Liquid crystal polymer composition, and method of making and use thereof

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 polymeric compositions, and more particularly to liquid crystalline polymer compositions, as well as methods for their preparation and use. [Background technology]

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

[0003] Although LCP (liquid crystal polymer) materials have many performance advantages when used in precision electronic connectors, their rigid, rod-like molecular chain structure causes the molecular chains to become highly oriented after injection molding, especially when manufacturing long products (such as FPC / DDR / BtoB), resulting in a very large difference in shrinkage rate between the orientation direction (flow direction) and the direction perpendicular to it.As a result, problems such as large variations in the product's external dimensions and diagonal twisting and deformation occur.

[0004] Previously disclosed technologies have mainly solved this problem by adding flake fillers to obtain LCP composites with better dimensional stability. However, due to the high rigidity and low polarity of LCP molecular chains and poor wettability with inorganic fillers, it is extremely difficult to uniformly disperse the inorganic fillers in the LCP, resulting in the formation of large aggregates, which can lead to problems such as gate clogging, insufficient adhesiveness in the product, and white spots on the product surface. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to overcome the drawbacks and shortcomings of the conventional flake filler, which is that it is difficult to uniformly disperse the flake filler when modifying a liquid crystal polymer, and to provide a liquid crystal polymer composition which improves the uniformity of dispersion of the coarse flake filler in the liquid crystal polymer resin by combining a specific fibrous filler with a fine flake filler, thereby improving the shrinkage difference between the transverse direction (TD) and the machine direction (MD), while reducing molding problems such as gate clogging and insufficient adhesive due to aggregation of the coarse flake filler, and appearance problems such as white spots on the surface.

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

[0007] A further object of the present invention provides the use of the above liquid crystalline 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 from the above liquid crystal polymer composition. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following technical solutions.

[0010] A liquid crystal polymer composition comprising: 100 parts by weight of a liquid crystal polymer resin; 10 to 80 parts by weight of a fibrous filler; 15 to 80 parts by weight of a flake filler, The mass ratio of the fibrous filler to the flake filler is (0.2 to 2):1, In the fibrous filler, 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%; 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).

[0011] In the present invention, a specific fibrous filler, a microflake filler, and a coarse flake filler are blended in a specific ratio to form an inorganic filler, and the content of the fibrous filler with a retention length of 100 μm or less and the content of the fibrous filler with a retention length of 250 μm or more in the liquid crystal polymer composition are adjusted to use the fibrous fillers and microflake fillers with different retention lengths to improve the dispersibility of the coarse flake filler in the liquid crystal polymer composition. Here, the fibrous fillers with different retention lengths are interwoven to form an entangled structure, which contributes to reducing the tendency of the coarse flake filler to aggregate, and the microflake filler can be filled between the layers of the coarse flake filler, thereby breaking up the existing aggregates and allowing the liquid crystal polymer resin to penetrate between the layers of the coarse flake filler, thereby achieving uniform dispersion of the coarse flake filler. Furthermore, the fibrous filler distributed in an entangled structure can effectively suppress the uniform orientation of the liquid crystal polymer resin molecular chains, and combined with the uniformly dispersed flake filler, can effectively improve the shrinkage difference between the transverse direction (TD) and the flow direction (MD) of the liquid crystal polymer composition, and effectively solve problems caused by the aggregation of the flake filler.

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

[0013] In a specific embodiment, the flaky filler according to the present invention may be mica powder and / or talc.

[0014] In a specific embodiment, the coarse flake filler according to the present invention is mica powder and the fine flake filler is talc.

[0015] In a specific embodiment, the melting point Tm of the liquid crystal polymer resin according to the present invention is 350±10°C.

[0016] In a specific embodiment, the average diameter of the fibrous filler according to the present invention is between 5 and 20 μm.

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

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

[0019] In the method for producing a liquid-crystalline polymer composition of the present invention, the fiber retention length and content distribution in the final liquid-crystalline polymer composition are controlled mainly by changing the position of the fibrous filler. In addition, the particle size and amount of the flake filler also have some effect on the fiber retention length and content distribution in the liquid-crystalline polymer composition.

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

[0021] The present invention also provides protection for thin-walled electronic connectors made from the liquid crystal polymer compositions described above. [Effects of the Invention]

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

[0023] The liquid crystal polymer composition of the present invention is an inorganic filler formed by blending a specific fibrous filler, a microflake filler, and a coarse flake filler in a specific ratio, and further adjusting the content of the fibrous filler with different retention lengths in the liquid crystal polymer composition, thereby improving the dispersibility of the coarse flake filler in the liquid crystal polymer composition by utilizing the fibrous filler and the microflake filler with different retention lengths, and effectively improving the shrinkage difference between the direction perpendicular to the flow direction and the flow direction of the liquid crystal polymer composition. 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 filler dispersion uniformity reaches Class B or higher. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be further described below with reference to the following examples, which are not intended to limit the present invention in any way. Raw materials and reagents used in the examples of the present invention are commercially available unless otherwise specified.

[0025] 1. Raw material reagents Liquid crystal polymer resin: Melting point Tm of liquid crystal polymer resin 350±10℃, 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 size D50 48 μm, manufactured by Gerui Mining Co., Ltd., product number GM-5 Flake filler B: Mica powder, particle size D50 70 μm, manufactured by Gerui Mining Co., Ltd., product number GP-100 Flake filler C: Mica powder, particle size D50 24 μm, manufactured by Yamaguchi Mica Co., Ltd., product number AB-25S Flake filler D: Talc, particle size D50 2.5 μm, manufactured by Longsheng Huamei Co., Ltd., product number AH-3000 Flake filler E: Talc, particle size D50 4.5μm, manufactured by Liaoning Aihai Talc Co., Ltd., product number AH 51215 Flake filler F: talc, particle size D50 6 μm, 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 produced by the following production method. S1. Weigh out each component according to the mixing ratio. S2. Set the processing temperature of the twin-screw extruder to 320℃~380℃. S3. Liquid crystal polymer resin is fed into the main feed port of the twin-screw extruder. S4. The fibrous filler and flake filler are added through the side feed port of the twin-screw extruder, and the position of the screw of the twin-screw extruder into which the fibrous filler is added is mainly adjusted to obtain fibrous fillers with different lengths and content distributions. The particle size and amount of the flake filler also affect the fiber retention length and content distribution in the liquid crystalline polymer composition to some extent. S5. The modified melt is blended in a twin-screw extruder with a specific screw combination, extruded in the form of a strand from the die head, cooled in a water bath, drawn to a pelletizer, chopped and pelletized, and finally a uniform liquid crystal polymer composite is obtained.

[0027] 3. Performance testing

[0028] (1) Retention length and weight ratio of glass fibers The specific test method is as follows: Liquid crystal polymer composites obtained using a twin-screw extruder were prepared, and the ash content of the composites was determined according to ISO 3451-1. The ash was added to 100 mL of 95% industrial alcohol and dispersed for 2 minutes using an ultrasonic device. 2 mL was then pipetted from the bottom and placed on a clean glass slide. Photographs were taken at 500x magnification using an optical microscope. Statistical methods were used to calculate the retention length of the glass fibers. 1,000 glass fibers were randomly selected and measured, and the total length (L1) of glass fibers below or above a certain length and the total length (L0) of all glass fibers were calculated. Since the diameter and density of the glass fibers are constant, the weight percentage of glass fibers below or above a certain length = L1 / L0 × 100%.

[0029] (2) The ratio of the shrinkage rate in the direction perpendicular to the flow direction (TD) to the shrinkage rate in the flow direction (MD) α The specific test method was as follows: First, a liquid crystal polymer composite material obtained using 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 into a single-gate mold using a single-screw injection molding machine. Next, the actual length of the sample plates in the direction perpendicular to the machine direction was measured in two dimensions. The ratio of this actual length to the theoretical length of the mold used was the shrinkage rate in the direction perpendicular to the machine direction. The average shrinkage rate in the direction perpendicular to the machine direction for 20 sample plates was taken as Y. Furthermore, the actual length of the sample plates in the machine direction was measured in two dimensions. The ratio of this actual length to the theoretical length of the mold used was the shrinkage rate in the machine direction. The average shrinkage rate in the machine direction for 20 sample plates was taken as X. Finally, the ratio of the shrinkage rate in the transverse direction (TD) to the shrinkage rate in the machine direction (MD) was calculated using the formula α=Y / X.

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

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

[0032] JPEG2025532318000001.jpg165122 Comparative Examples 1~9

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

[0034] JPEG2025532318000002.jpg89124

[0035] The performance of the liquid crystal polymer compositions of each Example and Comparative Example was evaluated according to the above method, and the results are shown in Table 3.

[0036] JPEG2025532318000003.jpg225116

[0037] In the liquid crystal polymer composition of the present invention, the ratio α of the shrinkage rate in the transverse direction (TD) to the shrinkage rate in the machine direction (MD) is 4.1 to 9.7, and the filler dispersion uniformity is at least Class B. Furthermore, it was found from Example 1, Comparative Example 1, and Comparative Example 2 that if an excessive amount of flake filler is added, the dispersion uniformity of the filler decreases due to aggregation of the flake filler, while if an excessive amount of fibrous filler is added, it becomes difficult to effectively improve the ratio α of the shrinkage rate in the transverse direction (TD) to the machine 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 dispersion uniformity of the coarse flake filler by combining it with a fibrous filler having a different retention length; on the other hand, if too much fine flake filler is added, the excess fine flake filler tends to aggregate, which also hinders the dispersion of the coarse flake filler.

[0039] From Example 1 and Comparative Examples 5 to 7, it was found that if the particle diameter D50 of the fine flake filler is 2.5 to 4.5 μm and the particle diameter D50 of the coarse flake filler is 48 to 70 μm simultaneously, the effect of improving the dispersion uniformity of the coarse flake filler by the fibrous filler and the fine flake filler is limited. Furthermore, from Example 1 and Comparative Example 8, it was found that if the content of fibrous filler with a retention length of 100 μm or less is too low and the content of fibrous filler with a retention length of 250 μm or more is too high, the reduction of the ratio α of the shrinkage rate in the transverse direction (TD) to the shrinkage rate in the machine direction (MD) of the liquid crystal polymer composition is hindered, the variation in the external dimensions of the product increases, and the problems of diagonal twisting and deformation become more serious.

[0040] The above examples of the present invention are merely examples for the purpose of clearly explaining the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art may make various other modifications and variations based on the above description. It is not necessary or possible to comprehensively list all embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A liquid crystal polymer composition comprising: 100 parts by weight of a liquid crystal polymer resin; 10 to 80 parts by weight of a fibrous filler; 15 to 80 parts by weight of a flake filler; the mass ratio of the fibrous filler to the flake filler is (0.2 to 2):1; In the fibrous filler, 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%; The flake filler is composed of a fine flake filler having a particle diameter D50 of 2.5 to 4.5 μm and a coarse flake filler having a particle diameter D50 of 48 to 70 μm in a mass ratio of (0.5 to 2):

1.

2. 2. The liquid crystal polymer composition according to claim 1, wherein the mass ratio of the fibrous filler to the flake filler is 0.3 to 1.

7.

3. 2. The liquid crystal polymer composition according to claim 1, wherein the flake filler is mica powder and / or talc.

4. 4. The liquid crystalline polymer composition according to claim 3, wherein the coarse flake filler is mica powder and the fine flake filler is talc.

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

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

7. 2. The liquid crystal polymer composition according to claim 1, wherein the weight percentage of the fibrous filler having a retention length of 100 μm or less in the fibrous filler is 51% to 91%.

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

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

10. A thin-walled electronic connector, characterized in that it is produced using the liquid crystal polymer composition according to any one of claims 1 to 7 as a raw material.

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