Apparent adhesive film as well as preparation method and application thereof

Abstract

The invention discloses an apparent adhesive film as well as a preparation method and application thereof, and belongs to the technical field of composite materials. The apparent adhesive film comprises the following raw materials in parts by weight: 1400-1600 parts of epoxy resin, 200-300 parts of a room-temperature curing agent, 40-60 parts of a high-temperature curing agent, 20-50 parts of an accelerant, 10-40 parts of an auxiliary agent and 0-100 parts of color paste; the room-temperature curing agent is polyether amine; the high-temperature curing agent is dicyandiamide; and the accelerant is phenylurea propyl imidazole. The invention further discloses a preparation method and application of the apparent adhesive film. The apparent adhesive film provided by the invention effectively solves the problem of poor surface state of an oven cured product on the basis of not influencing the mechanical properties of the original system.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a surface adhesive film and a preparation method and application thereof. Background Art

[0002] The autoclave molding process is a relatively mature composite material molding process. It mainly uses the high-temperature compressed gas in the tank to generate pressure to pressurize and heat the composite blank to complete the curing molding. This process is widely used in the aerospace field; however, autoclave molding has the disadvantages of high process energy consumption, expensive equipment, low utilization rate, and high requirements for mold materials and processing, which makes its manufacturing cost high. With the increase in the use of composite materials in various fields and the increase in the size and complexity of composite materials, the field has put forward new demands for faster, more cost-effective and more versatile manufacturing methods, and the research and application of non-autoclave preparation processes have become increasingly in-depth and extensive.

[0003] The oven curing process is a process method for curing and molding prepregs in an oven. After conventional prepregs are cured in an oven, there are usually a large number of pinhole defects on the surface of the product, and the surface of the product needs to be further polished and painted to meet the appearance requirements. At present, the research on solving the defects of oven curing is mainly focused on the preparation of prepregs containing exhaust networks, such as using a two-step hot melt method to prepare prepregs, and micro-wetting the fibers by reducing the gram weight of the film on one side of the fibers to obtain incompletely impregnated fiber exhaust channels; or by introducing an intermediate layer that is not completely impregnated to obtain a prepreg containing an exhaust network; and the preparation process of such methods is complicated, and the degree of impregnation of the prepreg fibers is difficult to control and characterize, and products with special color requirements still need to be polished and sprayed, and still cannot improve the appearance of oven-cured products. Summary of the invention

[0004] The problem to be solved by the present invention is to provide a surface adhesive film and a preparation method and application thereof, which effectively solves the problem of poor surface state of oven-cured products without affecting the mechanical properties of the original system.

[0005] The technical solution adopted to solve the technical problem is to provide an apparent adhesive film, comprising the following raw materials in parts by weight: 1400-1600 parts of epoxy resin, 200-300 parts of room temperature curing agent, 40-60 parts of high temperature curing agent, 20-50 parts of accelerator, 10-40 parts of auxiliary agent and 0-100 parts of color paste; The room temperature curing agent is polyetheramine; the high temperature curing agent is dicyandiamide; and the accelerator is phenylurea propyl imidazole.

[0006] The beneficial effects of the above technical scheme of the present invention are as follows: the polyetheramine in the present invention is used as a room temperature curing agent, which has a lower curing temperature and can start to react at room temperature or a lower temperature, so that the composition maintains a lower viscosity before coating, which is convenient for mixing operations, while dicyandiamide is used as a high temperature curing agent and needs to react at a higher temperature; after coating, the polyetheramine reacts through heat treatment, which increases the viscosity of the system and reaches a preset viscosity state, which can save energy and improve production efficiency. At the same time, by controlling the ratio of the room temperature curing agent to the high temperature curing agent, the viscosity of the apparent film is controlled at a higher level, and better positioning can be achieved during the curing process combined with the product, and the excellent exhaust performance of the film itself can be used to solve the pinhole defects on the surface of the oven-cured product without introducing an additional exhaust channel; the apparent film of the present invention has no special requirements for production equipment, and does not need to change the original curing system of the product. Its excellent appearance state can cancel the post-processing process such as grinding of the cured product, and further adding color paste to the apparent film can obtain a product that does not need to be polished or sprayed, which significantly improves production efficiency and reduces costs. At the same time, the introduction of the surface film does not affect the original mechanical properties of the system and can be widely used in defect treatment and improvement of product surfaces.

[0007] In addition, the use of phenylurea propyl imidazole as an accelerator can reduce the reaction temperature of dicyandiamide while ensuring that the system has good low-temperature latency, ensuring that the curing processes of polyetheramine and dicyandiamide are independent of each other and do not interfere with each other; phenylurea propyl imidazole can also achieve the curing of the adhesive film within a wider temperature range, which makes the adhesive film more widely used in combination with materials such as prepregs and can adapt to more different application scenarios and process requirements.

[0008] Preferably, the surface adhesive film comprises the following raw materials in parts by weight: 1499-1501 parts of epoxy resin, 238-300 parts of room temperature curing agent, 44-60 parts of high temperature curing agent, 25-41 parts of accelerator, 20-30 parts of auxiliary agent and 75-91 parts of color paste.

[0009] More preferably, the surface adhesive film includes the following raw materials in parts by weight: 1500.3 parts of epoxy resin, 239.9 parts of room temperature curing agent, 58.9 parts of high temperature curing agent, 40.3 parts of accelerator, 30 parts of auxiliary agent and 75.2 parts of color paste.

[0010] Preferably, phenylurea propyl imidazole is prepared by the following steps: Dissolve 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in a solvent, and stir the mixture at 25-30° C. for 22-24 hours to obtain the product.

[0011] More preferably, phenylurea propyl imidazole is prepared by the following steps: Dissolve 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in a solvent, and stir the mixture at 30° C. for 24 hours to obtain the product.

[0012] Preferably, the epoxy resin is prepared by the following steps: The hydantoin epoxy resin and the hydrogenated bisphenol A modified epoxy resin are baked at 70-90°C for 25-30 minutes respectively, and then mixed and stirred for 10-20 minutes to obtain the product.

[0013] The beneficial effects of the technical scheme adopted in the present invention are as follows: the present invention adopts hydantoin epoxy resin and hydrogenated bisphenol A modified epoxy resin as raw materials of epoxy resin, which can significantly improve the weather resistance of the apparent film; hydantoin epoxy resin usually has good UV resistance and weather resistance due to its special chemical structure; hydrogenated bisphenol A modified epoxy resin reduces unsaturated bonds through hydrogenation reaction, thereby improving weather resistance and antioxidant properties; the use of the two resins in combination can further enhance the weather resistance of the film, making it less likely to turn yellow or powdery under sunlight or ultraviolet radiation, thereby better protecting the product and extending its service life.

[0014] More preferably, the epoxy resin is prepared by the following steps: The hydantoin epoxy resin and the hydrogenated bisphenol A modified epoxy resin are baked at 80° C. for 30 minutes respectively, and then mixed and stirred for 20 minutes to obtain the hydantoin epoxy resin; the weight ratio of the hydantoin epoxy resin to the hydrogenated bisphenol A modified epoxy resin is 6-8:2-4.

[0015] More preferably, the weight ratio of the hydantoin epoxy resin to the hydrogenated bisphenol A modified epoxy resin is 7:3.

[0016] Preferably, the auxiliary agent is fumed silica.

[0017] The present invention also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding a high temperature curing agent and an accelerator to an epoxy resin in sequence, and stirring in a vacuum to obtain a first mixture; (2) adding a room temperature curing agent, an auxiliary agent and a color paste to the first mixture in sequence, and stirring in a vacuum to obtain a second mixture; (3) The second mixture is subjected to film coating, heat treatment of film lamination and hot pressing rollers and then rolled up to obtain an apparent adhesive film.

[0018] The beneficial effect of the technical solution adopted in the present invention is as follows: a hot pressing roller treatment process is added during the preparation of the film, so that the film can be used directly after being rolled up, without the need for a aging process after rolling up; this is mainly because the heat treatment accelerates the curing reaction of the polyetheramine, so that the film has the required state when it is rolled up, which can simplify the production process and significantly improve production efficiency.

[0019] Preferably, the temperature of the epoxy resin in step (1) is 45-55° C.; the temperature of the vacuum stirring in step (1) is 45-55° C., and the time is 20-30 min.

[0020] More preferably, the temperature of the epoxy resin in step (1) is 50° C.; the temperature of the vacuum stirring in step (1) is 50° C. and the time is 25 min.

[0021] Preferably, the temperature of the first mixture in step (2) is 25-35° C.; the temperature of the vacuum stirring in step (2) is 25-35° C., and the time is 50-60 min.

[0022] More preferably, the temperature of the first mixture in step (2) is 30° C.; the temperature of the vacuum stirring in step (2) is 30° C. and the time is 50 min.

[0023] Preferably, in step (3), the speeds of coating, laminating heat treatment and hot pressing roller are all 1.5~2.5m / min; the coating temperature is 20~30°C; the laminating heat treatment is respectively carried out in heat treatment sections of 35~45°C and 55~65°C, and the treatment time is 2~5min; the temperature of the hot pressing roller is 25~35°C, and the pressure is 0.08~0.15MPa.

[0024] More preferably, in step (3), the speeds of coating, laminating heat treatment and hot pressing roller are all 2m / min; the coating temperature is 25°C; the laminating heat treatment is respectively carried out in heat treatment sections of 40°C and 60°C, and the treatment time is 5min; the temperature of the hot pressing roller is 30°C and the pressure is 0.08MPa.

[0025] The present invention also provides the use of the above-mentioned surface adhesive film in preparing laminated boards by oven curing.

[0026] The present invention has the following beneficial effects: (1) The present invention adopts a combination of hyaluronic acid epoxy resin and hydrogenated bisphenol A modified epoxy resin to increase the weather resistance of the surface film. After being combined with the product, it is not easy to turn yellow or powder under sunlight or ultraviolet radiation, which can play a better protective role and extend the service life of the product.

[0027] (2) The present invention uses two curing agents with different reactivity in combination, which can keep the composition at a low viscosity before coating, making the mixing operation convenient. After coating, it is subjected to heat treatment to promote the reaction of the low-temperature curing agent, increase the viscosity, and reach a preset viscous state, thereby saving energy consumption. In addition, a heat treatment process is added during the preparation of the film, so that the film can be used directly after winding, eliminating the aging process after winding, thereby improving production efficiency.

[0028] (3) The present invention utilizes phenylurea propyl imidazole as an accelerator, which reduces the reaction temperature of dicyandiamide while ensuring that the system has good low-temperature latency, ensuring that the curing process of the polyetheramine and the curing process of dicyandiamide are independent of each other. At the same time, phenylurea propyl imidazole can achieve curing of the adhesive film within a wider temperature range, and has a wider range of applications when used in combination with prepregs.

[0029] (4) The present invention controls the initial viscosity of the surface film at a relatively high level by controlling the ratio of the room temperature curing agent to the high temperature curing agent. During the curing process combined with the product, better positioning can be achieved. In addition, the excellent exhaust properties of the film itself can be utilized to solve the surface pinhole defects of the oven-cured product without introducing additional exhaust channels. The prepared surface film has no special requirements for the production equipment and does not require changing the original curing system of the product. The excellent appearance state can eliminate post-processing steps such as polishing. Further, by adding color paste to the surface film, a product that does not require polishing or painting can be obtained, which significantly improves production efficiency and reduces costs. In addition, the introduction of the surface film does not affect the original mechanical properties of the system and can be widely used to improve defects on the surface of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a physical picture of the appearance of the laminated board combined with the surface adhesive film and the prepreg in Example 1; Figure 2 This is a physical picture of the appearance of the laminated board combined with the surface adhesive film and the prepreg in Example 2; Figure 3 This is a physical picture of the appearance of the laminated board combined with the surface adhesive film and the prepreg in Example 3; Figure 4 This is a physical picture of the appearance of the laminated board combined with the surface adhesive film and the prepreg in Comparative Example 1; Figure 5 This is a physical picture of the appearance of the laminated board combined with the surface adhesive film and the prepreg in Comparative Example 2; Figure 6 This is a physical picture of the appearance of a laminate containing only prepreg. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0032] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0033] The features and performance of the present invention are further described in detail below in conjunction with embodiments.

[0034] Example 1 An apparent adhesive film comprises the following raw materials in parts by weight: 1500.3 parts of epoxy resin, 239.9 parts of polyetheramine, 58.9 parts of dicyandiamide, 40.3 parts of phenylurea propyl imidazole, 30 parts of fumed silica and 75.2 parts of color paste; The epoxy resin is prepared by the following steps: 1050.1 parts by weight of hydantoin epoxy resin and 450.2 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 80° C. for 30 minutes and then mixed and stirred for 20 minutes to obtain the epoxy resin; Among them, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, stirring and reacting at 25° C. for 24 hours to obtain the product.

[0035] This embodiment also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 50° C. in sequence, and stirring under vacuum at 50° C. for 25 minutes to obtain a first mixture; (2) cooling the first mixture to 30° C., adding polyetheramine, fumed silica and color paste in sequence, and stirring under vacuum at 30° C. for 50 min to obtain a second mixture; (3) The production speed is set to 2 m / min, the coating machine temperature is set to 25°C, the second mixture is poured into the glue tank for coating, and after coating, a first heat treatment at 40°C for 5 min and a second heat treatment at 60°C for 5 min are performed in sequence, and then the mixture is rolled up after being subjected to a hot pressing roller at 30°C and 0.08 MPa to obtain an apparent glue film.

[0036] Example 2 An apparent adhesive film comprises the following raw materials in parts by weight: 1499.7 parts of epoxy resin, 265.1 parts of polyetheramine, 50.2 parts of dicyandiamide, 33.1 parts of phenylurea propyl imidazole, 25.5 parts of fumed silica and 90.2 parts of color paste; The epoxy resin is prepared by the following steps: 1050 parts by weight of hydantoin epoxy resin and 449.7 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 80° C. for 30 minutes and then mixed and stirred for 20 minutes to obtain the epoxy resin; Among them, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, stirring and reacting at 25° C. for 24 hours to obtain the product.

[0037] This embodiment also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 50° C. in sequence, and stirring under vacuum at 50° C. for 25 minutes to obtain a first mixture; (2) cooling the first mixture to 30° C., adding polyetheramine, fumed silica and color paste in sequence, and stirring under vacuum at 30° C. for 50 min to obtain a second mixture; (3) The production speed is set to 2 m / min, the coating machine temperature is set to 25°C, the second mixture is poured into the glue tank for coating, and after coating, a first heat treatment at 40°C for 5 min and a second heat treatment at 60°C for 5 min are performed in sequence, and then the mixture is rolled up after being subjected to a hot pressing roller at 30°C and 0.08 MPa to obtain an apparent glue film.

[0038] Example 3 An apparent adhesive film comprises the following raw materials in parts by weight: 1499.9 parts of epoxy resin, 299.8 parts of polyetheramine, 44.8 parts of dicyandiamide, 27 parts of phenylurea propyl imidazole, 20.3 parts of fumed silica and 89.8 parts of color paste; The epoxy resin is prepared by the following steps: 1049.9 parts by weight of hydantoin epoxy resin and 450 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 80° C. for 30 minutes and then mixed and stirred for 15 minutes to obtain the epoxy resin; Wherein, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, and stirring the mixture at 25° C. for 24 hours to obtain the product.

[0039] This embodiment also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 50° C. in sequence, and stirring under vacuum at 50° C. for 25 minutes to obtain a first mixture; (2) cooling the first mixture to 30° C., adding polyetheramine, fumed silica and color paste in sequence, and stirring under vacuum at 30° C. for 50 min to obtain a second mixture; (3) The production speed is set to 2 m / min, the coating machine temperature is set to 25°C, the second mixture is poured into the glue tank for coating, and after coating, a first heat treatment at 40°C for 5 min and a second heat treatment at 60°C for 5 min are performed in sequence, and then the mixture is rolled up after being subjected to a hot pressing roller at 30°C and 0.15 MPa to obtain an apparent glue film.

[0040] Example 4 A surface adhesive film comprises the following raw materials in parts by weight: 1400 parts of epoxy resin, 200 parts of polyetheramine, 40 parts of dicyandiamide, 20 parts of phenylurea propyl imidazole and 10 parts of fumed silica; The epoxy resin is prepared by the following steps: 840 parts by weight of hydantoin epoxy resin and 560 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 70° C. for 30 minutes and then mixed and stirred for 20 minutes to obtain the epoxy resin; Wherein, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, and stirring the mixture at 25° C. for 22 hours to obtain the product.

[0041] This embodiment also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 45° C. in sequence, and stirring under vacuum at 45° C. for 20 minutes to obtain a first mixture; (2) cooling the first mixture to 25° C., adding polyetheramine and fumed silica in sequence, and stirring under vacuum at 25° C. for 60 min to obtain a second mixture; (3) The production speed is set to 1.5 m / min, the coating machine temperature is set to 20°C, the second mixture is poured into the glue tank for coating, and after coating, the first stage heat treatment at 35°C for 5 min and the second stage heat treatment at 55°C for 5 min are sequentially performed, and then the mixture is rolled up after being subjected to a hot pressing roller at 25°C and 0.08 MPa to obtain an apparent glue film.

[0042] Example 5 A surface adhesive film comprises the following raw materials in parts by weight: 1600 parts of epoxy resin, 300 parts of polyetheramine, 60 parts of dicyandiamide, 50 parts of phenylurea propyl imidazole, 40 parts of fumed silica and 100 parts of color paste; The epoxy resin is prepared by the following steps: 1280 parts by weight of hydantoin epoxy resin and 320 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 90° C. for 25 minutes and then mixed and stirred for 10 minutes to obtain the epoxy resin; Among them, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, stirring and reacting at 30° C. for 24 hours to obtain the product.

[0043] This embodiment also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 55° C. in sequence, and stirring under vacuum at 55° C. for 30 minutes to obtain a first mixture; (2) cooling the first mixture to 35° C., adding polyetheramine, fumed silica and color paste in sequence, and stirring under vacuum at 35° C. for 50 min to obtain a second mixture; (3) The production speed was set to 2.5 m / min, the coating machine temperature was set to 30°C, the second mixture was poured into the glue tank for coating, and after coating, a first heat treatment at 45°C for 2 min and a second heat treatment at 65°C for 2 min were performed in sequence, and then the mixture was rolled up after being subjected to a hot pressing roller at 35°C and 0.15 MPa to obtain an apparent glue film.

[0044] Comparative Example 1 An apparent adhesive film comprises the following raw materials in parts by weight: 1499.8 parts of epoxy resin, 240.1 parts of polyetheramine, 59 parts of dicyandiamide, 40.1 parts of phenylurea propyl imidazole and 75 parts of color paste; The epoxy resin is prepared by the following steps: 1049.8 parts by weight of hydantoin epoxy resin and 450 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 80° C. for 30 minutes and then mixed and stirred for 20 minutes to obtain the epoxy resin; Wherein, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, and stirring the mixture at 25° C. for 24 hours to obtain the product.

[0045] This comparative example also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide and phenylureapropyl imidazole to an epoxy resin at 50° C. in sequence, and stirring under vacuum at 50° C. for 25 minutes to obtain a first mixture; (2) cooling the first mixture to 30° C., adding polyetheramine and color paste in sequence, and stirring under vacuum at 30° C. for 55 min to obtain a second mixture; (3) The production speed is set to 2 m / min, the coating machine temperature is set to 25°C, the second mixture is poured into the glue tank for coating, and after coating, a first heat treatment at 40°C for 5 min and a second heat treatment at 60°C for 5 min are performed in sequence, and then the mixture is rolled up after being subjected to a hot pressing roller at 30°C and 0.08 MPa to obtain an apparent glue film.

[0046] Comparative Example 2 A surface adhesive film comprises the following raw materials in parts by weight: 1500 parts of epoxy resin, 45 parts of dicyandiamide, 26.9 parts of phenylurea propyl imidazole, 30.2 parts of fumed silica and 75 parts of color paste; The epoxy resin is prepared by the following steps: 1050 parts by weight of hydantoin epoxy resin and 450 parts by weight of hydrogenated bisphenol A modified epoxy resin are respectively baked at 80° C. for 30 minutes and then mixed and stirred for 20 minutes to obtain the epoxy resin; Wherein, phenylureapropyl imidazole is prepared by the following steps: dissolving 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in dichloromethane, and stirring the mixture at 25° C. for 24 hours to obtain the product.

[0047] This comparative example also provides a method for preparing the above-mentioned surface adhesive film, comprising the following steps: (1) adding dicyandiamide, phenylurea propyl imidazole, fumed silica and color paste to an epoxy resin at 50° C. in sequence, and stirring under vacuum at 50° C. for 25 minutes to obtain a first mixture; (2) The production speed is set to 2 m / min, the coating machine temperature is set to 25°C, the second mixture is poured into the glue tank for coating, and after coating, a first heat treatment at 40°C for 5 min and a second heat treatment at 60°C for 5 min are performed in sequence, and then the mixture is rolled up after being subjected to a hot pressing roller at 30°C and 0.15 MPa to obtain an apparent glue film.

[0048] Experimental example 1. Mechanical properties test The surface adhesive films prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were combined with the prepreg EG / 61233 / 209Ba, and the operations were specifically performed according to the following steps: (1) Mold preparation: Use a flat glass mold and apply the release agent evenly on the mold surface 3 times every 15 minutes; (2) Laying: First, lay the surface adhesive film on the mold, pre-evacuate for 15 minutes under the condition of vacuum not less than 0.085MPa, then lay the required number of layers of prepreg EG / 61233 / 209Ba according to the test standard in Table 1 below, pre-evacuate for 15 minutes after laying 5 layers, and place the porous isolation film, release cloth, equalizing plate and breathable adhesive in order after the laying, and add exhaust channels around the laminate, then pack it with a vacuum bag, and pre-evacuate for 60 minutes under the condition of vacuum not less than 0.085MPa; (3) Curing: Curing is carried out according to the system of 80℃ / 60min+130℃ / 120min, and demoulding is carried out after cooling to room temperature.

[0049] In addition, the laminate obtained by only using EG / 61233 / 209Ba ply was used as the control group. The prepreg EG / 61233 / 209Ba used in the experiment was from Chengdu Luchen New Material Technology Co., Ltd. The test standards and mechanical results are shown in Table 1.

[0050] Table 1 Mechanical properties results

[0051] It can be seen from the mechanical test results in Table 1 that the mechanical properties of the laminate do not change significantly after the surface adhesive film prepared by the present invention is introduced, and the minimum mechanical property loss rate is 2.6%, indicating that the introduction of the surface adhesive film will not cause changes in the mechanical properties of the prepreg.

[0052] 2. Appearance test The examples 1 to 3 and the comparative examples 1 to 2 were combined with the prepreg EG / 61233 / 209Ba, respectively, and the appearance was observed after curing in an oven. The results are as follows: Figures 1 to 6 shown.

[0053] like Figures 1 to 6 It can be seen that the surface of the laminate obtained by the apparent films of Examples 1 to 3 is smooth and defect-free. The surface of the laminate prepared by the apparent film of Comparative Example 1 has irregularly distributed defects. This is because the lack of fumed silica causes slight shrinkage holes to appear in the heat treatment section. During the curing process, the air is enclosed in the cavities, and finally defects are formed on the surface, indicating that the introduction of fumed silica is beneficial to improve the film-forming properties and prevent shrinkage holes from appearing during the heat treatment process to obtain a uniform film. The surface of the laminate prepared by the apparent film of Comparative Example 2 has more pore defects. This is because the lack of room temperature curing agent causes the film to be sticky, and the air discharge between the film and the mold surface is not smooth, which leads to obvious defects.

[0054] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any form. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the scope of the present invention.

Claims

1. A surface film, characterized in that: The invention comprises the following raw materials in parts by weight: 1400-1600 parts of epoxy resin, 200-300 parts of room temperature curing agent, 40-60 parts of high temperature curing agent, 20-50 parts of accelerator, 10-40 parts of auxiliary agent and 0-100 parts of color paste; The room temperature curing agent is polyetheramine; the high temperature curing agent is dicyandiamide; and the accelerator is phenylurea propyl imidazole.

2. The surface adhesive film according to claim 1, characterized in that: The method comprises the following raw materials in parts by weight: 1499-1501 parts of epoxy resin, 238-300 parts of room temperature curing agent, 44-60 parts of high temperature curing agent, 25-41 parts of accelerator, 20-30 parts of auxiliary agent and 75-91 parts of color paste.

3. The surface adhesive film according to claim 1 or 2, characterized in that: The phenylurea propyl imidazole is prepared by the following steps: Dissolve 1-(3-aminopropyl)imidazole and phenyl isocyanate in an equal molar ratio in a solvent, and stir the mixture at 25-30° C. for 22-24 hours to obtain the product.

4. The surface adhesive film according to claim 1 or 2, characterized in that: The epoxy resin is prepared by the following steps: The hydantoin epoxy resin and the hydrogenated bisphenol A modified epoxy resin are baked at 70-90° C. for 25-30 minutes respectively, and then mixed and stirred for 10-20 minutes to obtain the hydantoin epoxy resin; the weight ratio of the hydantoin epoxy resin to the hydrogenated bisphenol A modified epoxy resin is 6-8:2-4.

5. The surface adhesive film according to claim 1 or 2, characterized in that: The auxiliary agent is fumed silica.

6. The method for preparing the surface adhesive film according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) adding a high temperature curing agent and an accelerator to an epoxy resin in sequence, and stirring in a vacuum to obtain a first mixture; (2) adding a room temperature curing agent, an auxiliary agent and a color paste to the first mixture in sequence, and stirring in a vacuum to obtain a second mixture; (3) The second mixture is subjected to film coating, heat treatment of film lamination and hot pressing rollers and then rolled up to obtain an apparent adhesive film.

7. The method for preparing the surface adhesive film according to claim 6, characterized in that: The temperature of the epoxy resin in step (1) is 45-55° C.; the temperature of the vacuum stirring in step (1) is 45-55° C. and the time is 20-30 min.

8. The method for preparing the surface adhesive film according to claim 6, characterized in that: The temperature of the first mixture in step (2) is 25-35° C.; the temperature of the vacuum stirring in step (2) is 25-35° C. and the time is 50-60 min.

9. The method for preparing the surface adhesive film according to claim 6, characterized in that: In the step (3), the speeds of the coating, laminating heat treatment and hot pressing roller are all 1.5-2.5 m / min; the coating temperature is 20-30°C; the laminating heat treatment is respectively carried out in heat treatment sections of 35-45°C and 55-65°C, and the treatment time is 2-5 min; the temperature of the hot pressing roller is 25-35°C, and the pressure is 0.08-0.15 MPa.

10. Use of the surface adhesive film according to any one of claims 1 to 5 in preparing laminated boards by oven curing.

Images