Protective varnish for decoration as well as preparation method and application thereof

Abstract

The invention provides protective varnish for decoration as well as a preparation method and application thereof, and relates to the technical field of noble metal coatings. The protective varnish for decoration comprises a molding main agent, a polyurethane curing agent and a first diluent. The main film forming agent comprises the following components in percentage by mass: 50-85% of hydroxy acrylic resin and 10-30% of castor oil modified short oil alkyd resin. According to the protective varnish for decoration, the castor oil modified short-oil alkyd resin is selected, the alkyd resin is endowed with higher flexibility and impact resistance by the long-chain fatty acid structure of castor oil, and the cracking risk of a coating is reduced; compared with the prior art, the alkyd resin with short oil length can directly react with a curing agent isocyanate to generate a flexible polyurethane chain segment, the crosslinking density is reduced, the elasticity of a paint film is improved, the flexibility of the paint film can be improved, in addition, the alkyd resin with short oil length can improve the curing speed compared with the alkyd resin with long oil length, and thus the curing rate of the protective paint is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of precious metal coatings, and in particular to a decorative protective varnish and a preparation method and application thereof. Background Art

[0002] With the increase in cultural and creative products such as plaques, murals, and Buddha statues, gold or silver foil is usually affixed to the surface of the substrate in order to reduce the use of gold and silver. However, the operation process is relatively complicated and not conducive to mass production.

[0003] Furthermore, products containing precious metals used in outdoor environments require a protective coating. This not only creates a beautiful and elegant appearance, but also protects the product's surface, improving its weather resistance and preventing oxidation and corrosion of the precious metals. This requires a protective coating with excellent weather resistance, good fullness, fast drying speed, and strong adhesion.

[0004] The commonly used protective paint resins in the industry are hydroxy acrylic resin and alkyd resin; hydroxy acrylic resin has good weather resistance and gloss retention, strong adhesion to the material surface, but poor fullness and flexibility. Compared with hydroxy acrylic resin, alkyd resin has better fullness, but the coating film is softer, has poor water and alkali resistance, and is not flexible enough.

[0005] To increase the toughness of the paint film, different resin types need to be combined, considering not only the compatibility between the resins but also the varying reaction rates between the resin and the curing agent. Differences in curing speed can lead to asynchronous shrinkage in different regions of the resin, resulting in internal stress concentrations that can cause cracks or warping. Therefore, it is necessary to increase the curing agent content or increase the type of curing agent to balance the curing rates, or to rely more heavily on catalysts to improve curing efficiency, resulting in a more complex formulation.

[0006] Therefore, it is necessary to develop a protective paint with relatively simple ingredients, excellent performance, and suitable for spraying on precious metal paint surfaces. Summary of the Invention

[0007] In response to the shortcomings of the above-mentioned prior art, the present invention aims to provide a decorative protective varnish, its preparation method, and its application. This decorative protective varnish utilizes a hydroxylated acrylic resin in combination with a castor oil-modified short-oil alkyd resin. The long-chain fatty acid structure of castor oil imparts greater flexibility and impact resistance to the alkyd resin, reducing the risk of coating cracking. Furthermore, the castor oil-modified short-oil alkyd resin contains a large number of hydroxyl (-OH) groups, which can directly react with the curing agent isocyanate to form flexible polyurethane segments, reducing crosslink density and increasing film elasticity, thereby improving film flexibility. Furthermore, the short-oil alkyd resin cures faster than long-oil alkyd resins, thereby increasing the curing rate of the protective varnish.

[0008] To achieve the above-mentioned object, the present invention provides a decorative protective varnish, comprising a molding base, a polyurethane curing agent, and a first diluent; the molding base comprises the following components, calculated by mass: 50-85% of a hydroxylated acrylic resin, 10-30% of a castor oil-modified short oil alkyd resin, 1-10% of n-butyl acetate, 1-10% of propylene glycol monomethyl ether acetate, 0.1-0.5% of a dehydrating agent, 0.1-0.5% of a defoaming agent, 0.3-3% of a leveling agent, 0.1-0.5% of an anti-sagging agent, 0.1-1% of an ultraviolet absorber, 0.1-1% of an ultraviolet stabilizer, 0.01-0.3% of a catalyst, and 0.3-0.8% of a dispersant;

[0009] The polyurethane curing agent comprises the following components: 50-80% aliphatic isocyanate, 5-25% n-butyl acetate, and 5-20% propylene glycol monomethyl ether acetate;

[0010] The first diluent comprises the following components: 40-60% of n-butyl acetate, 20-40% of propylene glycol monomethyl ether acetate, and 5-25% of isoamyl acetate.

[0011] Furthermore, the mass ratio of the molding main agent, the polyurethane curing agent, and the first diluent is (1-5):1:(0.1-1).

[0012] Furthermore, the castor oil-modified short oil alkyd resin has a solid content of 60-80%, a hydroxyl value of 100-150 mg KOH / g, and a viscosity (25°C) of 15,000-25,000 mPa·s. Preferably, the castor oil-modified short oil alkyd resin is of at least one type selected from FX-6701 and FX-6703.

[0013] Furthermore, the hydroxy acrylic resin has a solid content of 70-85%, a hydroxyl content of 2%-6%, and a viscosity (25°C) of 2000-10000 mPa·s. Preferably, the hydroxy acrylic resin is at least one of Setalux 1903BA-75 and Setalux 1753SS-70.

[0014] The dehydrating agent is at least one of toluenesulfonic acid isocyanate and vinyltrimethoxysilane.

[0015] The defoaming agent is at least one of AX3301 and BYK-051.

[0016] The leveling agent is at least one of BYK-306 and BYK-310.

[0017] The anti-sagging agent is at least one of Sothix 250 and BYK430.

[0018] The ultraviolet light absorber is at least one of Tinuvin 328 and Tinuvin 900.

[0019] The ultraviolet light stabilizer is at least one of Tinuvin 292 and Tinuvin 249.

[0020] The catalyst is at least one of dibutyltin dilaurate, triethylenediamine and zinc isooctanoate.

[0021] Furthermore, the dispersant is one or both of KH560 and KH570.

[0022] Furthermore, the aliphatic isocyanate is hexamethylene diisocyanate trimer. Preferably, the specific model of the hexamethylene diisocyanate trimer is at least one of HT-100 and Coronate HXR.

[0023] To achieve the above-mentioned objectives, the present invention also provides a method for preparing the aforementioned decorative protective varnish, comprising the following steps: separately preparing a molding base, a polyurethane curing agent, and a first diluent, then uniformly mixing them in a mass ratio of molding base: polyurethane curing agent = (1-5):1, and finally adding the first diluent to adjust the viscosity to reach the construction viscosity, stirring evenly, and thus obtaining the decorative protective varnish.

[0024] The decorative protective varnish can be used as a protective layer of precious metal paint products, comprising the following steps:

[0025] S1, heating and stirring an organic resin and an organic solvent until fully dissolved to obtain an organic vehicle, adding the organic vehicle and a dispersant to the precious metal powder, stirring evenly, and finally adding a diluent and stirring evenly to obtain a precious metal paint;

[0026] S2, spraying the precious metal paint on the surface of the substrate, drying naturally or by heating, after the first coat of metallic paint is completely dried, spraying the metallic paint again and drying, and finally spraying the decorative protective varnish on the surface of the metallic paint, which forms a protective layer after drying.

[0027] Furthermore, the precious metal paint comprises the following components: by mass fraction, 10-50% precious metal powder, 1-10% organic resin, 3-25% organic solvent, 0.3-1% dispersant, and 35-65% diluent.

[0028] Furthermore, the noble metal powder has a flake shape, a flake diameter of 5 to 30 μm, and a thickness of 50 to 300 nm; the noble metal is one of gold and silver.

[0029] Furthermore, the organic resin is composed of one or more of cellulose acetate butyrate, ethyl cellulose, acrylic resin, and polyvinyl butyral.

[0030] The organic solvent is composed of one of dimethyl adipate, alcohol ester dodecyl ester, terpineol, and one or more of diethylene glycol butyl ether acetate.

[0031] The diluent is at least one of camphor oil and isoamyl acetate.

[0032] The dispersant is at least one of KH550, KH560, and KH570.

[0033] The beneficial effects of the present invention are:

[0034] 1. The decorative protective varnish provided by the present invention uses a hydroxyl acrylic resin in combination with a castor oil-modified short-oil alkyd resin. The long-chain fatty acid structure of castor oil gives the alkyd resin higher flexibility and impact resistance, reducing the risk of coating cracking. On the other hand, the castor oil-modified short-oil alkyd resin contains a large amount of hydroxyl groups (-OH), which can directly react with the curing agent isocyanate to generate flexible polyurethane segments, reduce the cross-linking density and increase the elasticity of the paint film, thereby improving the flexibility of the paint film. In addition, the selection of short-oil alkyd resin will increase the curing speed compared to long-oil alkyd resin, thereby increasing the curing rate of the protective paint.

[0035] 2. The decorative protective varnish provided by the present invention uses a silane dispersant, in which the epoxy group or methoxy group can react with the hydroxyl group (-OH) of the hydroxy acrylic resin to form a stable chemical bond, thereby enhancing the interfacial bonding strength. At the same time, the silanol group (Si-OH) generated by the hydrolysis of the dispersant can combine with the ester group or residual hydroxyl group of the alkyd resin, further promoting the coupling of the two phases, thereby increasing the compatibility of the two resins.

[0036] 3. The precious metal paint prepared using flaky precious metal powder in the present invention has a purer metallic color and better brightness after being sprayed onto the surface of the substrate compared to the paint prepared using spherical precious metal powder at the same metal content and the same viscosity.

[0037] 4. The decorative protective varnish of the present invention is used as a protective layer for precious metal paint. The components of the two paints are appropriately matched, both have good film-forming properties, good adhesion, and beautiful appearance. The precious metal paint uses a thermoplastic resin, while a curing agent is added to the protective paint. Therefore, both paints can be dried naturally or at low temperature, and are suitable for outdoor use. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a photo of the object after spraying the gold paint prepared in Example 1.

[0039] Figure 2 For Figure 1 The actual picture after spraying the decorative protective varnish prepared in Example 4 on the basis. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0042] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0043] The present invention provides a decorative protective varnish, comprising a molding base, a polyurethane curing agent, and a first diluent. The molding base comprises the following components, calculated by mass: 50-85% of a hydroxylated acrylic resin, 10-30% of a castor oil-modified short oil alkyd resin, 1-10% of n-butyl acetate, 1-10% of propylene glycol monomethyl ether acetate, 0.1-0.5% of a dehydrating agent, 0.1-0.5% of a defoaming agent, 0.3-3% of a leveling agent, 0.1-0.5% of an anti-sagging agent, 0.1-1% of an ultraviolet light absorber, 0.1-1% of an ultraviolet light stabilizer, 0.01-0.3% of a catalyst, and 0.3-0.8% of a dispersant.

[0044] The polyurethane curing agent comprises the following components: 50-80% of aliphatic isocyanate, 5-25% of n-butyl acetate, and 5-20% of propylene glycol monomethyl ether acetate;

[0045] The first diluent comprises the following components: 40-60% of n-butyl acetate, 20-40% of propylene glycol monomethyl ether acetate, and 5-25% of isoamyl acetate.

[0046] The mass ratio of the molding main agent, the polyurethane curing agent and the first diluent is (1-5):1:(0.1-1).

[0047] The castor oil modified short oil alkyd resin has a solid content of 60-80%, a hydroxyl value of 100-150 mg KOH / g, and a viscosity (25° C.) of 15,000-25,000 mPa·s. Preferably, the castor oil modified short oil alkyd resin is at least one of FX-6701 and FX-6703.

[0048] The solid content of the hydroxy acrylic resin is 70-85%, the hydroxy content is 2%-6%, and the viscosity (25° C.) is 2000-10000 mPa·s. Preferably, the hydroxy acrylic resin is at least one of Setalux 1903BA-75 and Setalux 1753SS-70.

[0049] The dehydrating agent is at least one of toluenesulfonic acid isocyanate and vinyltrimethoxysilane.

[0050] The defoaming agent is at least one of AX3301 and BYK-051.

[0051] The leveling agent is at least one of BYK-306 and BYK-310.

[0052] The anti-sagging agent is at least one of Sothix 250 and BYK430.

[0053] The ultraviolet light absorber is at least one of Tinuvin 328 and Tinuvin 900.

[0054] The ultraviolet light stabilizer is at least one of Tinuvin 292 and Tinuvin 249.

[0055] The catalyst is at least one of dibutyltin dilaurate, triethylenediamine and zinc isooctanoate.

[0056] Furthermore, the dispersant is one or both of KH560 and KH570.

[0057] Furthermore, the aliphatic isocyanate is hexamethylene diisocyanate trimer. Preferably, the specific model of the hexamethylene diisocyanate trimer is at least one of HT-100 and Coronate HXR.

[0058] To achieve the above-mentioned objectives, the present invention also provides a method for preparing the aforementioned decorative protective varnish, comprising the following steps: separately preparing a molding base, a polyurethane curing agent, and a first diluent, then uniformly mixing them in a mass ratio of molding base: polyurethane curing agent = (1-5):1, and finally adding the first diluent to adjust the viscosity to reach the construction viscosity, stirring evenly, and thus obtaining the decorative protective varnish.

[0059] Decorative protective varnish can be used as a protective layer for precious metal paint products, including the following steps:

[0060] S1, heating and stirring an organic resin and an organic solvent until fully dissolved to obtain an organic vehicle, adding the organic vehicle and a dispersant to the precious metal powder, stirring evenly, and finally adding a diluent and stirring evenly to obtain a precious metal paint;

[0061] S2, spray the precious metal paint on the surface of the substrate, dry it naturally or by heating, after the first coat of metallic paint is completely dry, spray the metallic paint again and dry it, finally spray the decorative protective varnish on the surface of the metallic paint, which will form a protective layer after drying.

[0062] Furthermore, the precious metal paint includes the following components: by mass fraction, 10-50% precious metal powder, 1-10% organic resin, 3-25% organic solvent, 0.3-1% dispersant, and 35-65% diluent.

[0063] Furthermore, the precious metal powder is in the shape of flakes, with a flake diameter of 5 to 30 μm and a thickness of 50 to 300 nm; the precious metal is one of gold and silver.

[0064] Furthermore, the organic resin is composed of one or more of cellulose acetate butyrate, ethyl cellulose, acrylic resin, and polyvinyl butyral.

[0065] The organic solvent consists of one of dimethyl adipate, alcohol ester dodecyl terpineol, terpineol, and one or more of diethylene glycol butyl ether acetate.

[0066] The diluent is at least one of camphor oil and isoamyl acetate.

[0067] The dispersant is at least one of KH550, KH560, and KH570.

[0068] The base material is wood, copper, aluminum, etc.

[0069] The preparation method of the decorative protective varnish provided by the present invention is described below with reference to specific examples. Unless otherwise specified, the raw materials and reagents in the examples of this application were purchased from commercial channels.

[0070] Examples 1-3 and Comparative Example 1

[0071] Examples 1-3 and Comparative Example 1 provide a precious metal paint, the raw material composition of which is shown in Table 1:

[0072] Table 1 Raw material composition of precious metal paint provided in Examples 1-3 and Comparative Example 1

[0073]

[0074]

[0075] The flake gold powder and the flake silver powder have a diameter of 5 to 30 μm and a thickness of 50 to 300 nm.

[0076] The preparation process of the precious metal paint of Examples 1-3 and Comparative Example 1 is as follows: the organic resin and the organic solvent are heated and stirred until fully dissolved to obtain an organic carrier, the organic carrier and the dispersant are added to the precious metal powder and stirred evenly, and finally the diluent is added and stirred evenly to obtain the precious metal paint.

[0077] Experiments show that the metallic paints prepared in Examples 1-3 can be directly sprayed and used, have good moldability, and have natural and beautiful colors.

[0078] The precious metal paints prepared in Examples 1-3 and Comparative Example 1 were subjected to performance tests, and the performance test results and standards are shown in the following table.

[0079] Table 2 Precious metal paint performance test results and standards

[0080]

[0081] The gold paint prepared in Comparative Example 1 has the same gold content and viscosity as the gold paint prepared in Example 1. After spraying twice on the substrate (made of aluminum), the brightness and color were tested using a spectrophotometer after drying. The results are shown in the following table.

[0082] Table 3 Spectrophotometer test results

[0083] Example 1 Comparative Example 1 <![CDATA[Brightness L * > 67.73 65.28 <![CDATA[Red a * > 9.24 10.66 Yellow b* 33.56 31.74

[0084] As can be seen from Table 3, the brightness of the gold paint of Comparative Example 1 is slightly worse, and the gold color is reddish.

[0085] Examples 4-6 and Comparative Example 2

[0086] Examples 4-6 and Comparative Example 2 provide a decorative protective varnish, the formulations of which are shown in Tables 4-7, respectively:

[0087] Table 4: Formulation of decorative protective varnish of Example 4

[0088]

[0089]

[0090] In Example 4, the molding base, polyurethane curing agent and diluent were prepared separately, and then mixed evenly at a mass ratio of molding base: polyurethane curing agent = 2:1, and then the diluent was added to a viscosity suitable for spraying (18-20 seconds / coating-4 cups, 25°C).

[0091] Table 5: Formulation of decorative protective varnish of Example 5

[0092]

[0093]

[0094]

[0095] In Example 5, the molding base, polyurethane curing agent and diluent were prepared separately, and then mixed evenly at a mass ratio of molding base: polyurethane curing agent = 2:1, and then the diluent was added to a viscosity suitable for spraying (18-20 seconds / coating-4 cups, 25°C).

[0096] Table 6 Formulation of decorative protective varnish of Example 6

[0097]

[0098]

[0099] In Example 6, the molding base, polyurethane curing agent and diluent were prepared separately, and then mixed evenly at a mass ratio of molding base: polyurethane curing agent = 2:1, and then the diluent was added to a viscosity suitable for spraying (18-20 seconds / coating-4 cups, 25°C).

[0100] Table 7 Formula of decorative protective varnish of Comparative Example 2

[0101]

[0102]

[0103]

[0104] In Comparative Example 2, the molding base, polyurethane curing agent and diluent were prepared separately, and then mixed evenly at a mass ratio of molding base: polyurethane curing agent = 2:1, and then the diluent was added to a viscosity suitable for spraying (18-20 seconds / coating-4 cups, 25°C).

[0105] In Comparative Example 2, hydroxy acrylic acid is used in place of castor oil-modified short oil alkyd resin in the mold-forming main agent to ensure that the resin solid content in the mold-forming main agent remains unchanged and the types of other components remain unchanged.

[0106] Experiments show that the decorative protective varnishes prepared in Examples 4-6 have good weather resistance, good fullness, fast drying speed, fine surface texture and natural gloss.

[0107] The decorative protective varnishes prepared in Examples 4-6 and Comparative Example 2 were subjected to performance tests. The performance test results and standards are shown in the following table.

[0108]

[0109]

[0110] The results show that the other properties of the protective varnish prepared in Comparative Example 2 are similar to those of the protective varnishes prepared in Examples 4-6, but the flexibility is slightly worse and the curing time is slightly longer.

[0111] The precious metal paint prepared in Example 1 is sprayed on the surface of the substrate (aluminum), and dried naturally or by heating. After the first coat of the metal paint is completely dried, the metal paint is sprayed again and dried. The actual picture is as follows: Figure 1 Then spray the decorative protective varnish prepared in Example 4 on the surface of the metallic paint, and a protective layer can be formed after drying, as shown in the actual figure. Figure 2 shown.

[0112] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A decorative protective varnish, characterized in that: The invention comprises a molding main agent, a polyurethane curing agent and a first diluent; the molding main agent comprises the following components by mass fraction: 50-85% of hydroxy acrylic resin, 10-30% of castor oil modified short oil alkyd resin, 1-10% of n-butyl acetate, 1-10% of propylene glycol monomethyl ether acetate, 0.1-0.5% of a dehydrating agent, 0.1-0.5% of a defoaming agent, 0.3-3% of a leveling agent, 0.1-0.5% of an anti-sagging agent, 0.1-1% of an ultraviolet absorber, 0.1-1% of an ultraviolet stabilizer, 0.01-0.3% of a catalyst, and 0.3-0.8% of a dispersant; The polyurethane curing agent comprises the following components: 50-80% aliphatic isocyanate, 5-25% n-butyl acetate, and 5-20% propylene glycol monomethyl ether acetate; The first diluent comprises the following components: 40-60% of n-butyl acetate, 20-40% of propylene glycol monomethyl ether acetate, and 5-25% of isoamyl acetate.

2. The decorative protective varnish according to claim 1, characterized in that: The mass ratio of the molding main agent, the polyurethane curing agent and the first diluent is (1-5):1:(0.1-1).

3. The decorative protective varnish according to claim 1, characterized in that: The castor oil-modified short oil alkyd resin has a solid content of 60-80%, a hydroxyl value of 100-150 mg KOH / g, and a viscosity of 15000-25000 mPa·s.

4. The decorative protective varnish according to claim 1, characterized in that: The solid content of the hydroxy acrylic resin is 70-85%, the hydroxy content is 2%-6%, and the viscosity is 2000-10000 mPa·s.

5. The decorative protective varnish according to claim 1, characterized in that: The dispersant is one or both of KH560 and KH570.

6. The decorative protective varnish according to claim 1, characterized in that: The aliphatic isocyanate is hexamethylene diisocyanate trimer.

7. A method for preparing the decorative protective varnish according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: preparing a molding main agent, a polyurethane curing agent and a first diluent respectively, then uniformly mixing the molding main agent: polyurethane curing agent in a mass ratio of (1-5):1, finally adding the first diluent to adjust the viscosity to reach the construction viscosity, and stirring evenly to obtain a decorative protective varnish.

8. Use of the decorative protective varnish according to any one of claims 1 to 6, characterized in that: The decorative protective varnish is used as a protective layer for precious metal paint products, comprising the following steps: S1, heating and stirring an organic resin and an organic solvent until fully dissolved to obtain an organic vehicle, adding the organic vehicle and a dispersant to the precious metal powder, stirring evenly, and finally adding a diluent and stirring evenly to obtain a precious metal paint; wherein, by mass fraction, the precious metal powder is 10-50%, the organic resin is 1-10%, the organic solvent is 3-25%, the dispersant is 0.3-1%, and the diluent is 35-65%; S2, spraying the precious metal paint on the surface of the substrate, drying naturally or by heating, after the first coat of metallic paint is completely dried, spraying the metallic paint again and drying, and finally spraying the decorative protective varnish on the surface of the metallic paint, which forms a protective layer after drying.

9. The use of the decorative protective varnish according to claim 8, characterized in that: The precious metal paint comprises the following components: the precious metal powder is flaky powder with a flake diameter of 5 to 30 μm and a thickness of 50 to 300 nm.

10. The use of the decorative protective varnish according to claim 9, characterized in that: The precious metal powder is one of gold powder and silver powder.

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