Views: 2627 Author: Site Editor Publish Time: 2024-01-22 Origin: Site
It is a composite material that uses paper, film or special materials as the fabric, an adhesive on the back, and a silicon-coated backing paper as the protective paper. It is processed by printing, die-cutting, etc. It later becomes a finished product label.
There are many types, mainly arising from the different compositions of the three components of self-adhesive adhesive, namely: surface material, adhesive (pressure-sensitive adhesive), and substrate (commonly known as silicone oil-coated releasable substrate). Different surface materials , pressure-sensitive adhesive, and substrate can be combined with many self-adhesive label materials.
Non-professional users often only focus on choosing surface materials because they can directly display design and visual effects. In fact, the most important thing about high-quality self-adhesive label materials is the adhesive and substrate hidden under the "face".
After all, before the finished label leaves the factory, the quality of the surface material is easily checked in pre-press, printing and finished product inspection, so that the user loses less; while the adhesive is easily affected by labeling or the usage environment (temperature, humidity, etc.) Affected by the characteristics of different objects to be pasted, there are also different choices of adhesives.
Usually the adhesive problem will be exposed when labeling, or after it has been attached to the object for a period of time, or even after a considerable period of time, causing the greatest loss to the user. Serious glue overflow will damage the printing equipment; low-grade substrate or silicone oil coating Poor coating will also expose usage problems such as cut-through, flying marks, no labels, and paper jams during die-cutting, labeling, and printing, which will also cause greater losses to users.
01 Self-adhesive label material surface material
The most commonly used surface materials for self-adhesive label materials are paper and chemical film. Common surface materials and characteristics are as follows:
(1) Offset paper: Also known as writing paper and molded paper, the surface is uncoated matte paper. It is generally used for single-color printing or printing, and barcode information labels.
(2) Coated paper: Coated paper, a medium-gloss paper that has been coated on the surface, has high flatness, and the surface brightness is lower than that of mirror-coated paper. It is currently used in the pharmaceutical industry and food industry under color printing, and is also used for thermal transfer barcodes. Better printing material for labels.
(3) Cast coated paper: super calendered, with high surface gloss, used for product labels that require bright printing colors. Such as pharmaceuticals, health care products and other industries.
(4) Thermal paper: Commonly used as information labels in supermarkets, it is 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 paper has been specially coated, which has excellent printing effect especially for small barcodes, so that when scanning product barcodes, the barcode will not be broken. Dots and broken lines cannot be identified. Moreover, the tissue paper does not change color easily and its durability is longer than that of coated paper.
(6) Office laser printing paper: The most common laser printer materials in the market use offset paper. However, the high temperature and high speed of the printer make the pressure-sensitive adhesive prone to glue leakage failure under high temperature and easy to damage the printer. However, 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 products, alcoholic products, etc.
(7) PE film: Polyethylene film. The surface is bright white, sub-white, bright silver and transparent. 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, the surface is available in bright white, sub-white, bright silver, and transparent. It has the characteristics of water resistance, oil resistance, and good stiffness. Ultra-transparent PP self-adhesive label material, due to its high transparency, is attached to the transparent bottle body and looks like a label-free visual effect. It is also widely used in daily chemical products and cosmetics and other fields.
(9)PET film: Polyester film, with or without surface treatment. The surface includes bright white, sub-white, transparent and various metallized bright silver, sub-silver, etc. Due to its high stiffness and characteristics such as water resistance, temperature resistance, oil resistance, and solvent resistance, it is suitable for labeling materials for various types of electronic products and machinery that are attached to flat surfaces.
(10)PVC film: Polyvinyl chloride film, with transparent, white, and sub-white surfaces. It is water-resistant, oil-resistant, and solvent-resistant. It is mainly used in chemical products. PVC film with shrinkage properties can be used as a material for battery shrink labels.
02 Adhesives for self-adhesive label materials
Surface materials are printing carriers, each with its own physical and chemical properties. It is not complicated to choose the appropriate surface paper for different end products.
Judging from the performance of adhesives, the adhesives commonly used in self-adhesive label printing can be divided into two categories: permanent adhesives and removable adhesives. (Permanent is generally used in electronic machinery, such as electronic labels, typical: mobile phone battery labels, removable is generally used in food, personal care, etc.)
Different adhesives are suitable for different objects and labeling requirements. For example, glassware requires that the label can be peeled off within a certain period of time after being applied, and the adhesive itself will not cause damage to the glassware itself and leave no adhesive residue. The same is true for stationery products and furniture products. The performance labels on air conditioners and refrigerators used in homes also have similar characteristics. But more often than not, there is no need to tear it off after applying it, and it is permanently attached to the object being attached.
Glues with different properties have different prices and applications. For everyone to make a better choice, let’s introduce the common self-adhesive glues, which are divided into three types: hot melt glue, hydrosol glue (usually called water glue), and oil glue.
Hot melt adhesive is a rubber-based adhesive. It has strong fluidity and viscosity, is suitable for low-temperature labeling (minus 5 to 10 degrees), and is environmentally friendly and non-toxic; the labeling effect is better than that of hydrosol when there is a trace amount of oil or water on the surface of the object to be pasted.
A、Not resistant to high temperatures, can only be used below 70 degrees
B、It is sensitive to temperature during processing. In winter, it will become hard and brittle if the temperature is lower than 15 degrees Celsius when processed and stored.
D、It cannot be affixed to PVC materials in labeling environments that do not require high temperatures, such as food, medicine, supermarket labels, etc.
Hydrosol is an acrylic adhesive. Strong viscosity, most hydrosols are environmentally friendly and non-toxic. At the same time, water-soluble glues have stronger temperature resistance than hot melt glues. Most hydrosols can withstand temperatures below 90 degrees Celsius, and some hydrosols can withstand high temperatures of about 150 degrees. The low-temperature labeling performance is poor. There are slight water stains or oil stains on the label, and it is difficult for the hydrosol to exert its viscosity. This is because the fluidity of the hydrosol is poor. It is used in food, medicine, daily chemical products and some environmentally friendly products. In addition to the characteristics listed in the table for strict industrial product labels, when the self-adhesive label is first pasted, the stickiness of hot melt adhesive is much stronger than that of water glue. However, if it is left for 24 hours, you can Try it and you will find that labels using water glue are far more difficult to peel off than hot melt glue. This is because the water glue flows slowly. Within more than 20 hours after labeling, the glue under the label finally disappears. Completely adheres to the surface of the adherend.
The difference between oil-based self-adhesive labels and water-based self-adhesive labels is the degree of waterproofing and aging. Oil-based glue itself is not "oil". We generally use soft monomers such as acrylate or vinyl acetate to maintain stickiness after curing. It can be pasted repeatedly and has strong adhesion. Water-based adhesives generally have inferior adhesion, and the adhesive surface may lose tack at high or low temperatures. In fact, in addition to polyvinyl alcohol, water-based glue is also a hydrated emulsion of oil-based glue, but the solvent is changed from MIBK, DBE or butyl acetate to water. It can be used indoors where it does not need to be exposed to humidity. It can be used all day long. Roll-up banners or outdoor photos outside in the wind and rain will not work. Generally, PP paper is made of oil-based glue. In order to increase the bonding fastness with PP, there is also a certain amount of chlorinated polypropylene, that is, CPP, as an adhesion promoter.
Pressure-sensitive adhesives are pressure-sensitive adhesives that can bond two different materials together using only contact pressure. Coat pressure-sensitive adhesive on thin soft substrates such as paper base, cloth base, or plastic to make pressure-sensitive adhesive products such as labels, tapes, and films. Mainly used for coating, protection, metal, plastic, etc. in packaging, offices, vehicles, buildings, etc. The main types and characteristics of pressure-sensitive adhesives on the market are as follows:
(1)Solvent-based adhesive: It is dissolved in solvent, economical, and more adaptable to various use environments, but it is highly toxic to the human body. Its use has been banned in developed countries in Europe and the United States, but it is still widely used in China on wet wipes, sanitary napkins, daily chemical products and even food labels that come into direct contact with the human body;
(2)Emulsion adhesive: soluble in water, environmentally friendly and suitable for most operations;
(3)Hot melt adhesive: preformed adhesive;
(4)UV hot melt adhesive: It is a new technology that can be cured with UV lamps.
Most mid- to high-end self-adhesive label materials use emulsion type and hot melt adhesive as pressure-sensitive adhesive. Different adhesives have different advantages and disadvantages and correspond to different surfaces and environments. Therefore, it is the common interest of printing companies and suppliers to find the most commonly used products. Because a widely used product is easier to produce and has stable high quality, it also saves storage time and space for self-adhesive label material suppliers and printing companies.
If the self-adhesive label is made of the same thickness of glue applied on the same base material, the viscosity will be as follows: oil glue>water glue>hot melt glue, and the price will also be like this. What needs to be noted is that self-adhesive labels are most suitable for label substrates with clean, dry surfaces and no oil or dust. When labeling, the surface of the object to be labeled must be kept dry, oil-free and dust-free, so as to achieve the best labeling effect.
Thank you for your attention.
Attn: Lucy Zhang
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