Composite film and use thereof

Abstract

This invention proposes a composite film comprising a fiber layer and a first resin layer, with a stiffness of 2.0-9.9 cm, exhibiting moderate stiffness and ease of installation. By combining the composite film with the fiber layer, the functionality of the resin layer is retained while improving the overall usability of the composite film. This composite film can be used in fields such as heat transfer printing, particularly in vacuum forming, where the functional layer can be directly transferred to the surface of the molded product. This eliminates the high dust and VOC emissions associated with existing methods, achieving the beneficial effects of high-efficiency production, high dimensional accuracy, low resin surface pollution, and an environmentally friendly production process.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and relates to a composite film containing a fiber layer and having moderate stiffness. Background Technology

[0002] Fibers are substances composed of continuous or discontinuous filaments. Fibers include natural fibers and chemical fibers, among which chemical fibers are produced through chemical processing and can be divided into man-made fibers (regenerated fibers), synthetic fibers, and inorganic fibers. Fibers can be woven into fine threads, yarns, and ropes; in papermaking or felt weaving, they can also be woven into fiber layers. They are also frequently used to manufacture other materials and to form composite materials with other materials, finding wide application in textiles, military, construction, environmental protection, and medicine. Improving the properties of existing materials using fibers or fiber products is a major research and application focus.

[0003] Thin films refer to thin layers of metal or organic materials with a thickness ranging from a single atom to several millimeters. Single-material or single-layer thin film materials have increasingly limited applications due to their performance limitations. Composite films, on the other hand, are polymer materials composed of two or more layers of films made of different materials. Through composite processing, materials with superior comprehensive properties exceeding those of any single material can be obtained. The composite of resin films and fibers typically takes two forms. One is to directly mix the fibers into the resin to obtain a composite material with fibers dispersed internally; the other is to directly bond the fiber layer to the resin layer, with partial or no blending between the two layers during bonding. How to improve the performance of resin films and thus broaden their application areas through composite processing has always been a hot topic of research.

[0004] Patent document 1 (CN106827580A) discloses a method of laminating carbon fiber cloth and glass fiber cloth by soaking them in a thermosetting resin solution for an extended period of time and then heating and pressurizing them together. Although this method shortens the processing time and improves the yield, it has problems such as cumbersome processing and thicker finished products. Furthermore, the composite materials prepared by this method do not have flexibility and cannot be used as thin film materials.

[0005] Patent document 2 (CN104441835B) discloses a heat-radiation-resistant, waterproof, and breathable membrane and its preparation method. A multifunctional composite film is obtained by integrating a fiberglass cloth layer, a thermoplastic polyurethane layer, and a perforated aluminum foil layer through heat sealing. However, this system simply superimposes the functions of each layer. Due to factors such as unreasonable performance parameters of the fiberglass cloth layer, the film's flexibility or stiffness is poor. It is speculated that when used in the construction field as a waterproof and breathable cushion layer for pitched roofs and an internal thermal insulation and protective layer for building curtain walls, it will face problems such as low efficiency in large-area installation.

[0006] Patent document 3 (CN209908843U) discloses a composite wind turbine blade made by stacking multiple layers of carbon fiber cloth and multiple layers of expanded material. This blade has excellent properties such as high stiffness, light weight, good toughness, and impact resistance. However, the overall thickness of this structure has certain requirements, and the resulting materials do not have flexibility and cannot be used as thin film materials.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: CN106827580A

[0010] Patent Document 2: CN104441835B

[0011] Patent Document 3: CN209908843U Summary of the Invention

[0012] To address the aforementioned problems, this invention proposes a composite film containing a glass layer and possessing moderate stiffness. This composite film is easy to lay and has a good appearance when used. Furthermore, it can be transferred onto molded parts during use, thereby giving the molded parts a good appearance and functionality.

[0013] The purpose of this invention is to provide a composite film. This composite film contains a first resin layer and a fiber layer, and the stiffness of the composite film is 2.0-9.9 cm. "Stiffness" refers to the degree of sagging that occurs when a film of a specific size is suspended for 10 cm, due to differences in the film's own rigidity. Figure 1 Stiffness can then be tested and calculated. The stiffness value ranges from 0 to 10 cm. The higher the stiffness, the higher the rigidity of the film and the less noticeable the sag.

[0014] The composite film of this invention can be used for laying on large-area molds, especially curved mold surfaces. During laying, if the stiffness is too low, wrinkles are easily generated; if the stiffness is too high, it is difficult to adhere to mold surfaces with large curvature variations. To enable the composite film to have a higher laying speed and good adhesion to complex mold surfaces, it is further preferred that the stiffness of the composite film be 3.0-8.5 cm.

[0015] The fiber layer in a composite film is an effective means of improving the stiffness of the resin layer. The fiber layer can refer to one or more layers of film-like fiber products stacked together, and the structures of each layer can be the same or different. Unless otherwise specified, the fiber layer described in this invention is an integral fiber layer consisting of one or more layers of film-like fiber products stacked together.

[0016] The fiber layer thickness of the composite film can be 0.01-20 mm. When the thickness is within the above range, the adhesion between the composite film and the mold can be ensured while adjusting the stiffness of the resin layer. To obtain high layability, the fiber layer thickness of the composite film is preferably 0.1-2.0 mm. Considering the better applicability of the composite film, 0.15-1.5 mm is preferred. More preferably, it is a combination of two fiber layers of different thicknesses, such as a combination of a thin layer of 0.15-0.5 mm and a thick layer of 0.5-1.0 mm. When the fiber layer is a multi-layer film-like fiber product, the fiber layer thickness is the sum of the thicknesses of the entire fiber layer.

[0017] The areal density of the fiber layer in the composite film can be 10-3500 g / m³. 2 To ensure the fiber layer itself possesses a certain degree of stiffness, the areal density of the fiber layer in the composite film is preferably 20-2500 g / m³. 2 Considering that using excessively high areal density would lead to excessively high costs, the areal density of the fiber layer is further preferably 20-1600 g / m². 2 A more preferred embodiment is a combination of two fiber layers with different areal densities, such as a low areal density layer of 20-30 g / m². 2 and high areal density layers 800-1500g / m 2 The combination of [various elements]. When the fiber layer is a multi-layered thin-film fiber product, the surface density of the fiber layer is the sum of the surface densities of the entire fiber layer.

[0018] The surface roughness of the fiber layer in a composite film also affects its performance. Generally, when the fiber layer is a single thin-film fiber product, its upper and lower surfaces are considered to have the same surface roughness. When the fibers are multiple layers of stacked thin-film fiber products, the surface roughness of the upper and lower surfaces can be the same or different. In this case, the surface roughness specifically refers to the surface roughness of the surface adjacent to the first resin layer. Generally, the surface roughness of the fiber layer can range from 0.1 to 500 μm. To prevent the fiber layer texture from being imprinted into the first resin layer during use, thus avoiding poor appearance, and considering the process requirements and cost of preparing the corresponding fiber layer, the surface roughness of the fiber layer is preferably 0.5 to 100 μm. To further improve the appearance of the first resin layer and avoid the influence of fiber layer texture, the surface roughness of the fiber layer can be further preferably 0.5 to 10 μm. Considering that woven fiber layers typically have high surface roughness but wide applications, a combination of two different surface roughness fiber layers—a low surface roughness layer of 0.5-2.5 μm and a high surface roughness layer of 2.5-10 μm—is preferred, with the low surface roughness layer adjacent to the resin layer. When the fiber layer is a multilayer film-like fiber product, the surface roughness of the fiber layer must be specified as the surface roughness corresponding to the upper or lower surface of the overall fiber layer.

[0019] The fiber layer described in this invention can be a pure fiber layer formed by needle punching, papermaking, or spinning after fiber layup, or it can contain other components introduced by methods such as soaking, spraying, or melt blending. The fibers can also be natural or synthetic fibers. Preferably, the fiber layer contains 85 parts by weight or more of glass fiber and / or carbon fiber per 100 parts by weight. Considering higher strength and better cost, it is further preferred to contain 90-98 parts by weight of glass fiber and / or carbon fiber.

[0020] The first resin layer and the fiber layer in this invention can be laminated using various methods, such as coating and hot pressing. Considering the tight adhesion between the layers, resistance to delamination, good appearance, and good overall layability of the composite film, while maintaining the good appearance of the resin layer, the peel strength between the first resin layer and the fiber layer can be 0.01–200 N / cm. To avoid damaging the structure of each layer during lamination and to prevent delamination during use, the peel strength between the first resin layer and the fiber layer is preferably 0.01–20 N / cm. When the fiber layer does not penetrate the first resin layer, it helps prevent defects such as fiber lines from appearing on the molded product; therefore, the peel strength between the first resin layer and the fiber layer is preferably 0.01–1 N / cm. For better applicability of the composite film, a further preferred value is 0.05–0.5 N / cm.

[0021] The first resin layer is a functional layer of the composite film. Examples of these functionalities include heat resistance, light resistance, UV resistance, flame retardancy, corrosion resistance, solvent resistance, water resistance, aging resistance, fuel oil resistance, hydraulic oil resistance, abrasion resistance, impact resistance, and decorative properties. Considering the functionality of the first resin layer, it is preferable to contain one or more of polyurethane resin, epoxy resin, unsaturated polyester resin, acrylic resin, or fluororesin.

[0022] Specifically, the first resin layer may contain one or more of polyurethane resin, epoxy resin, unsaturated polyester resin, acrylic resin, or fluororesin.

[0023] The aforementioned polyurethane resin refers to a polymer compound with urethane groups on its main chain. Polyurethane resins are typically produced by reacting polyols with isocyanates. Examples of polyols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, dihydroxypolypropylene oxide, trihydroxypolypropylene oxide, tetrahydroxypropylethylenediamine, or dihydroxypolytetrahydrofuran propylene oxide, all containing multiple hydroxyl groups. Examples of isocyanates include toluene diisocyanate, phenyl diisocyanate, methylene diphenyl diisocyanate, phenyl diisocyanate, naphthalene diisocyanate, benzyl diisocyanate, bitoluidine diisocyanate, or α,α,α',α'-tetramethylphenyl diisocyanate, as well as aromatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl diisocyanate. These substances can be used alone or in combination. For example, the following are examples of cured polymers or coatings: Jotun Paints (Zhangjiagang) Co., Ltd.'s BC100A / B series; Shanghai Mega Paints Co., Ltd.'s WU210A / B series and WU233A / B series; Pompeii Paints (Shanghai) Co., Ltd.'s LT2552 / LW7260 series; Junhe Chemical (Shanghai) Co., Ltd.'s JH-8152 / 3390 series; and Hongze Tiancheng Science and Trade Co., Ltd.'s 881-FYDM-A / B series.

[0024] The epoxy resins mentioned above refer to polymers containing two or more epoxy groups in their molecules. Examples of such polymers or cured coatings include: LP149 series from Pompeii Paints (Shanghai) Co., Ltd.; 670HS-A / B series from AkzoNobel; and EM400-A / B series from Double Lion Paints Co., Ltd.

[0025] The aforementioned unsaturated polyester resins are polymers whose molecular structure contains ester bonds and unsaturated bonds. Examples of such polymers or cured coatings include: the 191 series produced by Sanhua Chemical Coatings Co., Ltd.; and the TS-817 series produced by Qingyi Chemical Materials Co., Ltd.

[0026] The aforementioned acrylic resin is a copolymer synthesized primarily from vinyl monomers such as acrylates, methacrylates, and styrene. Examples of the monomers include methyl methacrylate, ethyl methacrylate, styrene, acrylonitrile, ethyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, n-octyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, acrylamide, N-hydroxymethylacrylamide, N-butoxymethyl(methyl)acrylamide, diacetone acrylamide, ethyl acetoacetate methacrylate, divinylbenzene, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloyloxypropyltrimethoxysilane, styrene sulfonic acid, sodium vinyl sulfonate, etc., or copolymers of the above chemical structures with other chemical structures. For example, the following are examples of cured polymers or coatings: FNUH-606 series produced by Renai Technology Development Co., Ltd.; E0512 series produced by Yoshida Chemical Co., Ltd.

[0027] The aforementioned fluororesins refer to polymers containing fluorine atoms in their molecular structure. Examples include perfluorinated alkyl vinyl ether copolymers, perfluorinated isopropylene, ethylene-tetrafluoroethylene copolymers, polyvinylidene fluoride, polychlorotrifluoroethylene, and copolymers of the above chemical structures with other chemical structures. For example, cured polymers or coatings such as the YQ-F-011-Ⅰ series produced by Shandong Yingqiang New Material Technology Co., Ltd., and the HC-0210F-A / B series produced by Renai Technology Development Co., Ltd. can be listed.

[0028] Furthermore, considering the availability and cost of resins in fiber composites, the first resin layer preferably contains one or more of thermosetting polyurethane resin, thermosetting epoxy resin, and thermosetting acrylic resin.

[0029] Crosslinking degree is a quantitative parameter of the crosslinking structure in the resin. It affects the strength and stiffness of the first resin layer, as well as the interlayer interaction when composited with the fiber layer, further influencing the stiffness of the composite film. The crosslinking degree of the first resin layer can be 0-100%. To further ensure the strength of the functional layer, the crosslinking degree of the first resin layer is preferably 20-100%. To ensure that the first resin layer retains some reactive groups, the crosslinking degree is further preferably 40-85%.

[0030] The thickness of the first resin layer can be 50-500μm, and considering functional requirements and cost, it is more preferably 90-300μm.

[0031] The stiffness of the first resin layer, which is in the form of a thin film, can be 0-7 cm. The stiffness of the first resin layer can be partially adjusted by changing its thickness.

[0032] Preferably, a second resin layer is also provided on the other side where the first resin layer is bonded to the fiber layer. The second resin layer contains one or more of polyester resin, polyurethane resin, polycarbonate resin, polyolefin resin, acrylic resin, polyimide resin, polyamide resin, aramid resin, or fluororesin.

[0033] The polyester resin mentioned refers to a heterochain polymer with ester groups on its main chain. Examples include polyethylene terephthalate, polybutylene terephthalate, polycyclohexamethylene terephthalate, polyethylene trimellitate, polybutylene phenyltrimethylolphthalate, ethylparaben, neopentyl isophthalate, polylactic acid, polybutylene adipate terephthalate, polybutylene succinate, polybutylene adipate succinate, polycaprolactone, polybutyrolactone, and copolymers of the above chemical structures with other chemical structures.

[0034] The polyurethane resin may be the polyurethane resin used in the first resin layer, or it may be a polyurethane resin of a different type than the first resin layer mentioned above.

[0035] The polycarbonate resin mentioned refers to a polymer resin containing carbonate groups in its main chain. Polycarbonate resins can be synthesized through transesterification of carbonate diesters or by the phosgene process. Examples of carbonate diesters include diphenyl carbonate, substituted diphenyl carbonates represented by dibenzyl carbonate, dimethyl carbonate, or di-tert-butyl carbonate. These carbonate diesters can be used alone or in combination. Specifically, polycarbonate resins can include bisphenol A type polycarbonate, chlorinated polycarbonate, allyl diethylene glycol carbonate, and copolymers of the above chemical structures with other chemical structures.

[0036] The polyolefin resin refers to a resin obtained by polymerization or copolymerization of one or more olefins, including ethylene, propylene, butene, pentene, or norbornene. Specifically, polyolefin resins can include high-density polyethylene, low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, polynorbornene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-vinyl acetate copolymers, and copolymers of the above chemical structures with other chemical structures.

[0037] The acrylic resin may be the acrylic resin used in the first resin layer, or it may be an acrylic resin of a different type than the one used in the first resin layer.

[0038] The polyimide resin is a polymer containing imide groups in its main chain, including condensation-type aromatic polyimides and addition-type polyimides. Specifically, examples include pyromellitic polyimides, bismaleimides, PMR polyimides, acetylene-terminated polyimides, and copolymers of the above chemical structures with other chemical structures.

[0039] The polyamide resin mentioned above, also known as nylon, can include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 46, or nylon 1010, etc.

[0040] The aramid resin, i.e., aromatic polyamide, includes para-aramid, meta-aramid, or copolymers thereof.

[0041] The fluororesin may be the fluororesin used in the first resin layer, or it may be a fluororesin of a different type than the first resin layer mentioned above.

[0042] Specifically, considering cost and availability of raw materials, the second resin layer may contain one or more of the following: polyethylene terephthalate, thermoplastic polyurethane, bisphenol A polycarbonate, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, polyethylene, polypropylene, polypropylene / polyethylene copolymer or blend.

[0043] The thickness of the second resin layer is not particularly required and can be 10 to 200 μm. From the perspective of usability and cost, it is preferred to be 20 to 100 μm.

[0044] The peel strength between the first resin layer and the second resin layer can be 0.02 to 30 N / cm. Considering the application scenario, it is preferably 0.1 to 10.0 N / cm.

[0045] The present invention also provides a vacuum forming method, comprising laying the composite film on a mold, then stacking one or more layers of fiberglass cloth and / or carbon fiber cloth, and performing vacuum filling and curing.

[0046] The present invention also provides molded articles obtained by the above method.

[0047] The vacuum forming method and the molded product described above can be applied to molding processes related to wind turbine blades, automobiles, trains, airplanes, electronic components, and molded decorative panels. Through the laying and co-molding of the composite film, the first resin layer of the composite film can be transferred to the surface of the molded product, imparting the functionality of the first resin layer to the product. This eliminates the need for high-dust and high-VOC emissions processes such as grinding and functional layer coating on the surface of the molded product, which are required in existing methods.

[0048] This invention proposes a composite film comprising a fiber layer and a first resin layer, exhibiting moderate stiffness and ease of installation. By combining the fiber layer with the resin layer, the functionality of the resin layer is retained while improving the overall usability of the composite film. This composite film can be used in fields such as heat transfer printing, particularly in vacuum forming, where the functional layer can be directly transferred to the surface of the molded product. This eliminates the high dust and VOC emissions associated with existing methods, achieving the beneficial effects of high-efficiency production, high dimensional accuracy, low resin surface pollution, and an environmentally friendly production process. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the stiffness test according to the present invention. Detailed Implementation

[0050] The present invention will be described in more detail through the following embodiments, but the embodiments do not constitute a limitation of the present invention.

[0051] 1. Raw materials

[0052] (1) Thin film raw materials

[0053]

Fiber layer

[0054] A1: Glass fiber (85wt%), thickness 0.1 mm, areal density 20 g / m³ 2 Surface roughness 0.5 micrometers, Taishan fiberglass.

[0055] A2: Glass fiber (99wt%), 2 mm thick, areal density 2500 g / m³ 2 Surface roughness 100 micrometers, Taishan fiberglass.

[0056] A3: Glass fiber (90wt%), thickness 0.15 mm, areal density 30 g / m³ 2 Surface roughness 0.8 micrometers, Taishan fiberglass.

[0057] A4: Glass fiber (98wt%), thickness 0.5 mm, areal density 1500 g / m³ 2 Surface roughness 2.5 micrometers, Taishan fiberglass.

[0058] A5: Glass fiber (95wt%), thickness 0.3 mm, areal density 850 g / m³ 2 Surface roughness 1.6 micrometers, Taishan fiberglass.

[0059] A6: Carbon fiber (85wt%), thickness 0.05 mm, areal density 10 g / m³ 2 Surface roughness 0.5 micrometers, Taishan fiberglass.

[0060] A7: Carbon fiber (100wt%), 0.5 mm thick, areal density 500 g / m³ 2 Surface roughness 1.5 micrometers, Toray.

[0061] First resin layer

[0062] B1: Jotun Paints (Zhangjiagang) Co., Ltd. produces BC100A / B, where BC100A is the main agent with a solid content of 76%, and its main component is polyester polyol compounds; BC100B is the curing agent with a solid content of 90%, and its main component is isocyanate compounds. After mixing BC100A:BC100B at a mass ratio of 6:1, it is ready for use. The standard curing conditions for this coating are 23℃ and 144 hours. By adjusting the curing temperature and time, samples with different degrees of curing can be obtained.

[0063] B2: Shanghai Mecca Coatings Co., Ltd. produces WU233A / B, where WU233A is the main agent with a solid content of 97%, and its main component is a polyurethane compound; WU233B is the curing agent with a solid content of 99%, and its main component is hexamethylene diisocyanate trimer. After mixing WU233A:WU233B at a mass ratio of 3:2, it is ready for use. The standard curing conditions for this coating are 23℃ and 24 hours. By adjusting the curing temperature and time, samples with different degrees of curing can be obtained.

[0064] B3: JH-8152 / 3390 produced by Junhe Chemical (Shanghai) Co., Ltd.: JH-8152 is the main agent, with a solid content of 95%, and its main component is polyaspartic acid ester compounds; 3390 is the curing agent, with a solid content of 98%, and its main component is hexamethylene diisocyanate trimer. After mixing JH-8152 and 3390 at a mass ratio of 4:5, the mixture is ready for use. The standard curing conditions for this coating are 23℃ and 24 hours. By adjusting the curing temperature and time, samples with different degrees of curing can be obtained.

[0065] [Second Resin Layer]

[0066] C1: Biaxially oriented polypropylene film manufactured by Toray Industries, Inc. 30-2500H, with a thickness of 30μm.

[0067] C2: Polyethylene terephthalate produced by Toray Industries, Inc. T60, thickness 125μm.

[0068] C3: Polyolefin film produced by Toray Industries, Inc. 7H55G, thickness 30μm.

[0069] (2) Other

[0070] Adhesive spray: Multi-functional high-strength adhesive spray, Li & Fung Technology.

[0071] Release agent: FREKOTE 55-NC, Henkel.

[0072] 2. The methods for determining the relevant performance in the embodiments and comparative examples of the present invention are as follows: for all tests, unless otherwise specified, the test temperature is 23°C.

[0073] (1) thickness: Thickness gauge (Mitutoyo digital thickness gauge 541-401, Japan)

[0074] Ten different locations were selected for measurement of each sample, and the arithmetic mean of the thickness at the ten locations was taken as the thickness of the sample.

[0075] (2) areal density: Electronic balance (Mettler-Toledo ML204T China)

[0076] Sample size: 50mm × 50mm

[0077] Weigh the sample piece and then calculate the areal density according to Formula 1 below.

[0078]

[0079] Five samples were measured for each sample, and the arithmetic mean of the five test results was taken as the areal density of the sample.

[0080] (3) Degree of crosslinking: Dynamic thermomechanical analyzer (TADMAQ800, USA)

[0081] Spline size: 50mm × 10mm.

[0082] Test conditions: thin film stretching mode, 25℃-200℃, heating rate 3℃ / min, vibration frequency 1Hz, amplitude 100 micrometers.

[0083] After the test, the energy storage modulus at 35℃ was read from the test curve, and the degree of crosslinking was calculated according to Formula 2 below.

[0084]

[0085] Note: Extending the curing time of the sample will gradually increase the storage modulus obtained from the DMA test. When the curing time is extended to a certain extent, the storage modulus will tend to stabilize. At this point, the system is considered to be fully cured, and the corresponding storage modulus is the storage modulus of the fully cured sample. The curing process can also be accelerated by heat-treating the sample at 150℃ for 8 hours.

[0086] Three specimens were measured for each sample, and the arithmetic mean of the three test results was taken as the crosslinking degree of the sample.

[0087] (4) Peel strength: Tensile testing machine (Shimadzu AG-IS1KN Japan)

[0088] When conducting tests between the two layers, the upper layer was reinforced with TESA 7475 test tape, with the reinforced area measuring 150mm × 10mm. A tensile testing machine was then used to perform a 180° peel strength test at a tensile speed of 200mm / min.

[0089] For each sample, different areas were selected and measured three times. The arithmetic mean of the three test results was taken as the peel strength result.

[0090] (5) Stiffness: according to Figure 1 The method shown measures

[0091] A 15cm x 1cm test film is cut, with 5cm of its length fixed to the test stage using a glass plate (thickness ≥ 0.5cm, width ≥ 20cm, length ≥ 30cm, weight > 700g to ensure stable fixation). The remaining 10cm is suspended in the air. The height of the suspended portion perpendicular to the glass plate is measured, yielding the sag height h. The stiffness of the film is calculated by subtracting the sag height h from 10cm. The test range for this method is 0-10cm. When the stiffness is 0cm, the unfixed area of ​​the film sags completely to a height of 10cm, indicating the worst film stiffness. When the stiffness is 10cm, the film is not easily bent, has a sag height of 0cm, and exhibits the same high stiffness as the glass plate.

[0092] Three samples were taken from each sample and tested. The arithmetic mean of the three test results was taken as the stiffness result.

[0093] (6) Surface roughness: Stylus-type roughness profile tester (Xiamen Jinheyuan TR200 China)

[0094] The test speed was 0.5 mm / s.

[0095] For each sample, different areas were measured three times, and the arithmetic mean of the three test results was taken as the surface roughness result. For the fiber layer, the test surface was always the surface adjacent to the first resin layer.

[0096] (7) Laying speed:

[0097] A certain amount of test film was cut and placed in a 1m × 0.5m area. 2The film was laid on an epoxy resin board for testing. Using a mop head measuring 45cm (length) × 15cm (width), air bubbles were removed at a speed of 3m / min. The time from the start of bonding until no air bubbles larger than 5mm in diameter remained on the bonding surface, or until the bonding surface was adjusted to its optimal state (although wrinkles or air bubbles still existed, repeated peeling and re-bonding could not further improve the bonding appearance), was recorded as the film laying time T (min).

[0098] The test film laying speed = laying area S / laying time T, where S = 0.5m 2

[0099] The layup speed of the composite film = 0.5 / T (m) 2 ( / min), each sample was tested 3 times, and the arithmetic mean of the 3 test results was taken as the laying speed result.

[0100] If the test film is prone to sliding on the mold and cannot be adhered, it can be fixed using adhesive spraying. The test strips are overlapped directly.

[0101] The appearance of the paved area shall be evaluated according to the following standards:

[0102] Good: The test film can be smoothly and tightly adhered to the mold surface, with no visible wrinkles, and no visible areas that are suspended above the mold or cannot adhere to the mold.

[0103] Wrinkles: The test film can adhere tightly to the mold surface, with no visible areas that are suspended above the mold or cannot adhere to the mold, but the test film has visible wrinkles that cannot be flattened.

[0104] Unable to be laid: The test film cannot be tightly adhered to the mold surface, and there are visible areas that are suspended above the mold and cannot adhere to the mold.

[0105] (8) Vacuum forming:

[0106] The composite films obtained in the examples and comparative examples were laid on a substrate pre-coated with a release agent. The composite film of the present invention is laid on an epoxy resin board (60 cm × 60 cm) of FREKOTE 55-NC. Then, 8 layers of glass fiber (Taishan glass fiber, triaxial, 1200 g / m²) are laid on the fiber layer surface of the composite film of the present invention. 2This process involves mixing Dow Chemical's Airstone series 760E / 766H epoxy resin at a mass ratio of 100:32, followed by vacuum infusion. The mixture is then cured at 50°C for 5 hours, followed by curing at 75°C for 7 hours, resulting in a 6mm thick epoxy resin molded product. After vacuum infusion, the epoxy permeates the fiber layer of the composite film, thus contacting the first resin layer. After curing, demolding is performed, and the first resin layer transfers to the surface of the molded product, directly becoming its functional surface.

[0107] The appearance of the molded product shall be evaluated according to the following criteria:

[0108] Good: After demolding, the outer surface of the molded part is smooth and flat, with no visible wrinkles or areas where the film and epoxy resin have separated.

[0109] Wrinkles: After demolding, the outer surface of the molded part is basically smooth and flat, with no visible areas of separation between the film and epoxy resin, but there are visible wrinkles.

[0110] Fiberglass texture: After demolding, the outer surface of the molded part is basically smooth and flat, without visible wrinkles or areas where the film and epoxy resin are separated, but there are visible fiberglass textures.

[0111] The fiberglass texture is very deep: after the molded part is demolded, there is no visible area where the film and epoxy resin have separated, but the fiberglass texture on the outer surface of the molded part is obvious.

[0112] Unable to be molded: If, after demolding, there are areas on the outer surface of the molded part where the film and epoxy resin are detached and visible to the naked eye, the molding process is considered to have failed and the part cannot be molded.

[0113] (9) Transferability of the first resin layer:

[0114] For composite films containing both a first resin layer and a second resin layer, the transferability of the first resin layer also needs to be considered. According to the method of [(8) vacuum forming], after molding and demolding, the first resin layer and / or the second resin layer are transferred to the surface of the molded article. When the first and second resin layers are transferred to the surface of the molded article simultaneously, the second resin layer needs to be peeled off so that the first resin layer becomes the functional surface of the molded article. The surface of the molded article after transfer and the transfer glass surface adjacent to the first resin layer are measured by infrared spectroscopy. Based on the measurement results of the two surface components, the following judgments are made:

[0115] 〇: Excellent transferability; the first resin layer can be completely peeled off from the surface of the second resin layer and firmly adhered to the outer surface of the molded article; no components of the second resin layer can be detected on the outer surface of the molded article.

[0116] △: In the transferability, the components of the first resin layer are detected on both surfaces, but the first resin layer can be peeled off from the second resin layer without cracking; or the second resin layer is directly detached from the first resin layer during molding and demolding.

[0117] ×: Poor transferability; the first resin layer is torn and cannot be completely peeled off from the surface of the second resin layer; or the second resin layer is torn and cannot be completely peeled off from the surface of the first resin layer.

[0118] (10) Composite of fiber layer and first resin layer: Flatbed Hot Press (TOYOSEIKI MP-FH, Japan)

[0119] The working pressure is 20 MPa, and the temperature and time are set in detail according to the example.

[0120] Example 1

[0121] (1) Preparation of the first resin layer

[0122] After blending 60g of the main agent BC100A and 10g of the curing agent BC100B, the mixture was applied to a C3 substrate using a wet film preparation device. After drying at 100°C for 10 minutes, the coating was peeled off the substrate to obtain a separate first resin layer B1a with a thickness of 50 micrometers.

[0123] At this point, the degree of crosslinking of the first resin layer B1a is 20%.

[0124] (2) Preparation of composite films

[0125] A small amount of adhesive that is visible to the naked eye is sprayed onto the surface of the fiber layer A1, and then the first resin layer is covered on top. After the adhesive has cured, a composite film with the structure of fiber layer A1 / first resin layer is obtained.

[0126] Various properties of the obtained composite film were measured, and the results are listed in Table 1.

[0127] Examples 2-5

[0128] By replacing fiber layer A1 in Example 1 with fiber layers A2-A5, different composite films were obtained.

[0129] Various properties of the obtained composite film were measured, and the results are listed in Table 1.

[0130] Comparative Example 1

[0131] The first resin layer B1a obtained in step (1) of Example 1 was used as a thin film sample, and various performance tests were performed. The results are listed in Table 2.

[0132] Comparative Example 2

[0133] Adjust the thickness of the wet film preparation device in step (1) of Example 1, and after drying and curing at room temperature for 3 days and 50°C for 5 days, peel off the coating from the substrate to obtain a separate first resin layer B1b with a thickness of 800 micrometers.

[0134] At this point, the degree of crosslinking of the first resin layer B1b is 100%. Various performance tests were performed on it, and the results are listed in Table 2.

[0135] Comparative Example 3

[0136] 60g of the main agent BC100A and 10g of the curing agent BC100B were mixed and poured into a mold coated with a release agent. After curing at 50°C for 24 hours, a resin plate B1c with a thickness of 5000 micrometers was obtained. Various performance tests were performed, and the results are listed in Table 2.

[0137] Comparative Example 4-5

[0138] By replacing the fiber layer and the first resin layer in Example 1, different composite films can be obtained.

[0139] Various properties of the obtained composite film were measured, and the results are listed in Table 2.

[0140] Table 1

[0141]

[0142] Table 2

[0143]

[0144] As shown in Tables 1 and 2, while the stiffness value can be adjusted by changing the thickness of the first resin layer during layup, problems such as poor layup and poor finished appearance still occur due to the poor spreadability of the resin layer alone. Furthermore, when simply combining the first resin layer and the fiber layer, the introduction of the fiber layer can improve the stiffness of the composite film, potentially increasing layup speed or causing excessive stiffness that prevents layup. However, if the peel strength is too low or too high, the effect is unsatisfactory. Optimizing the selection of the first resin layer and the fiber layer can significantly improve the stiffness of the composite film, resulting in higher layup speed and better layup and finished appearance.

[0145] As can be seen from Examples 1-5, as the thickness and areal density of the fiber layer increase, the stiffness of the composite film increases, and the corresponding laying speed first increases and then decreases. This is because when the stiffness increases, the composite film first becomes easier to stretch and less prone to wrinkles, thus increasing the laying speed; however, when the stiffness is further increased, the composite film becomes too rigid and not easy to deform, requiring more time to adjust for fitting with the mold during laying.

[0146] Example 6

[0147] The first resin layer B1a in Example 3 was further cured at 50°C for 5 days to obtain a separate first resin layer B1d with a thickness of 50 micrometers.

[0148] At this point, the degree of crosslinking of the first resin layer B1d is 100%.

[0149] Then, using the same fiber layer and composite process as in Example 3, a composite film was obtained.

[0150] Various properties of the obtained composite film were measured, and the results are listed in Table 3.

[0151] Example 7

[0152] The curing conditions of the first resin layer B1d in Example 6 were changed to room temperature for 3 days to obtain a separate first resin layer B1e with a thickness of 50 micrometers.

[0153] At this point, the degree of crosslinking of the first resin layer B1e is 40%.

[0154] Then, using the same fiber layer and composite process as in Example 3, a composite film was obtained.

[0155] Various properties of the obtained composite film were measured, and the results are listed in Table 3.

[0156] Example 8

[0157] The curing conditions of the first resin layer B1d in Example 6 were changed to 30°C for 3 days to obtain a separate first resin layer B1f with a thickness of 50 micrometers.

[0158] At this point, the degree of crosslinking of the first resin layer B1f is 65%.

[0159] Then, using the same fiber layer and composite process as in Example 3, a composite film was obtained.

[0160] Various properties of the obtained composite film were measured, and the results are listed in Table 3.

[0161] Example 9

[0162] The curing conditions of the first resin layer B1d in Example 6 were changed to 50°C for 3 days to obtain a separate first resin layer B1g with a thickness of 50 micrometers.

[0163] At this point, the degree of crosslinking of the first resin layer B1g is 85%.

[0164] Then, using the same fiber layer and composite process as in Example 3, a composite film was obtained.

[0165] Various properties of the obtained composite film were measured, and the results are listed in Table 3.

[0166] Table 3

[0167]

[0168] As shown in Table 3, and in conjunction with Example 3, as the degree of crosslinking of the first resin layer increases, the stiffness of the resin layer itself increases, and the stiffness of the composite film also increases accordingly, while the laying speed first increases and then decreases.

[0169] Examples 10-13

[0170] Adjust the thickness of the wet film preparation device in step (1) of Example 3, and after drying at room temperature for 3 days, peel the coating off the substrate to obtain a first resin layer B1h-B1k with individual thickness adjustment.

[0171] At this point, the degree of crosslinking of the first resin layers B1h-B1k is 20%.

[0172] Then, using the same fiber layer and composite process as in Example 3, a composite film was obtained.

[0173] Various properties of the obtained composite film were measured, and the results are listed in Table 4.

[0174] Table 4

[0175]

[0176] As shown in Table 4, and in conjunction with Example 3, as the thickness of the first resin layer increases, the stiffness of the resin layer itself increases, and the stiffness of the composite film also increases accordingly, while the laying speed first increases and then decreases.

[0177] Example 14

[0178] (1) Preparation of the first resin layer

[0179] 60g of the main agent BC100A and 10g of the curing agent BC100B were blended and then coated onto the C1 substrate using a wet film preparation device. After drying at 100°C for 10 minutes, a two-layer structure of first resin layer B1a and second resin layer C1 was obtained.

[0180] The thickness of the first resin layer B1a is 50 micrometers, and the degree of crosslinking is 20%.

[0181] (2) Preparation of composite films

[0182] A small amount of adhesive that is visible to the naked eye is sprayed onto the surface of fiber layer A3, and then the two-layer structure sample obtained in step (1) is covered on it. After the adhesive is cured, a composite film with the structure of fiber layer A3 / first resin layer B1a / second resin layer C1 is obtained.

[0183] Various properties of the obtained composite film were measured, and the results are listed in Table 5.

[0184] Examples 15-16

[0185] By changing the fiber layer, the raw materials of the first resin layer, the coating and curing conditions, and the second resin layer in Example 14, composite films of Examples 15 and 16 were obtained.

[0186] Various properties of the obtained composite film were measured, and the results are listed in Table 5.

[0187] Example 17

[0188] A small amount of adhesive was sprayed onto the surface of the fiber layer of the composite film with the structure of fiber layer A3 / first resin layer obtained in Example 3, and then fiber layer A4 was covered on top. After the adhesive was cured, a composite film with the structure of fiber layer A4 / fiber layer A3 / first resin layer was obtained.

[0189] Various properties of the obtained composite film were measured, and the results are listed in Table 5.

[0190] Table 5

[0191]

[0192] As can be seen from Examples 14-16 in Table 5 and in conjunction with Example 3, the introduction of the second resin layer can improve the stiffness of the composite film, thereby increasing the layup speed. Comparing Examples 14-16 further reveals that adjusting the peel strength between the first and second resin layers can affect the transferability of the molded product. Increasing the peel strength between the first and second resin layers makes it easier for the second resin layer to remain on the surface of the first resin layer after molding and demolding, thus protecting the first resin layer. However, if the peel strength between the first and second resin layers is too high, the second resin layer will be difficult to peel from the surface of the first resin layer, affecting the transferability of the first resin layer.

[0193] As can be seen from Example 17 in Table 5, combined with Examples 3 and 4, the superposition of two fiber layers with different properties can further reduce the stiffness of the composite film, thereby increasing the laying speed.

[0194] Example 18

[0195] (1) Preparation of the first resin layer

[0196] 60g of the main agent BC100A and 10g of the curing agent BC100B were blended and then coated onto a C3 substrate using a wet film preparation device. After drying at 60°C for 10 minutes, a first resin layer, B1a / C3 substrate, was obtained with a dry surface. The thickness of the solids layer was 50 micrometers.

[0197] (2) Preparation of composite films

[0198] Fiber layer A2 is placed on the upper surface of the first resin layer B1a, which has a dried surface and has a C3 substrate. After hot pressing on a flat plate at 80°C for 3 minutes, a composite film with the structure of fiber layer 2 / first resin layer is obtained.

[0199] Various properties of the obtained composite film were measured, and the results are listed in Table 6.

[0200] Example 19

[0201] The drying conditions for the first resin layer were modified to 60°C for 5 minutes, otherwise the same as in Example 18.

[0202] Example 20

[0203] The drying conditions for the first resin layer were modified to 40°C and placed for 5 minutes, otherwise the same as in Example 18.

[0204] Example 21

[0205] The drying conditions for the first resin layer were modified to be left at room temperature for 5 minutes, otherwise the same as in Example 18.

[0206] Table 6

[0207]

[0208] As can be seen from Examples 18-21 in Table 6 and in conjunction with Example 2, adjusting the drying condition of the first resin layer can improve the peel strength between the first resin layer and the fiber layer of the composite film, thereby increasing the laying speed. Hot-pressing the first resin layer with the fiber layer before it is completely dry facilitates the formation of a fiber-infiltrated resin layer structure, which significantly improves the peel strength.

Claims

1. A composite film, characterized by: The composite film contains a first resin layer and a fiber layer, and has a stiffness of 2.0-9.9 cm. The first resin layer contains one or more of thermosetting polyurethane resin, thermosetting epoxy resin, or thermosetting acrylic resin. The stiffness test method is as follows: a 15 cm × 1 cm test film is cut, with 5 cm fixed to the test stage with a glass plate in the length direction, and the remaining 10 cm suspended in the air. The height of the suspended part in the vertical direction of the glass plate is measured to obtain the droop height h. The stiffness of the film is obtained by subtracting the droop height h from 10 cm.

2. The composite film of claim 1, wherein: The thickness of the fiber layer is 0.1-2.0 mm.

3. The composite film of claim 1, wherein: The areal density of the fibre layer is 20-2500 g / m 2 .

4. The composite film of claim 3, wherein: The areal density of the fibre layer is 20-1600 g / m 2 .

5. The composite film of claim 1, wherein: The surface roughness of the interface between the fiber layer and the first resin layer is 0.5-100 μm.

6. The composite film of claim 5, wherein: The surface roughness of the interface between the fiber layer and the first resin layer is 0.5-10 μm.

7. The composite film of claim 1, wherein: When the fiber layer has a mass of 100 parts by weight, the fiber layer contains more than 85 parts by weight of glass fiber and / or carbon fiber.

8. The composite film of claim 1, wherein: The first resin layer and the fiber layer are adjacent to each other, and the peel strength is 0.01-200 N / cm.

9. The composite film of claim 1, wherein: The stiffness is 3.0-8.5cm.

10. The composite film of claim 1, wherein: The degree of crosslinking of the first resin layer is 20-100%.

11. The composite film of claim 1, wherein: The thickness of the first resin layer is 50-500 μm.

12. The composite film of claim 1, wherein: The stiffness of the first resin layer is 0-7cm.

13. The composite film of claim 1, wherein: A second resin layer is provided on the other side of the fiber layer side of the first resin layer, and the second resin layer contains one or more of polyester resin, polyurethane resin, polycarbonate resin, polyolefin resin, acrylic resin, polyimide resin, polyamide resin, aramid resin or fluororesin.

14. The composite film of claim 13, wherein: The peel strength of the first resin layer and the second resin layer is 0.02-30.0 N / cm.

15. A vacuum forming method comprising laying a composite film as described in any one of claims 1-14 on a mold, and then stacking one or more layers of fiberglass cloth and / or carbon fiber cloth, followed by vacuum filling and curing.

16. A molded article prepared by the vacuum forming method according to claim 15.

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