Water-based polyester resin composition, water-based primer surfacer containing water-based polyester resin composition, and preparation method and application of water-based primer surfacer

Abstract

The invention discloses a water-based polyester resin composition, a water-based intermediate coat containing the water-based polyester resin composition as well as a preparation method and application of the water-based intermediate coat. The water-based polyester resin composition comprises the following components: water-based polyester resin A with an acid value of 29 + / -2 mg KOH / g and a solid content of 68.7 + / -1.5 wt%; the acid value of the waterborne polyester resin B is 0-17 mg KOH / g or 70-80 mg KOH / g, and the solid content of the waterborne polyester resin B is 39-46 wt% or 95-100 wt%. After the water-based polyester resin composition is applied to water-based intermediate coat and is used for coating an automobile, the stone impact resistance of a paint film is effectively improved on the basis of not reducing the properties such as sagging property, pencil hardness, adhesive force, impact resistance, non-adhesion property and appearance of the paint film.

Description

Technical Field

[0001] The present invention relates to the technical field of waterborne coatings. More specifically, it relates to a waterborne polyester resin composition, a waterborne intermediate coating paint containing the waterborne polyester resin composition, and a preparation method and application thereof. Background Art

[0002] The intermediate coating mainly plays the role of enhancing the adhesion between coatings (intermediate coating and substrate, intermediate coating and topcoat), providing sealing and filling of fine traces to the substrate, and improving the appearance of the coating film. The intermediate coating primer must have strong adhesion, solvent resistance, and filling properties. In a coating system, since a single-layer coating cannot possess all the properties of the coating system, in order to make up for the defects of a single-layer coating, enhance the shielding performance, improve the appearance performance, prevent pinholes, and make the topcoat smoother and flatter, multiple-layer coatings are necessary. The intermediate coating plays a connecting role in the coating system, and it is required that the intermediate coating paint has good adhesion to the primer and the topcoat. The adhesion between the coating films is achieved by the solvent contained in the intermediate layer swelling the primer, making the polymer chains at the interface of the two layers entangle tightly and improving the compatibility. In order to form an overall protection system among the coatings, it is required that the intermediate coating paint has good adhesion to both the primer and the topcoat. The stone impact resistance of the existing waterborne intermediate coatings is at the lower limit of the standard. In order to better improve the stone impact resistance of the coatings and the overall performance of the composite coating, a new waterborne intermediate coating paint needs to be provided. Summary of the Invention

[0003] Based on the above problems, the purpose of the present invention is to provide a waterborne polyester resin composition, a waterborne intermediate coating paint containing the waterborne polyester resin composition, and a preparation method and application thereof, which can effectively improve the stone impact resistance on the basis of not reducing the properties such as sag resistance, pencil hardness, adhesion, impact resistance, non-stickiness, and appearance of the waterborne intermediate coating paint.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] On the one hand, the present invention provides a waterborne polyester resin composition, comprising the following components:

[0006] Waterborne polyester resin A, with an acid value of 29 ± 2 mg KOH / g and a solid content of 68.7 ± 1.5 wt%.

[0007] Waterborne polyester resin B, with an acid value of 0 - 17 mg KOH / g or 70 - 80 mg KOH / g and a solid content of 39 - 46 wt% or 95 - 100 wt%.

[0008] Further, in the molecular structure of the waterborne polyester resin A, it contains the following groups:

[0009] And terminal hydroxyl groups.

[0010] Further, the mass ratio of the aqueous polyester resin A to the aqueous polyester resin B is (3 - 5):(15 - 25).

[0011] On the other hand, the present invention provides an aqueous intermediate coat paint, comprising the following components in parts by weight:

[0012] 5 - 12 parts of an acrylic resin, 5 - 20 parts of an amino resin, 1 - 6 parts of a polyurethane resin, 18 - 30 parts of the aqueous polyester resin composition as described above, 20 - 35 parts of a pigment, 2 - 12 parts of an organic solvent, and 5 - 30 parts of deionized water.

[0013] Further, in the aqueous polyester resin composition, it contains 3 - 5 parts of the aqueous polyester resin A and 15 - 25 parts of the aqueous polyester resin B.

[0014] Further, it further contains additives, and the additives contain one or more of a dispersant, a rheology aid, an antifoaming agent, and a pH regulator.

[0015] Further, in the aqueous intermediate coat paint, it contains 0.5 - 3 parts of a dispersant, 0 - 2 parts of a rheology aid, 0 - 2 parts of an antifoaming agent, and 0 - 3 parts of a pH regulator.

[0016] On the other hand, the present invention provides a preparation method of the aqueous intermediate coat paint as described above, comprising the following steps:

[0017] Mix the acrylic resin, the amino resin, the polyurethane resin, the aqueous polyester resin composition, the pigment, and the deionized water; then add the organic solvent, and adjust the pH and viscosity to obtain the aqueous intermediate coat paint.

[0018] On the other hand, the present invention provides an aqueous composite coating, which is obtained by drying the aqueous intermediate coat paint, topcoat paint, and clear coat paint as described above that are sequentially sprayed.

[0019] On the other hand, the present invention provides an application of the intermediate coat paint as described above in the painting of automobiles.

[0020] The beneficial effects of the present invention are as follows:

[0021] In the aqueous polyester resin composition provided by the present invention, due to the presence of the selected and paired polyester resin A and polyester resin B, the aqueous polyester resin composition is particularly suitable for use in aqueous intermediate coats. After the aqueous intermediate coat containing the aqueous polyester resin composition of the present invention is used for automobile painting, on the basis of not reducing other properties of the obtained paint film (including sag resistance, pencil hardness, adhesion, impact resistance, non - stickiness, and appearance, etc.), it has relatively higher stone chip resistance than existing aqueous intermediate coat products. Detailed Embodiments

[0022] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0023] According to a specific embodiment of the present invention, there is provided an aqueous polyester resin composition, which comprises the following components:

[0024] Aqueous polyester resin A, with an acid value of 29 ± 2 mg KOH / g and a solids content of 68.7 ± 1.5 wt%;

[0025] Aqueous polyester resin B, with an acid value of 0 - 17 mg KOH / g or 70 - 80 mg KOH / g, and a solids content of 39 - 46 wt% or 95 - 100 wt%.

[0026] Exemplarily, in the molecular structure of the aqueous polyester resin A, the following groups are contained:

[0027] And terminal hydroxyl groups.

[0028] When this composition is used in an aqueous intermediate coat paint, the presence of in the structure of the aqueous polyester resin A can, while improving the rigidity of the paint, absorb the energy when the paint is impacted and reduce the impact on the paint film; wherein the carboxyl groups in the structure can improve the adhesion of the paint to the substrate; when the paint film is impacted by stones, the structure can, on the one hand, reduce the reaction time of the resin, and on the other hand, the cyclic polyester resin can improve the stone impact resistance of the paint; the terminal hydroxyl functional groups in the aqueous polyester resin A crosslink and cure into a film through reaction with resins such as polyurethane resin and amino resin in the paint, thereby improving the stone impact resistance of the paint. Exemplary aqueous polyester resin A includes but is not limited to polyester resin PRS - 1045 from Nippon Paint Co., Ltd.

[0029] In addition, an aqueous polyester resin composition formed by mixing and matching the aqueous polyester resin B with an acid value of 0-17 mg KOH / g or 70-80 mg KOH / g and a solid content of 39-46 wt% or 95-100 wt% with the above-mentioned aqueous polyester resin A is used for automotive painting in an aqueous intermediate coat. After painting the car, without reducing other properties of the obtained paint film (including sag resistance, pencil hardness, adhesion, impact resistance, non-stickiness, appearance, etc.), the stone chip resistance of the paint film is effectively improved. The mass ratio of the aqueous polyester resin A to the aqueous polyester resin B is preferably (3-5):(15-25). By controlling the dosage ratio of the two, the foregoing properties are better. Exemplarily, the mass ratio of the aqueous polyester resin A to the aqueous polyester resin B includes but is not limited to (3-5):20, 1:4-1:7, 1:4-1:5, 1:4, 1:5, 3:20, etc.

[0030] In some examples, the aqueous polyester resin B includes but is not limited to a polyester resin selected from one or more of the grades HH-2562, WATERSOLNP-6100, HK1495 modified polyester resin, and the aqueous polyester resin solution Baylon NC-3000.

[0031] According to another specific embodiment of the present invention, an aqueous intermediate coat paint is provided, which comprises the following components in parts by weight:

[0032] 5-12 parts of acrylic resin, 5-20 parts of amino resin, 1-6 parts of polyurethane resin, 18-30 parts of the above-mentioned aqueous polyester resin composition, 20-35 parts of pigment, 2-12 parts of organic solvent, and 5-30 parts of deionized water.

[0033] This aqueous intermediate coat paint can be used for automotive painting (as an intermediate coat). The paint film obtained by painting has good sag resistance, pencil hardness, adhesion, impact resistance, non-stickiness, appearance, and stone chip resistance.

[0034] In some examples, in the aqueous polyester resin composition, 3-5 parts of aqueous polyester resin A and 15-25 parts of aqueous polyester resin B are included.

[0035] The acrylic resins preferably applicable to this embodiment include but are not limited to one or more of EMA-1015S, EMA-1032, and EMA-1036. In some specific examples, the addition amount of the acrylic resin in this aqueous intermediate coat paint includes but is not limited to 5-10 parts, 5-7 parts, 7-12 parts, 7-10 parts, 7 parts, etc.

[0036] The amino resins preferably applicable to this embodiment include, but are not limited to, one or more of CYMEL 250, CYMEL 370, CYMEL 211, and CYMEL 325. In some specific examples, the addition amount of the amino resin in the waterborne intermediate coat paint includes, but is not limited to, 10 - 20 parts, 10 - 15 parts, 5 - 15 parts, 5 - 11 parts, 11 parts, etc.

[0037] The polyurethane resins preferably applicable to this embodiment include, but are not limited to, one or more of NEOREZ R - 9603 and UCOAT N - 800. In some specific examples, the addition amount of the polyurethane resin in the waterborne intermediate coat paint includes, but is not limited to, 1 - 4 parts, 2 - 6 parts, 2 - 4 parts, 3 - 6 parts, 4 - 6 parts, 4 parts, etc.

[0038] In this embodiment, there are no other requirements for the selection of pigments, and pigments conventionally used in waterborne intermediate coat paints can be selected. Exemplarily, the pigments include, but are not limited to, one or more of TiO2, iron oxide yellow, and carbon black. In some specific examples, the addition amount of the pigments in the waterborne intermediate coat paint includes, but is not limited to, 20 - 30 parts, 25 - 30 parts, 25 - 35 parts, 20 - 26 parts, 26 parts, etc.

[0039] In some examples, the organic solvent contains slow - drying solvents and alcohol - ether solvents. Exemplary slow - drying solvents include, but are not limited to, one or more of BDG, TK, and NMP. The addition amount of the slow - drying solvent includes, but is not limited to, 1 - 6 parts, 1 - 5 parts, 2 - 5 parts, 2 parts, etc. Exemplary alcohol - ether solvents include, but are not limited to, one or more of isooctanol and ethylene glycol isooctyl ether. The addition amount of the alcohol - ether solvent includes, but is not limited to, 1 - 6 parts, 1 - 5 parts, 2 - 4 parts, 4 - 6 parts, 4 parts, etc.

[0040] In some examples, the components of the waterborne intermediate coat paint further contain additives, and the additives contain one or more of dispersants, rheology modifiers, defoamers, and pH regulators.

[0041] In still other examples, in the waterborne intermediate coat paint, it contains 0.5 - 3 parts of dispersant, 0 - 2 parts of rheology modifier, 0 - 2 parts of defoamer, and 0 - 3 parts of pH regulator.

[0042] Preferably, the dispersants include, but are not limited to, one or more of 62J additive, BYK - 345, and BYK - 347. The addition amount of the exemplary dispersant includes, but is not limited to, 0.5 - 2 parts, 1 - 3 parts, 1 - 2 parts, 2 parts, etc.

[0043] Preferably, the rheology additive includes but is not limited to one or more of LAPONITE RD, ATTAGEL 50, and AQ-870. Exemplary addition amounts thereof may be 0 parts, 0.5 - 2 parts, 0.5 - 1 part, 0.6 - 1 part, 0.6 part, etc.

[0044] Preferably, the defoamer includes but is not limited to one or more of SN DEFOAMER 1341 and SURFYNOL 104A. Exemplary addition amounts thereof may be 0 parts, 0.5 - 2 parts, 1 - 2 parts, 2 parts, etc.

[0045] Preferably, the pH regulator includes but is not limited to dimethylethanolamine. Exemplary addition amounts thereof may be 0 parts, 0.5 - 3 parts, 0.5 - 2 parts, 0.5 - 1 part, 1 - 3 parts, 1 - 2 parts, 1 part, etc.

[0046] In some examples, in the aqueous primer paint, the total weight parts of each component is 100 parts.

[0047] According to another specific embodiment of the present invention, there is provided a preparation method of the aqueous primer paint as described above, and this preparation method includes the following steps:

[0048] Mix the acrylic resin, amino resin, polyurethane resin, aqueous polyester resin composition, pigment, and deionized water; then add an organic solvent, adjust the pH and viscosity to obtain the aqueous primer paint.

[0049] In some examples, the preparation method includes the following steps:

[0050] Add deionized water, add the rheology additive with stirring, after stirring for 15 minutes, sequentially add the pH regulator, part of the dispersant (40wt% - 80wt% of the total amount of the dispersant), and the defoamer under stirring, then add the pigment, after stirring for 15 minutes, add zirconia beads, and the addition amount is in a mass ratio of 1:1 to the above-mentioned mixed paint, and stir at high speed until the fineness of the sanding slurry ≤ 5μm;

[0051] After filtering out the zirconia beads, sequentially add the remaining dispersant, acrylic resin, amino resin, polyurethane resin, and aqueous polyester resin composition under stirring, after stirring for 15 minutes, add the slow-drying solvent, alcohol ether solvent, and defoamer, and adjust the pH and viscosity after color matching.

[0052] According to another specific embodiment of the present invention, there is provided an aqueous composite coating, which is obtained by drying the aqueous primer paint, topcoat paint, and clearcoat paint as described above sprayed in sequence.

[0053] In some examples, the preparation of the aqueous composite coating includes the following steps:

[0054] Spray the waterborne primer on the substrate, level it, pre-bake it, let it cool to room temperature, spray the waterborne topcoat, level it, pre-bake it; let it cool to room temperature (23 ± 2 °C), spray the clear coat, level it, and bake it to obtain the waterborne composite coating.

[0055] In some examples, the preparation of the waterborne composite coating includes the following steps:

[0056] Spray the waterborne primer on the substrate, level it for 3 minutes, pre-bake it at 80 °C for 5 minutes, let it cool to room temperature (23 ± 2 °C), spray the waterborne topcoat, level it for 3 minutes, pre-bake it at 80 °C for 5 minutes; let it cool to room temperature (23 ± 2 °C), spray the clear coat, level it for 7 minutes, and bake it at 140 °C to obtain the waterborne composite coating.

[0057] Exemplarily, the substrate is an electrophoretic plate (preferably with a size of 70 mm * 150 mm), an automotive metal substrate.

[0058] Exemplarily, the dry film thickness of the sprayed primer is 20 ± 2 μm, the dry film thickness of the topcoat is 13 ± 2 μm, and the dry film thickness of the clear coat is 35 ± 5 μm.

[0059] According to another specific embodiment of the present invention, there is provided the application of the above-mentioned primer in the painting of automobiles.

[0060] The technical solutions of the present invention are described below in conjunction with some specific examples:

[0061] Example 1

[0062] A waterborne primer, the components and dosages of its raw materials are shown in Table 1. The preparation method of this waterborne primer includes the following steps:

[0063] Add deionized water, add a rheology aid under stirring, stir for 15 minutes, then sequentially add a pH regulator, a 60 wt% dispersant, and an antifoaming agent under stirring, then add pigments, stir for 15 minutes, add zirconia beads, and the addition amount is 1:1 with the mass of the above-mentioned mixed coating, and stir at high speed until the fineness of the sanding slurry ≤ 5 μm;

[0064] After filtering out the zirconia beads, sequentially add the remaining 40 wt% dispersant, acrylic resin, amino resin, polyurethane resin, waterborne polyester resin A, and waterborne polyester resin B under stirring, stir for 15 minutes, then add a slow-drying solvent, an alcohol ether solvent, and an antifoaming agent, adjust the pH and viscosity after color matching to obtain the waterborne primer.

[0065] The application of this waterborne primer in automotive painting:

[0066] Spray the waterborne intermediate paint on a clean electrophoresis plate (70mm * 150mm), level for 3 minutes, pre-bake at 80°C for 5 minutes, let it cool to room temperature (23 ± 2°C), spray the AR-3020 209 waterborne topcoat, level for 3 minutes, pre-bake at 80°C for 5 minutes; let it cool to room temperature (23 ± 2°C), spray the MAC O-1860-X clear coat, after leveling for 7 minutes, dry at 140°C to obtain a composite coating. The dry film thickness of each coating layer is as follows:

[0067] Waterborne intermediate paint 20 ± 2μm;

[0068] Waterborne topcoat 13 ± 2μm;

[0069] Clear coat 35 ± 5μm.

[0070] Examples 2 - 3

[0071] The waterborne intermediate paint, the components and their dosages in the raw materials are shown in Table 1. The preparation method of this waterborne intermediate paint and its application method in automotive painting are the same as those in Example 1.

[0072] Comparative Examples 1 - 6

[0073] The waterborne intermediate paint, the components and their dosages in the raw materials are shown in Table 1. The preparation method of this waterborne intermediate paint and its application method in automotive painting are the same as those in Example 1.

[0074] Among them, in Comparative Example 5 6306SS-60 resin (Zeneca Resin), acid value: 23.6 - 27.5mg KOH / g; in Comparative Example 6, ETERKYD BK5434 (Changxing Materials Industry Co., Ltd.), acid value: 21 - 25mg KOH / g.

[0075] Performance testing of the composite coating:

[0076] Stone chip resistance: Q / SQR.04.361-2005;

[0077] Sagging resistance: GB / T 9264-2012;

[0078] Pencil hardness: GB / T 6739-2022;

[0079] Adhesion: GB-T 31586.2-2015;

[0080] Impact resistance: GB 20624.1-2006;

[0081] Non-stickiness: Wrap a 500g weight with gauze and place it on the tested coating, put it in an oven at 70 ± 2°C and let it stand for 2 hours, take it out and let it cool to room temperature, remove the weight with the sandcloth, and observe whether there are imprints on the paint film surface;

[0082] Appearance: BYK WAVE-SCAN.

[0083] The coating properties obtained from the above examples and comparative examples are shown in Table 1 below (in Table 1, the content of each component is in mass percentage, wt%).

[0084] Table 1

[0085]

[0086]

[0087] In the present invention, the above-mentioned properties of the coatings were also tested when the aqueous polyester resin B was HH-2562, HK1495 modified polyester resin or aqueous polyester resin solution Bayhydrol NC-3000 respectively compared with Example 1, and the results all met the requirements.

[0088] Obviously, the above examples of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation modes of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation modes here. Any obvious changes or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An aqueous polyester resin composition, characterized in that, It comprises the following components: Waterborne polyester resin A with an acid value of 29 ± 2 mg KOH / g and a solids content of 68.7 ± 1.5 wt%; Waterborne polyester resin B with an acid value of 0 - 17 mg KOH / g or 70 - 80 mg KOH / g and a solids content of 39 - 46 wt% or 95 - 100 wt%.

2. The aqueous polyester resin composition according to claim 1, characterized in that, In the molecular structure of the waterborne polyester resin A, it contains the following groups: and terminal hydroxyl groups.

3. The aqueous polyester resin composition according to claim 1, characterized in that, The mass ratio of the waterborne polyester resin A to the waterborne polyester resin B is (3 - 5):(15 - 25).

4. An aqueous intermediate coat paint, characterized in that, It comprises the following components in parts by weight: 5 - 12 parts of acrylic resin, 5 - 20 parts of amino resin, 1 - 6 parts of polyurethane resin, 18 - 30 parts of the waterborne polyester resin composition according to any one of claims 1 - 3, 20 - 35 parts of pigment, 2 - 12 parts of organic solvent, and 5 - 30 parts of deionized water.

5. The aqueous intermediate coat paint according to claim 4, characterized in that, In the waterborne polyester resin composition, it contains 3 - 5 parts of waterborne polyester resin A and 15 - 25 parts of waterborne polyester resin B.

6. The aqueous intermediate coat paint according to claim 4, characterized in that, It further comprises additives, and the additives contain one or more of a dispersant, a rheology aid, an antifoaming agent, and a pH regulator.

7. The aqueous intermediate coat paint according to claim 6, characterized in that, In the waterborne intermediate paint, it contains 0.5 - 3 parts of dispersant, 0 - 2 parts of rheology aid, 0 - 2 parts of antifoaming agent, and 0 - 3 parts of pH regulator.

8. A method for preparing the aqueous intermediate coat paint according to any one of claims 4 - 7, characterized in that, It includes the following steps: Mix the acrylic resin, amino resin, polyurethane resin, waterborne polyester resin composition, pigment, and deionized water; then add the organic solvent and adjust the pH and viscosity to obtain the waterborne intermediate paint.

9. An aqueous composite coating, characterized in that, It is obtained by drying the waterborne intermediate paint, topcoat, and clearcoat sprayed in sequence according to any one of claims 4 - 7.

10. Use of the intermediate coat paint according to any one of claims 4 - 7 in the painting of automobiles.

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