Functional additive for water-based paints and method of use thereof

Abstract

The present application relates to the field of chemical industry, and more particularly to a functional additive for improving film-forming performance of water-based paint, which comprises: epoxy silane oligomer, modified oligomer vinyl alcohol, polythiol, tertiary amine catalyst and water; the epoxy silane oligomer is generated by the reaction of organosilane with methoxyl and epoxy under the action of ion exchange resin; the modified oligomer vinyl alcohol is generated by the modification reaction of HDI on oligomer vinyl alcohol; the present application also includes the use method of the functional additive: the functional additive is added into the water-based paint, and the addition amount of the functional additive is about 0.5%-3% of the water-based paint sample to be mixed; meanwhile, ammonia is added into the water-based paint; the present application can effectively improve the curing speed of water-based paint in humid environment, prevent blistering and wrinkling, and is suitable for various water-based paint products and easy to popularize.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a functional additive for water-based paints. Background Technology

[0002] Water-based paints are prone to severe bubbling and wrinkling when applied directly in high humidity environments.

[0003] Existing technology US11952506B2 discloses a solution that exhibits water resistance after a period of time following application to a substrate. The synthetic epoxy silane oligomer composition can effectively solve the blistering problem caused by subsequent exposure to water. However, this solution is applicable to a limited number of water-based paints and application scenarios. Furthermore, its effectiveness is limited to specific acrylic polymers or requires specialized synthesis, resulting in narrow application and hindering widespread adoption. Additionally, this patent requires at least one day of drying time. If applied directly to the substrate surface and placed in an environment with humidity exceeding 70%, the paint surface may become damp, resulting in unevenness or even complete failure to form a film. Therefore, it cannot be used in high-humidity outdoor environments. Summary of the Invention

[0004] To address the aforementioned technical problems in the existing technology, this invention proposes a functional additive, specifically as follows: a functional additive for water-based paint, comprising: epoxy silane oligomers, modified low-polyvinyl alcohol, polythiols, tertiary amine catalysts, and water; wherein the epoxy silane oligomers are generated by reacting organosilanes possessing methoxy and epoxy groups under the action of an ion exchange resin; and the modified low-polyvinyl alcohol is generated by modifying low-polyvinyl alcohol with 1,6-hexamethylene diisocyanate (HDI).

[0005] Preferably, the weight-average molecular weight of the epoxysilane oligomer is between 1,000 and 5,000.

[0006] Preferably, the modified low polyvinyl alcohol has a weight-average molecular weight of 5,000 to 12,000.

[0007] Particularly preferred is that the specific component ratio of the functional additive is 2-3 parts of epoxy silane oligomer, 1-1.5 parts of modified low polyvinyl alcohol, 1-2 parts of polythiol, 0.2 parts of tertiary amine catalyst, and 4-5 parts of water.

[0008] Particularly preferred is an epoxy silane oligomer: modified polyvinyl alcohol: polythiol ratio of 2:1:1. This ratio allows for more complete cross-linking reactions between the epoxy groups and the hydroxyl groups of the modified polyvinyl alcohol, and between the epoxy groups and the mercapto groups of the polythiol.

[0009] Preferably, the organosilane containing methoxy and epoxy groups is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0010] The present invention also proposes a method for using functional additives: the functional additives are added to water-based paints, and the amount of functional additives added is 0.5%-3% of the mass of the water-based paint sample to be mixed; at the same time, ammonia water is added to the water-based paints.

[0011] Preferably, ammonia water is used to adjust the pH of the water-based paint system to 9.5-10.

[0012] Preferably, the water-based paint is any one of polypropylene resin water-based paint, polyurethane resin water-based paint, or polyester resin water-based paint.

[0013] Preferably, the humidity of the application environment for the water-based paint is between 60% and 95%.

[0014] Beneficial effects

[0015] This invention utilizes HDI-modified low-polyvinyl alcohol (PVC), where the hydroxyl groups are present. These are mixed with epoxy silane oligomers and polythiols, and ammonia provides the alkaline environment, allowing epoxy curing to occur at room temperature under the catalysis of a tertiary amine. Crosslinking occurs between the epoxy groups and the hydroxyl groups of the modified PVC, and between the epoxy groups and the thiol groups of the polythiols. When mixed in a specific ratio, a complex polymer is formed during rapid curing. As the ammonia evaporates or reacts with carbon dioxide in the air during the reaction, the alkaline environment weakens, and the drying reaction is completed.

[0016] Therefore, the functional additive of this invention has the following advantages: First, this functional additive can significantly improve the curing speed of water-based paints in humid environments, exhibiting good water resistance and anti-water properties even in the initial curing stage. Second, the curing system of the functional additive uses oligomers, resulting in low surface tension of the paint film in the early stages of the reaction, allowing for rapid leveling and film formation with good toughness, thus improving the surface wrinkling and blistering problems of water-based paints applied in humid outdoor environments. Third, this functional additive can be mixed in a low proportion with various commercially available water-based paints while maintaining good technical performance, playing a significant role in high-humidity outdoor environments and being easy to promote. Attached Figure Description

[0017] Figure 1 Film formation effect of blank control (comparative examples 1-5) at 40%, 60%, 80%, and 95% air humidity for five days.

[0018] Figure 2 Example 1-1: Film formation effect at 40%, 60%, 80%, and 95% air humidity for five days. Detailed Implementation

[0019] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0020] Preparation Example 1: Preparation of epoxysilane oligomers

[0021] 50 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (purchased from Maclean's® Reagent, CAS: 2530-83-8) and 18 parts of ion exchange resin (purchased from Sigma-Aldrich®, CAS: 2393-92-2) were added to a reaction vessel. The mixture was heated to 75°C under constant temperature and pressure, and water was added with stirring. The mixture was heated and stirred for 2 hours. After the reaction was complete, methanol was removed under reduced pressure, and the mixture was cooled to room temperature. The ion exchange resin was filtered to obtain approximately 40 parts of product. The product was a mixture of various oligomers. Although it contained a small amount of polymers, the weight-average molecular weight of the epoxysilane oligomer composition was approximately 1600 as determined by GPC.

[0022] Preparation Example 2: Preparation of Modified Low-Polyvinyl Alcohol

[0023] Three parts of low molecular weight polyvinyl alcohol (molecular weight 5000-10000, purchased from Thermo Scientific®, CAS: 9002-89-5) were added to 36 parts of water. The mixture was heated to 80°C with stirring and kept at this temperature for about 1 hour until it was completely dissolved to obtain a polyvinyl alcohol solution. 1,6-hexamethylene diisocyanate (HDI, purchased from Sigma-Aldrich®, CAS: 822-06-0) was added dropwise under high-speed stirring and a constant temperature of 45°C. The reaction was continued for 3 hours to obtain modified low molecular weight polyvinyl alcohol. The weight-average molecular weight was measured to be approximately 8000.

[0024] Preparation Example 3: Preparation of Functional Additives

[0025] The product compositions of Preparation Examples 1 and 2, 1,6-hexanedithiol, and 2,4,6-tris(dimethylaminomethyl)phenol were dissolved in water heated to approximately 60°C according to the following combined proportions. 1,6-Hexanedithiol was purchased from Sigma-Aldrich® (CAS No. 1191-43-1); DMP-30 was purchased from Sigma-Aldrich® (CAS No. 90-72-2).

[0026]

[0027] Example

[0028] The following table outlines the implementation examples.

[0029] Example 12g of the functional additives prepared in the different preparation examples above were added to 100g of acrylic resin waterborne paint, and the pH was adjusted to 10 to obtain the waterborne paint mixture to be tested for performance. Comparative Examples 1-5 are blank controls of waterborne paint without any added functional additives and ammonia.

[0030] Among them, the commercially available acrylic water-based paint was purchased from Carpoly® gray water-based fluorocarbon metallic paint; the ammonia water was a commercially available 2% ammonia solution that meets national standards.

[0031]

[0032] Example 2 : The functional additives of Preparation Example 3-1 above were added to the acrylic resin waterborne paint in different proportions to prepare 100g, and the pH was adjusted to 10 to obtain the waterborne paint mixture to be tested for performance.

[0033]

[0034] Example 3 : Add 2g of the functional additive from Preparation Example 3-1 above to prepare 100g of acrylic resin water-based paint, and adjust its pH to 7, 8, 9, 10, and 11 to obtain a water-based paint mixture to be tested for performance.

[0035]

[0036] Example 4 2g of the functional additive from Preparation Example 3-1 was added to a water-based polyurethane, polyester, and acrylic resin paint to prepare 100g of the mixture. The pH was adjusted to 10 to obtain the water-based paint mixture to be tested for performance. The commercially available polyurethane resin water-based paint was purchased from Nippon® Water-based Polyurethane Matte White Exterior Wall Paint; the commercially available polyester resin water-based paint was purchased from Jiaboyuan® White Water-based Polyester Matte Clear Topcoat.

[0037]

[0038] Performance testing

[0039] The above-described embodiments and comparative examples were applied to substrates, and the surface curing speed (V) of each paint layer was tested under 40%, 60%, 80%, and 95% humidity conditions. 干燥 ).

[0040] Simultaneously, blistering was observed after 5 days of exposure to different humid environments. According to GB / T 30789.2-2014, the blistering level of the coating was evaluated based on size and frequency. The images shown in this standard include four bubble sizes (2, 3, 4, 5), each size further includes four quantification levels (density) (2, 3, 4, 5), as shown in Table 1 below. (Denoted as density (S (size)))

[0041]

[0042] Fail *: Film cannot form due to moisture.

[0043] The curing system of the functional additives in this invention uses oligomers, which have low surface tension in the paint film during the initial stage of the reaction, enabling rapid film formation and exhibiting good toughness.

[0044] Compared to Comparative Examples 1-1 to 1-5, which exhibited severe defects and failed to form films under high humidity conditions (see Appendix) Figure 1 Examples 1-1 and 1-2 showed better effects (see appendix). Figure 2 Its optimal application environment is below 80% humidity, but it can form a film even in a 95% humidity environment and the final film surface defects are significantly less than other comparative examples. This effect is sufficient to cover most outdoor humid environments that are not directly exposed to rain.

[0045] Examples 1-3 contained fewer active ingredients and had a low ratio of hydroxyl:thiol:epoxy groups, resulting in unstable curing and difficulty in film formation under high humidity. However, Examples 1-4 and Examples 2-5 added more functional additives. Although both could be successfully cured, the film layer had varying degrees of defects under different humidity levels due to the intense cross-linking reaction.

[0046] Experiments have shown that adding 0.5g to 3g of the functional additive in Preparation Example 3-1 yields superior results. Small amounts fail to form a film under high humidity, while excessive amounts result in film formation but significant bubbling. The pH and volatility of ammonia during the reaction process also determine the degree of cross-linking; a pH of 9 to 10 helps the functional additive effectively perform its technical functions. Furthermore, the addition of the functional additive to different types of commercially available water-based paints improves their rapid curing and film-forming effects in high-humidity environments, effectively preventing film-forming difficulties and defects caused by humidity.

[0047] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A functional additive for water-based paint, characterized in that, include: The mixture comprises epoxy silane oligomers, modified low-polyvinyl alcohol, polythiols, tertiary amine catalysts, and water; wherein the epoxy silane oligomers are generated by reacting organosilanes with methoxy and epoxy groups under the action of ion exchange resins; wherein the modified low-polyvinyl alcohol is generated by modifying low-polyvinyl alcohol with 1,6-hexamethylene diisocyanate (HDI).

2. The functional additive for water-based paint as described in claim 1, characterized in that, The weight-average molecular weight of the epoxy silane oligomer is between 1,000 and 5,000.

3. The functional additive for water-based paint as described in claim 2, characterized in that, The modified low-polyvinyl alcohol has a weight-average molecular weight of 5,000 to 12,000.

4. The functional additive for water-based paint as described in claim 3, characterized in that, The specific component ratio of the functional additives is as follows: 2-3 parts epoxy silane oligomer, 1-1.5 parts modified low polyvinyl alcohol, 1-2 parts polythiols, 0.2 parts tertiary amine catalyst, and 4-5 parts water.

5. The functional additive for water-based paint as described in claim 4, characterized in that, Epoxysilane oligomer: modified low polyvinyl alcohol: polythiol = 2:1:

1.

6. The functional additive for water-based paint as described in claim 1, characterized in that, The organosilane containing methoxy and epoxy groups is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

7. A method of using the functional additive according to claim 1, characterized in that, Functional additives are added to the water-based paint, and the amount of functional additives added is 0.5%-3% of the mass of the water-based paint sample to be mixed; at the same time, ammonia water is added to the water-based paint.

8. The method of using a functional additive as described in claim 7, characterized in that, Ammonia water is used to adjust the pH of the water-based paint system to 9.5-10.

9. The method of using a functional additive as described in claim 7, characterized in that, The water-based paint is any one of polypropylene resin water-based paint, polyurethane resin water-based paint, or polyester resin water-based paint.

10. The method of using a functional additive as described in claim 7, characterized in that, The humidity of the environment in which the water-based paint is applied is between 60% and 95%.

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