Two-part curing composition for treating metal surfaces, method for attaching a film on a metal surface, and surface structure

Abstract

The present invention provides a two-part curing composition for metal surface treatment, a method for attaching a film to a metal surface, and a surface structure. The two-part curing composition comprises 15-35 wt% liquid epoxy resin, 20-35 wt% curing agent for the epoxy resin, 5-15 wt% diluent, 10-25 wt% weight-reducing agent, and 5-20 wt% flame retardant. The two-part curing composition comprises Part A and Part B, where Part A contains the liquid epoxy resin and Part B contains the curing agent for the epoxy resin, and the diluent, weight-reducing agent, and flame retardant are present in one or both Parts A and B. When applied, the two-part curing composition for metal surface treatment has good open time and surface drying time, and exhibits very high bond strength and aging resistance to the treated metal surface. Use of the composition allows for convenient, simple, and quick attachment of a film to a metal surface (e.g., the surface of a vehicle body).

Description

[Technical Field]

[0001] The present invention relates to the technical field of metal surface treatment. Specifically, the present invention provides a two-part curing composition for metal surface treatment, a method for attaching a film on a metal surface, and a surface structure, which are particularly suitable for treating the surface of a vehicle body and attaching a film on the surface of a vehicle body. [Background technology]

[0002] During the manufacture and use of metal products (especially vehicles), graphic films are often attached to metal surfaces for purposes such as marking, warning, and advertising. The metal surface for attaching the graphic film should be flat and free of obvious defects such as holes, bumps, and depressions. To achieve a firm attachment of the graphic film to the metal surface, multiple surface treatment processes are usually required on the metal surface. For example, the metal surface is first cleaned to remove impurities and grease. Then, multiple processes, such as sandblasting, priming, polishing, puttying, drying, and sanding, are sequentially performed on the cleaned metal surface. The graphic film can only be attached after confirming that the metal surface is flat. The above-mentioned existing methods are time-consuming and complicated.

[0003] Therefore, it is important to develop a convenient, simple, and quick method for applying graphic films onto metal surfaces, particularly vehicle body surfaces. Summary of the Invention

[0004] Starting from the above technical problems, the object of the present invention is to provide a two-part curing composition for metal surface treatment, a method for attaching a film to the surface of a vehicle body, and a surface structure. When applied, the two-part curing composition has good open time and surface drying time, and has very high bonding strength and aging resistance to the treated metal surface. In addition, the use of the two-part curing composition can realize convenient, simple, and quick attachment of the film to the metal surface.

[0005] The inventors have carried out intensive and detailed research to achieve the present invention.

[0006] According to one aspect of the present invention, there is provided a two-part curing composition for metal surface treatment, comprising, based on 100% by weight of the two-part curing composition: 15 to 35 weight percent of a liquid epoxy resin having a viscosity in the range of 200 to 35,000 centipoise at 25°C; 20 to 35% by weight of a curing agent for epoxy resin; 5 to 15 wt. % of a diluent; 10 to 25% by weight of a weight reducer; 5 to 20% by weight of a flame retardant; A two-part curing composition is provided, comprising an A-part and a B-part, wherein the A-part comprises a liquid epoxy resin, the B-part comprises a curing agent for the epoxy resin, and a diluent, a reducer, and a flame retardant are present in one or both of the A-part and the B-part.

[0007] According to another aspect of the present invention, there is provided a method for attaching a film onto a metal surface, comprising the steps of: mixing part A of the two-part curing composition for metal surface treatment described above with part B, and applying the resulting mixture to the metal surface to form a coating; drying the coating; and and attaching a film to the dried coating.

[0008] According to yet another aspect of the present invention, there is provided a surface structure comprising: A metal surface, a coating formed by applying the above-described two-part curing composition for metal surface treatment onto a metal surface; and a film attached to the coating.

[0009] Compared with existing technologies in the art, the present invention has the following advantages: the two-part curing composition for metal surface treatment according to the technical solution of the present invention has good open time and surface drying time when applied, and has very high bonding strength and aging resistance to the treated metal surface. In addition, multiple processes such as sandblasting, priming, polishing, puttying, drying, and sanding are sequentially carried out on the cleaned metal surface, and then a graphic film is applied thereto in the prior art, and the use of the two-part curing composition can realize convenient, simple, and quick installation of the film on the metal surface. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows a schematic cross-sectional view of a surface structure obtained by attaching a graphic film onto a metal surface according to the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] It should be understood that those skilled in the art can contemplate various other embodiments in accordance with the teachings herein and can make modifications thereto without departing from the scope or spirit of the present disclosure. Accordingly, the following specific embodiments are not to be taken in a limiting sense.

[0012] All numbers used in the specification and claims expressing specific dimensions, quantities, and physical properties should be understood to be modified in all instances by the term "about," unless otherwise indicated. Accordingly, unless stated to the contrary, all numerical parameters recited in the above specification and claims are approximations, and one of ordinary skill in the art, utilizing the teachings disclosed herein, can explore and modify these approximations to obtain desired properties. The use of numerical ranges expressed by endpoints includes all numbers within that range and any range within that range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.

[0013] In order to simplify the prior art methods for attaching graphic films to metal surfaces (e.g., the surface of a vehicle body), the inventors of the present invention have conducted intensive research. Specifically, the inventors have found that when the composition of the surface treatment composition and its contents is specifically selected, it is possible to provide a surface treatment composition that allows a graphic film to be firmly attached to a metal surface without complicated operations such as priming and puttying on the substrate surface in advance.

[0014] According to one aspect of the present invention, there is provided a two-part curing composition for metal surface treatment, comprising, based on 100% by weight of the two-part curing composition: 15 to 35 weight percent of a liquid epoxy resin having a viscosity in the range of 200 to 35,000 centipoise at 25°C; 20 to 35% by weight of a curing agent for epoxy resin; 5 to 15 wt. % of a diluent; 10 to 25% by weight of a weight reducer; 5 to 20% by weight of a flame retardant; A two-part curing composition is provided, comprising an A-part and a B-part, wherein the A-part comprises a liquid epoxy resin, the B-part comprises a curing agent for the epoxy resin, and a diluent, a reducer, and a flame retardant are present in one or both of the A-part and the B-part.

[0015] According to the technical solution of the present invention, a two-part curing composition containing a liquid epoxy resin and a curing agent for the epoxy resin is used as a surface treatment agent for metal surfaces, and then a graphic film is conveniently and firmly attached to the surface. The two-part curing composition forms a cured coating on the metal surface through a curing reaction between the liquid epoxy resin contained in Part A and the curing agent for the epoxy resin contained in Part B, and the cured coating has good adhesion to the metal surface and firmly adheres to the subsequently attached graphic film.

[0016] According to a specific preferred embodiment of the present invention, the two-part curing composition contains 15 to 35 wt%, preferably 25 to 30 wt%, of a liquid epoxy resin, based on 100 wt% of the two-part curing composition, to improve the reactivity between the epoxy resin and the epoxy resin accelerator and the operability of the resulting two-part curing composition. Additionally, to improve the performance of sufficient mixing and reaction between the epoxy resin and the epoxy resin accelerator, the viscosity of the liquid epoxy resin at 25°C is in the range of 200 to 35,000 centipoise, preferably 5,000 to 15,000 centipoise.

[0017] The term "epoxy resin" according to the present invention has the general meaning generally recognized in the art, and refers to an organic epoxy compound containing two or more epoxy groups in the molecule. Any organic compound having an oxirane ring polymerizable by a ring-opening reaction can be used as the epoxy resin in the technical solution according to the present invention, as long as the epoxy resin is in a liquid state at room temperature and has a viscosity in the range of 200 to 35,000 centipoise at 25°C. Preferably, the liquid epoxy resin is an aliphatic epoxy resin, cycloaliphatic epoxy resin, aromatic epoxy resin, heterocyclic epoxy resin, or a combination thereof. In the present invention, organic epoxy compounds containing two to four epoxy groups in the molecule are preferably used. To meet the above requirements regarding liquid form and viscosity range, the epoxy equivalent weight of the liquid epoxy resin is preferably in the range of 100 to 500, preferably 150 to 300. Specifically, the liquid epoxy resin is one or more selected from the group consisting of alkylene oxides, alkenyl oxides, glycidyl esters, glycidyl ethers, epoxy novolacs, glycidyl acrylates, and polyurethane polyepoxides. More preferred epoxy resins include epoxy resins containing glycidyl ethers or polyglycidyl ethers of mono-, di-, or polyhydric phenols, or epoxy resins composed of glycidyl ethers or polyglycidyl ethers of mono-, di-, or polyhydric phenols. Examples of mono-, di-, or polyhydric phenols include, but are not limited to, bisphenol A, bisphenol F, and polymers containing repeating units containing these phenols. Most preferably, the liquid epoxy resin is bisphenol A diglycidyl ether or bisphenol F diglycidyl ether.Examples of commercially available epoxy resins useful in the present invention include bisphenol A diglycidyl ethers, such as EPON 828 (liquid; epoxy equivalent weight: 185-192; viscosity at 25° C.: 11,000-15,000 centipoise), EPON 830 (liquid; epoxy equivalent weight: 190-198; viscosity at 25° C.: 17,000-22,500 centipoise), and EPON 1001F (liquid; epoxy equivalent weight: 525-550; viscosity at 25° C.: 7,000-9,600 centipoise), available from Hexion Specialty Chemicals GmbH, Rosbach, Germany, and Dow Chemical Co.; DER-331 (liquid; epoxy equivalent weight: 182-192; viscosity at 25°C: 11,000-14,000 centipoise) and DER-332 (liquid; epoxy equivalent weight: 171-175; viscosity at 25°C: 4,000-6,000 centipoise) available from Dainippon Ink and Chemicals, Inc.; bisphenol F diglycidyl ethers such as EPICLON 830 (liquid; epoxy equivalent weight: 165-180; viscosity at 25°C: 3,000-4,000 centipoise) available from Dainippon Ink and Chemicals, Inc., and DER-354 (liquid; epoxy equivalent weight: 167-174; viscosity at 25°C: 3,400-4,200 centipoise) available from Dow Chemical Co.; and other bisphenol-based epoxy resins such as Hexion Specialty and EPIKOTE 828 (liquid; epoxy equivalent weight: 184-190; viscosity at 25°C: 12,000-14,000 centipoise) available from Epilox GmbH, Rosbach, Germany, and EPILOX A 18-00 (liquid; epoxy equivalent weight: 175-185; viscosity at 25°C: 8,000-10,000 centipoise) available from Leuna Epilox GmbH, Leuna, Germany.

[0018] The two-part curing composition according to the present invention further comprises one or more epoxy curing agents, i.e., compounds that react with the alkylene oxide ring of the epoxy resin (i.e., epoxide) to crosslink. To avoid premature curing of the two-part curing composition, the liquid epoxy resin and the epoxy resin curing agent should be disposed separately. Preferably, the two-part curing composition comprises Part A and Part B, where Part A comprises the liquid epoxy resin and Part B comprises the epoxy resin curing agent. The specific type of epoxy resin curing agent present in Part B to cure the liquid epoxy resin during mixing of Part A and Part B is not particularly limited and can be appropriately selected from curing agents commonly used in the prior art to cure epoxy resins. According to the technical solution of the present invention, a single type of epoxy resin curing agent can be used. However, instead of a single curing agent, a mixed system of epoxy resin curing agents, i.e., a combination of multiple curing agents, or a combination of one or more curing agents and a curing catalyst, can be used. Preferably, the ratio of the epoxy resin curing agent to the epoxy resin is selected so that they have approximately the same equivalent weight, i.e., the molar ratio of reactive amino groups (or reactive anhydride groups) in the epoxy resin curing agent to reactive epoxy groups in the epoxy resin is about 1:1 or 0.9:1 to about 1:0.9. Based on 100% by weight of the two-part curing composition, the two-part curing composition contains 20 to 35% by weight, preferably 20 to 25% by weight, of the epoxy resin curing agent.

[0019] Preferably, the curing agent for the epoxy resin is selected from an amine curing agent, an anhydride curing agent, or a combination thereof. The amine curing agent contains at least one primary amine (—NH2), and preferred amine curing agents contain at least one modified polyamine, such as an aliphatic linear polyamine or a polyamide polyamine. Examples of amine curing agents useful in the present invention include, but are not limited to, ethylenediamine, diethylenediamine, diethylenetriamine, triethylenetetramine, propylenediamine, tetraethylenepentamine, hexaethyleneheptamine, hexamethylenediamine, 2-methyl-1,5-pentylenediamine, and the like. Other amine curing agents having a group selected from heteroalkylene groups, such as heteroalkylene groups having oxygen as a heteroatom, can also be used in the present invention. For example, the amine curing agent may be aminoethylpiperazine; 4,7,10-trioxatridecane-1,13-diamine (TTD), available from TCI America (Portland, OR), USA; or poly(alkyleneoxy)diamines (also known as polyetherdiamines), such as poly(ethyleneoxy)diamine, poly(propyleneoxy)diamine, or copolymers thereof. Commercially available polyetherdiamines are available from Huntsman Corporation (The Woodlands, TX, USA) under the trade name JEFFAMINE. Anhydride curing agents useful in the present invention include, but are not limited to, phthalic anhydrides, with tetrahydroxyphthalic anhydride, hexahydroxyphthalic anhydride, or norbornenephthalic anhydride being preferred. Methylnorbornenephthalic anhydride and methyltetrahydrophthalic anhydride are particularly preferred. Amine curing agents for epoxy resin Ancamide 910, manufactured by Evonik Industries AG, can be used.

[0020] The two-part curing composition for metal surface treatment according to the present invention further comprises at least one diluent. The diluent is used to adjust the flowability of the two-part curing composition during mixing and use, facilitating application to metal surfaces. Based on 100% by weight of the two-part curing composition, the two-part curing composition comprises 5 to 15% by weight, preferably 7 to 10% by weight, of the diluent. Preferably, the diluent is a non-reactive or reactive diluent. Non-reactive diluents are selected from benzyl alcohol, butylene orthophthalate, dioctyl phthalate, diallyl phthalate, etc., or combinations thereof. Reactive diluents are selected from resorcinol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, or combinations thereof. An example of a suitable commercially available reactive epoxy diluent is Hexion's Heloxy series of compounds, such as Heloxy 107 (ie, 1,4-bis[(glycidyloxy)methyl]cyclohexane).

[0021] The two-part curing composition for treating metal surfaces according to the present invention further comprises at least one weight reducing agent. The weight reducing agent is used to adjust the weight of the two-part curing composition in order to reduce the mass of the cured coating applied to the metal surface without substantially affecting the mechanical properties (e.g., bond strength) of the cured composition. The density of the weight reducing agent is 0.5 g / cm. 3 Preferably, the weight-reducing agent is in an amount of 0.1 to 0.5 g / cm 3 The weight reducer is preferably a low-density inorganic filler having a density of 0.01 to 0.05. Preferably, the weight reducer is hollow glass microspheres, hollow ceramic microspheres, hollow zirconia microspheres, or the like. The hollow glass microspheres, hollow ceramic microspheres, or hollow zirconia microspheres have an average particle size in the range of 1 to 300 μm, preferably 10 to 100 μm. Particularly preferred hollow inorganic microspheres are, for example, Scotchlite K37 (density: 0.37 g / cm 3 : average particle size: 45 μm) and Scotchlite S38 (density: 0.38 g / cm 3These are glass microspheres available from 3M China Limited under the trade name (average particle size: 40 μm).

[0022] The two-part curing composition for metal surface treatment according to the present invention further comprises at least one flame retardant to provide flame retardant performance. The flame retardant is preferably substantially halogen-free. Based on 100% by weight of the two-part curing composition, the two-part curing composition comprises 5 to 20% by weight, preferably 10 to 15% by weight, of the flame retardant. Preferably, the flame retardant is a phosphorus flame retardant or expanded graphite. The phosphorus flame retardant is selected from, for example, inorganic phosphites such as elemental red phosphorus, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, and aluminum phosphite, preferably elemental red phosphorus and inorganic phosphites. The flame retardant system may also include an optional boron-containing material, such as barium metaborate, calcium metaborate, zinc metaborate, and mixtures thereof. The expanded graphite has a graphite interlayer structure, i.e., expandable graphite. Examples of expanded graphite useful in the present invention include ES 100 C10, ES 250 B5, and ES 350 F5 available from Germany Kropfmuehl Graphite Co., Ltd. / AMG Mining Group, and expanded graphite ADT 1002 provided by Shijiazhuang Kepeng Flame Retardant Material Co. Additionally, commercially available examples of phosphorus flame retardants useful in the present invention include EXOLIT AP 750 and EXOLIT RP 6500 manufactured by Clariant Chemical Co., Ltd.

[0023] According to the technical solution of the present invention, the two-part curing composition for metal surface treatment preferably contains at least one epoxy resin curing accelerator to promote the crosslinking reaction between the liquid epoxy resin and the epoxy resin curing agent. To avoid premature curing of the two-part curing composition, the epoxy resin curing accelerator is present in Part B. Based on 100% by weight of the two-part curing composition, the two-part curing composition contains 2 to 10% by weight, preferably 3 to 7% by weight, of the epoxy resin curing accelerator. Preferably, the epoxy resin curing accelerator is a tertiary amine accelerator. The tertiary amine accelerator is selected from triethylamine, triethanolamine, benzyldimethylamine, dimethylaminomethylphenol, tri(dimethylaminomethyl)phenol, or a combination thereof. A specific example of a commercially available epoxy resin curing accelerator useful in the present invention is Ancamine K54 manufactured by Evonik Industries AG.

[0024] To improve the antioxidant performance of the cured product formed from the two-part curing composition, the two-part curing composition preferably contains at least one antioxidant. The antioxidant may be optionally present in one or both of Parts A and B. Preferably, the antioxidant is a hindered phenolic antioxidant. Based on 100 wt% of the two-part curing composition, the antioxidant is present in the two-part curing composition in an amount of 0.5 to 5 wt%, preferably 1 to 2 wt%. Commercially available antioxidants useful in the two-part curing composition of the present invention include Irganox 1135, Irganox 1726, and Irganox 1520L, manufactured by BASF Co.

[0025] Optionally, the two-part curing composition further comprises at least one wetting agent to improve wetting when the composition is applied to a substrate. The wetting agent may optionally be present in one or both of Parts A and B. Based on 100% by weight of the two-part curing composition, the wetting agent is present in the two-part curing composition in an amount of 0.5 to 5% by weight, preferably 0.5 to 1% by weight. Specific examples of wetting agents that can be used are selected from titanates, silanes, zirconates, zirconium aluminates, phosphate esters, or combinations thereof. Commercially available examples of wetting agents useful in the present invention include W995 from BYK Co.

[0026] The method for preparing the two-part curing composition for metal surface treatment is not particularly limited, and the composition may be prepared by simple mixing. Specifically, the two-part curing composition obtained by mixing comprises separate parts A and B, where part A contains a liquid epoxy resin and part B contains a curing agent for the epoxy resin, and a diluent, a weight reducer, and a flame retardant are present in one or both of parts A and B. In the presence of an epoxy resin curing accelerator, the epoxy resin curing accelerator should coexist with the epoxy resin curing agent in part B. In the presence of an antioxidant and / or humectant, the antioxidant and / or humectant may be present in one or both of parts A and B.

[0027] According to another aspect of the present invention, there is provided a method for attaching a film onto a metal surface, comprising the steps of: mixing part A of the two-part curing composition for metal surface treatment described above with part B, and applying the resulting mixture to the metal surface to form a coating; drying the coating; and and attaching a film to the dried coating.

[0028] The method for applying the composition to the metal surface is not particularly limited, and methods commonly used in the art, such as roller coating, brush coating, and spraying, can be used. To ensure sufficient cohesion of the composition on the metal surface and the firmness of the subsequently attached film, the thickness of the applied coating ranges from 0.2 to 1.0 mm, preferably 0.3 to 0.5 mm. In addition, the method may further include cleaning the metal surface before applying the two-part curing composition to the metal surface. This step may involve wiping the metal surface with a clean cloth. If grease or wax is present on the surface, it is better to wipe it with a solvent such as ethanol, isopropanol, or ethyl acetate, and obtain a clean, dry surface after the solvent evaporates. The cleaning step is very important for achieving good bonding properties. Optionally, the method may further include sanding the surface of the dried coating after drying the coating and before attaching the film. The sanding step can smooth the surface of the dried coating so that the graphic film can be attached evenly and firmly. The sanded surface is then washed with a solvent such as ethanol or isopropanol, and after the solvent has completely evaporated, the film is attached onto the surface.

[0029] The specific structure of the patterned film attached to the metal surface is not particularly limited. Preferably, the film comprises a film layer and an adhesive layer bonded together. The film layer has a pattern intended for marking, warning, or advertising, and the adhesive layer is used to adhere the film layer to the treated metal surface. The specific material constituting the film layer is not particularly limited and can be selected from conventional materials commonly used in the art for forming graphic films. Preferably, the film layer comprises one or more of polyvinyl chloride, polyurethane, and polyethylene terephthalate. Optionally, the film layer has a pattern intended for marking, warning, or advertising on the side away from the adhesive layer. Preferably, the thickness of the film layer is in the range of 50 to 500 μm. In addition, the specific material constituting the adhesive layer is not particularly limited. Preferably, the adhesive layer is a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer preferably comprises an acrylic-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or a silicone-based pressure-sensitive adhesive. Preferably, the thickness of the adhesive layer is in the range of 30 to 200 μm.

[0030] According to another aspect of the present invention, there is provided a surface structure comprising a metal surface, a coating formed by applying the above-described two-part curing composition for metal surface treatment onto the metal surface, and a film attached to the coating. Specifically, Figure 1 shows a schematic cross-sectional view of a surface structure 1 obtained by attaching a graphic film 4 onto a metal surface 2 according to the method of the present invention. Surface structure 1 comprises, in order, the metal surface 2, a coating 3 formed from the above-described two-part curing composition for metal surface treatment applied onto the metal surface 2, and a film 4 (i.e., graphic film) attached to the coating 3.

[0031] In the currently commonly used process for attaching graphic films to metal surfaces, the metal surface must be flat and free of obvious defects such as holes, bumps, and depressions. Therefore, to achieve a firm attachment of a graphic film to a metal surface, the metal surface typically requires multiple surface treatment steps. For example, the metal surface must first be cleaned to remove impurities and grease. Then, multiple treatments, such as sandblasting, priming, polishing, puttying, drying, and sanding, are performed on the cleaned metal surface in sequence. The graphic film can only be attached after ensuring that the metal surface is flat. The above-mentioned attachment methods are time-consuming and complex. According to the technical solution of the present invention, a film can be attached to a clean metal surface after only one coating operation, and the resulting graphic film has very high bonding strength to the metal surface. Therefore, the technical solution of the present invention can realize a convenient, simple, and fast attachment of a film to a metal surface.

[0032] Various exemplary embodiments of the present invention are further illustrated by the following listing of embodiments, which should not be construed as unduly limiting the invention.

[0033] Specific embodiment 1 is a two-part curing composition for treating metal surfaces, comprising, based on 100 wt. % of the two-part curing composition: 15 to 35 weight percent of a liquid epoxy resin having a viscosity in the range of 200 to 35,000 centipoise at 25°C; 20 to 35% by weight of a curing agent for epoxy resin; 5 to 15 wt. % of a diluent; 10 to 25% by weight of a weight reducer; 5 to 20% by weight of a flame retardant; The two-part curing composition for metal surface treatment comprises an A-part and a B-part, wherein the A-part comprises a liquid epoxy resin, the B-part comprises a curing agent for the epoxy resin, and a diluent, a weight reducer, and a flame retardant are present in one or both of the A-part and the B-part.

[0034] Specific embodiment 2 is the two-part curing composition for metal surface treatment according to specific embodiment 1, wherein the liquid epoxy resin has a viscosity in the range of 5,000 to 15,000 centipoise at 25°C.

[0035] Specific embodiment 3 is the two-part curing composition for treating metal surfaces according to specific embodiment 1, wherein the liquid epoxy resin has an epoxy equivalent weight in the range of 100 to 500.

[0036] Certain embodiment 4 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the liquid epoxy resin is one or more selected from the group consisting of alkylene oxides, alkenyl oxides, glycidyl esters, glycidyl ethers, epoxy novolacs, glycidyl acrylates, and polyurethane polyepoxides, and preferably the liquid epoxy resin is bisphenol A diglycidyl ether or bisphenol F diglycidyl ether.

[0037] Certain embodiment 5 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the curing agent for the epoxy resin is selected from an amine curing agent, an anhydride curing agent, or a combination thereof.

[0038] Certain embodiment 6 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the diluent is a non-reactive or reactive diluent, preferably the non-reactive diluent is selected from benzyl alcohol, butylene orthophthalate, dioctyl phthalate, diallyl phthalate, or a combination thereof, and the reactive diluent is selected from resorcinol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, or a combination thereof.

[0039] In particular embodiment 7, the weight loss agent is 0.1 to 0.5 g / cm 3Specific embodiment 1 is a two-part curing composition for treating metal surfaces, wherein the low-density inorganic filler has a density in the range of

[0040] Certain Embodiment 8 is the two-part curing composition for metal surface treatment according to Certain Embodiment 1, wherein the weight reducer is hollow glass microspheres, hollow ceramic microspheres, or hollow zirconia microspheres, and preferably the hollow glass microspheres, hollow ceramic microspheres, or hollow zirconia microspheres have an average particle size in the range of 1 to 300 μm.

[0041] Certain embodiment 9 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the flame retardant is a phosphorus flame retardant or expanded graphite.

[0042] Certain embodiment 10 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the two-part curing composition further comprises an epoxy resin curing accelerator in the B part.

[0043] Certain embodiment 11 is the two-part curing composition for treating metal surfaces according to certain embodiment 10, wherein the two-part curing composition comprises 2 to 10 wt. % of an epoxy resin curing accelerator, based on 100 wt. % of the two-part curing composition.

[0044] Certain embodiment 12 is the two-part curing composition for treating metal surfaces according to certain embodiment 11, wherein the epoxy resin curing accelerator is a tertiary amine accelerator, preferably the tertiary amine accelerator is selected from triethylamine, triethanolamine, benzyldimethylamine, dimethylaminomethylphenol, tri(dimethylaminomethyl)phenol, or a combination thereof.

[0045] Certain embodiment 13 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the two-part curing composition further comprises 0.5 to 5 wt % of a hindered phenolic antioxidant.

[0046] Certain embodiment 14 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the two-part curing composition further comprises 0.5 to 5 wt. % of a wetting agent, the wetting agent being selected from titanates, silanes, zirconates, zirconium aluminates, phosphate esters, or combinations thereof.

[0047] Certain embodiment 15 is the two-part curing composition for treating metal surfaces according to certain embodiment 1, wherein the metal surface is the surface of a vehicle body.

[0048] Certain embodiment 16 is a method for attaching a film onto a metal surface, comprising: Mixing part A of the two-part curing composition for treating metal surfaces according to any one of specific embodiments 1 to 15 with part B, and applying the resulting mixture to the metal surface to form a coating; drying the coating; and and attaching a film to the dried coating.

[0049] Certain embodiment 17 is the method for attaching a film onto a metal surface according to certain embodiment 16, wherein the coating thickness ranges from 0.2 to 1.0 mm.

[0050] Certain embodiment 18 is the method for attaching a film onto a metal surface according to certain embodiment 16, wherein the method further comprises cleaning the metal surface before applying the two-part curing composition to the metal surface.

[0051] Certain embodiment 19 is the method for attaching a film onto a metal surface of certain embodiment 16, wherein the method further comprises sanding the surface of the dried coating after drying the coating and before attaching the film.

[0052] Certain embodiment 20 is the two-part curing composition for treating metal surfaces according to certain embodiment 16, wherein the film comprises a film layer and an adhesive layer adhered to one another.

[0053] Certain embodiment 21 is a method for attaching a film onto a surface of a vehicle body according to certain embodiment 20, wherein the film layer comprises one or more of polyvinyl chloride, polyurethane, and polyethylene terephthalate.

[0054] Certain embodiment 22 is the method for attaching a film onto a metal surface according to certain embodiment 20, wherein the thickness of the film layer ranges from 50 to 500 μm.

[0055] Certain embodiment 23 is the method for attaching a film onto a metal surface according to certain embodiment 20, wherein the adhesive layer is a pressure-sensitive adhesive layer.

[0056] Certain embodiment 24 is the method for attaching a film onto a metal surface according to certain embodiment 20, wherein the thickness of the adhesive layer ranges from 30 to 200 μm.

[0057] Particular embodiment 25 is a surface structure comprising: A metal surface, A coating formed by applying the two-part curing composition for treating metal surfaces according to any one of specific embodiments 1 to 15 onto a metal surface; and a film attached to the coating.

[0058] The present invention will be described in more detail below in combination with embodiments. It should be noted that these descriptions and embodiments are not intended to limit the present invention, but to facilitate understanding of the present invention. The protection scope of the present invention shall be as defined in the accompanying claims.

[0059] Embodiment In the present invention, unless otherwise specified, all the reagents used are commercially available products and are used directly without further purification. [Table 1]

[0060] Test Method Viscosity of the mixture Separately, parts A and B of the two-part curing compositions prepared in the following examples and comparative examples were mixed to homogeneity to obtain the mixtures to be applied. The viscosities (MPa·s) of the mixtures were then measured using a Brookfield Co. viscosity tester (Model HB DV2T) using a No. 64 rotor set at a rotation speed of 2 revolutions per minute.

[0061] Mixture open time Separately, parts A and B of the two-part curing compositions prepared in the following examples and comparative examples were mixed to homogeneity to obtain a mixture to be applied. 200 g of the mixture was allowed to stand for half an hour, and samples were taken every 5 minutes to observe whether the mixture could be uniformly coated onto a stainless steel plate (dimensions: 12 cm x 5 cm) until the viscosity of the mixture increased significantly to the point where it could no longer be smoothly coated onto the steel plate. The open time (unit: minutes) was recorded from the time the sample was mixed to the time it could no longer be applied.

[0062] Surface drying time of the mixture The A and B parts of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 200 g of the mixture was poured onto a glass plate approximately 100 mm long, and then the poured mixture was smeared with a scraper to a thickness of 1 to 2 mm to obtain a glass plate specimen to which the mixture was applied. The glass plate specimen was left to stand at 23±2°C for 50 minutes, and then a smooth glass rod was used to gently touch the mixture coating on the glass plate specimen at three different locations. This operation was repeated every 5 minutes until the mixture was lifted from the mixture coating but did not stain the glass rod. The time from when the mixture was applied to when the mixture could be lifted by the glass rod without adhering to the glass plate was recorded as the surface drying time (unit: minutes).

[0063] density Separately, parts A and B of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 15 g of the mixture was cast into a mold having a cavity with dimensions of 1.25 cm x 1.25 cm x 10 cm. Then, the mold was cured in a fan oven at 80°C for 2 hours to prepare a test specimen. The cured test specimen was removed from the mold, and its exact volume was recorded (unit: cm). 3 ) The weight (g) of each specimen was measured, and its density was calculated as g / cm 3 It was recorded at.

[0064] Bond strength of the hardened product of the mixture to a stainless steel plate The A and B parts of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 5 g of the mixture was poured onto a clean stainless steel plate (dimensions: 12 cm x 5 cm), spread with a scraper to form a thin layer of approximately 1 mm, and left at room temperature for 24 hours. The surface was polished with 80-grit sandpaper and cleaned. A 1-inch-wide anodized aluminum plate was then bonded to the polished surface with a bonding area of ​​1 square inch using a structural adhesive. The resulting sample was then stretched using an Instron tensile machine (Model 5965) at a tension rate of 5 mm / min until the sample's structure was damaged. The bond strength of the cured product of the mixture to the stainless steel plate was recorded in MPa. At least three samples were measured each time, and the average value was obtained.

[0065] Surface condition of the aged and cured product of the mixture (weather resistance) The A and B parts of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 5 g of the mixture was poured onto a clean stainless steel plate (dimensions: 12 cm x 5 cm), spread with a scraper to form a thin layer approximately 1-2 mm thick, and left at room temperature for 24 hours. The resulting sample was then subjected to the following aging treatment, which included the following sequential steps: 4 hours at 80°C, 0.5 hours at room temperature, 4 hours at -40°C, 0.5 hours at room temperature, and 4 hours at 70°C and 95% relative humidity. The aging treatment was repeated 10 times. The aged sample was removed, left at room temperature for 24 hours, and then observed for the presence of bubbles, embrittlement, and cracks on the surface. Samples without bubbles, embrittlement, or cracks were designated "pass."

[0066] Bond strength of film attached to substrate The A and B parts of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 5 g of the mixture was poured onto a clean stainless steel plate (dimensions: 12 cm x 5 cm), spread with a scraper to form a thin layer of approximately 1 mm, and left at room temperature for 24 hours. The surface was polished with 80-grit sandpaper and cleaned. According to the ASTM D3330 test method, 3M180MC adhesive film manufactured by 3M China Limited was cut to a width of 25 mm. After removing the release paper, it was adhered to the cleaned surface of the cured product and rolled back and forth once on a 2.5 kg rubber roller. After leaving the sample obtained in the above process for 20 minutes, the peel force of the adhesive film on the surface of the cured product was measured using an Instron tensile tester (Model 5965) at a pulling speed of 300 mm / min, and the results were recorded in N / mm. At least three samples were measured each time, and the average value was obtained.

[0067] Surface condition of aged film (weather resistance) / peel strength Separately, parts A and B of the two-part curing compositions prepared in the following examples and comparative examples were mixed homogeneously to obtain the mixture to be applied. 5 g of the mixture was poured onto a clean stainless steel plate (dimensions: 12 cm x 5 cm), spread with a scraper to form a thin layer of approximately 1 mm, and left at room temperature for 24 hours. The surface was polished with 80-grit sandpaper and cleaned. According to the ASTM D3330 test method, 3M180MC adhesive film (manufactured by 3M China Limited) was cut to a width of 40 mm. After removing the release paper, it was adhered to the cleaned surface of the cured product, and a 2.5 kg rubber roller was rolled back and forth once on it.

[0068] The samples obtained through the above process were placed in a cooling and heating cycle aging box for weather resistance testing. The aging box was set as follows: 80°C, 95% RH for 4 hours, then the temperature was ramped to -40°C at a rate of 1°C / min and held at that condition for 4 hours, and then the temperature was ramped to 80°C, 95% RH at a rate of 1°C / min and held at that condition for 4 hours. This 12-hour cycle was repeated for a total of 10 times. The samples were then removed and visually inspected for the presence of bubbles on the surface. After leaving the samples for 24 hours, the adhesive film on the surface of the cured product was measured at a tensile speed of 300 mm / min using an Instron tensile tester (Model 5965) according to ASTM D3330 test method, and the results were recorded in N / mm. At least three samples were measured each time, and the average value was obtained.

[0069] Embodiment 1 In Example 1, a two-part curing composition 1 was prepared, which included independent parts A and B. Preparation of part A involved homogeneously mixing 28 g of bisphenol A diglycidyl ether (DER-331), 9 g of 1,4-bis[(glycidyloxy)methyl]cyclohexane (Heloxy 107), 0.5 g of phosphate polyester copolymer (W995), 13 g of glass microspheres (Scotchlite S38), 10 g of expanded graphite (ADT 1002), and 5 g of phosphorus flame retardant (EXOLIT RP 6500) according to the ratios in Table 2 below. Preparation of Part B involved homogeneously mixing 1.5 g of isooctyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate (Irganox 1135), 30 g of polyamide curing agent (Ancamide 910), and 3 g of 2,4,6-tris(dimethylaminomethyl)phenol (Ancamine K54) according to the ratios in Table 2 below.

[0070] The two-component thermally conductive adhesive composition 1 obtained according to the above steps was tested according to the above-described embodiments for the viscosity of the mixture, the open time of the mixture, the surface drying time of the mixture, the density of the cured product of the mixture, the bond strength of the cured product of the mixture to a stainless steel plate, the surface condition of the aged cured product of the mixture, the bond strength of the film attached to a substrate, and the surface condition / peel strength of the aged film. The test results obtained are shown in Table 3.

[0071] Examples 2 to 4 and Comparative Examples 1 to 3 Two-part curing compositions 2 to 4 and comparative two-part curing compositions 1 to 3 were each prepared in the same manner as in Example 1 according to the ratios in Table 2 shown below.

[0072] Two-part curing compositions 2 to 4 obtained according to the above steps and comparative two-part curing compositions 1 to 3 were tested in accordance with the above detailed description of the invention regarding the method for measuring the viscosity of the mixture, the open time of the mixture, the surface drying time of the mixture, the density of the cured product of the mixture, the bond strength of the cured product of the mixture to a stainless steel plate, the surface condition of the aged cured product of the mixture, the bond strength of the film attached to a substrate, and the surface condition / peel strength of the aged film. The test results obtained are shown in Table 3.

[0073] Comparative Example 4 In Comparative Example 4, the film was attached to a stainless steel plate by conventional methods in the art.

[0074] Specifically, 3MPN1089 body filler (manufactured by 3M China Limited) was applied to a stainless steel plate (dimensions: 12 cm x 5 cm) at a thickness of approximately 1 mm, dried at 80°C for 2 hours, and then left at room temperature for 24 hours. The coating was sanded with 80-grit sandpaper and the surface was cleaned. 3M180MC adhesive film (manufactured by 3M China Limited) was cut to a width of 25 mm and, after removing the release paper, adhered to the cleaned surface of the cured product. A 2.5 kg rubber roller was rolled back and forth once on top of it.

[0075] The samples obtained through the above process were placed in a cooling and heating cycle aging box for weather resistance testing. The aging box was set as follows: 80°C, 95% RH for 4 hours, then the temperature was ramped to -40°C at a rate of 1°C / min and held at that condition for 4 hours, and then the temperature was ramped to 80°C, 95% RH at a rate of 1°C / min and held at that condition for 4 hours. This 12-hour cycle was repeated for a total of 10 times. The samples were then removed and visually inspected for the presence of bubbles on the surface. After leaving the samples for 24 hours, the adhesive film on the surface of the cured product was measured at a tensile speed of 300 mm / min using an Instron tensile tester (Model 5965) according to ASTM D3330 test method, and the results were recorded in N / mm. At least three samples were measured each time, and the average value was obtained. [Table 2] [Table 3]

[0076] The results shown in Tables 2 and 3 above demonstrate that, when the composition of the surface treatment composition and its components is specifically selected within the scope of the present invention, a surface treatment composition can be provided that allows a graphic film to be firmly attached to a metal surface without complicated operations such as prior priming and puttying of the substrate surface. When applied, the two-part curing composition has good open time and surface drying time, and exhibits very high bond strength and aging resistance to the surface of the treated stainless steel plate. The use of the two-part curing composition allows for convenient, simple, and quick attachment of a film to the surface of a stainless steel plate.

[0077] By comparing the results of Comparative Example 1 with those of Examples 1 to 4, it can be seen that when the content of diluent in the two-part curing composition is low (less than 5 wt%), the bond strength of the cured product of the mixture to the stainless steel plate is reduced, the aging performance of the cured product of the mixture is deteriorated, and the bond strength of the film adhered to the substrate by the composition is reduced and its aging performance is deteriorated.

[0078] Comparing the results of Comparative Example 2 with those of Embodiments 1 to 4, when the content of the curing accelerator in the two-part curing composition is too high (more than 10 wt%), the mixture obtained by mixing Part A with Part B has a shorter open time, which is not conducive to the film installation operation.

[0079] By comparing the results of Comparative Example 3 with those of Examples 1 to 4, it can be seen that when the content of liquid epoxy resin in the two-part curing composition is too low (less than 15 wt%), the mixture obtained by mixing Part A with Part B will have too high a viscosity, resulting in a decrease in the bonding strength of the cured product of the mixture to the stainless steel plate, a deterioration in the aging performance of the cured product of the mixture, and a decrease in the bonding strength of the film adhered to the substrate by the composition, as well as a deterioration in its aging performance.

[0080] By comparing the results of Comparative Example 4 with those of Embodiments 1 to 4, it can be seen that the two-part curing composition for metal surface treatment prepared according to the method of the present invention provides bond strength of a film attached to a substrate, aging performance of the film, etc. that are comparable to or even better than those of films obtained according to the complicated processes of the prior art.

[0081] While the particular embodiments described above include many specific details for illustrative purposes, those skilled in the art will appreciate that many variations, modifications, substitutions, and alterations to these details are all within the scope of the invention as claimed. Accordingly, the disclosure described in the particular embodiments does not pose any limitations on the invention as claimed in the claims. The appropriate scope of the invention is to be defined by the claims and their appropriate legal equivalents. All references are incorporated herein by reference in their entirety.

Claims

1. A two-part curing composition for treating metal surfaces, comprising, based on 100% by weight of the two-part curing composition: 25 to 35% by weight of a liquid epoxy resin having a viscosity in the range of 200 to 35,000 centipoise at 25°C and being bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; 20 to 35 wt. % of an epoxy resin curing agent which is a polyamide curing agent; 5 to 15 wt. % of a diluent which is cyclohexanedimethanol diglycidyl ether; 10 to 25 wt. % of a weight reducer; 5 to 20 wt. % of a flame retardant; 2 to 10 weight percent of an epoxy resin cure accelerator that is a tertiary amine accelerator; Including, The two-part curing composition for metal surface treatment comprises a part A and a part B, wherein the part A comprises the liquid epoxy resin, the part B comprises a curing agent for the epoxy resin, and the diluent, the reducer, and the flame retardant are present in one or both of the part A and the part B.

2. 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the liquid epoxy resin has a viscosity in the range of 5,000 to 15,000 centipoise at 25°C.

3. 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the liquid epoxy resin has an epoxy equivalent weight in the range of 100 to 500.

4. The weight reducing agent has a density of 0.1 to 0.5 g / cm ３ 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the weight reducer is a low-density inorganic filler having a density in the range of 0.1 to 1.0, or the weight reducer is hollow glass microspheres, hollow ceramic microspheres, or hollow zirconia microspheres.

5. The two-part curing composition for metal surface treatment according to claim 1, wherein the weight reducer is hollow glass microspheres, hollow ceramic microspheres, or hollow zirconia microspheres, the average particle size of which is in the range of 1 to 300 μm.

6. 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the flame retardant is a phosphorus flame retardant or expanded graphite.

7. 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the two-part curing composition further comprises 0.5 to 5% by weight of a hindered phenolic antioxidant.

8. 2. The two-part curing composition for treating metal surfaces according to claim 1, wherein the two-part curing composition further comprises 0.5 to 5% by weight of a wetting agent.

9. The two-part curing composition for metal surface treatment according to claim 8, wherein the wetting agent is selected from titanates, silanes, zirconates, zirconium aluminates, phosphate esters, or combinations thereof.

10. 2. The two-part curing composition for metal surface treatment according to claim 1, wherein the metal surface is the surface of a vehicle body.

11. 1. A method for attaching a film onto a metal surface, comprising: mixing the part A of the two-part curing composition for metal surface treatment according to any one of claims 1 to 10 with the part B, and applying the resulting mixture to the metal surface to form a coating; drying the coating; attaching the film to the dried coating; A method comprising:

12. 12. The method for attaching a film onto a metal surface according to claim 11, wherein the thickness of the coating ranges from 0.2 to 1.0 mm.

13. 12. The method for attaching a film onto a metal surface of claim 11, wherein the film comprises a film layer and an adhesive layer adhered to one another.

14. 14. The method for attaching a film onto a metal surface of claim 13, wherein the film layer comprises one or more of polyvinyl chloride, polyurethane, and polyethylene terephthalate.

15. A surface structure comprising: A metal surface, A coating formed by applying the two-part curing composition for metal surface treatment according to any one of claims 1 to 10 onto the metal surface; a film attached onto the coating.

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