High-adhesion and high-impact-resistance hydrophilic membrane treating agent, preparation method and application

Abstract

The invention provides a high-adhesion and high-impact-resistance type hydrophilic membrane treating agent, which is prepared from the following ingredients in parts by weight: 40 to 60 parts of epoxy-polyurethane composite emulsion, 10 to 20 parts of nanometer composite hydrophilic agents, 5 to 15 parts of adhesion promoters, 8 to 12 parts of impact resistance modifiers and 0.5 to 2 parts of wetting flatting agents. The high-adhesion and high-impact-resistance type hydrophilic membrane treating agent is good in adhesion, high in impact resistance, good in hydrophilicity and resistant to corrosion.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to a hydrophilic film treatment agent with high adhesion and high impact resistance, its preparation method, and its application in the surface treatment of metal substrates. Technical Background

[0002] Modern industry and consumer products impose multiple, stringent, and often seemingly contradictory comprehensive performance requirements on the surface treatment of metals (mainly aluminum, magnesium, zinc and their alloys, and also applicable to steel): (1) Good adhesion: Subsequent coatings (such as paint, powder coatings, adhesives) must adhere firmly to the substrate to avoid peeling, blistering or detachment under various stresses (such as temperature changes, moisture penetration, mechanical vibration), which would lead to the failure of the final product. This is crucial for automotive parts, electronic product housings, and structural components used outdoors for extended periods. (2) Excellent impact resistance: The film layer and its supporting coating system must possess toughness and energy absorption characteristics to withstand severe physical impacts (such as drops, collisions, and extrusions), point loads, or deformation impacts (such as battery pack trays being squeezed or housings being struck), ensuring that the coating will not crack or peel off from the substrate due to impact. This is critical for ensuring structural integrity, sealing, and long-term aesthetics. (3) Durable hydrophilicity: The surface needs to exhibit long-term and stable "hydrophilicity" (low water contact angle) so that it can quickly adsorb and spread water. The main functions include: enhanced corrosion resistance: The water vapor layer adsorbed by the hydrophilic film can theoretically isolate the air for a short time, forming a hydrated protective film (particularly significant for preventing white rust on light metals). More importantly, in subsequent cathodic electrodeposition (CED), it can allow the electrocoating liquid to quickly wet the surface, forming a more uniform, dense, and better-adhesive and corrosion-resistant electrocoating film. Anti-condensation / anti-frost: It can quickly guide condensate to spread evenly instead of agglomerating into water droplets, reducing the risk of coating cracking caused by freezing stress (important for refrigeration components such as heat exchangers and air conditioning components). Easy to clean: The hydrophilic film makes it easy for water to spread and wash away dirt. Special functional applications: such as water-sensitive reactions (electrochemical, catalytic, etc.). (4) Environmental friendliness and process adaptability: Regulations are becoming stricter, forcing traditional chromium-containing (Cr) 6+ Highly toxic or heavy metal-containing coating technologies (such as zinc phosphating) are being phased out rapidly, and chromium-free, low-heavy-metal, low-energy-consumption, and environmentally friendly alternatives are the core demand. (5) Process simplification and compatibility: It needs to be highly compatible with existing mainstream coating processes (especially highly automated CED lines), with a wide operating window (temperature, time, pH), stable and reliable, and conducive to mass production. (6) Pretreatment requirements for substrates (such as degreasing, degreasing, and oxide film removal) need to be friendly and efficient. (7) Cost and efficiency: It needs to have competitive overall costs, simple processing steps, and short processing time.

[0003] The bottlenecks of traditional phosphating agents for metal surface treatment are as follows: (1) Chromium phosphating agents: provide excellent adhesion, corrosion resistance and certain adhesion, but Cr 6+ Highly toxic and carcinogenic, facing strict bans and environmental pressure. (2) Zinc-based phosphating agents: Crystalline film provides mechanical interlocking force and corrosion resistance, providing basic guarantee for adhesion and impact resistance, but has high roughness (affecting the smoothness of spraying and making it difficult to use directly on exposed decorative surfaces), relatively large film weight, film formation process requires temperature control, usually does not exhibit hydrophilicity (may be hydrophobic), and the processing contains a large amount of phosphorus, nickel, etc., which has an environmental burden. The impact absorption capacity of zinc-based films is limited. (3) Iron-based phosphating agents: More environmentally friendly, thinner film, can provide better adhesion and certain hydrophilicity, but usually the film layer is softer, has more pores, and generally has weaker impact resistance, making it difficult to meet the needs of high-energy impact, and the structure of the film does not provide sufficient support for the durability of hydrophilicity.

[0004] Chromium-free zirconium salt / organosilane treatment is a mainstream environmentally friendly alternative technology. It can form very thin chemical conversion films (nanoscale), providing good adhesion (chemical bonding) and a certain degree of corrosion resistance. Hydrophilicity can generally be achieved by adjusting the silane composition. However, the extremely thin organosilane films have limited protection against strong impacts. Under high-energy impacts, the film itself or the film / substrate interface is prone to fracture or failure. Single silane / zirconium salt systems have shortcomings in toughness and mechanical protection; moreover, the hydrophilicity of silanes relies on silanol groups, and their stability (especially under aging, humid heat, or abrasion conditions) is challenging, potentially leading to a degradation of hydrophilic properties.

[0005] Currently, it is difficult to balance the following properties in the overall performance of metal surface treatment:

[0006] (1) Adhesion and impact resistance: The membrane often needs to have strong chemical bonding and a dense structure, as well as certain mechanical buffering and toughness. (2) Impact resistance and hydrophilicity: High impact requires a dense and tough membrane layer, but this may inhibit the formation of effective hydrophilic surface microstructures. Overly dense membranes (such as some ceramicized membranes) are not easy to achieve ideal hydrophilicity. (3) Process stability and compatibility: The solution stability of different technical systems, compatibility with different substrates (especially castings), and sensitivity to changes in water quality and pretreatment need to be overcome.

[0007] To meet increasingly stringent environmental regulations (chromium-free, low-phosphorus / phosphorus-free, non-toxic), a new metal surface treatment technology is being developed. The key challenge is how to significantly improve the toughness / energy absorption capacity of the ultra-thin conversion film while forming it, and ensure that the generated film has excellent substrate adhesion, long-term stable hydrophilicity, excellent corrosion resistance, and good compatibility with existing mainstream coating processes (especially electrophoresis CED) and production stability. Summary of the Invention

[0008] This invention provides a high-adhesion, high-impact hydrophilic film treatment agent, the components of which, by weight, include the following: 40-60 parts of epoxy-polyurethane composite emulsion, 10-20 parts of nano-composite hydrophilic agent, 5-15 parts of adhesion promoter, 8-12 parts of impact modifier, and 0.5-2 parts of wetting and leveling agent.

[0009] The preparation method of the epoxy-polyurethane composite emulsion is as follows:

[0010] (1) Preparation of prepolymer

[0011] Raw material ratio: 100 parts of polytetrahydrofuran ether diol with a molecular weight of 1000-2000, 30-40 parts of diisocyanate, 15-20 parts of epoxy resin, 0.05-0.1 parts of catalyst, and 20-30 parts of solvent. The preparation method is as follows: Add polytetrahydrofuran ether diol to a reactor, dehydrate under vacuum at 100-110℃ for 2-6 hours, cool to 60-70℃, purge with nitrogen for protection, add diisocyanate and catalyst, and stir for 1-2 hours; add epoxy resin, heat to 80-85℃ and react for 2-3 hours to obtain epoxy-polyurethane prepolymer; add acetone to adjust the viscosity to 1000-2000 mPa•s.

[0012] (2) Hydrophilic modification and neutralization:

[0013] Raw materials: the prepolymer prepared in step (1), 8-12 parts of hydrophilic chain extender, and 6-9 parts of neutralizer. The preparation method is as follows: cool the prepolymer to 50-60℃, add the hydrophilic chain extender, and react at 80-85℃ for 2-3 hours (the NCO content is reduced to the theoretical value); cool to 40-50℃, add the neutralizer, and stir at high speed for 30-40 minutes, with the degree of neutralization controlled at 90%-100%.

[0014] (3) Emulsification and aqueous chain extension:

[0015] Raw materials: neutralized prepolymer, 150-200 parts deionized water, 2-3 parts aqueous chain extender. Preparation method is as follows: under high-speed shearing conditions, deionized water is added dropwise to the prepolymer for 30-60 minutes to form a primary emulsion; continue shearing for 15-20 minutes, slowly add the aqueous chain extender, and react at 50-60℃ for 1-2 hours to obtain a stable emulsion.

[0016] (4) Post-processing:

[0017] The above stable emulsion is distilled under reduced pressure at 40-50℃ and a vacuum degree ≤-0.09MPa to remove acetone, and then filtered through a 100-200 mesh filter to obtain an epoxy-polyurethane composite emulsion with a solid content of 30%-40%.

[0018] The nanocomposite hydrophilic agent is made of nano-SiO2@polyacrylic acid core-shell particles and polyethylene glycol methyl ether acrylate, with a compound weight ratio of (1-2):1. The carboxyl groups (strongly hydrophilic) of the nano-SiO2@polyacrylic acid core-shell particles and the ether bonds (moderately hydrophilic) of polyethylene glycol methyl ether acrylate contribute to the hydrophilic properties. Excessive use of core-shell particles (>2:1) leads to an excessively high carboxyl group density and excessive swelling of the system; insufficient use of core-shell particles (<1:1) results in a high proportion of PEG segments, insufficient hydrophilic group density, and weakened hydrophilicity. The (1-2:1) ratio ensures a moderate total hydrophilic group density, guaranteeing strong interaction with water (low contact angle) while avoiding structural damage due to excessive water absorption.

[0019] The preparation method of the nano-SiO2@polyacrylic acid core-shell particles is as follows:

[0020] (1) Preparation of SiO2 nanonuclei: The sol-gel method was used to mix tetraethyl orthosilicate (TEOS), ethanol and deionized water in proportion, and ammonia water was added dropwise as a catalyst. The mixture was stirred at 30-50℃ for 2-4 hours to hydrolyze and condense to generate SiO2 nanoparticles. After centrifugation, washing and drying, the nanoparticles were ready for use.

[0021] (2) SiO2 surface modification: SiO2 nanoparticles were dispersed in ethanol, and γ-methacryloxypropyltrimethoxysilane (KH570) was added. The mixture was refluxed at 60-80℃ for 4-6 h to graft double bond groups (m-SiO2) onto the surface of SiO2. The mixture was then centrifuged, washed and dried.

[0022] (3) Core-shell particle polymerization: Using water as the medium, add m-SiO2, acrylic acid (AA) monomer, sodium dodecyl sulfate (SDS) emulsifier, disperse by ultrasonication and then purge with nitrogen to remove oxygen; add potassium persulfate (KPS) initiator, stir and react at 70-80℃ for 3-5h, cool and centrifuge, wash with deionized water and ethanol alternately, and vacuum dry to obtain SiO2@polyacrylic acid core-shell particles.

[0023] In step (1), the molar ratio of tetraethyl orthosilicate to ethanol is 1:(5-7), with ethanol in excess to promote dissolution and control the reaction rate; the molar ratio of tetraethyl orthosilicate to water in step (1) is 1:(7-10), with water in excess to ensure complete hydrolysis; the amount of ammonia (NH3·H2O) catalyst is expressed as a molar ratio or volume fraction relative to tetraethyl orthosilicate (TEOS). Typical amounts are: a molar ratio of TEOS to ammonia of 1:0.1-0.5 (based on NH3); if 25%-28% concentrated ammonia is used, the volume is usually 1%-5% of the total volume of the reaction system, or 1-3 mL of concentrated ammonia per 10 mL of TEOS.

[0024] In step (2), the amount of γ-methacryloyloxypropyltrimethoxysilane (KH570) used is 2-5% of the mass of SiO2 nanoparticles; the amount of solvent ethanol used is 5-15 times the mass of SiO2 nanoparticles.

[0025] In step (3), the weight ratio of m-SiO2 to acrylic acid (AA) monomer is 1:(2-5), the amount of sodium dodecyl sulfate (SDS) emulsifier is 1-5 wt% of acrylic acid (AA) monomer, and the amount of potassium persulfate is 0.5-1.5 wt% of acrylic acid (AA) monomer.

[0026] The adhesion promoter is γ-aminopropyltriethoxysilane (KH550) and zirconium phosphate pre-reactant, and the preparation method of the pre-reactant is as follows:

[0027] (1) Raw material preparation: Weigh γ-aminopropyltriethoxysilane and zirconium phosphate according to the mass fraction;

[0028] (2) Solvent and hydrolysis: Add γ-aminopropyltriethoxysilane to anhydrous ethanol, stir to disperse, add a small amount of deionized water and a trace amount of hydrochloric acid (to adjust the pH to 3-5), stir at room temperature for 30-60 minutes to partially hydrolyze γ-aminopropyltriethoxysilane to generate silanol (Si-OH).

[0029] (3) Dispersion and mixing: Zirconium phosphate was added to the above hydrolysate and ultrasonically dispersed for 30 minutes until a uniform suspension was formed. After partially hydrolyzing γ-aminopropyltriethoxysilane to generate Si-OH, zirconium phosphate was added to react with it in a dehydration condensation reaction, and finally a hydrolysate suspension was formed.

[0030] (4) Reaction conditions: Heat to 60-80℃ and reflux for 2-4 hours to promote the dehydration condensation reaction between silanol groups and zirconium phosphate surface hydroxyl groups (or active sites).

[0031] (5) Post-processing: After the reaction is completed, the solid is separated by vacuum filtration, washed 2-3 times with anhydrous ethanol, and dried under vacuum at 80-100℃ for 4-6 hours to obtain the pre-reactant.

[0032] In step (1), the weight ratio of γ-aminopropyltriethoxysilane to zirconium phosphate is (1-2):1. If too much zirconium phosphate is used, the performance of the accelerator will be significantly reduced, mainly manifested as: reduced adhesion to the substrate and organic resin, poor dispersibility in the organic system and easy agglomeration, decreased mechanical properties such as tensile strength and impact strength of the coating or composite material, and poor storage stability of the system, or even gelation. The main reason is that γ-aminopropyltriethoxysilane, as a silane coupling agent, needs to react with zirconium phosphate in an appropriate ratio. Through the condensation of its silanol groups with the hydroxyl groups on the surface of zirconium phosphate, a coupling structure is formed. At the same time, the amino groups at the end of the silane can interact with the organic resin, thereby enhancing the interfacial bonding. When zirconium phosphate is in excess, the silane coupling agent is relatively insufficient and cannot fully modify the surface of zirconium phosphate. The unreacted zirconium phosphate is prone to agglomeration due to its high surface energy, resulting in difficulty in dispersion; at the same time, the effective chemical coupling sites at the interface are reduced, weakening the bonding force between materials, ultimately causing a decrease in adhesion and overall performance.

[0033] In step (2), the ratio of ethanol to γ-aminopropyltriethoxysilane is 1:1-2, and the amount of water is 1-2 times the molar amount of γ-aminopropyltriethoxysilane.

[0034] The disadvantages of directly blending zirconium phosphate with γ-aminopropyltriethoxysilane instead of preparing a pre-reactant are as follows:

[0035] (1) The ethoxy group of KH550 is difficult to fully hydrolyze into silanol (-Si-OH) under solvent-free / water-free conditions. The covalent bond (-Si-OP-) with the hydroxyl group (-OH) on the zirconium phosphate surface is limited. It mainly binds to the acidic hydroxyl group on the zirconium phosphate surface through hydrogen bonding or electrostatic attraction of the amino group (-NH2). The interfacial binding force is weaker than that of pre-hydrolysis modification.

[0036] (2) If the system contains trace amounts of water or is damp, the silanol generated by the hydrolysis of KH550 is prone to intermolecular condensation (-Si-O-Si-), which may bridge the zirconium phosphate particles and cause agglomeration, reducing the dispersion uniformity.

[0037] (3) Excessive free KH550 may have a plasticizing effect, reducing the rigidity of the material; affecting the storage stability or reactivity of the system.

[0038] The impact modifier is preferably hydrogenated nitrile rubber microparticles with a particle size of 100-200 nm and a molecular weight of 10. 5 -10 6 .

[0039] The wetting and leveling agent is preferably an acetylenic diol compound.

[0040] The preparation method of the high-adhesion, high-impact hydrophilic film treatment agent of the present invention comprises the following steps in sequence:

[0041] (a) Emulsify the epoxy-polyurethane composite emulsion and the nano-composite hydrophilic agent in a high-speed shear emulsifier at a speed of 8000-9000 rpm for 30-40 min.

[0042] (b) Add adhesion promoter and stir at a constant temperature of 55-60℃ for 1-2 hours;

[0043] (c) Add the impact modifier and wetting leveling agent in sequence, and stir at low speed at 40-50℃ for 20-30 minutes;

[0044] (d) Add water, adjust the solid content to 15-20%, and filter to obtain the finished product.

[0045] The application method of the high adhesion and high impact resistance hydrophilic film treatment agent of the present invention is as follows: after degreasing and washing the metal substrate, immerse or spray it with the hydrophilic film treatment agent of the present invention (temperature 25-40℃, time 60-120s), and bake it at 80-100℃ for 5-8 minutes to form a film.

[0046] The formulation principle of the high adhesion and high impact resistance hydrophilic film treatment agent of the present invention is as follows:

[0047] Through multi-component synergistic compounding, an environmentally friendly metal salt (zirconium salt) is used as the base film component to construct a corrosion-resistant film skeleton structure. Modified acrylic resin, polyurethane emulsion, and other organic toughening / adhesive agents are introduced to improve toughness by hindering the absorption of impact energy through plastic deformation and microcracks. Simultaneously, functional groups (-OH, -COOH, etc.) form chemical bonds with the substrate and form an interpenetrating network structure or strong interactions with the metal salt component to enhance film cohesion and adhesion. Hydrophilic monomers are introduced through polymer chains to optimize the density of hydrophilic groups, ensuring abundant and durable hydrophilic functional groups within the film. Hydrophilic modifiers are added to promote rapid and uniform film formation and expose surface hydrophilic groups, improving pore sealing to compensate for microporous defects in the metal salt film. Crosslinking promoters / corrosion inhibitors are added to optimize the film-forming chemical reaction and corrosion resistance, ultimately forming a film with high adhesion, high impact resistance, and durable hydrophilicity.

[0048] The beneficial effects of the high adhesion and high impact resistance hydrophilic film treatment agent of the present invention are as follows: good adhesion, up to grade 0 (GB / T9286 cross-cut test), high impact resistance, impact resistance >80cm·kg (ASTM D2794 standard), good hydrophilicity, water contact angle ≤15° (JC / T 2329-2015 hydrophilicity test), corrosion resistance, salt spray resistance >500h (GB / T10125 neutral salt spray test). Detailed Implementation

[0049] The hydrogenated nitrile butadiene rubber microparticles in the examples were purchased from Jiangsu Shengao Chemical Technology Co., Ltd.

[0050] The preparation method of the epoxy-polyurethane composite emulsion in the examples is as follows (all parts by weight):

[0051] (1) Preparation of prepolymer

[0052] Raw material ratio: 100 parts of polytetrahydrofuran ether diol with a molecular weight of 1000, 35 parts of toluene diisocyanate, 17.5 parts of epoxy resin, 0.075 parts of dibutyltin dilaurate, and 25 parts of acetone. The preparation method is as follows: Add polytetrahydrofuran ether diol to a reactor, dehydrate under vacuum at 110℃ for 2 hours, cool to 65℃, purge with nitrogen for protection, add toluene diisocyanate and dibutyltin dilaurate, and stir for 2 hours; add epoxy resin, heat to 85℃ and react for 2 hours to obtain epoxy-polyurethane prepolymer; add acetone to adjust the viscosity to 1500-1600 mPa•s.

[0053] (2) Hydrophilic modification and neutralization:

[0054] Raw materials: 10 parts of the prepolymer prepared in step (1), 10 parts of dimethylolpropionic acid, and 8 parts of triethylamine. The preparation method is as follows: cool the prepolymer to 55°C, add dimethylolpropionic acid, and react at 85°C for 3 hours (the NCO content is reduced to the theoretical value); cool to 45°C, add triethylamine, stir at high speed for 30 minutes, and control the degree of neutralization at 90%-100%.

[0055] (3) Emulsification and aqueous chain extension:

[0056] Raw materials: neutralized prepolymer, 175 parts deionized water, 2.5 parts ethylenediamine. The preparation method is as follows: under high-speed shearing conditions, deionized water is added dropwise to the prepolymer for 40 minutes to form a primary emulsion; shearing continues for 20 minutes, and ethylenediamine is slowly added dropwise. The reaction is carried out at 55°C for 2 hours to obtain a stable emulsion.

[0057] (4) Post-processing:

[0058] The above stable emulsion was distilled under reduced pressure at 45℃ and a vacuum degree ≤ -0.09MPa to remove acetone, and then filtered through a 100-200 mesh filter to obtain the epoxy-polyurethane composite emulsion.

[0059] The preparation method of nano-SiO2@polyacrylic acid core-shell particles in the examples is as follows:

[0060] (1) Preparation of SiO2 nanonuclei: The sol-gel method was used to mix tetraethyl orthosilicate (TEOS), ethanol, and deionized water in a ratio of tetraethyl orthosilicate:ethanol:deionized water = 1:6:8. Ammonia was added dropwise as a catalyst, and the mixture was stirred at 40°C for 3 hours to hydrolyze and condense to generate SiO2 nanoparticles. After centrifugation, washing, and drying, the nanoparticles were ready for use. The molar ratio of TEOS to ammonia was 1:0.1 (calculated as NH3).

[0061] (2) SiO2 surface modification: SiO2 nanoparticles were dispersed in ethanol, and γ-methacryloxypropyltrimethoxysilane (KH570) was added. The mixture was refluxed at 60-80℃ for 5 h to graft double bond groups (m-SiO2) onto the surface of SiO2. The mixture was then centrifuged, washed and dried. The amount of γ-methacryloxypropyltrimethoxysilane (KH570) was 3% of the mass of the SiO2 nanoparticles. The amount of ethanol used as solvent was 10 times that of the silica particles.

[0062] (3) Core-shell particle polymerization: Using water as a medium, m-SiO2, acrylic acid (AA) monomer, and sodium dodecyl sulfate (SDS) emulsifier are added, ultrasonically dispersed, and then nitrogen gas is purged to remove oxygen; potassium persulfate (KPS) initiator is added, and the mixture is stirred at 70-80℃ for 4 hours. After cooling, it is centrifuged and washed alternately with deionized water and ethanol, and then vacuum dried to obtain SiO2@polyacrylic acid core-shell particles; wherein the weight ratio of m-SiO2 to acrylic acid (AA) monomer is 1:3; the amount of sodium dodecyl sulfate (SDS) emulsifier is 2.55% of the acrylic acid (AA) monomer, the amount of potassium persulfate is 1% of the acrylic acid (AA) monomer, and the amount of water is 10 times the mass of the total solids (m-SiO2+AA).

[0063] The preparation method of the pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate in the examples is as follows:

[0064] (1) Raw material preparation: Weigh 8 parts of γ-aminopropyltriethoxysilane and 4 parts of zirconium phosphate by mass.

[0065] (2) Solvent and hydrolysis: Add γ-aminopropyltriethoxysilane to anhydrous ethanol, with the ratio of ethanol to γ-aminopropyltriethoxysilane being 1:1. Stir and disperse, then add a small amount of deionized water (the amount of water is twice the molar amount of γ-aminopropyltriethoxysilane) and a trace amount of hydrochloric acid (to adjust the pH to 4). Stir at room temperature for 40 minutes to partially hydrolyze γ-aminopropyltriethoxysilane to generate silanol groups (Si-OH), thus obtaining the hydrolysate.

[0066] (3) Dispersion and mixing: Add zirconium phosphate to the above hydrolysate and ultrasonically disperse for 30 minutes until a uniform suspension is formed.

[0067] (4) Reaction conditions: Heat to 70°C and reflux for 3 hours to promote the dehydration condensation reaction between silanol groups and zirconium phosphate surface hydroxyl groups (or active sites).

[0068] (5) Post-processing: After the reaction is completed, the solid is separated by vacuum filtration, washed three times with anhydrous ethanol, and dried under vacuum at 90°C for 5 hours to obtain the pre-reactant.

[0069] Example 1

[0070] Take 50 parts of epoxy-polyurethane composite emulsion, add 6 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 30min, add 10 parts of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactant, stir at 60℃ for 1h, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0071] The 6061 aluminum alloy substrate was treated with the film treatment agent obtained in Example 1, and the immersion treatment lasted for 90 seconds (35°C), followed by baking at 90°C for 6 minutes. The results showed: cross-cut adhesion grade 0, high impact resistance, impact resistance of 82 cm•kg (ASTM D2794 standard), water contact angle of 12°, corrosion resistance, and no blistering after 504 hours of salt spray corrosion resistance (GB / T10125 neutral salt spray test).

[0072] Comparative Example 1

[0073] Based on Example 1, without the addition of a nanocomposite hydrophilic agent, the specific preparation method is as follows:

[0074] Take 50 parts of epoxy-polyurethane composite emulsion, add 10 parts of the pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate, stir at 60℃ for 1 hour, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylenic diol, stir at 40℃ for 20 minutes, add deionized water to adjust the solid content to 18%, and filter.

[0075] The 6061 aluminum alloy substrate was treated by immersion for 90 seconds (35℃) and then baked at 90℃ for 6 minutes. In Comparative Example 1, because no nano-composite hydrophilic agent (nano SiO2@polyacrylic acid core-shell particles, polyethylene glycol methyl ether acrylate) was added, the adhesion of the 6061 aluminum alloy experimental plate decreased to level 2 (adhesion levels are divided into 0, 1, 2, 3, 4, and 5; level 0 is the best, and level 5 is the worst), and the water contact angle also increased significantly (water contact angle 35°), indicating a decrease in water affinity.

[0076] Comparative Example 2

[0077] Comparative Example 2, based on Example 1, did not add the pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate. The specific preparation method is as follows: Take 50 parts of epoxy-polyurethane composite emulsion, add 6 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), and emulsify at 8000rpm for 30min. Add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0078] The same treatment was applied to the 6061 aluminum alloy substrate, followed by immersion treatment for 90 seconds (35℃) and baking at 90℃ for 6 minutes.

[0079] Comparative Example 2, without the addition of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactants, showed that the salt spray corrosion resistance time of the 6061 aluminum alloy experimental plate was also significantly reduced (no blistering phenomenon after 340h).

[0080] Comparative Example 3

[0081] Take 50 parts of epoxy-polyurethane composite emulsion, add 6 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 30min, add 10 parts of a mixture of γ-aminopropyltriethoxysilane and zirconium phosphate (physically dry-mix γ-aminopropyltriethoxysilane and zirconium phosphate at a weight ratio of 2:1), stir at 60℃ for 1h, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0082] The 6061 aluminum alloy substrate was treated with immersion treatment for 90 seconds (35℃) and baked at 90℃ for 6 minutes. The results showed: cross-cut adhesion grade 2, impact resistance 70 cm•kg (ASTM D2794 standard), water contact angle 14°, corrosion resistance, and no blistering after 401 hours of salt spray corrosion resistance (GB / T10125 neutral salt spray test).

[0083] Comparative Example 4

[0084] Take 50 parts of epoxy-polyurethane composite emulsion, add 4 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 6 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 30min, add 10 parts of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactant, stir at 60℃ for 1h, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0085] The 6061 aluminum alloy substrate was treated with immersion for 90 seconds (35℃) and then baked at 90℃ for 6 minutes. The results showed: cross-cut adhesion grade 2, impact resistance 71 cm•kg (ASTM D2794 standard), water contact angle 23°, corrosion resistance, and no blistering after 504 hours of salt spray test (GB / T10125 neutral salt spray test).

[0086] Example 2

[0087] Take 50 parts of epoxy-polyurethane composite emulsion, add 8 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 30min, add 10 parts of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactant, stir at 60℃ for 1h, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0088] The 6061 aluminum alloy substrate was treated with immersion treatment for 90 seconds (35℃) and baked at 90℃ for 6 minutes. The results showed: cross-cut adhesion grade 0, high impact resistance, impact resistance of 85 cm•kg (ASTM D2794 standard), water contact angle of 14°, corrosion resistance, and no blistering after 513 hours of salt spray corrosion resistance (GB / T10125 neutral salt spray test).

[0089] Example 3:

[0090] Take 50 parts of epoxy-polyurethane composite emulsion, add 6 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 30min, add 13 parts of the pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate, stir at 60℃ for 1h, add 10 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1.5 parts of ethoxyacetylene glycol, stir at 40℃ for 20min, add deionized water to adjust the solid content to 18%, and filter.

[0091] The 6061 aluminum alloy substrate was treated with immersion treatment for 90 seconds (35℃) and baked at 90℃ for 6 minutes. The results showed: cross-cut adhesion grade 0, high impact resistance, impact resistance of 80 cm•kg (ASTM D2794 standard), water contact angle of 12°, corrosion resistance, and no blistering after 504 hours of salt spray corrosion resistance (GB / T10125 neutral salt spray test).

[0092] Example 4

[0093] Take 50 parts of epoxy-polyurethane composite emulsion, add 8 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 5 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 8000rpm for 25min, add 12 parts of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactant, stir at 55℃ for 1.5h, add 12 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 2 parts of ethoxyacetylene glycol, stir at 45℃ for 15min, add deionized water to adjust the solid content to 20%, and filter. Treat 7075 aluminum alloy substrate, immersion treatment for 80s (40℃), bake at 100℃ for 5min. The results are: cross-cut adhesion grade 0, impact resistance 95cm•kg (ASTM D2794 standard), water contact angle 10°, salt spray resistance 600h without blistering (GB / T10125 neutral salt spray test).

[0094] Example 5

[0095] Take 50 parts of epoxy-polyurethane composite emulsion, add 7 parts of nano-SiO2@polyacrylic acid core-shell particles (particle size 50nm) and 4 parts of polyethylene glycol methyl ether acrylate (molecular weight 500), emulsify at 9000rpm for 35min, add 8 parts of γ-aminopropyltriethoxysilane and zirconium phosphate pre-reactant, stir at 65℃ for 1h, add 8 parts of hydrogenated nitrile rubber microparticles (particle size 150nm) and 1 part of ethoxyacetylene glycol, stir at 35℃ for 25min. Add deionized water to adjust the solid content to 16%, filter. Treat 2024 aluminum alloy substrate, immersion treatment for 100s (30℃), bake at 80℃ for 8min. The results are: cross-cut adhesion grade 0, impact resistance 78cm•kg (ASTM D2794 standard), water contact angle 15°, salt spray resistance 500h without blistering (GB / T10125 neutral salt spray test).

[0096] The surface film treatment technology of this invention, which features high adhesion and high impact resistance, has significant advantages: It introduces a nano-composite hydrophilic agent, resulting in a dense cross-linking density with the coating and reducing its water contact angle; it adds an adhesion promoter (a pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate), thereby enhancing the coating's adhesion; while traditional silane-based treatment agents typically have an impact resistance of less than 50 cm·kg, this film treatment agent breaks through the original technical performance bottleneck, increasing the impact resistance to 80 cm·kg; it is a multifunctional and environmentally friendly product that simultaneously achieves high adhesion, high impact resistance, and superhydrophilicity.

[0097] The test methods for the above embodiments and comparative performance are as follows:

[0098] (1) GB / T9286 Cross-cut adhesion test:

[0099] Cutting tool: Multi-blade cutting tool, the grid spacing is selected according to the coating thickness (1mm for ≤60μm, 2mm for >60μm).

[0100] Stroke depth: Penetrating the coating to the substrate;

[0101] Post-grid processing: Use a soft brush to gently sweep along both directions of the grid;

[0102] Assessment: The cut edges are completely smooth, with no chips missing.

[0103] (2) ASTM D2794 Impact Resistance Test:

[0104] Instrument: Drop hammer impact tester (positive / negative impact mode);

[0105] Impact head: 1 / 2 inch (12.7 mm) in diameter;

[0106] Impact energy: calculated by the product of the mass and height of the falling hammer (e.g., 1kg falling 80cm, or 2kg falling 40cm, etc.); Post-impact inspection: the coating has no cracks, peeling, or adhesion failure.

[0107] (3) JC / T 2329-2015 Hydrophilicity Test (Water Contact Angle Test):

[0108] Environment: Temperature 23±2℃, relative humidity 50±5%;

[0109] Sample: The coating is cured to full dryness as specified, and the thickness meets the product requirements;

[0110] Test solution: deionized water, droplet volume 5μL±1μL;

[0111] Method: Sessile drop method, measurements were taken within 10 seconds after the droplet stabilized, and the average value was taken from at least 5 different locations.

[0112] (4) GB / T10125 Neutral Salt Spray Test:

[0113] Salt solution: 5%±1% sodium chloride aqueous solution, pH 6.5-7.2 (at 35℃);

[0114] Salt spray deposition rate: 1.0-2.0 mL / h × d㎡;

[0115] Test chamber temperature: 35±2℃, saturator temperature: 47±2℃;

[0116] Spraying method: Continuous spraying;

[0117] Sample placement: at an angle of 15°-30° to the vertical direction, without obstruction.

[0118] The above examples are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention.

Claims

1. A high-adhesion, high-impact hydrophilic film treatment agent, characterized in that, By weight, it includes the following components: 40-60 parts epoxy-polyurethane composite emulsion, 10-20 parts nano-composite hydrophilic agent, 5-15 parts adhesion promoter, 8-12 parts impact modifier, and 0.5-2 parts wetting and leveling agent.

2. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 1, characterized in that, The preparation method of the epoxy-polyurethane composite emulsion is as follows: (1) Preparation of prepolymer By weight, take 100 parts of polytetrahydrofuran ether diol with a molecular weight of 1000-2000, 30-40 parts of diisocyanate, 15-20 parts of epoxy resin, 0.05-0.1 parts of catalyst, and 20-30 parts of solvent. The preparation method is as follows: Add polytetrahydrofuran ether diol to a reactor, dehydrate under vacuum at 100-110℃ for 2-6 hours, cool to 60-70℃, purge with nitrogen for protection, add diisocyanate and catalyst, and stir for 1-2 hours; add epoxy resin, heat to 80-85℃ and react for 2-3 hours to obtain epoxy-polyurethane prepolymer; add acetone to adjust the viscosity to 1000-2000 mPa•s. (2) Hydrophilic modification and neutralization: Raw materials: the prepolymer prepared in step (1), 8-12 parts of hydrophilic chain extender, and 6-9 parts of neutralizer. The preparation method is as follows: cool the prepolymer to 50-60℃, add the hydrophilic chain extender, react at 80-85℃ for 2-3 hours, cool to 40-50℃, add the neutralizer, stir at high speed for 30-40 minutes to obtain the neutralized prepolymer, and control the degree of neutralization at 95%. (3) Emulsification and aqueous chain extension: Raw materials: the neutralized prepolymer prepared in step (2), 175 parts of deionized water, and 2-3 parts of aqueous chain extender. The preparation method is as follows: under high-speed shearing conditions, deionized water is added dropwise to the neutralized prepolymer for 30-60 min, shearing is continued for 15-20 min, aqueous chain extender is added dropwise, and the reaction is carried out at 50-60℃ for 1-2 h to obtain a stable emulsion. (4) Post-processing: The above stabilized emulsion is subjected to vacuum distillation at 40-50℃ and a vacuum degree ≤-0.09MPa to remove acetone, and then filtered through a 100-200 mesh filter to obtain an epoxy-polyurethane composite emulsion with a solid content of 30%-40%.

3. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 1, characterized in that, The nanocomposite hydrophilic agent is made of nano SiO2@polyacrylic acid core-shell particles and polyethylene glycol methyl ether acrylate, with a compound weight ratio of (1-2):

1.

4. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 3, characterized in that, The preparation method of the nano-SiO2@polyacrylic acid core-shell particles is as follows: (1) Preparation of SiO2 nanonuclei: The sol-gel method was used to mix tetraethyl orthosilicate, ethanol and deionized water in proportion, and ammonia water was added dropwise as a catalyst. The mixture was stirred at 30-50℃ for 2-4 hours to hydrolyze and condense to generate SiO2 nanoparticles. After centrifugation, washing and drying, the nanoparticles were ready for use. (2) SiO2 surface modification: SiO2 nanoparticles were dispersed in ethanol, γ-methacryloxypropyltrimethoxysilane was added, and the mixture was refluxed at 60-80℃ for 4-6h to form m-SiO2 by grafting double bond groups on the surface of SiO2. The mixture was then centrifuged, washed and dried. (3) Core-shell particle polymerization: Using water as a medium, add m-SiO2, acrylic acid monomer, sodium dodecyl sulfate emulsifier, disperse by ultrasonication and then remove oxygen by nitrogen gas; add potassium persulfate initiator, stir and react at 70-80℃ for 3-5h, cool and centrifuge, wash with deionized water and ethanol alternately, and vacuum dry to obtain SiO2@polyacrylic acid core-shell particles.

5. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 4, characterized in that, In step (1), the molar ratio of tetraethyl orthosilicate to ethanol is 1:(5-7); in step (1), the molar ratio of tetraethyl orthosilicate to water is 1:(7-10).

6. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 4, characterized in that, In step (2), the amount of γ-methacryloxypropyltrimethoxysilane used is 2-5% of the mass of SiO2 nanoparticles; the amount of solvent ethanol used is 5-15 times the mass of SiO2 nanoparticles; in step (3), the weight ratio of m-SiO2 to acrylic monomer is 1:(2-5): the amount of sodium dodecyl sulfate emulsifier used is 1-5% of the acrylic monomer, and the amount of potassium persulfate used is 0.5-1.5% of the acrylic monomer.

7. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 1, characterized in that, The adhesion promoter is a pre-reactant of γ-aminopropyltriethoxysilane and zirconium phosphate, with a weight ratio of γ-aminopropyltriethoxysilane to zirconium phosphate of (1-2):

1.

8. The high-adhesion, high-impact hydrophilic film treatment agent according to claim 7, characterized in that, The pre-reactant is prepared as follows: (1) Raw material preparation: Weigh γ-aminopropyltriethoxysilane and zirconium phosphate according to the mass fraction; (2) Solvent and hydrolysis: Add γ-aminopropyltriethoxysilane to anhydrous ethanol, stir to disperse, add a small amount of deionized water and a trace amount of hydrochloric acid to adjust the pH to 3-5, stir at room temperature for 30-60 minutes to form a hydrolysate; (3) Dispersion and mixing: Add zirconium phosphate to the above hydrolysate and ultrasonically disperse for 30 minutes until a uniform suspension is formed; (4) Reaction conditions: Heat to 60-80℃ and reflux with stirring for 2-4 hours; (5) Post-processing: After the reaction is completed, the solid is separated by vacuum filtration, washed 2-3 times with anhydrous ethanol, and dried under vacuum at 80-100℃ for 4-6 hours to obtain the pre-reactant.

9. The method for preparing the high-adhesion, high-impact hydrophilic film treatment agent according to claim 1, characterized in that, The steps are as follows: (a) Emulsify the epoxy-polyurethane composite emulsion and the nano-composite hydrophilic agent in a high-speed shear emulsifier at a speed of 8000-9000 rpm for 30-40 min. (b) Add adhesion promoter and stir at a constant temperature of 55-60℃ for 1-2 hours; (c) Add the impact modifier and wetting leveling agent in sequence, and stir at low speed at 40-50℃ for 20-30 minutes; (d) Add water, adjust the solid content to 15-20%, and filter to obtain the finished product.

10. The application of the high-adhesion, high-impact hydrophilic film treatment agent according to any one of claims 1-8 in metal surface treatment.