The structure of the self-adhesive material is composed of three parts on the surface, namely the surface material, the adhesive, and the bottom paper, but from the perspective of the manufacturing process and quality assurance, the self-adhesive material is composed of seven parts: surface coating, Surface materials, bottom coating, adhesives, backing paper, and back coating or back printing.
The so-called surface material refers to the surface material, which is the material that accepts printed graphics and text on the front and the adhesive on the back and is finally applied to the object to be pasted. 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 properties, and have enough strength to accept various processing, such as die-cutting, waste discharge, slitting, punching, and labeling. The surface gloss and color consistency and density uniformity index of the surface material determine the uniformity of ink absorption of the adhesive material and also determine the color difference of the same batch of label printing products.
Self-adhesive labels can be divided into two categories: paper and film based on the surface area.
Common surface materials and characteristics are as follows.
(1) Offset paper: also known as writing paper or molded paper. The surface is uncoated matt paper. Generally, monochrome printing or printing, bar code information labels, and direct writing can also be used.
(2) Coated paper: it is coated paper. The surface of the face paper is coated with medium gloss paper. It has high flatness and lower surface brightness than mirror coated paper. It is currently used in the pharmaceutical industry and food industry under color printing. Good printing material for transferring barcode labels.
(3) Mirror coated paper: * grade calendering treatment, high surface gloss, used for product labels that require bright printing colors. Industries such as medicines and health products.
(4) Thermal paper: The most common ones are * municipal information labels, which are also currently used in thermal printing information labels for large logistics companies.
(5) Thermal transfer paper: a self-adhesive label material specially developed for thermal transfer printing. The surface of the face paper is treated with a special coating, especially for small barcodes. It has an excellent printing effect so that it will not be affected when scanning product barcodes. The broken point and broken line of the barcode can not be recognized, and the surface paper is not easy to change color, and the durability is longer than that of coated paper.
(6) Laser printing paper for office use: Offset paper is the most common material for laser printers in the market, but the high temperature and high speed of the printer make the pressure-sensitive adhesive easy to cause glue leakage failure under the action of high temperature, and it is easy to damage the printer. Special laser printing paper stickers can solve this problem. There are also some uncommon paper self-adhesive label surface materials, such as fragile paper, aluminum foil, etc., which are also used in food, health care products, and wine products.
(7) PE film: Polyethylene film, with bright white, sub-white, bright silver, and transparent on the surface. It is soft and has the characteristics of water resistance, oil resistance, and extrusion resistance. It should be widely used in daily chemical products, such as Shampoo, shower gel, and other products.
(8) PP film: polypropylene film, with bright white, sub-white, bright silver, and transparent surfaces, and has the characteristics of water resistance, oil resistance, and good stiffness. *The transparent PP self-adhesive label material, due to its high transparency, is attached to the transparent bottle body, which looks like a non-label visual effect. It is also widely used in daily chemical products and cosmetics.
(9) PET film: Polyester film, which can be divided into treated and untreated surfaces. The surface has bright white, sub-white, transparent and various kinds of bright silver and sub-silver after metallization treatment. Because of its high stiffness, it has the characteristics of water resistance, temperature resistance, oil resistance, and solvent resistance. It is suitable for labeling materials for various electronic products and machinery on flat surfaces.
(10) PVC film: polyvinyl chloride film, the surface is transparent, white, sub-white, and has the characteristics of water resistance, oil resistance, and solvent resistance. It is mainly used in chemical products. PVC film with shrinkage properties can be used as a material for battery shrink labels.
The adhesive is the medium between the label material and the bonding substrate, which acts as a link. According to its characteristics, it can be divided into two types: permanent and removable. It has a variety of formulas, suitable for different surface materials and different occasions. The adhesive is the most important component in the adhesive material technology and the key to label application technology.
According to the source of the material
1. Natural adhesive
It is taken from the matter in nature. Including starch, protein, dextrin, animal glue, shellac, leather glue, rosin, and other biological adhesives; also including asphalt and other mineral adhesives.
2. Artificial adhesive
These are artificially manufactured substances, including inorganic adhesives such as water glass, and organic adhesives such as synthetic resin and synthetic rubber.
According to raw materials
1. MS modified silane
The modified silane polymer ends with methoxy silane, which is the only supplier of modified silane raw materials in the world. On this basis, it has produced a series of high-quality sealants and sealants used in construction, industry, automobile transportation, and civil use. Adhesive.
The full name of polyurethane is polyurethane, which is a general term for macromolecular compounds containing repeating carbamate groups on the main chain. It is formed by additional polymerization of organic diisocyanate or polyisocyanate and dihydroxy or polyhydroxy compound.
Silicones are commonly known as silicone oil or dimethyl silicone oil, molecular formula: (Ch3) 3SiO (Ch3) 2SiOnSi (Ch3) 3, a polymer of organosilicon oxide, a series of polydimethylsiloxanes with different molecular weights, The viscosity increases with the increase of molecular weight.
According to the characteristics of use
1. Water-soluble adhesive
Adhesives that use water as a solvent mainly include starch, dextrin, polyvinyl alcohol, carboxymethyl cellulose, etc.
2. Hot melt adhesive
It is a solid adhesive for use after melting the adhesive by heating. General thermoplastic resins can be used, such as polyurethane, polystyrene, polyacrylate, ethylene-vinyl acetate copolymer, etc.
3. Solvent-based adhesive
A binder that is insoluble in water but soluble in certain solvents. Such as shellac, butyl rubber, etc.
4. Emulsion adhesive
Most are suspended in water, such as vinyl acetate resin, acrylic resin, chlorinated rubber, etc.
5. Solvent-free liquid adhesive
It is a viscous liquid at room temperature, such as epoxy resin, etc.; solvent-based and hot-melt adhesives that pollute the environment are developing into water-soluble emulsion adhesives that do not pollute the environment.
According to packaging materials
1. Paper-based material adhesive
Mainly include starch paste, dextrin, water glass, chemical paste, casein, etc.
2. Plastic adhesive
Mainly include solvent-based adhesives such as styrene-butadiene rubber, polyurethane, nitrocellulose, polyvinyl acetate; water-soluble adhesives such as ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer; emulsion type such as vinyl acetate resin and acrylic resin Adhesives; hot melt adhesives composed of thermoplastic resins such as polystyrene, polyurethane, polyacrylate, etc.
3. Wood adhesive
It mainly includes animal glues such as bone glue, skin glue, shellfish glue, casein, blood glue; synthetic resin glues such as phenolic resin glue, polyvinyl acetate resin glue, urea-formaldehyde resin glue, and vegetable glues such as bean glue.
Adhesives and adhesives are the general terms for non-metallic materials that can combine a solid surface with another solid surface due to surface bonding and internal forces (adhesion and cohesion, etc.).
End of the paper
The function 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, discharged and labeled on the labeling machine. Like the face material, the uniformity and strength of the backing paper are not only related to the printing performance, but also an important indicator that determines the uniformity of die-cutting, the speed of the waste discharge, and the edge fracture.
1. Super calendered bottom paper.
For high-grade kraft paper, the smooth surface after super calendering can be coated with silicon evenly and with the least amount of silicon; high tightness can increase the strength of the bottom paper so that the best die-cutting effect can be obtained with the least pressure during die-cutting. Super calendered bottom paper, uniform thickness, belongs to translucent bottom paper, suitable for high-speed die-cutting and automatic labeling of webs. The disadvantage is that it is sensitive to environmental humidity, poor dimensional stability, and is not suitable for cutting into single sheets.
2. Machining calendered bottom paper.
The middle-grade kraft paper has a coating on the surface. After the ordinary calendering process, the surface is smooth and compact and can be coated with silicone oil. The machine-processed calendered bottom paper has a certain thickness and is an opaque bottom paper. The biggest advantage is that the surface is flat, the dimensional stability is good, and the back printing is possible, which is suitable for single-sheet printing and printing.
3. The surface is coated with plastic bottom paper.
The kraft paper is coated with a layer or before the silicon is applied to increase the smoothness of the surface, reduce the coating amount of silicone oil and increase the strength and dimensional stability of the bottom paper. Plastic-coated bottom paper has low cost and high strength. It is suitable for web printing and sheet-fed printing. It can be printed on the back and is currently the most used bottom paper.
4. Plastic film bottom paper.
The characteristics are: the surface is flat and smooth, waterproof, strong, and transparent. After the transfer of the glue layer, it becomes a smooth mirror layer, which is especially suitable for high-speed labeling, and there will be no breakage of the bottom paper. The disadvantage is that it is expensive, sensitive to temperature and tension, and cannot be printed.