What causes the hot melt adhesive to become viscous?

Disposable hygiene products are coated with hot melt pressure sensitive adhesive (referred to as hot melt adhesive) on PE film, non-woven fabric and some elastic materials (mainly elastic rubber) by bonding, embossing, cutting and packaging technology to manufacture the disposable hygiene products.

Defoaming of hot melt adhesive for disposable hygiene products

Gluing process, substrate, environment, operators and other aspects are also one of the factors leading to the loss of viscosity of hot melt adhesives for sanitary products. When applying hygienic hot melt adhesives, it is mainly used in combination with two machine systems. The system is a heating coating system consisting of a hot melt glue cylinder, a throat pipe and a pipe head. The function is to melt the hot melt glue into a liquid state and transport it to the nozzle head of each station and apply it to each material. The other is a rack-based assembly system for the entire disposable hygiene product, in which each material coated with glue is bonded in a process sequence.

Disposable hygiene product gluing process

The disposable gauze sizing process is divided into squeegee coating and spraying. These two coating methods have a range of requirements for the viscosity of the hot melt adhesive, that is, the fluidity index. The heating temperature control system affects the fluidity of the glue. The change of the fluidity of the glue affects the effect of the coating pattern of the glue. The effect of the coating pattern determines the bonding strength of the hot melt adhesive. If the temperature of the glue in the spraying is too high or too low, the glue type may be confused, and the unevenness of the coating may cause the stickiness. In addition to the problem of heating the temperature control system, the blockage of the nozzle of the nozzle can also cause problems.

Substrate

The weight and temperature of the hot-melt adhesive coated substrate of sanitary products need to be adjusted to prevent the occurrence of stickiness. When the substrate is used, the temperature of the substrate affects the open time of the hot melt adhesive of the sanitary article. (Opening time refers to the maximum time that the glue can be bonded to the second substrate after being coated on the first substrate, which is the maximum effective time for the glue to have the bonding strength.) In winter, it is too cold to be pulled out of the warehouse by direct use. The substrate is easy to cause the glue to dry quickly and lose its viscosity.

Operating

Temperature and humidity, dust treatment, workshop hygiene and operator standardization can all affect the bonding strength of hygienic products. Hot melt adhesives need to open the rubber cylinder during the process of adding glue (high temperature operation), so the entry of external environmental impurities can easily lead to carbonization and loss of viscosity.

Whether the amount of glue added by the operator is sufficient, and whether the frequency is stable becomes a key factor affecting the bonding of hot-melt adhesives for sanitary products. The amount of hot melt adhesive is less, and the amount of glue supplied in time is also small, and it is prone to empty glue and cold glue coating, resulting in the loss of stickiness of hot melt adhesive. The level of glue used by the operator itself is a more important factor affecting the bonding of hot melt adhesives. It is estimated that the amount of hot melt adhesive is used, and the temperature parameter setting can be adjusted according to the weather change, and the machine can be maintained regularly. At the time of production, the setting of the machine speed and the design of the composite distance require a suitable opening time of the hot melt adhesive.

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