Varnish with high interlayer adhesive force and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to the field of IPC C09F, and more particularly relates to varnish with high interlayer adhesive force and a preparation method of the varnish. The water-based ink comprises the following components in parts by weight: 40-60 parts of a hydroxyl acrylic acid dispersion, 30-40 parts of a polyurethane acrylic acid dispersion, 10-15 parts of a solvent, 3-6 parts of a light stabilizer and 0.5-3 parts of an auxiliary agent. The varnish prepared by the invention can keep 0-level adhesive force for a long time when being applied to a coating, and can pass 1500h salt mist resistance and weather resistance tests and 48h 40 DEG C water resistance tests.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to the field of IPC C09F, and more specifically to a varnish with high inter-layer adhesion and a preparation method thereof. Background Art

[0002] Varnish is a coating composed of resin as the main film-forming substance and solvent. As an important coating, it can be used for the coating of furniture, floors, doors and windows, and automobiles, and has decorative and protective functions. However, while varnish provides excellent aesthetic effects, it is also easy to reduce its aesthetic effects due to external damage, and in more serious cases, it loses its decorative and protective functions. To ensure the clear texture of the substrate and combine the on-site construction process, it is necessary to spray the topcoat directly on the unpolished surface of the primer coating. Since the surface of the primer coating is very smooth, it is difficult for general water-based acrylic coatings to ensure good interlayer adhesion or achieve the required adhesion, and it is also difficult to have both weather resistance and water resistance.

[0003] Chinese invention patent CN112694827A discloses a water-based UV varnish for hot stamping of ABS substrate, which is composed of the following components: 3-4 functional water-based polyurethane acrylate dispersion, hydroxyl-containing acrylic emulsion, self-drying water-based polyurethane dispersion, deionized water, film-forming aid, photoinitiator, water-based wetting agent, water-based defoamer, water-based thickener and ammonia neutralizer. The water-based UV varnish uses water-based polyurethane acrylate dispersion as the main resin, and is matched with hydroxyl-containing acrylic emulsion and self-drying water-based polyurethane dispersion to increase the overall flexibility and water resistance of the coating film. The coating film still maintains good adhesion to the hot stamping layer after being soaked in pure water and alcohol, but the varnish of the invention does not involve the compounding of the smooth primer surface, nor does it have weather resistance. Summary of the invention

[0004] The first aspect of the present invention provides a varnish with high inter-layer adhesion, which comprises, by weight, 40-60 parts of hydroxyl acrylic dispersion, 30-40 parts of polyurethane acrylic dispersion, 10-15 parts of solvent, 3-6 parts of light stabilizer, and 0.5-3 parts of auxiliary agent.

[0005] The weight ratio of the hydroxy acrylic dispersion to the polyurethane acrylic dispersion is 1:(0.5-1.2).

[0006] Preferably, the weight ratio of the hydroxyl acrylic dispersion to the polyurethane acrylic dispersion is 1:(0.8-1.2).

[0007] The present application has found that the weight ratio of the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion is 1: (0.5-1.2), and the hydroxyl content in the hydroxyl acrylic dispersion is 1-7wt%, so that the adhesion of the prepared varnish can reach level 1-2, and at the same time has a certain glossiness. It may be that under normal circumstances, due to the incompatibility of the two types of resins, their blending system is prone to phase separation, resulting in poor performance of the mixture. The present application selects a hydroxyl acrylic dispersion with a specific hydroxyl content of 1-7wt%, and constructs a specific physical network structure with the soft segment of the polyurethane acrylic dispersion, reducing the formation of differential phases. Further research has found that the weight ratio of the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion is 1: (0.8-1.2), and the adhesion of the prepared varnish can be maintained at level 0 for a long time.

[0008] The hydroxyl content of the hydroxy acrylic dispersion is 1-7 wt %.

[0009] Preferably, the hydroxyl content in the hydroxylated acrylic dispersion is 1-4 wt %.

[0010] The light stabilizer includes hindered amine light stabilizer and triazine light stabilizer.

[0011] Preferably, the hindered amine light stabilizer includes at least one of the following brands: Tinuvin 622, Tinuvin 770, Tinuvin 944, Tinuvin 783, Tinuvin 791, Tinuvin 3853, Tinuvin 292 and Tinuvin 123.

[0012] Preferably, the triazine light stabilizer comprises at least one of the following brands: Tinuvin 400, Tinuvin 405, Tinuvin 460 and Tinuvin 479.

[0013] Preferably, the weight ratio of the hindered amine light stabilizer to the triazine light stabilizer is 1:(1.5-3).

[0014] More preferably, the weight ratio of the hindered amine light stabilizer to the triazine light stabilizer is 1:(2-3).

[0015] The auxiliary agent includes at least one of a wetting agent, a thickener and a defoaming agent.

[0016] Preferably, the auxiliary agent includes a wetting agent, a thickener and a defoaming agent.

[0017] Preferably, the wetting agent includes at least one of Digo 4100, Digo 500, Digo 270, Puwei W138, and Puwei W118.

[0018] Preferably, the thickener includes one or more of carboxymethyl cellulose, BP-188X, Coapur 830W, Mingling PUR44, Hemmings HX6008, BYK420, ViscoPlus3060, and SN-THICKENER 621N.

[0019] Preferably, the defoaming agent includes one or more of BYK-028 from BYK of Germany, Efka 2722, Digo AIREX 900, SN154 from Nopco and A10 from BASF.

[0020] The solvent includes at least one of DPM (dipropylene glycol methyl ether), DPnB (dipropylene glycol butyl ether), DMM (dipropylene glycol dimethyl ether), DB (ethylene glycol monobutyl ether), and deionized water.

[0021] Preferably, the solvent comprises DPM, DPnB and deionized water, and the weight ratio of DPM, DPnB and deionized water is 1:(1.5-3):(0.5-1.8).

[0022] Further preferably, the weight ratio of DPM, DPnB and deionized water is 1:(2-3):(0.5-1).

[0023] A second aspect of the present invention provides a method for preparing a varnish with high inter-layer adhesion, comprising the following steps:

[0024] S1, mixing the light stabilizer and the solvent uniformly to obtain a first mixture;

[0025] S2, stirring the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion evenly, and then mixing them with the first mixture to obtain a second mixture;

[0026] S3, adding a wetting agent, a thickener and a defoaming agent to the second mixture in sequence, stirring evenly, and obtaining the product.

[0027] Beneficial Effects

[0028] 1. The weight ratio of hydroxyl acrylic dispersion to polyurethane acrylic dispersion is 1: (0.5-1.2), and the hydroxyl content in the hydroxyl acrylic dispersion is 1-7wt%, so that the adhesion of the prepared varnish can reach

[0029] Level 1-2, with a certain glossiness.

[0030] 2. The weight ratio of the hydroxy acrylic dispersion to the polyurethane acrylic dispersion is 1:(0.8-1.2), and the adhesion of the prepared varnish can be maintained at level 0 for a long time.

[0031] 3. The hydroxyl content in the hydroxy acrylic dispersion is 1-7 wt %, which can further improve the water resistance of the film layer.

[0032] 4. The light stabilizer includes a hindered amine light stabilizer and a triazine light stabilizer, and the weight ratio of the hindered amine light stabilizer to the triazine light stabilizer is 1:(1.5-3), which can pass the 1500h weather resistance test and achieve excellent stability.

[0033] 5. The solvent includes DPM, DPnB and deionized water, wherein the weight ratio of DPM, DPnB and deionized water is 1:(1.5-3):(0.5-1.8), which can further improve the film-forming performance, and on the basis of the film layer having excellent mechanical properties, further improve the glossiness of the film layer to greater than 90°. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a sample picture after the adhesion test of Example 3. DETAILED DESCRIPTION

[0035] Examples 1-3

[0036] A varnish with high inter-layer adhesion, the components in parts by weight are shown in Table 1:

[0037] Table 1

[0038]

[0039]

[0040] A method for preparing a varnish with high inter-layer adhesion comprises the following steps:

[0041] S1, mixing the light stabilizer and the solvent uniformly to obtain a first mixture;

[0042] S2, stirring the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion evenly, and then mixing them with the first mixture to obtain a second mixture;

[0043] S3, adding a wetting agent, a thickener and a defoaming agent to the second mixture in sequence, stirring evenly, and obtaining the product.

[0044] Comparative Examples 1-7

[0045] A varnish, the components of which are shown in Table 2 in parts by weight:

[0046] Table 2

[0047]

[0048]

[0049] Among them, comparative example 1-2

[0050] A method for preparing a varnish comprises the following steps:

[0051] S1, mixing the light stabilizer and the solvent uniformly to obtain a first mixture;

[0052] S2, stirring the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion evenly, and then mixing them with the first mixture to obtain a second mixture;

[0053] S3, adding a wetting agent, a thickener and a defoaming agent to the second mixture in sequence, stirring evenly, and obtaining the product.

[0054] Among them, comparative examples 3-7

[0055] A method for preparing a varnish comprises the following steps:

[0056] S1, mixing the light stabilizer and the solvent uniformly to obtain a first mixture;

[0057] S2, uniformly mixing the hydroxylated acrylic acid dispersion with the first mixture to obtain a second mixture;

[0058] S3, adding a wetting agent, a thickener and a defoaming agent to the second mixture in sequence, stirring evenly, and obtaining the product.

[0059] Performance Testing Methods

[0060] After cleaning the impurities and oil stains on the surface of the material, the primer was sprayed, and the primer film thickness was about 60 μm. After the spraying was completed, it was placed in a ventilated, dry and suitable temperature environment to dry for 48 hours, and then the varnish in the embodiment and the comparative example was sprayed (wherein the curing agent was Bayhydur 306, and the weight ratio of the curing agent to the varnish was 1:3). After the spraying was completed, it was placed in the same environment to dry for 7 days before testing. The test data is listed in Table 3.

[0061] 1. Minimum gloss at 20° and 60° angles: According to the national standard GB / T 9754-2007, use a gloss meter that meets the standard to test the gloss, measure multiple points multiple times, and record the minimum gloss at 20° and 60° angles. ≥90 is qualified, otherwise it is unqualified.

[0062] 2.40℃, 48h water resistance test: According to the national standard GB / T 5209, a 48h water resistance test is carried out at a constant temperature of 40±1℃.

[0063] 3. Adhesion: According to the national standard GB / T 9286, a cross-cut adhesion test was performed according to the standard. The samples after the adhesion test in Example 3 were as follows: Figure 1 As shown, excellent adhesion is demonstrated.

[0064] 4. Weather resistance: According to the national standard GB / T 14522-2008, the test is 1500h, the gloss loss rate is ≤15%, and the color difference change is ≤3% to pass, otherwise it is unqualified.

[0065] Performance test data

[0066] Table 3

[0067]

Claims

1. A varnish with high inter-layer adhesion, characterized in that: The components include, by weight: 40-60 parts of hydroxyl acrylic dispersion, 30-40 parts of polyurethane acrylic dispersion, 10-15 parts of solvent, 3-6 parts of light stabilizer, and 0.5-3 parts of auxiliary agent.

2. The varnish with high inter-layer adhesion according to claim 1, characterized in that: The weight ratio of the hydroxy acrylic dispersion to the polyurethane acrylic dispersion is 1:(0.5-1.2).

3. The varnish with high inter-layer adhesion according to claim 2, characterized in that: The weight ratio of the hydroxy acrylic dispersion to the polyurethane acrylic dispersion is 1:(0.8-1.2).

4. The varnish with high inter-layer adhesion according to claim 3, characterized in that: The hydroxyl content of the hydroxy acrylic dispersion is 1-7 wt %.

5. The varnish with high inter-layer adhesion according to claim 1 or 4, characterized in that: The light stabilizer includes hindered amine light stabilizer and triazine light stabilizer.

6. The varnish with high inter-layer adhesion according to claim 5, characterized in that: The weight ratio of the hindered amine light stabilizer to the triazine light stabilizer is 1:(1.5-3).

7. The varnish with high inter-layer adhesion according to claim 6, characterized in that: The auxiliary agent includes at least one of a wetting agent, a thickener and a defoaming agent.

8. The varnish with high inter-layer adhesion according to claim 7, characterized in that: The solvent includes at least one of DPM, DPnB, DMM, DB, and deionized water.

9. The varnish with high inter-layer adhesion according to claim 8, characterized in that: The solvent includes DPM, DPnB and deionized water, and the weight ratio of DPM, DPnB and deionized water is 1: (1.5-3): (0.5-1.8)。 10. A method for preparing a varnish with high inter-layer adhesion according to any one of claims 6 to 8, characterized in that: The following steps are involved: S1, mixing the light stabilizer and the solvent uniformly to obtain a first mixture; S2, stirring the hydroxyl acrylic dispersion and the polyurethane acrylic dispersion evenly, and then mixing them with the first mixture to obtain a second mixture; S3, adding a wetting agent, a thickener and a defoaming agent to the second mixture in sequence, stirring evenly, and obtaining the product.

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