Preparation method and preparation device of polytetrafluoroethylene building membrane material

Abstract

The invention discloses a preparation method and a preparation device of a polytetrafluoroethylene building membrane material. The preparation method comprises the following steps: firstly, carrying out surface treatment on glass fiber cloth; and immersing the treated glass fiber cloth into the polytetrafluoroethylene emulsion to form a pre-cured layer. And immersing the glass fiber cloth into a mixed solution of color paste and polytetrafluoroethylene, and coloring. And finally, covering the surface of the glass fiber cloth coating. According to the preparation method and the preparation device of the polytetrafluoroethylene building membrane material, membrane materials with different colors can be prepared, the membrane materials have good tensile strength and tearing strength, and the surface of the membrane materials has good self-cleaning performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building membrane, in particular to a preparation method and device of polytetrafluoroethylene building membrane. BACKGROUND

[0002] Membrane structure is a new type of large-span space structure developed in recent decades. With the emergence of building membrane made of glass fiber fabric coated with polytetrafluoroethylene, membrane structure has made rapid progress in recent decades, and building membrane has been widely used in various large-scale construction projects, such as large sports stadiums, commercial public facilities, amusement parks, exhibition halls, airport halls, train stations and various large facilities. Currently, the color of widely used building membrane is generally white, but with the diversification of design created by membrane structure designers, the demand for other colors is also increasing.

[0003] Currently, dyeing on glass fiber membrane usually adopts the way of dipping dye, adding color paste in the coating and coating on the glass fiber cloth. Since the polytetrafluoroethylene coating will go through high temperature in the coating process, the components in the color paste will have oxidation reaction with the glass fiber under high temperature, which will affect the physical strength of the glass fiber; and the membrane is generally used outdoors, and impurities are easy to deposit on the surface, affecting the appearance. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a preparation method and device of polytetrafluoroethylene building membrane, which can prepare membrane with different colors, good tensile strength and tear strength, and good self-cleaning performance on the surface.

[0005] The technical solution adopted by the present application to solve the technical problem is: a preparation method of polytetrafluoroethylene building membrane, the preparation method comprising the following steps:

[0006] 1) Pretreatment: high temperature treatment is performed on the glass fiber base cloth to remove the surface treatment agent;

[0007] 2) Infiltration treatment: the pretreated glass fiber base cloth is immersed in an infiltration agent containing silane coupling agent and dimethyl silicone oil, and after infiltration, drying treatment is performed;

[0008] 3) Pre-curing treatment: the glass fiber base cloth after infiltration treatment is immersed in polytetrafluoroethylene emulsion, and gradient temperature drying is performed to form a pre-cured layer;

[0009] 4) Dyeing treatment: the glass fiber base cloth after pre-curing treatment is immersed in polytetrafluoroethylene dyeing liquid containing high-temperature-resistant color paste, and gradient temperature drying is performed;

[0010] 5) surface treatment: the glass fiber base cloth after dyeing treatment is immersed in a polytetrafluoroethylene surface treatment liquid containing fumed silica, and is dried at a gradient temperature to form a protective layer.

[0011] Further, in step 2), the infiltrating agent is an aqueous dispersion mixture of silane coupling agent and dimethyl silicone oil, which includes, by mass percentage, 1-1.5% silane coupling agent, 2-3% dimethyl silicone oil, and 95.5-97% pure water; the drying temperature of the drying treatment is divided into four sections, which are 120℃±5℃, 200℃±5℃, 345℃±5℃, and 150℃±5℃ cold air curtain.

[0012] Further, in step 3), the drying temperature of the pre-curing treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 285℃±5℃, and 320℃±5℃; the mass fraction of the polytetrafluoroethylene emulsion used in steps 3)-5) is all 55-60%, and the amount of emulsion used in the pre-curing treatment is 80-120g / m2; the pulling speed of the base cloth is 1-3m / min.

[0013] Further, in step 4), the drying temperature of the dyeing treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 290℃±5℃, and 330℃±5℃; the pulling speed of the base cloth is 1-3m / min.

[0014] Further, in step 4), the composition of the polytetrafluoroethylene dyeing liquid includes, by mass percentage, 84-90.3% polytetrafluoroethylene emulsion, 3-4% surfactant, 0.6-0.8% dispersant, 0.1-0.2% defoaming agent, 2-5% high-temperature color paste, and 4-6% pure water.

[0015] Further, in step 5), the drying temperature of the surface treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 290℃±5℃, and 330℃±5℃; the pulling speed of the base cloth is 1-3m / min.

[0016] Further, in step 5), the composition of the polytetrafluoroethylene surface treatment liquid includes, by mass percentage, 79.5-85.7% polytetrafluoroethylene emulsion, 10-15% hydrophobic fumed silica, 4-5% surfactant, and 0.3-0.5% dispersant.

[0017] The preparation method provided by the application removes the treating agent added on the surface of the glass fiber during the yarn making and weaving process of the glass fiber cloth through high-temperature pretreatment, facilitating the processing in the subsequent processes. The silane coupling agent and dimethyl silicone oil are used as the infiltrating agent, wherein the silane coupling agent is a reinforcing agent and can enhance the physical strength of the glass fiber cloth; the dimethyl silicone oil is a softening agent and can improve the softness of the glass fiber cloth. During the pre-curing treatment process, the polytetrafluoroethylene stock solution with a mass fraction of 55-60% is selected; the pre-curing treatment can form a pre-curing layer on the surface of the glass fiber cloth, and the main role of the pre-curing layer is to reduce the possible influence of the color paste on the glass fiber cloth in the subsequent processes. The color paste and the components therein can react with and oxidize the glass fiber, thereby reducing the physical strength of the glass fiber cloth. During the dyeing treatment, the process can be repeated multiple times according to the weight requirements of the finished product. The polytetrafluoroethylene with hydrophobic fumed silica is used as the protective layer during the surface treatment process, which can protect the dyeing layer and prevent color loss; the surface energy of the polytetrafluoroethylene and the hydrophobic fumed silica is low, and dust and dirt are not easy to adhere, so that the polytetrafluoroethylene and the hydrophobic fumed silica have good self-cleaning properties and can maintain the brightness of the overall color; the fumed silica has the characteristics of ultraviolet light absorption and infrared reflection, and can reduce the discoloration caused by long-term sunlight exposure outdoors.

[0018] A polytetrafluoroethylene building film preparation device, comprising a transmitter, an impregnation tank unit, an oven and a winding machine arranged in sequence, the number of the impregnation tank unit is at least one, the impregnation tank unit is provided with an impregnation tank, a lifting mechanism, an emulsion circulating pump and a double-sided scraper capable of adjusting height, angle and front and rear position, the lifting mechanism is used for controlling the up and down movement of the coating roller, and the emulsion circulating pump is used for circulating the emulsion in the impregnation tank, the oven is arranged above the impregnation tank unit, and the oven is divided into four temperature zones in the height direction, the first layer and the second layer at the bottom are water drying zones, the temperature is controlled at 90-200 DEG C, the third layer in the middle is a dispersant thermal volatilization zone, the temperature is controlled at 250-350 DEG C, and the fourth layer at the top is a sintering zone, the temperature is controlled at 300-400 DEG C.

[0019] Further, a plurality of tension wheels are arranged between the oven and the impregnation tank, and the pressure of the tension wheels can be adjusted in the range of 5-20 N.

[0020] Further, the double-sided scraper is arranged between the impregnation tank and the oven, the double-sided scraper comprises a sharp surface and a blunt surface, and the sharp surface and the blunt surface are switched through a rotating mechanism.

[0021] Further, a plurality of fans are arranged between the double-sided scraper and the oven.

[0022] The polytetrafluoroethylene building film preparation method and the preparation device provided by the application have the following advantages compared with the prior art.

[0023] 1) Through the pre-curing treatment, the polytetrafluoroethylene pre-curing layer is formed on the glass fiber cloth, which reduces the influence of the components in the color paste on the glass fiber cloth in the subsequent process, and affects the physical strength of the glass fiber cloth.

[0024] 2) After dyeing, surface treatment is carried out to form a polytetrafluoroethylene protective layer of hydrophobic fumed silica outside the dyeing layer, which can protect the dyeing layer and prevent color loss; the surface energy of polytetrafluoroethylene and hydrophobic fumed silica is low, and dust and dirt are not easy to adhere, so it has good self-cleaning property and can maintain the brightness of the overall color; fumed silica has the characteristics of ultraviolet light absorption and infrared reflection, which can reduce the discoloration caused by long-term sunlight exposure outdoors.

[0025] 3) In the preparation device, one or more impregnation tank units are used to treat the glass fiber cloth, which can meet different production needs; the oven is arranged above the impregnation tank, and the hanging coating method is adopted, so that the coating layer has better uniformity and flatness; a scraper is arranged to scrape and extrude the glass fiber cloth after impregnation of the emulsion to control the coating amount of the emulsion; the design of the double-sided scraper can meet different coating needs; the design of the multi-section oven makes the glass fiber cloth after hanging coating of the emulsion gradually experience processes such as moisture drying, solvent volatilization and polytetrafluoroethylene sintering, so that the coating layer is more dense, uniform and firm. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the preparation device of the present application under the condition of double impregnation tanks.

[0027] Figure 2 It is a structural schematic diagram of the double-sided scraper.

[0028] Among them, 1-oven; 101-first layer; 102-second layer; 103-third layer; 104-fourth layer; 2-transmitter; 3-tension wheel; 4-impregnation tank unit; 401-impregnation tank; 402-coating roller; 403-double-sided scraper; 413-blunt surface; 423-sharp surface; 5-fan; 6-drawing machine; 7-winding machine; 8-tail gas treatment device. DETAILED DESCRIPTION

[0029] The present application will be further described below through specific examples. However, these examples are only used to illustrate the present application and not to limit the scope of the present application.

[0030] Example 1

[0031] A preparation method of a polytetrafluoroethylene building membrane, the preparation method comprising the following steps:

[0032] 1) Pretreatment: 3-6 micron glass fiber yarn is selected to weave a glass fiber cloth with a unit area mass of 600 g / m2; the glass fiber base cloth is treated at high temperature to remove the surface treatment agent; the glass fiber cloth is sent from bottom to top into the oven at a speed of 2.5 m / min, and the oven heating mode is selected to be multi-stage heating, and the temperatures from bottom to top are 120℃, 200℃, 340℃, hot air curtain, respectively; the treatment agent added to the surface of the glass fiber during the yarn making and cloth weaving process is removed by high temperature heating, facilitating the processing of subsequent processes.

[0033] 2) Infiltration treatment: the pretreated glass fiber base cloth is immersed in an infiltrating agent containing silane coupling agent and dimethyl silicone oil, and is dried after infiltration; the glass fiber cloth is immersed in the infiltrating agent at a speed of 2.5 m / min, and is then sent from bottom to top into the oven for drying, and the temperatures from bottom to top are 120℃, 200℃, 345℃, 150℃ cold air curtain, respectively. The infiltrating agent is an aqueous dispersion mixture of silane coupling agent and dimethyl silicone oil, and the mass ratio of silane coupling agent, dimethyl silicone oil and pure water is 1:2.4:96.6. The silane coupling agent is a reinforcing agent that can enhance the physical strength of the glass fiber cloth; the dimethyl silicone oil is a softening agent that can improve the softness of the glass fiber cloth.

[0034] 3) Pre-curing treatment: the glass fiber base cloth after infiltration treatment is immersed in a polytetrafluoroethylene emulsion, and is dried at a gradient temperature to form a pre-cured layer; the glass fiber cloth is immersed in the polytetrafluoroethylene emulsion at a speed of 1.9 m / min, and is sent from bottom to top into the oven for drying, and the temperatures from bottom to top are 100℃, 120℃, 285℃, 320℃, respectively. The polytetrafluoroethylene emulsion selected is a polytetrafluoroethylene stock solution with a mass fraction of 56%. This treatment can form a pre-cured layer on the surface of the glass fiber cloth, and in this embodiment, the unit area usage of the emulsion in the pre-curing treatment is 100 g / m2; the pre-cured layer can reduce the possible influence of the color paste on the glass fiber cloth in the subsequent process, and the color paste and its components may react with the glass fiber to be oxidized, thereby reducing the physical strength of the glass fiber cloth.

[0035] 4) Dyeing treatment: the glass fiber base cloth after pre-curing treatment is immersed in a polytetrafluoroethylene dyeing liquid containing high-temperature resistant color paste, and is dried at a gradient temperature; the glass fiber cloth is immersed in the polytetrafluoroethylene dyeing liquid at a speed of 2.3 m / min, and is sent from bottom to top into the oven for drying, and the temperatures from bottom to top are 100℃, 120℃, 290℃, 330℃, respectively, and this process is repeated multiple times according to the weight requirements of the finished product. The components of the polytetrafluoroethylene dyeing liquid are polytetrafluoroethylene emulsion with a mass fraction of 56%, polyethylene glycol octylphenyl ether surfactant, polyammonium carboxylate dispersant, methyl silicone resin defoaming agent, high-temperature color paste and pure water, and the mass ratio is 85.5:3.5:0.8:0.2:4:6. In this embodiment, the unit area usage of the dyeing liquid in the dyeing treatment is 180 g / m2.

[0036] 5) Surface treatment: after dyeing treatment, the glass fiber fabric is immersed in a polytetrafluoroethylene surface treatment liquid containing fumed silica, and is dried by gradient temperature to form a protective layer. The glass fiber fabric is immersed in the polytetrafluoroethylene surface treatment liquid at a speed of 2.3 m / min, and is sent to the oven from bottom to top for drying, and the temperature from bottom to top is 100℃, 120℃, 290℃, 330℃, respectively. The hydrophobic fumed silica polytetrafluoroethylene serves as a protective layer, which can protect the dyed layer and prevent color loss. The surface energy of polytetrafluoroethylene and hydrophobic fumed silica is low, so it is not easy to attach dust and dirt, has good self-cleaning property, and can maintain the brightness of the overall color. The fumed silica has the characteristics of ultraviolet light absorption and infrared reflection, which can reduce the discoloration caused by long-term sunlight exposure. In this embodiment, the amount of treatment liquid per unit area in the surface treatment is 40 g / m2.

[0037] A preparation device of polytetrafluoroethylene building membrane, comprising a sender 2, an immersion tank unit 4, an oven 1 and a winding machine 7 arranged in sequence, wherein the number of the immersion tank unit 4 is at least one; in this embodiment, a double immersion tank structure is adopted, which comprises a first immersion tank unit and a second immersion tank unit. Each of the immersion tank units 4 is provided with an immersion tank 401, a lifting mechanism (not shown), an emulsion circulating pump (not shown), and a double-sided scraper 403 with adjustable height, angle and front and rear position; the lifting mechanism is used to control the up and down movement of a coating roller 402, and the emulsion circulating pump is used to circulate the emulsion in the immersion tank 401; the oven 1 is arranged above the immersion tank unit 4, and the oven 1 is divided into four temperature zones in the height direction: the first layer 101 and the second layer 102 at the bottom are water drying zones, and the temperature is controlled at 90-200℃; the third layer 103 in the middle is a dispersant thermal volatilization zone, and the temperature is controlled at 250-350℃; and the fourth layer 104 at the top is a sintering zone, and the temperature is controlled at 300-400℃. The oven 1 is connected with a tail gas treatment device 8, and the tail gas generated during the drying and sintering process is discharged after treatment, which is more environmentally friendly and safe. A plurality of tension wheels 3 are arranged between the oven 1 and the immersion tank 401, and the pressure of the tension wheels 3 can be adjusted in the range of 5-20 N. The double-sided scraper 403 is arranged between the immersion tank 401 and the oven 1, and the double-sided scraper 403 comprises a sharp surface 423 and a blunt surface 413. The scraper can scrape off the excess emulsion on the surface of the fabric, control the coating amount of the emulsion, and the sharp surface has a stronger extrusion effect on the fabric surface, which can scrape off more emulsion. When the required emulsion coating amount is low, the sharp surface 423 is selected, otherwise the blunt surface 413 is selected, and the sharp surface 423 and the blunt surface 413 are switched by a rotating mechanism. A plurality of fans 5 are arranged between the oven 1 and the double-sided scraper 403, which can blow away the heat on the glass fiber fabric quickly, and also can accelerate the volatilization of the solvent.

[0038] The working flow of the preparation device is as follows:

[0039] 1) The glass fiber cloth is installed on the transmitter 2 and connected with the traction rope, the transmitter 2 is provided with an edge correction device and can set the transmission speed and tension.

[0040] 2) The glass fiber cloth is sent from the transmitter 2 to the storage rack to continuously produce without stopping; the storage rack can set the tension.

[0041] 3) The glass fiber cloth enters the first immersion tank 401 from the storage rack; the immersion tank 401 can be externally connected with a polytetrafluoroethylene emulsion barrel to add emulsion, and can be freely lifted by oil pressure power; the emulsion circulating pump can be installed in the immersion tank 401 to circulate the emulsion in the tank to prevent stratification or precipitation of the emulsion.

[0042] 4) The double-sided scraper 403 is installed on both sides of the glass fiber cloth in the immersion tank 401, which can select the scraper form, height, angle and front and rear position by rotation, and the double-sided scraper 403 performs surface scraping, coating and extrusion on the glass fiber cloth after immersion emulsion to control the coating amount of the emulsion.

[0043] 5) The glass fiber cloth after hanging coating is pulled upward into the oven 1, which can set the heating temperature and view the real-time temperature, and the temperature sensor in the oven 1 detects the real-time temperature, which is automatically controlled by the computer. The oven is divided into four sections from bottom to top, the first layer 101 and the second layer 102 at the bottom are used for evaporating water; the third layer 103 in the middle is used for volatilizing surfactants, dispersants and other solvents; and the fourth layer 104 at the top is used for sintering polytetrafluoroethylene. The heating mode: the bottom drying area and the middle thermal volatilization area use electric heating tube heating, and the top sintering area uses gas heating.

[0044] 6) The sintered glass fiber cloth is pulled downward through the tension wheel 3 into the second immersion tank 401, and the emulsion in the second immersion tank can be the same as that in the first immersion tank to realize secondary coating and increase the density of the coating; or it can be different from the first immersion tank to realize the continuity of the film material preparation process; the specific adjustment can be made according to the actual production needs.

[0045] 7) The coated glass fiber cloth is pulled by the traction machine 6, and is wound by the winding machine 7 after edge correction.

[0046] 8) Different specifications of products need to repeat steps 1) to 7) several times, such as in this embodiment, since the immersion treatment, pre-solidification treatment, dyeing treatment and surface treatment are required, when the emulsion in the first immersion tank is the same as that in the second immersion tank, at least four times of the above steps are required, and finally the polytetrafluoroethylene building film material is obtained.

[0047] Example 2

[0048] In this embodiment, the glass fiber cloth with a unit area mass of 700 g / m2 is selected, the pre-cured treatment unit area dosage is 120 g / m2, the dyeing treatment unit area dosage is 300 g / m2, and the surface treatment unit area dosage is 80 g / m2.

[0049] Comparative Example 1

[0050] The glass fiber cloth with a unit area mass of 600 g / m2 is selected, and in the pre-cured layer coating step, a sharp-faced scraper with an angle of 90 degrees is selected, and the front and rear positions of the scraper are adjusted to the frontmost position and closely adhere to the cloth surface to achieve the maximum scraping and extrusion of the cloth surface, and the pre-cured layer unit area mass is 50 g / m2. The other steps are the same as those in Example 1.

[0051] Comparative Example 2

[0052] The glass fiber cloth with a unit area mass of 600 g / m2 is selected, and no pre-cured treatment is performed, and the other steps are the same as those in Example 1.

[0053] Comparative Example 3

[0054] The glass fiber cloth with a unit area mass of 600 g / m2 is selected, and no surface treatment is performed, and the other steps are the same as those in Example 1.

[0055] Performance test results:

[0056]

[0057] The above embodiments are only used to illustrate the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and all equivalent technical solutions also belong to the scope of the present application. The patent protection scope of the present application should be defined by the claims.

Claims

1. A method of making a polytetrafluoroethylene building membrane, characterized by: The preparation method comprises the following steps: 1) Pretreatment: high temperature treatment is performed on the glass fiber base cloth to remove the surface treatment agent; 2) Infiltration treatment: the pretreated glass fiber base cloth is immersed in an infiltrating agent containing silane coupling agent and dimethyl silicone oil, and after infiltration, drying treatment is performed; 3) Pre-curing treatment: the glass fiber base cloth after the infiltration treatment is immersed in a polytetrafluoroethylene emulsion, and gradient temperature drying is performed to form a pre-cured layer; 4) Dyeing treatment: the glass fiber base cloth after the pre-curing treatment is immersed in a polytetrafluoroethylene dyeing liquid containing high-temperature-resistant color paste, and gradient temperature drying is performed; 5) Surface treatment: the glass fiber base cloth after the dyeing treatment is immersed in a polytetrafluoroethylene surface treatment liquid containing fumed silica, and gradient temperature drying is performed to form a protective layer.

2. A method of making a polytetrafluoroethylene building membrane as claimed in claim 1, characterised in that: In step 2), the infiltrating agent is an aqueous dispersion mixed solution of silane coupling agent and dimethyl silicone oil, and by mass percentage, it comprises: 1-1.5% of silane coupling agent, 2-3% of dimethyl silicone oil and 95.5-97% of pure water; the drying temperature of the drying treatment is divided into four sections, which are 120℃±5℃, 200℃±5℃, 345℃±5℃ and 150℃±5℃ cold air curtain.

3. A method of making a polytetrafluoroethylene building membrane as defined in claim 1, characterized in that: In step 3), the drying temperature of the pre-curing treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 285℃±5℃ and 320℃±5℃; the mass fraction of the polytetrafluoroethylene emulsion used in steps 3)-5) is all 55-60%, and the amount of the emulsion used in the pre-curing treatment is 80-120g / m2; the pulling speed of the base cloth is 1-3m / min.

4. The method for preparing a polytetrafluoroethylene architectural membrane as described in claim 1, characterized in that: In step 4), the drying temperature of the dyeing treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 290℃±5℃ and 330℃±5℃; the pulling speed of the base cloth is 1-3m / min.

5. The method for preparing a polytetrafluoroethylene architectural membrane as described in claim 1, characterized in that: In step 4), the composition of the polytetrafluoroethylene dyeing liquid comprises, by mass percentage, 84-90.3% of polytetrafluoroethylene emulsion, 3-4% of surfactant, 0.6-0.8% of dispersant, 0.1-0.2% of defoaming agent, 2-5% of high-temperature-resistant color paste and 4-6% of pure water.

6. A method of making a polytetrafluoroethylene building membrane as defined in claim 1, characterized by: In step 5), the drying temperature of the surface treatment is divided into four sections, which are 100℃±5℃, 120℃±5℃, 290℃±5℃ and 330℃±5℃; the pulling speed of the base cloth is 1-3m / min.

7. A method of making a polytetrafluoroethylene building membrane as defined in claim 1, wherein: In step 5), the composition of the polytetrafluoroethylene surface treatment liquid comprises, by mass percentage, 79.5-85.7% of polytetrafluoroethylene emulsion, 10-15% of hydrophobic fumed silica, 4-5% of surfactant and 0.3-0.5% of dispersant.

8. An apparatus for producing a polytetrafluoroethylene building membrane, characterized by: The impregnation device comprises a transmitter, an impregnation tank unit, an oven and a winding machine arranged in sequence, characterized in that the number of the impregnation tank unit is at least one; the impregnation tank unit is provided with an impregnation tank, a lifting mechanism, an emulsion circulating pump and a double-sided scraper capable of adjusting the height, angle and front and back positions; the lifting mechanism is used for controlling the up and down movement of a coating roller; the emulsion circulating pump is used for circulating the emulsion in the impregnation tank; the oven is arranged above the impregnation tank unit; the oven is divided into four temperature zones in the height direction, the first layer and the second layer at the bottom are moisture drying zones with the temperature controlled at 90-200 DEG C; the third layer in the middle is a dispersant thermal volatilization zone with the temperature controlled at 250-350 DEG C; and the fourth layer at the top is a sintering zone with the temperature controlled at 300-400 DEG C.

9. An apparatus for producing a polytetrafluoroethylene building membrane as claimed in claim 8, characterized in that: A plurality of tension wheels are arranged between the oven and the impregnation tank, and the pressure of the tension wheels can be adjusted in the range of 5-20 N; a plurality of fans are arranged between the oven and the double-sided scraper below the oven.

10. The apparatus for producing a polytetrafluoroethylene building membrane according to claim 8, wherein: The double-sided scraper is arranged between the impregnation tank and the oven, and comprises a sharp surface and a blunt surface which are switched by a rotating mechanism.

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