Printing technology of the hottest film adhesive m

2022-08-07
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The printing process of film self-adhesive materials

compared with traditional labels, self-adhesive labels do not need to brush glue, paste, dip in water, have no pollution, save labeling time, and are convenient and fast to be used in various occasions. Various labels of different fabrics, adhesives and backing paper can be applied to materials that general paper labels are not competent for. It can be said that self-adhesive is a universal label. The printing of self-adhesive labels is very different from the traditional printing. Self adhesive labels are usually printed and processed on the label linkage machine, and multiple processes are completed at one time, such as graphic printing, die cutting, waste discharge, sheet cutting or rewinding. That is, one end is the input of the whole roll of raw materials, and the other end is the output of finished products. Finished products are divided into single sheet or roll labels, and finished product labels can be directly applied to commodities. Therefore, the self-adhesive label printing process is more complex, and the requirements for equipment performance and printing staff quality are also higher

compared with ordinary paper, film material has many advantages, and film material printing is the direction of self-adhesive printing in the future. Let's briefly introduce the structural characteristics, printability and post press processing technology of the film material:

1. The structure and characteristics of the film material

(1) the structure

the film material has the same structure as the paper material, and the only difference is that the material surface needs to be treated

(2) surface characteristics and treatment methods

the principle of ink layer forming pattern on printed matter is penetration, volatilization, conjunctiva and solidification. Due to the high film density, the ink only volatilizes and the conjunctiva. There is no penetration during the curing process, so the film surface needs special treatment. The function of surface treatment is to improve the surface tension of the film, so that it is greater than the surface tension of the ink, so as to achieve the correct combination of ink and film materials. Surface treatment usually has the following methods:

corona treatment: discharge treatment is carried out to the film surface through high-voltage charge, and finally the purpose of increasing surface energy, namely surface tension, is achieved. Corona treatment is generally carried out in the film manufacturer. Since the surface tension is time limited, it is required to strictly test it before printing. Therefore, some advanced equipment have pre press corona treatment devices to print high-quality film products

printing treatment: chemical methods are used to change the surface characteristics of the film to make it suitable for ink printing or ribbon printing

surface coating: coating on the film surface with chemicals to increase the surface tension and change the surface characteristics

2. Printing process of thin film materials

(1) printing process of thin film materials

the basic printing methods include gravure: gravure solvent ink printing and gravure water-based ink printing; Offset printing: UV offset printing ink printing; Embossing: it is divided into ordinary resin ink printing and UV embossing ink printing; Flexo printing: divided into water-based ink printing, solvent ink printing and UV ink printing; Screen printing: UV ink printing and solvent ink printing; Combined printing: there are four printing methods: embossing + silk screen printing, embossing + flexo printing, flexo + silk screen printing, offset + embossing. Next, several commonly used printing methods are introduced in detail. They are force measurement by force sensor:

a, common resin ink printing. This is the most commonly used method at present. Due to the drying problem, there are two drying methods: cutting sheets and putting them on shelves for drying. This method has a long drying time, and the plastic molded parts occupying the ground have a large anti-bacterial effect and are easy to rub dirty. Lamination. Wrap the non dried ink between the films, and pay attention to avoid laminating on the publication, so as to prevent laminating failure

b, UV ink embossing. This method has good printing quality and high efficiency. It is the most developed and most suitable printing process in China. As the domestic embossing equipment generally does not have UV devices, film printing is limited, so equipment updating and transformation is a necessary condition for printing film

c, solvent ink flexo printing. This is a traditional printing method with good quality. Due to the low surface tension of solvent inks, the requirements for film surface tension are not as strict as other inks, so the ink layer is strong and the process is relatively simple. However, solvent is a kind of printing method that will soon be eliminated because it affects environmental protection and is harmful to human body

d, water-based ink flexo printing. This is the most advanced printing method in the world today, with low cost, good quality and pollution-free. However, the process requirements are strict. The surface tension of the film must be above 40 dyne. There are strict requirements on the pH value and viscosity of the ink. This process is a process developed vigorously in China, but its development is very slow due to the limitation of equipment

e, UV ink flexo printing. Features the same as UV embossing, high cost, but the film surface tension requirements are relatively lax. Most manufacturers use water-based ink for printing. UV glazing can reduce the cost and increase the printing effect

f, UV ink screen printing. This new process can be used for single sheet or web printing, with high cost and good quality. The single sheet printing does not need to be put on the shelf for drying, and the drum printing can be carried out at a high speed

g, solvent ink screen printing. This is a traditional process. Generally, single sheets are printed by hand and reel materials are printed by linkage machine. More than 95% of them are single sheet printing, with good effect and low cost. However, solvent screen printing ink is harmful to human body and pollutes the environment

h, UV offset ink. As the resin ink is used, the film cannot be printed by ordinary offset printing. Some manufacturers use the method of single sheet overprint, shelf drying and finally laminating when printing PVC. However, because the ink is not easy to dry and easy to rub dirty, it causes waste and low productivity. The use of UV offset printing is to avoid all the above problems, and can print a high level of layered film products

i. intaglio printing. Gravure printing rarely prints self-adhesive, but the printing quality is the best of all printing methods, which is a potential printing method. In China, as long as the post press processing is solved, the existing equipment can print high-quality self-adhesive labels in the afternoon of October 27

j. combination printing, also known as composite printing, is the most advanced printing method in the packaging and printing industry in the world. According to different pattern designs, several printing methods are adopted on the same pattern to achieve the best visual effect. This kind of equipment is very common abroad. There are two types in China: sr-520b of Japan's Lintec and f-330 of shiky company. The former is embossing + silk screen printing, and the latter is offset + embossing

(2) ink drying method

according to the drying characteristics, the ink on the film can be divided into: oxidative polymerization drying (tree finger ink), volatile conjunctival drying (solvent ink), evaporative conjunctival drying (water-based ink) and UV curing drying (UV ink)

the drying methods are divided into: hot air drying, electric heating drying (far infrared ray type), ultraviolet curing drying

requirements for drying: the ink shall be fully dried; It does not affect the physical and chemical properties of the film; Does not affect the properties of the adhesive; No effect on the backing paper

methods to improve the drying effect of ink:

a. use additives to improve the drying speed of ink. Such as resin ink with dry oil; Water based ink plus special additives, solvent ink plus low boiling point solvent. However, it should be noted that the additive will change the brightness and brightness of the ink. The adhesive strength between the ink and the film cannot be affected by the additive

b. change the running speed of the film material

c. changing the temperature in the drying box is the method most search engines use at present. Change the temperature or the intensity of the ultraviolet light source

d. select appropriate film materials

(3) post press processing technology

the post press processing technology of film materials is roughly the same as that of paper labels. Such as bronzing, laminating, punching, folding, cutting, rewinding, waste discharge, die-cutting, etc. are used for the post press processing of film label

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