Preparation method of low-dielectric-constant high-heat-resistance LCP composite material for communication equipment

Abstract

The invention discloses a preparation method of a low-dielectric-constant and high-heat-resistance LCP composite material for communication equipment. The preparation method sequentially comprises the following steps: S1, preparing the following raw materials in parts by mass: 50-80 parts of a liquid crystal polymer, 1-10 parts of glass fibers, 10-20 parts of inorganic fibers, 0-2 parts of a surface treating agent and 0.5-2 parts of a processing aid; S2, treating the surfaces of the inorganic fibers by adopting the surface treating agent; s3, mixing the liquid crystal polymer and the processing aid in a rotary mixer in proportion, and feeding from a main feed opening of the double-screw extruder; the preparation method comprises the following steps: mixing glass fibers and inorganic fibers according to a certain adding ratio by a mixer, feeding from a side feeding port of an extruder by a screw feeder, and carrying out melt mixing extrusion granulation. According to the invention, the defect that the LCP is easy to bubble after being involved in water vapor is overcome, the use temperature of the material is increased, and the application range of the LCP in a low-dielectric material in mobile phone components is widened.

Description

Technical Field

[0001] The invention relates to the field of engineering plastic composite materials, and in particular to a method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment. Background Art

[0002] With the rapid development of mobile phone hardware, the requirements for electronic transmission speed and loss of internal communication device materials have also been further improved. Compared with traditional 4G and other communication technologies, 5G communication technology access working devices must meet the three basic performance requirements of full spectrum access, high frequency band and even millimeter wave transmission, and ultra-high broadband transmission. At present, the materials used in 5G mobile phone antennas are mainly LCP (liquid crystal polymer) and MPI (modified polyimide). Liquid crystal polymer (LCP) has excellent processing fluidity, mechanical strength, thermal stability and low dielectric constant. There are more and more studies on LCP as a component of polymer alloys.

[0003] In order to meet the market demand for high heat resistance and low dielectric properties of communication equipment components, the present invention aims to prepare a low dielectric and high heat resistance LCP composite material, which has excellent heat resistance, low dielectric properties and molding processability.

[0004] Since LCP has a low dielectric constant and dielectric loss, there have been many studies on low dielectric materials based on LCP. However, LCP is prone to blistering due to the fact that it is easy to be drawn into water vapor during molding. An important method for preparing LCP low dielectric constant and high heat resistance materials is to blend LCP surface treatment with functional fillers.

[0005] CN116162361A relates to a method for preparing a low dielectric and high heat-resistant LCP composite material, wherein the hollow metal oxide is obtained by coating the metal oxide on the surface of POSS. The hollow metal oxide, glass fiber 5-30%, antioxidant 0-2%, and LCP resin are blended to obtain the composite material. However, the filling of metal oxide and glass fiber still fails to solve the disadvantage that the LCP material is easily involved in water vapor and generates bubbles during molding. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment. The method adopts LCP material with a low dielectric constant as a substrate, and performs surface treatment on mineral fiber through a silane coupling agent. The surface of the filled LCP has hydrophobicity, and then an appropriate amount of glass fiber is filled to increase the thermal deformation temperature. This method improves the disadvantage of LCP being easy to foam when it is involved in water vapor, and increases the use temperature of the material, thereby broadening the application of LCP as a low dielectric material in mobile phone components.

[0007] To achieve the above object, the present invention provides the following technical solutions.

[0008] The present application embodiment discloses a method for preparing a low dielectric constant and high heat resistance LCP composite material for communication equipment, which comprises the following steps in sequence:

[0009] S1 Prepare the following raw materials by mass: 50-80 parts of liquid crystal polymer, 1-10 parts of glass fiber, 10-20 parts of inorganic fiber, 0-2 parts of surface treatment agent, and 0.5-2 parts of processing aid.

[0010] S2 treating the surface of the inorganic fiber with the surface treatment agent, wherein the surface treatment agent is at least one of KH550, KH560 and KH580, and the dispersant is anhydrous methanol, and the inorganic fiber, coupling agent and dispersant are fully mixed according to a certain addition ratio and then dried to obtain a surface modified filler;

[0011] S3: Liquid crystal polymer and processing aid are mixed in a rotary mixer according to a certain proportion, and then fed into the main feed port of the twin-screw extruder; glass fiber and inorganic fiber are mixed in a mixer according to a certain addition proportion, and then fed into the side feed port of the extruder by a screw feeder to perform melt mixing, extrusion and granulation;

[0012] S4 The rotary mixer used in step S3 has a rotation speed of 60-120 rpm, a mixing time of 5-10 min, a twin-screw extruder with an output of 100-200 kg / h, a rotation speed of 200-400 rpm, a barrel temperature of 330±20°C, a die temperature of 340±10°C, and a vacuum section extraction pressure of -0.08±0.02 MPa.

[0013] Preferably, in the method for preparing the low dielectric constant and high heat-resistant LCP composite material for communication equipment, the liquid crystal polymer is an aromatic polyester and polyester amide having a melting point of 300-360°C.

[0014] Preferably, in the above-mentioned method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment, the inorganic fiber comprises at least one of surface-treated wollastonite fiber and potassium titanate fiber.

[0015] Preferably, in the above-mentioned method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment, the processing aid includes a lubricant and an antioxidant, the lubricant includes at least one of silicone powder, pentaerythritol stearate, calcium stearate and zinc stearate, and the antioxidant includes at least one of hindered phenols, phosphites and thioesters.

[0016] The present invention adopts LCP, a material with a low dielectric constant, as a substrate, and performs surface treatment on mineral fibers by using a silane coupling agent. The surface of the filled LCP has hydrophobicity, and then an appropriate amount of glass fiber is filled to increase the thermal deformation temperature. This method improves the disadvantage of LCP being prone to bubbling when it is drawn into water vapor, and increases the use temperature of the material, thereby broadening the application of LCP as a low dielectric material in mobile phone components. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1:

[0019] Step (1): First, 1 part of KH580 is uniformly dispersed in 10 parts of anhydrous methanol according to the volume fraction to prepare a coupling agent dispersion, and then the coupling agent is added at a rate of 1wt% and sprayed uniformly into a mixing reaction kettle containing boron nitride powder, stirring while spraying to ensure that the coupling agent is uniformly dispersed in the powder, and the powder is dried after continued stirring for 10 minutes to obtain a surface-treated powder. The low dielectric constant glass fiber is surface treated in the same way.

[0020] Step (2): After mixing 80 parts of LCP resin, 1 part of silicone powder and 0.5 parts of phosphite in a rotary mixer, feed them from the main feed port of a twin-screw extruder; after mixing 10 parts of wollastonite fiber and 8.5 parts of glass fiber in a rotary mixer, feed them from the side feed port of the extruder via a screw feeder to melt-mix and extrude granulate. The rotary mixer used in step (2) has a rotation speed of 60 rpm and a mixing time of 10 min. The twin-screw extruder has an output of 150 kg / h, a rotation speed of 250 rpm, a barrel temperature of 330°C, a die temperature of 340°C, and a vacuum section extraction pressure of -0.1 MPa.

[0021] Embodiment 2:

[0022] Step (1): First, 1 part of KH580 is uniformly dispersed in 10 parts of anhydrous methanol according to the volume fraction to prepare a coupling agent dispersion, and then the coupling agent is added at a rate of 1wt% and sprayed uniformly into a mixing reaction kettle containing boron nitride powder, stirring while spraying to ensure that the coupling agent is uniformly dispersed in the powder, and the powder is dried after continued stirring for 10 minutes to obtain a surface-treated powder. The low dielectric constant glass fiber is surface treated in the same way.

[0023] Step (2): After mixing 80 parts of LCP resin, 1 part of silicone powder and 0.5 parts of phosphite in a rotary mixer, feed them from the main feed port of a twin-screw extruder; after mixing 10 parts of potassium titanate fiber and 8.5 parts of glass fiber in a rotary mixer, feed them from the side feed port of the extruder via a screw feeder for melt mixing, extrusion and granulation. The rotary mixer used in step (2) has a rotation speed of 60 rpm and a mixing time of 10 min. The twin-screw extruder has an output of 150 kg / h, a rotation speed of 250 rpm, a barrel temperature of 330°C, a die temperature of 340°C, and a vacuum section extraction pressure of -0.1 MPa.

[0024] The composite material prepared according to the present invention has the following properties: dielectric constant, dielectric loss, and heat deformation temperature all exceed the typical comparative example (LCP / 15% low dielectric constant glass fiber).

[0025] project Example 1 Example 2 Comparative Example Dielectric constant 1MHz 2.3 2.1 3.3 Dielectric loss 1MHz 0.018 0.019 0.024 Tensile strength MPa 130 130 135 Bending strength MPa 165 170 160 HDT 1.8mpa (℃) 270 270 265

[0026] This implementation mode is only an exemplary description of this patent and does not limit its protection scope. Personnel in this field may also make partial changes to it. As long as it does not exceed the spirit of this patent, it shall be regarded as an equivalent replacement of this patent and shall be within the protection scope of this patent.

Claims

1. A method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment, characterized in that: The steps are as follows: S1 Prepare the following raw materials by mass: 50-80 parts of liquid crystal polymer, 1-10 parts of glass fiber, 10-20 parts of inorganic fiber, 0-2 parts of surface treatment agent, and 0.5-2 parts of processing aid. S2 treating the surface of the inorganic fiber with the surface treatment agent, wherein the surface treatment agent is at least one of KH550, KH560 and KH580, and the dispersant is anhydrous methanol, and the inorganic fiber, coupling agent and dispersant are fully mixed according to a certain addition ratio and then dried to obtain a surface modified filler; S3: Liquid crystal polymer and processing aid are mixed in a rotary mixer according to a certain proportion, and then fed into the main feed port of the twin-screw extruder; glass fiber and inorganic fiber are mixed in a mixer according to a certain addition proportion, and then fed into the side feed port of the extruder by a screw feeder to perform melt mixing, extrusion and granulation; S4 The rotary mixer used in step S3 has a rotation speed of 60-120 rpm, a mixing time of 5-10 min, a twin-screw extruder with an output of 100-200 kg / h, a rotation speed of 200-400 rpm, a barrel temperature of 330±20°C, a die temperature of 340±10°C, and a vacuum section extraction pressure of -0.08±0.02 MPa.

2. The method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment according to claim 1, characterized in that: The liquid crystal polymer is an aromatic polyester or polyester amide having a melting point of 300-360°C.

3. The method for preparing the low dielectric constant and high heat-resistant LCP composite material for communication equipment according to claim 1, characterized in that: The inorganic fiber includes at least one of surface-treated wollastonite fiber and potassium titanate fiber.

4. The method for preparing a low dielectric constant and high heat-resistant LCP composite material for communication equipment according to claim 1, characterized in that: The processing aid includes a lubricant and an antioxidant. The lubricant includes at least one of silicone powder, pentaerythritol stearate, calcium stearate and zinc stearate. The antioxidant includes at least one of hindered phenol, phosphite and thioester.