Varnish with long activation period and application 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 a long activation period and application of the varnish. Comprising a component A and a component B. The component A comprises, by weight, 25-50 parts of a hydroxy acrylic dispersion, 25-45 parts of a hydroxy acrylic emulsion, 10-20 parts of a coalescing agent and 5-15 parts of deionized water, and the component B comprises a curing agent. The weight ratio of the hydroxyl acrylic acid dispersion to the hydroxyl acrylic acid emulsion is 1: (0.5-1.2), the hydroxyl content in the hydroxyl acrylic acid emulsion is 1-3wt%, the hydroxyl content in the hydroxyl acrylic acid dispersion is 2-6wt%, an ultra-long activation period of more than 4 hours can be achieved, and the construction efficiency is improved; the weight ratio of the hydroxyl acrylic acid dispersion to the hydroxyl acrylic acid emulsion is 1: (0.9-1.2), so that the hardness and weather resistance of a paint film can be improved, and the use requirements of rail transit products are met.

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 a long activation period and application thereof. Background Art

[0002] The activation period is also called the mixing validity period. Its specific meaning refers to the period from when the multiple components of the coating are mixed to when they cannot be used. The activation period of solvent-based PU two-component coatings usually refers to the period from the time the paint is mixed, when the viscosity of the paint increases but does not affect the construction, and has no significant effect on the film-forming process and the performance of the paint film. The long activation period is to allow workers to have a long construction window during construction. Most of the rail transit construction requires the whole vehicle to be sprayed, and the product activation period must ensure that the workers can complete the spraying in one go. The varnish used in rail transit has strict performance requirements, which not only meets the performance requirements of rail transit coatings, but is also suitable for long-term construction by on-site workers. It is also necessary to ensure a high-gloss and smooth appearance, as well as excellent water resistance, weather resistance, and antifreeze properties. While ensuring these, this product also has the advantages of high hardness and high activation period.

[0003] Chinese invention patent CN101914185A is prepared by a step-by-step free radical polymerization solution polymerization method, by using a specific type of initiator, assisted by a chain transfer agent, and reacting at a higher polymerization temperature. The prepared water-dispersible resin has a core-shell structure, including a carboxyl-free, weakly hydrophilic core layer and a carboxyl-rich, strongly hydrophilic shell layer. The obtained hydroxylated acrylic acid aqueous dispersion has the characteristics of low solvent content, low acid value, high solid content, and low viscosity, and has excellent film properties for two-component waterborne polyurethane coatings. However, the invention does not solve the problem of the difficulty in balancing the mechanical properties of the coating and the applicable period. Summary of the invention

[0004] The first aspect of the present invention provides a varnish with a long activation period, comprising a component A and a component B, wherein the component A comprises, by weight, 25-50 parts of a hydroxylated acrylic dispersion, 25-45 parts of a hydroxylated acrylic emulsion, 10-20 parts of a film-forming aid, and 5-15 parts of deionized water, and the component B comprises a curing agent.

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

[0006] Preferably, the weight ratio of the hydroxylated acrylic dispersion to the hydroxylated acrylic emulsion is 1:(0.9-1.2).

[0007] Further preferably, the weight ratio of the hydroxylated acrylic dispersion to the hydroxylated acrylic emulsion is 7:(7-8).

[0008] Preferably, the hydroxy acrylic emulsion comprises an anionic emulsion with a pH of 6-8.

[0009] The hydroxyl content of the hydroxy acrylic emulsion is 1-3 wt %, and the hydroxyl content of the hydroxy acrylic dispersion is 2-6 wt %.

[0010] Preferably, the hydroxyl content in the hydroxylated acrylic emulsion is 2-3 wt %, and the hydroxyl content in the hydroxylated acrylic dispersion is 2-4 wt %.

[0011] The present application has found that the weight ratio of the hydroxyl acrylic dispersion and the hydroxyl acrylic emulsion is 1:(0.5-1.2), and the hydroxyl content in the hydroxyl acrylic emulsion is 1-3wt%, and the hydroxyl content in the hydroxyl acrylic dispersion is 2-6wt%, which can achieve an ultra-long activation period of more than 4 hours, thereby improving the construction efficiency. It may be that the specific hydroxyl content and distribution increase the activation energy of the reaction with the curing agent. Further studies have found that the weight ratio of the hydroxyl acrylic dispersion and the hydroxyl acrylic emulsion is 1:(0.9-1.2), which can improve the hardness and weather resistance of the paint film. It may be that the specific polymer network structure increases the crosslinking density and reduces the shrinkage rate of the system. Further studies have found that the content of the film-forming aid in component A is 10-20wt%, which can further improve the glossiness while maintaining the hardness of the paint film. It may be that the film-forming aid affects the fluidity and drying speed during the film-forming process, thereby affecting the directional arrangement of the molecular structure of the surface layer of the paint film.

[0012] The viscosity of the hydroxylated acrylic dispersion at 25° C. is 500-4500 mPa·s.

[0013] The varnish component also includes a light stabilizer, a defoamer, an anti-sagging aid and a wetting agent.

[0014] The defoaming agent includes a polymer defoaming agent and an acetylene glycol defoaming agent.

[0015] Preferably, the weight ratio of the polymer defoamer to the acetylene glycol defoamer is 1:(0.8-1.2).

[0016] Preferably, the weight ratio of the polymer defoamer to the acetylene glycol defoamer is 1:1.

[0017] Further preferably, the polymer defoamer comprises a polymer defoamer that does not contain silicone, preferably at least one of the following BYK chemical models: BYK-A555, BYK-012, BYK-057, BYK-1790, BYK-011, BYK-051N.

[0018] Preferably, the acetylene glycol defoamer comprises at least one of the following gas chemistry models: 104E, 110D and SURFYNOLD106.

[0019] The content of the film-forming aid in component A is 10-20 wt%.

[0020] Preferably, the content of the film-forming aid in component A is 12-17 wt %.

[0021] The film-forming aid comprises DPM (dipropylene glycol methyl ether) and DPnB (dipropylene glycol butyl ether), and the weight ratio of DPM to DPnB is 1:(1.5-3).

[0022] The weight ratio of DPM to DPnB is 1:(2-3).

[0023] The weight ratio of the DPM to DPnB is 1:2.

[0024] Preferably, the anti-sagging aid comprises a modified urea solution.

[0025] A second aspect of the present invention provides an application of a varnish with a long activation period, which is applied to rail transportation.

[0026] Beneficial Effects

[0027] 1. The weight ratio of the hydroxyl acrylic dispersion to the hydroxyl acrylic emulsion is 1:(0.5-1.2), and the hydroxyl content in the hydroxyl acrylic emulsion is 1-3wt%, and the hydroxyl content in the hydroxyl acrylic dispersion is

[0028] 2-6wt%, can achieve an ultra-long activation period of more than 4 hours, improving construction efficiency.

[0029] 2. The weight ratio of hydroxyl acrylic dispersion and hydroxyl acrylic emulsion is 1:(0.9-1.2), which can improve the hardness and weather resistance of the paint film and meet the use requirements of rail transit products.

[0030] 3. The content of film-forming aid in component A is 10-20wt%, which can further improve the glossiness while maintaining the hardness of the paint film.

[0031] 4. The defoaming agent includes a polymer defoaming agent and an acetylene glycol defoaming agent, and the weight ratio of the polymer defoaming agent to the acetylene glycol defoaming agent is 1: (0.8-1.2), which can improve the adhesion to level 0 on the basis of a long activation period.

[0032] 5. The film-forming aids include DPM (dipropylene glycol methyl ether) and DPnB (dipropylene glycol butyl ether), and the weight ratio of DPM and DPnB is 1: (1.5-3), which can improve the anti-cracking performance of the paint film on the basis of a long activation period. DETAILED DESCRIPTION

[0033] Examples 1-2, Comparative Examples 1-8

[0034] A varnish with a long activation period, comprising a component A and a component B, wherein the components of the component A, in parts by weight, are as shown in Table 1:

[0035] Table 1

[0036]

[0037]

[0038] The B component is a curing agent (Covestro XP2655), and the weight ratio of the A component to the B component is 3:1.

[0039] The preparation method of the component A comprises the following steps: adding hydroxyl acrylic acid dispersion and hydroxyl acrylic acid emulsion, stirring at a dispersion rate of 400r / min, stirring for 10 minutes, and then adding defoamers in sequence after being evenly mixed, stirring for 4 minutes after each addition, and then adding the next item; then adding the pre-mixed film-forming aid and light stabilizer mixed solution, stirring for 10 minutes, increasing the speed to 600r / min, and adding anti-sagging aid, deionized water and wetting agent in sequence, stirring for 4 minutes after each addition, and then adding the next item. After all are added, stir for 20 minutes to obtain the product.

[0040] Performance Testing Methods

[0041] The coatings prepared in the examples and comparative examples were subjected to performance tests, and the test data are listed in Table 2.

[0042] Bending and cupping: According to the national standard GB / T 9753, bending ≤ 2mm and cupping ≥ 4mm are qualified, otherwise they are unqualified.

[0043] Hardness: According to the national standard GB / T 6739-2006, use a pencil that meets the standard to conduct hardness test.

[0044] Activation period: fully mix the product with the curing agent, add deionized water to adjust the viscosity to the appropriate construction viscosity (according to the national standard GB / T1723, using a convex four-cup measurement, generally 40-50s), test the viscosity change every 1 hour, and the viscosity should always remain in the viscosity range suitable for construction (viscosity ≤ 60s) for at least 4 hours.

[0045] Gloss: The minimum gloss at an angle of 20°. 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 an angle of 20°. ≥80 is qualified, otherwise it is unqualified.

[0046] Adhesion: According to the national standard GB / T 9286, the cross-cut adhesion test is carried out according to the standard.

[0047] Weather resistance: According to the national standard GB / T 14522-2008, the test is passed if the gloss loss rate is ≤15% and the color difference change is ≤3% after 1000h of testing, otherwise it is unqualified.

[0048] Performance test data

[0049] Table 2

[0050] Glossiness Curvature and cupping Adhesion Active Period hardness Weathering Example 1 qualified qualified Level 0 ≥4H H qualified Example 2 qualified qualified Level 0 ≥4H H qualified Comparative Example 1 Failure qualified Level 0 ≥4H HB Failure Comparative Example 2 Failure qualified Level 0 ≥4H HB Failure Comparative Example 3 Failure qualified Level 0 ≥4H HB qualified Comparative Example 4 qualified qualified Level 0 ≥4H F qualified Comparative Example 5 qualified qualified Level 0 ≥4H F qualified Comparative Example 6 qualified qualified Level 0 ≥4H F Failure Comparative Example 7 qualified qualified Level 0 ≥4H H Failure Comparative Example 8 qualified qualified Level 0 ≥4H H Failure

Claims

1. A varnish with a long pot life, characterized in that The invention comprises component A and component B. The component A comprises, by weight, 25-50 parts of hydroxyl acrylic dispersion, 25-45 parts of hydroxyl acrylic emulsion, 10-20 parts of film-forming aid and 5-15 parts of deionized water. The component B comprises a curing agent.

2. The varnish with a long pot life according to claim 1, characterized in that: The weight ratio of the hydroxylated acrylic dispersion to the hydroxylated acrylic emulsion is 1:(0.5-1.2).

3. The varnish with a long pot life according to claim 2, characterized in that: The weight ratio of the hydroxylated acrylic dispersion to the hydroxylated acrylic emulsion is 1:(0.9-1.2).

4. The varnish with a long pot life according to claim 3, characterized in that: The hydroxy acrylic emulsion includes an anionic emulsion with a pH of 6-8.

5. The varnish with a long pot life according to claim 4, characterized in that: The hydroxyl content of the hydroxy acrylic emulsion is 1-3 wt %, and the hydroxyl content of the hydroxy acrylic dispersion is 2-6 wt %.

6. The varnish with a long pot life according to claim 5, characterized in that: The viscosity of the hydroxylated acrylic dispersion at 25° C. is 500-4500 mPa·s.

7. The varnish with a long pot life according to claim 6, characterized in that: The varnish composition also includes light stabilizers, defoamers, anti-sagging aids and wetting agents.

8. The varnish with a long pot life according to claim 7, characterized in that: The defoaming agent includes a polymer defoaming agent and an acetylene glycol defoaming agent.

9. The varnish with a long pot life according to claim 3 or 8, characterized in that The content of the film-forming aid in component A is 10-20 wt%.

10. Use of a varnish with a long pot life according to any one of claims 1 to 8, characterized in that: Used in rail transportation.

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