From the lamination of materials, the fixation of core layer, to the composite of different components, hot melt adhesive has a wide range of applications in sanitary products, and plays an important role in the overall structure and function of sanitary products. At the same time, hot melt adhesive does not play a role alone, only the hot melt adhesive, substrate and production equipment and technology closely combined, in order to produce qualified products.

First, what is hot melt adhesive

Hot melt adhesives are thermoplastic continuants, solid at room temperature, but liquefied at higher temperatures. When heated to a certain temperature, it is fused into a viscous liquid. The molten liquid is coated with a warm substrate, pressed together, and cooled to room temperature. In a few seconds, the adhesive is completed, that is, the adhesive is formed. Representative melting temperature is 65℃~180℃. As it is 100% solid without any solvents, it meets the strictest air pollution control requirements and poses little risk of fire or explosion. In addition, hot melt adhesive has the following advantages for users:

1) Fast curing speed reduces the amount of compression required for gluing, so the production speed can be improved and the equipment space can be saved

2) It can then be applied to hydrophobic surfaces without the need to use wet dissolving agent. Therefore, it has water resistance and excellent storage stability

3) Because 100% solid parts are completely available, there is less waste, which can reduce transportation and storage costs

4) Can be followed by a wide range of substrate, can be automated

Two, characteristics and uses

Hot melt adhesive has a wide range of uses and can become an economical material if matched with equipment and price. The packaging industry accounts for more than 50% of the hot melt adhesive application market. These packaging materials include pleated cardboard boxes, corrugated boxes, laminated material cans, tape, and other laminated coating materials. Non-woven fabrics include sanitary napkins, paper diapers, clothing fitting, sewing and so on. Woven products include ready-to-wear, stitching, tape and carpet backing. Office supplies include tape, documents, self-adhesive labels, and file folders. The parts mix includes soda, electronics, book packaging, furniture, shoes, handicrafts, carpentry, plywood, etc.

Three, hot melt adhesive in the use and application should pay attention to the matter

Because of the wide range of application of hot melt adhesive, its pollution-free, pollution-free characteristics, but also make it in the replacement of solvent type, then, has a great advantage. However, due to the limitation of its characteristics, special attention should be paid to its application, and several items are listed here.

1) Viscosity

Melt viscosity is an important indicator of operability, because the use of hot melt adhesive must rely on the heater, that is, coating machine. Generally speaking, different industries, different uses, different properties, different coating machines, coating methods, determine its melting viscosity. In this should be noted from the use of the same purpose, but because of different manufacturers of coating machines and methods, the viscosity of the cooked sol is also different.

2) Curing time and opening time

Hot melt adhesive using heat as the medium, the colloid cooling immediately after completion, so the use of must pay attention to the operation time control.

setting time: refers to the best short time after coating to form subsequent;

open time: refers to the longest permissible time from coating to pressing;

3) Temperature resistance

Due to the physical properties of EVA, the heat resistance of hot melt adhesive is between 40℃ and 65℃ under constant temperature. The main thing is that the melting point of EVA is also between 40℃ and 70℃. The heat resistance of TPR itself is better, but plasticizer is often added to reduce its heat resistance.

4) According to sex

Talking about continuity, the main focus is to be the material, according to the general classification of metal, plastic, paper, wood, etc., or according to the requirements of customers, choose the appropriate model, appropriate products, can avoid later problems, save service time.

Four, the smell of hot melt glue

1. Which industry customers to hot melt adhesive smell requirements

1) EPE packaging industry

2) Sanitary products industry: In recent years, infant diapers, sanitary napkins, adult care pads and other sanitary products industry has put forward extremely high requirements on the smell of hot melt adhesive, that is, hot melt adhesive should have no smell. With the development of economy and the improvement of people's living standards, there are higher requirements for product quality. In addition, China has only one child in a family due to decades of one-child policy, everyone wants their children to enjoy the best care. Even for baby diapers, they also want children to use the safest and most comfortable products. Therefore, in order to meet the requirements of end customers, sanitary products manufacturers require raw materials without odor, which is also reasonable things.

3) Food packaging industry

4) Automotive interior industry

2. The source of odor

The smell of hot melt glue comes from hot melt glue itself, is the essential characteristic of hot melt glue, affected by raw materials, production process and circulation link. Hot melt collagen materials include main resin, viscosifying resin, diluent or softening oil, enhancer and other components. The inherent smell of raw materials is an important source of the smell of hot melt adhesive. For example, most EVA has a slight acetic acid flavor, while synthetic rubber also has its own flavor, but it is only thick and light. And C9C5 resin has a different taste, even all hydrogenated resin, also has its own taste, but our sense of smell may not be able to detect it, other raw materials also have more smell, but different intensity. In the production process, hot melt adhesive may also have new odor sources, which can be reduced by controlling the production process. In addition, hot melt glue logistics transportation, may also be dyed into the new smell.

Everything has a certain smell, body odor, and there is no such thing as an absolutely odorless substance, and when we talk about odorless, we usually mean that the smell is so weak that it is not felt or negligible. Smell is not equivalent to volatile gas, but it is closely related to volatile gas. The relationship between volatile gases and odors is still a subject. People have habitual adaptations to smells and have different preferences.