CN110962376B - Novel expanded polytetrafluoroethylene composite membrane and preparation method thereof - Google Patents

Novel expanded polytetrafluoroethylene composite membrane and preparation method thereof Download PDF

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Publication number
CN110962376B
CN110962376B CN201811140422.3A CN201811140422A CN110962376B CN 110962376 B CN110962376 B CN 110962376B CN 201811140422 A CN201811140422 A CN 201811140422A CN 110962376 B CN110962376 B CN 110962376B
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film
roller
expanded polytetrafluoroethylene
cooling
composite membrane
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CN110962376A (en
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赵凡
杨帆
钟子强
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Zhonghao Chenguang Research Institute of Chemical Industry Co Ltd
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Zhonghao Chenguang Research Institute of Chemical Industry Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
    • B29C71/02—Thermal after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
    • B29C71/02—Thermal after-treatment
    • B29C2071/025—Quenching, i.e. rapid cooling of an object

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Laminated Bodies (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

The invention relates to a novel expanded polytetrafluoroethylene composite membrane and a preparation method thereof. The preparation method comprises the following steps: after the heat treatment, the roller is cooled to 260-300 ℃, and then is chilled to normal temperature. The invention can control the density of the expanded polytetrafluoroethylene composite membrane to a certain extent by improving the cooling mode, and greatly shortens the production process time.

Description

Novel expanded polytetrafluoroethylene composite membrane and preparation method thereof
Technical Field
The invention belongs to the technical field of plastic processing, and particularly relates to a preparation method of a novel expanded polytetrafluoroethylene composite membrane.
Background
The polytetrafluoroethylene material has the advantages of corrosion resistance, weather resistance, high and low temperature resistance and the like, is widely applied to important departments such as national defense and military industry, atomic energy, petroleum, radio, electric power machinery, chemical industry and the like, and is called as plastic king. Compared with the traditional polytetrafluoroethylene material formed by die pressing or basic forming, the expanded polytetrafluoroethylene has lower density and stronger creep resistance, simultaneously retains the physical and chemical properties of a plurality of traditional PTFE, and is an ideal sealing material.
The single-layer expanded polytetrafluoroethylene film is widely used in the chemical filtration industry and the special clothing production industry; the multilayer composite film can be made into various sealing materials and widely applied to special military industries such as aerospace, navigation and the like.
The traditional preparation method of the expanded polytetrafluoroethylene composite membrane is to naturally roll a single-layer expanded polytetrafluoroethylene membrane onto a base material (a roller or a steel belt, etc.), and naturally cool the membrane after heat treatment. The density of the composite membrane obtained by the method is uncontrollable, the time consumption is long, and the production efficiency is low.
Disclosure of Invention
The invention aims to provide a novel preparation method of an expanded polytetrafluoroethylene composite membrane, which can control the density of the expanded polytetrafluoroethylene composite membrane to a certain extent and greatly shorten the production process time by improving the cooling mode.
The technical scheme of the scheme is as follows.
A method for preparing a novel expanded polytetrafluoroethylene composite membrane comprises the following steps: after the heat treatment, the roller is cooled to 260-300 ℃, and then is chilled to normal temperature.
Further, the chilling speed is 15-30 ℃/min.
In the invention, the chilling can adopt various modes, such as air cooling, water cooling or other medium cooling which does not pollute products; in the invention, the adopted roller is placed in a cooling water pool for chilling.
By adopting the cooling treatment method, the density of the obtained composite membrane is controlled to be 0.5-0.7g/cm3Meanwhile, the cooling time is controlled within 60min, preferably within 30min, so that the production time is greatly shortened, and the production benefit is improved.
Further, the preparation method of the novel expanded polytetrafluoroethylene composite membrane comprises the following steps: and (2) overlapping the multilayer biaxially oriented polytetrafluoroethylene film on the surface of the roller under a certain pressure, cooling to 260-300 ℃ after heat treatment, and then chilling to normal temperature.
The method comprises the following specific steps:
(1) preparing a base film: preparing a calendered film from the dispersed polytetrafluoroethylene resin by a paste forming method, and performing biaxial tension to prepare an expanded polytetrafluoroethylene film;
(2) film covering: the obtained expanded polytetrafluoroethylene film is rolled up to a film coating roller at a certain speed and pressure by a film coating unit; after the required thickness is reached, fixing the films at two ends of the film laminating roller, and then detaching the roller;
(3) and (3) sintering: carrying out heat treatment on the film-coated roller at the temperature of 350-400 ℃ for 1-3 hours;
(4) and (3) cooling: after heat treatment, the roller is moved out, when the temperature of the inner wall of the roller is reduced to 260-300 ℃, the roller is put into a water tank for chilling, the temperature is reduced to normal temperature at a cooling speed of 15-30 ℃/min, and the roller is moved out;
(5) cutting and packaging: and taking the cooled film off the roller, and cutting and packaging according to requirements.
In the step (1), the thickness of the expanded polytetrafluoroethylene film can be 0.03-0.1 mm; preferably within a thickness tolerance of + -0.02 mm.
In the step (2), the film covering machine set comprises: a flattening roller, a circular film-coated roller (detachable), a pressure device and the like; the pressure device presses the rubber roller on the film covering roller in a pneumatic or hydraulic adjusting mode. The film laminating roller is made of stainless steel, and the length and the diameter of the film laminating roller are determined according to the size of a film laminating machine set.
Preferably, the film rolling speed is 5 circles per minute, the pressure is 0.2-0.4MPa, and the rolling thickness is 3.0-3.4 mm. Further preferably, the pressure is 0.3 MPa.
In the step (3), the heat treatment can be carried out in an oven or a salt bath furnace; the preferred heat treatment temperature is 360-380 ℃.
In the step (4), in the chilling process, cooling is carried out by using circulating cooling water, and the roller is completely immersed in water and cooled to normal temperature; preferably, the temperature of the inner wall of the roller is reduced to 260-300 ℃, then the roller is placed into a water tank, and the roller is removed after being cooled to the normal temperature.
The invention also provides the expanded polytetrafluoroethylene composite membrane prepared by the method, and the density of the composite membrane is uniform and is controlled to be 0.5-0.7g/cm3The thickness is 2.2-2.6 mm, and the surface is flat and free of bulges.
The invention has the following beneficial effects:
the invention adopts a chilling cooling mode, and can effectively control the density of the composite film to be 0.5-0.7g/cm by controlling the chilling speed3Within the range, thickness is at 2.1 ~ 2.7mm, and the cooling in-process does not have the swell, and gained complex film surfacing, and practices thrift the certain time, promotes production efficiency.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Example 1
The embodiment provides a preparation method of an expanded polytetrafluoroethylene composite membrane, which comprises the following steps:
firstly, preparing a calendered film from the dispersed polytetrafluoroethylene resin by a paste forming method, and preparing an expanded polytetrafluoroethylene film through biaxial stretching, wherein the thickness of the film is 0.05 +/-0.02 mm.
And secondly, winding the prepared film onto a film coating roller through a film coating unit, wherein the film winding speed is 5 circles per minute, the pressure is 0.30MPa, the winding thickness is 3.0-3.4 mm, films at two ends of the film coating roller are fixed, and then the roller is dismounted.
Thirdly, the film coating roller coated with the film is subjected to heat treatment in a salt bath furnace, wherein the heat treatment temperature is 370 ℃, and the treatment time is 2 hours.
And fourthly, moving out the roller after heat treatment, when the temperature of the inner wall of the roller is reduced to 300 ℃, putting the roller into a water tank, and moving out after the temperature of the roller is cooled to normal temperature. In the process, the cooling rate is 25 ℃/min, and the use time is 11 min.
Taking the cooled film off the roller, cutting and packaging according to requirements.
The cooling process of the embodiment has no bulge, and the surface of the obtained composite film is smooth. Film density 0.7 + -0.05 g/cm3And the thickness is 2.1-2.5 mm.
Example 2
The embodiment provides a preparation method of an expanded polytetrafluoroethylene composite membrane, which comprises the following steps:
firstly, preparing a calendered film from the dispersed polytetrafluoroethylene resin by a paste forming method, and preparing an expanded polytetrafluoroethylene film through biaxial stretching, wherein the thickness of the film is 0.05 +/-0.02 mm.
And secondly, winding the prepared film onto a film coating roller through a film coating unit, wherein the film winding speed is 5 circles per minute, the pressure is 0.30MPa, the winding thickness is 3.0-3.4 mm, films at two ends of the film coating roller are fixed, and then the roller is dismounted.
Thirdly, the film coating roller coated with the film is subjected to heat treatment in a salt bath furnace, the heat treatment temperature is 370 ℃, the treatment time is 2 hours, and the film coating roller is naturally cooled at room temperature after the heat treatment.
And fourthly, moving out the roller after heat treatment, when the temperature of the inner wall of the roller is reduced to 280 ℃, putting the roller into a water tank, and moving out after the temperature of the roller is cooled to the water temperature. In the process, the cooling rate is 20 ℃/min, and the time is 13 min.
Taking the cooled film off the roller, cutting and packaging according to requirements.
The cooling process of the embodiment has no bulge, and the surface of the obtained composite film is smooth. Film density 0.65 + -0.05 g/cm3And the thickness is 2.2-2.6 mm.
Example 3
The embodiment provides a preparation method of an expanded polytetrafluoroethylene composite membrane, which comprises the following steps:
firstly, preparing a calendered film from the dispersed polytetrafluoroethylene resin by a paste forming method, and preparing an expanded polytetrafluoroethylene film through biaxial stretching, wherein the thickness of the film is 0.05 +/-0.02 mm.
And secondly, winding the prepared film onto a film coating roller through a film coating unit, wherein the film winding speed is 5 circles per minute, the pressure is 0.30MPa, the winding thickness is 3.0-3.4 mm, films at two ends of the film coating roller are fixed, and then the roller is dismounted.
Thirdly, the film coating roller coated with the film is subjected to heat treatment in a salt bath furnace, the heat treatment temperature is 370 ℃, the treatment time is 2 hours, and the film coating roller is naturally cooled at room temperature after the heat treatment.
And fourthly, moving out the roller after heat treatment, when the temperature of the inner wall of the roller is reduced to 260 ℃, putting the roller into a water tank, and moving out after the temperature of the roller is cooled to the water temperature. In the process, the cooling rate is 20 ℃/min, and the use time is 12 min.
Taking the cooled film off the roller, cutting and packaging according to requirements.
No bulge is generated in the temperature process of the embodiment, and the surface of the obtained composite membrane is smooth. Film density 0.55 + -0.05 g/cm3And the thickness is 2.3-2.7 mm.
Comparative example 1
This example provides a method for preparing an expanded polytetrafluoroethylene composite membrane, which is different from example 1 in that,
and fourthly, removing the roller after heat treatment, and naturally cooling to room temperature for 8 hours.
Local swell phenomenon appears in this example cooling process, and cockle when the gained complex film tiling. Film density at the position without bulge is 0.5 +/-0.05 g/cm3Film density at bulge position of 0.45 +/-0.05 g/cm3And the thickness is 2.1-3.1 mm.
Comparative example 2
This example provides a method for preparing an expanded polytetrafluoroethylene composite membrane, which is different from example 1 in that,
the cooling speed of the step IV is 35 ℃/min, the local bulging phenomenon does not occur in the cooling process of the embodiment, but the composite film shrinks greatly due to the excessively high cooling speed, so that the surface cracks occur, and the use requirement cannot be met.
Comparative example 3
This example provides a method for preparing an expanded polytetrafluoroethylene composite membrane, which is different from example 1 in that,
the cooling rate of the step (iv) is 10 ℃/min, a local bulge phenomenon occurs in the cooling process of the embodiment, compared with the comparative example 1, the bulge is slightly small, and the obtained composite film has wrinkles when being tiled. Film density at the position without bulge is 0.5 +/-0.05 g/cm3Film density at bulge position of 0.45 +/-0.05 g/cm3And the thickness is 2.1-3.0 mm.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (7)

1. A preparation method of a novel expanded polytetrafluoroethylene composite membrane is characterized by comprising the following steps:
(1) preparing a base film: preparing a calendered film from the dispersed polytetrafluoroethylene resin by a paste forming method, and performing biaxial tension to prepare an expanded polytetrafluoroethylene film;
the thickness of the expanded polytetrafluoroethylene film is 0.03-0.1 mm; the winding thickness is 3.0-3.4 mm;
(2) film covering: the obtained expanded polytetrafluoroethylene film passes through a film covering machine set and is wound onto a film covering roller at a certain speed and under a certain pressure; after the required thickness is reached, fixing the films at two ends of the film laminating roller, and detaching the roller;
the pressure is 0.2-0.4 MPa;
(3) and (3) sintering: carrying out heat treatment on the roller coated with the film at 350-400 ℃;
(4) and (3) cooling: after heat treatment, the roller is removed, naturally cooled to 260-300 ℃, and chilled at a cooling speed of 15-30 ℃/min to normal temperature;
the density of the composite membrane is 0.5-0.7g/cm3The thickness is 2.1-2.7 mm.
2. The preparation method according to claim 1, wherein the chilling mode is air cooling, water cooling or medium cooling.
3. The manufacturing method according to claim 1, wherein in the step (2), the film winding speed is 5 circles/minute during the film covering process; the pressure was 0.3 MPa.
4. The production method according to claim 1, wherein in the step (3), the heat treatment is performed in an oven or a salt bath furnace.
5. The method as claimed in claim 4, wherein the heat treatment temperature is 360-380 ℃.
6. The method according to claim 1, wherein in the step (4), the chilling process is carried out by using circulating cooling water, and the roller is completely immersed in the water.
7. An expanded polytetrafluoroethylene composite membrane made by the process of any one of claims 1 to 6.
CN201811140422.3A 2018-09-28 2018-09-28 Novel expanded polytetrafluoroethylene composite membrane and preparation method thereof Active CN110962376B (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102276950A (en) * 2011-05-18 2011-12-14 湖州松华橡塑有限公司 Polytetrafluoroethylene (PTFE) composite material sealing ring with high temperature resistance and low creep, and preparation method thereof
CN103963309A (en) * 2014-04-22 2014-08-06 湖州森诺氟材料科技有限公司 High-strength transparent polytetrafluoroethylene building membrane and preparation method thereof
CN106863860A (en) * 2017-01-12 2017-06-20 浙江国泰萧星密封材料股份有限公司 A kind of preparation method of high intensity EPTFE bands

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102276950A (en) * 2011-05-18 2011-12-14 湖州松华橡塑有限公司 Polytetrafluoroethylene (PTFE) composite material sealing ring with high temperature resistance and low creep, and preparation method thereof
CN103963309A (en) * 2014-04-22 2014-08-06 湖州森诺氟材料科技有限公司 High-strength transparent polytetrafluoroethylene building membrane and preparation method thereof
CN106863860A (en) * 2017-01-12 2017-06-20 浙江国泰萧星密封材料股份有限公司 A kind of preparation method of high intensity EPTFE bands

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