Alkyd resin

Alkyd resin: Properties: Alkyd resins are a general term for thermosetting resins that are produced by the esterification and condensation of polyacids, other polyacids, and various other acid units. It is sometimes also called polyester resin. Common polyols include ethylene glycol, glycerol, pentaerythritol, neopentyl glycol, trimethylolpropane, xylitol, sorbitol, and others. Common polyacid compounds include phthalic acid (or anhydride), isophthalic acid, terephthalic acid, succinic acid (or anhydride), trimellitic anhydride, and quinoline dicarboxylic acid, etc. Common monobicarboxylic acids include rosin acid, benzoic acid, synthetic fatty acids, and fatty acids from vegetable oils. Alkyd resins account for 95% of applications in coatings, making them a very important type in the coating industry. It is usually mixed with drying oils as a film-forming agent for coatings. The addition of dry oils improves solubility, increases the strength of the film, and enables cross-linking in air. Commonly used drying oils include natural coconut oil and soybean oil, among others. The acid groups in these oils are long-chain fatty acids containing unsaturated bonds, and when dried in air, the oxygen in the atmosphere causes them to cross-link at those unsaturated bonds. Using a drying agent can speed up this process. Based on the drying rate of unsaturated alkyd resin coatings, these oils are further classified into drying oils, semi-drying oils, and non-drying oils. Depending on the oil used, alkyd resins can be divided into dry and non-dry types. The percentage of oil in alkyd resin is called the oil content. For this reason, alkyd resins are also classified into long-, medium-, and short-oil versions. Long-oil type has an oil content of over 60%, medium-oil type has an oil content between 50% and 60%, and short-oil type has an oil content of over 50%. In addition, there are also ultra-long oil alkyds (with an oil content of over 85%) and ultra-short oil alkyds (with an oil content of under 5%). Increasing the oil content can improve the flexibility of the paint film. In the case of long-chain, medium-oil-content alkyd resins, drying relies primarily on the oil content, which is why drying accelerants are necessary. Low oil content is mainly achieved through solvent evaporation, and it is often used in paint drying. Alkyd resins have good film-forming properties, as well as excellent heat resistance, weather resistance, saltwater resistance, and resistance to aliphatic solvents. Other polymer compounds (such as phenols, amines, silicone styrenes, etc.) are also often added to alkyd resins to modify them and improve their physical properties. Uses: It is mainly used in formulating coatings, such as exterior alkyd resins, general-purpose alkyd resins, primers, anti-rust paints, insulating paints, corrugated paint, and soluble resin paints. It is also used in the production of adhesives, plasticizers, inks, and film plastics.

Amino alkyd resin coatings, such as Amino or AC (Acid-Curing), were quite popular in China during the 1990s, and they used to be the preferred choice for furniture manufacturers for painting their products. With the rapid development of polyurethane paint (PU paint), domestic consumers have gradually come to appreciate its advantages of high fullness and high hardness, causing AC paint to fade away from the market. This year, with the rapid development of the domestic furniture industry and the increase in furniture exports, particularly of cabinet products to countries such as North America and Northern Europe, furniture manufacturers are placing increasing demands for faster coating processes and higher environmental standards. In this context, UV and AC paints have once again come to the forefront. I. Advantages of AC paint 1. The coating dries quickly, making it suitable for use in line painting processes. After application of AC paint, it dries rapidly at ambient temperatures above 20 degrees, with a drying speed similar to that of nitro paint. If drying in a drying room is used, the primer can be sanded after half an hour at around 50 degrees, which is very suitable for production on a rotary conveyor line. If the reel wire is long, after applying the AC topcoat, it can be dried on the line for 40 minutes before being taken off the line for lamination or packaging. 2. The paint film has a high fullness, and is tough and wear-resistant. Nitro paint dries quickly and has a very long activation period, making it particularly suitable for production use. Nitro paints, on the other hand, have the drawbacks of poor film fullness and low film hardness. The drying speed of AC paint is slightly slower than that of NC paint; it is particularly suitable for use in line coating even when baked. Its film thickness and hardness are similar to those of PU paint, but its wear resistance is better than that of PU paint. In terms of the performance achieved by the final product, AC paint yields results that are between those of PU and NC paints; it is particularly suitable for use in assembly-line painting processes, and it offers excellent decorative and protective properties. Nitro paint is a volatile, self-drying paint that provides an excellent decorative finish. However, since its coating swells when exposed to strong solvents, furniture painted with nitro paint should not be wiped down with strong solvents; alcohol or soapy water is the better choice. In addition to possessing the decorative properties of NC paint, AC paint undergoes a cross-linking reaction under the catalysis of acids to form a film, which results in a protective effect of the coating that is significantly better than that of NC paint; its performance is close to that of PU paint. 4. Excellent environmental performance. AC paint uses a large amount of renewable alcohol solvents in its formulation, which helps to protect resources. Moreover, the alcohols obtained through biological fermentation cause less environmental pollution, as most of them are biodegradable. 5. Excellent yellowing resistance. AC white paint exhibits excellent resistance to yellowing; under indoor conditions, the coating shows no significant color variation over several years. Its resistance to yellowing is comparable to that of nitro white paint, and it offers a significantly better cost-performance ratio compared to PU white paint. The yellowing resistance of ordinary AC varnish is comparable to that of PU varnish. II. Precautions for AC paint 1. An unpleasant odor is present during application. The film-forming component of AC paint mainly consists of amino resins; since the residual amount of monomers in these resins varies depending on the manufacturer, an irritating odor is released during the drying process after application. Ventilation in the drying room where the workpieces are dried needs to be improved in order to reduce the concentration of released monomers and thereby lessen the odor. 2. It is only suitable for pipeline painting with a heating device. AC paint dries slowly at low temperatures (below 10 degrees), making it difficult to meet the requirements of assembly line operations. III. Construction methods and equipment for AC paint. AC paint is applied by spraying or dipping. Regardless of the construction method used, a drying room is required to accelerate drying. Generally, the length of the production line ranges from 600 to 1200 meters; only a sufficient length can ensure an appropriate drying time. Therefore, each furniture factory must choose an appropriate length for its production line based on the volume of furniture it produces. The investment required for an AC paint production line generally ranges from 100,000 to 300,000 yuan