One
Application field of Waterborne Wood Coatings
The main film-forming material of waterborne wood coatings is waterborne resin. The commonly used resin types of wood coatings are mainly classified as acrylic acid, polyurethane, acrylic polyurethane and waterborne alkyd according to chemical structure. Moreover, the film-forming process of waterborne wood coatings is a non-homogeneous and non molecular irreversible process, which has gone through the accumulation, compression and fusion stages of latex particles. In order to form a high quality film, it is often necessary to rely on film forming AIDS, and the compactness is relatively poor. Moreover, the film-forming material of water-based wood coatings has a large hydrophilicity, so the film is relatively poor in water resistance, chemical resistance and other properties compared with solvent based coatings. In order to solve the defects of single component waterborne wood coatings, waterborne two-component wood coatings and Waterborne UV coatings have developed rapidly and been widely used in recent years. The advantages of waterborne wood coatings are simple construction, small smell, good adhesion and good leveling. The disadvantages are relatively slow drying speed, general hardness and chemical resistance. Therefore, the water-based wood coatings can be applied to the wood coatings which do not require high hardness and do not often contact with strong corrosive solvents. The wood products that meet the above characteristics in industrial coating mainly include children's toys, suite furniture, wooden dining chairs, wooden window frames, indoor wooden doors and wooden floors.
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Two
Coating effect and coating process design
There are many kinds of wood products, from the wood grain, deep ducts (such as Fraxinus mandshurica, oak, etc.) and shallow ducts (such as birch, red cherry, etc.); from soft to hard degree, cork (such as Korean pine, phoenix tree, linden wood, etc.) and hardwood (such as elm, rosewood, oak, etc.); from wood products, they are made of density board, density board, leather, solid wood and so on. Pure solid wood, etc. In the industrial application of waterborne wood coatings, it is necessary to select the appropriate coating effect and coating process according to the type of wood materials and the application of the coated wood products.
Wooden children's toys
China is a big toy manufacturer in the world. About 70% of the international toy market sales are provided by China. Wooden children's toys mostly attract consumers with bright colors and imaginative shapes, so the materials need good machinability; most of the commonly used materials are density boards, but also some solid wood products such as beech and pine. The density board is cheap in price and has good machinability, without the texture of natural wood. The most suitable coating effect is solid color paint, which generally adopts the process of two bottoms and one side. In beech and pine, it is generally coated with clear primer, clear finish or transparent color paint to achieve the effect of exposing the natural wood grain of wood. The coating method can be coating, brush coating, roller coating and dip coating. It should be noted that there are many adhesives in the density board, and the raw materials used are relatively messy, so the construction of water-based primer is very important. When coating, it is necessary to select a water-based primer with sealing tannic acid and grease properties to prevent the film from discoloration. Wood children's toys are not required to have high performance in terms of coating film. What needs to be strictly controlled is the content of harmful substances in the coating film, including heavy metals, polycyclic aromatic hydrocarbons, glycol ether and its esters, benzene series, free formaldehyde, etc. The coating smell of toys should be small; in terms of chemical resistance, it only needs to be able to meet certain daily chemicals such as water and alcohol resistance and drinks such as coffee and green tea resistance; wooden children's toys don't need high requirements for coating hardness, but need better flexibility, crack resistance and temperature change resistance; the coating has good adhesion to wood, and the paint can't fall off at the corners of toys; because it is very Most of them are container export products, so they also need to have good high temperature anti backtack performance. In many years of practical application, water-based wood coatings can meet the above performance requirements of children's toys.
Wooden dining chair
From the practical application point of view, the dining chair is mainly used for people to eat and rest indoors. In the process of moving or moving the position, there will be bumps and problems of coffee or tea spilling on it. Therefore, the finished wooden dining chair requires good adhesion to the coating, excellent tea, coffee, red wine and coke stain resistance, and good adhesion resistance. The daily output of wood dining chair manufacturers is large, and the average medium-sized dining chair manufacturers can produce more than 1000 pieces per day, which requires high production efficiency. Therefore, most of the wood dining chair manufacturers use assembly line coating. The assembly line has heating and drying system, so the defect of slow drying of waterborne wood coatings can be made up. The wood used for wooden dining chairs is mostly solid wood such as beech, oak, ash, maple, etc. the painting effect adopted is mainly open and semi open, and can be divided into varnish and solid paint. Varnish can be used for the painting effect of natural color (without any color effect) or transparent color. The transparent color effect is generally colored by the bottom coloring process; the solid color is generally black and white Too many. The typical coating process is as follows: use two bottoms and one or two bottoms and two sides, spray 1-2 guns each time, dry the coating at room temperature for about 10 minutes after spraying each time, enter the baking system for forced drying after the coating surface is dry (the general temperature is controlled at 30-40 ℃) for about 1 hour, come out for cooling for 10 minutes, then polish and dust removal, and then enter the next process. After coating, the coating of wooden dining chair is smooth and delicate, with good transparency of varnish, clear wood grain, natural color, strong covering power of solid color paint and no fading.
Indoor wooden door
The selection and collocation of decorative wooden doors with the most expressive factors in interior decoration is the finishing touch of the whole process of home decoration, and wooden doors are more and more favored by decoration owners. Generally speaking, the indoor wooden door needs to have a small smell, good flexibility and adhesion, good handle, and certain water-resistant wiping performance. Generally, the requirements for solvent resistance are not particularly high, and the hardness is moderate. In factory coating, it is batch production. When spraying, first spray a plane of the door, waiting for about 5-10 Spray another plane after min, and then hang it to dry, so it is required that the coating used should be flat, dry quickly and resistant to flow hanging. There are many kinds of materials for indoor wooden doors, so it is very important to choose the coating process reasonably according to the types of materials in the application of Waterborne Wood Coatings for indoor wooden doors. ① For wood with deep grain, such as Fraxinus mandshurica and oak, the full open coating effect is generally adopted, because the solid content of waterborne wood coatings is relatively low and the fullness is relatively poor. If the fully enclosed coating effect is adopted, the number of spraying times will require twice or more of PU (polyurethane) coating to achieve satisfactory film fullness, and the drying speed of water-based coating itself is much slower than PU coating, so that the production time of a set of doors in the factory will take 7 days or even longer, greatly reducing the production efficiency of the factory. With the open effect, the typical coating process is about two bottoms and one side. Only 2-3 guns are needed for each coating, which greatly shortens the drying speed and improves the production efficiency. ② For the wood with light grain, such as red cherry and maple, the full sealing effect can be adopted. The typical process is about three bottoms and one side, and each time 4-5 guns need to be sprayed. If the material is density board, the full sealing coating effect of solid color can be adopted, because the solid content of solid paint is higher than that of varnish, and the coating process of three bottoms and one side can achieve better coating effect.
Wooden suite furniture
Wooden suite furniture mainly refers to clothes cabinet, bed and bedside cabinet, especially now children's suite furniture, the application of water-based wood paint occupies a large proportion. Suite furniture has been in direct contact with us for the longest time. The size of its odor and the content of harmful substances directly affect our life and health. Although the performance of solvent based coatings is better than that of water-based wood coatings, with people's attention to health, the green and environmentally friendly water-based wood coatings have developed rapidly. In terms of coating performance, suite furniture requires good adhesion, certain water resistance, good impact resistance, fine hand feel and good transparency; in terms of factory coating, the coating used needs to have good leveling, flow resistance and fast drying speed, and the current water-based wood coating can fully meet the above requirements. The material of wooden suite furniture is also as wide as that of indoor wooden doors: deep wood like Fraxinus mandshurica and oak generally adopts the full open painting effect, with the typical process of two bottoms and one side; shallow wood like red cherry and maple can adopt the full closed effect, with the typical process of three bottoms and one side; if the material is density board, it can adopt the full color Closed coating effect.
Wooden floor
With the improvement of people's living standard, the cold tiles used to be used are more and more replaced by wooden floor to decorate the floor or even the wall protection board. Especially the bedroom, study and living room floor, more people like to use wooden floor to lay. The wooden floor feels comfortable, especially suitable for the elderly and children. It is very suitable for the human body, especially for the natural and warm home environment. The most important requirements for the coating performance of the floor are wear resistance and scratch resistance, followed by the resistance to daily chemicals. In terms of properties, it is difficult to meet the requirements of the general one component waterborne wood coatings, especially the water-based acrylic system. The water-based PUD resin has certain advantages in wear resistance, and its wear resistance is even better than that of solvent based PU coating, but it is slightly deficient in fullness and water resistance. Therefore, the water-based wood paint system for wood flooring generally adopts the water-based two-component system or the water-based UV system. The water-based two-component system here refers to the product that reacts with polyisocyanate. The dense coating film is formed by the crosslinking reaction between the water-based resin a containing - oh and the water-based polymer B containing polyisocyanate Cross linked reactive products. This kind of waterborne wood coatings is also a kind of products whose performance is closest to that of solvent based coatings, and its wear resistance is better than that of solvent based Pu; however, the performance ratio of UV curable wood coatings and traditional UV curable coatings can be said to have obvious advantages, the outstanding advantage is that VOC can tend to zero, no active diluent is needed, and the viscosity is easy to adjust, which not only reduces the odor of active diluent and the stimulation to human body The hardness of the coating is slightly lower than that of the traditional UV coating, but the results of abrasion resistance, scratch resistance, chemical resistance and cupping test can be better than that of the traditional UV coating. The disadvantage is that the infrared drying performance needs to be increased for water flash drying before entering the UV machine, but it is only a kind of equipment investment, and other coating lines can also be used, not a waste. From the material point of view, the material types of wooden floor are mainly solid wood (including the veneer on the density board), and the shape is mostly regular rectangular flat plate. Therefore, the factory production of floor is mainly supported by the roller coating production line with infrared drying, and the UV curing water-based wood coating is supplemented by the UV drying. The typical coating process of water-based two-component floor coating is two bottoms and one side, while the UV curing water-based wood coating is mostly three bottoms and one side.
Wooden cabinet
With the rapid development of home decoration industry, the whole cabinet is very popular. The whole cabinet can