With the strengthening of environmental protection regulations, solvent-based coatings have been restricted, which has led to the development of environmentally friendly coatings such as high-solids coatings and water-based coatings. In particular, water-based coatings using water as a solvent have the advantages of saving resources and low VOC emissions. And get rapid development.
The waterborne epoxy acrylic dip coating developed in this paper not only retains the advantages of solvent-based coatings, but also simplifies the coating of complex-shaped workpieces. It is mainly used for the coating of automobile chassis. After more than three years of use, the dip coating can fully meet the performance requirements.
Acrylic acid, butyl acrylate, methyl methacrylate, hydroxypropyl acrylate, styrene, epoxy resin, dimethylethanolamine, butanol, benzoyl peroxide, glycol ether solvents are all industrial grade.
Add butanol and epoxy resin to a four-necked flask equipped with a stirrer, thermometer, and reflux condenser, and raise the temperature to 110°C. Add the mixed monomer dissolved with benzoyl peroxide dropwise at a constant speed within 1.5 to 2 hours After the dripping is completed, keep warm until the conversion rate is greater than 98%, add glycol ether solvents, then add dimethylethanolamine for neutralization, to the resulting epoxy acrylic resin pH value 7 ~ 7.5, and use a certain amount Dilute the water and dilute it to 50% 2% solid content. Discharge the material to prepare a light yellow transparent viscous waterborne epoxy acrylic resin.
Production process: Put a part of water-based cyclic acrylic resin, special diluent and all dispersant into the paint mixing tank, mix evenly, add various pigments and fillers, and evenly disperse, use a sand mill to grind to 30m detail to make up the remaining Water-based epoxy acrylic resin, defoamer, water-based amino resin, thinner, stir evenly, filter, and package.
The key to epoxy acrylic resin formulation is to select monomers, and to meet the technical requirements of paint film characteristics through the combination of different monomers. The glass transition temperature (Tg) of the copolymer is very important. When the copolymer undergoes a glass transition, many physical properties, especially mechanical properties, change dramatically. Calculate the Tg of the copolymer according to the formula, adjust the hardness of the resin, and introduce hydroxyl and carboxyl groups to achieve water-soluble and cross-linked functional groups. The physical properties and main functions of the monomers used are shown in Table 3.
Choose resins with different ratios of the above monomers. As the Tg of the copolymer decreases, the flexibility of the paint film is good and the foaming tendency is reduced.
One of the methods for preparing the water-soluble resin used is to use organic amines to neutralize the carboxyl group on the epoxy acrylic resin to form a salt, thereby obtaining water solubility. Organic amines are volatile. When the coating is heated to form a film, COOH is released due to the volatilization of the organic amine and reacts with the amino resin in the coating to form a cross-linked coating film with excellent performance. The choice of amine affects the viscosity, storage stability, and curing of the coating and its performance. Baking foaming and surface wrinkling of water-based paint film, amine is one of the influencing factors. Triethylamine has strong alkalinity, and the reaction proceeds in the direction of salt formation. Its dosage is small and its boiling point is low. As soon as it reaches the surface, it evaporates and forms a film. The surface of the coating film is dry, but the interior has not yet dried out, causing surface defects. And dimethylethanolamine is just the opposite, so this experiment uses dimethylethanolamine as the neutralizer.
In order to improve the water solubility of the resin, adjust the viscosity of the material and the leveling of the coating film, a small amount of hydrophilic co-solvent must be added, such as low-grade alcohol and alcohol ether solvents. In this formula, glycol ethers and butanol are used as co-solvents, mixed with water in a certain proportion, and the resulting coating has high construction solids, moderate viscosity, and good appearance and leveling. Glycol ether solvents are harmful to humans and can be replaced with propylene glycol ether solvents.
Choose water-based amino resin and epoxy acrylic resin to form a film, making it into a non-melting and insoluble coating film. The amount of amino resin has an effect on the physical properties of the coating film, such as impact resistance, flexibility, hardness, adhesion, etc. The effect of different amounts of amino resin on the properties of the coating film is shown in Table 4.
Epoxy acrylic resin/amino resin Hardness Impact resistance/cm Flexibility/mm Adhesion/level
As can be seen from Table 4, when the ratio of epoxy acrylic resin to amino resin is 6-8:1, the overall performance of the coating film is better.
Water-based paints use water as a solvent, and most resins are weakly alkaline, so the pigments used in water-based paints are different from those used in solvent-based paints. Waterborne coatings require that the pigments can withstand high temperatures, that the pigments do not swell in water, that the pigment paste does not return to coarseness with water, and that the pH of the pigments is close to neutral. If the pH value is too high, it will easily cause saponification of the resin; if the pH value is too low, it will be acidic, which will cause the resin to flocculate and stratify. The pigments and fillers used in this experiment meet this requirement.
Since the launch of De Aiwei's oil-free paint in 1936 laid the beginning of modern latex paint technology, German De Aiwei has been at the forefront of the water-based paint industry. In the development process of nearly one hundred years, Tecway always treats production with a professional attitude..[detailed]
Recently, the Oxyide brand health-type negative oxygen ion water-based paint product developed by Qingdao Hengxi Technology Co., Ltd. has won the recognition of many franchisees and direct users for its unique and excellent air health improvement capabilities. [detailed]
Enterprises need to be big, brands to be strong, and what do they rely on? "To be professional, to be refined, and to be strong, to be strong" is the belief that all employees of D&A always adhere to. The careful selection of coating raw materials is the consistent adherence of De Aiwei to the "specialist". [detailed]
On August 17th, sponsored by China Waterborne Coatings Industry Strategic Alliance and hosted by Chenyang Water Paint, Blue Advocate Home Improvement Safety Day and the "Green Nest" Alliance Summit Forum, and the signing ceremony of the Top 100 Decorations of Huanxiong'an Economic Belt in Xiong'an. .[detailed]
Solid products are the foundation of the company, and environmental protection functional coatings-De Aiwei is well-known in Europe for its strict procurement system, excellent product quality, and excellent service experience. [detailed]
The characteristic of water-based coatings is that water is used as a diluent instead of solvents, which fundamentally reduces the solvent content of the coatings, which can avoid the fire hazards caused by the volatilization of solvents during production and construction, and the health hazards of solvents to the human body, which can be reduced. .[detailed]
Recently, the China Waterborne Coatings Innovation and Development Forum was held at the Midday International Hotel. The theme of the forum was "Focus on Industry Consensus and Cooperation, Join Forces and Green Development for the Future". The participating companies have expressed that China's waterborne coatings industry strategic alliance is water paint. .[detailed]
On June 22nd, China Waterborne Coatings Innovation and Development (Xiongan) Forum was grandly held in Dawu International Hotel, Baoding, Hebei. This event was jointly organized by Chenyang Water Paint and Longman Baililian Group. More than 200 paints and upstream and downstream enterprises participated..[detailed]
Pan Ji's new material "three coating and two baking"/"three coating and one baking" is a brand-new coating process. The 3C2B/3C1B coating process that can save energy and reduce the primer drying process and the application of water-based environmentally friendly coatings have become the trend of industrial coating development. [detailed]