduction of the ratio α of the shrinkage rate in the direction perpendicular to the flow direction (TD) to the shrinkage rate in the flow direction (MD) of the liquid crystal polymer composition is inhibited, leading to increased variation in the external dimensions of the product and exacerbating problems such as diagonal twisting and deformation.

[0040] The above embodiments of the present invention are merely illustrative examples for the purpose of clearly illustrating the present invention and do not limit the embodiments of the present invention. Those skilled in the art can make various other modifications and variations based on the above description. It is not necessary, nor is it possible, to comprehensively enumerate all embodiments. Any modifications, equivalent substitutions, and improvements made within the scope of 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 crystal polymer composition, comprising: 100 parts by weight of liquid crystal polymer resin, 10 to 80 parts by weight of fibrous filler, It comprises 15 to 80 parts by weight of flake-like filler, The mass ratio of the fibrous filler to the flake filler is (0.2 to 2):

1. In the fibrous filler described above, the weight percentage of fibrous filler with a retaining length of 100 μm or less is 51.2% or more, and the weight percentage of fibrous filler with a retaining length of 250 μm or more is 1.3% to 4.8%. The liquid crystal polymer composition is characterized in that the flake-like filler is composed of fine flake-like fillers with a particle size D50 of 2.5 to 4.5 μm and coarse flake-like fillers with a particle size D50 of 48 to 70 μm in a mass ratio of (0.5 to 2):

1.

2. The liquid crystal polymer composition according to claim 1, characterized in that the mass ratio of the fibrous filler to the flake-like filler is 0.3 to 1.

7.

3. The liquid crystal polymer composition according to claim 1, characterized in that the flake-like filler is mica powder and / or talc.

4. The liquid crystal polymer composition according to claim 3, characterized in that the coarse flake-like filler is mica powder and the fine flake-like filler is talc.

5. The liquid crystal polymer composition according to claim 1, characterized in that the melting point Tm of the liquid crystal polymer resin is 350 ± 10°C.

6. The liquid crystal polymer composition according to claim 1, characterized in that the average diameter of the fibrous filler is 5 to 20 μm.

7. The liquid crystal polymer composition according to claim 1, characterized in that the weight percentage of fibrous fillers with a retained length of 100 μm or less in the fibrous filler is 51.2% to 91%.

8. A method for producing a liquid crystal polymer composition according to any one of claims 1 to 7, A manufacturing method characterized by comprising the steps of feeding a liquid crystal polymer from the main feed port of a twin-screw extruder, feeding fibrous filler and flake-like filler from the side feed port of the twin-screw extruder, then melting and extruding at a temperature of Tm ± 30°C to perform granulation and obtain a liquid crystal polymer composition, wherein Tm is the melting point of the liquid crystal polymer.

9. Use of the liquid crystal polymer composition according to any one of claims 1 to 7 in the manufacture of a thin-walled electronic connector.

10. A thin-walled electronic connector characterized by being manufactured using a liquid crystal polymer composition according to any one of claims 1 to 7 as a raw material.

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