Adhesive FAQ & Glossary

The state in which two surfaces are held together by interfacial forces which may consist of valence forces or interlocking action, or both.

Fine threads of adhesive stretched between the applicator and substrate during high-speed hot-melt application. Often linked to rheology, temperature, and open-time settings on packaging lines.

A coating applied to a substrate to provide resistance against liquids, oils, grease, oxygen, or moisture vapor. In paper packaging, often used to replace PE liners while supporting repulpable structures.

Unwanted sticking of coated or adhesive-coated surfaces before use, especially in wound master rolls of heat-seal paper. Controlled through coating level, COF, and storage conditions.

A standardized measure of water absorption into paper or board (often reported in g/m²). Used to evaluate how much moisture a substrate or barrier layer allows under test conditions.

The state in which the particles of a single substance are held together by primary or secondary valence forces.

A measure of how easily one surface slides against another. In flexible packaging, low COF on forming films and coated paper helps VFFS and pouch lines run without jamming or misfeeds.

A surface treatment that increases substrate surface energy (dyne level) to improve wet-out and bond strength for adhesives and coatings on films, plastics, and some coated papers.

The process by which an adhesive changes from a liquid to a solid state, often involving a chemical reaction or physical change.

A supplier document stating that a specific adhesive or coating grade meets defined regulatory requirements (e.g., FDA food-contact rules, REACH) for an intended application. Often issued per batch for audits.

A bond designed to fail by tearing the substrate (fiber tear) or delaminating the structure when tampered with. Common in security bags, envelopes, and tamper-evident packaging.

A measure of surface energy. Higher dyne levels generally indicate better wettability and adhesion potential for water-based adhesives.

A widely used hot-melt polymer family for packaging and converting. Often chosen for cost efficiency; thermal stability and char behavior vary by grade and operating window.

A mixture of two or more liquids that are normally immiscible. In adhesives, typically polymer particles dispersed in water.

A U.S. FDA regulation covering adhesives used as components of articles for packaging, transporting, or holding food, typically where the adhesive does not directly contact food (indirect contact).

A U.S. FDA regulation for components of paper and paperboard intended for direct contact with aqueous and fatty foods. Relevant to straws, cups, bowls, and similar fiber articles.

Evidence that bond failure occurs within the paper fiber structure rather than at the adhesive interface. Often used as a quality indicator for paper bag handles, cartons, and security seals.

The initial strength of an adhesive bond immediately after assembly, before full curing has occurred.

A coating applied to a substrate that forms a seal when heat and pressure are applied. Used in blister packs, pouches, lidding films, and paper-based seal structures.

A hot-melt adhesive route engineered for pressure-sensitive performance (tack, peel, and coat weight control) on tapes, labels, and specialty PSA constructions.

A thermoplastic adhesive that is solid at room temperature and becomes liquid when heated for application.

The minimum temperature at which a heat-seal coating begins to form an effective seal under defined pressure and dwell time. Critical for matching sealing bars, line speed, and substrate pairs.

A class of polyolefin hot-melt chemistry often selected for cleaner machining, lower char, and more consistent performance on high-speed lines compared with conventional EVA grades.

The transfer of chemical substances from packaging materials into food. Regulatory limits depend on region (FDA, EU Framework Regulation 1935/2004) and the specific article structure.

The time interval between applying the adhesive and assembling the parts, during which the adhesive remains effective.

A heat-seal bond engineered to open with controlled peel force (e.g., tray lidding, easy-open pouches) without destroying the entire package structure.

Per- and polyfluoroalkyl substances used historically for water and grease resistance. Increasingly restricted; buyers often require third-party PFAS screening beyond supplier self-declarations.

A substance that has a molecular structure consisting chiefly or entirely of a large number of similar units bonded together.

An adhesive that forms a bond when pressure is applied to marry the adhesive with the adherend.

EU Regulation (EC) No 1907/2006 on Registration, Evaluation, Authorisation and Restriction of Chemicals. Governs chemical safety for substances used in adhesive formulations sold into Europe.

Paper products or coated structures that can be recycled through standard paper pulping processes without unacceptable contamination or fiber loss.

The study of the flow of matter, primarily in a liquid state.

The time required for an adhesive to achieve enough strength to hold the substrates together without assistance.

The ability of an adhesive to resist forces that attempt to slide the bonded surfaces past each other.

The percentage of non-volatile material in an adhesive formulation.

The material to which an adhesive or coating is applied.

Directive (EU) 2019/904 addressing single-use plastics and certain packaging structures. Relevant when assessing whether barrier layers function as structural plastic components.

Substances of Very High Concern under REACH. Formulations for EU markets are typically screened so SVHCs remain below reporting thresholds (commonly 0.1% w/w).

The property of an adhesive that enables it to form a bond of measurable strength immediately after contact under low pressure.

A supplier document listing key performance and application data (viscosity, solids, application temperature, bond targets) for a specific product grade.

A common water-based adhesive polymer family for paper converting. Often chosen for flexibility, fiber penetration, and repulpable paper applications.

Organic chemicals that have a high vapor pressure at ordinary room temperature.

A measure of a fluid's resistance to flow.

A label adhesive designed to detach cleanly during bottle washing or recycling processes, supporting returnable glass and PET recovery streams.

The tack of an adhesive before the solvent or water has evaporated.