Perspective process technology and influencing factors of coating technology (I)

The concept and significance of film

The film is the film, which is the processing technology of the plastic film coated with adhesive, and the paper prints are heated and pressed together to form a paper-plastic product. The laminated film has a thin and transparent plastic film on the surface, and the surface is smoother and brighter, which improves the glossiness and fastness of the printed matter. The graphic and text are more vivid and full of three-dimensional. Waterproof, anti-fouling, wear-resisting, folding-resistance, chemical resistance, etc.

The protective effect of the film is undeniable. Whether it is wear-proof, waterproof or UV-resistant, their functions are incomparable with ink and paper. Especially for those works that need to be displayed, they must be handled, handled, moved and moved many times. Only the film can effectively prevent mechanical damage such as scratches and scratches. For matte work, the adhesive in the film can penetrate into the void of the toner, reflecting the finest colors and increasing the color depth of the image. For bright light works, it can reduce the degree of surface reflection of the printed product and protect the human eye under the premise of obtaining the maximum color depth. Moreover, the film can improve the appearance of the product and stimulate the consumer's desire to purchase. In spite of the appearance of waterproof paper and waterproof ink, their price is double that of the film, and the effect is not as good as the film.

Film classification introduced

According to the process of coating can be divided into three types: dry coating, wet coating, oil coating. According to the nature of plastic film can be divided into: water coating, oil coating and pre-coated coating. The raw materials and equipment used in the lamination process can be classified into: a coating film process and a pre-coating process.

1. coating film

That is, the coating film is coated with an adhesive on the film first, and then hot-pressed, which is widely used in the present country.

In the past 10 years, the manufacturers who applied the gluing process to the compound production throughout the country have experienced a sudden burst of fire when the BOPP film was coated with glue, whether it was a paper/plastic composite or a plastic/plastic composite. ACCIDENT.

2. Pre-coated film

In the precoating film process, the adhesive is pre-coated on a plastic film, dried and wound, and then hot-pressed on a film-covering apparatus without an adhesive coating apparatus to complete the film coating process.

The pre-coating process eliminates the need for adhesive heating and drying systems for film-covering equipment, greatly simplifies the coating process, and is easy to operate. It can be used with the start-up, resulting in high flexibility; no solvent odor, no environmental pollution , Improve the working conditions; more importantly, it completely avoids the occurrence of bubble, delamination and other laminating failures. The transparency of the film products is extremely high, and it has broad application prospects and promotion value.

The precoating film structure consists of a substrate and a subbing layer. The substrates are usually PET and BOPP films. Considering the material cost and processing technology, most of the precoated film substrates use BOPP film. The thickness of the film is 12-20 mm, and the thickness of the adhesive layer is 5-15 mm. According to the different processing equipment and process conditions, use different thickness of the glue layer. The adhesive layer is divided into hot melt adhesive and organic polymer low temperature resin. The difference between the hot melt adhesive and the resin is that the hot melt adhesive is made of a mixture of main adhesive resin, a tackifier and a modifier, and the organic polymer resin is a single polymer low temperature copolymer.

Due to the limitations of process technology, production equipment and raw materials, there are still defects in the quality of the pre-coated films produced in China. Most of the pre-coated films produced in China are pre-coated films of hot-melt adhesives due to certain production processes. The colloid is dissolved in an organic solvent by a process similar to that of the coated film, and the roll is coated on the base film with a concave anilox roll. Therefore, there is an insufficient volatilization of the solvent, and an odor is generated during the operation. The solvent after the coating is applied. Volatilization, surface blistering and other phenomena; At the same time as the hot melt adhesive from a mixture of several polymer materials, in the course of use, poor temperature control will cause high-temperature polymer in the hot melt adhesive degradation and cross-linking, so that The surface quality of the coating film is not good; some precoating film adhesives are easily adhered to the outer surface of the substrate, resulting in poor winding; because the adhesive layer is thin, and the surface of the adhesive layer is not activated, the adhesiveness to the printed matter is likely to be insufficient. defect. Because the hot melt adhesive is made of a mixture of several materials, the transparency after coating is obviously inferior to that of a low temperature pure resin type.

The application of laminating technology covers a wide range of applications, such as the covers of books and magazines, albums, various documents, advertising brochures, posters, color printing cartons, and other paper products, and often uses a lamination process for surface treatment and processing to achieve better results. Appearance effect. In general, film-covered products have the following characteristics compared to general paper-based prints: the surface is smoother and brighter, the gloss is higher, the graphic and text are more vivid and three-dimensional; tear resistance, abrasion resistance and resistance High folding performance; good waterproof, anti-fouling, chemical resistance and other properties.

3. Waterborne film

Water-based film is a way to process the surface of the printed matter, improve the glossiness and strength of the surface of the printed matter, and enhance the aesthetic effect. It can make the printed material resistant to temperature, water, and abrasion, and is an effective means to improve the grade and value of the printed materials. Therefore, to measure the merits of film quality, it is also necessary to examine the brightness, strength, and adhesion of the film. The development of water-based laminating machine has made the water-based laminating technology widely used. The water-based wet laminating film has been favored by customers because of its features of high strength, high grade, easy recycling, and no pollution.

4. Curved surface film

Surface coating is actually a brand new transfer technology. The traditional printing or transfer printing is generally incapable of dealing with complex-shaped workpieces. The curved surface coating is not only easy to handle, but also applicable to different materials, and gives the product a lively pattern and color. Improve the added value of the product. This technology is a revolutionary new transfer technology for the 20th century. The surface coating is a special chemical treatment film. After being printed with a certain color pattern, the surface coating is applied to the surface of water. Using the effect of water pressure, the color texture pattern is evenly transferred to the surface of the product, and the covered film is Automatically dissolve, after cleaning and drying, a layer of transparent protective coating, then the product can show a completely different visual effect.

Curved application industry: 1 automotive supplies: instrument panel, control panel, tissue box, cup holder, tape holder, rear view frame, control handle, lock and so on. 2 electronic products: telephones, pagers, video recorders, televisions, air conditioners, speakers, remote controls, mice, watches and so on. 3 bedroom supplies: sofas, coffee tables, kitchen boxes, chandeliers, ashtrays, vases and other furnishings used containers. 4 days with fine: glasses, glasses box, pen, insert pen holder, desk calendar, art photo frame, racket, gift box, cosmetic box and so on. 5 indoor building materials: doors and windows, flooring, wallboard and so on.

The film coating process can be classified into cold (cold pressure) film, heat (heat live) film and liquid film according to the conditions of heat, pressure, and material. The hot film technology refers to the process of heating and activating the pre-coated adhesive on the film, and bonding the film and the printed product together; and the cold film is pressed directly to the adhesive. The film is bonded to the print. Both of these methods can produce various kinds of special films such as UV protection film, waterproof film, anti-friction film and so on. Recently, there has also emerged an emerging technology called "liquid coating," which involves brushing a clear liquid directly with a brush, a spray gun, a roller, or a special laminator on the surface of the product. This method is simple and inexpensive, but it is still not mature enough.

(to be continued)