Adhesives in the footwear industry

Abstract

Footwear manufacturing is basically a process of transformation and assembly of various components made up of several materials where different adhesives play a key role, because without them, the shoe would lack shape and structure. This paper aims to understand the importance of adhesives in the footwear industry. It is necessary to identify the different processes in a shoemaking where adhesives are involved and the different adhesive joints produced, as well as their technical requirements. The adhesive joint performance will depend on the different adherends' nature used as footwear materials, the joint design, the surface treatments, the adhesive properties which depend on their formulation, and so on. Adhesive joints in a shoe act under different stress types (peel, shear, tensile, etc.). The most disfavourable are the peel stress. For that reason, the peel strength test is one of the most common to evaluate adhesive joints' performance. When heat resistance is an important adhesive requirements, a creep test is carried out. Furthermore, aging tests are undertaken in order to evaluate durability. This methodology is described in this paper. In the literature, one can find several papers on adhesives, specifically on their mechanical properties. However, there is little research related to footwear applications, including not only the mechanical properties that this industry demands, but also the composition of the adhesives. Therefore, this paper aims to connect the important mechanical properties for the footwear industry with the constituents of the adhesives. However, other properties are also important, such as viscosity, wettability, compatibility, etc., depending on the materials and the adhesive joint type.

Development and Aging Behaviour of Solvent-Based Polychloroprene Rubber Nano-Adhesive Using Multiwall Carbon Nanotubes

“…In solvent-based technology, the solvent evaporates very quickly from the surface, and very high bond strength is observed, which increases with time [5]. Some of the properties which affect the strength and its performance are viscosity [6], storage life [7] [8], working life, tack time [9] [10], acid acceptance [11], surface free energy and wettability [12] Phenolic resins are widely used in adhesive formulation; however, many alternatives are now being developed. Modified resins are also used in the adhesive formulation.…”

Sustainable adhesives and adhesion processes for the footwear industry

“…In this sense, a shoe is made up of several components from different materials where adhesive joints are mainly responsible of their shape and structure. 1,7 More precisely, the upper-to-sole joint is the most demanding process in footwear manufacturing in terms of bond strength. The proper choice of adhesive, as well as the right material surface treatment prior to bonding, are fundamental to fulfil footwear requirements according to quality standards.…”

Comparative Life Cycle Assessment among Three Polyurethane Adhesive Technologies for the Footwear Industry

“…Therefore, it is very important to find alternatives to minimize environmental impacts on sustainability in the Brazilian shoe industry. − Moreover, according to Milà et al the manufacturing stage showed the main impacts that contribute to the environmental profile for the footwear product system life cycle. This occurs mainly due to energy requirements in many shoe manufacturing steps, including drying both adhesives and primers, which leads to another environmental burden: organic emissions. , According to Paiva et al . the footwear industry has a close association with the adhesives industry, using bonding techniques to join the variety of materials employed in assembling shoes.…”

“…Water-based adhesive (WBA) is a chemical material with good performance in shoe bonding that is easy and fast to apply. The WBA can be manually applied to the joining surfaces, but heating equipment is required during bonding processes in order to evaporate water, similar to solvent-based adhesive. , …”

“…However, they might cause less environmental impact, because they reduce volatile organic emissions (VOCs), for example, reducing risks to workers’ health and even flammability. , Summarizing, besides differences in manufacturing, water- and solvent-based adhesives differ from the powder-based adhesive (PBA) mainly in relation to application steps. First of all, water and solvent based adhesive do not require the use of energy, because they are usually a manual application, whereas PBA demands electric energy to be used, because it is carried out by machine, and it is a standard industrial process…”