1. Overview
Emulsions are traditional water-based adhesives used in architectural coatings, particularly compliant with environmental requirements. Generally, outdoor latex paints use pure acrylic, styrene-acrylic, and silicone-acrylic emulsions, and later, tertiary vinyl acetate and tertiary acrylic emulsions were developed.
With the improved performance of vinyl acetate emulsion, the coatings industry has become increasingly familiar with Vinyl Neodecanoate. Its main use is in copolymerizing with vinyl acetate to form emulsions for latex paint formulation. This type of latex paint is relatively rare in my country, but it is extremely common in Europe, where tertiary vinyl acetate emulsions are one of the mainstream products, accounting for over 30% of the entire Western European emulsion market.
Because neodecanoic acid has three branches on its α-carbon and a total of nine carbon atoms, it exhibits significant steric hindrance, making it difficult to hydrolyze and also providing shielding for adjacent groups, greatly improving its overall hydrolysis resistance. It is estimated that one tertiary carbon group can protect 2-3 vinyl acetate linkages.
Vinyl tert-carbonate has various monomers ranging from neopentylene to neotridecylene, each with a different glass transition temperature. Polymers with different glass transition temperatures can be obtained by adjusting their composition in the polymer, thus facilitating different applications.
When vinyl tert-carbonate and vinyl acetate are copolymerized, their reactivity ratio is close to 1. Therefore, they easily form random homopolymers. This allows the esterified vinyl ester to not only effectively protect the adjacent acetate moiety but also extend the polymer chain distribution in a relatively uniform manner, maximizing its effect.
2. Main Application Areas
2.1 Outdoor Paints (i.e., Water-based Exterior Wall Paints) – Vinyl Acrylic/Veneric Emulsions
Generally, latex paints are formulated using pure acrylic emulsions. Sometimes styrene-acrylic emulsions are used; however, latex paints formulated with styrene-acrylic emulsions have poor resistance to yellowing and chalking, and their use is generally not recommended. Silicone-acrylic emulsions can be used when higher quality requirements are needed.
Vinyl acetate is inexpensive, but vinyl acetate emulsions (vinyl acetate emulsions) have poor weather resistance, alkali resistance, and even water resistance, making them unsuitable for outdoor use and not recommended even for high-end interior decoration. Even vinyl acetate-acrylic emulsions with added acrylic copolymers still fail to meet outdoor decoration requirements. However, vinyl acetate emulsions modified with neodecanoate for exterior walls can achieve performance levels comparable to pure acrylic, and even surpass pure acrylic emulsions in alkali resistance and weather resistance.
Due to the steric hindrance effect of the alkyl groups on the α-carbon atoms in neodecanoate, the ester groups on the polymer side chains are difficult to hydrolyze, significantly improving the alkali resistance of the paint film. Results from two years of exposure of a 40% pigment volume concentration colloidal stabilized white latex paint to cement board (alkaline substrate) showed that a tertiary vinyl acetate emulsion containing 15% tertiary vinyl carbonate could improve the alkali resistance of the latex paint to an excellent level.
The shielding effect of the α-carbon atom on vinyl decanoate determines the antioxidant and UV resistance of vinyl decanoate copolymer emulsions, making them suitable as durable and color-retaining exterior architectural latex paints. Existing data shows that a 12-year exposure test confirms that a 25% vinyl decanoate content already exhibits good performance, while a 30% vinyl decanoate content surpasses that of pure acrylic emulsions.
This description indicates that the addition of vinyl decanoate transforms vinyl acetate emulsions, which previously had mediocre outdoor performance, into the performance of pure acrylic emulsions, acting as a catalyst for improvement. Although the cost is slightly higher than that of vinyl acetate emulsions due to the small amount of vinyl decanoate added, it is far lower than that of high-performance pure acrylic emulsions.
Vinyl decanoate and vinyl acetate have similar polymerization rates, making them particularly suitable for random copolymerization. The production process is simple, easy to control, and significantly reduces manufacturing costs.
2.2 High-Performance Wood Protective Coatings (i.e., Water-Based Wood Coatings) – Modified Vinyl Decanoate/Acrylic Emulsion
Due to changing environmental conditions, especially outdoors, wood materials require protective coatings to resist climate damage. These coatings must achieve waterproofing, water vapor permeability, flexibility, wet adhesion, and anti-blocking properties. Vinyl decanter-modified acrylic emulsions can meet these stringent requirements.
In comparisons of clear varnishes and paints modified with vinyl decanter/acrylic emulsions with acrylic emulsions and acrylic clear varnishes, the former consistently outperformed the latter in anti-aging performance, even with the addition of UV absorbers, resulting in a more refined appearance. An 8-week aging test of the clear varnish showed that only the vinyl decanter-modified acrylic emulsion yielded satisfactory results. In a 21-week aging test of white gloss varnishes, the gloss retention performance was significantly stronger than that of acrylic acid and alkyd varnishes.
2.3 Water-based Waterproofing Coatings – Acrylic Emulsion
Most building materials are porous, such as concrete, brick, natural stone, and wood. When used outdoors, they absorb water under continuous wind and rain. When the substrate is severely damaged, the effectiveness of the coating cannot be guaranteed. This places more special demands on coatings. Vinyl decanoate/acrylic emulsion can achieve waterproofing while allowing the moisture contained in the substrate to be released as water vapor, exhibiting water vapor permeability. Most substrates are alkaline materials, and as is well known, alkaline conditions have a strong catalytic effect on hydrolysis; the stronger the alkalinity, the stronger the catalytic effect. As moisture migrates, alkaline substances are carried to the surface, posing a serious threat of alkaline hydrolysis to the tightly contacted coating film, especially to the ester bonds that hold acrylic resin together; alkaline erosion is its greatest enemy. Vinyl decanoate has a large number of alkyl branched groups, which not only protect its own ester bonds but also protect adjacent ester bonds, preventing them from being eroded by alkaline alkali. The experimental results regarding the contribution of vinyl tert-carbonate to the waterproofing and weather resistance of coatings are very encouraging. For example, the waterproofing results measured by the “immersion test” show that the water absorption rate of bricks coated with vinyl tert-carbonate/acrylic emulsion is only 2% of that of uncoated bricks, making it the best water-based system tested, approaching that of commercial aluminum stearate and silicone systems containing solvents.
Based on the analysis of data from the esterification of 24 branched and linear acids, the “six-position rule” was summarized. This rule states that “in the nucleophilic reaction of fatty acids, the more atoms at the 6-position, the greater the steric hindrance.” Vinyl decanoate uniquely possesses a large number of “6-position atoms,” making its hydrolysis resistance 100 times that of vinyl acetate.
The non-colloidal protective vinyl decanoate/acrylic system has a small particle size, allowing it to effectively penetrate into the crevices of porous substrates.
In conclusion, the vinyl decanoate/acrylic system provides comprehensive protection for substrates against corrosion, making it a reliable choice.
2.4 General-Purpose Emulsions for Interior Wall Paints
2.4.1 Tertiary Carbon Emulsions for Zero-VOC Latex Paints
Currently, with increasing environmental awareness, the demand for low-odor and odorless interior latex paints with zero VOC release is growing, placing higher demands on emulsions as paint bases.
The monomer conversion rate is very high during the preparation of neodecanoate/vinyl acetate emulsions, thus minimizing the amount of residual monomers in the emulsion, which is also a source of VOCs. To obtain emulsions with very low MFFT, butyl acrylate can be appropriately added to the formulation; of course, the surfactants and additives used must be environmentally friendly.
Neodecanoate has a 10-carbon branched alkyl structure, indicating strong internal plasticizing properties. Even with a small amount of external plasticizer, it can still form a good film. Therefore, the neodecanoate/vinyl acetate system is a good solution for preparing a new generation of solvent-free interior wall coatings.
2.4.2 Tertiary Carbon Emulsions for Economical Latex Paints
Inexpensive latex paints on the market often come at the expense of their environmental friendliness. To ensure coating performance, such as scrub resistance, leveling, storage stability, and workability, a large amount of inexpensive organic solvents needs to be added to minimize the amount of emulsion used as a binder. Colloidal protective vinyldecanoate/vinyl acetate emulsions possess excellent overall performance, exhibiting both high pigment binding capacity and good stability and flowability, while also being highly compatible with other coating formulations. Therefore, vinyldecanoate/vinyl acetate can be used to prepare latex paints with up to 80% PVC (pigment volume concentration). This allows for the use of a higher-quality, lower-volume binder, reducing the amount of titanium dioxide used, which significantly saves on coating costs. Tests have proven that latex paints formulated with this method meet all performance standards.
2.4.3 Tertiary Carbon Emulsions for Satin Interior Wall Coatings
Vinyldecanoate/vinyl acetate emulsions are more advantageous for high-end interior wall coatings. Satin coatings have a high emulsion content and a high titanium dioxide content, resulting in relatively high raw material costs. Neodecanoic acid vinyl emulsions possess excellent thickening properties, allowing for a reduction in additive dosage while maintaining good rheological properties.
Since indoor applications do not require high alkali and water resistance, the amount of neodecanoic acid vinyl emulsion in the emulsion formulation can be reduced to approximately 20-25%.
Because satin coatings have low PVC content, their mechanical properties are not a concern; the focus should be on the balance between anti-blocking, gloss, anti-sagging, and leveling properties. In our performance tests, neodecanoic acid vinyl emulsions demonstrated superior anti-blocking properties compared to pure acrylic, comparable gloss, and better anti-sagging and leveling properties.
2.5 Tertiary Carbon Emulsions for Non-Polar Substrates Coatings and Adhesives (Improving Product Adhesion)
Due to the low surface tension of plastics, coating is very difficult. Polypropylene, in particular, often requires further treatment to achieve good adhesion. Branched vinyl decanoate is an ideal non-polar structural unit for producing this type of coating, providing a polar gradient between the non-polar substrate and the polar coating. Therefore, vinyl decanoate-rich vinyl decanoate/acrylic emulsions exhibit excellent adhesion.
2.6 Waterborne Fluorocarbon Coatings (using vinyl nonanoate)
As a high-weather-resistant coating that also meets environmental requirements, the research and development of waterborne fluorocarbon coatings is gradually replacing solvent-based fluoropolymer coatings, becoming a key area of coating research in developed countries. Waterborne coatings can be classified into water-soluble, water-emulsion, and dispersion types, with water-emulsion types accounting for 50% of the total and representing a key focus for future coating development. Currently, many products have been launched in the United States, Japan, and Europe, and patents have been applied for. Numerous patent documents indicate that tertiary vinyl carbonate is a suitable monomer for synthesizing waterborne fluorocarbon coatings.
An important system is the trifluorochloroethylene/vinyl nonanoate copolymer system (referred to as the tertiary/fluorine system), preferably a core-shell copolymer. For example, in the water-dispersed core/shell fluoropolymer synthesized by Sawada, the core layer is a copolymer of trifluorochloroethylene-acrylic acid-vinyl neononanoate (Tg > 68℃), and the shell layer is a copolymer of trifluoroethylene, acrylic acid, and vinyl hexanoate (Tg 11℃), with a core/shell ratio of 10/1. The film formed by this dispersion also exhibits good stain resistance, water resistance, and weather resistance.
Domestic reports of fluorinated coatings are produced by polymerizing trifluorochloroethylene, fatty acid vinyl esters, aliphatic enols, and aliphatic olefinic acids. In waterborne fluoropolymer coatings, vinyl acetate is commonly used as a hydrophilic monomer. However, its random copolymerization with trifluorochloroethylene inevitably reduces the performance of the fluororesin due to the polymerization between vinyl esters. Furthermore, due to steric hindrance, the polymerization of CTFE (trifluorochloroethylene)-vinyl neononanoate is more favorable than that of vinyl neodecanoate-vinyl neodecanoate, thus the resin tends to use alternating polymerization of vinyl acetate. One of the main reasons why solvent-based CTFE/VAc fluorocarbon resins perform worse than CTFE/EVE (ethylene ether) fluorocarbon resins is that the former’s alternating polymerization is less stringent.
Vinyl neononanoate, as a hydrophilic monomer in fluorocarbon resin polymers, as mentioned earlier, has hydrolytic stability more than 100 times higher than commonly used vinyl acetate and protects adjacent chain segments. Therefore, its negative impact on the performance of fluorocarbon coatings is much smaller than that of vinyl acetate monomers.
The glass transition temperature (Tg) of the core layer should not be lower than 40°C; otherwise, stain resistance will decrease, and the coating will soften and become clay-like in hot weather. The Tg of the shell layer is -10°C to 30°C. If the Tg is higher than 30°C, film-forming properties will be impaired; if the Tg is lower than -10°C, stain resistance will decrease. Appropriate selection of monomer types and ratios is crucial to ensure the polymer Tg remains within these ranges.
