CN114672138A

CN114672138A - Preparation process of low dielectric loss liquid crystal composite material

Info

Publication number: CN114672138A
Application number: CN202210260441.XA
Authority: CN
Inventors: 郭继光; 贺炅皓
Original assignee: Zhangjiagang Otsuka Chemical Co ltd
Current assignee: Zhangjiagang Otsuka Chemical Co ltd
Priority date: 2022-03-16
Filing date: 2022-03-16
Publication date: 2022-06-28

Abstract

The application discloses a preparation process of a low dielectric loss liquid crystal composite material, which sequentially comprises the following steps: s1, preparing the following raw materials in parts by weight: 30-50 parts of liquid crystal polymer, 5-20 parts of semi-aromatic polyimide, 15-50 parts of inorganic filler, 0.1-5 parts of glue binding promoter and 0.1-5 parts of other processing aids; s2, mixing the liquid crystal polymer, the semi-aromatic polyimide, the glue bonding promoter and other processing aids through a high-speed mixer, then adding the mixture from a main feed opening of a double-screw extruder, and adding the inorganic filler from a side feed opening of the double-screw extruder; s3, carrying out melt mixing extrusion granulation, wherein the return speed of the high-speed mixer is 60-120 rpm, the mixing time is 5-10 min, the output of the double-screw extruder is 50-200 Kg/h, the rotation speed is 100-300 rpm, the temperature of each section of the machine barrel is 330 +/-20 ℃, the head temperature is 340 +/-10 ℃, and the extraction pressure of the vacuum section is-0.08 +/-0.02 MPa. The invention adjusts the molecular orientation and improves the flexibility of molecular chains.

Description

Preparation process of low dielectric loss liquid crystal composite material

Technical Field

The invention relates to the field of composite materials, in particular to a preparation process of a low dielectric loss liquid crystal composite material.

Background

With the gradual popularization of the 5G technology, the frequency of the electromagnetic wave is higher and higher, which means that the wavelength of the electromagnetic wave is shorter, the diffraction capability is poorer, the attenuation of the electromagnetic wave in the propagation process is larger, the covering capability and the transmission signal strength of the short-frequency electromagnetic wave are greatly reduced compared with the conventional short-frequency electromagnetic wave, the dielectric performance requirement on the material aspect is higher, the liquid crystal material (LCP) has unique molecular structure and thermal behavior, the moisture absorption is small, the molecular skeleton symmetry is high, and the movement of the main chain is limited by the structure of the liquid crystal material, so that the LCP shows extremely low dielectric constant and dielectric loss in a high-frequency band, and the LCP is the preferred of many materials in the communication field of the 5G high-frequency high-speed era. At present, in the field of high-frequency and high-speed communication, the strength and the dimensional stability of a liquid crystal material are improved by adding inorganic fillers such as various titanate and titanium dioxide, hollow microspheres, low-dielectric glass fibers and the like, so that the dielectric loss of the material is further reduced.

But the molecular structure of LCP also makes the material itself have poor toughness, and because of the characteristic that LCP molecules are easy to flow to orientation, the defects of low position strength of a weld line, poor peel strength after the subsequent assembly process is combined with glue and the like exist when a complex part is injected.

Disclosure of Invention

The invention aims to provide a preparation process of a low dielectric loss liquid crystal composite material.

In order to achieve the above object, the present invention provides the following technical solutions.

The embodiment of the application discloses a preparation process of a low dielectric loss liquid crystal composite material, which sequentially comprises the following steps:

s1, preparing the following raw materials in parts by weight: 30-50 parts of liquid crystal polymer, 5-20 parts of semi-aromatic polyimide, 15-50 parts of inorganic filler, 0.1-5 parts of glue bonding promoter and 0.1-5 parts of other processing aids;

s2, mixing the liquid crystal polymer, the semi-aromatic polyimide, the glue bonding promoter and other processing aids through a high-speed mixer, then adding the mixture from a main feed opening of a double-screw extruder, and adding the inorganic filler from a side feed opening of the double-screw extruder;

s3, carrying out melt mixing extrusion granulation, wherein the return speed of the high-speed mixer is 60-120 rpm, the mixing time is 5-10 min, the discharge of the double-screw extruder is 50-200 Kg/h, the rotation speed is 100-300 rpm, the temperature of each section of the machine barrel is 330 +/-20 ℃, the head temperature is 340 +/-10 ℃, and the extraction pressure of the vacuum section is-0.08 +/-0.02 MPa.

Preferably, in the preparation process of the low dielectric loss liquid crystal composite material, the liquid crystal polymer is aromatic polyester and polyesteramide with a melting point of 300-360 ℃.

Preferably, in the preparation process of the low dielectric loss liquid crystal composite material, the semi-aromatic polyimide is one or more of PA6T/66, PA6T/6I, PA9T, PA10T, PA11T and PA 12T.

Preferably, in the preparation process of the low dielectric loss liquid crystal composite material, the inorganic filler is one or more of titanium dioxide, barium titanate, calcium titanate, strontium titanate, hollow glass microspheres and low dielectric glass fibers.

Preferably, in the preparation process of the low dielectric loss liquid crystal composite material, the glue bonding accelerator is biphenyl epoxy resin, the melting point is 80-110 ℃, and the 150 ℃ melt viscosity is 50-200 Cps.

Preferably, in the preparation process of the low dielectric loss liquid crystal composite material, the other processing aids comprise one or more of hindered amine light stabilizers, polysiloxane, polytetrafluoroethylene and aliphatic metal salt lubricants.

Compared with the prior art, the invention has the advantages that the mode of blending the liquid crystal resin and the polyamide resin is adopted, the molecular orientation is adjusted, the flexibility of a molecular chain is improved, the toughness strength of matrix resin is improved, and a small amount of glue bonding promoter is added to improve the bonding property of materials and glue.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The formulations of example 1 and example 2 are as follows (in parts by weight):

the composite material prepared by the invention has the following performance, and the toughness strength and the glue binding property are both superior to those of a comparative example (LCP/20% titanium dioxide/20% strontium titanate)

Item	Example 1	Example 2	Comparative example
				Dielectric loss (df)3GHZ	0.0025	0.0025	0.0025
Dielectric loss (df)3GHZ	175	180	190
				Glue peel strength N	90	85	55
Notched impact strength J/m	75	75	45

The present embodiments are to be considered as illustrative and not restrictive, and the scope of the patent is to be determined by the appended claims.

Claims

1. A preparation process of a low dielectric loss liquid crystal composite material is characterized by sequentially comprising the following steps of:

S1, preparing the following raw materials in parts by weight: 30-50 parts of liquid crystal polymer, 5-20 parts of semi-aromatic polyimide, 15-50 parts of inorganic filler, 0.1-5 parts of glue binding promoter and 0.1-5 parts of other processing aids;

s2, mixing the liquid crystal polymer, the semi-aromatic polyimide, the glue binding accelerant and other processing aids through a high-speed mixer, and then feeding the mixture from a main feed opening of a double-screw extruder, and feeding the inorganic filler from a side feed opening of the double-screw extruder;

s3, carrying out melt mixing extrusion granulation, wherein the return speed of the high-speed mixer is 60-120 rpm, the mixing time is 5-10 min, the output of the double-screw extruder is 50-200 Kg/h, the rotation speed is 100-300 rpm, the temperature of each section of the machine barrel is 330 +/-20 ℃, the head temperature is 340 +/-10 ℃, and the extraction pressure of the vacuum section is-0.08 +/-0.02 MPa.

2. The process for preparing the low dielectric loss liquid crystal composite material as claimed in claim 1, wherein the liquid crystal polymer is selected from aromatic polyester and polyester amide having a melting point of 300-360 ℃.

3. The preparation process of the low dielectric loss liquid crystal composite material of claim 1, wherein the semi-aromatic polyimide is one or more of PA6T/66, PA6T/6I, PA9T, PA10T, PA11T and PA 12T.

4. The preparation process of the low dielectric loss liquid crystal composite material according to claim 1, wherein the inorganic filler is one or more of titanium dioxide, barium titanate, calcium titanate, strontium titanate, hollow glass microspheres and low dielectric glass fibers.

5. The process for preparing a low dielectric loss liquid crystal composite material of claim 1, wherein the glue binding promoter is biphenyl epoxy resin with a melting point of 80-110 ℃ and a melt viscosity of 50-200 Cps at 150 ℃.

6. The process of claim 1, wherein the other processing aids comprise one or more of hindered amine light stabilizers, polysiloxanes, polytetrafluoroethylene, and aliphatic metal salt lubricants.