CN118879009A - A highly wear-resistant and creep-resistant PTFE composite material and its preparation method and application - Google Patents

Abstract

The invention discloses a highly wear-resistant and creep-resistant PTFE composite material and its preparation method and application. By mass, the PTFE composite material includes 1-4 parts of reinforcing material, 1-4 parts of creep-resistant material and 100 parts of polytetrafluoroethylene; the raw material of the reinforcing material includes 1 part of talcum powder, 1 part of polytetrafluoroethylene and 0.006-0.04 parts of titanate coupling agent; the raw material of the creep-resistant material includes 1 part of alumina fiber, 1 part of polytetrafluoroethylene and 0.003-0.02 parts of silane coupling agent. Talc is strongly connected to PTFE to obtain reinforcing material, and alumina fiber is strongly connected to PTFE to obtain creep-resistant material. After reinforcing material, creep-resistant material and PTFE are mixed for the second time, fusion or molecular chain entanglement will occur between any two of the three, thereby forming a connection network between the three, so that the PTFE composite material has excellent wear resistance and creep resistance at the same time.

Description

A highly wear-resistant and creep-resistant PTFE composite material and its preparation method and application

Technical Field

The invention belongs to the technical field of polymer materials, and in particular relates to a highly wear-resistant and creep-resistant PTFE composite material and a preparation method and application thereof.

Background Art

Polytetrafluoroethylene (PTFE) is a polymer material with high temperature resistance, corrosion resistance, self-lubrication and other properties. It is widely used in sealing, anti-corrosion and other fields. However, its poor creep resistance, that is, short service life, limits its application in the diaphragm pump industry.

In addition, PTFE is a material with low surface energy, which makes PTFE have very poor affinity with other materials (such as reinforcing agents). Under the action of external forces, PTFE and the reinforcing agent will separate; therefore, the reinforcing agent will not only fail to improve the creep properties and wear resistance of the composite material, but will also greatly shorten the service life of the composite material.

In order to improve the interfacial bonding performance between PTFE and reinforcing agents, there is a scheme in the prior art to modify PTFE using nanoparticles (such as nano-silicon dioxide, nano-zirconium dioxide, etc.) and coupling agents. This is because the nanoparticles have high particle strength, surface area and surface energy. When they are mixed with a polymer matrix, there is a large contact surface between the two. At the same time, the coupling agent can ensure that the nanoparticles have a high dispersion in the polymer material and will not agglomerate. This makes the modified PTFE have stronger wear resistance.

However, this modification scheme focuses on the wear resistance of PTFE composite materials, and pays less attention to the modification of the creep resistance of PTFE.

Summary of the invention

The purpose of the present invention is to provide a highly wear-resistant and creep-resistant PTFE composite material and a preparation method and application thereof, so as to solve the problems existing in the prior art.

In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

A highly wear-resistant and creep-resistant PTFE composite material, which comprises, by weight: 1-4 parts of a reinforcing material, 1-4 parts of an anti-creep material and 100 parts of polytetrafluoroethylene;

The raw materials of the reinforcing material include: 1 part of talc, 1 part of polytetrafluoroethylene and 0.006-0.04 part of titanate coupling agent;

The raw materials of the anti-creep material include: 1 part of aluminum oxide fiber, 1 part of polytetrafluoroethylene and 0.003-0.02 parts of silane coupling agent.

The present invention also provides a method for preparing the PTFE composite material, which comprises the following steps:

S1. Modifying talc powder with a titanate coupling agent according to a preset mass ratio to obtain modified talc powder, and mixing the modified talc powder with polytetrafluoroethylene in a mass ratio of talc powder to polytetrafluoroethylene of 1:1 to obtain a reinforcing material;

S2: mixing alumina fiber, silane coupling agent and polytetrafluoroethylene according to preset weight proportions, stirring at 60-80°C for 1-3 h to obtain a creep resistant material;

S3: The reinforcing material, the anti-creep material and the polytetrafluoroethylene powder are mixed uniformly according to the preset weight proportions and dried to obtain the highly wear-resistant and anti-creep PTFE composite material.

The PTFE composite material of the present invention is added with reinforcing material and anti-creep material at the same time, wherein the reinforcing material is mixed with PTFE after talcum powder is modified by titanate coupling agent, one end of the titanate coupling agent is chemically connected with talcum powder, and the other end is mutually entangled with PTFE long chain, so as to realize the strong connection between talcum powder and PTFE; and the anti-creep material adopts alumina fiber, and under the action of silane coupling agent, alumina fiber is also coupled with PTFE to give the composite material excellent anti-creep performance. Moreover, after reinforcing material, anti-creep material and PTFE are mixed for the second time, fusion or molecular chain entanglement will occur between any two of the three, so as to form a connection network between the three, effectively improving the interface bonding performance between PTFE and talcum powder and alumina fiber, so that the PTFE composite material has excellent wear resistance and anti-creep performance at the same time.

In the present invention, modified talcum powder and modified alumina fiber are firstly mixed with PTFE in equal proportions to form reinforcing material and anti-creep material, and then mixed with PTFE for a second time. Compared with directly mixing modified talcum powder or modified alumina fiber with a large amount of PTFE, in this way, on the one hand, both the reinforcing material and the anti-creep material contain PTFE components, which are easier to melt and sinter with PTFE; on the other hand, the alumina fiber in the anti-creep material can also be entangled with the PTFE molecular chain in the reinforcing material, so that the anti-creep material and the reinforcing material can also be firmly connected; this means that the addition of alumina fiber not only gives the PTFE composite material excellent anti-creep performance, but also can synergize with the reinforcing material to further improve the wear resistance of PTFE.

Preferably, the above-mentioned high wear-resistant and creep-resistant PTFE composite material comprises, by weight: 2-3 parts of reinforcing material, 2-3 parts of creep-resistant material and 100 parts of polytetrafluoroethylene.

Preferably, in the above-mentioned highly wear-resistant and creep-resistant PTFE composite material, the titanate coupling agent is a monoalkoxy pyrophosphate type titanate coupling agent, which is more suitable for the following boiling granulation process.

Preferably, in the above-mentioned high wear-resistant and creep-resistant PTFE composite material, the silane coupling agent is silane coupling agent KH550.

Preferably, in the above-mentioned method for preparing the highly wear-resistant and creep-resistant PTFE composite material, in step S1, the modified talc powder is prepared by the following method:

(1) calcining talc at 1000-1200° C. for 3-5 min to obtain calcined talc;

(2) Using a boiling granulation process to deposit a titanate coupling agent on the surface of calcined talc to obtain a preliminary modified talc;

(3) The preliminary modified talc powder is calcined at 800-900°C for 10-15 min, and then nano-crushed to obtain the modified talc powder.

The calcination in step (1) is to remove impurities and surface oxides in the talc powder. The boiling granulation process is used in step (2) to deposit the vaporized coupling agent on the surface of the talc powder particles, which is conducive to ensuring that the coupling agent is evenly connected to the surface of the talc powder. The calcination again in step (3) is to remove the coupling agent and other impurity components that are not chemically connected to the talc powder. Nano-crushing after calcination helps to ensure that the modified talc powder can be more evenly dispersed in the PTFE.

The present invention also provides application of the above-mentioned highly wear-resistant and creep-resistant PTFE composite material in preparing a leather cup.

Preferably, the above application comprises the following steps:

(a) placing the highly wear-resistant and creep-resistant PTFE composite material into a mold and cold pressing it to obtain a pressed green body;

As a further preferred embodiment, the pressure is increased to 30-40 MPa at a rate of 3-5 MPa/min, and cold pressed at 30-40 MPa for 5-10 min;

(b) sintering the compact to obtain a leather cup;

As a further preference, the pressed blank is placed in a box-type resistance furnace, the temperature of the box-type resistance furnace is first increased to 320-350°C at a rate of 50-70°C/min and kept warm for 1-1.5 h, then increased to 380-400°C at a rate of 30-50°C/min and kept warm for 1-1.5 h, then decreased to 320-350°C at a rate of 30-50°C/min and kept warm for 1-1.5 h, finally the box-type resistance furnace is closed, and the leather cup can be taken out after cooling to room temperature.

The present invention also provides a leather cup for an air compressor, which is made of the above-mentioned high wear-resistant and creep-resistant PTFE composite material. The leather cup of the present invention has a friction coefficient of less than 0.1, a wear rate of less than 1.5%, a creep rate of less than 2%, a hardness of more than 75, a tensile strength of more than 25 MPa, and an elongation at break of more than 350%. It has excellent performance and greatly extends its service life, which is twice that of an ordinary leather cup.

DETAILED DESCRIPTION

Specific implementation modes are listed below to further describe the technical solution of the present invention in detail.

Example 1

The present embodiment provides a highly wear-resistant and creep-resistant PTFE composite material, which is composed of 2 parts of reinforcing material, 3 parts of creep-resistant material and 100 parts of polytetrafluoroethylene; wherein the raw materials of the reinforcing material are: 1 part of talcum powder, 1 part of polytetrafluoroethylene and 0.01 part of titanate coupling agent (isopropyl tri(dioctyl pyrophosphate) titanate); the raw materials of the creep-resistant material include: 1 part of alumina fiber, 1 part of polytetrafluoroethylene and 0.02 part of silane coupling agent KH550.

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

S1 prepares reinforcement material;

Specifically, it includes:

(1) calcining talc at 1000°C for 5 min to obtain calcined talc;

(2) using a boiling granulation process to deposit isopropyl tri(dioctyl pyrophosphate acyloxy) titanate on the surface of calcined talc to obtain a preliminary modified talc;

In the fluidized bed granulator, isopropyl tri(dioctyl pyrophosphate acyloxy) titanate is added during the bonding stage and is deposited on the surface of the calcined talc powder after being vaporized in the high-temperature carrier gas.

(3) calcining the preliminarily modified talc at 900°C for 10 min, and then crushing it with a nano-crusher to sieve out nano-scale modified talc powder;

(4) According to the preset reinforcing material raw material composition, the modified talcum powder and the polytetrafluoroethylene powder (pre-dried) are mixed evenly, added into anhydrous ethanol and stirred for 10 h, and then filtered and dried to obtain the reinforcing material;

S2 Preparation of creep-resistant materials;

Specifically, alumina fiber, silane coupling agent KH550 and polytetrafluoroethylene powder were mixed according to preset weight parts, and stirred at 60° C. for 3 h to obtain an anti-creep material;

S3: The reinforcing material, the anti-creep material and the polytetrafluoroethylene powder are mixed uniformly according to the preset weight proportions and dried at 100° C. for 1 h to obtain the highly wear-resistant and anti-creep PTFE composite material of this embodiment.

Example 2

The present embodiment provides a highly wear-resistant and creep-resistant PTFE composite material, which is composed of 3 parts of reinforcing material, 2 parts of creep-resistant material and 100 parts of polytetrafluoroethylene; wherein the raw materials of the reinforcing material are: 1 part of talcum powder, 1 part of polytetrafluoroethylene and 0.01 part of titanate coupling agent (isopropyl tri(dioctyl pyrophosphate) titanate); the raw materials of the creep-resistant material include: 1 part of alumina fiber, 1 part of polytetrafluoroethylene and 0.02 part of silane coupling agent KH550.

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

S1 prepares reinforcement material;

Specifically, it includes:

(1) calcining talc at 1200°C for 3 min to obtain calcined talc;

(2) using a boiling granulation process to deposit isopropyl tri(dioctyl pyrophosphate acyloxy) titanate on the surface of calcined talc to obtain a preliminary modified talc;

In the fluidized bed granulator, isopropyl tri(dioctyl pyrophosphate acyloxy) titanate is added during the bonding stage and is deposited on the surface of the calcined talc powder after being vaporized in the high-temperature carrier gas.

(3) calcining the preliminarily modified talc at 800°C for 15 min, and then crushing it with a nano-crusher to sieve out nano-scale modified talc powder;

(4) According to the preset reinforcing material raw material composition, the modified talcum powder and the polytetrafluoroethylene powder (pre-dried) are mixed evenly, added into anhydrous ethanol and stirred for 10 h, and then filtered and dried to obtain the reinforcing material;

S2 Preparation of creep-resistant materials;

Specifically, alumina fiber, silane coupling agent KH550 and polytetrafluoroethylene powder were mixed according to preset weight parts, and stirred at 60° C. for 3 h to obtain an anti-creep material;

S3: The reinforcing material, the anti-creep material and the polytetrafluoroethylene powder are mixed uniformly according to the preset weight proportions and dried at 100° C. for 1 h to obtain the highly wear-resistant and anti-creep PTFE composite material of this embodiment.

Example 3

The present embodiment provides a leather cup for an air compressor, which is prepared using the PTFE composite material prepared in Example 1, and the preparation method includes:

(a) placing a highly wear-resistant and creep-resistant PTFE composite material into a mold and cold pressing it to obtain a green compact;

Specifically, the pressure was increased to 40 MPa at a rate of 5 MPa/min, and cold pressed at 40 MPa for 5 min;

(b) sintering the compact to obtain a leather cup;

Specifically, the pressed blank is placed in a box-type resistance furnace, and the temperature of the box-type resistance furnace is first increased to 320°C at a rate of 50°C/min and kept for 1 h, then increased to 380°C at a rate of 30°C/min and kept for 1.5 h, then decreased to 320°C at a rate of 30°C/min and kept for 1.5 h, and finally the box-type resistance furnace is closed, and the leather cup can be taken out after cooling to room temperature.

Example 4

The present embodiment provides a leather cup for an air compressor, which is prepared using the PTFE composite material prepared in Example 2, and the preparation method includes:

(a) placing a highly wear-resistant and creep-resistant PTFE composite material into a mold and cold pressing it to obtain a green compact;

Specifically, the pressure was increased to 30 MPa at a rate of 3 MPa/min, and cold pressed at 30 MPa for 10 min;

(b) sintering the compact to obtain a leather cup;

Specifically, the pressed blank is placed in a box-type resistance furnace, and the temperature of the box-type resistance furnace is first increased to 350°C at a rate of 70°C/min and kept for 1.5 h, then increased to 400°C at a rate of 50°C/min and kept for 1 h, then decreased to 350°C at a rate of 50°C/min and kept for 1 h, and finally the box-type resistance furnace is closed, and the leather cup can be taken out after cooling to room temperature.

Comparative Example 1

The comparative example provides a PTFE composite material, which is composed of 5 parts of reinforcing material and 100 parts of polytetrafluoroethylene, wherein the raw materials of the reinforcing material are: 1 part of talc powder, 1 part of polytetrafluoroethylene and 0.01 part of titanate coupling agent (isopropyl tri(dioctyl pyrophosphate) titanate).

The preparation method of the PTFE is substantially the same as that of Example 1, except that step S2 is not included.

Comparative Example 2

The comparative example provides a PTFE composite material, which is composed of 5 parts of anti-creep material and 100 parts of polytetrafluoroethylene, wherein the raw materials of the anti-creep material include: 1 part of aluminum oxide fiber, 1 part of polytetrafluoroethylene and 0.02 parts of silane coupling agent KH550.

The preparation method of the PTFE is substantially the same as that of Example 1, except that step S1 is not included.

Comparative Example 3

The comparative example provides a PTFE composite material, which is composed of 1 part of reinforcing material, 1.5 parts of anti-creep material and 100 parts of polytetrafluoroethylene; wherein the raw materials of the reinforcing material are: 1 part of talcum powder and 0.01 part of titanate coupling agent (isopropyl tri(dioctyl pyrophosphate acyloxy) titanate); the raw materials of the anti-creep material are: 1 part of alumina fiber and 0.02 part of silane coupling agent KH550.

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

S1 prepares reinforcement material;

Specifically, it includes:

(1) calcining talc at 1000°C for 5 min to obtain calcined talc;

(2) using a boiling granulation process to deposit isopropyl tri(dioctyl pyrophosphate acyloxy) titanate on the surface of calcined talc to obtain a preliminary modified talc;

In the fluidized bed granulator, isopropyl tri(dioctyl pyrophosphate acyloxy) titanate is added during the bonding stage and is deposited on the surface of the calcined talc powder after being vaporized in the high-temperature carrier gas.

(3) calcining the preliminarily modified talc at 900°C for 10 min, and then crushing it with a nano-crusher to sieve out nano-scale modified talc powder to obtain the reinforcing material;

S2: The reinforcing material, the anti-creep material and the polytetrafluoroethylene powder are mixed uniformly according to the preset weight proportions, and stirred at 60° C. for 3 h to obtain the highly wear-resistant and anti-creep PTFE composite material of this embodiment.

Comparative Examples 4-6

The present comparative example is a leather cup for an air compressor, which is prepared using the PTFE composite materials of comparative examples 1-3 respectively, and the preparation process is the same as that of example 3.

Various properties of the leather cups prepared in Examples 3-4 and Comparative Examples 4-6 were tested, and the test results are shown in Table 1.

Table 1

As can be seen from Table 1, the leather cup prepared by using the PTFE composite material of the present invention has both excellent wear resistance and creep resistance. The addition of the creep resistance material not only gives the PTFE material excellent creep resistance, but also helps to further improve the wear resistance of the PTFE composite material. From the test results of Examples 3-4 and Comparative Example 6, it can be seen that PTFE is first mixed with talcum powder and alumina fiber in equal proportions, coupled, and then mixed with PTFE powder for a second time, which helps to ensure that PTFE maintains good interface bonding ability with talcum powder and alumina fiber.

Claims (10)

1. The high wear-resistant creep-resistant PTFE composite material is characterized by comprising the following components in parts by mass: 1-4 parts of reinforcing material, 1-4 parts of creep resistant material and 100 parts of polytetrafluoroethylene;

Wherein, the raw materials of the reinforcing material comprise: 1 part of talcum powder, 1 part of polytetrafluoroethylene and 0.006-0.04 part of titanate coupling agent;

The creep-resistant material comprises the following raw materials: 1 part of alumina fiber, 1 part of polytetrafluoroethylene and 0.003 to 0.02 part of silane coupling agent.

2. The high wear resistant creep resistant PTFE composite of claim 1 wherein the titanate coupling agent is a monoalkoxy pyrophosphate type titanate coupling agent.

3. The high wear resistant creep resistant PTFE composite of claim 1 wherein said silane coupling agent is silane coupling agent kh550.

4. A method of preparing a highly wear-resistant creep-resistant PTFE composite according to any one of claims 1 to 3, comprising the steps of:

S1, modifying talcum powder by using titanate coupling agent according to preset mass parts to obtain modified talcum powder, and uniformly mixing the modified talcum powder and polytetrafluoroethylene according to the mass ratio of talcum powder to polytetrafluoroethylene of 1:1 to obtain a reinforcing material;

S2, uniformly mixing alumina fiber, a silane coupling agent and polytetrafluoroethylene according to preset mass parts, and stirring at 60-80 ℃ for 1-3 h to obtain a creep resistant material;

And S3, uniformly mixing the reinforcing material, the creep-resistant material and the polytetrafluoroethylene powder according to the preset mass parts, and drying to obtain the high wear-resistant and creep-resistant PTFE composite material.

5. The method of claim 4, wherein in step S1, the modified talc is prepared by:

(1) Calcining talcum powder at 1000-1200 deg.c for 3-5 min to obtain calcined talcum powder;

(2) Depositing titanate coupling agent on the surface of calcined talcum powder by adopting a boiling granulation process to obtain primary modified talcum powder;

(3) The preliminary modified talcum powder is placed at 800-900 ℃ for calcination for 10-15 min, and then the modified talcum powder is obtained after nano-crushing.

6. Use of a highly wear-resistant creep-resistant PTFE composite according to any of claims 1-3 for the preparation of a cup.

7. The use according to claim 6, comprising the steps of:

(a) Placing the high wear-resistant creep-resistant PTFE composite material into a mould for cold press molding to obtain a pressed compact;

(b) And sintering and molding the pressed compact to obtain the leather cup.

8. The use according to claim 6, wherein in step (a) the pressure is raised to 30-40 MPa at a rate of 3-5 MPa/min and cold-pressed at 30-40 MPa for 5-10 min.

9. The use according to claim 6, wherein in step (b), the green compact is placed in a box-type resistance furnace, the temperature of the box-type resistance furnace is raised to 320-350 ℃ at a rate of 50-70 ℃/min and kept at 1-1.5 h, then raised to 380-400 ℃ at a rate of 30-50 ℃/min and kept at 1-1.5 h, then lowered to 320-350 ℃ at a rate of 30-50 ℃/min and kept at 1-1.5 h, finally the box-type resistance furnace is closed and cooled to room temperature.

10. A cup for an air compressor, which is made of the high wear-resistant and creep-resistant PTFE composite material according to any one of claims 1 to 3.