Waterborne Silicone Acrylic Resin Coatings for Low Gloss and Scratch Resistance
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Solution Overview
Problem
Conventional 2K waterborne polyurethane coatings struggle to meet simultaneous performance requirements such as low gloss, chemical resistance, adhesion, and scratch resistance, especially at lower dry film thicknesses, and do not perform as well as solvent-borne polyurethane coatings in these aspects.
Innovation Solution
A waterborne polymer system comprising a silicone-modified acrylic emulsion with 1-30% silicone by weight, a hydroxyl functional acrylic monomer, and a secondary binder like acrylic emulsion or polyurethane dispersion, with a hydroxyl equivalent weight of 400 g/mol or less, providing improved adhesion, chemical resistance, and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 2K waterborne polyurethane coatings are used, then the coating can be applied, but it cannot simultaneously achieve low gloss, chemical resistance, adhesion, scratch resistance, and thin film thickness
Solution Approach 1:
The patent uses a composite binder system combining waterborne polyurethane dispersion with silicone-modified acrylic emulsion and polyester polyol. This composite material approach allows the coating to achieve multiple performance requirements simultaneously: adhesion (from polyurethane), chemical resistance (from polyester polyol), and low gloss/matte finish (from silicone modification), while maintaining thin film thickness capability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the binder system by incorporating silicone-modified acrylic emulsion with specific Tg ranges and hydroxyl equivalent weights. By changing the molecular parameters (OH EW of 400 g/mol or less, Tg of -50°C to 20°C) and composition ratios, the coating achieves improved adhesion, chemical resistance, and surface properties while maintaining low gloss and thin film applicability.
2Shape
If the coating achieves lower gloss and thinner film thickness, then the aesthetic requirements are met, but adhesion, chemical resistance, and scratch resistance deteriorate
Solution Approach 1:
The patent applies local quality by using silicone-modified acrylic emulsion specifically to provide low gloss and surface slip properties at the coating surface, while the waterborne polyurethane dispersion and polyester polyol provide adhesion and mechanical strength throughout the film matrix. This localized functional distribution allows low gloss/thin film without sacrificing adhesion or scratch resistance.
Solution Approach 2:
The composite binder system combines materials with complementary properties: waterborne polyurethane for adhesion, polyester polyol for chemical resistance, and silicone-modified acrylic for low gloss/surface slip. This composite approach enables the coating to achieve low gloss and thin film thickness while maintaining or improving adhesion and scratch resistance through synergistic material interactions.
3Object-generated harmful factors
If conventional waterborne polyurethane coatings are used, then the coating can be applied, but chemical resistance, mar resistance, wear resistance, and adhesion do not perform as well as solvent-borne polyurethane coatings
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating water-reducible polyester polyol with specific molecular weight ranges and hydroxyl values, along with silicone-modified acrylic emulsion having controlled Tg and OH EW. These parameter modifications enable the waterborne system to achieve chemical resistance and mar resistance comparable to solvent-borne coatings, while maintaining adhesion and environmental benefits.
Solution Approach 2:
The composite binder system combines waterborne polyurethane dispersion with polyester polyol and silicone-modified acrylic emulsion to create a synergistic formulation. The polyester polyol provides enhanced chemical resistance and crosslinking capability, while the silicone-modified acrylic contributes to surface properties and adhesion. This composite waterborne system achieves performance parity with solvent-borne coatings in chemical and wear resistance.
Data Source
AI summary
The present application relates to a waterborne polymer system suitable for two-component polyurethane coating applications. Provided herein is a waterborne polymer system comprising: 1) a silicone-modified acrylic emulsion comprising: about 1% to about 30% by weight silicone based on resin solids; and at least one hydroxyl functional acrylic monomer; and 2) at least one secondary binder comprising at least one acrylic emulsion, at least one water-reducible polyester polyol, at least one polyurethane dispersion, or combinations thereof; wherein the silicone-modified acrylic emulsion has a Tg of about −50° C. to about 20° C.; and wherein a hydroxyl equivalent weight (OH EW) of the silicone-modified acrylic emulsion is about 400 g solid/mol or less. A waterborne coating is also disclosed comprising the waterborne polymer system described herein. These waterborne polymer system and two-component water-borne coating compositions including the silicone-modified acrylic emulsion are capable of achieving high chemical resistance, strong adhesion, especially after weathering, and excellent scratch and mar resistance at low gloss.