Printing process of paper and film stickers
Self-adhesive labels are also called self-adhesive labels, timely stickers, instant stickers, pressure-sensitive paper, etc. It is a kind of paper, film or special material as the fabric, the back side is coated with adhesive, and the silicon protective paper is used as the bottom paper. Composite materials, and after printing, die-cutting and other processing become finished labels. In application, just peel off from the base paper and gently press it to stick to the surface of various substrates, or use the labeling machine to automatically label on the production line.
Compared with traditional labels, self-adhesive labels do not need to be glued, pasted, or dipped in water. They are pollution-free, save labeling time, and are convenient and fast for various occasions. Various types of labels with different fabrics, adhesives and backing paper can be applied to materials that are not qualified for general paper labels.
The printing of self-adhesive labels is very different from that of traditional label printing. Adhesive labels are usually printed and processed on the label interlocking machine, and multiple processes are completed at one time, such as graphic printing, die cutting, waste disposal, cutting or re-printing. Volume etc. That is, one end inputs the entire roll of raw materials, and the other end outputs the finished product. The finished product is divided into single or roll labels, and the finished product label can be directly applied to the goods. Therefore, the printing process of self-adhesive labels is more complicated, and the requirements on equipment performance and the quality of printing staff are also higher.
The basic structure of the self-adhesive material and the function of each part. The structure of the self-adhesive material is composed of three parts from the surface, namely surface material, adhesive and backing paper, but from the perspective of manufacturing process and quality assurance, the self-adhesive material is composed 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 better to accept ink and easy to print, to achieve the purpose of preventing dirt, increasing the adhesion of ink and preventing the printing of text. Surface coating is mainly used for non-absorbent materials, such as aluminum foil, aluminized paper and various film materials.
2. The face material, that is, the surface material, is a material that accepts printed graphics on the front and accepts adhesive on the back and is finally applied to the adherend.
Generally speaking, any material that can be deformed flexibly can be used as a fabric for self-adhesive materials, such as commonly used paper, film, composite foil, various types of textiles, thin metal sheets and rubber. The type of face material depends on the final application and printing process. The surface material should be able to adapt to printing and printing, have good ink-retaining properties, and have sufficient strength to accept various processing, such as die cutting, waste discharge, slitting, punching and labeling.
3. Coat the bottom
It is the same as the surface coating, except that it is coated on the back of the face material. The main purpose of coating the bottom layer is:
(1) Protect the surface material from adhesive penetration.
(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, which affects the performance of the adhesive, resulting in the reduction of 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 plays a role in connection. According to its characteristics, it can be divided into two types: permanent and removable. It has a variety of formulas, suitable for different face materials and different occasions. Adhesive is the most important component in the technology of self-adhesive materials and the key to the application technology of labels.
5. Release coating (coating silicon layer) is to apply a layer of silicone oil on the surface of the base paper. Applying silicone oil can make the base paper a very low surface tension, very smooth surface, the role is to prevent the adhesive from sticking to the base paper on.
6. Backing paper
The role of the backing paper is to accept the release agent coating, protect the adhesive on the back of the face material, and support the face material so that it can be die-cut, waste discharged and labeled on the labeling machine.
7. Back coating or back printing
Back coating is a kind of protective coating on the back of the backing paper to prevent waste discharge. The adhesive around the rewinded label adheres to the backing paper. Another role is to make multilayer labels. The function of back printing is to print the registered trademark or pattern of the manufacturer on the back of the backing paper, which plays the role of publicity and anti-counterfeiting.
[next]
There are five types of stickers:
According to the characteristics of the adhesive, it can be divided into permanent adhesive materials and removable adhesive materials;
Classified by adhesive coating technology, it can be divided into hot melt adhesive materials, solvent adhesive materials and emulsion adhesive materials; (not very understandable)
According to the classification of adhesive and chemical characteristics, it is divided into two types of rubber-based and acrylic stickers;
According to the characteristics of the base paper, it is divided into three types of self-adhesive materials: opaque base paper, translucent base paper and transparent base paper;
According to the characteristics of surface materials, it is divided into paper stickers, film stickers and special stickers.
[next]
Finally, we will talk about the specific printing and processing technology of self-adhesive film material labels according to the classification of face materials:
1. Printing and processing technology of paper stickers
1. Printing process flow
Different types of materials, different uses of labels, the process used is also different. Generally label printing machine is a multi-function device, and the processing plant can formulate printing process according to the requirements of customers. The printing and processing technological process of the sticker is as follows:
(1) Unwinding
A Intermittent: No tension changes when the roll paper is unwound, so no adjustment is required. It is applied to flattening and rounding flat labeling machines, and the unwinding speed is slow. Because such equipment does not have a paper positioning correction device, the end surface of the roll paper is required to be clean and tidy to ensure accurate overprinting during printing.
B continuous type: It is applied to the round and round labeling machine. As the roll paper diameter and speed change, the paper tension changes, so this device has a tension automatic or manual control mechanism, as well as roll paper correction correction device to ensure smooth paper feed and print quality.
(2) Bronzing
Flattening and flattening: It is applied to round flattening and flattening and labeling machines with low speed.
Round pressing: applied to round pressing label printing machine, fast speed, continuous bronzing, generally seldom used, generally use gold printing process instead of bronzing.
(3) Printing
Flat pressing: suitable for printing small areas and simple patterns, such as price labels, bar codes, etc.
Round flattening: suitable for label printing with solid patterns on the ground, and simple color mesh printing.
Round pressing is suitable for all kinds of pattern label printing, especially for high-end color mesh label printing.
UV printing: In the above three printing methods, after UV drying, all film stickers can be printed.
(4) Bronzing first, then printing
On the equipment without UV drying, the use of ordinary ink, the disadvantage is that the design of the printed pattern is limited.
(5) Print first, then bronzing
It is applied to the equipment with UV drying device. After the ink is dried quickly, it can be gilded on the ink, and the gilding pattern can be arbitrarily designed, not limited by the ink.
(6) Glazing
Field polishing: coat a layer of varnish on the ink surface, the purpose is to protect the ink layer, prevent moisture, waterproof and improve the surface gloss, can replace the laminating process, using UV drying method.
(7) Laminating
Laminating on paper or film material, the purpose is to protect the ink, waterproof, moisture-proof, increase the label strength, increase the pattern
Three-dimensional. The laminating film is divided into a laminated film with a bottom paper and a laminated film without a bottom paper. Due to the low cost of the latter, it is currently widely used. According to the requirements of the process, there are two kinds of composite transparent film and matte film, the former is more commonly used.
(8) Punch
The application is not common, mainly used for computer-printed labels. The requirement is that the positioning drive holes are drilled on both sides of the label, or the label applied on the price tag gun is required to be punched in the middle of the label for positioning and driving.
(9) Die cutting
The die-cutting of self-adhesive labels is a half-cut process, that is, only cut through the surface material and retain the bottom paper. Divided into two processing methods:
Such as flat die cutting, suitable for all kinds of label printing machines, manual plate making, low cost, short plate making cycle, but low viscosity, suitable for short version live printing processing. At present, almost all domestic label factories adopt flat die cutting. The other is round die cutting, which is applied to round pressure round label equipment. It has fast speed and high die cutting viscosity, which is suitable for long plate work. The disadvantage is that the plate making cost is large and the cycle is long. At present, the die-cutting rolls of domestic manufacturers are generally processed abroad.
(10) Paper collection
It can be roughly divided into cut sheet paper collection and folding paper collection.
2. Processing method of paper stickers
(1) Sheet paper
Among the printing methods of such self-adhesive materials, offset printing accounts for 95%, relief printing accounts for 2%, screen printing accounts for 2%, and computer and printing accounts for 1%. The printing of self-adhesive labels on single sheets of paper is the same as ordinary printed products. Each process is completed on a single machine. The production efficiency is low, the cost is high, and the printing quality is good. If the offset printing process is used, the quality of the four-color printed label is much better than the similar products printed by the label printing machine. However, because the form of the self-adhesive finished product printed on a sheet of paper is a sheet of paper and cannot be rewound, such products can only be labeled manually, and cannot be automatically labeled on an automatic labeling machine. Single-sheet printing is suitable for large-area sticker color prints. Such as posters, posters, large-area labels, etc., are not limited to label products. It can be said that sheet-fed sticker printing is an important part of the sticker printing industry.
(2) Roll paper
Among the printing methods for web-based adhesive materials, relief printing currently accounts for 97%, screen printing accounts for 1%, offset printing accounts for 1%, and flexographic printing accounts for 1%.
Due to the web printing process, all the 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 our country is in the form of letterpress printing and has few functions. It is only suitable for printing labels with simple color blocks and line patterns, and the printing quality is not as good as that of single-sheet offset printing. However, labels processed on roll paper can be rewound into rolls, which can be applied to automatic labeling machines, bar code printers, electronic scales and other equipment, which is convenient for automated production. Web-printed stickers are the mainstream of sticker printing in the world.
[next]
Second, the printing process of film stickers
Compared with ordinary paper, film materials have many advantages, and film material printing is the direction of self-adhesive printing in the future. We briefly introduce the structural characteristics of thin film materials, printability and post-press processing technology:
1. Structure and characteristics of thin film materials
(1) Structure
The film material has the same structure as the paper material, the only difference is that the surface of the material needs to be treated.
(2) Surface characteristics and treatment methods
The principle that the ink layer forms a pattern on the printed matter is penetration, volatilization, film formation, and curing. Due to the high film density, the ink is only volatile and conjunctival. There is no penetration during the curing process, so 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 material. The surface treatment usually has the following methods:
A corona treatment: Discharge the surface of the film by high voltage charge, and finally achieve the purpose of increasing surface energy, that is, surface tension. Corona treatment is generally carried out in the film manufacturing plant, because the surface tension is time-limited, it requires strict testing before printing. Therefore, some advanced equipment has a pre-press corona treatment device in order to print high-quality film products.
B printing process: chemically changing the surface characteristics of the film to make it suitable for ink printing or ribbon printing.
C surface coating: use chemical substances to coat the surface of the film, increase the surface tension, and change the surface characteristics.
2. The printing process of thin film materials
(1) Printing process of thin film materials
The basic printing methods are gravure printing: divided into gravure solvent ink printing and gravure printing water-based ink printing; offset printing: UV offset printing ink printing; relief printing: divided into ordinary resin ink printing and UV relief printing ink printing; flexo printing: divided into water-based printing Ink printing, solvent ink printing and UV ink printing; silk screen printing: divided into UV ink printing and solvent ink printing; combination printing: divided into relief printing + silk printing, relief printing + flexo printing, flexo printing + silk printing, offset printing + relief printing Printing method. Here are some more specific printing methods:
A. Ordinary resin ink printing. This is currently the most commonly used method. Due to the drying problem, there are two methods of drying treatment: cutting single sheets and drying on the shelf. This method takes a long time to dry, covers a large area, and is easy to get dirty.
Laminating. Wrap the undried ink between the films, pay attention to avoid publishing the film, and prevent the film from failing.
B. UV ink relief printing. This method has good printing quality and high efficiency. It is the most developed printing process in China and most suitable for national conditions. Because domestic embossing equipment generally does not have a UV device, film printing is limited, so equipment renewal and transformation is a necessary condition for printing films.
C. Solvent ink flexo printing.
This is a traditional printing method with good quality. Due to the low surface tension of the solvent ink, the film surface tension requirements are not as strict as other inks, so the ink layer is strong and the process is relatively simple. However, the solvent affects the environment and is harmful to the human body, which is a printing method to be eliminated.
D, water-based ink flexo. This is the most advanced printing method in the world today, with low cost, good quality and no pollution. But the process requirements are strict, the film surface tension must be above 40 dynes, and there are strict requirements on the PH value and viscosity of the ink. This process is a process vigorously developed in China, but it has been developed slowly due to equipment limitations.
E. UV ink flexo printing. The features are the same as UV embossing, and the cost is high, but the film surface tension is relatively less strict. Generally, most manufacturers use water-based ink to print, and UV glazing can reduce the cost and increase the printing effect.
F. UV ink screen printing. This new process can be printed on a single sheet or web, with high cost and good quality. Single sheet printing does not need to be put on the shelf to dry, roll printing can be carried out at high speed.
G. Solvent ink screen printing. This is a traditional process. Generally, the single sheet is printed by hand, and the roll material is printed by a linkage. More than 95% is single-sheet printing, with good effect and low cost. However, solvent screen printing inks are harmful to humans and pollute the environment.
H. UV offset printing ink. Since resin ink is used for glue, ordinary offset printing cannot print films. Some manufacturers use single-sheet overprinting when printing PVC, drying on shelves, and finally laminating. However, because the ink is not easy to dry and easily smeared, it causes waste and low productivity. With UV offset printing, all of the above problems are avoided, and high-level layered film products can be printed.
I. Gravure printing. Gravure printing rarely prints stickers, but the printing quality is the best of all printing methods and is a potential printing method. As long as the post-press processing is solved in China, the existing equipment can print high-quality self-adhesive labels.
J. Combined printing, also called compound printing, is the most advanced printing method in the world's packaging and printing industry. According to different pattern designs, several methods are used to print on the same pattern to achieve the best visual effect. This kind of equipment is very common abroad. There are two types in China: LINTEC's SR-520B in Japan and SHIKY's F-330. The former is embossed + silk screen, the latter is offset + embossed.
(2) Ink drying method
The inks on the film are divided into drying characteristics: oxidative polymerization drying (tree finger ink), volatile conjunctival drying (solvent ink), evaporative conjunctival drying (water-based ink) and photocuring drying (UV ink).
Drying methods are divided into: hot air drying, electric heating drying (far infrared), ultraviolet curing drying.
Requirements for drying: the ink is fully dried; it does not affect the physical and chemical characteristics of the film; it does not affect the characteristics of the adhesive; it has no effect on the base paper.
Methods to improve the drying effect of ink:
A. Use additives to improve the drying speed of the ink. Such as resin ink plus dry oil; water-based ink plus special additives, solvent ink plus low boiling point solvent. However, it should be noted that additives will change the brightness and brightness of the ink, and the bonding strength between the ink and the film cannot be affected by the additives.
B. Change the operating speed of the film material.
C. Change the temperature in the drying oven or change the intensity of the ultraviolet light source.
D. Choose appropriate film materials.
(3) Post-press processing technology
The post-printing process of film materials is almost the same as the post-printing process of paper labels. Such as bronzing, laminating, punching, folding, cutting, rewinding, waste disposal, die cutting, etc. are all used for post-print processing of film stickers.
It is unscented and breathable. Good breathability makes you free breathing when wear it.
It is Disposable, it makes you more convenient.
It is Fashionable and very beautiful, keep you in fashion.
It is Washable, you can reuse it for several times after washing.
It is much more Softer and Skin-friendly than common PITTA mask, make you more comfortable when using it.
Higher density make it have more intensive porosity. make it more efficiently protect you from particles as dust, fog, haze, and pollen etc. It also can help to reduce transmission of flu virus, to a certain degree.
Good air permeability of it, make you easy breath when wearing it.
Mask Sponge,Safety Mask Sponge,Anti Pollution Mask Sponge,Safety Air Pollution Mask
FengRun Commodity Co.,Ltd. , https://www.sponges.nl