CN111548588A

CN111548588A - Composite material

Info

Publication number: CN111548588A
Application number: CN202010528116.8A
Authority: CN
Inventors: 高建民; 赵禹
Original assignee: Beijing Xinshiyi Energy Saving Environmental Protection Technology Co ltd
Current assignee: Beijing Xinshiyi Energy Saving Environmental Protection Technology Co ltd
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2020-08-18

Abstract

The invention belongs to the technical field of fluoroplastic composite materials, and particularly relates to a composite material which can be used in the industry of energy conservation and environmental protection. The composite material is formed by cross-linking and mixing fluoroplastic and carbon black or graphene; in the composite material, the mass ratio of the fluoroplastic is as follows: 90% -98%; the mass ratio of the carbon black or the graphene is as follows: 2 to 10 percent. The invention improves the heat conductivity coefficient and the wear-resistant pressure-resistant performance of the composite material on the basis of ensuring the excellent corrosion resistance, electrical insulation performance, heat resistance, oil resistance, solvent resistance, moisture resistance and low temperature resistance of the fluoroplastic material, and reduces the manufacturing cost and the operating cost of the flue gas heat exchange device which takes the fluoroplastic as the material of the heat exchange element.

Description

Composite material

Technical Field

The invention belongs to the technical field of fluoroplastic composite materials, and particularly relates to a composite material which can be used in the industry of energy conservation and environmental protection.

Background

Plastics having fluorine atoms in their molecular structure are collectively referred to as fluoroplastics. The fluoroplastic is prepared from fluorine-containing monomers such as tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride and the like through homopolymerization or copolymerization. With the continuous development of polymer technology, the varieties of fluoroplastics are gradually increased, and the application range is gradually enlarged.

The fluoroplastic has many excellent properties such as excellent corrosion resistance and electrical insulation properties, high heat resistance, outstanding oil resistance, solvent resistance, good moisture resistance and low temperature resistance due to the fluorine atom contained in the molecular structure. Therefore, the fluoroplastic plays an important role in industrial departments such as national defense, electromechanical, metallurgy, energy conservation, environmental protection, petrochemical industry and the like.

In the energy-saving and environment-friendly industry, the temperature of the coal-fired flue gas is higher, and the coal-fired flue gas contains a large amount of pollutants, namely SO₂The fluorine plastic has the advantages of strong corrosion resistance, good surface non-stick property, wider temperature application range, aging resistance and the like, so that the fluorine plastic is frequently adopted as the material of the heat exchange element of the flue gas waste heat recovery heat exchange device.

The flue gas heat exchange device using fluoroplastics as the heat exchange element material has the following advantages:

1. excellent corrosion resistance, no requirement on smoke components and acid dew point temperature;

2. the heat exchange tube surface of the heat exchange device is smooth, does not deposit dust and scale and is easy to clean;

3. the heat exchange tube of the heat exchange device adopts a thin tube wall, so that the heat exchange performance is good and the volume is small;

4. the heat exchange tube of the heat exchange device has high flexible fatigue strength and is durable in use;

5. the heat exchange tube of the heat exchange device has good temperature resistance;

6. the heat exchange device has light weight and small load.

However, compared with a metal alloy heat exchange element, the fluoroplastic heat exchange element has the defects of low heat conductivity coefficient (0.2-0.25 w/mK) of the material and poor wear resistance and pressure resistance, so that the heat exchange area of the fluoroplastic heat exchange device is large, the raw material usage amount of the heat exchange element is large, the manufacturing cost is high, a large amount of smoke dust in smoke gas enables a fluoroplastic heat exchange element to be easily worn, the replacement amount of the heat exchange element is increased, and the operation cost is also high.

How to improve the heat conductivity coefficient and the wear-resisting pressure-resisting property of the fluoroplastic material and reduce the manufacturing cost and the operating cost of a flue gas heat exchange device which takes fluoroplastic as the material of the heat exchange element becomes a subject of the research field of fluoroplastic composite materials.

Disclosure of Invention

In view of the above technical problems, the present invention aims to provide a composite material with high thermal conductivity and high wear and pressure resistance.

In order to achieve the purpose, the invention provides the following technical scheme:

a composite material is prepared by cross-linking and mixing fluoroplastic and carbon black or graphene; in the composite material, the mass ratio of the fluoroplastic is as follows: 90% -98%; the mass ratio of the carbon black or the graphene is as follows: 2 to 10 percent.

The composite material is prepared into a plate shape or a tubular shape by adopting melting granulation and melting shaping.

The fluoroplastic is one of meltable Polytetrafluoroethylene (PFA), Fluorinated Ethylene Propylene (FEP) and modified Polytetrafluoroethylene (PTFE).

The thermal conductivity coefficient of the composite material is 0.35-0.45 w/mK.

The bursting pressure of the composite material at 200 ℃ is more than 4.0 MPa.

The wear-resisting property of the composite material is 75-90 Shore-D hardness.

A preparation method of a composite material comprises the following steps:

(1) uniformly mixing the fluoroplastic with the carbon black or the graphene according to the mass ratio of 90-98% of the fluoroplastic and the mass ratio of 2-10% of the carbon black or the graphene;

(2) adding the mixture into a fluoroplastic granulator, heating to the melting temperature of 330-370 ℃, and preparing high-concentration mixed granules by plasticizing extrusion, wire drawing, cooling and granule cutting processes;

(3) adding the high-concentration mixed granules into a fluoroplastic extruder, heating to the melting temperature of 330-370 ℃, and preparing the plate-shaped or tubular composite material of the fluoroplastic and the carbon black or the fluoroplastic and the graphene through plasticizing extrusion, die fixing, cooling and shaping processes.

In the step (1), the fluoroplastic powder is white powder with fineness less than 40 meshes.

In the step (1), the carbon black or the graphene is black powder with the fineness of less than 100 meshes.

The color of the composite material is black or grey brown.

Compared with the prior art, the invention has the beneficial effects that:

the invention improves the heat conductivity coefficient and the wear-resistant pressure-resistant performance of the composite material on the basis of ensuring the excellent corrosion resistance, electrical insulation performance, heat resistance, oil resistance, solvent resistance, moisture resistance and low temperature resistance of the fluoroplastic material, and reduces the manufacturing cost and the operating cost of the flue gas heat exchange device which takes the fluoroplastic as the material of the heat exchange element.

Drawings

FIG. 1 is a photomicrograph of a composite material of the present invention;

FIG. 2 is a photograph of a fluoroplastic powder;

FIG. 3 is a photograph of a carbon black powder;

FIG. 4 is a photograph showing the appearance of a heat exchange tube made of meltable polytetrafluoroethylene PFA;

fig. 5 is a photograph of the appearance of the tubular composite material of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The composite material is prepared by cross-linking and mixing fluoroplastic and carbon black or graphene. As shown in fig. 1, is a photomicrograph of the composite material of the present invention.

In the composite material, the mass ratio of the fluoroplastic is as follows: 90% -98%; the mass ratio of the carbon black or the graphene is as follows: 2 to 10 percent.

The fluoroplastic is meltable Polytetrafluoroethylene (PFA), or Fluorinated Ethylene Propylene (FEP), or modified Polytetrafluoroethylene (PTFE).

The preparation method of the composite material comprises the following steps:

(1) uniformly mixing white powdery fluoroplastic powder (shown in figure 2) with fineness less than 40 meshes and black powdery carbon black (shown in figure 3) or graphene powder with fineness less than 100 meshes according to the mass ratio of 90-98% of fluoroplastic and the mass ratio of 2-10% of carbon black or graphene;

The color of the composite material is black or grey brown.

Examples

A composite material is prepared from fluoroplastic and carbon black through cross-linking and mixing. The fluoroplastic is meltable polytetrafluoroethylene PFA and is white and transparent in color.

The mass ratio of the meltable polytetrafluoroethylene PFA is as follows: 94 percent, and the mass ratio of the carbon black is as follows: 6 percent, after uniformly mixing the meltable polytetrafluoroethylene PFA powder and the carbon black powder, adding the mixture into a fluoroplastic granulator, heating the mixture to the melting temperature of 340 ℃, and preparing high-concentration mixed granules; and adding the mixed granules into a fluoroplastic extruder, heating to the melting temperature of 360 ℃ to prepare the meltable polytetrafluoroethylene PFA and carbon black tubular composite material. The composite material is black in color, as shown in fig. 5.

As shown in table 1, compared with the heat exchange tube made of soluble polytetrafluoroethylene (as shown in fig. 4), the tubular composite material in the present embodiment has the advantages of improved thermal conductivity coefficient by 100%, improved burst pressure (200 ℃) by 11%, and improved hardness by 17%.

Table 1: comparison of thermal conductivity, burst pressure and hardness of heat exchange tubes made of composite materials and meltable polytetrafluoroethylene in examples

Claims

1. A composite material characterized by: the fluorine plastic is formed by cross-linking and mixing fluorine plastic and carbon black or graphene; in the composite material, the mass ratio of the fluoroplastic is as follows: 90% -98%; the mass ratio of the carbon black or the graphene is as follows: 2 to 10 percent.

2. The composite material of claim 1, wherein: the composite material is prepared into a plate shape or a tubular shape by adopting melting granulation and melting shaping.

3. The composite material of claim 1, wherein: the fluoroplastic is one of meltable Polytetrafluoroethylene (PFA), Fluorinated Ethylene Propylene (FEP) and modified Polytetrafluoroethylene (PTFE).

4. The composite material of claim 1, wherein: the thermal conductivity coefficient of the composite material is 0.35-0.45 w/mK.

5. The composite material of claim 1, wherein: the bursting pressure of the composite material at 200 ℃ is more than 4.0 MPa.

6. The composite material of claim 1, wherein: the wear-resisting property of the composite material is 75-90 Shore-D hardness.

7. A method of preparing a composite material according to any one of claims 1 to 6, characterized in that: the method comprises the following steps:

8. The method for preparing a composite material according to claim 7, characterized in that: in the step (1), the fluoroplastic powder is white powder with fineness less than 40 meshes.

9. The method for preparing a composite material according to claim 7, characterized in that: in the step (1), the carbon black or the graphene is black powder with the fineness of less than 100 meshes.

10. The method for preparing a composite material according to claim 7, characterized in that: the color of the composite material is black or grey brown.