Anti-sagging water-based midcoat for automobiles, and preparation method and use thereof

Abstract

The application discloses an anti-sagging water-based intermediate coating for automobiles, which comprises the following components in parts by weight: amino resin 5-12 parts; acrylic resin 5-10 parts; polyester resin 5-10 parts; polyurethane resin 1-10 parts; modified polyol 1-3 parts; thickening agent 0.01-2.2 parts; wetting agent 0.1-0.8 parts; high-molecular dispersant 0.5-1.5 parts; PH regulator 0.1-1 part; defoaming agent 0.1-0.5 parts; pigment 1-20 parts; filler 10-30 parts; solvent 2-9 parts; and deionized water 10-30 parts. The water-based intermediate coating can solve the problem that the 'wet-on-wet' process of the water-based intermediate coating for automobiles has a great influence on the construction and film performance of the product, and often leads to sagging, color floating and other problems. The application further discloses a preparation method and application of the water-based intermediate coating.

Description

Technical Field

[0001] This invention relates to the field of coatings. More specifically, it relates to an anti-sagging intermediate coating for automobiles, its preparation method, and its uses. Background Technology

[0002] With increasing awareness of environmental protection and energy conservation, water-based coatings have become a common trend in the automotive industry. Among these, the "wet-on-wet" 3-coat 1B1PH process, due to its energy-saving and cost-reducing advantages, is gradually becoming a popular direction in water-based coatings and is being used more and more widely. However, because the completely "wet-on-wet" process has a significant impact on product application and paint film performance, it often leads to problems such as sagging and color floating. Summary of the Invention

[0003] Based on the above shortcomings, the purpose of this invention is to provide an anti-sagging water-based intermediate coating for automobiles, its preparation method and application, so as to at least solve the problem that the "wet-on-wet" process of automotive water-based intermediate coatings has a great impact on the application and film performance of the product, often leading to problems such as sagging and floating color.

[0004] On one hand, the present invention provides an anti-drip water-repellent intermediate coating for automobiles, comprising the following components in parts by weight:

[0005] 5-12 parts of amino resin;

[0006] 5-10 parts acrylic resin;

[0007] 5-10 parts of polyester resin;

[0008] 1-10 parts of polyurethane resin;

[0009] 1-3 parts of modified polyol;

[0010] Thickener 0.01-2.2 parts;

[0011] Wetting agent 0.1-0.8 parts;

[0012] 0.5-1.5 parts of polymeric dispersant;

[0013] pH adjuster 0.1-1 part;

[0014] 0.1-0.5 parts of defoamer;

[0015] 1-20 parts pigment;

[0016] 10-30 parts of filler;

[0017] Solvent 2-9 parts;

[0018] 10-30 parts deionized water.

[0019] Furthermore, the thickener comprises:

[0020] Inorganic thickener 0.01-0.2 parts;

[0021] 0-1 part of associative thickener;

[0022] 0-1 part of alkali-swellable thickener.

[0023] Furthermore, the associative thickener is an associative polyurethane thickener; and / or

[0024] The alkali-swelling thickener is a non-associative polyacrylate alkali-swelling emulsion.

[0025] Furthermore, the solvent contains 1-5 parts of high-boiling-point olefin solvent and 1-4 parts of alcohol ether solvent.

[0026] Furthermore, the intermediate coating also contains 0.01-0.8 parts of surface tension modifier.

[0027] Furthermore, the intermediate coating also contains 0-3 parts of colorant; and / or

[0028] The solvent also contains 0-4 parts of anti-settling agent.

[0029] Furthermore, the amino resin is a methylated amino resin.

[0030] Furthermore, the modified polyol is selected from one or more of polyether polyols and polyester polyols.

[0031] Secondly, the present invention provides a method for preparing the above-mentioned anti-drip water-resistant intermediate coating for automobiles, comprising the following steps:

[0032] Under stirring conditions of 500-800 r / min, a portion of deionized water, a portion of pH adjuster, dispersant, a portion of defoamer, pigment, filler, and inorganic thickener are added sequentially to the reaction vessel and stirred for 15-20 minutes. The mixture is then ground to a fineness of ≤15μm using a sand mill to prepare a grinding slurry.

[0033] While stirring the grinding slurry at a speed of 400-500 rpm, sequentially add acrylic resin, polyester resin, polyurethane resin, amino resin, a portion of pH adjuster, polyamide wax, grinding slurry, a portion of defoamer powder, solvent, leveling agent, surface tension adjuster, and thickener to adjust to the appropriate viscosity and pH value. Use color paste to adjust to the appropriate color. Dilute to the specified viscosity with a thinner before use.

[0034] Thirdly, the present invention provides the use of the anti-drip water intermediate coating for automobiles as described above as an automotive paint.

[0035] Furthermore, the application includes the following steps: using the water-based intermediate coating in a wet-on-wet process.

[0036] The beneficial effects of this invention are as follows:

[0037] The water-based intermediate coating provided in this invention, by combining different types and amounts of resin, improves the interfacial effect of the coating, reduces the wetting effect of the color paint on the intermediate coating, and prevents problems such as floating color, blooming, and sagging. Further optimization by combining different types of thickeners further improves the thickening effect, anti-dilution properties, and leveling properties of the intermediate coating, increasing the fullness of the coating. By using a substrate wetting agent to adjust the surface tension of the sample paint, and combining it with a surface tension adjuster, the wettability of the intermediate coating is improved while reducing the penetration of the color paint into the intermediate coating, thus preventing problems such as floating color, blooming, and sagging. When the surface tension of the intermediate coating is low, it can reduce the wetting of the color paint into the intermediate coating, thereby reducing the blooming of the color paint, but it is prone to interlayer sagging. When the surface tension is high, the color paint is more likely to penetrate into the intermediate coating, making it most prone to blooming. Therefore, by adjusting the appropriate surface tension, a suitable spraying effect is achieved. At the same time, using a surface tension adjuster to increase the surface tension of the dry film helps improve the leveling and wetting effect of the clear coat and repair paint. Attached Figure Description

[0038] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0039] Figure 1 The appearance of the wet film obtained in Example 1 is shown.

[0040] Figure 2 The appearance of the wet film obtained in Comparative Example 1 is shown. Detailed Implementation

[0041] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0042] A specific embodiment of the present invention provides an anti-drip water intermediate coating for automobiles, comprising the following components in parts by weight:

[0043] 5-12 parts of amino resin;

[0044] 5-10 parts acrylic resin;

[0045] 5-10 parts of polyester resin;

[0046] 1-10 parts of polyurethane resin;

[0047] 1-3 parts of modified polyol;

[0048] Thickener 0.01-2.2 parts;

[0049] Wetting agent 0.1-0.8 parts;

[0050] 0.5-1.5 parts of polymeric dispersant;

[0051] pH adjuster 0.1-1 part;

[0052] 0.1-0.5 parts of defoamer;

[0053] 1-20 parts pigment;

[0054] 10-30 parts of filler;

[0055] Solvent 2-9 parts;

[0056] 10-30 parts deionized water.

[0057] In the above technical solutions, the acrylic resin can exist in the form of a resin or in the form of an emulsion. For example, the acrylic resin can be a water-soluble propylene resin, an aqueous propylene emulsion, or a modified acrylic emulsion. Exemplary acrylic resins include, but are not limited to, those from BASF. PU 1035W, Luhydran S 938T, and one or more of Guangshu Company's water-based acrylic resin GS-360, etc. The reaction of acrylic resin / emulsion with amino resin gives the paint film better appearance and performance.

[0058] In some preferred embodiments, the amino resin is a methyl etherified amino resin, including but not limited to one or both of CYMEL327 and CYMEL370 from Zhanxin Company. The amino resin reacts with other resins to give the paint film a good appearance and crosslinking density.

[0059] In the above technical solution, the polyester resin can exist in the form of a resin or an emulsion. For example, the polyester resin can be a water-based polyester resin or a water-based polyester emulsion. Exemplary polyester resins include, but are not limited to, one or more of HOMPAPE-4200-80 from Jintuan Company and BCNW 3324 from Tongde Company. The polyester resin provides the paint film with good flexibility and appearance.

[0060] In the above technical solutions, the polyurethane resin can exist in the form of a resin or in the form of an emulsion. Exemplary polyurethane resins include, but are not limited to: waterborne polyurethane resins, waterborne polyurethane emulsions, and polyester resins such as DSM's NeoPacE-122 and Lubrizol's AptalonTMM8100. Polyurethane resins provide the coating film with good flexibility and appearance.

[0061] In this technical solution, by combining different types and amounts of resins, the interface effect of the coating is improved, the wetting effect of the paint on the intermediate coat is reduced, and problems such as floating color, blooming, and sagging are prevented. On this basis, further optimization and combination of different types of thickeners can better improve the thickening effect, anti-dilution properties, and leveling properties of the intermediate coat, and increase the fullness of the coating.

[0062] In some examples, the thickener contains:

[0063] Inorganic thickener 0.01-0.2 parts;

[0064] 0-1 part of associative thickener;

[0065] 0-1 part of alkali-swellable thickener.

[0066] Preferably, the inorganic thickener is one or two of lithium magnesium silicate (e.g., BYK's Laponite RD) and montmorillonite clay rheology modifiers (e.g., Hemings' BENTONE LT). The aforementioned inorganic thickeners are all high-performance thickeners that provide thermal stability of viscosity and good thixotropy.

[0067] Preferably, the associative thickener is an associative polyurethane thickener. For example, one or both of Rohm and Haas's 8W and 12W thickeners. Associative thickeners provide excellent viscosity thickening efficiency and superb leveling properties; in formulations of large-particle-size emulsions, they exhibit excellent high-shear viscosity thickening effects and superior leveling properties, improving coating fullness. The amount of associative thickener added includes, but is not limited to, 0.1-1 parts, 0.1-0.7 parts, etc.

[0068] Preferably, the alkali-swellable thickener is a non-associative polyacrylate alkali-swellable emulsion. For example, one or both of Rohm and Haas's ASE 60 and Ciba's Viscalex HV-30. Alkali-swellable thickeners have good thickening effects and, when combined with associative thickeners, achieve a morphological thickening effect on resins, particles, and water. The amount of alkali-swellable thickener added includes, but is not limited to, 0.1-1 parts, 0.1-0.7 parts, etc.

[0069] The above-mentioned different types of thickeners, and the combination of multiple thickeners, give the intermediate coating good thixotropic viscosity and resistance to dilution. Preferably, the thickener includes:

[0070] Inorganic thickener 0.01-0.2 parts; with

[0071] One or a mixture of two of the following: 0.1-1 parts of associative thickener or 0.1-1 parts of alkali-swellable thickener.

[0072] In some examples, the solvent contains 1-5 parts of a high-boiling-point olefin solvent and 1-4 parts of an alcohol ether solvent. The high-boiling-point olefin solvent includes, but is not limited to, one or more of BYK-WS and BYK-WA from BYK Corporation, and SHELLSOLTK from Shell. The high-boiling-point olefin solvent can be used to prevent surface defects such as pinholes, orange peel, blistering, and pores, and to prevent boiling marks, resulting in excellent leveling properties. The alcohol ether solvent includes, but is not limited to, one or more of dipropylene glycol dimethyl ether, dipropylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether, and ethylene glycol isooctyl ether. The alcohol ether solvent acts as a co-solvent, aiding in film formation.

[0073] In some examples, the intermediate coating also contains 0.01-0.8 parts of a surface tension modifier. Exemplary surface tension modifiers include, but are not limited to, BYK-3565 from BYK Corporation. Surface tension modifiers are surface additives that improve the surface energy of the dry film of the water-based system, while also providing anti-cratering properties.

[0074] In some examples, the intermediate coating also contains 0-3 parts of colorant; and / or

[0075] The solvent also contains 0-4 parts of anti-settling agent.

[0076] The colorant used is either homemade or commercially available, and is used for color mixing, including red, black, and yellow colorants. The amount of colorant used is small, primarily for color mixing.

[0077] In some examples, the modified polyol is selected from one or more of polyether polyols and polyester polyols. Specifically, it includes, but is not limited to, examples such as WANOL C2020 from Wanhua Chemical and 303LM from Dow Chemical. The modified polyol can help improve the appearance of the coating film.

[0078] In some examples, the polymeric dispersant is a commercially available product, such as those from Eucalyptus Corporation. One or both of the SPERSE series 688W and 685U. These polymeric dispersants exhibit excellent dispersion stability for both inorganic and organic pigments, as well as superior anti-floating and anti-blooming capabilities and viscosity-reducing abilities.

[0079] In some examples, the pH adjuster is methylethanolamine, a commercially available product, such as dimethylacetamide produced by Shandong Jiawei Chemical Co., Ltd.

[0080] In some examples, the defoamer is a commercially available product, such as one or more of the following: acetylenol defoamers (e.g., Evonik's Surfynol 104A), mineral oil defoamers (e.g., Senno Spectro's SN-Defoamer 1340, a paraffin-based defoamer), and silicone defoamers (e.g., BYK-024). The use of these defoamers can better help eliminate bubbles generated during film formation.

[0081] In some examples, the pigments are: titanium dioxide is commercially available rutile titanium dioxide, such as DuPont R-902, which has good dispersibility and whiteness; carbon black is a commercially available product, such as Orion high pigment channel carbon black FW200 (which has the advantages of high blackness, high gloss, and good dispersibility).

[0082] In some examples, the filler is: barium sulfate, a commercially available product (fineness ≤ 5μm), such as one or more of JLH-B7 and JLH-BF3 (Jinhaohui Company). This filler has good fineness, is easy to disperse, has good anti-settling stability, and is not prone to hard settling; talc, a commercially available product (fineness ≤ 5μm), such as JLH-60 talc (Jinhaohui Company), is used as a filler. It has good fineness, is easy to disperse, has good anti-settling stability, improves the anti-settling effect of the system, and provides flexibility to the paint film.

[0083] In some examples, the anti-settling agent is a polyamide wax, such as one or more of Hemings' THXATROL P2100W and Longhai Chemical's 7802. The anti-settling agent can provide anti-sagging and anti-settling effects in water-based coating systems.

[0084] In some examples, the wetting agent is an acetylenic diol product. For instance, Evonik's BETTERSOL 440, a acetylenic diol surfactant, is an ethylene oxide addition-modified acetylenic diol product. It possesses multifunctional properties of wetting, defoaming, and dispersing. BETTERSOL 440 exhibits excellent dynamic migration in the system, providing superior dynamic wetting, spreading, and leveling effects without affecting recoating; or silicone products, such as BYK-346 leveling agent, which is an additive combining anti-cratering and leveling properties. It can enhance coating gloss and improve long-wave leveling; slightly reduce surface tension without affecting recoatability and interlayer adhesion. This additive also has defoaming properties and good thermal stability.

[0085] Another embodiment of the present invention provides a method for preparing the above-mentioned anti-drip water-resistant intermediate coating for automobiles, the method comprising the following steps:

[0086] According to the raw material ratio, under stirring conditions at a speed of 500-800 r / min, a portion of deionized water, a portion of pH adjuster, dispersant, a portion of defoamer, pigment, filler, and inorganic thickener are added sequentially to the reaction vessel, stirred for 15-20 minutes, and ground to a fineness of ≤15μm using a sand mill to prepare a grinding slurry;

[0087] While stirring the grinding slurry at a speed of 400-500 rpm, sequentially add acrylic resin, polyester resin, polyurethane resin, amino resin, a portion of pH adjuster, polyamide wax, grinding slurry, a portion of defoamer powder, solvent, leveling agent, surface tension adjuster, and thickener to adjust to the appropriate viscosity and pH value. Use color paste to adjust to the appropriate color. Dilute to the specified viscosity with a thinner before use.

[0088] Another specific embodiment of the present invention provides the use of the anti-drip water intermediate coat for automobiles as described above as an automotive paint.

[0089] In some preferred examples,

[0090] The application includes the step of using the water-based intermediate coating in a wet-on-wet process.

[0091] The technical solution of the present invention will be described below with reference to some specific embodiments:

[0092] Examples 1-6 and Comparative Examples 1-5

[0093] The formulations of anti-drip intermediate coatings for automobiles are shown in Table 1 and Table 2, respectively.

[0094] The preparation of this water-based intermediate coating includes the following steps:

[0095] According to the raw material ratio, under stirring conditions at a speed of 500-800 r / min, a portion of deionized water, a portion of pH adjuster, dispersant, a portion of defoamer, pigment, filler, and inorganic thickener are added sequentially to the reaction vessel, stirred for 15-20 minutes, and ground to a fineness of ≤15μm using a sand mill to prepare a grinding slurry;

[0096] While stirring the grinding slurry at a speed of 400-500 rpm, sequentially add acrylic resin, polyester resin, polyurethane resin, amino resin, a portion of pH adjuster, polyamide wax, grinding slurry, a portion of defoamer powder, solvent, leveling agent, surface tension adjuster, and thickener to adjust to the appropriate viscosity and pH value. Use color paste to adjust to the appropriate color. Dilute to the specified viscosity with a thinner before use.

[0097] The preparation steps for each coating are as follows:

[0098] Wet-on-wet spraying process: Under the conditions of temperature 19-25℃ and humidity 70-90%, spray water-based intermediate coat (dry film thickness 20±5μm), level for 9 minutes, spray water-based color paint (dry film thickness 15±5μm), level for 2 minutes, then bake at 80℃ for 3 minutes, cool for about 3 minutes (to reduce the temperature to room temperature 19-25℃), spray clear coat (dry film thickness 40±5μm), level for 7 minutes, and bake at 140℃ for 30 minutes.

[0099] Table 1

[0100]

[0101]

[0102] Table 2

[0103]

[0104]

[0105] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An anti-sagging aqueous midcoat for automotive use, characterized by, The components include the following parts by weight: 5-12 parts of amino resin; 5-10 parts acrylic resin; 5-10 parts of polyester resin; 1-10 parts of polyurethane resin; 1-3 parts of modified polyol; Thickener 0.01-2.2 parts; Wetting agent 0.1-0.8 parts; 0.5-1.5 parts of polymeric dispersant; pH adjuster 0.1-1 part; 0.1-0.5 parts of defoamer; 1-20 parts pigment; 10-30 parts of filler; Solvent 2-9 parts; 10-30 parts deionized water; The thickener contains: 0.01-0.2 parts of inorganic thickener, 0.1-1 parts of associative thickener, and 0.1-1 parts of alkali-swellable thickener; The intermediate coating also contains 0.01-0.8 parts of surface tension modifier; The associative thickener is an associative polyurethane thickener; The alkali-swelling thickener is a non-associative polyacrylate alkali-swelling emulsion; The amino resin is a methylated amino resin; The modified polyol is selected from one or more of polyether polyols and polyester polyols; The polymeric dispersant is selected from one or two of the UNIQ® SPERSE series 688W and 685U from Uniqlo Corporation. The inorganic thickener is selected from one or two of lithium magnesium silicate and montmorillonite clay rheology modifiers. The surface tension modifier is BYK-3565 from BYK Corporation.

2. The anti-sagging aqueous basecoat for automobiles according to claim 1, characterized by, The solvent contains 1-5 parts of high-boiling-point olefin solvent and 1-4 parts of alcohol ether solvent; The high-boiling-point olefin solvent is selected from Shell's SHELLSOL TK.

3. The anti-sagging aqueous basecoat for automobiles according to claim 1, characterized by The intermediate coating also contains 0-3 parts of color paste.

4. The use of the anti-drip intermediate coating for automobiles as described in any one of claims 1-3 as an automotive paint.

5. Use according to claim 4, characterized in that, The water-based intermediate coating is used in the wet-on-wet process.

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