A rapid prototyping heat-resistant film, preparation method and application

Abstract

The present invention discloses a rapid prototyping heat-resistant film and a preparation method thereof. The steps include: uniformly dispersing a reinforcing filler and ground fibers in silicone rubber to obtain a mixture; performing vacuum kneading on the mixture; and then calendering the kneaded and dispersed mixture to obtain a preliminary formed film. Finally, the preliminary formed film is cured to obtain a heat-resistant film. The heat-resistant film obtained by the present invention can replace the traditional air-sprayed silicone rubber heat-resistant coating construction, and is particularly suitable for application to aircraft surfaces to achieve the purpose of protecting against aerodynamic heat. The obtained structural parts have good mechanical, thermophysical properties, and ablation resistance. At the same time, compared with the air-sprayed construction of traditional heat-resistant coatings, the present invention can avoid the use of a large amount of solvents and significantly shorten the construction period. This has far-reaching significance for the rapid delivery of future heat-resistant products and the promotion of environmental protection.

Description

Technical Field

[0001] The invention relates to a heat-proof film, a preparation method and application, and belongs to the technical field of surface coatings. Background Art

[0002] Thermal protection systems are a key factor in determining the success or failure of aircraft. Currently, silicone rubber thermal protection coatings are widely used to protect the exterior of aircraft in medium- to high-heat flux environments. However, existing silicone rubber thermal protection coatings primarily utilize condensation-type silicone rubber systems, which cure via dealcoholization and condensation, resulting in a relatively long curing cycle. Silicone rubber thermal protection coatings are typically applied via spraying or brushing. During the coating process, the viscosity of the coating constantly fluctuates, making the coating thickness uncontrollable. To ensure the silicone rubber thermal protection coating meets design requirements, significant polishing and repairing are required. These factors significantly impact the efficient and high-quality delivery of thermal protection products. Summary of the Invention

[0003] The present invention aims to overcome these drawbacks by providing a rapid-prototyping heat-resistant film and its preparation method. This method addresses the technical issues of traditional air-sprayed silicone rubber heat-resistant coatings, such as long application cycles, organic solvent contamination, and difficulty controlling coating thickness. The heat-resistant film obtained by this invention can replace traditional air-sprayed silicone rubber heat-resistant coatings, while avoiding the use of large amounts of solvents and significantly shortening the application cycle. This has far-reaching implications for the rapid delivery of future heat-resistant products and for promoting environmental protection.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] A method for preparing a rapid prototyping heat-resistant film, comprising:

[0006] (1) uniformly dispersing the reinforcing filler and the ground fiber in the silicone rubber I to obtain a mixture A1;

[0007] (2) Mixture A1, a porcelain-forming filler, a curing agent I, a lightweight filler, a volatile viscosity reducer, and a curing inhibitor are vacuum kneaded, a sample is taken from the mixture obtained during the vacuum kneading process, the sample is heat-treated, and whether the vacuum kneading is completed is determined based on the mass change rate of the sample after the heat treatment. After the vacuum kneading is completed, mixture A2 is obtained;

[0008] (3) Spreading the mixture A2 between two layers of polytetrafluoroethylene films and calendering the mixture A2 to obtain a preliminary formed film;

[0009] (4) Curing the preliminarily formed film to obtain a heat-resistant film.

[0010] Furthermore, in step (1), the silicone rubber I is a linear random copolymer of silazane and siloxane, and the structural formula of the silicone rubber I is as follows:

[0011]

[0012] Among them, x=3%~5% (x+y+z), y=5%~8% (x+y+z);

[0013] The reinforcing filler is one or a combination of carbon black, calcium carbonate or white carbon black;

[0014] The milled fiber is one or more of milled glass fiber and milled carbon fiber;

[0015] In step (1), the mass ratio of silicone rubber I, reinforcing filler and ground fiber is 100:10-30:5-20;

[0016] The specific method for uniformly dispersing the reinforcing filler and the ground fiber in the silicone rubber is to grind with three rollers for 2 to 4 times or knead and disperse for 20 to 40 minutes to obtain a mixture A1 that is uniform in color and free of particles when observed with the naked eye.

[0017] Furthermore, in step (2):

[0018] The porcelain-forming filler is one or a combination of more than one of boron oxide, boron carbide or talc;

[0019] Curing agent I is a platinum catalyst or chloroplatinic acid;

[0020] The lightweight filler is one or a combination of glass microspheres or phenolic microspheres; the isostatic strength of the glass microspheres and phenolic microspheres is ≥2MPa;

[0021] The volatile viscosity reducer is dichloromonofluoroethane, or a mixture of dichloromonofluoroethane and n-heptane;

[0022] The curing inhibitor is an alkynyl alcohol.

[0023] Furthermore, in step (2), the mass ratio of the mixture A1, the porcelain-forming filler, the lightweight filler, the volatile viscosity reducer, the curing agent I and the curing inhibitor is 100:30-50:15-30:2-15:0.4-1:0.2-0.5;

[0024] In the volatile viscosity reducer, the mass ratio of monofluorodichloroethane to n-heptane is 100:0-3;

[0025] The porcelain filler is a powder obtained by screening through a 300-mesh vibrating screen.

[0026] Furthermore, in step (2), vacuum kneading is carried out in a vertical kneader, the stirring paddle used for vacuum kneading is a frame type, and the vacuum degree of vacuum kneading is -0.01 MPa;

[0027] After vacuum kneading for 15 to 30 minutes, a sample is taken out from the mixture obtained during the vacuum kneading process and the sample is heat-treated at 60°C for 15 minutes. When the mass change rate of the sample after heat treatment is less than 1%, the vacuum kneading is completed to obtain mixture A2.

[0028] Furthermore, in step (3), the thickness of the polytetrafluoroethylene film is 0.3 to 0.6 mm;

[0029] In step (3), the mixture A2 is spread between two layers of polytetrafluoroethylene membranes, and the specific method for calendering the mixture A2 is to set the gap between the calendering rollers of the parallel calendering machine to 1 to 5 mm, and repeat the calendering 1 to 3 times;

[0030] In step (4), the specific method for curing the preliminary formed film is to heat and cure the preliminary formed film at a high temperature of 100-120° C. for 2 hours.

[0031] Furthermore, in step (3), the mixture A2 is first placed in a vacuum box and continuously subjected to vacuum negative pressure treatment at a vacuum degree of -0.01 to -0.03 MPa for 1 to 3 hours, and then the mixture A2 is spread between two layers of polytetrafluoroethylene films and calendered to obtain a preliminary formed film.

[0032] A rapid prototyping heat-proof film is obtained by adopting the above preparation method.

[0033] An application of a rapid prototyping heat-resistant film, comprising:

[0034] Apply adhesive with a thickness of 200 to 400 μm on the surface of the metal substrate;

[0035] Pressing the heat-resistant film obtained by the above preparation method onto the adhesive scraped on the surface of the metal substrate, and squeezing out the remaining adhesive;

[0036] After the metal substrate and the heat-proof film are wrapped with a plastic film, a vacuum pressure treatment is performed to obtain a heat-proof structural component.

[0037] Furthermore, in the application of the above-mentioned rapid prototyping heat-resistant film, the adhesive includes uniformly mixed silicone rubber II, tackifier and curing agent II, and the mass ratio of silicone rubber II, tackifier and curing agent II is 100:5-15:3-11;

[0038] Silicone rubber II is epoxy modified vinyl silicone rubber with a molecular weight of 1×10 5 ~1.5×10 5 ;

[0039] The tackifier is one or a combination of white carbon black, red iron oxide or talc;

[0040] The curing agent II is a mixture of chloroplatinic acid and hydrogen-containing silicone oil; the mass ratio of chloroplatinic acid to silicone rubber II is 0.3-0.5:100, and the mass ratio of hydrogen-containing silicone oil to silicone rubber II is 1:5-15.

[0041] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0042] (1) Compared with spray-on silicone rubber heat-resistant coatings, the heat-resistant film of the present invention avoids adding a large amount of organic solvents during the preparation process, greatly reducing VOC emissions and safety hazards during the preparation process of the heat-resistant coating. The heat-resistant film obtained by the present invention can be used to replace the traditional air-sprayed external heat-resistant coating on aircraft;

[0043] (2) When the heat-resistant film obtained by the present invention is applied to the surface of a metal substrate, it has the advantages of a short construction period and a long finishing period, which saves the time required for grinding and finishing due to uneven thickness caused by curing shrinkage or changes in coating viscosity during the spraying of the heat-resistant coating, and reduces the amount of organic solvent used in the spraying, thereby improving the safety of the heat-resistant layer construction and meeting the development requirements of the coating industry for environmentally friendly materials;

[0044] (3) The heat-resistant film prepared by the method of the present invention has a density of 0.8g / cm 3 Below, the tensile strength is above 3.0MPa, the tensile strain at break is greater than 30%, and when the thickness of 5mm heat-resistant film is applied to the surface of 4mm aluminum substrate, the maximum cold wall heat flux is 1065kW / m 2 Under typical heat flow conditions with an enthalpy of 3100 kJ / kg and a total duration of not less than 500 seconds, the back temperature is not higher than 220°C, and the coating surface erosion is less than 1 mm;

[0045] (4) Compared with silicone rubber-based heat-resistant coatings, the heat-resistant film material provided by the present invention can be used in thermal environments with higher enthalpy values ​​and longer working times. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The surface temperature and back temperature variation data of the heat-proof structural component obtained in Example 1 of the present invention in the wind tunnel test;

[0047] Figure 2 The surface temperature and back temperature variation data of the heat-proof structural component obtained in Example 2 of the present invention in the wind tunnel test;

[0048] Figure 3 This is a photograph of the surface morphology of the heat-resistant structural component obtained in Example 1 of the present invention after the wind tunnel test;

[0049] Figure 4 This is a photograph of the surface morphology of the heat-resistant structural component obtained in Example 2 of the present invention after the wind tunnel test. DETAILED DESCRIPTION

[0050] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0051] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0052] The present invention aims to provide a method for preparing and applying heat-proof film, in order to replace the traditional air spraying construction process, save the curing time of the spray coating and the finishing work time, and improve the construction efficiency of heat-proof products. The present invention provides a rapid prototyping heat-proof film and a preparation method thereof, wherein the mixture obtained by uniformly dispersing reinforcing fillers and ground fibers in silicone rubber, ceramic fillers, curing agents, lightweight fillers, volatile viscosity reducers and curing inhibitors are vacuum kneaded, and the kneaded and dispersed mixture is calendered to obtain a preliminary molded film, and finally the preliminary molded film is cured to obtain a heat-proof film. The heat-proof film obtained by the present invention can replace the traditional air spraying silicone rubber heat-proof coating construction, and is particularly suitable for application to aircraft surfaces to achieve the purpose of protecting aerodynamic heat. The obtained structural parts have good mechanical, thermal physical properties and ablation resistance, and are at a maximum of 1065kW / m 2 In an aerodynamic environment with a recovery enthalpy of 3100kJ / kg and a total time of 526s, the ablation amount is less than 1mm. At the same time, compared with the air spray construction of traditional thermal protection coatings, it avoids the use of large amounts of solvents and the construction period is greatly shortened, which has far-reaching significance for the rapid delivery of future thermal protection products and the promotion of environmental protection.

[0053] In a preferred real-time mode, the present invention comprises the following steps:

[0054] (1) Mixing the silicone rubber I: reinforcing filler: ground fiber in a weight ratio of 100:10-30:5-20, grinding the reinforcing filler and ground fiber uniformly in the silicone rubber I using a three-roll mill for 2-4 times or kneading and dispersing for 20-40 minutes until the mixture is uniform in color and free of particles, thereby preparing a mixture A1;

[0055] (2) According to the mass ratio of monofluorodichloroethane:n-heptane=100:0-3, monofluorodichloroethane and n-heptane are mixed to obtain a volatile viscosity reducer; the porcelain filler powder is sieved with a 300-mesh vibrating screen before mixing; according to the weight ratio of mixture A1:porcelain filler:light filler:volatile viscosity reducer:curing agent I:curing inhibitor=100:30-50:15-30:2-15:0.4-1:0.2-0.5, the mixture is mixed and vacuum kneaded and dispersed in a vertical kneader for 15-30 minutes, the stirring paddle is a frame type, the vacuum degree is -0.01MPa, until the color of the mixture is uniform, 10-20g is taken out, the weight is recorded, and then heated at 60°C for 15 minutes. If the mass change rate is within 1%, it is considered that the dispersion is complete, and the mixture is taken out to obtain mixture A2.

[0056] (3) Mixture A2 is subjected to vacuum negative pressure treatment in a vacuum box at a vacuum degree of -0.02 MPa for 2 hours to reduce the porosity of the mixture, and then placed between two layers of polytetrafluoroethylene membranes with a thickness of 0.3-0.6 mm. A parallel double-roll calender is used for calendering. The roller spacing is set according to the actual thickness of the film, for example, the roller spacing is set to 2 mm, the roller speed is set to 2 r / min, and calendering is performed 1-3 times. After calendering, it is placed in a 100-120°C drying tunnel for 2 hours to cure. After curing, it is cut to obtain a heat-resistant film with a thickness equal to the roller spacing;

[0057] (4) Silicone rubber II: tackifier: curing agent II are mixed in a ratio of 100:5-15:3-11, stirred and dispersed, and then scraped onto the surface-treated metal substrate with a scraping thickness of 200-400 μm; a heat-resistant film is pressed on the surface of the substrate coated with the adhesive, and the remaining glue is squeezed out by repeatedly pressing, and the entire metal substrate and the surface of the heat-resistant film are covered with a plastic PE film, and a latex tube is connected to the PE film and led to a vacuum pump; the vacuum pump is turned on, and after continuous vacuum pressure for 8 hours, the PE film is peeled off to obtain a heat-resistant structural part.

[0058] Specifically, silicone rubber I is a linear random copolymer of silazane and siloxane, and its specific structure is as follows:

[0059]

[0060] Among them, x=3%~5% (x+y+z), y=5%~8% (x+y+z);

[0061] The reinforcing filler is carbon black, calcium carbonate or white carbon black;

[0062] The milled fiber is one or more of milled glass fiber and milled carbon fiber;

[0063] The porcelain-forming filler is one or more of boron oxide, boron carbide and talc, which plays a dimensional role;

[0064] The lightweight filler is one or more of high-strength glass microspheres and phenolic microspheres. The isostatic strength of the glass microspheres and phenolic microspheres is ≥2MPa to avoid breakage during the vacuum kneading process, which affects the product performance.

[0065] The volatile viscosity reducer is monofluorodichloroethane or a mixture of monofluorodichloroethane and n-heptane. The present invention uses a volatile viscosity reducer to reduce the viscosity of the mixture and improve its dispersion effect. At the same time, the viscosity reducer gradually evaporates during the kneading and dispersion process. The mass change rate of the sample after heat treatment can ensure that the viscosity reducer is basically volatilized and will not remain in the system as volatile small molecules to affect the ablation morphology and reduce the heat release efficiency.

[0066] The curing inhibitor is an alkynyl alcohol, which is used to inhibit the curing of the resin at room temperature and prolong the process operation time. The present invention uses an alkynyl alcohol to avoid the curing of the resin during the vacuum kneading process in step (2), thereby ensuring that the mixture is first calendered and initially formed in the subsequent steps and finally cured at a high temperature. The uniformity of the film thickness is maximized by calendering, and this effect is also difficult to achieve by the spraying method in the existing technology.

[0067] Specifically, silicone rubber II is epoxy-modified vinyl silicone rubber with a molecular weight of 1×10 5 ~1.5×10 5 ;

[0068] The tackifier is one or more of white carbon black, red iron oxide, and talcum powder; red iron oxide also has a dyeing effect;

[0069] Curing agent II is a mixture of chloroplatinic acid and hydrogen-containing silicone oil, wherein chloroplatinic acid is a cross-linking reaction catalyst and hydrogen-containing silicone oil is a cross-linking agent.

[0070] The heat-proof film obtained by the invention is used to replace the silicone rubber heat-proof coating constructed by traditional air spraying, and is particularly suitable for long-term (500s) and high-enthalpy (3000kJ / kg and above) thermal environments.

[0071] Example 1

[0072] (1) 100 g of silicone rubber, 10 g of white carbon black, and 10 g of ground glass fiber were coarsely mixed and then ground twice with a three-roll mill until the mixture became translucent to prepare mixture A1;

[0073] (2) Prepare a volatile viscosity reducer by mixing 100 g of monofluorodichloroethane with 0.5 g of n-heptane; prepare a mixture of 30 g of talc and 10 g of boron oxide powder, and then sieve the mixture through a 300 mesh vibratory screen to obtain a ceramic filler powder; prepare a mixture of 100 g of mixture A1, add 40 g of the above powder, 20 g of phenolic hollow microspheres, 10 g of the above volatile viscosity reducer, 0.5 g of chloroplatinic acid, and 0.25 g of alkynylcyclohexanol into a kneader, and knead and disperse under vacuum for 15 minutes. Take out 10 g of the sample and heat it in an oven at 60°C for 15 minutes. If the mass change is within 1%, stop kneading and dispersing. If the mass change is greater than 1%, continue kneading and dispersing for 5 minutes until the mass change is less than 1%. Stop the vacuum kneading and dispersing to obtain mixture A2.

[0074] (3) Mixture A2 was subjected to continuous vacuum negative pressure treatment in a vacuum chamber for 2 h, with a vacuum degree of -0.02 MPa. After the vacuum treatment, the mixture A2 was placed between two layers of 0.3 mm thick polytetrafluoroethylene cloth and rolled once using a parallel double-roll calender with a roller spacing of 2 mm. After the rolling was completed, the mixture was heated at 100°C for 2 h to cure. After the curing was completed, the mixture was cut to obtain a 2 mm thick heat-resistant film.

[0075] (4) After mixing 10 g of epoxy modified silicone rubber, 1 g of white carbon black, 0.05 g of chloroplatinic acid, and 0.95 g of hydrogenated silicone oil, the mixture was scraped and applied to the surface of the substrate to be bonded. The heat-resistant film was pressed on the surface of the substrate coated with the adhesive, and the remaining adhesive was squeezed out by repeated pressing. The entire metal substrate and the surface of the heat-resistant film were covered with a plastic PE film. A latex tube was connected to the PE film, and then a vacuum pump was connected. The vacuum pump was turned on and vacuum pressure was continuously applied for 8 hours. The PE film was then peeled off to obtain a heat-resistant structural component.

[0076] Example 2

[0077] (1) 100 g of silicone rubber, 20 g of white carbon black, and 15 g of ground carbon fiber were coarsely mixed and then ground twice with a three-roll mill until the mixture became translucent to prepare mixture A1;

[0078] (2) Prepare a volatile viscosity reducer by mixing 100 g of monofluorodichloroethane with 3 g of n-heptane for later use; mix 30 g of talc with 20 g of boron carbide powder and sieve through a 300 mesh vibratory screen to obtain a ceramic filler powder for later use; take 100 g of mixture A1, add 50 g of the ceramic filler powder, 30 g of high-strength hollow glass microspheres, 8 g of the volatile viscosity reducer, 0.5 g of platinum catalyst, and 0.25 g of alkynylcyclohexanol into a kneader cylinder, and knead and disperse under vacuum for 15 minutes. Take out 10 g of the sample and heat it in an oven at 60°C for 15 minutes. If the mass change rate is within 1%, stop kneading and dispersing. If the mass change rate is greater than 1%, continue kneading and dispersing for 5 minutes until the mass change is less than 1%. Stop the vacuum kneading and dispersing to obtain mixture A2.

[0079] (3) Mixture A2 was subjected to continuous vacuum negative pressure treatment in a vacuum chamber for 2 h, with a vacuum degree of -0.02 MPa. After the vacuum treatment, the mixture A2 was placed between two layers of 0.3 mm thick polytetrafluoroethylene cloth and rolled once using a parallel double-roll calender with a roller spacing of 5 mm. After rolling, the mixture was placed in a 120°C drying oven for 2 h for curing. After curing, the mixture was cut to obtain a 5 mm thick heat-resistant film.

[0080] (4) After mixing 10 g of epoxy-modified silicone rubber, 1.2 g of red iron oxide, 0.03 g of chloroplatinic acid, and 1 g of hydrogenated silicone oil, the mixture was scraped onto the surface of a 4 mm thick aluminum substrate to be bonded. A 5 mm thick heat-resistant film was pressed onto the surface of the substrate coated with the adhesive, and the remaining adhesive was squeezed out by repeated pressing. The entire surface of the aluminum substrate and the heat-resistant film was covered with a plastic PE film. A latex tube was connected to the inside of the PE film and led to a vacuum pump. The vacuum pump was turned on and vacuum pressure was continuously applied for 8 h. The PE film was then peeled off to obtain a heat-resistant structural component.

[0081] The test results of the heat-resistant structural parts obtained in Examples 1 and 2 are shown in Table 1, wherein the wind tunnel test results for testing the ablation heat-resistant performance of Example 1 are shown in Table 1. Figure 1 and Figure 3 As shown in the wind tunnel test results of Example 2 for testing the ablation heat protection performance, Figure 2 and Figure 4 shown.

[0082] Table 1 Test results of heat-resistant films obtained in Examples 1 and 2

[0083]

[0084] Comparative Example 1:

[0085] According to the material ratios in Example 1, a heat-resistant coating was prepared on a metal plate by conventional air spraying. The specific process was as follows: 100g of silicone rubber, 10g of white carbon black, and 10g of ground glass fiber were coarsely mixed and then ground twice on a three-roll mill until the mixture became translucent to obtain mixture A1; 100g of mixture A1 was taken, 30g of talc powder, and 10g of boron oxide powder, and ground on a three-roll mill for 4-5 times to obtain mixture A2; 20g of phenolic hollow microspheres and 40g of 120# solvent gasoline were added, and the mixture was dispersed in a sealed state using a high-speed dispersant for 30 minutes to obtain heat-resistant coating component A. The heat-resistant coating component A was mixed with 0.5g of chloroplatinic acid and 150g of 120# solvent gasoline, dispersed in a high-speed dispersant for 5 minutes, and then air sprayed on the metal plate to prepare a heat-resistant coating. Since the volatile viscosity reducer, curing inhibitor and solvent gasoline in the system are all volatile substances, neither the sprayed heat-resistant coating nor the heat-resistant film contains these substances. Therefore, it can be considered that the heat-resistant material systems prepared by Example 1 and Example 1 are the same, and only the process methods are different.

[0086] The heat-resistant coating prepared according to the above method has a density of 0.58-0.68 g / cm 3 , thermal conductivity 0.13-0.15W / m·K, specific heat capacity 1.3-1.4J / g·K, tensile strength 2.88-3.15MPa, elongation at break 31-42%, complete curing takes about 24 hours or more, quality retention rate at 600℃ is 55.8%, and quality retention rate at 800℃ is 63.4%.

[0087] Therefore, the process method used in the present invention greatly reduces the curing time under the premise of having little impact on the performance compared to the air spray process, saves the time for adjusting the coating appearance thickness after spraying construction, and avoids the use of organic solvents in the spraying process. The volatile viscosity reducer of the present invention is also completely evaporated during the vacuum kneading process, which is a green and environmentally friendly preparation method. In view of the fact that most construction units now require to avoid the use of flammable and explosive organic solvents, the present invention has the great advantage of providing a guarantee for the safety of the use of heat-proof materials. The existing silicone rubber heat-proof coating can generally only be used in an environment of 3000kJ / kg and a working time of less than 500s, while the present invention can work in an application environment greater than 3000kJ / kg for more than 500s. Therefore, the material system used in the present invention also broadens the use environment of the silicone rubber heat-proof coating.

[0088] It should be pointed out that the purpose of comparative example 1 is only to illustrate that the present invention adopts the form of heat-proof film bonding to replace the spraying process in the existing technology, which has advantages in terms of curing time and green environmental protection. The coating formula used in the existing spraying process is not the same as the formula of the heat-proof film of the present invention. The formula system of the present invention is the result of special design for the form of heat-proof film.

[0089] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

[0090] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for preparing a rapid prototyping heat-resistant film, characterized in that: include: (1) uniformly dispersing the reinforcing filler and the ground fiber in the silicone rubber I to obtain a mixture A1; Silicone rubber I is a linear random copolymer of silazane and siloxane. The structural formula of silicone rubber I is as follows: Among them, x=3%~5% (x+y+z), y=5%~8% (x+y+z); The reinforcing filler is one or more combinations of carbon black, calcium carbonate and white carbon black; The mass ratio of silicone rubber I, reinforcing filler and ground fiber is 100:10-30:5-20; (2) vacuum kneading the mixture A1, the porcelain-forming filler, the curing agent I, the lightweight filler, the volatile viscosity reducer, and the curing inhibitor, taking a sample from the mixture obtained during the vacuum kneading process, heat-treating the sample, and determining whether the vacuum kneading is complete based on the mass change rate of the sample after the heat treatment. After the vacuum kneading is completed, a mixture A2 is obtained; The mass ratio of mixture A1, porcelain-forming filler, lightweight filler, volatile viscosity reducer, curing agent I and curing inhibitor is 100:30-50:15-30:2-15:0.4-1:0.2-0.5; In the volatile viscosity reducer, the mass ratio of monofluorodichloroethane to n-heptane is 100:0-3; The curing inhibitor is an alkynyl alcohol; (3) Spreading the mixture A2 between two layers of polytetrafluoroethylene films and calendering the mixture A2 to obtain a preliminary formed film; (4) curing the preliminarily formed film to obtain a heat-resistant film; In step (4), the specific method for curing the preliminary formed film is to heat and cure the preliminary formed film at a high temperature of 100 to 120° C. for 2 hours; The heat-resistant film is adhered to the surface of the metal substrate by an adhesive; the adhesive includes uniformly mixed silicone rubber II, tackifier and curing agent II, and the mass ratio of silicone rubber II, tackifier and curing agent II is 100:5-15:3-11; Silicone rubber II is epoxy modified vinyl silicone rubber with a molecular weight of 1×10 5 ~1.5×10 5 .

2. The method for preparing a rapid prototyping heat-resistant film according to claim 1, characterized in that: In step (1), the milled fiber is one or a combination of milled glass fiber and milled carbon fiber; The specific method for uniformly dispersing the reinforcing filler and the ground fiber in the silicone rubber is to grind with three rollers for 2 to 4 times or knead and disperse for 20 to 40 minutes to obtain a mixture A1 that is uniform in color and free of particles when observed with the naked eye.

3. The method for preparing a rapid prototyping heat-resistant film according to claim 1, characterized in that: In step (2): The porcelain-forming filler is one or more combinations of boron oxide, boron carbide and talc; Curing agent I is a platinum catalyst or chloroplatinic acid; The lightweight filler is one of glass microspheres and phenolic microspheres or a combination of the two; the isostatic strength of the glass microspheres and phenolic microspheres is greater than or equal to 2 MPa.

4. The method for preparing a rapid prototyping heat-resistant film according to claim 3, characterized in that: In step (2), the porcelain filler is a powder obtained by sieving through a 300-mesh vibrating sieve.

5. The method for preparing a rapid prototyping heat-resistant film according to claim 1, characterized in that: In step (2), vacuum kneading is carried out in a vertical kneader, the stirring paddle used for vacuum kneading is a frame type, and the vacuum degree of vacuum kneading is -0.01 MPa; After vacuum kneading for 15 to 30 minutes, a sample is taken out from the mixture obtained during the vacuum kneading process and the sample is heat-treated at 60°C for 15 minutes. When the mass change rate of the sample after heat treatment is less than 1%, the vacuum kneading is completed to obtain mixture A2.

6. The method for preparing a rapid prototyping heat-resistant film according to claim 1, characterized in that: In step (3), the thickness of the polytetrafluoroethylene film is 0.3 to 0.6 mm; In step (3), the mixture A2 is spread between two layers of polytetrafluoroethylene membranes. The specific method for calendering the mixture A2 is to set the gap between the calendering rollers of the parallel calender to 1 to 5 mm and repeat the calendering 1 to 3 times.

7. The method for preparing a rapid prototyping heat-resistant film according to claim 1, characterized in that: In step (3), the mixture A2 is first placed in a vacuum box and continuously subjected to vacuum negative pressure treatment at a vacuum degree of -0.01 to -0.03 MPa for 1 to 3 hours. The mixture A2 is then spread between two layers of polytetrafluoroethylene films and calendered to obtain a preliminary formed film.

8. A rapid prototyping heat-resistant film, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 7.

9. An application of a rapid prototyping heat-resistant film, characterized in that: include: Apply adhesive with a thickness of 200 to 400 μm on the surface of the metal substrate; Pressing the heat-resistant film obtained by the preparation method according to any one of claims 1 to 7 onto the adhesive scraped on the surface of the metal substrate, and squeezing out the remaining adhesive; After the metal substrate and the heat-proof film are wrapped with a plastic film, a vacuum pressure treatment is performed to obtain a heat-proof structural component.

10. The application of a rapid prototyping heat-resistant film according to claim 9, characterized in that: The tackifier is one or more combinations of white carbon black, red iron oxide and talc; The curing agent II is a mixture of chloroplatinic acid and hydrogen-containing silicone oil; the mass ratio of chloroplatinic acid to silicone rubber II is 0.3-0.5:100, and the mass ratio of hydrogen-containing silicone oil to silicone rubber II is 1:5-15.

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