Different Types of Adhesive Glue

Glue is a chemical bond that involves two natural forces – cohesion and adhesion. It can be used to bind a variety of materials together.

It is easy to use and has a high tensile strength. It also dries quickly. It is a good choice for quick repair projects. It should not be used in humid weather.

Hot-melt adhesives

Hot-melt adhesives (HMA) are thermoplastic glues that liquefy when heat is applied. They require no water or solvents to set and form bonds adhesive glue in their molten state, which allows for multiple applications before they solidify. They are used to bond a variety of materials, including plastics and metals.

Typical HMA formulations are composed of four ingredients: polymers, tackifiers, plasticizers, and antioxidants. The characteristics of a particular formula can be controlled by selecting different types and quantities of these components. The polymers are responsible for the adhesive’s strength, flexibility, and temperature resistance. The tackifiers determine how quickly the hot melt adheres to substrates and control the duration of its liquid period. The plasticizers add flexibility and improve the durability of the finished adhesive. The antioxidants keep the HMA from spoiling or degrading while in use or storage.

The temperature resistance of a hot-melt adhesive is determined by the type of polymer and its molecular weight. For example, some standard packaging adhesives are made of polyethylene, which is temperature resistant up to 80degC continuously and 95degC for shorter periods. Some advanced formulas, like Henkel’s TECHNOMELT SUPRA line of high-performance HMAs, are produced with metallocene catalyzed polyolefins that deliver more stability, longer pot life, and reduced downtime due to nozzle blockage and charring.

As the need for fast and dependable assembly continues to grow, Henkel’s pressure-sensitive adhesives are used in a variety of industries and applications. For instance, automotive industry manufacturers rely on Henkel’s advanced adhesives to facilitate electrical interconnectivity and deliver critical protection for reliable performance.

Cold-melt adhesives

Using the same base polymers as traditional hot melts, cool-melt adhesives can be applied at lower temperatures. They can be shaped by dipping or spraying, and they are especially popular with hobbyists and crafters for affixing items. Unlike traditional hot-melt glues, which are typically applied at 350deg F (177deg C), cool-melt glues can be applied at 200deg F (93deg C) and still have good bond strength values.

Hot-melt adhesives are used throughout industrial production for a wide variety of applications. Whether it is for food packaging, woodworking, product assembly or labelling, these adhesives are versatile, quick to set and have minimal shrinkage. They are also environmentally friendly, odorless and easy to use.

Typical hot-melt formulas are composed of an adhesive polymer and a tackifying resin that are mixed with additives to provide specific bonding characteristics. Additive formulations can include plasticizers that reduce melt viscosity and improve wetting to substrates.

Whether used in a bead or line application, or in spraying, an advanced hot melt dispensing system can dramatically reduce downtime, improve workplace safety and increase operational efficiency. These systems offer a variety of other benefits, including intelligent monitoring capabilities that track adhesive usage for long-term recordkeeping and expense management purposes. Moreover, hot-melt adhesives are often composed of renewable materials and are compatible with a wide variety of recycled or compostable substrates.

Natural adhesives

Glues have many uses in nature, including attaching objects to surfaces, sealing and waterproofing, and for defence. Many creatures use adhesive secretions to move around, such as climbing plants and barnacles. Other creatures use glue as a means of communication and attachment, such as geckos and sea cucumbers. In some cases, these adhesive secretions help them get away from predators or prey.

Natural adhesives are derived from plant materials adhesive glue and resins, vegetable starch, natural rubber, animal products, such as milk proteins casein and hide-based animal glues, and mineral substances, such as pozzolana and bitumen pitch. They can be classified as either heat curing or moisture curing. Heat-curing adhesives consist of a pre-made mixture of two or more components that react when heat is applied. They also cross-link, creating polymers like epoxies and urethanes.

Pine pitch glue is a common natural adhesive that has been used from antiquity for a wide variety of traditional crafts and other purposes. It is made from rendered pine sap, ground plant fibers, and powdered charcoal in specific proportions and is sold by the ounce on a stick for ease of application.

Currently, most adhesives on the market are based on elastomers and thermosets that are derived from petroleum. These chemicals are harmful to human health and the environment. Developing new adhesives that are both non-petroleum based and less toxic is an important goal for a sustainable society.

Synthetic adhesives

Unlike natural adhesives, synthetic glues are produced in a factory. They have a higher level of performance and consistency and can be used in a variety of conditions and applications. They can also be modified in many ways to achieve the desired result. They are used in many industries and are a key component of the automotive industry, for example, to bond plastic parts. They are also used in manufacturing and construction.

Synthetic adhesives are made from polymers that form long chains and can bind materials together. They can be classified as either thermoplastic or thermoset. Thermoplastics provide good strength at normal temperatures and can be softened for application without degradation. These include nitrocellulose, vinyl acetate-ethylene copolymers, polyvinyl acetate, and polyethylene. Thermosets cure by chemical reaction and are hard when dry. They include phenolics, urethanes, and acrylates.

The use of adhesives for gluing wood is important to the timber construction industry. They can be cured at lower temperatures than other binding techniques and have many advantages, including a more efficient distribution of stress across the joint, a lower cost, and a wider range of application. They can also be formulated to meet specific requirements, such as heat resistance. However, the quality of wood-adhesive bonds is dependent on the selection and design of glued products. This is a critical issue for the timber construction sector, as a weak bond can fail due to moisture or temperature extremes.