Classification of Adhesives: An Overview of Types and Applications. Adhesives find extensive application across diverse fields, including construction, packaging, aerospace, aviation, electronics, automotive, and mechanical engineering. There are numerous types of adhesives, which can be categorized based on composition, intended use, and physical form. This guide summarizes the classification and applications of adhesives from these three perspectives, aiming to provide valuable insights for readers. I. Classification by Composition: There are many types of adhesives, among which the most common include urea-formaldehyde resin adhesives, polyvinyl acetate adhesives, polyacrylic resin adhesives, polyurethane adhesives, hot-melt adhesives, epoxy resin adhesives, and synthetic adhesives, among others. 1. Silicone adhesives are a type of sealing adhesive characterized by their resistance to cold, heat, and aging; they are also waterproof, moisture-resistant, exhibit high tensile strength under thermal expansion and contraction, exhibit minimal permanent deformation, and are non-toxic. In recent years, the development of such adhesives has progressed rapidly within China; however, the raw materials for silicone adhesives in China still rely partially on imports. 2. Polyurethane adhesives can bond a wide variety of materials and retain the physicochemical properties of the bonded materials even at low or ultra-low temperatures. They are primarily applied in footwear manufacturing, packaging, automotive industries, and magnetic recording materials. 3. Polyacrylic resins are mainly used in the production of pressure-sensitive adhesives, as well as in the textile and construction sectors. Construction adhesives are primarily used for architectural decoration, sealing, or bonding between structural components. 4. Hot-melt adhesives can be classified according to their raw materials into EVA hot-melt adhesives, polyamide hot-melt adhesives, polyester hot-melt adhesives, polyolefin hot-melt adhesives, etc. Currently, EVA hot-melt adhesives are the predominant type produced and utilized in China. The primary raw materials for polyolefin-based adhesives are ethylene-based compounds, SBS, and SIS copolymers. 5. Epoxy resin adhesives can bond metals to most non-metallic materials and are widely used in construction, automotive, electronic, electrical appliance, and household product applications. 6. Urea-formaldehyde, phenolic, and melamine-formaldehyde adhesives are primarily employed in the wood processing industry; however, their post-application formaldehyde emission levels exceed international standards. Adhesives for wood processing are used in medium-density fiberboard, gypsum board, plywood, and particle board. 7. Synthetic adhesives are primarily utilized in wood processing, construction, decoration, automotive, footwear, packaging, textile, electronics, and printing and binding industries. Currently, China imports approximately 200,000 tons of synthetic adhesives annually, including hot-melt adhesives, silicone sealing adhesives, polyacrylic adhesives, polyurethane adhesives, and PVC plastic adhesives for automotive applications. Simultaneously, China exports approximately 20,000 tons of synthetic adhesives each year, mainly consisting of polyvinyl acetate, polyvinyl alcohol-formaldehyde condensates, and pressure-sensitive adhesives.
II. Classification by Use
1. Sealing adhesive
These adhesives are primarily used at the joints of doors, windows, and prefabricated building components. High-end sealing adhesives consist of silicone and polyurethane adhesives, while mid-range options include neoprene rubber-based adhesives and polyacrylic acids. In China’s construction adhesive market, silicone and polyurethane sealing adhesives are poised to become the primary growth directions, currently accounting for approximately 30% of total sales of construction sealing adhesives.
2. Adhesives for building structures
Primarily used for bonding structural units—such as external repair of reinforced concrete structures, metal reinforcement and fixation, and on-site construction of buildings—epoxy resin-based adhesives are generally employed.
3. Automotive adhesives
There are four types: adhesives for the vehicle body, for interior trim, for the windshield, and for the vehicle chassis.
Currently, the annual consumption of automotive adhesives in China is approximately 40,000 tons, with the largest shares coming from polyvinyl chloride plastic adhesives, neoprene rubber adhesives, and bitumen-based adhesives.
4. Packaging adhesives
This product is primarily used to manufacture pressure-sensitive tapes and pressure-sensitive labels, and to bond packaging materials—including paper, plastics, and metals—to their surfaces. For paper packaging materials, the adhesive used is polyvinyl acetate emulsion. For plastic and metal packaging materials, the adhesives used are polyacrylic acid emulsion, VAE emulsion, polyurethane adhesive, and cyanoacrylate adhesive.
5. Adhesives for electronic applications
The annual consumption remains relatively low, currently below 10,000 tons, with the majority of the material being used in integrated circuits and electronic products. The primary adhesives currently employed include epoxy resin, unsaturated polyester resin, and silicone adhesive. We are capable of supplying our own sealing adhesives for electronic components with a thickness of 5 μm; however, adhesives for electronic components with a thickness of 3 μm must be imported from abroad.
6. Adhesives for footwear manufacturing
Annual consumption is approximately 125,000 tons, of which 110,000 tons are for chloroprene rubber-based adhesives and approximately 15,000 tons are for polyurethane adhesives. Since chloroprene rubber-based adhesives require benzene-based solvents—which are harmful to human health—their development should be restricted. To meet the growing demands of the footwear industry, the adoption of polyurethane-based adhesives represents the strategic direction.
III. Classification by Physical Form
1. Sealant
1.1 Classification by curing method of sealants
(1) Moist-air vulcanizing sealant
This class of sealants cures using moisture from the air. It primarily includes single-component polyurethanes, silicone rubbers, and polysulfide rubbers. The polymer matrix contains reactive groups that react with moisture in the air to form crosslinking bonds, thereby curing the sealant into a network structure.
(2) Chemically vulcanized sealant
Bicomponent polyurethane, silicone rubber, polysulfide rubber, neoprene rubber, and epoxy resin sealants all belong to this category, and they are typically cured at room temperature. In contrast, certain monocomponent chlorosulfonated polyethylene and neoprene rubber sealants, as well as polyvinyl chloride colloidal paste sealants, require chemical curing under heated conditions.
(3) Thermoreversible sealant
The sealant composed of plasticizer-dispersed polyvinyl chloride resin and an asphalt-containing rubber constitutes two distinct thermoreversible systems. The vinyl resin plasticized blend exists as a liquid suspension at room temperature and solidifies upon heating; in contrast, the rubber-asphalt blended sealant is thermoplastic.
(4) Oxidation-hardening sealant
Sealants for joint filling or glass installation on dry surfaces primarily utilize dry or semi-dry vegetable or animal oils as their base materials; such oils may be refined, polymerized, blown, or chemically modified.
(5) Solvent-curing sealant
This is a sealant based on non-adhesive polymers after solvent evaporation. Common sealants of this type include butyl rubber, high-molecular-weight polyisobutylene, acrylates of specific degree of polymerization, chlorosulfonated polyethylene, and chloroprene rubber, among others.
1.2 Classification by Sealant Form
(1) Paste-type sealant
This type of sealant is primarily used in static joints, with a service life typically ranging from 2 years to over 2 years. Three primary materials are commonly employed: oil-based and resin-based compounds, polybutene, and bitumen.
(2) Liquid elastomeric sealant
This type of sealant comprises liquid polymers that, upon vulcanization, can attain a truly elastic state, enabling them to withstand repeated joint deformations. The polymer elastomers used in elastomeric sealants include liquid polysulfide rubber, thiol-terminated polyether, liquid polyurethane, room-temperature vulcanizing silicone rubber, and low-molecular-weight butyl rubber, among others. Such sealants are typically formulated as two components, which are then mixed prior to application.
(3) Thermal-melt sealant
Thermoplastic sealant, also known as thermally applied sealant, refers to a sealant whose base material consists of an elastomer blended with a thermoplastic resin. Such sealants are typically extruded directly into joints under heating conditions (150–200 °C) through a specific die. This thermoplastic application method enhances the sealant’s wettability toward the bonded substrate, thereby providing excellent adhesion to most bonded substrates. Once placed in the appropriate position, the sealant cools and solidifies or forms a film, resulting in a rigid elastomer with minimal shrinkage. The primary components of thermoplastic sealants include isobutylene-based polymers, EPDM rubber, and thermoplastic styrene block copolymers, which are commonly blended with thermoplastic resins such as EVA, EEA, polyethylene, polyamide, and polyester.
(4) Liquid sealant
This type of sealant is primarily used for sealing mechanical joint surfaces, serving as a substitute for solid sealing materials—such as solid gaskets—to prevent the leakage of internal fluids through these joint surfaces. Such sealants typically consist of polymer materials, including rubber or resins, as their base components, supplemented with fillers and other additives. Liquid sealants are generally classified into four categories: non-drying adhesive type, semi-drying viscoelastic type, drying adhesive type, and drying removable type; the appropriate category should be selected based on the specific application site and performance requirements.
1.3 Classification based on post-application performance of sealants
(1) Rigid sealant
Cured sealants can be classified into two types: rigid sealants and flexible sealants. a) Rigid sealants, after vulcanization or curing, form a hard solid and rarely exhibit elasticity; some varieties of these sealants serve both sealing and adhesive functions, with representative examples including sealants based on resins such as epoxy resin, polyester resin, polyacrylate, polyamide, and polyvinyl acetate. b) Flexible sealants retain their flexibility after vulcanization; they are typically formulated with rubber elastomers as the base material. Their hardness (Shore A) varies widely, ranging from 10 to 80. Some of these sealants consist of pure rubber, while the majority possess excellent adhesive properties.
(2) Non-curing sealant
This type of sealant is a soft-curing sealant that remains in a non-dry state after application. It typically comes in a paste form and can be applied to joints using a spatula or brush; it can be formulated in combination with various other sealants differing in viscosity and performance characteristics.
2. Classification by adhesive curing method
Low-temperature curing is designated as A; room-temperature curing is designated as B; heat-curing is designated as C; multi-temperature zone curing is designated as D; water-reactive curing is designated as E; anaerobic curing is designated as F; radiation (light, electron beam, or ionizing radiation) curing is designated as G; hot-melt cold-curing is designated as H; pressure-sensitive bonding is designated as I; coagulation or coalescence curing is designated as J; and all other types are designated as K.
3. Classification by adherend
The following material categories are designated by the following codes: A for multiple material types; B for wood; C for paper; D for natural fibers; E for synthetic fibers; F for polyolefin fibers (excluding category E); G for metals and alloys; H for difficult-to-adhere metals (e.g., gold, silver, copper); I for metal fibers; J for inorganic fibers; K for transparent inorganic materials (e.g., glass, gemstones); L for opaque inorganic materials; M for natural rubber; N for synthetic rubber; O for difficult-to-adhere rubbers (e.g., silicone rubber, fluorore rubber, butyl rubber); P for rigid plastics; Q for plastic films; R for leather and synthetic leather; S for foam plastics; T for difficult-to-adhere plastics and films (e.g., fluoropolymers, polyethylene, polypropylene); U for biological tissues, bones, and dental materials; V for other materials.
4. Adhesive state
Solvent-free liquids are designated as 1; organic solvent-based liquids are designated as 2; water-based liquids are designated as 3; paste-or paste-like substances are designated as 4; powdery, granular, or block-shaped substances are designated as 5; sheet-, film-, mesh-, or strip-shaped substances are designated as 6; filament-, strip-, or rod-shaped substances are designated as 7.
5. Other adhesives (not commonly used)
Metal structural adhesives, polymer structural adhesives, photosensitive structural adhesives, and other composite structural adhesives
Thermosetting polymer adhesives: epoxy resin adhesive, polyurethane (PU) adhesive, amino resin adhesive, phenolic resin adhesive, acrylic resin adhesive, furan resin adhesive, m-cresol-formaldehyde resin adhesive, dimethylcresol-formaldehyde resin adhesive, unsaturated polyester adhesive, composite resin adhesive, polyimide adhesive, urea-formaldehyde resin adhesive, and other polymer adhesives
Sealants: room-temperature vulcanizing silicone rubber, epoxy resin sealants, polyurethane sealants, unsaturated polyester sealants, acrylate sealants, sealing putty, chloroprene rubber sealants, elastomeric sealants, liquid sealing gaskets, polysulfide rubber sealants, and other sealants
Hot-melt adhesives: hot-melt adhesive strips, adhesive granules, adhesive powders, EVA hot-melt adhesives, rubber-based hot-melt adhesives, polypropylene, polyester, polyamide, polyurethane hot-melt adhesives, styrene-based hot-melt adhesives, novel hot-melt adhesives, polyethylene and ethylene copolymer hot-melt adhesives, and other hot-melt adhesives
Water-borne adhesives: acrylic emulsions, vinyl acetate emulsions, polyvinyl alcohol acetal adhesives, emulsion adhesives, and other water-borne adhesives
Pressure-sensitive adhesives (self-adhesive): adhesives, adhesive tapes, solvent-free pressure-sensitive adhesives, solvent-based pressure-sensitive adhesives, cured pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, acrylate-based pressure-sensitive adhesives, and other pressure-sensitive adhesives
Solvent-based adhesives: resin-based adhesives, rubber-based adhesives, and other solvent-based adhesives
Inorganic adhesives: hot-melt inorganic adhesives, air-drying inorganic adhesives, chemically curing inorganic adhesives, water-curing inorganic adhesives, and other inorganic adhesives
Thermoplastic polymer adhesives: solid polymer adhesives, solution-based polymer adhesives, emulsion-based polymer adhesives, monomer-based polymer adhesives, and other thermoplastic polymer adhesives
Natural adhesives: protein-based adhesives, carbohydrate-based adhesives, and other natural adhesives
Rubber adhesives: silicone rubber adhesives, chloroprene rubber adhesives, nitrile rubber adhesives, modified natural rubber adhesives, chlorosulfonated polyethylene adhesives, polysulfide rubber adhesives, carboxyl rubber adhesives, polyisobutylene, butyl rubber adhesives, and other rubber adhesives
High-temperature resistant adhesives: silicone adhesives, inorganic adhesives, high-temperature mold resins, metal high-temperature adhesives, and other high-temperature resistant adhesives
Polymer adhesives: nitrile polymer adhesives, polysulfide rubber adhesives, polyvinyl chloride adhesives, polybutadiene adhesives, chlorinated polyethylene adhesives, and other polymer adhesives
Repair agents: metal repair agents, high-temperature repair agents, emergency repair agents, wear-resistant repair agents, corrosion-resistant repair agents, plastic repair agents, and other repair agents
Medical adhesives, adhesives for paper products, magnetic-guiding adhesives, anti-magnetic adhesives, fire-resistant adhesives, heat-resistant adhesives, crack-resistant adhesives, animal-derived adhesives, plant-derived adhesives, mineral-based adhesives, food-grade adhesives, and other adhesives.
Selection of the right grade from the full JOME product catalogue usually starts with drawings and service conditions. The companion piece on A Guide to Structural Adhesives sits alongside this guide, the JOME adhesive factory in Shanghai lists every family, and the reach the JOME technical staff handles enquiries.