CN114133706B

CN114133706B - PBT composite material and preparation method and application thereof

Info

Publication number: CN114133706B
Application number: CN202111269919.7A
Authority: CN
Inventors: 龚德君; 陈平绪; 叶南飚; 付学俊
Original assignee: Kingfa Science and Technology Co Ltd
Current assignee: Kingfa Science and Technology Co Ltd
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-06-27
Anticipated expiration: 2041-10-29
Also published as: CN114133706A

Abstract

The invention discloses a PBT composite material, which comprises the following components in parts by weight: 60 parts of PBT resin; 10-40 parts of alkali-free glass fiber; 0.1-10 parts of polyester toughening agent; 20-40 parts of wave absorber; wherein the wave absorber is polyacrylonitrile-based carbon fiber in weight ratio: barium titanate: carbon nanotube= (2-15): (2-12): 1. on one hand, the PBT composite material with high wave absorbability can be obtained through the polyacrylonitrile-based carbon fiber/barium titanate/carbon nanotube compound wave absorber and under the promotion and dispersion actions of alkali-free glass fiber and polyester toughening agent; on the other hand, the existence of the polyester toughening agent can effectively improve the defect of floating fiber.

Description

PBT composite material and preparation method and application thereof

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a PBT composite material, a preparation method and application thereof.

Background

With the continuous development of 5G technology, the demand of reinforced PBT materials in the fields of electromagnetic wave shielding and the like is increasing. In the process of designing and improving electromagnetic compatibility, common methods for inhibiting electromagnetic interference include grounding, shielding, filtering and the like. In solving the problem of high-frequency electromagnetic interference, the completely shielding solution is increasingly unable to meet the requirements. Because the arrangement of ports and the requirements of ventilation, windows and the like in many devices make it impossible for practical shielding methods to form a full shielding cage like a faraday cage, port size is a big threat to the high frequency of the devices. In addition, after the device is effectively shielded, although the external interference is solved, the electromagnetic wave interference still exists in the shielding system, even the interference is aggravated because of shielding, and even the device is caused to not work normally. These are all problems with shielding, and because of these problems, wave absorbing materials have great utility. The wave absorbing material is a material capable of effectively absorbing incident electromagnetic waves and making them scatter and attenuate, and can convert the incident electromagnetic waves into heat energy or other energy forms by various loss mechanisms of the material so as to achieve the purpose of absorbing the electromagnetic waves. Unlike shielding solutions, their effectiveness is in reducing the number of interfering electromagnetic waves. With the popularization of unmanned technology in the future, higher requirements are put on the wave absorbing performance of materials in Advanced Driving Assistance System (ADAS) radar material solutions.

The basic conditions for the material to absorb electromagnetic waves are: when electromagnetic waves are incident on the material, the electromagnetic waves can enter the material to the greatest extent without being reflected as far as possible, namely, the material is required to meet impedance matching; furthermore, electromagnetic wave energy entering the material is rapidly attenuated almost entirely, i.e. the material is required to meet electromagnetic losses, which in turn include: resistive loss, dielectric loss, and magnetic loss. The main design idea of the PBT wave-absorbing material is to add a wave-absorbing agent, and the traditional wave-absorbing material cannot achieve both minimum reflection and maximum absorption.

Disclosure of Invention

The invention aims to provide a PBT composite material, which has the advantages of low reflection and high wave absorption.

The invention is realized by the following technical scheme:

the PBT composite material comprises the following components in parts by weight:

60 parts of PBT resin;

10-40 parts of alkali-free glass fiber;

0.1-10 parts of polyester toughening agent;

20-40 parts of wave absorber;

wherein the wave absorber is polyacrylonitrile-based carbon fiber in weight ratio: barium titanate: carbon nanotube= (2-15): (2-12): 1.

preferably, the polyacrylonitrile-based carbon fiber comprises the following components in percentage by weight: barium titanate: carbon nanotube= (6-11): (5-8): 1.

the polyester toughening agent is at least one selected from ethylene-acrylic ester-glycidyl methacrylate terpolymer, glycidyl methacrylate grafted ethylene-octene copolymer, ethylene-vinyl acetate copolymer and ethylene-methyl acrylate binary copolymer; preferably, the polyester-based toughening agent is selected from glycidyl methacrylate grafted ethylene-octene copolymers.

The PBT resin is not particularly limited, and the technical effects of the invention can be achieved by the PBT resin used in general engineering. The typical PBT resin has an intrinsic viscosity in the range of 0.7-1.3dL/g, under test conditions of 25 ℃. The test method of the intrinsic viscosity of the PBT resin comprises the following steps: the intrinsic viscosity of the PBT resin disclosed by the invention is detected by a GB/T14190-2017 method.

The carbon nano tube is at least one selected from a single-arm carbon nano tube and a multi-arm carbon nano tube; multi-arm carbon nanotubes are preferred. The research shows that the multi-arm carbon nano tube has more complex structure, is easier to form bridging effect when dispersed in the material, and achieves better conductive effect under lower dosage.

Preferably, the length of the polyacrylonitrile-based carbon fiber is in the range of 2-8 mm; the particle diameter D50 of the barium titanate is 1.0-3.0 microns.

Preferably, the polyacrylonitrile-based carbon fiber, the barium titanate and the carbon nano tube are treated by 0.01-2 parts by weight of epoxy silane coupling agent, wherein the epoxy silane coupling agent is at least one selected from gamma-glycidol ether oxypropyl trimethoxy silane, 2- (3, 4-epoxycyclohexane) ethyl trimethoxy silane and 3- [ (2, 3) -epoxypropoxy ] propyl methyl dimethoxy silane.

Whether a proper amount of auxiliary agent is added or not can be selected according to actual conditions, and the auxiliary agent can be 0-2 parts by weight, wherein the auxiliary agent is one or more selected from an antioxidant and a lubricant. The lubricant is one or more of aliphatic carboxylic ester, erucamide, ethylene bis stearamide, montan esters, polyethylene wax and oxidized polyethylene wax; the antioxidant is one or more of hindered phenol antioxidants, phosphite antioxidants and organic sulfur antioxidants.

The preparation method of the PBT composite material comprises the following steps: firstly, treating barium titanate, polyacrylonitrile-based carbon fiber and carbon nano tube by an epoxy silane coupling agent, and then uniformly mixing PBT resin, barium titanate, polyacrylonitrile-based carbon fiber and carbon nano tube according to a proportion by a high-speed stirring mixer; the mixed material is sent into a double-screw extruder, fully melted, plasticized, kneaded and mixed under the conveying and shearing actions of the double-screw extruder, alkali-free glass fiber is fed from side, extruded by a machine head, bracing, cooled, pelletized and dried, and the PBT composite material is obtained; the temperature of each section of screw rod of the double screw extruder from the feed inlet to the machine head is 220-230 ℃, 230-240 ℃, 203-240 ℃, 240-250 ℃, 250-260 ℃, 240-250 ℃, 230-240 ℃ and the screw rod rotating speed is 250-400 rpm.

The application of the PBT composite material is used for preparing a radar antenna housing.

The invention has the following beneficial effects

1. According to the invention, the PBT composite material has a good wave-absorbing foundation by the polyacrylonitrile-based carbon fiber/barium titanate/carbon nanotube compound wave-absorbing agent: the collocation of the carbon nano tube and the carbon fiber controls the conductivity of the material in an antistatic area, and the material meets the impedance matching, so that on one hand, reflection is reduced, on the other hand, electromagnetic waves enter the material to the maximum extent, and meanwhile, the carbon nano tube and the carbon fiber can effectively improve resistance loss and barium titanate can effectively improve dielectric loss, and the two different loss mechanisms cooperate to enable the electromagnetic waves to dissipate to the maximum extent inside to achieve a wave absorbing effect.

2. Under the promotion and dispersion action of alkali-free glass fiber and polyester toughening agent, the dispersion of the compound wave absorber can be improved, and the wave absorbing action of the compound wave absorber can be fully exerted.

3. Compared with other types of toughening agents, the polyester toughening agent can also obviously improve the dispersion of alkali-free glass fibers and wave absorbing agents, improve the defect of floating fibers and further improve the microwave absorbability.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.

The raw materials used in the examples and comparative examples are as follows:

PBT resin A: PBT 1200-211M, taiwan vinca, with an intrinsic viscosity of 0.8dL/g and a test condition of 25 ℃; PBT resin B: PBT GX111, instrumentation chemical fiber, intrinsic viscosity 0.7 dl/g, test condition 25 ℃;

multi-arm carbon nanotubes: LUCAN CP1002M, LG chemistry;

single-arm carbon nanotubes: TUBALL single-arm carbon nanotubes, aucky Sierre trade (Shenzhen Co., ltd.);

graphite alkyne: department of chemistry of the Chinese sciences;

c60: fullerene C60, shanghai Haohong biological medicine technologies Co., ltd;

nanoscale carbon black: cabot corporation;

graphene: high conductivity graphene powder, german catene carbon technologies limited;

polyacrylonitrile-based carbon fiber a: the length is within 2-8mm, and is available from Toli Japan;

polyacrylonitrile-based carbon fiber B: the length is within 1-2mm, and is available from Toli Japan;

polyacrylonitrile-based carbon fiber C: the length is in the range of 8-20mm, and is available from Toli Corp;

pitch-based carbon fiber: the length is in the range of 4-10mm, manufactured by Osaka gas chemical company, japan;

glass fiber a: alkali-free glass fiber, ECS13-4.5-534A, boulder group;

glass fiber B: medium alkali glass fiber, CR21-2400, tuhu Bai Yunbo fiber Co., ltd;

barium titanate a: d50 =1.2 microns;

barium titanate B: d50 =3.0 microns;

barium titanate C: d50 =0.5 microns;

barium titanate D: d50 =5 microns;

barium titanate is purchased from Shanghai classical, and barium titanate with different particle sizes is obtained through screening.

Coupling agent A: gamma-glycidoxypropyl trimethoxysilane, JH-0187, jing Zhoujiang, han fine chemical industry;

coupling agent B:3- [ (2, 3) -glycidoxy ] propyl methyl dimethoxy silane, CG-186, nanjing Chen's organosilicon;

coupling agent C:2- (3, 4-epoxycyclohexane) ethyl trimethoxy silane, CG-561, nanjing Chen organic silicon.

Polyester toughening agent A: ethylene-acrylate-glycidyl methacrylate terpolymer, PTW, duPont;

polyester toughening agent B: glycidyl methacrylate grafted ethylene-octene copolymer, SOG-03, preferably Yi Rong;

polyester-based toughening agent C: ethylene-methyl acrylate copolymer, ELVALOY AC 1125, dupont;

polyester toughening agent D: ethylene-vinyl acetate copolymer, EVA28-25, france Acomat;

other toughening agents a: POE 58750, dow, usa;

other toughening agents B: MBS toughening agent, M-521, japanese Brillouin.

And (3) a lubricant: ethylene bis stearamide, commercially available.

According to the preparation method of the PBT composite material of the embodiment and the comparative example, if the formula contains the coupling agent, firstly, barium titanate, polyacrylonitrile-based carbon fiber and carbon nano tube are treated by the epoxy silane coupling agent, and then the PBT resin, the wave absorber and the polyester toughening agent are uniformly mixed by a high-speed stirring mixer according to the proportion; the mixed material is sent into a double-screw extruder, fully melted, plasticized, kneaded and mixed under the conveying and shearing actions of the double-screw extruder, alkali-free glass fiber is fed from side, extruded by a machine head, bracing, cooled, pelletized and dried, and the PBT composite material is obtained; the temperature of each section of screw rod of the double screw extruder from the feed inlet to the machine head is 220-230 ℃, 230-240 ℃, 203-240 ℃, 240-250 ℃, 250-260 ℃, 240-250 ℃, 230-240 ℃ and the screw rod rotating speed is 300rpm.

The testing method comprises the following steps:

(1) Reflection and wave absorption properties: using a free space method, adopting GJB 7954-2012 (radar absorbing material transmittance test method) to test, wherein the specific test frequency is 77GHz, and the test sample size is 3.0 x 100mm square plate;

(2) Surface floating fiber: observing the floating fiber degree of the surface of the square plate by a microscope, wherein the floating fiber degree is classified into 1-4 grades, and the 1 grade is almost free of floating fiber; the level 2 is slightly floating fiber, but the surface smoothness is not affected; the level 3 is that the floating fiber is obvious, and the surface smoothness is slightly affected; the level 4 is more floating fibers, which affects the surface smoothness.

Table 1: examples 1-7 PBT composite Material Each component content (parts by weight) and test results

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7
								PBT resin A	60		60	60	60	60	60
PBT resin B		60
								Glass fiber A	20	20	20	40	10	20	20
Polyacrylonitrile-based carbon fiber A	16	16	13.33	13.33	20	12	15
								Barium titanate A	12	12	5	10	15	12	12
Multi-arm carbon nanotubes	2	2	1.67	1.67	2.5	6	3
								Polyester toughening agent A	2	2	1	10	4	2	2
Coupling agent A	0.5	0.5	1			0.5	0.5
								Coupling agent B				0.5
Coupling agent C					0.1
								Microwave reflectance%	20	18	25	18	24	27	26
Microwave absorptivity%	65	63	51	50	62	57	56
								Surface float fiber, grade	1	1	1	2	1	1	1

Table 2: examples 8-14PBT composite Material Each component content (parts by weight) and test results

	Example 8	Example 9	Example 10	Example 11	Example 12	Example 13	Example 14
								PBT resin A	60	60	60	60	60	60	60
Glass fiber A	20	20	20	20	20	20	20
								Polyacrylonitrile-based carbon fiber A	5.61	23.7	15.6	15	16.5	19.36	16
Barium titanate A	22.44	4.74	13	12.5	12	8.8	12
								Multi-arm carbon nanotubes	1.87	1.58	1.30	2.5	1.5	1.76	2
Polyester toughening agent A	2	2	2	2	2	2	2
								Coupling agent A	0.5	0.5	0.5	0.5	0.5	0.5	0.5
Microwave reflectance%	10	24	18	22	19	21	20
								Microwave absorptivity%	50	55	55	64	60	62	65
Surface float fiber, grade	1	1	1	1	1	1	1

As can be seen from examples 6 to 14, polyacrylonitrile-based carbon fibers are preferable: barium titanate: carbon nanotube= (6-11): (5-8): 1, the microwave absorptivity is higher, and the difference between the microwave absorptivity and the microwave reflectivity is larger. Specifically, as can be seen from example 8, although when polyacrylonitrile-based carbon fiber: barium titanate: carbon nanotube = 3:12:1, although the microwave reflectivity is the lowest, the microwave absorptivity is low, and the applicability is not as good as the preferable proportioning range.

Table 3: examples 15-22PBT composite Material Each component content (parts by weight) and test results

	Example 15	Example 16	Example 17	Example 18	Example 19	Example 20	Example 21	Example 22	Example 23
										PBT resin A	60	60	60	60	60	60	60	60	60
Glass fiber A	20	20	20	20	20	20	20	20	20
										Polyacrylonitrile-based carbon fiber A			15	15	15	15	15	15	15
Polyacrylonitrile-based carbon fiber B	15
										Polyacrylonitrile-based carbon fiber C		15
Barium titanate A	12.5	12.5				12.5	12.5	12.5	12.5
										Barium titanate B			12.5
Barium titanate C				12.5
										Barium titanate D					12.5
Multi-arm carbon nanotubes	2.5	2.5	2.5	2.5	2.5		2.5	2.5	2.5
										Single-arm carbon nanotube						2.5
Polyester toughening agent A	2	2	2	2	2	2
										Polyester toughening agent B							2
Polyester toughening agent C								2
										Polyester toughening agent D									2
Coupling agent A	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
										Microwave reflectance%	25	28	21	23	19	22	18	20	24
Microwave absorptivity%	55	59	60	56	52	56	63	62	60
										Surface float fiber, grade	1	1	1	2	2	1	1	1	1

As is clear from examples 11 and 15/16, the length of the polyacrylonitrile-based carbon fiber is preferably in the range of 2 to 8mm.

As is clear from examples 11 and 17 to 19, the barium titanate particle size d50=1 to 3 μm is preferable.

As is clear from examples 11 and 20, the multi-walled nanotubes are preferable.

As is clear from examples 11 and 21/22/23, the polyester-based toughening agent is preferably a glycidyl methacrylate grafted ethylene-octene copolymer.

Table 4: example 24 PBT composite Material Each component content (weight parts) and test results

	Example 24
		PBT resin A	60
Glass fiber A	20
		Polyacrylonitrile-based carbon fiber A	16
Barium titanate A	12
		Multi-arm carbon nanotubes	2
Polyester toughening agent A	2
		Coupling agent A	0.5
Lubricant	0.2
		Microwave reflectance%	20
Microwave absorptivity%	66
		Surface float fiber, grade	1

Table 5: comparative example PBT composite Material content (parts by weight) and test results

	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5	Comparative example 6	Comparative example 7	Comparative example 8
									PBT resin A	60	60	60	60	60	60	60	60
Glass fiber A		20		20	20	20	20	20
									Glass fiber B	20
Polyacrylonitrile-based carbon fiber A	15			15	15	15	15	15
									Pitch-based carbon fiber		15	15
Barium titanate A	12.5	12.5	12.5	12.5	12.5	12.5	12.5	12.5
									Multi-arm carbon nanotubes	2.5	2.5	2.5				2.5	2.5
Graphite alkyne				2.5
									C60					2.5
Nanoscale carbon black						2.5
									Polyester toughening agent A	2	2	2	2	2	2
Other toughening agent A							2
									Other toughening agent B								2
Coupling agent A	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
									Microwave reflectance%	20	15	18	16	15	17	31	38
Microwave absorptivity%	36	38	32	30	35	28	60	57
									Surface float fiber, grade	3	2	1	2	2	2	2	2

As is clear from comparative example 1, the medium alkali glass fiber cannot achieve the object of the present invention.

As is clear from comparative example 2/3, other types of carbon fibers cannot achieve the technical effects of high microwave absorption and low reflection at the same time.

As is clear from comparative examples 4 to 6, the conventional conductive carbon materials such as graphite alkyne, C60, nano-scale carbon black and the like cannot achieve the object of the present invention.

As is clear from examples 11 and comparative examples 7/8, the use of other types of toughening agents had poor dispersion of glass fibers and wave-absorbing agents, high microwave reflectivity, and increased surface float.

Claims

1. The PBT composite material is characterized by comprising the following components in parts by weight:

60 parts of PBT resin;

10-40 parts of alkali-free glass fiber;

0.1-10 parts of polyester toughening agent;

20-40 parts of wave absorber;

wherein the wave absorber is polyacrylonitrile-based carbon fiber in weight ratio: barium titanate: carbon nanotube= (2-15): (2-12): 1, a step of;

the polyester toughening agent is at least one selected from ethylene-acrylic ester-glycidyl methacrylate terpolymer, glycidyl methacrylate grafted ethylene-octene copolymer, ethylene-vinyl acetate copolymer and ethylene-methyl acrylate binary copolymer;

the carbon nano tube is at least one selected from a single-arm carbon nano tube and a multi-arm carbon nano tube;

in the resin matrix, the length of the polyacrylonitrile-based carbon fiber is in the range of 2-8mm, and the particle diameter D50 of the barium titanate is 1.0-3.0 micrometers.

2. The PBT composite material according to claim 1, wherein the polyacrylonitrile-based carbon fiber is in weight ratio: barium titanate: carbon nanotube= (6-11): (5-8): 1.

3. the PBT composite material of claim 1, wherein the polyester-based toughening agent is selected from glycidyl methacrylate grafted ethylene-octene copolymers.

4. The PBT composite material of claim 1, wherein the PBT resin has an intrinsic viscosity in the range of 0.7 to 1.3dL/g at 25 ℃.

5. The PBT composite material according to claim 1, wherein the carbon nanotubes are selected from the group consisting of multi-arm carbon nanotubes.

6. The PBT composite material according to claim 1, wherein the polyacrylonitrile-based carbon fiber, the barium titanate and the carbon nanotube are treated with 0.01-2 parts by weight of an epoxy silane coupling agent, wherein the epoxy silane coupling agent is at least one selected from gamma-glycidoxypropyl trimethoxysilane, 2- (3, 4-epoxycyclohexane) ethyl trimethoxysilane and 3- [ (2, 3) -epoxypropoxy ] propyl methyl dimethoxy silane.

7. The PBT composite material according to claim 1, further comprising one or more of an antioxidant and a lubricant in an amount of 0 to 2 parts by weight.

8. The method for preparing the PBT composite material according to any one of claims 1 to 7, comprising the steps of: firstly, treating barium titanate, polyacrylonitrile-based carbon fiber and carbon nano tube by an epoxy silane coupling agent, and then uniformly mixing PBT resin, barium titanate, polyacrylonitrile-based carbon fiber, carbon nano tube and polyester toughening agent according to a proportion by a high-speed stirring mixer; the mixed material is sent into a double-screw extruder, fully melted, plasticized, kneaded and mixed under the conveying and shearing actions of the double-screw extruder, alkali-free glass fiber is fed from side, extruded by a machine head, bracing, cooled, pelletized and dried, and the PBT composite material is obtained; the temperature of each section of screw rod of the double screw extruder from the feed inlet to the machine head is 220-230 ℃, 230-240 ℃, 203-240 ℃, 240-250 ℃, 250-260 ℃, 240-250 ℃, 230-240 ℃ and the screw rod rotating speed is 250-400 rpm.

9. Use of the PBT composite material according to any of claims 1 to 7 for the preparation of radomes.