Packaging and printing industry, in addition to using UV curing technology to reduce emissions of VOCs, solvent-free composite technology is also an important technology. Packaging and printing industry products can not be separated from the use of organic solvents, which means that there will be a large number of VOCs emissions. Solvent-free composite technology solvent-free adhesives instead of solvent-based adhesives, VOCs emissions can be avoided from the source.
Solvent-free composite technology is what?
At present, the three most important environmental protection technologies of international flexible packaging are solvent-free composite technology, flexographic printing and co-extrusion compounding. Among them, solvent-free composite technology is the most environmentally friendly and was also selected into the 2016 National Advanced Pollution Prevention and Treatment Technology Catalog VOCs prevention and control) ". Solvent-free composites are relatively traditional dry-solvent-based composites and are another composite process used in the flexible packaging industry. Solvent-free composite solvent-free adhesive, the film-like substrate (plastic film or other film-like material) bonded to each other, the curing (adhesive chemical reaction) so that the layers of substrate firmly together, Thereby producing a multi-layer composite film processing method.
Solventless compound machine
What are the advantages of solvent-free composite technology?
Solvent-free composite with the traditional dry composite contrast, the advantages are mainly reflected in the following aspects:
save resources
No solvent is used, solvent cost is saved; no drying process can save a lot of energy; less sizing agent and solvent-free composite adhesive coating weight per unit area is about the dry basis weight of the adhesive 2/5).
Safety and environmental protection
Solvent-free composite adhesive is one hundred percent glue, does not contain any solvent, so in the production process, in addition to downtime need to use a small amount of solvent on the glue part of the cleaning, no solvents and VOCs and other pollutants emissions, No pollution to the health of production workers and the surrounding environment; no combustible, explosive organic solvents are used in the solvent-free compound production, so the safety is good; the hygienic performance will not decrease in the composite film due to the presence of residual solvents, Product health performance and reliability.
Reduce costs
Solvent-free composite process per unit area less glue, plastic materials, low cost, and a one-time investment, equipment recovery depreciation costs are relatively small. In the compounding process, the solvent in the adhesive is not required to be removed by the bake heating, and each solvent-free compound production line consumes much less energy than the dry-process compound line (about 1/20 of the 1000 process compound line ); Solvent-free compound production line significantly increased speed, which can reduce production costs. Solvent-free compound of the highest line speed of up to 600m / min or more, generally also at about 200m / min; solvent-free compound without waste generation, without the need to configure expensive environmental protection equipment and the corresponding operating costs.
Solvent-free composite technology should pay attention to what?
Determine the components of the solventless adhesive
Two-component solvent-free adhesive component A (containing -NCO) is easy to react with water, affecting the ratio of adhesive, thus affecting the quality of the product compound, so the solvent-free composite process of water vapor particularly demanding requirements of operating workshops, The lower the relative humidity of the adhesive repository, the better the drying and filtering of the gluing system must be thorough.
One-component, solvent-free adhesives are the more economical option for paper / aluminum, paper / plastic composites, or simple white film composites with a large amount of glue. However, the one-component solventless adhesive requires moisture to be used in the curing process, and the moisture needs to be added online to ensure that the composite product is cured. This compound approach is subject to certain restrictions in the north, especially in dry winter applications, requiring special attention.
Make a sample test
Today, each flexible packaging company has its own unique product and technical characteristics, each company uses raw materials are not the same, even within the enterprise, different products used in the substrate, ink, solvents vary in variety, and Solvent-free adhesives are different from the traditional solvent-based adhesives, the molecular weight is generally low, vulnerable to changes in external factors. Therefore, before each product is used for the first time in the production of solvent-free composite process, it is recommended to carry out the compound test of the sample first, and then put into batch production after passing through the identification of the compound sample.
Pay attention to the individual differences of special products
Because solvent-free adhesives have low molecular weight and strong penetration, some products do not present problems with traditional solvent-based composites, but special attention is required if solvent-free composites are used. For example, in the case of a flexible packaging product with a thinner composite substrate and addition of a large amount of aids (especially inorganic pigments such as titanium dioxide, etc.), the conventional compounding process does not cause any major quality problems, but the solvent- When the process, if the choice of adhesive molecular weight is low, and the amount of glue is too large, the adhesive will be through the substrate, severe heat accumulation in the substrate surface, through the second reaction, the formation of urea and other derivatives, the impact Product heat sealing quality. In addition, because solvent-free adhesives are more permeable than solvent-based adhesives, for some flexible packaging products that require printing, the use of a solvent-free compound process can result in a product that differs in hue from the solvent-based compound; and because Solvent adhesives are highly permeable, and the edges of the printed designs in the composite become larger, while the strokes in smaller text are more coarser.
Vision expansion
At present, there are mainly manufacturers of solvent-free composite equipment in the world: W & H in Germany, Nordmecanica in Italy, Schiavi, Bielloni in Italy, DCM in France and Comexi in Spain. Many of our composite equipment manufacturers have also invested in the development and research of such equipment and have made some progress. In 1985, Beijing Institute of Chemical Industry introduced the first solvent-free coated composite testing machine made by DCM Company, engaged in scientific research and production. Then in 1996, Tianjin Topheng Printing and Packaging Company from Italy Schiavi
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