Classification of adhesives and their uses

Glue is an intermediate connecting two materials. It mostly appears as water agent. It belongs to the category of fine chemicals. Common ones are instant glue, epoxy resin bonding, anaerobic glue, UV glue, hot melt adhesive, pressure sensitive adhesive, latex and so on. The following Qingdao Sino polyethylene wax editor will analyze the most detailed classification and use of adhesives for you.

Viscosity of glue:

The viscosity of the glue is measured with a Brookfield viscometer in “cps centipoise”. The viscosity reading of glue is generally between 300 and 30000cps. In water-soluble adhesives, the solid content does not determine the viscosity of the glue, but the plasticizers, tackifiers, etc. in the formula of the glue, which affect the viscosity of the glue. In general, the higher the ambient temperature is, “viscosity↓”, “temperature↓viscosity↑”. The viscosity of water at 27°C is “1”.

Classification by ingredients:

There are many types of adhesives, the more common ones are: urea-formaldehyde resin adhesives, polyvinyl acetate adhesives, polyacrylic resin adhesives, polyacrylic resins, polyurethane adhesives, hot melt adhesives, epoxy resin adhesives, synthetic adhesives and so on.

1. Urea-formaldehyde resin, phenolic, melamine-formaldehyde adhesive: mainly used in the wood processing industry, the formaldehyde emission after use is higher than the international standard.

Adhesives for wood processing: for medium density fiberboard, gypsum board, plywood and particleboard, etc.

2. Polyacrylic resin: mainly used in the production of pressure-sensitive adhesives, but also in the textile and construction fields.

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

3. Polyurethane adhesive: It can bond a variety of materials. After bonding, it can still maintain the physical and chemical properties of the material at low or ultra-low temperature. It is mainly used in shoemaking, packaging, automobiles, magnetic recording materials and other fields.

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, etc. At present, the main domestic production and use is EVA hot melt adhesive. The main raw materials of polyolefin series adhesives are ethylene series, SBS, SIS copolymer.

5. Epoxy resin adhesive: It can bond between metals and most non-metallic materials, and is widely used in construction, automobiles, electronics, electrical appliances and daily household items.

6. Silicone adhesive: It is a kind of sealing adhesive, which has the characteristics of cold resistance, heat resistance, aging resistance, water resistance, moisture resistance, high tensile fatigue strength, small permanent deformation and non-toxicity. In recent years, such adhesives have developed rapidly in China, but at present, the raw materials of organic silicone adhesives in my country are partly imported.

7. Synthetic adhesive: mainly used in wood processing, construction, decoration, automobile, shoemaking, packaging, textile, electronics, printing and binding and other fields. At present, my country imports nearly 200,000 tons of synthetic adhesives every year, including hot melt adhesives, silicone sealant adhesives, polyacrylic acid adhesives, polyurethane adhesives, and PVC plastic adhesives for automobiles. At the same time, about 20,000 tons of synthetic adhesives are exported every year, mainly polyvinyl acetate, polyvinyl acid formal and pressure-sensitive adhesives. ‍

According to the use is divided into:

1. Sealing adhesive: mainly used for the connection of doors, windows and prefabricated houses. The high-end sealing adhesives are silicone and polyurethane adhesives, and the mid-range ones are neoprene adhesives, polyacrylic acid, etc. In my country, in the construction adhesive market, silicone adhesives and polyurethane sealing adhesives should be the direction of future development. At present, they account for about 30% of the sales volume of construction sealing adhesives.

2. Adhesive for building structure: mainly used for the connection between structural units. Such as external repair of reinforced concrete structures, metal reinforcement and fixation, and construction on site, epoxy resin series adhesives are generally considered.

3. Adhesives for automobiles: divided into 4 types, namely, adhesives for car body, interior decoration, windshield and chassis.

At present, the annual consumption of automotive adhesives in my country is about 40,000 tons, of which the most used are PVC plastic adhesives, neoprene adhesives and asphalt series adhesives.

4. Adhesives for shoemaking: 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. Since neoprene adhesives require benzene as a solvent, and benzene is harmful to the human body, the development should be restricted. In order to meet the development needs of the footwear industry, the use of polyurethane series adhesives will be the direction.

5. Adhesive for packaging: It is mainly used to make pressure-sensitive tapes and pressure-sensitive labels, and to bond the surface of packaging materials such as paper, plastic, and metal. The adhesive for paper packaging materials is polyvinyl acetate emulsion. Adhesives for plastic and metal packaging materials are polyacrylic emulsions, VAE emulsions, polyurethane adhesives and cyanoacrylate adhesives.

6. Electronic adhesives: The consumption is relatively small, currently less than 10,000 tons per year, and most of them are used in integrated circuits and electronic products. Now epoxy resin, unsaturated polyester resin, and silicone adhesive are mainly used. We can supply end-capping adhesives for electronic components with a thickness of 5 microns, but the adhesives for electronic components with a thickness of 3 microns need to be imported from abroad.

Classification by physical form:

1. Classification by adhesive hardening method

Low temperature hardening code is a; normal temperature hardening code is b; heating hardening code is c; suitable for various temperature areas hardening code is d; , radiation) curing code is g; hot melt cold hardening code is h; pressure-sensitive adhesive code is i; coagulation or condensation code is j, other codes are k.

2. Classification according to adhesive adherends

The code for many types of materials is A; the code for wood is B; the code for paper is C; the code for natural fibers is D; the code for synthetic fibers is E; the code for polyolefin fibers (excluding E) is F; the code for metals and alloys is G; The code for sticky metals (gold, silver, copper, etc.) is H; the code for metal fibers is I, and the code for inorganic fibers is J; the code for transparent inorganic materials (glass, gemstones, etc.) is K; the code for opaque inorganic materials is L; the code for natural rubber is M; synthetic rubber code is N; difficult-to-stick rubber (silicone rubber, fluorine rubber, butyl rubber) code is O, hard plastic code is P, plastic film code is Q; leather, synthetic leather code is R, foam plastic code It is S; hard-to-stick plastics and films (fluoroplastics, polyethylene, polypropylene, etc.) are code-named T; living tissue bones and dentine materials are code-named U; others are code-named V.

3. Glue status:

Solvent-free liquid code is 1; 2 organic solvent liquid code is 2; 3 water-based liquid code is 3, 4 paste, paste code is 4, 5 powder, granule, block code is 5; 6 sheet, film Shape, mesh, ribbon code is 6; 7 filament, strip, rod code is 7.

4. Sealant

4.1 Classification by sealant vulcanization method

(1) Moist air vulcanized sealant

This family of sealants is vulcanized with moisture in the air. It mainly includes one-component polyurethane, silicone rubber and polysulfide rubber. The polymer base material contains active groups, which can react with water in the air to form cross-linking bonds, so that the sealant is vulcanized into a network structure.

(2) Chemical vulcanization sealant

Two-component polyurethane, silicone, polysulfide, neoprene, and epoxy sealants fall into this category and are generally cured at room temperature. Certain one-component chlorosulfonated polyethylene and neoprene sealants and polyvinyl chloride sol paste sealants must be cured by chemical reaction under heating conditions.

(3) Thermal transformation type sealant

The combination of plasticizer-dispersed polyvinyl chloride resin and bituminous rubber is two different types of thermal transition systems. Vinyl plasticizers are liquid suspensions at room temperature and harden by heating to solidify; rubber-asphalt sealants are hot-melt. polyethylene wax, polyethylene wax manufacturer, oxidized polyethylene wax

(4) Oxidation hardening sealant

Surface-drying sealants for inlay or installation glass are mainly based on dry or semi-dry vegetable or animal oils, which can be refined polymerized, blown or chemically modified.

(5) Solvent volatilization solidifying sealant

This is a sealant based on non-viscous polymer after solvent evaporation. This type of sealant mainly includes butyl rubber, high molecular weight polyisobutylene, acrylate with a certain degree of polymerization, chlorosulfonated polyethylene and neoprene rubber sealants.

4.2 Classification by sealant form

(1) Paste sealant

This type of sealant is basically used in static joints, and the service life is generally 2 years or more. Usually 3 main materials are used: oil and resin, polybutene, bitumen.

(2) Liquid elastomer sealant

These sealants include liquid polymers that vulcanize to a true elastic state and have the ability to withstand repeated seam deformation. The polymer elastomers used in elastomer sealants include liquid polysulfide rubber, mercapto-terminated polypropylene ether, liquid polyurethane, room temperature vulcanized silicone rubber, and low molecular weight butyl rubber. This type of sealant is usually formulated into two components, and the two components are mixed when used.

(3) Hot melt sealant

Hot melt sealant is also called thermal construction sealant. Refers to a sealant based on a blend of elastomer and thermoplastic resin. This type of sealant is usually extruded directly into the seam through a certain mouth mold under the condition of heating (150 ~ 200 ℃). Hot application can improve the wetting ability of the sealant to the bonded substrate, so it has good adhesion to most bonded substrates. Once in place, it cools and forms or forms a film into a strong elastomer with little shrinkage. The main materials of thermal construction sealants are mainly isobutylene polymers, EPDM rubber and thermoplastic styrene block copolymers. They are usually blended with thermoplastic resins such as EVA, EEA, polyethylene, polyamide, polyester and the like.

(4) Liquid sealant

This type of sealant is mainly used for the sealing of mechanical joint surfaces to replace solid sealing materials, namely solid gaskets, to prevent mechanical internal fluid from leaking from joint surfaces. This type of sealant is usually made of polymer materials such as rubber, resin, etc. as the main material, together with fillers and other components. Liquid sealants are usually divided into four categories: non-drying adhesive type, semi-drying viscoelasticity, dry adhesion type and dry peelable type. Choose according to the specific use parts and requirements. polyethylene wax, oxidized polyethylene wax, polyethylene wax manufacturers

4.3 Classification by performance of sealant after construction

(1) Curing sealant

Curing sealants can be divided into two types: rigid sealants and flexible sealants: a) Rigid sealants form hard solids after vulcanization or solidification, and rarely have elasticity; some varieties of such sealants play both sealing and glueing functions The representative sealant is a sealant based on resins such as epoxy resin, polyester resin, polyacrylate, polyamide and polyvinyl acetate. b) Flexible sealants remain soft after vulcanization. They are generally based on rubber elastomers. The flexibility varies greatly, and the hardness (Shore A) is in the range of 10 to 80. Some varieties of this type of sealant are pure rubber, and most of them have the properties of good adhesives.

(2) Non-curing sealant

This type of sealant is a soft solidifying sealant that remains non-drying after construction. Usually a paste, it can be applied to the joints with a spatula or brush, and many sealants of different viscosities and properties can be formulated.

5. Other adhesives:

Metal Structural Adhesive, Polymer Structural Adhesive, Photosensitive Sealing Structural Adhesive, Other Composite Structural Adhesive

Thermosetting polymer adhesives: epoxy resin adhesive, polyurethane (PU) adhesive, amino resin adhesive, phenolic resin adhesive, acrylic resin adhesive, furan resin adhesive, meta-benzenediphenol-formaldehyde resin adhesive, xylene-formaldehyde resin adhesive, no Saturated polyester glue, composite resin glue, polyimide glue, urea-formaldehyde resin glue, other polymer glue

Sealant: RTV silicone rubber, epoxy resin sealant, polyurethane sealant, unsaturated polyester, acrylic, sealing putty, neoprene sealant, elastomer sealant, liquid gasket, polysulfide Rubber sealant, other sealants

Hot-melt adhesive: hot-melt adhesive strip, rubber pellet, rubber powder, EVA hot-melt adhesive, rubber hot-melt adhesive, polypropylene, polyester, polyamide, polyurethane hot-melt adhesive, styrene hot-melt adhesive, new hot-melt adhesive , polyethylene and ethylene copolymer hot melt adhesives, other hot melt adhesives

Water-based adhesives: acrylic emulsion, vinyl acetate emulsion, polyvinyl acetal glue, emulsion glue, other water-based glue

Pressure-sensitive adhesive (self-adhesive): glue, waxes for hotmelt adhesive,  adhesive tape, solvent-free pressure-sensitive adhesive, solvent-based pressure-sensitive adhesive, cured pressure-sensitive adhesive, rubber pressure-sensitive adhesive, acrylate pressure-sensitive adhesive, other pressure-sensitive adhesives

Solvent-based glue: resin solution glue, rubber solution glue, other solvent glue

Inorganic adhesives: hot melt inorganic adhesives, natural dry inorganic adhesives, chemical reaction inorganic adhesives, hydraulic inorganic adhesives, other inorganic adhesives

Thermoplastic polymer adhesive: solid polymer glue, solution polymer glue, emulsion polymer glue, monomer polymer glue, other thermoplastic polymer glue

Natural Adhesives: Protein Adhesives, Carbohydrate Adhesives, Other Natural Adhesives

Rubber adhesives: silicone rubber adhesives, neoprene adhesives, nitrile rubber adhesives, modified natural rubber adhesives, chlorosulfonated polyethylene adhesives, polysulfide rubber adhesives, carboxyl rubber Adhesives, Polyisobutylene, Butyl Rubber Adhesives, Other Rubber Adhesives

High temperature resistant adhesive: organic silica gel, inorganic adhesive, high temperature mold resin adhesive, metal high temperature adhesive, other high temperature resistant adhesive

Polymer adhesives: nitrile polymer adhesives, polysulfide rubber adhesives, polyvinyl chloride adhesives, polybutadiene adhesives, perchloroethylene adhesives, other polymer adhesives

Repairing agent: metal repairing agent, high temperature repairing agent, emergency repairing agent, wear-resistant repairing agent, corrosion-resistant repairing agent, plastic repairing agent, other repairing agent

Medical glue, glue for paper products, magnetic conductive glue, anti-magnetic glue, fireproof glue, anti-quenching glue, anti-quenching glue, animal glue, vegetable glue, mineral glue, food-grade adhesive, other glues