Liquid crystal fiber reinforced polyester resin composition, preparation method therefor and use thereof

Abstract

Disclosed are a liquid crystal fiber reinforced polyester resin composition, a preparation method therefor and a use thereof. The liquid crystal fiber reinforced polyester resin composition comprises the following components in parts by weight: 100 parts of PCT resin; 5-50 parts of white pigment; 5-30 parts of liquid crystal fiber; and 0.5-5 parts of an auxiliary agent. The fineness of the liquid crystal fiber is 900-3200 D. In the present invention, liquid crystal fibers having a specific fineness are added to a PCT resin matrix material, so that a prepared composition has relatively good strength and reflectivity, and the strength and the reflectivity remain high after SMT processing.

Description

Liquid crystal fiber reinforced polyester resin composition and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and more specifically, to a liquid crystal fiber reinforced polyester resin composition, a preparation method and an application thereof. Background Art

[0002] Poly(1,4-cyclohexanedimethanol terephthalate) (PCT resin) is a high-temperature resistant, semi-crystalline thermoplastic. Due to its high heat resistance, excellent reflective efficiency, and good yellowing resistance, it is widely used in LED reflectors, reflector cups, scramblers, and LED housings.

[0003] However, after long-term use, it has been found that the strength and reflectivity of materials using PCT resin as the base resin cannot be simultaneously improved, which greatly restricts the application of such materials in LED materials. In particular, the strength of existing PCT resin-based materials is poor after surface mount technology (SMT), which limits their application, especially in LED reflector brackets. Therefore, there is a need in the art to develop a reinforced polyester resin composition that can achieve both good reflectivity and strength, without a significant decrease after SMT. Summary of the Invention

[0004] The purpose of the present invention is to provide a liquid crystal fiber reinforced polyester resin composition in order to overcome the defects or shortcomings of the polyester resin composition in the prior art, such as the inability to have both better strength and reflectivity and the obvious decrease in strength after SMT treatment.

[0005] Another object of the present invention is to provide a method for preparing the liquid crystal fiber reinforced polyester resin composition.

[0006] Another object of the present invention is to provide an application of the liquid crystal fiber reinforced polyester resin composition.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A liquid crystal fiber reinforced polyester resin composition, comprising the following components calculated in parts by weight:

[0009] Wherein, the fineness of the liquid crystal fiber is 900-3200D; the melting point of the liquid crystal fiber is ≥320°C.

[0010] The present invention provides a liquid crystal fiber-reinforced polyester resin composition. By using PCT resin as the base resin and adding liquid crystal fibers of a specific fineness combined with white pigment, the material exhibits excellent strength and high reflectivity. The inventors speculate that this may be because the liquid crystal fibers both provide reinforcement and have a similar structure to the PCT resin matrix, allowing for good bonding. However, excessively fine liquid crystal fibers can lead to difficulty in dispersion, resulting in significant shear heat generation during processing and poor reinforcement. Excessively fine liquid crystal fibers also have no effective reinforcement. Furthermore, the melting point of the liquid crystal fibers must be controlled to be ≥320°C. Lower melting points can lead to degradation during processing, making them difficult to disperse in the composition and preventing them from providing adequate reinforcement.

[0011] It should be noted that, in the liquid crystal fiber reinforced polyester resin composition of the present invention, the content of PCT resin is not less than 50 wt.%.

[0012] In the present invention, the fineness of the liquid crystal fiber is 900-3200D, for example, but not limited to, 900D, 1000D, 1100D, 1200D, 1300D, 1400D, 1500D, 1600D, 1700D, 1800D, 1900D, 2000D, 2100D, 2200D, 2300D, 2400D, 2500D, 2600D, 2700D, 2800D, 2900D, 3000D, 3100D, and 3200D, all of which can achieve the present invention. Furthermore, the fineness of the liquid crystal fiber is 1000-3000D. Furthermore, the fineness of the liquid crystal fiber is 1200-2000D.

[0013] It should be noted that the fineness described in the present invention refers to the diameter of the liquid crystal fiber, specifically the weight in grams of a 9,000-meter-long fiber at the specified moisture regain. For example, 1000D represents 1000 grams of the weight of a 9,000-meter-long fiber bundle.

[0014] Specifically, the fineness is calculated by measuring the mass of the liquid crystal fiber.

[0015] In the present invention, the melting point of the liquid crystal fiber is ≥320°C, for example but not limited to ≥325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C or 370°C, etc., which can realize the present invention.

[0016] Furthermore, the melting point of the liquid crystal fiber is 340-360°C.

[0017] Specifically, the melting point of the liquid crystal fiber is tested by DSC method, and the testing standard is ASTM D3418-2003.

[0018] Furthermore, the liquid crystal fiber can be commercially available or homemade.

[0019] Specifically, the method for preparing the liquid crystal fiber comprises the following steps:

[0020] Liquid crystal fibers of different fineness are prepared using liquid crystal resin through a melt spinning method.

[0021] In a specific embodiment, liquid crystal resin is used and then melt spinning is used to prepare liquid crystal fibers with finenesses of 200D, 1000D, 1200D, 1500D, 2000D, 3000D, and 5000D.

[0022] It should be noted that those skilled in the art should understand that the liquid crystal resin in the present invention is a polymer that exhibits melt anisotropy in a molten state.

[0023] In a specific embodiment, the liquid crystal resin is a type I resin, such as but not limited to Vicryst R8400 NC001 and / or Vicryst R8200 NC005.

[0024] Furthermore, the liquid crystal fiber reinforced polyester resin composition comprises the following components calculated in parts by weight:

[0025] In the present invention, there is no special requirement for the intrinsic viscosity of the PCT resin. In a specific embodiment, the intrinsic viscosity of the PCT resin is 0.6 to 0.8.

[0026] Furthermore, the intrinsic viscosity of the PCT resin is determined according to GB / T 10247-2008.

[0027] Furthermore, the average particle size of the white pigment is 0.1 to 0.5 μm.

[0028] Specifically, the average particle size of the white pigment is determined by measuring the particle size D50 value using a laser particle size analyzer.

[0029] In a specific embodiment, the white pigment is one or more of titanium oxide, zinc oxide, zinc sulfide, white lead, zinc sulfate, barium sulfate, barium carbonate or aluminum oxide.

[0030] The auxiliary agent includes one or more of an antioxidant, a lubricant or a weathering agent.

[0031] In the present invention, commonly used antioxidants can be selected according to existing technologies, such as but not limited to one or more of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants.

[0032] The hindered phenol antioxidant is one or more of N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide (Irganox 1098), pentaerythritol tetrakis[β-3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox 1010), triethylene glycol bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (Iragnox 259), β-(4-hydroxy-3,5-di-tert-butylphenyl) propionate n-octadecyl (Iragno 1076) or spiroethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (ADK AO-80).

[0033] The phosphite antioxidant is one or more of 2,4-di-tert-butylphenol (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol phosphite (PEP-36) or 627A.

[0034] The thioester antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol dodecylthiopropionate.

[0035] In the present invention, commonly used lubricants can be selected according to existing technologies, such as but not limited to at least one of amide lubricants, stearate lubricants, ester lubricants or silicone lubricants.

[0036] In the present invention, commonly used weathering agents can be selected according to existing technologies, such as but not limited to one or more of hindered amines, benzotriazoles, benzophenones or triazine benzylmalonates.

[0037] The present invention also protects a method for preparing the above-mentioned liquid crystal fiber reinforced polyester resin composition, comprising the following steps:

[0038] The PCT resin, white pigment, auxiliary agent and liquid crystal fiber are mixed evenly, melt-blended and extruded into granules in an extruder to obtain a liquid crystal fiber reinforced polyester resin composition.

[0039] Furthermore, the extruder is a twin-screw extruder.

[0040] Furthermore, the temperature of the extrusion granulation is 270-340°C.

[0041] Specifically, the temperature of zone one is 290-310°C; the temperature of zone two is 300-320°C; the temperature of zones three and four is 310-330°C; the temperature of zone five is 320-340°C; the temperature of zones six and seven is 300-320°C; the temperature of zone eight is 290-310°C; the temperature of zone nine is 270-290°C; and the temperature of zone ten is 280-300°C.

[0042] The present invention also protects the use of the liquid crystal fiber reinforced polyester resin composition in preparing LED bracket materials.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a liquid crystal fiber reinforced polyester resin composition. The composition is prepared by adding liquid crystal fibers of a specific fineness and combining with white pigment to PCT resin. The composition has high strength and reflectivity, and the strength and reflectivity remain high after multiple SMT packaging. The initial bending strength is not less than 85 MPa, the bending strength after SMT is not less than 75 MPa, and the bending strength retention rate is not less than 85%. The initial reflectivity is not less than 92%, the reflectivity after SMT is not less than 88%, and the reflectivity retention rate is not less than 94%. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0046] The raw materials used in the embodiments and comparative examples are:

[0047] PCT resin:

[0048] PCT resin 1: 0302, intrinsic viscosity 0.65, purchased from SK Chemicals;

[0049] PCT resin 2: 050, intrinsic viscosity 0.74, purchased from SK Chemicals;

[0050] Liquid crystal fiber:

[0051] Liquid crystal fiber 1: fineness 1000D, melting point 350℃, homemade;

[0052] Liquid crystal fiber 2: fineness 1200D, melting point 350℃, homemade;

[0053] Liquid crystal fiber 3: fineness 1500D, melting point 350℃, homemade;

[0054] Liquid crystal fiber 4: fineness 2000D, melting point 350℃, homemade;

[0055] Liquid crystal fiber 5: fineness 3000D, melting point 350℃, homemade;

[0056] Liquid crystal fiber 6: fineness 1500D, melting point 330℃, homemade;

[0057] Liquid crystal fiber 7: fineness 1500D, melting point 370℃, homemade;

[0058] Liquid crystal fiber 8: fineness 200D, melting point 350℃, homemade;

[0059] Liquid crystal fiber 9: fineness 5000D, melting point 350℃, homemade;

[0060] Liquid crystal fiber 10: fineness 1500D, melting point 310℃, homemade;

[0061] The preparation method of liquid crystal fiber is as follows:

[0062] Liquid crystal resin was prepared by melt spinning, and then heat-treated at 30°C below the melting point for 18 hours (annealed at 250°C for 10 hours) to obtain liquid crystal fibers of different finenesses; liquid crystal fibers of different finenesses were obtained by adjusting the number of spinnerets, wherein the liquid crystal resin used in liquid crystal fibers 1 to 5 and liquid crystal fibers 8 to 9 was type I resin, Vicryst R8400 NC001 (purchased from Zhuhai Wantong Special Engineering Plastics), the liquid crystal resin used in liquid crystal fiber 6 was type I resin, Vicryst R8500 NC003 (purchased from Zhuhai Wantong Special Engineering Plastics); the liquid crystal resin used in liquid crystal fiber 7 was type I resin, Vicryst R8200 NC005 (purchased from Zhuhai Wantong Special Engineering Plastics); and the liquid crystal resin used in liquid crystal fiber 10 was type II resin, Vicryst R8000 NC006 (purchased from Zhuhai Wantong Special Engineering Plastics).

[0063] White pigment:

[0064] White pigment 1: titanium oxide, R-105, average particle size 0.31 μm, commercially available;

[0065] White pigment 2: titanium oxide, 696, average particle size 0.12 μm, Koster;

[0066] Additives:

[0067] Antioxidant: Antioxidant 1098; Lubricant: Silicone lubricant, MB50-002; Weathering agent: S-EED FF, commercially available; The same raw materials were used in the parallel experiments of the embodiment and the comparative example.

[0068] Examples 1 to 14 and Comparative Examples 1 to 5

[0069] The liquid crystal fiber reinforced polyester resin compositions described in Examples 1 to 14 and Comparative Examples 1 to 5 were prepared according to the formulations in Tables 1 to 2 using the following preparation method:

[0070] PCT resin, white pigment, additives and liquid crystal fiber are added to a high-speed mixer in proportion and mixed evenly, and then put into a twin-screw extruder for melt blending and extrusion granulation to obtain a liquid crystal fiber reinforced polyester resin composition; the temperature of the extrusion granulation is as follows: the temperature of the first zone is 300°C; the temperature of the second zone is 310°C; the temperature of the third and fourth zones is 320°C; the temperature of the fifth zone is 330°C; the temperature of the sixth and seventh zones is 310°C; the temperature of the eighth zone is 300°C; the temperature of the ninth zone is 280°C; and the temperature of the tenth zone is 290°C.

[0071] Table 1 Amount of each component in the liquid crystal fiber reinforced polyester resin composition in Examples 1 to 8 (Unit: parts by weight)

[0072] Table 2 Amount of each component in the liquid crystal fiber reinforced polyester resin composition in Examples 9 to 14 and Comparative Examples 1 to 5 (Unit: parts by weight)

[0073] Performance Testing

[0074] 1. Test method

[0075] (1) Bending strength test: The liquid crystal fiber reinforced polyester resin compositions prepared in the above examples and comparative examples were measured for their bending strength according to the standard ISO 178-2019, and recorded as the initial bending strength; the samples were then subjected to three SMTs and the bending strength was measured again according to the same method, and recorded as the bending strength after SMT;

[0076] (2) Reflectivity test: The reflectivity of the liquid crystal fiber reinforced polyester resin composition prepared in the above examples and comparative examples was measured at a wavelength of 460 nm using a Minolta 3600D spectrophotometer according to the CIE Lab color difference evaluation standard, and recorded as the initial reflectivity; then, the sample was subjected to three SMTs and the reflectivity was measured again using the same method, and recorded as the post-SMT reflectivity.

[0077] 2. Test results

[0078] The test results of the flexural strength and reflectivity properties of the liquid crystal fiber reinforced polyester resin compositions prepared in the above examples and comparative examples are shown in Table 3.

[0079] Table 3 Test results of various embodiments and comparative examples

[0080] As can be seen from Table 3, the liquid crystal fiber-reinforced polyester resin composition prepared in the present invention has good strength and reflectivity, and the strength and reflectivity are still high after SMT. Specifically, the initial bending strength is not less than 85 MPa, the bending strength after SMT is not less than 75 MPa, and the bending strength retention rate is not less than 85%; the initial reflectivity is not less than 92%, the reflectivity after SMT is not less than 88%, and the reflectivity retention rate is not less than 94%.

[0081] It can be seen from Examples 1 to 5 that when the fineness of the liquid crystal fiber is adjusted to 1200-2000D, the obtained liquid crystal fiber reinforced polyester resin composition has better comprehensive performance and has a higher bending strength retention rate while ensuring a higher reflectivity retention rate.

[0082] It can be seen from Comparative Example 1 that if the fineness of the liquid crystal fiber used is too low, it cannot play a good reinforcing role and the bending strength of the prepared composition is low.

[0083] As can be seen from Comparative Example 2, excessively fine liquid crystal fibers can cause difficulty dispersing within the system, leading to excessive shear heating during processing and preventing extrusion molding. This results in decreased reflectivity and poor yellowing resistance in the resulting liquid crystal fiber-reinforced polyester resin composition, resulting in significantly lower reflectivity after SMT.

[0084] It can be seen from Comparative Example 3 that if too little liquid crystal fiber is added, the strength cannot be enhanced, and the flexural strength of the obtained liquid crystal fiber-reinforced polyester resin composition is low.

[0085] It can be seen from Comparative Example 4 that if too much liquid crystal fiber is added, it will cause difficulty in dispersing it in the system and processing it, resulting in a decrease in the reflectivity of the liquid crystal fiber-reinforced polyester resin composition and poor yellowing resistance, which leads to significantly poor reflectivity after SMT.

[0086] It can be seen from Comparative Example 5 that if the melting point of the liquid crystal fiber used is too low, the performance of the obtained liquid crystal fiber reinforced polyester resin composition is significantly worse than that of the embodiment.

[0087] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A liquid crystal fiber reinforced polyester resin composition, characterized in that The composition comprises the following components calculated in parts by weight: Wherein, the fineness of the liquid crystal fiber is 900-3200D; the melting point of the liquid crystal fiber is ≥320°C.

2. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The fineness of the liquid crystal fiber is 1000-3000D.

3. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The average particle size of the white pigment is 0.1 to 0.5 μm.

4. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The melting point of the liquid crystal fiber is 340-360°C.

5. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The composition comprises the following components calculated in parts by weight:

6. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The intrinsic viscosity of the PCT resin is 0.6 to 0.

8.

7. The liquid crystal fiber reinforced polyester resin composition according to claim 1, characterized in that: The auxiliary agent includes one or more of an antioxidant, a lubricant or a weathering agent.

8. A method for preparing the liquid crystal fiber reinforced polyester resin composition according to any one of claims 1 to 7, characterized in that: The steps include: The PCT resin, white pigment, auxiliary agent and liquid crystal fiber are mixed evenly, and then melt-blended and extruded into granules in an extruder to obtain a liquid crystal fiber reinforced polyester resin composition.

9. The preparation method according to claim 8, characterized in that: The temperature of the extrusion granulation is 270-340°C.

10. Use of the liquid crystal fiber reinforced polyester resin composition according to any one of claims 1 to 7 in preparing LED bracket materials.

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