Hot melt adhesive is a solid adhesive without any solvent, which is made by adding tackifying resin, plasticizer, antioxidant and other additives. It is a fusible polymer with a solid content of 100%, which is in a solid state at room temperature. When heated and melted to a certain extent, it will become a flowing and viscous liquid state. After cooling and curing, it produces adhesive force to the substrate, does not pollute the surface of the substrate, and has a certain re viscosity. Compared with solvent adhesive, water-based adhesive and other adhesives, adhesive has incomparable advantages. It has the advantages of environmental protection, fast coating speed, high degree of automation and low product cost. It is widely used in women's products, medical and health care, tape, packaging and so on. Especially in the diaper industry, it is an indispensable major member in the manufacturing process.
EVA hot melt adhesive is a solid adhesive made of EVA resin, tackifying resin, plasticizer, antioxidant and filler. EVA appeared and began to be used in China. So far, EVA is also the country with the most extensive application and consumption in China. EVA has excellent bonding performance and has a certain thermal bonding force to almost all kinds of materials; It has the characteristics of excellent electrical performance, low melt viscosity and convenient coating construction. At present, it has been widely used in book binding, wood processing, packaging, garment lining, automobile, building materials and other industries. But EVA also has obvious disadvantages: low bonding strength, poor thermal stability, not resistant to fatty oil and not suitable for large-area coating.
Polyester used as hot melt adhesive is a saturated copolymer resin with certain crystallinity and rigidity, mainly because its molecular chain contains a large number of polar groups, such as ester bond and ether bond. Polyester hot melt adhesive has excellent electrical and bonding properties, as well as good heat resistance, cold resistance, water resistance and medium resistance. It is widely used in clothing, automobile, shoes, electronics, packaging, wood processing and other industries. However, due to its high melt viscosity, slow curing speed and easy degradation in storage, the development and application of polyester adhesive will be affected to a certain extent. At present, the main research hotspot of polyester is degradable polyester.
The molecular chain of Pu hot melt adhesive contains - NCO, which can react with various functional groups containing active hydrogen to form interfacial chemical bond, and has strong adhesion to various materials. It is widely used in packaging, construction, wood, book binding, printing and other industries. In addition, polyurethane adhesive has good low temperature resistance, but due to the existence of isocyanate monomer, the adhesive also has great toxicity, which is easy to decompose and produce carbon dioxide, which makes the storage stability of the adhesive poor and easy to produce bubbles. This kind of glue mainly includes thermoplastic and reactivity. After bonding with reactive polyurethane hot melt adhesive, the end NCO can further react with the substrate or environment to further improve the bonding strength and low temperature resistance, which is better than thermoplastic polyurethane.
In addition, there are many kinds not listed. Different types of glue applied to diapers will have different effects on product performance. The most important thing is to analyze specific problems and select suitable materials according to different processes of each enterprise. On this premise, we must first understand the types of glue.
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