A connecting layer composition for colorful paint and its preparation method and application

Abstract

The present invention discloses a connecting layer composition for colorful paint, and its preparation method and application. The connecting layer composition includes a first component and a second component; the first component includes a water-based hydroxypropylene resin, a modified high surface tension hydroxypropylene resin, a directional additive, a first cosolvent, an additive, a colorful powder, water, and a rheological additive that may or may not be used; the second component includes a water-based curing agent and a second cosolvent; wherein the modified high surface tension hydroxypropylene resin is prepared by reacting a hydroxy acrylic emulsion containing a carboxyl functional group, an MAH-modified EPE type block polyether resin, and hydrophilic fumed silica. The connecting layer composition provided by the present invention can achieve rapid spreading on the surface of a water-based varnish, good leveling and pigment orientation, while ensuring good adhesion between coatings and bubble-free film thickness, thereby ensuring the excellent appearance of the matching coating; at the same time, the connecting layer composition of the present invention has good application prospects in the field of rail transit decoration.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating materials, and in particular relates to a connecting layer composition for colorful paint, a preparation method and an application thereof. Background Art

[0002] With the rapid development of my country's high-speed railways, the application of decorative coating materials in rail transit has become increasingly important. Water-based chromatic aqua paint, an environmentally friendly coating with unique visual effects, has gained popularity due to its unique angular color shifting phenomenon—displaying different colors depending on the viewing angle. This characteristic significantly enhances the visual dynamic effect, leading to its widespread application in the exterior coatings of new EMUs.

[0003] However, there have always been application difficulties in the application process of colorful paint. Especially under fast-paced construction conditions, the coating is easily affected by the construction environment, resulting in problems such as loss of gloss, orange peel, large waves, and low brightness. For example, when the humidity is high in spring and autumn, when water-based colorful paint is sprayed on the water-based PU base paint, and then water-based varnish is sprayed after a certain interval, due to the high humidity and low temperature, the surface of the paint film is not fully dried, and the surface tension is low, which makes it difficult to wet the varnish, and then produces problems such as poor leveling and large ripples. In addition, for large-area spraying on the outer surface of the motor vehicle, since the colorful layer is thin (about 5 microns), a single spray is prone to local unevenness, thinness to form paint particles, or thickness resulting in slow surface drying, which in turn causes problems such as poor leveling, blistering and loss of gloss in the varnish coating. Summary of the Invention

[0004] The main purpose of the present invention is to provide a connecting layer composition for colorful paint and its preparation method and application, so as to overcome the shortcomings of the prior art.

[0005] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0006] An embodiment of the present invention provides a connecting layer composition for a colorful paint, comprising a first component and a second component; the first component comprises a water-based hydroxypropylene resin, a modified high-surface-tension hydroxypropylene resin, a directional additive, a first cosolvent, an additive, a colorful powder, water, and a rheological additive that may or may not be used; the second component comprises a water-based curing agent and a second cosolvent;

[0007] The modified high surface tension hydroxypropylene resin is prepared by reacting a hydroxy acrylic emulsion containing a carboxyl functional group, an MAH-modified EPE type block polyether resin, and hydrophilic fumed silica.

[0008] An embodiment of the present invention further provides a method for preparing the aforementioned connecting layer composition for colorful paint, which comprises:

[0009] Evenly mixing a water-based hydroxypropyl resin, a modified high surface tension hydroxypropyl resin, a directional additive, a first cosolvent, an additive, a dazzling powder, water, and a rheological additive used or not to obtain a first component;

[0010] Furthermore, the aqueous curing agent and the second cosolvent are evenly mixed to obtain a second component, thereby obtaining a connecting layer composition for colorful paint.

[0011] The embodiments of the present invention also provide the use of the aforementioned connecting layer composition for colorful paint in the field of rail transit coating decoration.

[0012] An embodiment of the present invention also provides a colorful composite coating for the outer shell of an EMU, which includes: a connecting layer with special decorative and functional effects connecting the primer layer and the varnish layer, or connecting the topcoat layer and the varnish layer; wherein the connecting layer is formed by the aforementioned connecting layer composition for colorful paint.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) When the tie layer composition provided by the present invention is used in conjunction with a water-based PU basecoat / topcoat and a water-based PU clearcoat, it achieves rapid spreading, good leveling and pigment orientation on the surface of the water-based clearcoat while ensuring good adhesion and bubble-free film thickness between the coatings, thereby ensuring an excellent appearance of the matching coatings;

[0015] (2) The connecting layer composition of the present invention is not only suitable for colorful coatings for rail transit, but also has broad market application prospects, and will bring new breakthroughs to coating decorative materials in the rail transit field. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 Shown is a surface effect diagram coated with the composite coating in Comparative Example 1;

[0018] Figure 2 The figure shows the surface effect of the composite coating in Example 1. DETAILED DESCRIPTION

[0019] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. The solution of the present invention aims to achieve rapid spreading, good leveling and pigment orientation while ensuring good adhesion and bubble-free film thickness between coatings, thereby ensuring the excellent appearance of the matching coating. The connecting layer composition of the present invention is not only suitable for colorful coatings for rail transit, but also has broad market application prospects, and will bring new breakthroughs to coating decorative materials in the rail transit field.

[0020] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Specifically, as one aspect of the technical solution of the present invention, a connecting layer composition for a colorful paint includes a first component and a second component; the first component includes a water-based hydroxypropyl resin, a modified high surface tension hydroxypropyl resin, a directional additive, a first cosolvent, an additive, a colorful powder, water, and a rheological additive that may or may not be used; the second component includes a water-based curing agent and a second cosolvent;

[0022] The modified high surface tension hydroxypropylene resin is prepared by reacting a hydroxy acrylic emulsion containing a carboxyl functional group, an MAH-modified EPE type block polyether resin, and hydrophilic fumed silica.

[0023] In some preferred embodiments, the first component includes the following components calculated in parts by weight: 65-75 parts of water-based hydroxypropylene resin, 10-20 parts of modified high surface tension hydroxypropylene resin, 2-5 parts of directional additive, 4-8 parts of first cosolvent, 2-3 parts of additive, 0.3-5 parts of colorful powder, 8-14 parts of water and 0-0.5 parts of rheological additive.

[0024] In some preferred embodiments, the second component includes the following components calculated in parts by weight: 70-90 parts of a water-based curing agent and 10-30 parts of a second co-solvent.

[0025] In some preferred embodiments, the mass ratio of the first component to the second component is 10:1 to 1.5.

[0026] In some preferred embodiments, the tie layer composition further comprises a third component.

[0027] Furthermore, the third component includes water, but is not limited thereto.

[0028] Furthermore, the mass ratio of the first component, the second component and the third component is 10:1-1.5:2-4.

[0029] In some preferred embodiments, the method for preparing the modified high surface tension hydroxypropylene resin comprises:

[0030] A mixed reaction system comprising an EPE-type block polyether, maleic anhydride, dicumyl peroxide, and a solvent is subjected to a grafting reaction at 160-180° C. for 3-5 hours, followed by post-treatment to obtain an MAH-modified EPE-type block polyether resin;

[0031] Furthermore, the MAH-modified EPE type block polyether resin is mixed with a hydroxy acrylic emulsion containing a carboxyl functional group and hydrophilic fumed silica to prepare a modified high surface tension hydroxy acrylic resin.

[0032] Furthermore, the mixing reaction includes: mixing a carboxyl-functional hydroxyl acrylic emulsion with an MAH-modified EPE-type block polyether resin and aqueous fumed silica in sequence at room temperature to slightly above room temperature (e.g., 20°C to 45°C), and then dispersing the mixture at a speed of 1000-1500 rpm for 20-25 minutes to produce a modified high-surface-tension hydroxyl acrylic resin. This resin has a high surface tension, which facilitates the rapid spreading of the next clear coat, thereby achieving a "mirror effect." The aqueous fumed silica accelerates the surface migration of the resin and also increases its surface tension.

[0033] Furthermore, the EPE type block polyether is an EPE type block polyether with a high ethylene oxide structure content, and the molar ratio of ethylene oxide to propylene oxide structures in the EPE type block polyether is greater than 1.5.

[0034] Furthermore, the EPE type block polyether is a high EO content EPE type block polyether, and the high EO content in the EPE type block polyether is that the ratio of EO (ethylene oxide) to PO (propylene oxide) reaches 1.5:1 or higher.

[0035] Furthermore, the weight average molecular weight of the EPE type block polyether is 2000-3000.

[0036] Furthermore, the solvent includes any one or more combinations of N-methylpyrrolidone (NMP) and dimethyl sulfoxide (DMSO), but is not limited thereto.

[0037] Furthermore, the carboxyl functional group-containing hydroxy acrylic emulsion is a core-shell polyacrylate emulsion, the surface layer of which contains a large number of carboxyl groups (-COOH), and the hydroxyl content thereof is 1.0-1.4% based on the solid content.

[0038] Furthermore, the carboxyl functional group-containing hydroxyl acrylic emulsion is a core-shell polyacrylate emulsion, and the hydroxyl content of the core-shell polyacrylate emulsion is 1.0-1.4% based on solid content.

[0039] Furthermore, the hydrophilic fumed silica includes any one of American Cabot CABOT fumed silica M-5, Evonik silica AEROSIL380, and Huifu fumed silica HL-380, but is not limited thereto.

[0040] Furthermore, the mass ratio of the EPE type block polyether, maleic anhydride, dicumyl peroxide and solvent is 100:2.5-3.2:0.2-0.3:0-2.

[0041] Furthermore, the mass ratio of the carboxyl functional group-containing hydroxy acrylic emulsion, the MAH-modified EPE type block polyether resin and the hydrophilic fumed silica is 70-80:10-20:5-10.

[0042] Furthermore, the preparation method of the MAH-modified EPE-type block polyether resin includes: dissolving the EPE-type block polyether in a solvent to form a uniform solution, and gradually adding an initiator to the EPE-type block polyether solution under stirring. At an appropriate temperature, maleic anhydride is gradually added to the solution to ensure thorough mixing with the EPE-type block polyether. The grafting reaction is carried out under controlled temperature and stirring speed, the reaction temperature is generally between 160°C and 180°C, and the reaction time is between 3 and 5 hours. After the reaction is completed, unreacted raw materials and by-products are removed by filtering, washing, drying, and other steps to produce the MAH-modified EPE-type block polyether resin.

[0043] In some preferred embodiments, the aqueous hydroxypropylene resin includes an aqueous hydroxypropylene emulsion and / or an aqueous hydroxypropylene dispersion, such as Matsuo A12G (hydroxyl content based on solids is 1.2%, non-volatile matter is 45%), Matsuo A20G (hydroxyl content based on solids is 2.0%, non-volatile matter is 45%).

[0044] In some preferred embodiments, the hydroxyl value content of the water-based hydroxypropylene resin is 1.2 to 3.2 wt %.

[0045] In some preferred embodiments, the weight average molecular weight of the modified high surface tension hydroxypropylene resin is 100,000-200,000.

[0046] In some preferred embodiments, the hydroxyl value content of the modified high surface tension hydroxypropylene resin is 1.0 to 1.4 wt %.

[0047] In some preferred embodiments, the directional aid includes non-ionic modified ethylene-vinyl acetate copolymer wax emulsion (such as BYK8421) and / or polyamide wax (such as Fenghong PA-670, Zhuhai Yiwan New Materials YW-5303), but is not limited thereto.

[0048] In some preferred embodiments, the first co-solvent includes any one or more combinations of propylene glycol methyl ether (PM), n-butanol (NBA), dipropylene glycol butyl ether (DPnB), isopropyl alcohol (IPA), ethylene glycol butyl ether (BCS), diethylene glycol butyl ether (DBG), propylene glycol butyl ether (PnB), and dipropylene glycol methyl ether (DPM), and is not limited thereto.

[0049] In some preferred embodiments, the auxiliary agent includes any one or more combinations of defoaming agents, leveling agents, and wetting agents, but is not limited thereto.

[0050] In some preferred embodiments, the colorful powder includes any one or more combinations of laser powder, pearl powder, and chameleon pigment (displaying different color changes at different angles and different light conditions), and is not limited thereto.

[0051] In some preferred embodiments, the rheological additive includes any one or more combinations of Hemmings 299 polyurethane associative thickener, RM-805 of Green Union (Jining) Chemical, Guangzhou Hongxin Chemical 5006, Anhui Yuanchen New Materials YC-101, and Dow's 12W, and is not limited thereto.

[0052] In some preferred embodiments, the aqueous curing agent includes a water-dispersible isocyanate curing agent, but is not limited thereto.

[0053] Furthermore, the NCO content of the water-dispersible isocyanate curing agent is 19-23 wt %.

[0054] Furthermore, the solid content of the water-dispersible isocyanate curing agent is 98-100 wt %.

[0055] Furthermore, the viscosity of the water-dispersible isocyanate curing agent at 25° C. is 500-6500 mPa·s.

[0056] In some preferred embodiments, the second co-solvent includes propylene glycol methyl ether acetate (PMA) and / or propylene glycol diacetate (PGDA), but is not limited thereto.

[0057] Another aspect of the embodiments of the present invention further provides a method for preparing the aforementioned connecting layer composition for colorful paint, which comprises:

[0058] Evenly mixing a water-based hydroxypropyl resin, a modified high surface tension hydroxypropyl resin, a directional additive, a first cosolvent, an additive, a dazzling powder, water, and a rheological additive used or not to obtain a first component;

[0059] Furthermore, the aqueous curing agent and the second cosolvent are evenly mixed to obtain a second component, thereby obtaining a connecting layer composition for colorful paint.

[0060] Another aspect of the embodiments of the present invention further provides use of the aforementioned connecting layer composition for colorful paint in the field of rail transit coating decoration.

[0061] Another aspect of an embodiment of the present invention also provides a colorful composite coating for the outer shell of an EMU, which includes: a connecting layer with special decorative and functional effects connecting the primer layer and the varnish layer, or connecting the topcoat layer and the varnish layer; wherein the connecting layer is formed by the aforementioned connecting layer composition for colorful paint.

[0062] In some preferred embodiments, the primer layer includes a waterborne polyurethane intermediate paint, a waterborne epoxy intermediate paint, a waterborne polyurethane basecoat layer, or a waterborne polyurethane topcoat layer.

[0063] In some preferred embodiments, the clearcoat layer comprises a waterborne polyurethane clearcoat layer or a modified waterborne polyurethane clearcoat layer.

[0064] For example, the composite coating includes water-based epoxy primer, putty, water-based PU mid-coat, water-based PU base paint / water-based PU topcoat, water-based PU decorative connecting coating / water-based PU colorful paint, and water-based PU varnish; the composite coating structure also includes the aforementioned connecting layer.

[0065] The present invention is further illustrated below with reference to the accompanying drawings and several examples, but the invention is not limited to the scope of these examples. The reagents and raw materials used in the following examples are all commercially available. For example, the EPE-2000 block polyether is produced by Jiangsu Hongtaiyang New Polyether, and the EPE-3000 block polyether is produced by Zhejiang Dahua Resin Chemical; maleic anhydride is produced by Zibo Qixiang Tengda Chemical, and dicumyl peroxide (DCP) initiator is produced by Nouryon. Experimental methods where specific conditions are not specified are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers. In the following examples, low-speed stirring refers to a linear speed of 10 m / s or less, high-speed stirring refers to a linear speed of 20 m / s or more, and 10-20 m / s refers to a medium-speed stirring.

[0066] Example 1 A connecting layer composition for colorful paint and its preparation method and application, comprising the following steps:

[0067] (1) a. Dissolve 100 g of EPE-2000 block polyether in 0.5 g of NMP solvent to form a uniform solution at a temperature between 25 and 30°C; b. Keep the temperature constant and gradually add 0.2 g of DCP initiator to the EPE-2000 solution under stirring; c. Gradually add 3.2 g of maleic anhydride to the solution at a temperature between 30°C and 40°C to ensure that it is fully mixed with EPE-2000; d. Carry out the grafting reaction at a controlled temperature between 160°C and 180°C and a stirring speed of 320-380 rpm, and keep the temperature constant for 8 hours; e. After the reaction is cooled, remove the unreacted raw materials and by-products by filtering, washing, drying, etc. to obtain MAH-modified EPE type block polyether resin.

[0068] (2) Under the condition of room temperature to slightly above room temperature (e.g., 20° C. to 45° C.), 70 g of Wanhua Wantipro 0678 (hydroxyl content based on solid content is 1.2%, non-volatile matter is 24%), 20 g of MAH-modified EPE type block polyether resin obtained in step (1), and 10 g of water-based fumed silica M-5 (CABOT, USA) are added into a stirred kettle, and the mixture is evenly mixed, and then dispersed at a rotation speed of 1000-1500 r / min for 20-25 min to obtain a modified high surface tension hydroxypropylene resin for use.

[0069] (3) Under low-speed stirring conditions, 330 g of Matsuo A12G resin (hydroxyl content based on solids is 1.2%, non-volatile matter is 45%) and 330 g of Matsuo A20G resin (hydroxyl content based on solids is 2.0%, non-volatile matter is 45%) were added in sequence; 100 g of the modified high surface tension hydroxypropyl resin prepared in step (2) was added, and a small amount of DMEA was used to adjust the pH value to 8.0-8.5, and the mixture was stirred evenly; under medium-speed stirring, 30 g of BYK8421 directional additive was added, and the mixture was dispersed at high speed for 25 min-30 min, during which 50 g of cosolvent BCS and PM were added. 30g, and 15g of defoaming agent, leveling agent and wetting agent in total, adjust to medium speed, add 10g of Guansheng CXI-LH100 laser powder, 10g of deionized water, and DMEA, adjust the pH value to 7.8-8.3, and 0-5g of Hemmings 299 polyurethane associative thickener to adjust the viscosity to 75-85KU / 25°; after stirring evenly, the first component is obtained.

[0070] (4) Under the protection of nitrogen, 250g of anhydrous PMA propylene glycol methyl ether acetate was put into the container, and 750g of Wanhua water-based curing agent was slowly added under stirring. 268 (NCO (isocyanate group) content is between 20-21%), and continue stirring at low speed for 15-20 minutes until uniform, to obtain the second component.

[0071] (5) The first component, the second component, and the third component, preferably water, are mixed uniformly in a mass ratio of 10:1.2:2-3 to obtain a connecting layer composition of the colorful paint.

[0072] (6) The composite coating used in the test is: base coat + colorful paint + clear coat; base coat (XH0129AL-790M-SF waterborne polyurethane metallic paint from Xinhe New Materials); colorful paint (the connecting layer composition obtained in step (5)); clear coat (XH0118-000090-SF waterborne polyurethane clear coat from Xinhe New Materials); specific process: under high temperature and high humidity (temperature 30-40°C, humidity 80-90%); spray base coat with a dry film thickness of 20±5μm, level for 20-30min, spray colorful paint with a dry film thickness of 5±3μm; then spray water-based clear coat wet-on-wet with a dry film thickness of 60±10μm to obtain a composite coating. The surface effect of the composite coating in Example 1 is shown in the figure below. Figure 2 The test results are shown in Table 1.

[0073] Example 2 A connecting layer composition for colorful paint and its preparation method and application, comprising the following steps:

[0074] (1) a. Dissolve 100 g of EPE-2000 block polyether in 0.5 g of NMP solvent to form a uniform solution at a temperature between 25 and 30°C; b. Keep the temperature constant and gradually add 0.2 g of DCP initiator to the EPE-2000 solution under stirring; c. Gradually add 2.5 g of maleic anhydride to the solution at a temperature between 30°C and 40°C to ensure that it is fully mixed with EPE-2000; d. Carry out the grafting reaction at a controlled temperature between 160°C and 180°C and a stirring speed of 320-380 rpm, and keep the temperature constant for 8 hours; e. After the reaction is cooled, remove the unreacted raw materials and by-products by filtering, washing, drying, etc. to obtain MAH-modified EPE type block polyether resin.

[0075] (2) Under the condition of room temperature to slightly above room temperature (e.g., 20° C. to 45° C.), 75 g of Wanhua Wantipro 0678 (hydroxyl content based on solid content is 1.2%, non-volatile matter is 24%), 15 g of MAH-modified EPE type block polyether resin obtained in step (1), and 10 g of water-based fumed silica M-5 (CABOT, USA) are added into a stirred tank, and the mixture is evenly mixed, and then dispersed at a rotation speed of 1000-1500 r / min for 20-25 min to obtain a modified high surface tension hydroxypropylene resin for use.

[0076] (3) Under low-speed stirring conditions, 300 g of Matsuo A12G resin (hydroxyl content based on solids is 1.2%, non-volatile matter is 45%) and 300 g of Matsuo A20G resin (hydroxyl content based on solids is 2.0%, non-volatile matter is 45%) were added in sequence; 160 g of the modified high surface tension hydroxypropyl resin prepared in step (2) was added, and a small amount of DMEA was used to adjust the pH value to 8.0-8.5, and the mixture was stirred evenly; under medium-speed stirring, 30 g of BYK8421 directional additive was added, and the mixture was dispersed at high speed for 25 min-30 min, during which 50 g of cosolvent BCS and PM were added. 30g, and 15g of defoaming agent, leveling agent and wetting agent in total, adjust to medium speed, add 10g of Guansheng CXI-LH100 laser powder, 10g of deionized water, and DMEA, adjust the pH value to 7.8-8.3, and 0-5g of Hemmings 299 polyurethane associative thickener to adjust the viscosity to 75-85KU / 25°; after stirring evenly, the first component is obtained.

[0077] (4) Under the protection of nitrogen, 140g of anhydrous PMA propylene glycol methyl ether acetate was put into the container, and 860g of Wanhua water-based curing agent was slowly added under stirring. 268 (NCO (isocyanate group) content is between 20-21%), and continue stirring at low speed for 15-20 minutes until uniform, to obtain the second component.

[0078] (5) The first component, the second component, and the third component, preferably water, are mixed uniformly in a mass ratio of 10:1:2-3 to obtain a connecting layer composition of the colorful paint.

[0079] (6) The composite coating used in the test is: basecoat + color paint + clearcoat; basecoat (XH0129AL-790M-SF waterborne polyurethane metallic paint from Xinhe New Materials); color paint (the connecting layer composition obtained in step (5)); clearcoat (XH0118-000090-SF waterborne polyurethane clearcoat from Xinhe New Materials); specific process: under high temperature and high humidity conditions (temperature 30-40°C, humidity 80-90%); spray basecoat to a dry film thickness of 20±5μm, level for 20-30 minutes, then spray color paint to a dry film thickness of 5±3μm; then spray waterborne clearcoat wet-on-wet to a dry film thickness of 60±10μm; and obtain a composite coating. The test results are shown in Table 1.

[0080] Example 3 A connecting layer composition for colorful paint and its preparation method and application, comprising the following steps:

[0081] (1) a. Dissolve 100 g of EPE-3000 block polyether in 1 g of NMP solvent to form a uniform solution at a temperature between 25°C and 30°C; b. Keep the temperature constant and gradually add 0.2 g of DCP initiator to the EPE-3000 solution under stirring; c. Gradually add 2.8 g of maleic anhydride to the solution at a temperature between 30°C and 40°C to ensure that it is fully mixed with EPE-3000; d. Carry out the grafting reaction at a controlled temperature between 160°C and 180°C and a stirring speed of 320-380 rpm, and keep the temperature constant for 8 hours; e. After the reaction is cooled, remove the unreacted raw materials and by-products by filtering, washing, drying, etc. to obtain MAH-modified EPE type block polyether resin.

[0082] (2) At room temperature or slightly above room temperature (e.g., 20° C. to 45° C.), 80 g of Wanhua Wantipro 0678 (1.2% hydroxyl content based on solids, 24% non-volatile matter) containing carboxyl functional groups, 15 g of the MAH-modified EPE type block polyether resin obtained in step (1), and 5 g of water-based fumed silica AEROSIL 380 (Evonik) are added to a stirred tank, and the mixture is uniformly mixed, and then dispersed at a rotation speed of 1000-1500 r / min for 20-25 min to obtain a modified high surface tension hydroxypropylene resin for use.

[0083] (3) Under low-speed stirring conditions, 310 g of Matsuo A12G resin (hydroxyl content based on solids is 1.2%, non-volatile matter is 45%) and 310 g of Matsuo A20G resin (hydroxyl content based on solids is 2.0%, non-volatile matter is 45%) were added in sequence; 140 g of the modified high surface tension hydroxypropyl resin prepared in step (2) was added, and a small amount of DMEA was used to adjust the pH value to 8.0-8.5, and the mixture was stirred evenly; under medium-speed stirring, 30 g of BYK8421 directional additive was added, and the mixture was dispersed at high speed for 25 min-30 min, during which 50 g of cosolvent BCS and PM were added. 30g, and 15g of defoaming agent, leveling agent and wetting agent in total, adjust to medium speed, add 10g of Guansheng CXI-LH100 laser powder, 10g of deionized water, and DMEA, adjust the pH value to 7.8-8.3, and 0-5g of Hemmings 299 polyurethane associative thickener to adjust the viscosity to 75-85KU / 25°; after stirring evenly, the first component is obtained.

[0084] (4) Under nitrogen protection, 300 g of anhydrous PGDA propylene glycol diacetate was added to a container, and 700 g of Wanhua water-based curing agent Aquolin 270 (NCO (isocyanate group) content between 21-22%) was slowly added under stirring. The mixture was stirred at a low speed for 15-20 min until uniform, thereby obtaining the second component.

[0085] (5) The first component, the second component, and the third component, preferably water, are mixed uniformly in a mass ratio of 10:1.2:2-3 to obtain a connecting layer composition of the colorful paint.

[0086] (6) The composite coating used in the test is: basecoat + color paint + clearcoat; basecoat (XH0129AL-790M-SF waterborne polyurethane metallic paint from Xinhe New Materials); color paint (the connecting layer composition obtained in step (5)); clearcoat (XH0118-000090-SF waterborne polyurethane clearcoat from Xinhe New Materials); specific process: under high temperature and high humidity conditions (temperature 30-40°C, humidity 80-90%); spray basecoat to a dry film thickness of 20±5μm, level for 20-30 minutes, then spray color paint to a dry film thickness of 5±3μm; then spray waterborne clearcoat wet-on-wet to a dry film thickness of 60±10μm; and obtain a composite coating. The test results are shown in Table 1.

[0087] Example 4 A connecting layer composition for colorful paint and its preparation method and application, comprising the following steps:

[0088] (1) a. Dissolve 100 g of EPE-3000 block polyether in 1 g of NMP solvent to form a uniform solution at a temperature between 25 and 30°C; b. Keep the temperature constant and gradually add 0.2 g of DCP initiator to the EPE-3000 solution under stirring; c. Gradually add 2.5 g of maleic anhydride to the solution at a temperature between 30°C and 40°C to ensure that it is fully mixed with EPE-3000; d. Carry out the grafting reaction at a controlled temperature between 160°C and 180°C and a stirring speed of 320-380 rpm, and keep the temperature constant for 8 hours; e. After the reaction is cooled, remove the unreacted raw materials and by-products by filtering, washing, drying, etc. to obtain MAH-modified EPE type block polyether resin.

[0089] (2) Under the condition of room temperature to slightly above room temperature (e.g., 20° C. to 45° C.), 72 g of Wanhua Wantipro 0678 (hydroxyl content based on solid content is 1.2%, non-volatile matter is 24%), 10 g of MAH-modified EPE type block polyether resin obtained in step (1), and 8 g of water-based fumed silica AEROSIL 380 (Evonik) are added into a stirred kettle, and the mixture is evenly mixed, and then dispersed at a rotation speed of 1000-1500 r / min for 20-25 min to obtain a modified high surface tension hydroxypropylene resin for use.

[0090] (3) Under low-speed stirring conditions, add 280g of Matsuo A12G resin (hydroxyl content based on solid content is 1.2%, non-volatile matter is 45%) and 280g of Matsuo A20G resin (hydroxyl content based on solid content is 2.0%, non-volatile matter is 45%) in sequence; add 200g of the modified high surface tension hydroxypropyl resin prepared in step (2), and adjust the pH value to 8.0-8.5 with a small amount of DMEA, and stir evenly; under medium-speed stirring, add 30g of BYK8421 directional additive, and disperse at high speed for 25min-30min, during which time add 50g of cosolvent BCS, PM 30g, and 15g of defoaming agent, leveling agent and wetting agent in total, adjust to medium speed, add 10g of Guansheng CXI-LH100 laser powder, 10g of deionized water, and DMEA, adjust the pH value to 7.8-8.3, and 0-5g of Hemmings 299 polyurethane associative thickener to adjust the viscosity to 75-85KU / 25°; after stirring evenly, the first component is obtained.

[0091] (4) Under nitrogen protection, 200 g of anhydrous PGDA propylene glycol diacetate was added to a container, and 700 g of Wanhua water-based curing agent Aquolin 269A (NCO (isocyanate group) content between 18.8% and 19.8%) was slowly added under stirring. The mixture was stirred at a low speed for 15-20 minutes until uniform, thereby obtaining the second component.

[0092] (5) The first component, the second component, and the third component, preferably water, are mixed uniformly in a mass ratio of 10:1.1:2-3 to obtain a connecting layer composition of the colorful paint.

[0093] (6) The composite coating used in the test is: basecoat + color paint + clearcoat; basecoat (XH0129AL-790M-SF waterborne polyurethane metallic paint from Xinhe New Materials); color paint (the connecting layer composition obtained in step (5)); clearcoat (XH0118-000090-SF waterborne polyurethane clearcoat from Xinhe New Materials); specific process: under high temperature and high humidity conditions (temperature 30-40°C, humidity 80-90%); spray basecoat to a dry film thickness of 20±5μm, level for 20-30 minutes, then spray color paint to a dry film thickness of 5±3μm; then spray waterborne clearcoat wet-on-wet to a dry film thickness of 60±10μm; and obtain a composite coating. The test results are shown in Table 1.

[0094] Comparative Example 1

[0095] The present comparative example provides a connecting layer composition for a colorful paint and its preparation method which are substantially the same as those in Example 1, except that steps (1) and (2) are omitted, and in step (3), 380g of Matsuo A12G resin and 380g of Matsuo A20G resin are used without adding a modified high surface tension hydroxypropyl resin. In step (5), the corresponding ratio is 10:1.3:2-3 for the first component and the second component, and the third component is preferably water; the surface effect diagram of the composite coating in Example 1 is shown in FIG. Figure 1 The test results are shown in Table 1.

[0096] Comparative Example 2

[0097] The connecting layer composition for colorful paint and the preparation method thereof provided in this comparative example are basically the same as those in Example 1, except that the carboxyl functional group-containing hydroxyl acrylic emulsion Wanhua Wantipro 0678 is omitted in step (2) and replaced entirely with MAH-modified EPE-type block polyether resin;

[0098] Within one week at room temperature (25±3°C), phase separation, stratification, or precipitation may occur, affecting the stability and performance of the coating. The test results are shown in Table 1.

[0099] Comparative Example 3

[0100] The connecting layer composition for a colorful paint and the preparation method thereof provided in this comparative example are substantially the same as those in Example 1, except that the carboxyl functional group-containing hydroxyl acrylic emulsion Wanhua Wantipro 0678 is omitted in step (2) and is replaced by the carboxyl functional group-free hydroxyl acrylic emulsion Matsuo A12G resin.

[0101] Within one week at room temperature (25±3°C), phase separation, stratification, or precipitation may occur, affecting the stability and performance of the coating. The test results are shown in Table 1.

[0102] Comparative Example 4

[0103] The connecting layer composition for colorful paint and its preparation method provided in this comparative example are basically the same as those in Example 1, with the only difference being that the hydrophilic fumed silica is omitted in step (2); (the water-based fumed silica can accelerate the migration of high surface tension resins during rapid construction (wet spraying), while slightly accelerating the surface drying time of the wet film). The test results are shown in Table 1.

[0104] Comparative Example 5

[0105] The connecting layer composition for colorful paint and its preparation method provided in this comparative example are basically the same as those in Example 1, with the only difference being that: the directional additive (BYK8421) is omitted in step (3); in step (3), the content of the rheological additive is increased and adjusted to the same viscosity of 75-85KU / 25°C.

[0106] The problems with this comparative example include: uneven color and uneven coating; the metallic texture may be weakened or even disappear, making the coating look more bland; and the arrangement is disorderly, which may reduce the glossiness. The test results are shown in Table 1.

[0107] Comparative Example 6

[0108] The connecting layer composition for a colorful paint and the preparation method thereof provided in this comparative example are substantially the same as those in Example 1, except that the composite coating lacks the connecting layer in Example 1, steps (1) to (5) are omitted, and the colorful powder is directly added to the clear coat in step (6);

[0109] This comparative example suffers from the following problems: a. Direct addition results in poor orientation, resulting in a loss of decorative effect, and a hard precipitate forms after one month of storage. b. Adding an orientation aid directly results in matte finish, reducing gloss and overall fullness. Furthermore, the alignment effect is poor, resulting in a loss of high decorative effect. See Table 1 for test results.

[0110] Comparative Example 7

[0111] The connecting layer composition for colorful paint and its preparation method provided in this comparative example are basically the same as those in Example 1, except that steps (1) and (2) are omitted, and 760g of the medium hydroxy resin Wanhua is used in step (3). 2035 (3.0% hydroxyl content based on solids, 43% non-volatile matter); without adding modified high surface tension hydroxypropyl resin.

[0112] In step (5), the corresponding ratio is: the mass ratio of the first component, the second component and the third component (water) is 10:2.3:2-3;

[0113] The problems existing in this comparative example are: the surface drying speed is too slow, the orientation is too poor, and the solvent of the varnish dissolves the surface layer of the bottom layer, causing the surface layer to wrinkle. The test results are shown in Table 1.

[0114] Comparative Example 8

[0115] The connecting layer composition for colorful paint and its preparation method provided in this comparative example are basically the same as those in Application Example 1, except that steps (1) and (2) are omitted, and 760g of the medium hydroxy resin Wanhua is used in step (3). 2042 (3.0% hydroxyl content based on solids, 43% non-volatile matter); without adding modified high surface tension hydroxypropyl resin.

[0116] In step (5), the corresponding ratio is: the first component, the second component and the third component (water) according to the mass ratio of 10:3.4:2-3;

[0117] Problems existing in this comparative example: Same as comparative example 7, test results are shown in Table 1.

[0118] Table 1

[0119]

[0120]

[0121] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0122] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical variations made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the scope of protection of the present invention.

Claims

1. A connecting layer composition for colorful paint, characterized in that: The invention comprises a first component and a second component; the first component comprises a water-based hydroxypropylene resin, a modified high surface tension hydroxypropylene resin, a directional additive, a first cosolvent, an additive, a dazzling powder, water, and a rheological additive which may or may not be used; the second component comprises a water-based curing agent and a second cosolvent; The preparation method of the modified high surface tension hydroxypropylene resin comprises: A mixed reaction system comprising an EPE-type block polyether, maleic anhydride, dicumyl peroxide, and a solvent is subjected to a grafting reaction at 160-180° C. for 3-5 hours, followed by post-treatment to obtain an MAH-modified EPE-type block polyether resin. Furthermore, the MAH-modified EPE type block polyether resin is mixed with a hydroxy acrylic emulsion containing a carboxyl functional group and hydrophilic fumed silica to prepare a modified high surface tension hydroxy acrylic resin.

2. The tie layer composition according to claim 1, characterized in that The first component includes the following components calculated in parts by weight: 65-75 parts of water-based hydroxypropylene resin, 10-20 parts of modified high surface tension hydroxypropylene resin, 2-5 parts of directional additive, 4-8 parts of first cosolvent, 2-3 parts of additive, 0.3-5 parts of colorful powder, 8-14 parts of water and 0-0.5 parts of rheological additive.

3. The tie layer composition according to claim 1, characterized in that The second component includes the following components calculated in parts by weight: 70-90 parts of a water-based curing agent and 10-30 parts of a second co-solvent.

4. The tie layer composition according to claim 1, characterized in that The mass ratio of the first component to the second component is 10:1~1.

5.

5. The tie layer composition according to claim 1, characterized in that The connecting layer composition further includes a third component; the third component includes water; and the mass ratio of the first component, the second component and the third component is 10:1-1.5:2-4.

6. The tie layer composition according to claim 1, wherein: The EPE type block polyether is an EPE type block polyether with a high ethylene oxide structure content, and the molar ratio of ethylene oxide to propylene oxide structures in the EPE type block polyether is greater than 1.

5.

7. The tie layer composition according to claim 1, wherein: The weight average molecular weight of the EPE type block polyether is 2000-3000.

8. The tie layer composition according to claim 1, wherein: The solvent includes N-methylpyrrolidone and / or dimethyl sulfoxide.

9. The tie layer composition according to claim 1, wherein: The carboxyl functional group-containing hydroxyl acrylic emulsion is a core-shell polyacrylate emulsion; the hydroxyl content in the core-shell polyacrylate emulsion is 1.0-1.4% based on solid content.

10. The tie layer composition according to claim 1, wherein: The mass ratio of the EPE type block polyether, maleic anhydride, dicumyl peroxide and solvent is 100:2.5-3.2:0.2-0.3:0-2.

11. The tie layer composition according to claim 1, wherein: The mass ratio of the carboxyl functional group-containing hydroxy acrylic emulsion, the MAH-modified EPE type block polyether resin and the hydrophilic fumed silica is 70-80:10-20:5-10.

12. The tie layer composition according to claim 1, wherein: The hydroxyl value content of the water-based hydroxypropylene resin is 1.2-3.2 wt %.

13. The tie layer composition according to claim 1, wherein: The weight average molecular weight of the modified high surface tension hydroxypropylene resin is 100,000-200,000.

14. The tie layer composition according to claim 1, wherein: The modified high surface tension hydroxypropylene resin has a hydroxyl value content of 1.0-1.4 wt %.

15. The tie layer composition according to claim 1, wherein: The directional auxiliary agent includes non-ionic modified ethylene-vinyl acetate copolymer wax emulsion and / or polyamide wax.

16. The tie layer composition according to claim 1, wherein: The first cosolvent includes any one or more combinations of propylene glycol methyl ether, n-butanol, dipropylene glycol butyl ether, isopropyl alcohol, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol butyl ether, and dipropylene glycol methyl ether.

17. The tie layer composition according to claim 1, wherein: The auxiliary agent includes any one or more combinations of defoaming agents, leveling agents, and wetting agents.

18. The tie layer composition according to claim 1, wherein: The colorful powder includes any one or more combinations of laser powder, pearl powder, and chameleon pigment.

19. The tie layer composition according to claim 1, wherein: The water-based curing agent includes a water-dispersible isocyanate curing agent; the water-dispersible isocyanate curing agent includes any one or more combinations of Wanhua water-based curing agent Aquolin® 268, Wanhua water-based curing agent Aquolin 269A, and Wanhua water-based curing agent Aquolin 270; the NCO content of the water-dispersible isocyanate curing agent is 19-23wt%; the solid content of the water-dispersible isocyanate curing agent is 98-100wt%; and the viscosity of the water-dispersible isocyanate curing agent at 25°C is 500-6500mPa·s.

20. The tie layer composition according to claim 1, wherein: The second co-solvent includes propylene glycol methyl ether acetate and / or propylene glycol diacetate.

21. The method for preparing the connecting layer composition for colorful paint according to any one of claims 1 to 20, characterized in that: include: Evenly mixing a water-based hydroxypropyl resin, a modified high surface tension hydroxypropyl resin, a directional additive, a first cosolvent, an additive, a dazzling powder, water, and a rheological additive used or not to obtain a first component; Furthermore, the aqueous curing agent and the second cosolvent are evenly mixed to obtain a second component, thereby obtaining a connecting layer composition for colorful paint.

22. Use of the tie layer composition for colorful paint according to any one of claims 1 to 20 in the field of rail transit coating decoration.

23. A colorful composite coating for the outer shell of an EMU, characterized in that: include: A connecting layer with decorative and functional functions connecting a primer layer and a clear coat layer or connecting a top coat layer and a clear coat layer; wherein the connecting layer is formed by the connecting layer composition for colorful paint according to any one of claims 1-20.

24. The colorful composite coating according to claim 23, characterized in that: The primer layer includes a waterborne polyurethane intermediate paint, a waterborne epoxy intermediate paint, a waterborne polyurethane base paint layer or a waterborne polyurethane top paint layer.

25. The colorful composite coating according to claim 23, characterized in that: The varnish layer comprises a water-based polyurethane varnish coating or a modified water-based polyurethane varnish coating.

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