Water-based anti-scratch matt varnish for open coating

Abstract

The invention discloses a water-based scratch-resistant matt varnish for open coating. The water-based scratch-resistant matt varnish is prepared from main paint, a curing agent and water in a mass ratio of 100: (9-12): (10-5), (1) the main paint comprises the following components in percentage by weight: 5-30% of water-based hydroxyl acrylic emulsion and 20-60% of water-based matting emulsion; 1%-5% of matting powder; the anti-scratch coating is prepared from the following components in percentage by weight: 0.3%-0.4% of a defoaming agent, 0.5%-1.5% of a wetting agent, 4.0%-5.0% of a film-forming solvent, 25%-45% of deionized water, 0.5%-1.0% of a rheological additive and 0.5%-2.0% of an anti-scratch additive. And (2) the curing agent comprises the following components in percentage by weight: 60.0%-100% of HDI (hexamethylene diisocyanate) water dispersible isocyanate and 0%-40.0% of propylene glycol methyl ether acetate. The product provided by the invention has the advantages of no light, no bright mark, good opening effect, no phenomena of bloated conduit, accumulation and non-uniform gloss, and is especially suitable for spraying construction of an automatic spraying line.

Description

Technical Field

[0001] The invention belongs to the field of water-based wood coatings, and in particular relates to a water-based scratch-resistant matte clear topcoat for open coating and a preparation method thereof. Background Art

[0002] As environmental protection and health awareness grows, water-based wood paint has become an ideal choice for furniture manufacturing due to its low VOC content, environmental protection, non-toxicity, and easy cleaning. Water-based wood paint can not only reduce the impact on the environment and human health, but also provide good adhesion and durability, protecting wood from damage such as moisture and insect pests.

[0003] In the field of furniture design and manufacturing, furniture with open coating effects is gradually becoming a trend. It can not only show the natural beauty of wood and meet consumers' demand for natural, environmentally friendly and personalized products, but also bring a unique visual effect and tactile experience to furniture, providing new market opportunities for furniture manufacturers. In recent years, it has been increasingly favored by consumers. As consumers' requirements for furniture's environmental performance and aesthetics continue to increase, it is expected that furniture with open coating effects will occupy a more important position in the future market.

[0004] The open coating effect is to retain the natural texture and pores of the wood when coating the furniture surface, so that the furniture surface presents a natural texture and a three-dimensional, rustic effect. The open coating method is suitable for high-grade wood with deep ducts and obvious textures, such as oak and ash. In contrast, closed paint will completely cover the texture of the wood, making the furniture surface appear smooth and flat.

[0005] In actual construction operations, due to the amount of coating applied by workers during spraying, it is easy to cause the open effect to become a semi-open or closed effect, and the edge of the duct will be bloated, piled up, and have uneven gloss. It is necessary to develop an open clear topcoat that is insensitive to the amount of coating applied and has uniform gloss.

[0006] Achieving an ultra-matte or completely matte effect is also a major challenge. Currently, many water-based clear topcoats have difficulty controlling the gloss below 4 degrees. In addition to ensuring low gloss (gloss below 2 degrees), matte clear topcoats must also have good scratch resistance (no bright marks when scratched) to meet the wear resistance requirements of daily furniture use. However, the improvement of scratch resistance is often in conflict with the reduction of gloss, which is also a problem that the industry urgently needs to solve.

[0007] Patent document CN102391769A discloses a PU yellowing-resistant quick-drying open clear topcoat, comprising a main paint and a curing agent in a weight ratio of (20-30): (15-25); the main paint comprises a hydroxy acrylic resin and a chloroacetic resin having a repeating unit of the structural formula (I), the content of the hydroxy acrylic resin is 15-25wt%; the content of the chloroacetic resin is 8-15wt%; the curing agent comprises a trimer of HDI and TDI in a mass ratio of (15-20): (20-25); the chlorinated wax resin is a copolymer of vinyl chloride and vinyl acetate, obtained by copolymerizing vinyl chloride monomer and vinyl acetate under the action of an initiator. The spraying amount is 40-70g / m 2 , the surface drying time is 5 to 10 minutes and the actual drying time is 2 hours. However, the glossiness of the document is relatively high and cannot meet the requirement of glossiness below 4 degrees.

[0008] Patent document CN102391769A discloses a smoked wood two-component matte clear topcoat coating and its preparation method, which is composed of component A and component B with a weight ratio of 1: (0.2-0.3); component A is: 30%-40% of clean resin, 15%-20% of nitrocellulose, 1.5%-2.5% of epoxy plasticizer, 3%-5% of polymethyl methacrylate urea resin, etc.; component B is: 40%-60% of hexamethylene diisocyanate trimer, 40%-60% of n-butyl acetate; the clean resin is an oil-free saturated polyester resin. However, the document uses nitrocellulose and epoxy plasticizer, which does not conform to the development trend of green environmental protection, and its glossiness is relatively high (above 12 degrees), which cannot meet the requirement of glossiness below 4 degrees.

[0009] Patent document CN112646467A discloses a wear-resistant, highly transparent and super-smooth PU open matte clear topcoat, wherein the mass ratio of component A to component B is 10:(5-6); component A comprises: 35-55% hydroxy acrylic resin, 0.5-1% wetting dispersant, 0.5-1.5% polyamide anti-settling slurry, 0.1-0.5% antioxidant, 0.3-0.5% ultraviolet light absorber, 5-8% aldehyde-ketone resin %, wax powder 0.5-3%, glass powder 3-5%, matting powder 2-3.5%, cellulose acetate butyrate 18-28%, ether ester solvents 5-10%, ester solvents 1-5%, defoaming agent 0.1%-0.5%, leveling agent 0.55%-1.6%, drying agent 0.05-0.1%; component B: n-butyl acetate 25-45%, dehydrating agent 0.1-0.3%, aromatic polyisocyanate TDI 20-50%, aliphatic polyisocyanate HDI 10-20%; the fineness of the hydroxylated acrylic resin is 3-10μm, the viscosity is 2500-5000CPS, and the hydroxyl value is 2-3.5. However, the document states that the hydroxy acrylic resin requires a large amount of solvents such as 25-45% n-butyl acetate as a diluent, and the VOC emissions are much higher than those of water-based products. Later use requires auxiliary environmental protection adsorption conversion equipment, which is not in line with the national environmental protection policy of energy conservation and emission reduction and the use of low-VOC products; the gloss of PU open matte clear topcoat is around 30 degrees, which is also called matte, but it does not meet the gloss of less than 4 degrees required by this patent. Summary of the invention

[0010] The purpose of the present invention is to provide a water-based scratch-resistant matte clear topcoat for open coating and a preparation method thereof, so as to solve the technical problem in the prior art that it is difficult to take into account the performance of good opening effect, uniform gloss, gloss below 4 degrees and scratch resistance without bright marks.

[0011] The water-based anti-scratch matte clear topcoat for open coating of the present invention is characterized by comprising a main paint, a curing agent and water in a mass ratio of 100:(9-12):(10-5);

[0012] (1) The main paint comprises the following raw materials in mass fractions: water-based hydroxy acrylic emulsion: 5% to 30%, water-based matting emulsion: 20% to 60%; matting powder: 1% to 5%; defoaming agent: 0.3% to 0.4%, wetting agent: 0.5% to 1.5%, film-forming solvent: 4.0% to 5.0%, deionized water: 25% to 45%, rheological additive: 0.5% to 1.0%, anti-scratch additive: 0.5% to 2.0%;

[0013] (2) The curing agent comprises the following raw materials in mass fractions: HDI water-dispersible isocyanate: 60.0% to 100%, propylene glycol methyl ether acetate: 0% to 40.0%;

[0014] The water-based hydroxyl acrylic emulsion is a low-hydroxyl acrylic polymer with a mass solid content of 35% to 45%, a mass content of hydroxyl of 1.2% to 1.7%, a molecular weight of 300,000 to 600,000, and a viscosity of 100 to 3000 mPa.s; for example: S5580 of Zhanchen New Materials has a hydroxyl content of 1.6% and a viscosity of 2000 mPa.s, and has the advantages of good film-forming properties, transparency, easy matting, and high hardness, and is suitable for anti-scratch systems; the hydroxyl content has an important influence on the cross-linking density of the emulsion, the final physical and chemical properties of the coating, and the reaction with other components; the continuous increase of the hydroxyl content within a certain range can increase the cross-linking density of the coating, thereby improving the hardness, wear resistance, water resistance and chemical resistance of the coating, but it will also reduce the flexibility and glossiness of the coating;

[0015] The aqueous matte emulsion is a hydroxyl-containing aqueous polyurethane acrylic copolymer dispersion with a mass solid content of 30% to 35%, a molecular weight of 500,000 to 800,000, and a viscosity of 100 to 2000 mPa.s; for example: D1103 of honeycomb nanomaterials, with a hydroxyl content of 1.4%, has excellent transparency, low gloss, and a delicate and smooth feel with a skin-like effect;

[0016] The matting powder is fumed silica without surface treatment, with an average particle size of 9.5 μm, preferably TS-100 matting powder produced by Evonik, which has high oil absorption and matting efficiency and can reduce finger scratch marks;

[0017] The defoamer is one or more of polyether or fluorine-modified silicone surfactants, such as TEGO810 from Digo and BYK022 from German BYK.

[0018] The wetting agent is an organic siloxane twin structure surfactant and / or a polyether modified polydimethylsiloxane, such as TWIN 4100 of Digo;

[0019] The membrane-forming solvent is at least one of dipropylene glycol butyl ether (DPNB), dipropylene glycol methyl ether (DPM), ethylene glycol butyl ether (BCS), and dimethyl nylonate (DBE);

[0020] The rheological additive is a polyether polyurethane rheological additive, such as Hemmings medium and low shear thickener FX1010 and R299, which can improve the opening effect of the product and achieve the best rheological state;

[0021] The anti-scratch agent is an ultra-high molecular weight polydimethylsiloxane dispersion, such as Dow's 211S;

[0022] The HDI water-dispersible isocyanate is an isocyanate with the brand name XP2655 produced by Covestro, or a water-based curing agent prepared by the method disclosed in U.S. Patent Document US20040034162A1, such as ZWH9988 of Zhanchen New Materials.

[0023] The method for preparing a water-based anti-scratch matte clear topcoat for open coating of the present invention is characterized by comprising the following steps:

[0024] (1) Add the aqueous hydroxy acrylic emulsion and the aqueous matting emulsion into a preparation tank, add the matting powder, defoaming agent and wetting agent at a rate of 600 to 800 r / min, and disperse at a rate of 800 to 1200 r / min until there is no shrinkage hole on the scraper and the fineness is ≤30 μm; then add the mixture of the film-forming aid and water at a rate of 600 to 800 r / min, and continue to disperse for 10 to 20 minutes; then add most of the rheological aid, and disperse at a rate of 1000 to 2000 r / min until the fineness is ≤30 μm without oil shrinkage; finally, add the anti-scratch aid and the remaining water at a rate of 800 to 1500 r / min, adjust the viscosity with the remaining rheological aid, and disperse until the fineness is ≤30 μm without oil shrinkage to obtain the main agent;

[0025] (2) mixing the curing agent according to the raw material ratio and stirring evenly;

[0026] (3) First, mix the main agent and curing agent and stir them evenly, then add water to adjust the viscosity before construction.

[0027] The viscosity requirement of the main paint is 70-90s for applying 4 cups at 25°C, the pH value is 8.0-9.0, the construction method is to adjust the viscosity to 50±3S by automatic line spraying or manual spraying with a W71 gun, the coating amount is 50-100g / ㎡, and the material construction effect is an open effect.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention adopts hydroxy acrylic resin as a film-forming substance to improve the hardness and yellowing resistance of the paint film, and can significantly improve the permeability of the paint film when used with an aqueous matting emulsion. The paint film is easy to matt, and can achieve the characteristics of low gloss, easy matting, no bloating or blooming in the open effect, uniform gloss, and low scratch marks; the design of low solid content (≤22%) also avoids the shortcomings of bloating and blooming of the catheter that are generally present in existing open effect products; in particular, matting powder, matting powders of various oil absorption amounts such as gas phase method and precipitation method are tested, and Evonik's TS-100 matting powder is selected, which is composed of unsurface-treated silicon dioxide, has the functions of matting, anti-settling, and providing a pseudo-thick rheological state, and is of great help to the open pore effect and anti-scratch and non-shiny.

[0030] The product of the present invention not only has the basic performance requirements of open effect, scratch resistance, high transparency and the like required by water-based open clear topcoat, but also can pass the requirements of regulatory standards such as GB 18581-2020, ASTM F963, EN 71-3, PAHS, and REACH in terms of its environmental performance.

[0031] The product of the present invention has the advantages of being matte, free of bright marks from scratches, having a good opening effect, naturally fitting on the material, and having no bloated tubes, accumulation, or uneven gloss. It is particularly suitable for spraying construction on an automatic spray line, is easy to control the coating amount, and exhibits a better opening effect.

[0032] The product of the present invention can be directly sprayed on logs such as oak, black walnut, mahogany, and merlot, as well as deep-duct materials for veneer, and can be used for coating the surfaces of wooden articles, furniture, floors, etc., to provide protection and decorative effects to prevent scratches and other surface damage, while maintaining the natural open texture and color of the wood. The matte gloss effect can achieve a woodworking artistic conception where the wood is visible but not the paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a comparison of the coating films after painting with matting powder and matting emulsion under an electron microscope. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0035] The raw materials in this embodiment are all commercially available products.

[0036] Example 1

[0037] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0038] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0039] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0040] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0041] Table 1 Raw materials and component mass fractions of Examples 1 to 6 and Comparative Examples 1 to 2

[0042]

[0043] Example 2

[0044] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0045] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0046] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0047] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0048] Example 3

[0049] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0050] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0051] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0052] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0053] Example 4

[0054] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0055] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0056] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0057] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0058] Example 5

[0059] A water-based scratch-resistant matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1.

[0060] The main paint is prepared by the following steps:

[0061] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0062] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0063] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0064] Example 6

[0065] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0066] (1) Add water-based hydroxy acrylic emulsion S5580 and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoamer TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0067] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0068] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:8:5, and spray on the oak board according to the coating amount of 70g / ㎡.

[0069] Example 7

[0070] A water-based scratch-resistant matte clear topcoat for open coating, the formula and preparation method are the same as those of Example 1, but at room temperature of 30°C and room humidity of 50%, the viscosity is adjusted to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and the coating amount is 100g / ㎡ and sprayed on an oak board for construction.

[0071] Comparative Example 1

[0072] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0073] (1) Add water-based high-hydroxy acrylic emulsion S7801 (produced by Zhanchen New Materials Co., Ltd., with a hydroxyl content of 3.2%) and water-based matting emulsion D1103 into the preparation tank, and add matting powder TS100, defoaming agent TEGO810, and wetting agent TWIN at a rate of 600-800 r / min. 4100, dispersed at a rate of 800-1200r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30μm; then add a mixture of film-forming additives DPM, DPNB and water at a rate of 600-800r / min, and continue to disperse for 10-20min; then add most of the rheological additive R299, dispersed at a rate of 1000-2000r / min until the fineness is ≤30μm without oil shrinkage; finally, add the anti-scratch additive 211S and the remaining water at a rate of 800-1500r / min, adjust the viscosity with the remaining rheological additive R299, dispersed to a fineness of ≤30μm without oil shrinkage, and obtain the main agent;

[0074] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0075] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0076] Comparative Example 2

[0077] A water-based anti-scratch matte clear topcoat for open coating, the raw materials and component mass fractions of which are listed in Table 1. The main paint is prepared by the following steps:

[0078] (1) Add water-based hydroxy acrylic emulsion S5580 into a preparation tank, add matting agent TS100, defoaming agent TEGO810, and wetting agent TWIN 4100 at a rate of 600 to 800 r / min, and disperse at a rate of 800 to 1200 r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30 μm; then add a mixture of film-forming aids DPM, DPNB and water at a rate of 600 to 800 r / min, and continue to disperse for 10 to 20 minutes; then add most of the rheological additive R299, and disperse at a rate of 1000 to 2000 r / min until the fineness is ≤30 μm without oil shrinkage; finally, add anti-scratch additive 211S and the remaining water at a rate of 800 to 1500 r / min, adjust the viscosity with the remaining rheological additive R299, and disperse until the fineness is ≤30 μm without oil shrinkage to obtain the main agent;

[0079] (2) adding the curing agent in the amount of 60.0% HDI water dispersible isocyanate and 40.0% propylene glycol methyl ether acetate and stirring evenly;

[0080] At room temperature of 30℃ and humidity of 50%, adjust the viscosity to 50±5″ according to the ratio of main paint: curing agent: water = 100:10:10, and spray on the oak board according to the coating amount of 70g / ㎡.

[0081] Comparative Example 3

[0082] Competitor Carpoly's water-based two-component open clear topcoat was sprayed on oak boards at a coating amount of 70g / ㎡ at room temperature of 30°C and 50% humidity.

[0083] Comparative Example 4

[0084] The competitor's Volanta water-based two-component open clear topcoat was sprayed on oak boards at a coating amount of 70g / ㎡ at room temperature of 30°C and 50% humidity.

[0085] Examples 1 to 6 and Comparative Examples 1 to 4 were tested according to the commonly used test items for water-based open clear topcoat. The results are shown in Table 2.

[0086] See attached Figure 1 The electron microscope images of the matting resin and matting powder film formation show that the water-based matting emulsion (D1103) used in the present invention has a better matting effect than the matting powder (fumed silica). The more D1103 is added, the lower the glossiness. However, its matting effect also has a limit, and it still needs to be combined with the matting powder to achieve the most matte effect. The matting effect is also related to the surface roughness of the substrate. The higher the roughness of the substrate surface, the lower the glossiness. When the surface roughness of the substrate is the same, the glossiness can be further reduced by using the complementarity of the matting powder and the matting emulsion.

[0087] Comparing Example 1 with Example 6, when the amount of water-based matting emulsion (D1103) added is the same, the gloss is significantly increased after the matting powder TS100 is reduced. Compared with Example 1, Comparative Example 1 uses water-based high-hydroxy acrylic emulsion S7801, and the gloss is also significantly increased. This is because the high-hydroxyl water-based emulsion needs to react with more curing agents (-OH and -NCO reaction), which will lead to higher gloss and cannot achieve a matte effect. At present, the bright products on the market are all prepared with high-hydroxyl emulsions (hydroxyl content ≥ 3.2). Comparative Example 2 did not add matting emulsion D1103. With the same addition of 5% matting powder, the gloss increased to 10 degrees, indicating that the low-hydroxyl emulsion, matting emulsion and matting powder need to be reasonably matched to achieve the best matting effect.

[0088] Table 2 Related performance test results of Examples 1 to 8 and Comparative Examples 1 to 2

[0089]

[0090]

[0091] Compared with the commercially available comparative examples 3 and 4, the surface opening effect of Examples 1 to 7 is flawless, not bloated, the conduits are natural, the gloss can be extremely low matte, more transparent, higher hardness, and the scratch marks are lighter. The gloss of Example 5 can be as low as 0.5 degrees, achieving a matte and scratch-resistant effect.

[0092] The formula and preparation method of Example 1 and Example 7 are exactly the same, and the only difference is the coating amount of 70g / ㎡ and the coating amount of 100g / ㎡. It can be seen from Table 2 that the open spraying effect of Example 1 and Example 7 is basically the same, the catheter is not bloated, the gloss is uniform, and the paint film collapses naturally.

[0093] The product of the present invention can meet the decorative effect of water-based paint on furniture, beautify the wood grain of the material, and provide a good solution to the anti-scratch problem that terminal customers are concerned about. It has obvious performance advantages and broad market prospects.

Claims

1. A water-based anti-scratch matte clear topcoat for open painting, characterized in that: It is composed of a main paint, a curing agent and water in a mass ratio of 100: (9-12): (10-5); (1) The main paint comprises the following raw materials in mass fractions: water-based hydroxy acrylic emulsion: 5% to 30%, water-based matting emulsion: 20% to 60%; matting powder: 1% to 5%; Defoaming agent: 0.3%~0.4%, wetting agent: 0.5%~1.5%, film-forming solvent: 4.0%~5.0%, deionized water: 25%~45%, rheological additive: 0.5%~1.0%, anti-scratch additive: 0.5%~2.0%; (2) The curing agent comprises the following raw materials in mass fractions: HDI water-dispersible isocyanate: 60.0% to 100%, propylene glycol methyl ether acetate: 0% to 40.0%.

2. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The water-based hydroxyl acrylic emulsion is a low-hydroxyl acrylic polymer with a mass solid content of 35% to 45% and a mass hydroxyl content of 1.2% to 1.7%, a molecular weight of 300,000 to 600,000, and a viscosity of 100 to 3000 mPa.s.

3. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The aqueous matte emulsion is a hydroxyl-containing aqueous polyurethane acrylic copolymer dispersion with a mass solid content of 30% to 35%, a molecular weight of 500,000 to 800,000, and a viscosity of 100 to 2000 mPa.s.

4. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The matting powder is fumed silica without surface treatment, and has an average particle size of 9.5 μm.

5. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The defoaming agent is one or more of the organic silicon surfactants modified with polyether or fluorine; the wetting agent is an organic siloxane twin structure surfactant and / or polyether modified polydimethylsiloxane.

6. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The film-forming solvent is at least one of dipropylene glycol butyl ether, dipropylene glycol methyl ether, ethylene glycol butyl ether and nylon acid dimethyl ester.

7. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The rheological additive is a polyether polyurethane rheological additive; and the anti-scratch additive is an ultra-high molecular weight polydimethylsiloxane dispersion.

8. The water-based scratch-resistant matte clear topcoat according to claim 1, characterized in that: The HDI water-dispersible isocyanate is an isocyanate with a brand name of XP2655 produced by Covestro, or a water-based curing agent prepared by the method disclosed in US Pat. No. US20040034162A1.

9. The method for preparing the water-based scratch-resistant matte clear topcoat according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Add the aqueous hydroxy acrylic emulsion and aqueous matting emulsion into a preparation tank, add the matting powder, defoaming agent and wetting agent at a rate of 600 to 800 r / min, and disperse at a rate of 800 to 1200 r / min until there is no shrinkage cavity on the scraper and the fineness is ≤30 μm; then add the mixture of the film-forming aid and water at a rate of 600 to 800 r / min, and continue to disperse for 10 to 20 minutes; then add most of the rheological aid, and disperse at a rate of 1000 to 2000 r / min until the fineness is ≤30 μm without oil shrinkage; finally, add the anti-scratch aid and the remaining water at a rate of 800 to 1500 r / min, adjust the viscosity with the remaining rheological aid, and disperse until the fineness is ≤30 μm without oil shrinkage to obtain the main agent; (2) Mixing the curing agent according to the raw material ratio and stirring evenly; (3) First, mix the main agent and curing agent and stir them evenly, then add water to adjust the viscosity before construction.

10. The water-based scratch-resistant matte clear topcoat according to any one of claims 1 to 6, characterized in that: The viscosity requirement of the main paint is 70-90s for applying 4 cups at 25°C, the pH value is 8.0-9.0, the construction method is to adjust the viscosity to 50±3S by automatic line spraying or manual spraying with a W71 gun, the coating amount is 50-100g / ㎡, and the material construction effect is an open effect.

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