Waterborne acrylic polyurethane finish paint

Abstract

The invention relates to the technical field of finish paint, and discloses waterborne acrylic polyurethane finish paint which is a two-component system and comprises a main agent and a curing agent. According to the scheme, the water-based hydroxyl acrylic resin with the specific hydroxyl value of 100 mgKOH / g is preferably selected and compounded with the water-based polycarbonate type polyurethane dispersion with the solid content of 35%-45%, the balance hardness and flexibility are improved, the pigment filler, the cosolvent, the dispersing agent, the wetting agent, the defoaming agent, the rheological agent and the light stabilizer are added in proportion to obtain the main agent, and the main agent is added into the water-based hydroxyl acrylic resin to obtain the water-based polyurethane coating. Meanwhile, hydrophilic aliphatic polyisocyanate and propylene glycol diacetate are mixed to obtain a curing agent, and the main agent and the curing agent are matched according to the weight percentage of 4: 1, so that the acid resistance, alkali resistance and water resistance of a paint film are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of topcoat technology, and in particular to a water-based acrylic polyurethane topcoat. Background Technology

[0002] Waterborne acrylic polyurethane topcoat is an environmentally friendly two-component industrial coating. Due to its excellent weather resistance and high mechanical properties, it is widely used in automobiles, construction machinery, and building steel structures. However, existing waterborne acrylic polyurethane topcoats are prone to chalking and loss of gloss under long-term outdoor exposure, and the crosslinking density is insufficient, resulting in low film hardness and poor acid, alkali and water resistance. Summary of the Invention

[0003] To address the aforementioned problems of existing waterborne acrylic polyurethane topcoats exhibiting chalking and gloss loss under prolonged outdoor exposure, as well as insufficient crosslinking density leading to low film hardness and poor acid, alkali, and water resistance, this application provides a waterborne acrylic polyurethane topcoat.

[0004] This application provides a water-based acrylic polyurethane topcoat using the following technical solution:

[0005] A water-based acrylic polyurethane topcoat, wherein the topcoat is a two-component system comprising a base agent and a curing agent, and the base agent comprises the following components by weight percentage:

[0006] 40-60% aqueous hydroxyl-containing acrylic dispersion;

[0007] 10-20% water-based polycarbonate-containing polyurethane dispersion;

[0008] Pigments and fillers 15-25%;

[0009] 3-8% co-solvent;

[0010] Dispersant 0.5-1.5%;

[0011] Wetting agent 0.1-0.5%;

[0012] Defoamer 0.1-0.5%;

[0013] Rheology modifier 0.5-1.5%;

[0014] Light stabilizer 0.5-1.5%;

[0015] Deionized water 5-15%;

[0016] The curing agent, by weight percentage, comprises the following components:

[0017] Hydrophilic aliphatic polyisocyanates 70-90%;

[0018] Propylene glycol diacetate 10-30%.

[0019] The ratio of main agent to curing agent by weight percentage is 4:1.

[0020] Preferably, the hydroxyl value of the aqueous hydroxyl-containing acrylic dispersion is 100 mgKOH / g.

[0021] Preferably, the solid content of the waterborne polycarbonate polyurethane dispersion is 35%-45%.

[0022] Preferably, the pigment or filler is one of rutile titanium dioxide, barium sulfate, and mica powder, specifically rutile titanium dioxide.

[0023] Preferably, the co-solvent is a mixture of dipropylene glycol methyl ether and dipropylene glycol butyl ether in a mass ratio of 3:1.

[0024] Preferably, the light stabilizer is a mixture of hindered amine light stabilizer and benzotriazole ultraviolet absorber in a mass ratio of 2:1.

[0025] Preferably, the hydrophilic aliphatic polyisocyanate is a hexamethylene diisocyanate trimer, and the hexamethylene diisocyanate trimer has an isocyanate group content of 21.5%.

[0026] In summary, this application includes the following beneficial technical effects: by selecting a waterborne hydroxyl acrylic resin with a specific hydroxyl value of 100 mgKOH / g and compounding it with a waterborne polycarbonate-type polyurethane dispersion with a solid content of 35%-45%, the balanced hardness and flexibility are improved. The main agent is obtained by adding pigments, fillers, cosolvents, dispersants, wetting agents, defoamers, rheology modifiers, and light stabilizers in proportion. At the same time, a curing agent is obtained by mixing hydrophilic aliphatic polyisocyanate and propylene glycol diacetate. The main agent and curing agent are combined in a weight ratio of 4:1, which significantly improves the acid resistance, alkali resistance, and water resistance of the coating film. Detailed Implementation

[0027] The following provides a further detailed description of this application.

[0028] Example 1:

[0029] A water-based acrylic polyurethane topcoat, the topcoat being a two-component system comprising a base agent and a curing agent, wherein the base agent, by weight percentage, comprises the following components:

[0030] 40-60% aqueous hydroxyl-containing acrylic dispersion;

[0031] 10-20% water-based polycarbonate-containing polyurethane dispersion;

[0032] Pigments and fillers 15-25%;

[0033] 3-8% co-solvent;

[0034] Dispersant 0.5-1.5%;

[0035] Wetting agent 0.1-0.5%;

[0036] Defoamer 0.1-0.5%;

[0037] Rheology modifier 0.5-1.5%;

[0038] Light stabilizer 0.5-1.5%;

[0039] Deionized water 5-15%;

[0040] The aqueous hydroxyl-containing acrylic dispersion has a hydroxyl value of 100 mgKOH / g, and the aqueous polycarbonate-type polyurethane dispersion has a solid content of 35%-45%, which can effectively improve the flexibility and balanced hardness of the paint film. The pigments and fillers are one of rutile titanium dioxide, barium sulfate, and mica powder. Specifically, the pigments and fillers are rutile titanium dioxide, which can effectively improve acid resistance, alkali resistance, and water resistance. The cosolvent is a mixture of dipropylene glycol methyl ether and dipropylene glycol butyl ether in a mass ratio of 3:1, which can promote resin dissolution and compatibility, and at the same time improve film-forming properties. The light stabilizer is a compound of hindered amine light stabilizer and benzotriazole ultraviolet absorber in a mass ratio of 2:1, which is used to delay or inhibit the photoaging process caused by ultraviolet (UV) irradiation.

[0041] By weight percentage, the curing agent consists of the following components:

[0042] Hydrophilic aliphatic polyisocyanates 70-90%;

[0043] Propylene glycol diacetate 10-30%;

[0044] Among them, the hydrophilic aliphatic polyisocyanate is a hexamethylene diisocyanate trimer, and the isocyanate group content of the hexamethylene diisocyanate trimer is 21.5%;

[0045] The ratio of main agent to curing agent by weight percentage is 4:1.

[0046] The following describes the preparation method of the waterborne acrylic polyurethane topcoat of the present invention (each component is added in proportion in each of the following steps):

[0047] Step 1: Mix deionized water, dispersant, wetting agent, and part of the defoamer, and stir at 800 rpm for 10 minutes;

[0048] Step 2: Add rutile titanium dioxide and disperse and grind it at 1000 rpm for 10 minutes to make its fineness ≤20μm;

[0049] Step 3: Add water-based hydroxyl-containing acrylic dispersion, water-based polycarbonate-containing polyurethane dispersion, cosolvent, rheology modifier, light stabilizer and remaining defoamer, stir and mix at 1000 rpm for 20 minutes, finally filter and obtain the main agent;

[0050] Step 4: Mix the hydrophilic aliphatic polyisocyanate and propylene glycol diacetate at 800 rpm for 10 minutes to obtain the curing agent;

[0051] Step 5: Mix the main agent and curing agent in a 4:1 ratio, add an appropriate amount of deionized water to adjust the viscosity for application, stir at 500 rpm for 5 minutes and then proceed with the application.

[0052] The topcoat of Example 1 was applied to the surface of an iron plate with dimensions of 1000mm (length) x 1000mm (width) x 10mm (height) and cured indoors for one week. Performance tests were conducted on aspects such as appearance, pencil hardness, gloss, adhesion, water resistance, acid resistance, alkali resistance, and weather resistance. The performance data results are shown in Table 1.

[0053] Table 1

[0054] Performance testing Example 1 Appearance Smooth and flat, without shrinkage cavities Pencil hardness 2H gloss ≥92 Adhesion Level 0 Water resistance The surface paint film does not bubble, lose its gloss, or peel. acid resistance The surface paint film does not bubble, lose its gloss, or peel. Alkali resistance The surface paint film does not bubble, lose its gloss, or peel. Weather resistance The surface paint film does not bubble, lose its gloss, or peel.

[0055] The foregoing description of an exemplary embodiment of a waterborne acrylic polyurethane topcoat provided by this disclosure refers to preferred embodiments. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the spirit of this disclosure, and various combinations can be made to the various technical features and structures proposed in this disclosure without exceeding the protection scope of this disclosure, which is determined by the appended claims.

Claims

1. A water-based acrylic polyurethane topcoat, wherein the topcoat is a two-component system comprising a base agent and a curing agent, characterized in that, The main agent, by weight percentage, comprises the following components: 40-60% aqueous hydroxyl-containing acrylic dispersion; 10-20% water-based polycarbonate-containing polyurethane dispersion; Pigments and fillers 15-25%; 3-8% co-solvent; Dispersant 0.5-1.5%; Wetting agent 0.1-0.5%; Defoamer 0.1-0.5%; Rheology modifier 0.5-1.5%; Light stabilizer 0.5-1.5%; Deionized water 5-15%; The curing agent, by weight percentage, comprises the following components: Hydrophilic aliphatic polyisocyanates 70-90%; Propylene glycol diacetate 10-30%. The ratio of main agent to curing agent by weight percentage is 4:

1.

2. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The hydroxyl value of the aqueous hydroxyl-containing acrylic dispersion is 100 mgKOH / g.

3. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The solid content of the waterborne polycarbonate-type polyurethane dispersion is 35%-45%.

4. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The pigment and filler are one of rutile titanium dioxide, barium sulfate, and mica powder, specifically rutile titanium dioxide.

5. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The cosolvent is a mixture of dipropylene glycol methyl ether and dipropylene glycol butyl ether in a mass ratio of 3:

1.

6. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The light stabilizer is a mixture of hindered amine light stabilizer and benzotriazole ultraviolet absorber in a mass ratio of 2:

1.

7. The water-based acrylic polyurethane topcoat according to claim 1, characterized in that: The hydrophilic aliphatic polyisocyanate is a hexamethylene diisocyanate trimer, and the hexamethylene diisocyanate trimer has an isocyanate group content of 21.5%.