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2022-10-16
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Talking about the printing process of self-adhesive labels

before talking about the printing process and processing methods of self-adhesive labels, we should first understand what is the printing of self-adhesive labels and what is the difference between it and traditional label printing. Self adhesive labels are also called self-adhesive labels, such as timely stickers, instant stickers, pressure-sensitive paper, etc. they are a composite material with paper, film or special materials as the fabric, adhesive coated on the back, and silicon coated protective paper as the backing paper. After printing, die cutting and other processing, they become finished labels. When applied, it only needs to peel off the backing paper and press it gently to stick to the surface of various substrates. It can also use the labeling machine to automatically label on the production line

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 apply in various occasions. All kinds of labels with different surface materials, adhesives and backing paper can be applied to materials that general paper labels cannot do. 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 raw materials of the whole roll, 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

while talking about the printing and processing technology of self-adhesive labels, we must also understand the basic structure and functions of various parts of self-adhesive materials as printing materials. The structure of self-adhesive material is composed of three parts on the surface, namely, surface material, adhesive and backing paper. However, from the perspective of manufacturing technology and quality assurance, self-adhesive material is composed of seven parts:

1, surface coating

is used to change the surface characteristics of surface materials. For example, improve the surface tension, change the color, increase the protective layer, make it better accept the ink and easy to print, so as to prevent dirt, increase the adhesion of the ink and prevent the falling off of the printed text. Surface coating is mainly used for non absorbent materials, such as aluminum foil, aluminized paper and various film materials

2. Surface material

refers to surface material, which is the material that receives printed graphics on the front and adhesives on the back and is finally applied to the pasted object

generally speaking, all flexible and deformable materials can be used as fabrics of self-adhesive materials, such as commonly used paper, film, composite foil, all kinds of textiles, thin metal sheets and rubber, etc. The type of surface material depends on the final application and printing process. The surface material should be able to adapt to printing and printing, have good inking, and have enough strength to accept various processing, such as die cutting, waste discharge, slitting, punching and labeling

3. The bottom coating is the same as the surface coating, but it is coated on the back of the surface material. The main purpose of the bottom coating is:

(1) protect the surface material and prevent the penetration of adhesive

(2) increase the opacity of the fabric

(3) increase the adhesion between the adhesive and the surface material

(4) prevent the plasticizer in the plastic surface material from penetrating into the adhesive, affecting its adhesive performance, resulting in the reduction of the adhesive force of the label and the falling off of the label

4. Adhesive

adhesive is the medium between label material and bonding substrate, which plays a connecting role. According to its characteristics, it can be divided into permanent and removable. It has a variety of formulas, suitable for different surface materials and different occasions. Adhesive is the most important component of self-adhesive material technology and the key of label application technology

5. Release coating (coating silicon layer) can carry out experiments and provide data according to GB, ISO, JIS, ASTM, DIN, JG, JT, Yb, QB, YD, YY, QC, sy, SL, BB, Hg and other international standards and industry standards. Coating silicon oil on the surface of the backing paper can make the backing paper become a very low surface tension and smooth surface, and its function is to prevent the adhesive from sticking to the backing paper

6. Backing paper

the function of backing paper is to receive the release agent coating, protect the adhesive on the back of the surface material, support the surface material, and enable it to carry out die cutting, waste discharge and labeling on the labeling machine

7. Back coating or back printing

back coating is a protective coating on the back of the backing paper to prevent waste discharge. The adhesive around the rewound label is bonded to the backing paper. Another function is to manufacture multi-layer labels. The function of back printing is to print the manufacturer's registered trademark or pattern on the back of the backing paper, which plays the role of publicity and anti-counterfeiting

what are the types of self-adhesive materials? There are five categories:

according to the characteristics of adhesives, they can be divided into permanent adhesive materials and removable adhesive materials

according to the classification of adhesive coating technology, it can be divided into hot-melt adhesive materials, solvent adhesive materials and emulsion adhesive materials; (not very understood)

according to the classification of adhesives and chemical properties, it is divided into rubber based and acrylic self-adhesive materials

according to the characteristics of backing paper, it is divided into three kinds of self-adhesive materials: opaque backing paper, translucent backing paper and transparent backing paper

according to the characteristics of surface materials, it is divided into paper self-adhesive materials, film self-adhesive materials and special self-adhesive materials

finally, we will talk about the specific printing and processing technology of self-adhesive film material labels of self-adhesive paper according to the classification of surface materials:

I. printing and processing technology of paper self-adhesive labels

1. Printing and processing technology process

different kinds of materials and labels for different purposes, the process flow used is also different. Generally, the label printing machine is a multi-function equipment, and the processing factory can formulate the printing process according to the requirements of customers. The process flow of self-adhesive label printing is as follows:

(1) unwinding

a intermittent type: there is no tension change when the web is unwinded, so it does not need to be adjusted. It is used in flat and round flattening label machines, and the unwinding speed is slow. Since such equipment has no paper positioning correction device, the end face of the web is required to be clean to ensure accurate overprint during printing

b continuous type: it is applied to the rotary label press. As the tension of the paper changes when the diameter and speed of the web change, this device has an automatic or manual tension control mechanism and a web deviation correction device to ensure stable paper feeding and printing quality

(2) bronzing

flattening: several precautions should be put forward for the hardness tester of Jinan experimental machine factory. It is used on the circular flattening and flattening label machine, and the speed is low

round pressing: it is applied to the round pressing label printing machine, which is fast and can be bronzed continuously. It is rarely used, and the gold printing process is widely used instead of bronzing

(3) printing

flattening: suitable for small-area, simple pattern printing, such as price labels, bar codes, etc

round flattening: it is suitable for label printing with field and general patterns, and can be used for simple color eye tone printing

round pressing is suitable for all kinds of pattern label printing, especially for high-grade color eye tone label printing

uv printing: in the above three printing methods, film adhesive materials can be printed after UV drying

(4) bronzing first and then printing

on the equipment without UV drying, ordinary ink is used. The disadvantage is that the design of printing pattern is limited

(5) printing first and then bronzing

it is applied to the equipment with UV drying device. The ink is quickly dried and then bronzed on the ink. The bronzing pattern is arbitrarily designed, which is not limited by the ink. It is suitable for the printing of high-grade labels. It is an advanced production process

(6) glazing

field glazing: apply a layer of varnish on the surface of the ink to protect the ink layer from moisture, water and improve the surface gloss. It can replace the lamination process and adopt UV drying method

(7) laminating

laminating on paper or film materials is to protect ink, waterproof and moisture-proof, increase label strength, and increase the three-dimensional sense of pattern. Lamination is divided into backing paper lamination and backing paper lamination, which is widely used at present because of its low cost. According to the requirements of the process, there is a composite packaging machine 'target=_ Blank> there are two kinds of transparent film and matte film. The former is widely used

(8) punching

is not widely used and is mainly used for labels printed by computers. It is required to punch positioning driving holes on both sides of the label, or for the label applied on the price gun, it is required to punch holes in the middle of the label for positioning and driving

(9) die cutting

the die cutting of self-adhesive labels is a semi cutting process, that is, only the surface material is cut through and the bottom paper is retained. There are two processing methods:

such as flat die cutting, which is suitable for all kinds of label printing machines. Manual plate making, with low cost, short plate making cycle, but low viscosity, is suitable for short version live printing processing. At present, almost all domestic label factories use flat die-cutting. The other is circular die-cutting, which is applied to circular pressing label equipment. It has fast speed and high die-cutting viscosity, and is suitable for long-term printing. The disadvantage is that the cost of plate making is large and the cycle is long. At present, the die-cutting rollers of domestic manufacturers are generally processed abroad

(10) paper receiving

can be roughly divided into cutting paper receiving and folding paper receiving

2. Processing methods of paper self-adhesive labels

(1) among the printing methods of sheet fed

self-adhesive materials, offset printing accounts for 95%, embossment printing accounts for 2%, silk screen printing accounts for 2%, and computer and printing accounts for 1%. The self-adhesive label printing of single sheet paper is the same as that of ordinary printed matter. Each process is completed on a single machine, which has low production efficiency, high consumption and high cost, but the printing quality is good. If the offset printing process is adopted, the quality of labels printed by four-color color printing is much better than that of similar products printed by label printing machine. However, since the self-adhesive finished product printed on sheet fed paper is in the form of sheet fed paper and cannot be rewound, such products can only be labeled manually and cannot be automatically labeled on the automatic labeling machine. Sheet fed printing is suitable for large-area self-adhesive color printing. Such as posters, posters, large-area labels, etc., are not limited to label products. It can be said that sheet fed self-adhesive printing is an important part of the self-adhesive printing industry

(2) web paper

among the printing methods of Web self-adhesive materials, embossing accounts for 97%, silk screen printing accounts for 1%, offset printing accounts for 1%, and flexo printing accounts for 1%. Due to the use of web printing processing, all processes are completed on one machine, so the production efficiency is high, the consumption is low, and the cost is low. At present, the label printing machine in China is in the form of relief printing, with few functions. It is only suitable for printing labels with simple color blocks and line patterns, and its printing quality is not as good as that of sheet fed offset printing labels. However, labels processed with web paper can be rewound into rolls, which can be applied to automatic labeling machines, bar code printers, electronic scales and other equipment for automatic production. Web printed self-adhesive labels are the mainstream of self-adhesive printing in the world

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there is a definite distinction between them. The printing processing technology of film self-adhesive

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 film materials:

1. Structure and characteristics of film materials

(1) structure

film materials are the same as paper

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