End-capped modified curing agent and preparation method thereof, adhesive for wet peelable cloth and preparation method thereof, and preparation method of wet peelable cloth

Abstract

The invention belongs to the technical field of peelable cloth, and particularly relates to an end-capped modified curing agent and a preparation method thereof, an adhesive for wet peelable cloth and a preparation method thereof, and a preparation method of the wet peelable cloth. The blocking curing agent prepared from the polyaryletherketone copolymer containing the aldehyde group at the tail end and 4 '4-diaminodiphenyl sulfone is applied to the wet strippable cloth, and the exposed amino active group of the curing agent can participate in the curing process of the epoxy composite material in the first step; meanwhile, the blocking curing agent is unblocked, imine bonds are hydrolyzed under the assistance of hydroxyl, more amino active groups are released, and meanwhile, aldehyde groups generated after hydrolysis can also participate in the subsequent secondary cementing process. The wet peelable cloth can form a'hand-in-hand 'bridging effect between the surface of the composite material and the adhesive film, and the adhesive effect of the adhesive film during secondary adhesive bonding is improved.

Description

Technical Field

[0001] This invention belongs to the field of peelable fabric technology, specifically relating to an end-capping modified curing agent and its preparation method, an adhesive for wet peelable fabric and its preparation method, and a method for preparing wet peelable fabric. Background Technology

[0002] With technological advancements, carbon fiber composite materials are widely used in the manufacture of structural components to meet the design requirements of various national defense and civilian aircraft. Traditional methods for improving the surface roughness of composite materials typically involve manual grinding and sandblasting. However, these methods suffer from poor process stability and fiber damage. Another method for surface treatment involves co-curing a dry peelable fabric with a complex texture with the composite material, then removing the fabric to create a rough surface. However, removing the fabric removes resin from the composite material surface, resulting in poor adhesive retention and affecting the stability of secondary bonding. Using a wet peelable fabric for surface pretreatment not only improves surface roughness but also ensures the stability and strength of secondary bonding. Currently, there are few patents addressing this issue. Existing technology discloses a synergistic surface treatment method to improve the bonding performance of carbon fiber composite materials. This method uses a peelable fabric to create a rough texture on the composite material surface and then uses plasma treatment to improve the bonding effect during secondary bonding. However, this requires additional plasma equipment in practical applications, leading to significant waste of manpower and resources and failing to meet market demands. Summary of the Invention

[0003] The purpose of this invention is to provide an end-capping modified curing agent and its preparation method, an adhesive for wet peelable fabric and its preparation method, and a method for preparing wet peelable fabric.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing an end-capped modified curing agent, comprising the following steps: The reactants, catalyst, and organic solvent are first mixed and reacted. Then, a capping agent is added and a second reaction is carried out to obtain a polyarylether ketone copolymer with aldehyde groups at the end. The reactants are 4,4-difluorobenzophenone, bisphenol A, and biphenyl; the capping agent is 4-tert-butyl-2-oxosodium benzaldehyde. The end-capped modified curing agent is obtained by second mixing the polyarylether ketone copolymer with aldehyde groups at the end, 4',4-diaminodiphenyl sulfone, catalyst and organic solvent, and then carrying out a third reaction.

[0005] Preferably, in the first mixture, the molar ratio of 4,4-difluorobenzophenone, bisphenol A, and biphenyl is 1~1.05:0.6~0.65:0.4~0.45; The catalyst comprises anhydrous potassium carbonate; the molar amount of the catalyst is 1.1 to 1.12 times the total molar amount of bisphenol A and biphenyl hydroquinone.

[0006] Preferably, the temperature of the first reaction is 170~190℃, and the holding time is 8~10h; The first reaction was carried out under a protective atmosphere.

[0007] Preferably, the molar ratio of 4,4-difluorobenzophenone to the capping agent is 1~1.05:0.08~0.1; The temperature of the second reaction is the same as that of the first reaction, and the time of the second reaction is 1 to 2 hours.

[0008] Preferably, in the second mixture, the molar ratio of the terminal aldehyde-containing polyaryletherketone copolymer to 4',4-diaminodiphenyl sulfone is 1:2; The catalyst includes acetic acid; the molar ratio of the terminal aldehyde-containing polyaryletherketone copolymer to the catalyst is 1:0.5~1; The temperature of the third reaction is 40~50℃, and the time is 4~5h.

[0009] The present invention also provides an end-capping modified curing agent prepared by the preparation method described in the above technical solution; The end-capping modified curing agent has the following structure: Where m is 20~50 and n is 1~3.

[0010] The present invention also provides an adhesive for wet peelable fabric, comprising, by weight parts: 10-40 parts epoxy resin, 20-50 parts modified epoxy resin, 8-20 parts curing agent, 5-15 parts accelerator, 10-20 parts filler and 10-20 parts solvent. The modified epoxy resin is polymethyl methacrylate-based heptaepoxy POSS; The curing agent is the end-capping modified curing agent described in the above technical solution.

[0011] Preferably, the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy epoxy resin and phenolic epoxy resin; The accelerator includes at least one of imidazole, dicyandiamide, pyromellitic anhydride, and methylhexahydrophthalic anhydride; The filler includes at least one of aluminum hydroxide, aluminum oxide, fumed silica and titanium dioxide; The solvent includes at least one of ethyl acetate, butyl acetate, butanone, toluene, and cyclohexanone.

[0012] The present invention also provides a method for preparing the adhesive for wet-peelable fabric described in the above technical solution, comprising the following steps: Epoxy resin and curing agent are mixed to obtain resin A; The modified epoxy resin and filler were mixed to obtain resin B; The resin A, resin B, accelerator and solvent are mixed to obtain the adhesive for the wet peelable fabric.

[0013] This invention also provides a method for preparing a wet-peelable fabric, comprising the following steps: After preheating, the adhesive is coated onto the surface of the release substrate and dried to obtain a film-like resin matrix; the adhesive is the wet peelable fabric adhesive described in the above technical solution or the wet peelable fabric adhesive prepared by the preparation method described in the above technical solution. The membrane resin layer on the membrane resin matrix is ​​bonded to the fabric carrier, and after the release matrix is ​​removed, the wet peelable fabric is obtained.

[0014] This invention provides a method for preparing an end-capped modified curing agent, comprising the following steps: firstly mixing a reactive monomer, a catalyst, and an organic solvent, performing a first reaction, then adding an end-capping agent, and performing a second reaction to obtain a polyarylether ketone copolymer with aldehyde groups at the end; wherein the reactive monomer is 4,4-difluorobenzophenone, bisphenol A, and biphenyl; and the end-capping agent is 4-tert-butyl-2-oxosodium benzaldehyde; secondly mixing the polyarylether ketone copolymer with aldehyde groups at the end, 4',4-diaminodiphenyl sulfone, the catalyst, and the organic solvent, and performing a third reaction to obtain the end-capped modified curing agent.

[0015] This invention utilizes a sealing and curing agent prepared from a polyaryletherketone copolymer with aldehyde-terminated ends and 4',4-diaminodiphenyl sulfone. When applied to a wet-peelable fabric, the exposed amino active groups of the curing agent participate in the first-step curing process of the epoxy composite material. Simultaneously, the sealing and curing agent deseales, and the imine bonds undergo hydrolysis with the assistance of hydroxyl groups, releasing more amino active groups. Furthermore, the aldehyde groups generated after hydrolysis can also participate in the subsequent secondary bonding process. This allows the wet-peelable fabric to form a "hand-in-hand" bridging effect between the composite material surface and the adhesive film, improving the adhesion of the adhesive film during secondary bonding.

[0016] This invention also provides an adhesive for wet-peelable fabric, comprising, by weight parts: 10-40 parts epoxy resin, 20-50 parts modified epoxy resin, 8-20 parts curing agent, 5-15 parts accelerator, 10-20 parts filler, and 10-20 parts solvent; the curing agent is the end-capping modified curing agent described in the above technical solution; the modified epoxy resin is polymethyl methacrylate-based heptaepoxy POSS. In this invention, the POSS-modified epoxy resin forms a network cross-linked structure with good heat resistance and aging resistance, improving the fatigue resistance of the composite material. The wet-peelable fabric prepared from the above adhesive is easily peeled off from the surface of the dried carbon fiber composite material, and after secondary bonding, the single lap shear strength at room temperature reaches over 27 MPa. This invention improves the adhesion and heat resistance of the system by introducing the end-capping modified curing agent and the POSS-modified epoxy resin, enabling use at 180°C. Detailed Implementation

[0017] This invention provides a method for preparing an end-capped modified curing agent, comprising the following steps: The reactants, catalyst, and organic solvent are first mixed and reacted. Then, a capping agent is added and a second reaction is carried out to obtain a polyarylether ketone copolymer with aldehyde groups at the end. The reactants are 4,4-difluorobenzophenone, bisphenol A, and biphenyl; the capping agent is 4-tert-butyl-2-oxosodium benzaldehyde. The end-capped modified curing agent is obtained by second mixing the polyarylether ketone copolymer with aldehyde groups at the end, 4',4-diaminodiphenyl sulfone, catalyst and organic solvent, and then carrying out a third reaction.

[0018] In this invention, a reactive monomer, a catalyst, and an organic solvent are first mixed and subjected to a first reaction. Then, a capping agent is added, and a second reaction is carried out to obtain a polyarylether ketone copolymer with aldehyde groups at the end. The reactive monomer is 4,4-difluorobenzophenone, bisphenol A, and biphenyl; the capping agent is 4-tert-butyl-2-oxosodium benzaldehyde.

[0019] In this invention, the molar ratio of 4,4-difluorobenzophenone, bisphenol A, and biphenyl hydroquinone is preferably 1~1.05:0.6~0.65:0.4~0.45, specifically 1.05:0.6:0.4. In this invention, the molar amount of the catalyst is 1.1~1.12 times the total molar amount of bisphenol A and biphenyl hydroquinone. In this invention, the organic solvent preferably includes sulfolane. This invention does not have a particular limitation on the amount of the organic solvent used, as long as it can uniformly disperse the components.

[0020] In this invention, the temperature of the first reaction is preferably 170~190℃, specifically 170℃, 180℃, or 190℃; the holding time is preferably 8~10h, specifically 8h, 9h, or 10h; the first reaction is preferably carried out under a protective atmosphere, preferably nitrogen.

[0021] In this invention, the capping agent is 4-tert-butyl-2-oxosodium benzaldehyde; the molar ratio of 4,4-difluorobenzophenone to the capping agent is preferably 1~1.05:0.08~0.1. In this invention, the temperature of the second reaction is preferably the same as the temperature of the first reaction, and the time of the second reaction is preferably 1~2 hours.

[0022] Following the second reaction, the present invention preferably further includes washing and drying the obtained precipitate, wherein the drying temperature is preferably 120°C and the drying time is preferably 24 hours.

[0023] After obtaining the polyaryletherketone copolymer (PAEK-CHO) with aldehyde groups at the end, the present invention further mixes the polyaryletherketone copolymer with aldehyde groups at the end, 4',4-diaminodiphenyl sulfone, catalyst and organic solvent in a second mixture and carries out a third reaction to obtain the end-capping modified curing agent.

[0024] In this invention, the molar ratio of the terminal aldehyde-containing polyaryletherketone copolymer to 4',4-diaminodiphenyl sulfone is preferably 1:2. In this invention, the catalyst preferably comprises acetic acid; the molar ratio of the terminal aldehyde-containing polyaryletherketone copolymer to the catalyst is 1:0.5~1. In this invention, the organic solvent preferably comprises dichloromethane and methanol, and the volume ratio of dichloromethane to methanol is preferably 1~3:1. This invention does not have a particular limitation on the amount of the organic solvent used, as long as it can uniformly disperse the components.

[0025] In this invention, the temperature of the third reaction is preferably 40-50°C, and the time is preferably 4-5 hours. In this invention, after the third reaction, it is also preferable to further include precipitating the obtained system with n-hexane, filtering it, washing it with cold methanol, and finally vacuum drying it; the vacuum drying time is preferably 12-24 hours.

[0026] In this invention, the chemical equation for preparing the end-capped modified curing agent is as follows: .

[0027] The present invention also provides an end-capping modified curing agent prepared by the preparation method described in the above technical solution; the end-capping modified curing agent has the following structure: Where m is 20~50 and n is 1~3.

[0028] The present invention also provides an adhesive for wet peelable fabric, comprising, by weight parts: 10-40 parts epoxy resin, 20-50 parts modified epoxy resin, 8-20 parts curing agent, 5-15 parts accelerator, 10-20 parts filler and 10-20 parts solvent. The modified epoxy resin is polymethyl methacrylate-based heptaepoxy POSS; The curing agent is the end-capping modified curing agent described in the above technical solution.

[0029] The adhesive for wet-peelable fabrics provided by this invention comprises 10 to 40 parts by weight, specifically 10, 20, 30, or 40 parts of epoxy resin. In this invention, the epoxy resin preferably comprises at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy epoxy resin, and phenolic epoxy resin.

[0030] Based on the mass fraction of the epoxy resin, the adhesive for wet-peelable fabric provided by the present invention comprises 20-50 parts of modified epoxy resin, specifically 20 parts, 30 parts, 40 parts, or 50 parts. In the present invention, the modified epoxy resin is polymethyl methacrylate-based heptaepoxy POSS.

[0031] In this invention, the preferred structural formula of the polymethacrylate-based heptaepoxide POSS is as follows: Where R is ; m is 190~250, and n is 5~10.

[0032] In this invention, the polymethacrylate-based heptaepoxy POSS is specifically described in patent publication number CN112358849A.

[0033] In this invention, the use of polymethacrylate-based hepta-epoxy POSS can improve the flexibility of epoxy resin, effectively alleviate the internal stress caused by material curing shrinkage, and improve the heat resistance and weather resistance of epoxy resin. By compounding the modified epoxy resin with conventional epoxy resin, a three-dimensional network polymer is formed, which effectively improves the heat resistance and aging resistance of the resin.

[0034] Based on the mass fraction of the epoxy resin, the adhesive for wet peelable fabric provided by the present invention includes 8 to 20 parts of curing agent, specifically 8, 10, 12, 14, 16, 18, or 20 parts; the curing agent is the end-capping modified curing agent described in the above technical solution.

[0035] Based on the mass fraction of the epoxy resin, the adhesive for wet-peelable fabric provided by the present invention includes 5 to 15 parts of an accelerator, specifically 5 parts, 8 parts, 10 parts, 12 parts, or 15 parts. In the present invention, the accelerator preferably includes at least one of imidazole, dicyandiamide, pyromellitic anhydride, and methylhexahydrophthalic anhydride.

[0036] Based on the mass fraction of the epoxy resin, the adhesive for wet-peelable fabric provided by the present invention comprises 10 to 20 parts of filler, specifically 10, 12, 14, 16, 18, or 20 parts. In the present invention, the filler preferably comprises at least one of aluminum hydroxide, alumina, fumed silica, and titanium dioxide.

[0037] Based on the mass fraction of the epoxy resin, the adhesive for wet-peelable fabric provided by the present invention comprises 10 to 20 parts of solvent, specifically 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts. In the present invention, the solvent preferably includes at least one selected from ethyl acetate, butyl acetate, butanone, toluene, and cyclohexanone.

[0038] The present invention also provides a method for preparing the adhesive for wet-peelable fabric described in the above technical solution, comprising the following steps: Epoxy resin and curing agent are mixed to obtain resin A; The modified epoxy resin and filler were mixed to obtain resin B; The resin A, resin B, accelerator and solvent are mixed to obtain the adhesive for the wet peelable fabric. This invention involves mixing epoxy resin and a curing agent to obtain resin A. In this invention, the mixing is preferably carried out under stirring conditions, the stirring temperature is preferably room temperature, and the stirring time is preferably 30-120 minutes.

[0039] This invention involves mixing modified epoxy resin and filler to obtain resin B. In this invention, the mixing is preferably carried out under closed stirring conditions, with the stirring temperature preferably at room temperature and the stirring time preferably between 30 and 60 minutes.

[0040] After obtaining resin A and resin B, the present invention mixes resin A, resin B, accelerator, and solvent to obtain the adhesive for wet peelable fabric. In the present invention, the mixing preferably includes: adding resin A and resin B to a dispersion mill, and adding accelerator and solvent for dilution; the dilution is preferably carried out under stirring conditions, and the stirring time is preferably 30-120 minutes.

[0041] This invention also provides a method for preparing a wet-peelable fabric, comprising the following steps: After preheating, the adhesive is coated onto the surface of the release substrate and dried to obtain a film-like resin matrix; the adhesive is the wet peelable fabric adhesive described in the above technical solution or the wet peelable fabric adhesive prepared by the preparation method described in the above technical solution. The membrane resin layer on the membrane resin matrix is ​​bonded to the fabric carrier, and after the release matrix is ​​removed, the wet peelable fabric is obtained.

[0042] This invention involves preheating the adhesive compound, coating it onto the surface of a release substrate, and then drying it to obtain a film-like resin matrix. In this invention, the preheating temperature is preferably 30-50°C, and the preheating time is preferably 10-30 minutes. In this invention, the release substrate is preferably a PET release substrate. This invention does not impose any special limitations on the coating process; any process well-known to those skilled in the art can be used. In this invention, the drying temperature is preferably 70-130°C, and the drying time is preferably 3-15 minutes.

[0043] After obtaining the film-like resin matrix, the present invention laminates the film-like resin layer on the film-like resin matrix with a fabric carrier, and after removing the release liner, obtains the wet-peelable fabric. In the present invention, the fabric carrier preferably includes an NS-230 type fabric carrier (produced by Jiangsu Aihe Composite Materials Co., Ltd.). In the present invention, the lamination method is preferably performed under hot-pressing conditions. In the present invention, the hot-pressing temperature is preferably 120~180℃, and the pressure is preferably 0.1~0.9MPa.

[0044] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0045] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0046] Example 1 1.05 mol of 4,4-difluorobenzophenone, 0.6 mol of bisphenol A, and 0.4 mol of biphenyl hydroquinone were added to 180 mL of sulfolane. The mixture was heated to 180 °C and kept at this temperature for 9 h under a nitrogen atmosphere and with anhydrous potassium carbonate catalyst (1.1 mol). Then, 0.1 mol of 4-tert-butyl-2-oxosodium benzaldehyde (tert-butyl-2-oxosodium benzaldehyde) was added as a capping agent, and the reaction was continued for 2 h. After precipitation and washing, the mixture was vacuum dried at 120 °C for 24 h to obtain a polyarylether ketone copolymer (PAEK-CHO) with aldehyde-terminated groups. Using 200 mL of dichloromethane and methanol (volume ratio 3:1) as solvents, PAEK-CHO (1 mol) and 4',4-diaminodiphenyl sulfone (DDS) (2 mol) were added to a reaction vessel at a molar ratio of 1:2. Then, 1 mol of acetic acid was added as a catalyst, and the mixture was heated to 50 °C and kept at that temperature for 5 h. The system was then filtered after being precipitated with n-hexane and washed with cold methanol. Finally, it was vacuum dried for 24 h to obtain the end-capped modified curing agent.

[0047] Example 2 An adhesive for wet-peelable fabric is made of 40 parts epoxy resin, 40 parts modified epoxy resin, 15 parts curing agent, 10 parts accelerator, 15 parts filler and 20 parts solvent by weight. The epoxy resin is composed of bisphenol A type epoxy resin and phenoxy resin in a mass ratio of 5:2. The modified epoxy resin is polymethacrylate-based heptaepoxy POSS, where m is 200 and n is 5; The curing agent is the end-capping modified curing agent obtained in Example 1; The accelerator is composed of imidazole and dicyandiamide in a mass ratio of 10:1; The filler is composed of aluminum hydroxide and fumed silica in a mass ratio of 1:1. The solvent is composed of butanone and cyclohexanone in a 1:1 mass ratio. Preparation method of adhesive: Epoxy resin and curing agent are mixed at room temperature for 30 min to obtain resin A; modified epoxy resin and filler are stirred in a closed manner at room temperature for 30 min to obtain resin B; resin A and resin B are added to a dispersion mill, and then accelerator and solvent are added and stirred and diluted for 30 min to obtain the adhesive for wet peelable fabric. Preparation method of wet peelable fabric: The adhesive obtained above is preheated at 50°C for 10 min and then coated on the surface of PET release substrate. After drying at 130°C for 3 min, a film-like resin substrate is obtained. The film-like resin layer on the film-like resin substrate and the NS-230 type fabric carrier are hot-pressed together at a temperature of 180°C and a pressure of 0.7 MPa. After removing the release substrate, the wet peelable fabric is obtained.

[0048] Example 3 An adhesive for wet-peelable fabric was prepared according to the method described in Example 2; The raw materials are in the following proportions by weight: 35 parts epoxy resin, 40 parts modified epoxy resin, 10 parts curing agent, 15 parts accelerator, 10 parts filler and 15 parts solvent. The wet peelable fabric was prepared according to the method in Example 2.

[0049] Example 4 An adhesive for wet-peelable fabric was prepared according to the method described in Example 2; The raw materials are in the following proportions by weight: 40 parts epoxy resin, 40 parts modified epoxy resin, 15 parts curing agent, 10 parts accelerator, 15 parts filler and 20 parts solvent. The epoxy resin is bisphenol A epoxy resin; The wet peelable fabric was prepared according to the method in Example 2.

[0050] Example 5 An adhesive for wet-peelable fabric was prepared according to the method described in Example 2; The raw materials are in the following proportions by weight: 40 parts epoxy resin, 40 parts modified epoxy resin, 15 parts curing agent, 10 parts accelerator, 15 parts filler and 20 parts solvent. Epoxy resin is composed of phenoxy resin and bisphenol F epoxy resin in a 3:1 ratio; The wet peelable fabric was prepared according to the method in Example 2.

[0051] Example 6 The adhesive for wet-peelable fabric was prepared according to the method of Example 2; wherein the accelerator was composed of imidazole and dicyandiamide in a mass ratio of 9:2. The wet peelable fabric was prepared according to the method in Example 2.

[0052] Example 7 The adhesive for wet-peelable fabric was prepared according to Example 2; wherein the filler was a mixture of aluminum hydroxide and fumed silica in a mass ratio of 2:1. The wet peelable fabric was prepared according to the method in Example 2.

[0053] Example 8 The adhesive for wet-peelable fabric was prepared according to Example 2; wherein the filler was a mixture of alumina, fumed silica and titanium dioxide in a mass ratio of 2:1:1. The wet peelable fabric was prepared according to the method in Example 2.

[0054] Performance testing The performance of the wet peelable fabric obtained in the examples was tested. The surface of the cured composite material treated with only manual polishing process (instead of wet peelable fabric) was used as Comparative Example 1, and the dry peelable fabric (instead of wet peelable fabric, model NS230-105 dry peelable fabric produced by Jiangsu Aihe Composite Materials Co., Ltd.) was used as Comparative Example 2. The sample preparation process for single / double lap shear test is as follows: (1) Prepare epoxy prepreg. According to the national standard GB / T7124 for the thickness of shearing plate, stack the prepreg (unidirectional HS high temperature belt, model EH104 of Hengshen Company) to a thickness of 1.6mm±0.1mm and a size of 100mm wide and 250mm long. (2) Cutting Apply wet / dry peelable fabric of various sizes to the surface of the prepreg, use a mold to lay it up and vacuum it (vacuum degree not less than 0.1MPa), and make sure that the side with wet / dry peelable fabric is facing down to ensure a smooth surface during secondary bonding. (3) Co-curing was carried out according to the recommended curing process of peelable fabric at 180℃ / 2h; after curing, the temperature was naturally cooled to below 60℃, and the wet / dry peelable fabric was peeled off from the surface of the prepreg. (For Comparative Example 1 without peelable fabric, the prepreg and the control group with peelable fabric were cured under the same conditions, and finally, only manual polishing was used to treat the surface prepreg.) (4) Overlap the long sides of the prepreg by 12.5mm, one at a time, and then perform secondary bonding using an adhesive film (AHEP-2012H high-temperature adhesive film produced by Jiangsu Aihe Composite Materials Co., Ltd.); cut the adhesive film into strips 12.5mm wide and 250mm long (the actual length is adjusted according to the specific situation) and attach them to the overlapping position of the prepreg, and cure according to the adhesive film curing process; after curing, cut the prepreg to a width of 25mm to obtain A standard shearing board.

[0055] The room temperature shear strength of the composite material was tested according to GB / T 7124. The shear strength test results are shown in Table 1: Table 1. Shear strength test results of the examples and comparative examples.

[0056] As shown in Table 1, the secondary bonding performance of the carbon fiber composite material treated with the wet peelable fabric of this embodiment is superior to that of the comparative example. The surface treatment process of the carbon fiber composite material using the wet peelable fabric of this invention for secondary bonding is simple, and the treated surface has high uniformity, which can effectively replace surface treatment processes such as manual grinding and sandblasting.

[0057] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing an end-capped modified curing agent, characterized in that, Includes the following steps: The reactants, catalyst, and organic solvent are first mixed and reacted. Then, a capping agent is added and a second reaction is carried out to obtain a polyarylether ketone copolymer with aldehyde groups at the end. The reactants are 4,4-difluorobenzophenone, bisphenol A, and biphenyl; the capping agent is 4-tert-butyl-2-oxosodium benzaldehyde. The end-capped modified curing agent is obtained by second mixing the polyarylether ketone copolymer with aldehyde groups at the end, 4',4-diaminodiphenyl sulfone, catalyst and organic solvent, and then carrying out a third reaction.

2. The preparation method according to claim 1, characterized in that, In the first mixture, the molar ratio of 4,4-difluorobenzophenone, bisphenol A, and biphenyl is 1~1.05:0.6~0.65:0.4~0.45; The catalyst comprises anhydrous potassium carbonate; the molar amount of the catalyst is 1.1 to 1.12 times the total molar amount of bisphenol A and biphenyl hydroquinone.

3. The preparation method according to claim 1, characterized in that, The temperature of the first reaction is 170~190℃, and the holding time is 8~10h; The first reaction was carried out under a protective atmosphere.

4. The preparation method according to claim 1, characterized in that, The molar ratio of 4,4-difluorobenzophenone to the capping agent is 1~1.05:0.08~0.1; The temperature of the second reaction is the same as that of the first reaction, and the time of the second reaction is 1 to 2 hours.

5. The preparation method according to claim 1, characterized in that, In the second mixture, the molar ratio of the terminal aldehyde-containing polyarylether ketone copolymer to 4',4-diaminodiphenyl sulfone is 1:2; The catalyst includes acetic acid; the molar ratio of the terminal aldehyde-containing polyaryletherketone copolymer to the catalyst is 1:0.5~1; The temperature of the third reaction is 40~50℃, and the time is 4~5h.

6. The end-capping modified curing agent prepared by the preparation method according to any one of claims 1 to 5; The end-capping modified curing agent has the following structure: Where m is 20~50 and n is 1~3.

7. An adhesive for wet-peelable fabrics, characterized in that, By weight, it includes: 10-40 parts epoxy resin, 20-50 parts modified epoxy resin, 8-20 parts curing agent, 5-15 parts accelerator, 10-20 parts filler and 10-20 parts solvent; The modified epoxy resin is polymethyl methacrylate-based heptaepoxy POSS; The curing agent is the end-capping modified curing agent as described in claim 6.

8. The adhesive for wet-peelable fabric according to claim 7, characterized in that, The epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy epoxy resin and phenolic epoxy resin; The accelerator includes at least one of imidazole, dicyandiamide, pyromellitic anhydride, and methylhexahydrophthalic anhydride; The filler includes at least one of aluminum hydroxide, aluminum oxide, fumed silica and titanium dioxide; The solvent includes at least one of ethyl acetate, butyl acetate, butanone, toluene, and cyclohexanone.

9. The method for preparing the adhesive for wet-peelable fabric according to claim 7 or 8, characterized in that, Includes the following steps: Epoxy resin and curing agent are mixed to obtain resin A; The modified epoxy resin and filler were mixed to obtain resin B; The resin A, resin B, accelerator and solvent are mixed to obtain the adhesive for the wet peelable fabric.

10. A method for preparing a wet-peelable fabric, characterized in that, Includes the following steps: After preheating, the adhesive is coated onto the surface of the release substrate and dried to obtain a film-like resin matrix; the adhesive is the wet peelable fabric adhesive as described in claim 7 or 8 or the wet peelable fabric adhesive prepared by the preparation method described in claim 9. The membrane resin layer on the membrane resin matrix is ​​bonded to the fabric carrier, and after the release matrix is ​​removed, the wet peelable fabric is obtained.

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