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Film covering technology is a surface treatment technology after printing, also known as post-press plasticization, post-press film covering or post-press pasting. It refers to the product processing technology of covering a layer of transparent plastic film with a thickness of 0.0 12 ~ 0.020 mm on the surface of printed matter with a laminating machine to form a paper-plastic integration. Generally speaking, according to the process used, it can be divided into instant film and precoated film, and according to the different film materials, it can be divided into bright film and matt film.
extensive use
Therefore, laminating technology is widely used in all kinds of packaging and decoration printed matter, all kinds of books and periodicals, books, calendars, maps and so on. , is a very popular printing surface treatment technology. Film mulching technology entered China in 1980s. Because of its many advantages, it swept the country in a short time and gradually became the darling of book surface decoration. Nowadays, people's awareness of environmental protection has gradually increased, and relevant laws and regulations have been continuously improved. Pollution in the process of film mulching and the difficulty in reusing film mulching products after they are abandoned are two major problems in front of people. When it comes to film mulching, people often think of "white pollution". Many people in the industry have doubts about the role of plastic film and whether it can continue to be used. In order No.32 issued by the former State Economic and Trade Commission in 2002, the solvent-based instant coating and laminating machine was included in the third batch of obsolete production capacity, technology and products. To be sure, in the future development process, plastic film mulching technology will accept more and more tests. How will plastic film mulching develop? Is it completely eliminated or rationally developed? These problems will become unavoidable problems in the development of laminating technology.
Editing this paragraph is worrying.
When we visit the book exhibition, it is difficult to see the products covered with film on foreign booths. In some developed countries, laws and regulations on environmental protection, health and fire risk are relatively perfect, which makes it difficult for this technology to develop. On the contrary, the film-covered market in China is showing a "prosperous" scene. If we want to talk about book binding, we must talk about film covering technology.
1. Main problems in the process of film mulching
Although the solvent-based instant coating laminating technology has been introduced for many years, there are still many small laminating factories in China that continue to use it. It is understood that the process mainly has the following problems. (1) affects the health of operators and has fire hazards. Due to the use of benzene-containing solvents, solvent-based film mulching has damaged the health of operators and caused great pollution to the workshop environment. At the same time, with the increase of the concentration of surrounding organic solvents, the static electricity generated by thin film materials can easily cause sudden fires. Moreover, for the surrounding environment, the film-covered factory itself is a serious pollution source with potential danger. (2) It is difficult to recycle the coated paper film material, which wastes resources. It is understood that 80% of paper fibers in China now come from recycled waste paper, including paper wool and paper edges. In printed matter, the amount of paper used for the cover of books and periodicals is also huge. If a large number of film mulching materials (especially coated film mulching materials) are used, paper and plastic film can not be separated, then the waste paper, paper edges and paper wool after film mulching can not be recycled and degraded, which will bring immeasurable economic losses, which is actually a waste of resources.
2. The laminating process is backward, but there is still a market.
Since solvent-based film covering has such great harm, why is there such a big market? The following reasons more or less determine its reason for existence. First, the laminating machine of solvent-based adhesive has been used for many years, the equipment is mature and the bonding accuracy is guaranteed. These machines are generally not easy to break down and maintenance is not complicated. They have accumulated a lot of production and maintenance experience in long-term use, so many manufacturers are reluctant to eliminate this solvent-based laminating machine that can still be used. Second, the solvent-based laminating process has been popularized for decades, with mature technology and guaranteed product quality. Many enterprises and technicians are reluctant to replace a skilled technology with one they are not familiar with. Thirdly, considering the cost, the solvent-based laminating machine is still relatively cheap. For a printing factory, saving costs means striving for profits. Fourthly, although the water-based laminating process has improved the environmental problems in the production process and avoided the harm to operators, there are still many defects compared with the solvent-based laminating process, such as unsatisfactory product quality.
3. The attitude of printing house and publishing house affects the development of plastic film.
Generally speaking, it is a matter of time before the solvent-based laminating process is completely eliminated, and we also proved this trend through interviews. It can be predicted that it is time for solvent-based laminating to quit the historical stage. However, can we completely deny the film covering technology on this basis? In my opinion, under the current circumstances, it is unrealistic to completely eliminate the film covering technology. The following two aspects deserve our attention. (1) It's hard to give up the profits of the printing house. For most printing plants, film mulching is a big profit point of post-press processing, especially now that the printing industry has entered the era of low profit, it is difficult for printing plants to give up film mulching processing. Operators who cover the front line with plastic film are the first victims of harmful gases. What can comfort us is that the present printing houses (even some small-scale printing houses) are generally aware of the harm of plastic film mulching technology and are trying to minimize the possible pollution, such as adopting more environmentally friendly technologies and materials and improving the ventilation facilities of factories. They welcome environmentally friendly products, such as water-based films and pre-coated films. (2) laminating has become a habit. In the interview, the reporter found that the laminating process was highly praised by the press. When American editors choose the binding method of books and periodicals, they often prefer to cover the film, even if local UV glazing, they need to cover the film first and then polish. It can be said that the publishing house plays a decisive role in whether to cover the film or not, because according to the general book publishing process, the publishing house must first make a plan, and the printing house or binding factory is only implementing the wishes of the publishing house. Some science and education publishing houses cover almost all books. On the issue of environmental protection, publishing houses are obviously not as active as printing houses. With the improvement of people's living standards, the printing quality and surface decoration effect of paper publications have also been greatly improved. In order to pursue the sales of book products, publishers must make a big fuss about the covers of books and periodicals. Paper publications can be protected by plastic film, and the visual effect is better, especially the matte film gives people a soft, high-grade and comfortable feeling. In addition, film mulching can also increase the concentration and brightness of colors, improve color contrast, and be waterproof and non-sticky. At the same time, the physical properties of paper, such as tension value, smoothness, aging resistance, tear resistance and puncture resistance, are generally improved, which reduces the deformation and damage of paper products caused by moisture, improves the rigidity and molding stability of books, and greatly improves the added value of printed matter. Moreover, the investment of film-covering cost is far lower than the increase of product added value and commodity promotion rate. For publishers, since plastic film has so many advantages, why not? Therefore, publishing units should strengthen communication with printing plants, and printing plants should introduce the advantages and disadvantages of laminating technology to publishing units. Publishing units can consider the advantages and disadvantages of various technologies and design with a sense of social responsibility when formulating book binding schemes.
Edit this paragraph for development.
With the continuous progress of printing technology, printing materials are constantly updated, and the changeable factors of post-press processing conditions have an increasing influence on laminating, and the printing quality standards and market demand are constantly improving, which requires the laminating industry to adjust its structure according to the changes of objective conditions and new quality and technical standards. At the same time, we should also find some other technologies that can replace plastic film mulching in time to reduce the pressure of plastic film mulching on the environment.
1. Can light energy replace film mulching?
In fact, UV glazing can protect and decorate the surface of printed matter in addition to laminating process, and many functions are similar. Due to the relatively low cost of UV glazing, rapid development and attractive products, it also occupies a certain market share in some post-press processing fields. Some people who are optimistic about UV glazing technology even think that this technology can replace the film covering technology and develop independently. In fact, this is just a wish of people. According to some printing plants that have applied UV glazing technology, the most common application of UV glazing is local glazing, which can improve the quality of books, but in most cases, this local UV glazing process is also carried out after laminating, and the previous laminating process must be solvent-based laminating. In addition, compared with laminating, UV glazing has many disadvantages. For example, the protective effect, folding resistance and wear resistance of UV glazing. It is not as good as film covering, and it will have limitations in many fields, such as packaging boxes; UV glazing also needs printing equipment and UV curing equipment, and laminating has ready-made equipment foundation and mature technology; In addition, some UV varnish will also give off odor during painting, which will affect operators. Nowadays, printing houses and publishing houses attach great importance to this process, and think that UV glazing can replace the laminating process in book printing. But generally speaking, UV glazing is still limited in many aspects, and there are still many problems in process treatment, which can not completely replace the film covering process.
2. Pre-coating membrane technology
Pre-coated film refers to the process of rewinding plastic film in advance and then compounding it with paper printed matter. First, the pre-coated film processing factory will coat the glue solution on the film according to the different formats of the specifications used, then roll it up for users to choose, and then compound it with printed matter. Pre-coated film began to be used around 1989, and it has been widely used in Europe and America, and entered Asia around 1996. In Asia, Europe and the United States have announced that the use of instant coating films is prohibited and pre-coated films are used instead. Due to its late use, all countries in Asia (such as China and South Korea) except Japan are in the state of using pre-coated film and ready-to-use film simultaneously. China began to use precoated film after 2000, and now the market share of precoated film in China is still very small. Compared with instant coating, pre-coated film has many advantages. If pollution is reduced, there is no harm to human body; Will not affect the quality of film covering because of different paper properties or different ink colors; The pre-coated film laminating machine is simpler to operate and the processed picture and text effect is better; Basically eliminated wrinkles, bubbles, shedding and other phenomena. Most notably, this is an environmentally friendly process, and the whole production process is harmless to people's health. However, the popularity of pre-coated film in China is still relatively slow. Among them, the cost problem is a great influence factor, which determines the investor's enthusiasm for the pre-coating process. In a recent survey, more than half of the interviewees think that the price of precoated film products is high, because precoated film products belong to printing consumables, and the price cost is a problem that cannot be ignored when printing plants choose consumables. In addition, due to the lack of paper film separation technology in China, pre-coated film can not be completely called environmental protection process in China. In view of this situation, the cost of pre-coated film products should be reduced through large-scale production, so that the market price is closer to the needs of printing houses. At the same time, the research and development or introduction of paper-film separation technology should also attract the attention of relevant departments. Under the premise of not giving up film-covering technology, environmental protection film-covering can be realized and film-covering technology can be developed reasonably.
3 namely coating technology.
That is, the adhesive is coated on the film before hot pressing, but it is easy to catch fire in the production process.
4 Water-based film covering technology
It is a method to treat the surface of printed matter to improve the gloss and strength of printed matter surface and enhance the aesthetic effect. To measure the quality of plastic film, we also need to examine its brightness, strength and adhesion. Waterborne wet bonding is favored by customers because of its high strength, easy recycling and no pollution.
5. Curved surface coating technology
It is a brand-new extension technology, which can deal with complex workpieces and is suitable for different materials. The added value of products is greatly improved because of vivid patterns and colors. This technology is to print a certain color pattern on a specially chemically treated film, and then lay it flat on the water. Using water pressure, the pattern is evenly written on the surface of the product, and the coating film is automatically dissolved. After cleaning and drying, it is coated with a transparent protective coating. At this point, the product has presented a completely different visual effect. Lamination process can be divided into cold (cold pressing) lamination, hot (heat activation) lamination and liquid lamination according to cold and hot conditions and materials. Hot lamination technology refers to heating and activating the pre-coated adhesive on the diaphragm, and bonding the diaphragm and printed matter together through it; Cold mounting is to bond the film and printed matter together by pressure and directly relying on adhesive. These two methods can make various special films such as ultraviolet protective film, waterproof or antifriction film. Recently, a new technology called "liquid film covering" method has appeared. That is, the transparent liquid is directly coated on the product surface with a brush, a spray gun, a roller or a special laminator. Although the technology is simple and cheap, it is not mature at present. Small laminating machine laminating technology This small laminating machine is developed to meet the needs of middle and low-end consumers. This small laminating machine solves the fundamental problem of ordinary laminating machine. The price of laminator is between 1.400- 1.500 yuan. Because the internal heated rubber roller is used to press the film and feed the film up and down, the heating time of the pre-coated film is increased and the heating is balanced, so the film is smooth and bright, and the effect is the same as that of the high-grade laminating machine. The heating power of this small laminating machine is only 500W W. Although the temperature is adjustable, the speed is fixed, and the film can be laminated by 0.7-0.8 meters per minute. Suitable for business card sticking, recipe sticking, photo sticking and graphic printing sticking, especially for some small printing houses, typing and copying shops, business card making institutions and photo studios. In order to reduce equipment investment and cost, more laminators are selected. At present, this small laminating machine has a good market prospect. Many customers who used to use it for their own use later began to sell this kind of laminator, and the sales volume was also good. It can be said that this small laminator has the highest cost performance. Easy to use, obvious effect, meet the needs of some small terminal customers, [1] has great promotion value.
Edit the common quality problems of packaging film coverage in this paragraph.
The outer packaging of goods has become a problem that many manufacturers attach importance to. With the increasing demand of people, laminating technology is widely used in outer packaging, which makes the goods colorful and dazzling, and greatly arouses consumers' desire to buy. However, due to materials, technology, equipment, environment and other factors, there will be foaming, wrinkling, ink withdrawal, peeling and other phenomena. Let's talk about how to avoid the development of these phenomena according to the specific situation. After this phenomenon appeared, it immediately attracted the attention of factory quality management personnel. After detailed analysis by technicians, the reasons are roughly as follows:
1, the printed material itself
As a printed matter, the paper's own properties, the performance of ink and the density of printed pictures and texts all affect the quality of film covering. If the paper with poor uniformity is used for printing, the amount of ink absorbed by the format is inconsistent with the absorption speed; It will cause quantitative changes in paper tightness, uniformity, smoothness and moisture. When the printing layer of ink is too thick, the wettability, diffusivity and permeability of adhesive molecules are poor, the movement between molecules is relatively inactive, and the mechanical binding force is small. In addition, in the printing process, kerosene is often added to the ink, which makes the ink layer quickly conjunctival, resulting in the surface crystallization of the ink layer, the surface of the printed matter is smooth and tough, and the adhesive can not be wetted with it, which seriously affects the adhesion fastness.
2. The influence of process operation and printing environment on the quality of laminating.
When laminating products, first coat a layer of adhesive on the surface of plastic film. Although it is dry, it still can't meet the requirements of film mulching. At this time, the concentration of adhesive is diluted by adding quick-drying solvent, but the moisture content is too high, and air bubbles are easy to appear when laminating under pressure, and then peeling off. At the same time, the film is easy to absorb oil, moisture, dust and other substances in the air, thus reducing its surface function. Excessive humidity will also affect the volatilization of solvents in adhesives. Too much residual solvent will isolate the air in the membrane and make the membrane unable to adhere. At the same time, uneven roller pressure, uneven cots and dirt on cots will all cause wrinkles when laminating. Cause analysis and troubleshooting methods 1. Poor adhesion to the countertop 1, improper selection of adhesive, improper setting of glue application amount and incorrect proportioning measurement. The type and dosage of adhesive should be re-selected. 2. The diluent contains alcohol and water that consume NCO groups, so that the hydroxyl groups of the main agent do not react. High purity ethyl acetate should be used. 3. The surface of printed matter is dusted. Wipe gently with a dry cloth. 4. The ink layer of printed matter is too thick. The arrangement of that adhesive coat should be increased to increase the pressure. 5. The printing ink layer is not dried or completely dried. Hot pressing should be done again before gluing; Choose a binder with high solid content; Increasing the coating thickness of the adhesive; Increase the temperature of the drying channel, etc. 6. Adhesive is absorbed by ink and paper, resulting in insufficient coating. The coating amount should be re-established and set. 7, plastic film surface treatment is not enough or beyond the applicable period, so that the treated surface is invalid. Plastic film should be replaced. 8. Low pressure, high speed and low temperature. The temperature and pressure of plastic film mulching should be increased, and the vehicle speed should be reduced appropriately. 2. Bubble phenomenon 1, and the ink layer is wet. Hot pressing should be done again before gluing; Delay the film covering time and let it dry thoroughly. 2. The ink layer is too thick. The coating amount of adhesive should be increased, and the pressure and compounding temperature should be increased. 3, drying temperature is too high, the adhesive surface crusting. The drying temperature should be lowered. 4. The surface temperature of the compound roller is too high. The temperature of the compound roll should be reduced. 5. The film is wrinkled or slack, and the film is uneven or curly. The film should be replaced and the tension should be adjusted. 6. There are dust and impurities on the surface of the film. Should be cleaned up in time. 7, the adhesive coating is uneven, and the dosage is small. The coating amount and uniformity should be improved. 8, the adhesive concentration is too high, the viscosity is large, and the coating is uneven. Diluents are used to reduce the concentration of the adhesive. Third, the film is wrinkled 1, and the film conveying roller is unbalanced. The transfer rod should be adjusted. 2. The elasticity of both ends of the film is inconsistent or wavy. Qualified films should be replaced. 3. The adhesive layer is too thick, and the solvent is not completely evaporated, which affects the viscosity. When pressed by the press roller, the paper and the film slide. The coating amount should be adjusted to increase the temperature of the drying channel. 4. The ends of the electric heating roller and the rubber roller are unbalanced, the pressure is inconsistent, and the linear speed is different. Both rollers should be adjusted. [2]