Use and classification of adhesive for plastic products

There are many kinds of adhesives, which can be divided into many kinds according to composition, use and physical form. Here, the classification and use of adhesives from these three aspects are sorted out, hoping to help you.

01 Classification by composition

1, silicone adhesive

It is a kind of sealing adhesive, with cold resistance, heat resistance, aging resistance, waterproof, moisture-proof, high tensile fatigue strength, small permanent deformation, non-toxic and so on. In recent years, such adhesives have developed rapidly in China, but at present, the raw materials of silicone adhesives in China rely on imports.

2, polyurethane adhesive

It can bond a variety of materials, and can maintain the physical and chemical properties of materials at low or ultra-low temperatures after bonding, mainly used in footwear, packaging, automobiles, magnetic recording materials and other fields.

3, polyacrylic resin

It is mainly used in the production of pressure sensitive adhesives, and is also used in the textile and construction fields.

Adhesive for construction: mainly used for construction decoration, sealing or bonding between structures.

4, hot melt adhesive

According to different raw materials, it can be divided into EVA hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyolefin hot melt adhesive and so on. At present, the main domestic production and use of EVA hot melt adhesive. The main raw materials of polyolefin adhesives are ethylene series, SBS and SIS copolymers.

5, epoxy resin adhesive

It can be used for bonding between metal and most non-metallic materials, and is widely used in construction, automobiles, electronics, electrical appliances and daily household goods

6. Urea-formaldehyde resin, phenolic aldehyde, melamine-formaldehyde adhesive

Mainly used in the wood processing industry, the amount of formaldehyde released after use is higher than the international standard. Adhesives for wood processing: Used for MDF, plasterboard, plywood and particleboard

7, synthetic adhesive

Mainly used in wood processing, construction, decoration, automobile, shoemaking, packaging, textile, electronics, printing and binding and other fields. At present, China imports nearly 200,000 tons of synthetic adhesives every year, including hot melt adhesives, silicone sealing adhesives, polyacrylic adhesives, polyurethane adhesives, automotive PVC plastic adhesives and so on. At the same time, about 20,000 tons of synthetic adhesives are exported every year, mainly polyvinyl acetate, polyvinyl formaldehyde and pressure sensitive adhesives. ‍

02 Classification by use

1, sealing adhesive

It is mainly used for the connection of doors, Windows and prefabricated houses. The high-grade sealing adhesives are silicone and polyurethane adhesives, and the intermediate ones are neoprene rubber adhesives and polyacrylic acids. In China, the construction adhesive market, silicone adhesives, polyurethane sealing adhesives should be the direction of future development, the current account for about 30% of the sales of building sealing adhesives.

2. Adhesive for building structure

It is mainly used for joining between structural units. For example, the external repair of reinforced concrete structures, metal reinforcement fixing and construction site construction, epoxy resin series adhesives are generally considered.

3, automotive adhesive

It is divided into 4 kinds, namely, adhesive for car body, interior decoration, windshield and chassis of car body. At present, the annual consumption of automotive adhesives in China is about 40,000 tons, of which the largest use is PVC plastic adhesives, neoprene rubber adhesives and asphalt series adhesives.

4. Adhesive for packaging

It is mainly used to make pressure sensitive tape and pressure sensitive label, and glue the surface of paper, plastic, metal and other packaging materials. The adhesive used for the packaging material of paper is polyvinyl acetate emulsion. Adhesives for plastic and metal packaging materials are polyacrylic acid emulsions, VAE emulsions, polyurethane adhesives and cyanoacrylate adhesives.

5, electronic adhesive

Less consumption, currently less than 10,000 tons per year, most of them are used for integrated circuits and electronic products, and are mainly used epoxy resins, unsaturated polyester resins, silicone adhesives. We can supply the sealing adhesives for 5 micron thick electronic components by ourselves, but the adhesives for 3 micron thick electronic components need to be imported from abroad.

6. Adhesive for shoe making

The annual consumption is about 125,000 tons, of which 110,000 tons are needed for neoprene adhesives and about 15,000 tons for polyurethane adhesives. Because neoprene rubber adhesives need to use benzene as a solvent, and benzene is harmful to the human body, the development should be limited, in order to meet the development needs of the footwear industry, the use of polyurethane series adhesives will be the direction.

03 Classified by physical form

1. Paste sealant

This kind of sealant is basically used in static joints, and the use period is generally 2 years or more. Three main materials are usually used: oil and resin, polybutylene, asphalt.

2. Liquid elastomer sealant

Such sealants include liquid polymers that are vulcanized to form a truly elastic state and have the ability to withstand repeated joint deformation. Polymer elastomers used in elastomer sealants include liquid polysulfide rubber, thioterminal polypropylene ether, liquid polyurethane, room temperature vulcanized silicone rubber and low molecular weight butyl rubber. This type of sealant is usually combined into two components, and the two components are mixed when used.

3. Hot melt sealant

Hot melt sealant is also called hot construction sealant. It refers to a sealant based on elastomer and thermoplastic resin admixture. This type of sealant is usually extruded directly into the joint by a certain mouth model under heating (150 ~ 200 ° C). Thermal construction can improve the wetting ability of the sealant to the bonded base material, so it has good adhesion to most of the bonded base material. Once placed in the appropriate position, it is cooled to form or film, becoming a strong elastic body with little shrinkage. The main materials of hot construction sealant are isobutylene polymer, EPDM rubber and thermoplastic styrene Block copolymer. They are usually blended with thermoplastic resins such as EVA, EEA, polyethylene, polyamide, polyester, etc.

4. Liquid sealant

This kind of sealant is mainly used for sealing the mechanical joint, to replace the solid sealing material, namely the solid washer, to prevent the leakage of the internal fluid of the machinery from the joint. This kind of sealant is usually made of polymer materials such as rubber, resin and so on as the main material, and then with fillers and other components. Liquid sealant is usually divided into four categories: non-dry adhesive type, semi-dry viscoelastic type, dry adhesion type and dry stripping type. Select according to the specific parts and requirements.