Briefly describes the printing process of adhesive labels and its processing method

Before discussing the label printing process and its processing method, we must first understand what is the printing of the sticker, and it is different from the traditional label printing. Self-Adhesive Labels are also called self-adhesive labels, timely stickers, sticky notes, and pressure-sensitive papers. They are made of paper, film, or special materials. They are coated with adhesive on the back and are coated with silicon protective paper as a base paper. Composite materials, and after printing, die-cutting and other processing into a finished product label. The application requires only peeling from the bottom paper, and can be applied to the surface of various substrates with a single press, and labeling machines can also be used to automatically label the product on the production line.
Compared with traditional labels, adhesive labels do not need to be glued, pastes, water, pollution, and labeling time, and are convenient and quick to use in various situations. Different kinds of fabrics, adhesives, and backing paper types can be applied to materials that are not suitable for general paper labels. It can be said that: Self-adhesive is a universal label. The printing of stickers is very different from the traditional printing. Self-adhesive labels are usually printed and processed on the label linkage machine. Multiple processes are completed at once, such as graphic printing, die-cutting, waste disposal, cutting, or restoration. Volume and so on. That is, one end of the raw material for the entire volume is input, and the other end is the finished product. Finished products are divided into single-sheet or roll labels, and finished labels can be directly applied to goods. Therefore, the label printing process is more complex and the requirements for equipment performance and printing staff quality are also higher.
When we talk about the process of label printing, we must also understand the basic structure of the adhesive material as a printing material and the function of each part. The structure of the self-adhesive material is composed of three parts: surface material, adhesive, and backing paper. However, from the point of view of manufacturing process and quality assurance, the self-adhesive material consists of seven parts:
1. The surface coating is used to change the surface characteristics of the surface material. Such as improving the surface tension, changing the color, adding a protective layer, etc., to make it more acceptable ink and easy to print, to prevent dirt, increase ink adhesion, and to prevent the printing of graphics off. Surface coating is mainly used for non-absorbent materials such as aluminum foil, aluminized paper, and various types of film materials.
2. The surface material is the surface material, which is the material that accepts the printed graphic below, accepts the adhesive on the back surface, and is finally applied to the attached object. In general, any flexible deformable material can be used as a self-adhesive material fabric, such as commonly used paper, film, composite foil, all kinds of textiles, thin metal sheet and rubber and so on. The type of face material depends on the final application and the printing process. Surface materials should be able to adapt to printing and printing, have good ink resistance, and have enough strength to be able to accept a variety of processing, such as die cutting, waste, slitting, punching and labeling.
3, coating the bottom layer of the same with the surface coating, just coated on the back of the surface material, the underlying purpose is:
(1) Protect surface materials to prevent adhesive penetration;
(2) increase the opacity of the fabric;
(3) increase the adhesive force between the adhesive and the surface material;
(4) Prevent the plasticizer in the plastic surface material from penetrating into the adhesive, affecting its adhesive properties, resulting in a decrease in the adhesive force of the label and the label falling off.
4. Adhesives The adhesive is the medium between the label material and the bonding substrate and acts as a bonding agent. According to their characteristics can be divided into two kinds of permanent and removable. It has a variety of recipes for different face materials and different occasions. Adhesives are the most important component of self-adhesive material technology and are key to the application of labeling technology.
5, release coating layer (coated silicon layer)
That is, the surface of the base paper is coated with a silicone oil layer. The application of silicone oil can make the bottom line a surface with a very low surface tension and a very smooth surface. The function is to prevent the adhesive from sticking to the bottom line.
6. The function of the backing paper is to receive release agent coating, protect the adhesive on the back of the face material, support the surface material, enable it to die-cut, discharge and label on the labeling machine.
7. Back-coating or back-printing The back-coating is a kind of protective coating on the back of the backing paper to prevent the adhesive around the label from being discharged and re-wound to the backing paper. Another role is to make multilayer labels. The back printing function is to print the registered trademark or pattern of the manufacturer on the back side of the backing paper, which serves as a propaganda and anti-counterfeiting effect.
What kinds of stickers do you have? There are five categories:
Classified by adhesive properties, can be divided into permanent adhesive materials and removable adhesive materials;
Classified by adhesive coating technology, can be divided into hot-melt adhesive materials, solvent-type adhesive materials and emulsion adhesive materials;
According to the classification of adhesives and chemical properties, it is divided into rubber-based and acrylic adhesive materials;
Classified according to the characteristics of the bottom paper, it is divided into opaque bottom paper, translucent bottom paper and transparent bottom paper three kinds of self-adhesive materials;
Classified according to the characteristics of surface materials, divided into paper stickers, film stickers and special stickers.
Finally, we talk about the specific printing and processing technology of stickers and self-adhesive film labels according to the classification of surface materials:
First, the printing process of the paper sticker label 1. The printing process flow Different types of materials, labels for different purposes, the process used is also different. The general label printing press is a multi-functional equipment, and the processing plant can make printing processing according to customer requirements. Adhesive label printing process flow is as follows:
(1) Unwinding a batch type; no tension changes when the roll is unwound, so no adjustment is required. It is applied on flat and flat pressed labelers, and the unwinding speed is slow. Due to the absence of paper positioning correction devices for such devices, it is required that the end face of the web be clean to ensure accurate overprinting during printing.
b Continuous: applied to the round transformation label machine. Since the tension of the paper is changed when the diameter speed of the paper roll changes, this device has tension automatic or manual control mechanism, and web correction correcting device to ensure stable paper feeding and ensure printing quality.
(2) Flattening of bronzing: It is applied to round flat and flat flat label machines with low speed.
Round press circle: It is applied to the round press label printing machine. It is fast and can be used for continuous hot stamping. It is rarely used. Generally, the gold printing process is used instead of hot stamping.
(3) Print flattening; suitable for printing of small areas and simple patterns, such as price tags, bar codes, etc.
Flattening: For label printing with a field-oriented, general pattern, simple color-tone printing.
Round press circle is suitable for all kinds of pattern label printing, especially for high-grade color mesh label printing.
UV printing: In the above three printing methods, plus UV drying, you can print thin film adhesive material.
(4) First hot stamping, after printing on equipment without UV drying, using ordinary ink, the disadvantage is that the design of the printing pattern is limited.
(5) First printing, post-bronze application On the equipment with UV drying device, the ink is quickly dried and then hot stamped on the ink. The hot stamping pattern can be designed arbitrarily, is not limited by the ink, and is suitable for high-grade label printing. Kind of advanced production technology.
(6) Polishing on the ground: coating the surface of the ink with a layer of varnish for the purpose of protecting the ink layer, preventing moisture, waterproofing, and improving the surface gloss. The UV film can be used instead of a lamination process.
(7) Films are filmed on paper or film materials in order to protect the ink, waterproof, moisture, increase the strength of the label, and increase the three-dimensional pattern. Duplex film is divided into bottomed paper laminating film and non-backed paper laminating film, which is generally adopted because of its low cost. According to the requirements of the process, there are two kinds of compound packaging machine, target=_blank, transparent film and matt film, and the former is more commonly used.
(8) Hole punching applications are not common and are mainly used for computer printed labels. The requirement is to place a positioning drive hole on both sides of the tag, or a label applied on the price tag gun. It is required to make a hole in the middle of the tag for positioning and driving.
(9) Die-cut adhesive label cutting is a semi-cut process, which only cuts through the surface material and retains the backing paper. Divided into two processing methods: such as flat die cutting, suitable for all types of label printing presses, artificial plate, low cost, short plate-making cycle, but low viscosity, suitable for short live printing and processing. At present, almost all domestic label factories use flat die cutting. The other is circular die-cutting, which is applied to round-pressed round label equipment. It has high speed and high die-cutting viscosity and is suitable for long-lived work. The disadvantage is that the plate making cost is high and the cycle is long. At present, the domestic manufacturers of die-cutting rolls are generally processed abroad. (10) The delivery can be roughly divided into cut sheet delivery and folding delivery.
2. Processing methods for paper labels (1) Sheet-fed printing methods for such self-adhesive materials, offset printing accounts for 95%, embossing accounts for 2%, screen printing accounts for 2%, and computers and printing account for 1%. . The self-adhesive label printing of sheet-fed paper is the same as that of ordinary printed matter, and each process is completed on a single machine. The production efficiency is low, the consumption is large, and the cost is high, but the printing quality is good. If the offset printing process is adopted, the quality of the labels printed by the four colors is much better than that of similar products printed by the label printers. However, since the self-adhesive products printed on sheet-fed paper are sheet-fed and cannot be rewound, such products can only be manually labeled. Sheet-fed printing is suitable for large-area self-adhesive color prints. Such as posters, posters, and large-area labels are not limited to label products. It can be said that self-adhesive sheet-fed printing is an important part of the adhesive printing industry.
(2) In the printing method of web-type adhesive web materials, currently, 97% of embossing printing, 1% of screen printing, 1% of offset printing, and 1% of flexographic printing. Due to the use of web printing, all processes are completed on one machine, resulting in high production efficiency, low consumption, and low cost. At present, China's label printing presses are in the form of letterpress printing, with few functions, and are only suitable for printing labels with simple color blocks and lines. The printing quality is inferior to that of single-sheet offset printing. However, the label processed by the web can be re-wound into a roll, and can be applied to an automatic labeling machine, a bar code printer, an electronic scale, and the like, and can be easily automated. Web printing stickers are currently the mainstream of adhesive printing in the world.
Second, the film type of adhesive printing and processing technology Compared with ordinary paper, film material has many advantages, film material printing is the future direction of adhesive printing. We briefly introduce the structural characteristics, printability, and post-printing process of thin film materials:
1. Structure and characteristics of thin film materials (1) Structure The thin film material has the same structure as the paper material. The only difference is that the material surface needs to be treated.
(2) Surface characteristics and processing methods The principle of the ink layer forming a pattern on printed matter is penetration, volatilization, conjunctiva, and curing. Due to the high density of the film, the ink is only volatilized, conjunctiva, and does not penetrate during the curing process. Therefore, the surface of the film needs special treatment. The role of surface treatment is to increase the surface tension of the film, making it greater than the surface tension of the ink, so as to achieve the correct combination of ink and film materials. Surface treatment is usually the following methods: 1 corona treatment: the high voltage charge discharge treatment to the film surface, and ultimately to increase the surface energy of the surface tension purposes. Corona treatment is generally carried out at a thin film manufacturing plant. Since the surface tension is time-limited, it requires strict inspection before printing. Therefore, some advanced equipment has a pre-press corona treatment device to print high-quality film products.
2 Print processing: chemically changing the surface characteristics of the film to make it suitable for ink printing or ribbon printing.
3 surface coating: the use of chemical coating on the film surface, increase the surface tension, change the surface properties.
2. Process for printing thin-film materials (1) Method for printing thin-film materials The basic printing methods include gravure: gravure solvent ink and gravure aqueous ink; offset: UV offset ink printing; embossing: common resin Ink printing and UV embossing ink printing; flexo printing: water-based ink printing, solvent ink printing and UV ink printing; screen printing: divided into UV ink printing and solvent ink printing; combined printing: divided into embossing + screen printing, embossing + Flexo, flexo + silk screen, offset + letterpress four printing methods. Here are some more specific printing methods used:
1 ordinary resin ink printing. This is the most common method currently used. There are two kinds of dryness due to the problem of drying.