To analyze the advantages and problems of solvent-free adhesives.

1. Environmental protection
solvent-free compound using solvent-free adhesive, neither volatile VOCs, nor produce any irritating odor, while solving the problem of solvent residues in packaging, eliminating the erosion of organic solvents on printing inks, but also to achieve cleaner production, conducive to environmental protection.
2. Energy saving
solvent-free composite equipment does not need to bake, reducing energy consumption. And in the later maturation process, the temperature of solvent-free compound is basically the same as that of dry compound, so energy consumption is also relatively close to

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3. Safety
Because solvent-free adhesives do not contain organic solvents, there is no risk of fire, explosion in the production, transportation, storage and use process, no explosion and heating measures, no need to be dedicated to the storage of solvents in the repository, more importantly, the health of operators is not harmful.
4. High-efficiency
the speed of using solvent-free adhesive composite is generally 250 to 350 m/min, up to 400 to 500 m/min, while the speed of using solvent-based adhesive composite is generally 150 to 180 m/min, and the speed of water-based adhesive compounding is even lower.
5. Low-cost
if calculated at 20,000 tons per year of solvent-free adhesive use, the amount converted into solvent-based adhesive is 20,000÷1.5×2.5 . 33333 tons (1.5g/m2 for solvent-free adhesives, 2.5g/m2 for solvent-based adhesives on average), it can be seen that the use of solvent-free composite process can greatly reduce the amount of adhesive. In addition, the cost of coating per unit area is 0.026 to 0.052 yuan, the cost of coating per unit area is 0.052 to 0.104 yuan per unit area, and the coating cost per unit area is 0.076 to 0.090 yuan.
the existence of general-purpose solvent-free adhesives
At present, there are several problems with general-purpose solvent-free adhesives for soft packaging composites.
(1) has a large effect on pe film smoothness
when the solvent-free compound maturation temperature is greater than 40 degrees C, the solvent-free composite film with a inner layer of PE film (especially the PE film thickness <45 m structure) has a greater impact, prone to a significant increase in friction coefficient. This is mainly due to the higher the ripening temperature, the more intense the molecular movement of the PE film soothing agent, easy to migrate to the adhesive layer and react with it and be consumed, resulting in an increase in the coefficient of friction of the compound film.
(2) aluminum coating transfer
aluminum coating film, especially polyester aluminum coating film (VMPET), in the solvent-free composite process is prone to aluminum transfer, resulting in the composite film peeling strength is insufficient.
(3) dissolves with ink
in the solvent-free compounding process, sometimes the adhesive and ink dissolve phenomenon, especially dye-type ink.
the problem of cooking solvent-free adhesives
At present, the following problems exist in solvent-free adhesives used in cooking packaging.
(1) poor temperature resistance
most cooking packaging requires 40 minutes of cooking at 121 degrees C. This is because the sterilization temperature of many soft packaging enterprises is controlled at 118 to 120 degrees C, so the maximum temperature does not exceed 121 degrees C, the use of 121 degrees C-resistant cooking solvent-free adhesive will not have quality problems. However, some soft packaging enterprises will strictly control the sterilization temperature at 121 degrees C, or in order to ensure product quality even in accordance with the conditions greater than 121 degrees C sterilization, which requires cooking-type solvent-free adhesive can withstand 125 degrees C or higher temperature, in order to ensure that the composite products will not have quality problems.
(2) matching problem with ink
When the steamed solvent-free adhesive is applied to transparent cooking packaging, there is generally no compound film layering. However, when the solvent-free adhesive and ink match is poor, it will cause the peeling strength at the ink is significantly lower than that at transparent and other color inks, and the ink is more prone to layering after cooking.
other composite problems are
. 1. Aluminum foil composite material peeling strength is low
At present, the general film solvent-free compound process, solvent-free adhesive application has been relatively mature, but for aluminum foil solvent-free compound, due to its peeling strength is not enough to meet the requirements of heavy-duty packaging and cooking resistance, is still a bottleneck to be broken.
2. Frequent change of adhesive type
With the development of solvent-free composite process, many adhesive suppliers have introduced general-purpose solvent-free adhesives, cooking solvent-free adhesives, aluminum foil-specific solvent-free adhesives, low coefficient of friction Solvent-free adhesives, although the diversification of products can meet the composite requirements of different materials, but soft packaging enterprises should also be based on different composite materials used in different adhesives and frequent cleaning of adhesive equipment and composite equipment, not only waste time, manpower, financial resources, but also low production efficiency.
trend of solvent-free adhesives is
. 1. Functional solvent-free adhesives
solvent-free adhesives should be developed to functional products, such as research and development resistant to benzene, toluene, xylene, esters, surfactants, content of less than 20% DMF organic solvent mixture, pesticides and other corrosive products.
2.UV-cured solvent-free adhesive
. UV-cured solvent-free adhesive has the characteristics of fast curing speed, product transparency, high peeling strength, good softness of finished glue, but also has the advantages of solvent-free, non-toxic, non-corrosive, energy-saving and environmental protection, can be used in plastics/plastics, plastics/paper, plastic/metal film and other materials of rapid solvent-free composite. At present, UV-cured solvent-free adhesives have been developed, but still need to increase research and development efforts to market more mature products.
3. Solvent-free adhesives for other industries
develop solvent-free adhesives for textile, automotive interior and other industries, as well as solvent-free adhesives for paper (including kraminic, paper jam, plain paper) /plastic (various transparent films, aluminum coatings, aluminum foils).
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