Talk about label printing process

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, pressure-sensitive paper, etc. They are made of paper, film or special materials, coated with adhesive, and coated with silicon protective paper as a kind of backing 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, self-adhesive labels do not need glue, no paste, no water, no pollution, save labeling time, and are convenient and quick to use in various situations. Different types of labels for different fabrics, adhesives, and backing papers can be applied to materials that are not suitable for general paper labels. It can be said that stickers are a universal label. The printing of self-adhesive labels is very different from traditional printing. Self-adhesive labels are usually printed on the label coupler and multi-processes are completed at one time, such as graphic printing, die-cutting, waste disposal, cutting, or reworking. 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, surface coating

Used to change the surface properties of the face 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 the adhesion of ink 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 film materials.

2, surface material

That is, the surface material is a material that accepts the printed graphic on the front side, receives the adhesive on the back side, and is finally applied to the attached article.

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 a good ink, and have enough strength to accept a variety of processing, such as die cutting, waste, slitting, punching and labeling.

3, coating

The same as the surface coating, it is just coated on the back of the face material. The main purpose of the coating is:

(1) Protect the surface material 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 face material from penetrating into the adhesive, affecting the adhesive properties, resulting in a decrease in the adhesive force of the label and the label falling off.

4, adhesive

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 ingredient in adhesive material technology and are key to the application of labeling technology.

5, release coating (silicon coating layer) that is coated on the bottom surface of the silicone oil layer, the coating of silicone oil can make the bottom surface of the paper surface tension is very low, very smooth surface, the role is to prevent the adhesive bond in the bottom paper on.

6, bottom paper

The role of the bottom paper is to receive the release agent coating, protect the adhesive on the back of the face material, support the face material, enable it to die cut, waste and labeling on the labeling machine.

7, back or back

Back coating is a protective coating on the back of the backing paper to prevent waste, and the adhesive around the rewinded label is attached 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-based adhesive materials and emulsion-type adhesive materials; (not very understand)
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 self-adhesive film material labels for self-adhesive paper according to the classification of surface materials:

First, the printing process of paper labels

1, printing process flow Different types of materials, different uses of the label, the process used is also different. The general label printing press is a multi-functional device, and the processing plant can formulate the printing processing technology according to the customer's requirements. Adhesive label printing process flow is as follows:

(1) Unwinding A intermittent: No tension changes when the roll is unwound, so no adjustment is required. It is applied on the flat and round flat labeler, 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 type: applied in the round transformation round 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) Hot stamping flattening: It is applied on the flattening and flattening labeling 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) Flattening of printing: Suitable for printing of small areas and simple patterns, such as price tags, bar codes, etc.
Round flattening: For label printing with field, general pattern, simple color halftone 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, then printed on a device without UV drying, using ordinary ink, the disadvantage is that the design of printing patterns is limited.
(5) First printing, post-bronze application In the equipment with UV drying device, after the ink is quickly dried, the ink is bronzing. The bronzing pattern can be designed arbitrarily and is not limited by the ink. It is suitable for the printing of high-grade labels. Advanced production process.
(6) Polishing on the ground: coating the surface of the ink with a layer of varnish, aiming at protecting the ink layer, preventing moisture, waterproofing and improving the surface gloss. It can replace the lamination process and adopt the UV drying method.
(7) Films are laminated on paper or film material to protect ink, waterproof, moisture, increase label strength, 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. At present, almost all domestic label factories use flat die-cutting methods. The other is circular die-cutting, the application of a round pressure round label equipment, fast speed, high die-cutting viscosity, suitable for long-lived, the disadvantage is the large plate making cost, long cycle. 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 Method of Paper Labels

(1) Sheet-fed paper The printing method of such self-adhesive materials includes offset printing accounting for 95%, embossing printing 2%, screen printing 2%, and computer and printing 1%. The self-adhesive label printing of sheet-fed paper is the same as that of ordinary prints, and each process is completed on a single machine. The production efficiency is low, 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 form of the self-adhesive sheet-fed printing product is a sheet of paper and cannot be rewound, such products are only hand-labeled and cannot be automatically labelled on an automatic labeling machine. Sheet-fed printing is suitable for large-area self-adhesive color prints. Such as posters, posters, large-area labels, etc., 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) Web

In the printing method of web-type self-adhesive materials, currently, 97% of the printing area, 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. They are only suitable for printing simple color blocks, and labels with line patterns are not as good as those for sheetfed offset printing in terms of printing quality. However, the label processed by the web can be re-wound into a roll, which can be applied to automatic labeling machines, bar code printers, electronic scales and the like, and can be easily automated. Web printing stickers are currently the mainstream of adhesive printing in the world.
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one. Thin film adhesive printing process

Compared with ordinary paper, film material has many advantages. Film material printing is the direction of future adhesive printing. We briefly describe the structural characteristics of the film material, printability and post-printing process:

1, the structure and characteristics of film materials

(1) Structure

The film material has the same structure as the paper material, with the only difference being that the material surface needs to be treated.

(2) Surface characteristics and treatment methods

The principle of the ink layer forming a pattern on the print is penetration, volatilization, conjunctiva, and curing. Due to the high density of the film, the ink only evaporates and conjunctiva. No penetration of the curing process, the film surface 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 usually has the following methods:

A corona treatment: The high-voltage charge discharge treatment to the film surface, and ultimately to increase the surface energy of the purpose of the surface tension. 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.
B. Print processing: Chemically alters the surface characteristics of the film to make it suitable for ink printing or ribbon printing.
C surface coating: the use of chemical coating on the surface of the film, increase the surface tension, change the surface characteristics.

2, the printing process of film materials

(1) Printing Process of Thin Film Materials

The basic printing methods are gravure printing: gravure printing solvent ink printing and gravure water printing ink printing; offset printing: UV offset printing ink printing