阅读说明：本技术 一种高透气聚四氟乙烯薄膜及其制备方法和模具 (High-breathability polytetrafluoroethylene film and preparation method and mold thereof ) 是由 余佳彬 郭晓蓓 费传军 高政 李帅 张振 尹奕玲 徐涛 匡新波 周诚 魏涛 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种高透气聚四氟乙烯薄膜及其制备方法和模具,所述高透气聚四氟乙烯薄膜的制备模具的挤出口模的出口为扁口,所述口模段内设置有n个间隔板,所述n个间隔板将所述口模内的至少一部分分隔为n+1个隔开的挤出段,所述n≥1。本发明高透气聚四氟乙烯薄膜的制备方法为：将坯体通过上述的制备模具的挤出口模挤出后制得聚四氟乙烯薄膜。本发明的坯体采用有间隔板的模具挤出,能够增大PTFE与模具间的剪切,可以有效提升挤出段PTFE的纤维化程度,可以在不改变薄膜厚度,保持力学性能的情况下,充分提升薄膜的透气性和均匀性。(The invention discloses a high-permeability polytetrafluoroethylene film and a preparation method and a mold thereof, wherein an outlet of an extrusion die of the high-permeability polytetrafluoroethylene film preparation mold is a flat port, n partition plates are arranged in a die section, at least one part in the die is divided into n +1 separated extrusion sections by the n partition plates, and n is more than or equal to 1. The preparation method of the high-permeability polytetrafluoroethylene film comprises the following steps: and extruding the blank through the extrusion die of the preparation die to obtain the polytetrafluoroethylene film. The blank body is extruded by the die with the partition plate, so that the shearing between PTFE and the die can be increased, the fiberization degree of PTFE at an extrusion section can be effectively improved, and the air permeability and the uniformity of the film can be fully improved under the conditions of not changing the thickness of the film and keeping the mechanical property.)

1. The preparation mold of the high-permeability polytetrafluoroethylene film is characterized in that an outlet of an extrusion die of the mold is a flat opening, n partition plates are arranged in a die section, at least one part in the die is divided into n +1 separated extrusion sections by the n partition plates, and n is larger than or equal to 1.

2. The mold for preparing a polytetrafluoroethylene film with high breathability according to claim 1, wherein the outlet of the extrusion die of the mold is rectangular.

3. The mold for preparing a polytetrafluoroethylene film with high breathability according to claim 1 or 2, wherein the n partition plates are arranged in parallel, and the distance between two adjacent partition plates is the same or different.

4. The mold for preparing a polytetrafluoroethylene film with high breathability according to claim 2, wherein the rectangle has a length L and a width H, and the n spacers are arranged along the length direction.

5. The mold for preparing the high-permeability polytetrafluoroethylene film according to claim 4, wherein the length L is 100mm, the width H is 20mm, and n is 1; or the length L is 150mm, the width H is 30mm, and n is 2; or the length L is 180mm, the width H is 36mm, and n is 3.

6. A process for preparing a highly breathable polytetrafluoroethylene film, characterized in that a polytetrafluoroethylene film is obtained by extruding a green body through an extrusion die of a preparation die according to any one of claims 1 to 5.

7. The preparation method according to claim 6, wherein the preparation process of the green body is as follows: and mixing polytetrafluoroethylene resin and an oil agent, aging for a period of time, filling materials into a blank making machine, and pressing to form the blank.

8. The preparation method according to claim 7, wherein the oil agent is one of aviation kerosene, petroleum ether and isoparaffin.

9. The method according to claim 7, wherein the polytetrafluoroethylene film is produced by subjecting a multilayer sheet obtained by extruding the green body through an extrusion die of the production die to calendering to give a sheet having a predetermined thickness and stretching synchronously or asynchronously in the longitudinal and transverse directions.

10. A highly breathable polytetrafluoroethylene film, wherein said polytetrafluoroethylene film is produced by the process of any one of claims 6 to 9.

Technical Field

The invention belongs to the technical field of polymer microporous films, and particularly relates to a high-breathability polytetrafluoroethylene film, and a preparation method and a mold thereof.

Background

The microporous film is made up by using polytetrafluoroethylene as raw material through the processes of puffing and stretching, and can be covered on various fabrics and base materials by means of special process to obtain the invented filtering material, and its pore size is small, distribution is uniform, porosity is large, at the same time of retaining air circulation it can filter all dust particles including bacteria so as to attain the goal of purification and ventilation.

In the use process of the polytetrafluoroethylene microporous membrane, the air permeability is a very key index, and the improvement of the air permeability and the air permeability uniformity of the PTFE microporous membrane is a common target in the industry at present. The conventional film preparation process comprises the steps of mixing polytetrafluoroethylene resin and an oil agent, filling the mixture into a blank making machine, pressing the mixture to form a blank with consistent compactness, extruding the blank through a round opening die, rolling and stretching the blank in a longitudinal and transverse asynchronous mode to form a film, wherein the extrusion mode of the round opening die is adopted, the improvement of the fiberization degree of the film is very limited, and the ventilation and uniformity of the film are required to be improved.

Disclosure of Invention

The invention aims to provide a polytetrafluoroethylene film with air permeability and high uniformity, and a preparation method and a mold thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the preparation mold of the high-permeability polytetrafluoroethylene film is characterized in that an outlet of an extrusion die of the mold is a flat opening, n partition plates are arranged in a die section, at least one part in the die is divided into n +1 separated extrusion sections by the n partition plates, and n is larger than or equal to 1.

Further, the outlet of the extrusion die of the die is rectangular.

Further, n spacer plate parallel arrangement, the interval of two adjacent spacer plates is the same or different, and when all setting up the interval with the spacer plate the same, the film of producing is also all the same, and when the film that if needs produced was different, can set up the interval of spacer plate according to specific demand, the thickness of the film that different intervals produced, fibrosis degree and aperture also all are different to can once produce the film of different specifications on the basis of satisfying the high air permeability of film.

Furthermore, the length of the rectangle is L, the width of the rectangle is H, and the n partition plates are arranged along the length direction.

Further, the length L is 100mm, the width H is 20mm, and n is 1; or the length L is 150mm, the width H is 30mm, and n is 2; or the length L is 180mm, the width H is 36mm, and n is 3.

A preparation method of a high-permeability polytetrafluoroethylene film is characterized in that a blank is extruded through an extrusion die of the preparation die to prepare the polytetrafluoroethylene film.

Further, the preparation process of the blank body comprises the following steps: and mixing polytetrafluoroethylene resin and an oil agent, aging for a period of time, filling materials into a blank making machine, and pressing to form the blank.

Further, the oil agent is one of aviation kerosene, petroleum ether and isoparaffin.

And further, extruding the blank through an extrusion die of the preparation die to obtain a multilayer sheet, calendaring the multilayer sheet to form a sheet with a certain thickness, and stretching the sheet in a longitudinal and transverse synchronous or asynchronous mode to prepare the polytetrafluoroethylene film.

The high-permeability polytetrafluoroethylene film is prepared by the method.

Compared with the prior art, the invention has the remarkable advantages that:

(1) the blank body is extruded by the die with the partition plate, so that the shearing between PTFE and the die can be increased, the fiberization degree of PTFE at an extrusion section can be effectively improved, and the air permeability and the uniformity of the film can be fully improved under the conditions of not changing the thickness of the film and keeping the mechanical property;

(2) in the die, the width (L) and the height (H) of the die outlet and the number of the partition plates can be specifically designed and selected according to different products, and the width and the height of the die and the number of the partition plates are reasonably designed according to the requirement of the air permeability of the film, so that the fiberization degree is highest and the performance is optimal under the performances of different types of films;

(3) the distance between two adjacent partition plates is the same or different, when the distances between the partition plates are the same, the produced films are also the same, if the films required to be produced are different, the distances between the partition plates can be set according to specific requirements, and the thickness, the fiberization degree and the pore diameter of the films produced at different distances are different, so that the films with different specifications can be produced at one time on the basis of meeting the high air permeability of the films.

Drawings

FIG. 1 is a top view of a mold for preparing a highly breathable polytetrafluoroethylene film of the invention.

FIG. 2 is a front view of the outlet of the mold for preparing the highly breathable polytetrafluoroethylene film of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The following describes the implementation of the present invention in detail with reference to specific embodiments.

Referring to the drawings 1-2, the high-permeability polytetrafluoroethylene film preparation mold is characterized in that an outlet of an extrusion die of the mold is a flat opening, n partition plates are arranged in a die section, at least one part in the die is divided into n +1 separated extrusion sections by the n partition plates, and n is larger than or equal to 1.

Preferably, in connection with fig. 2, the exit of the extrusion die of the die is rectangular in shape.

Preferably, the n spacing plates are arranged in parallel, and the spacing between two adjacent spacing plates is the same or different.

Preferably, the length of the rectangle is L, the width of the rectangle is H, that is, the width of the die outlet is L, and the height of the die outlet is H, the n partition plates are arranged along the length direction of the rectangle, and fig. 2 is a front view of the outlet (the lower end part in fig. 1) in fig. 1.

A process for preparing the high-air-permeability teflon film includes such steps as mixing teflon resin with oil, ageing in ageing box at low temp for a certain time, filling material in blank-making machine, pressing by blank-making machine to obtain cylindrical blank, extruding out the blank through the extruding die to obtain multi-layer sheet, extruding out to obtain the multi-layer sheet, shearing (kneading and extruding) between sheet layer and die, calendering to obtain a sheet with a certain thickness, and longitudinal and transverse synchronous or asynchronous stretching.

Preferably, the oil agent is one of aviation kerosene, petroleum ether and isoparaffin.

On the membrane filter material, the aim of high efficiency and low resistance is always pursued, the PTFE membrane plays a key role, and the conventional understanding shows that the membrane is thin, the air permeability is increased, the resistance is low, but the efficiency is also reduced, and the mechanical property is also reduced; the invention increases the degree of fibrosis from the extrusion section of film forming, so that in the film node-fiber structure, the proportion of nodes is reduced, the density of fibers is increased, more micropores are formed, and the air permeability and uniformity are improved.

The air permeability and uniformity of the microporous membrane are improved, and the microporous membrane is closely related to the fiberization degree and the fiberization distribution state of the PTFE paste in the die head extrusion process link. The higher the degree of fiberization of the PTFE paste after extrusion molding and the more uniform the fiberization distribution, the higher the air permeability and the more uniform the air permeability of the finished film after the stretching process. The fiberization is a phenomenon in which fine particles in the PTFE dispersion resin particles are regularly arranged in a predetermined direction under the action of shear force to form a fibrous shape.

The following examples and comparative examples illustrate the practice and effects of the present invention.