Analytical wood door coating core: coating selection and coating process

Nowadays, wooden door factories all over the country have sprung up. Many wooden door enterprises claim to have an annual output of more than 100,000 sets of solid wood doors. This scale has only been seen in Hong Kong-funded enterprises in the Pearl River Delta region in the past few years, and the development speed is rapid. However, we should still be soberly aware that there is a huge difference in the development of the localities, regardless of the scale of the enterprise, product quality, production efficiency, cost control, brand building, marketing channels, and management level.

The painting operation of the wooden door is the last production process in the wooden door manufacturing process, and is also a very important process in the wooden door process. The level of painting work can largely reflect the manufacturing level and competitiveness of a wooden door enterprise. The painting operation of the wooden door is also the most technical operation in the whole wooden door manufacturing process. I often hear the sighs of the wooden door factory owners: wood doors, woodwork does not have to bother, it is the most headache.

When it comes to the painting of wooden doors, the core is: wooden door painting application technology and painting management. In this article, the author will focus on the introduction of wood door painting application technology. The application technology of wooden door painting is divided into three parts: the selection of coatings, the design of coating process, and the application of coating equipment.

First, the selection of coatings

The coatings are mainly divided into five types: PU coating (polyurethane lacquer), PE coating (unsaturated resin lacquer), NC coating (nitrocellulose lacquer), UV coating (ultraviolet curing lacquer), and W coating (water lacquer). In the wood door painting, the above five coatings are commonly used. They account for different shares in different categories of enterprises at different times.

1, PU coating

PU coating is one of the most commonly used paint varieties in domestic companies. It has good comprehensive performance, such as: good construction performance, filling, fullness, hardness, grinding, scratch resistance have good performance. PU paint is the most widely used in wood door painting.

2, PE coating

The most commonly used PE coatings are PE primers. It is divided into a clear primer and a colored primer (primarily a white primer). PE primer is a kind of paint with high solid content. It has high hardness, strong anti-sag property and high fullness, but its construction performance is more complicated and brittle. PE topcoats are only bright products and have no matte finish, so the use of PE topcoats on wooden door finishes is rare.

3, NC coating

NC coating is a very old paint and a very widely used variety. Its main applications on wooden doors are: transparent lacquer, colored lacquer (white, beige). Nitrocellulose lacquer has good construction performance and shorter coating time. Transparent nitrocellulose lacquer is commonly used in "open" and "semi-open" painting effects, and has a good expressive power. The solid color lacquer is mostly used in the full-closed coating effect.

Among the Hong Kong-owned wooden door enterprises, when engineering door projects are used, the most common one is to use the solid color base and the solid surface of the nitro solid to carry out the painting work. Of course, it also has limitations, such as insufficient fullness, poor hardness, poor solvent resistance, and unsuitable cooperation with high fullness and high gloss products.

4, UV coating

UV coating is one of the two most environmentally friendly coatings in the world (the other is water-based paint). As a new paint, it has developed rapidly in recent years, especially in the Pearl River Delta region, the Yangtze River Delta region, furniture factories, wooden door factories, wood flooring factories are used very much, this is a very new expansion Coatings; the processes, equipment and technologies associated with this are becoming more and more mature.

The first companies in the wood door factory to use UV coatings are mainly concentrated in Hong Kong-owned enterprises in the Pearl River Delta region.

Originally, transparent UV and UV surfaces were used to make transparent or transparent colored wooden door products. With the common development of UV coating technology and equipment technology, the construction technology of solid color UV products is also mature. At present, many companies in the Pearl River Delta region have used UV coatings to produce solid color wooden doors.

In addition to environmental protection, UV coatings are also excellent in coating performance, with good hardness and chemical resistance. High efficiency and low cost are also key factors for the widespread use of UV coatings. Its efficiency is dozens of times the general coating efficiency, and the cost of the paint used is 1/3-2/3 of the general coating. If you count the labor costs, the cost savings will be even more impressive.

However, UV coating also has its limitations. It can only be applied to the flat door wooden door by roller coating. In addition, UV coating has a relatively large investment in equipment. In the early days, a complete UV coating line was imported from abroad at a price of 15 million yuan. At present, there are many joint ventures and foreign-funded enterprises in China that produce similar equipment production lines, ranging in price from several hundred thousand yuan to several million yuan.

5, W coating

W coating is a water-based coating that is as environmentally friendly as UV coatings. Waterborne coatings are a new breed that is developing rapidly in coatings. In Europe and the United States, most of the home decoration is constructed with water-based paint. There are relatively few applications on furniture and wooden doors, but there are also some companies that use waterborne coatings to meet specific foreign customer requirements.

Water-based paints have relatively low solid content, thin paint film, low hardness, poor water resistance and high cost. However, with the continuous development of coating technology, these limitations are gradually being solved.

The choice of coating type for the wooden door depends on the positioning of each product and the requirements for the surface effect of the product. Reasonable selection can achieve the desired effect and save labor and materials. On the contrary, it pays a high price but can't do what it wants. For example, customers require wooden doors to have a good fullness, and manufacturers use NC coatings for painting operations, which is twice the time and twice the amount of materials can not make too good results. Conversely, if the customer wants a fully open painting effect, then the choice of NC coating is an excellent choice.

Second, the coating process design

1. The basic basis and procedures for its process design are:

According to the customer's requirements and standards for wooden door products, the types of coatings are selected, and the painting process and equipment configuration are determined.

2. Common wooden door product coating requirements and standards

(1) Requirements for environmental protection

If the customer does not have special requirements, it will be executed in accordance with the "GB GB581". There are more stringent environmental requirements, which can be based on the specific parameters provided by the customer.

(2) Requirements for the surface effect of the coating

Overall effect: fully enclosed, semi-open, full open. Specifically, there are: gloss, color, fullness, permeability, hardness, leveling, soft scratch resistance, adhesion, brittleness, and the like.

(3) Chemical resistance requirements for coatings: yellowing resistance, acid and alkali resistance, and remelting resistance

3. Coating products

The selection of coating products is an important part of the coating process. The specific basis for selection is: requirements for effects, requirements for environmental protection, requirements for cost, requirements for efficiency, and requirements for operating habits.

4, painting operation process

The painting process is the most critical part of the wood door painting process design. The design of the coating process is critical to the effects of coating efficiency, coating cost, and coating performance. Sometimes, the same painting effect can be used to design different painting processes, but how to choose the most efficient job design is an important technology, which requires advanced technical accumulation and coating application capabilities.

5, the selection and configuration of painting equipment

When the coating product selection and painting process are designed and finalized, the selection and configuration of the coating equipment will have a fundamental impact on the coating efficiency. With the continuous improvement of labor costs, technical talents are becoming more and more scarce, and the use of automated painting and polishing equipment is particularly important. Especially in the field of wooden door manufacturing, the grinding efficiency of the product is the most important part of the final efficiency of the wooden door manufacturing, and it is also an important embodiment of the manufacturing ability of an enterprise.