In the manufacture of toddler pants, the existence of hot melt adhesive can not be ignored. However, the application of different adhesives in toddler pants will be different. Although there are various similar materials in the market, it also requires some experience in how to select materials suitable for their own production line. Therefore, a common glue: Styrene Elastomer hot melt adhesive is introduced around this kind of material.
Thermoplastic elastomers are more known as natural rubber. Its duality makes it not only have the characteristics of rubber but also plastic. It has the toughness and elasticity of rubber at room temperature and can be flow formed at high temperature. There are many kinds of thermoplastic elastomers, mainly polyurethane elastomers, polyamide elastomers, etc. As a kind of rubber material, Styrene Elastomer not only has low cost, but also has the advantages of high performance. It is more widely used than other types of thermoplastic elastomer.
SBS and sis are triblock copolymers with incompatible two-phase structure, with hard plastic phase at both ends and soft rubber phase in the middle. Similar to polystyrene, it not only has thermoplastic and solubility, but also has characteristics similar to rubber. Triblock copolymers, such as SBS, associate or crosslink with plastics at room temperature to form a physical crosslinking zone and play a reinforcing role. Thermoplastic elastomer shows the characteristics of vulcanized rubber at room temperature. The reason of plastic flow at high temperature is the cross-linking network structure formed by hard segment and soft segment. The elastic modulus of Pb is three times that of PI. Compared with SBS, SIS not only has multiple methyl side chains, but also has the characteristics of high elasticity and strong adhesion. It is more suitable for preparing hot-melt adhesive for sanitary products.
Due to different synthesis methods, SIS and SBS have different structures. The general star configuration of SBS and sis is greater than the relative molecular weight of linear configuration. The average molecular weight of linear SBS is 80000 ~ 120000, and that of star SBS is 140000 ~ 300000; The average molecular weights of linear is and star sis are 150000 ~ 300000 and 150000 ~ 400000 respectively; High average molecular weight, high crosslinking density and high cohesion. Therefore, the viscosity of SIS and SBS is generally higher than that of linear structure, but the melting viscosity is large and the processing performance is poor.
Viscous resin is usually the general name of a kind of low molecular amorphous thermoplastic polymer. It is formed by monomer with fatty ring structure or monomer polymer that can form ring structure in the process of polymerization. The softening point is 60 ~ 150 ℃. Tackifying resin can improve the wettability of the adhesive to the substrate, make them fully contact and bond, achieve the purpose of improving the adhesive strength, improve the impact resistance and peel strength of the adhesive, prolong the service life, reduce the melt viscosity and creep, and is widely used in adhesive, coating, ink and other industries.
Styrene thermoplastic elastomer is a triblock copolymer with unique soft and hard two-phase structure. In order to make the hot melt adhesive have the best comprehensive properties, the compatibility between the adhesive resin and elastomer must be considered when selecting the adhesive resin. Generally speaking, viscous resins can be divided into three categories; The first type can only be compatible with soft segments. This viscous resin has low solubility parameters and low polarity, mainly including aliphatic petroleum resin, rosin resin, mushroom alkene resin and mushroom alkene phenolic resin with low softening point; The second type can only be compatible with hard segments. This viscous resin has high solubility parameters and high polarity, mainly including various aromatic petroleum resins, ancient Malone wool resin, aromatic modified mushroom ene resin and wool resin; The third kind is compatible with elastomer, mainly including aromatic petroleum resin with low softening point and mushroom olefin phenolic resin with high softening point. Among all tackifying resins, only the first one gives the hot melt adhesive initial viscosity and pressure sensitivity.
In addition to the above main ingredients, there are other ingredients. With the development of decades, this kind of hot melt adhesive has gradually become the market leader, and has been verified in toddler products. However, at present, people's requirements for product quality are higher and higher day by day, and there are still weak links in some technical links of this kind of materials. Therefore, it also needs the unremitting efforts of people in the industry to continuously improve technology and improve material properties.