Sustainable Adhesives

Sustainable Adhesives Growing global populations and rising living standards increase demand for adhesives, while environmental concerns are driving the development of more eco-friendly, sustainable adhesive solutions. As a result, demand for sustainable adhesives has reached unprecedented levels. As a result of research conducted and advancing technology, increasingly innovative and sustainable adhesive solutions are emerging. In line with these developments, many industries are adopting sustainable adhesive products and supporting work in this field. Sustainable adhesives contain very little solvent, and some contain none at all. Solvent-free adhesives have less negative environmental impact. This is because they are lighter in weight, require less material, and have minimal VOC (volatile organic compound) emissions. This means there is much less, and in some cases no, VOC emission during application and curing. Volatile organic compounds are substances with high vapor pressure and low water solubility. Many VOCs are man-made chemicals used and produced in the manufacture of paints, pharmaceuticals and refrigerants. VOCs include industrial solvents such as trichloroethylene, fuel oxygenates such as methyl tert-butyl ether (MTBE), and by-products generated through chlorination in water treatment such as chloroform. VOCs are generally components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning substances. VOCs are also among groundwater contaminants. VOCs are released as gases from certain solids and liquids. VOCs contain various chemicals that can cause health problems in the short and long term. Their concentrations indoors are up to ten times higher than outdoors. VOC emissions are generated by a wide range of products numbering in the thousands. These products include paints and varnishes, paint strippers, cleaning products, pesticides, construction materials, furniture, office equipment such as photocopiers and printers, correction fluids, carbonless copy paper, adhesives, felt-tip markers, and graphic and craft materials including photographic solutions. In the development of new products and systems, regulations and standards for more sustainable products have become a priority. For this reason, many organizations, particularly in developed countries, have established necessary legal regulations by setting rules and standards for products that cause VOC emissions. In this context, VOC emissions from chemical products have been strictly controlled for a long time in the US and EU. Efforts to prevent VOC emissions are gaining increasing importance in other markets such as Asia and South America. Many adhesives contain petroleum-based and environmentally harmful raw materials. However, it is possible to replace these raw materials entirely or partially with materials derived from natural sources. The use of natural raw materials makes adhesives sustainable. Sustainable adhesives have many advantages, but achieving them requires replacing existing products and incorporating new technologies into the production process. Sustainable adhesives are generally divided into three groups: Solvent-free adhesives: Today, many adhesives are made with less solvent by increasing the solids content in their composition. However, 100% solids adhesives such as hot melt contain no solvent at all. Solvent-free adhesives are widely used in solvent-free composite processes, which are of great importance for promoting and adopting solvent-free composite technology. These types of adhesives can solve problems arising from different composite structural materials in the flexible packaging industry. Cleaning mixers and solvent-free machines can save time, increase production efficiency, and more importantly, are more beneficial for reducing VOCs by further reducing the amount of solvent in cleaning equipment. Water-based adhesives: Water-based adhesives have been developed using water as the carrier medium instead of solvent. This reduces the weight of the product and eliminates VOC emissions, as well as minimizing fire risk during the process. Water-based adhesives have begun to replace solvent-based systems, particularly in areas such as the bedding industry. Water-based adhesives are also well suited for high-speed application and assembly. These types of adhesives are generally wet-bonding, and therefore at least one of the lower layers must be water-permeable to allow water to pass through the bond line. This explains why water-based adhesives are commonly used for bonding wood, paper, textiles, leather, and other porous substrates. In the case of emulsions, solid fillers are sometimes added to reduce cost and form a putty. These types of adhesives can be used for tile and wall panel bonding and sealant (caulking) purposes. Bio-based adhesives: For an adhesive to be called bio-based, most of its substances such as starch, vegetable oils, resins and lignins must be natural. The use of these substances helps reduce the carbon footprint of products. Bio-based adhesives can compete with synthetic adhesives by improving their strength and water resistance properties through modification with different dispersing agents and cross-linkers. These adhesives, which have different components such as cellulose, proteins, lignins and tannins, are widely used especially for bonding wood products.

5 Types of Environmentally Friendly Adhesives

Renewable raw material-based adhesives offer a wide range of options for conserving resources. Demand for environmentally friendly adhesives, also known as green adhesives, continues to grow, and work on developing such adhesives has been ongoing for years. Renewable adhesives: Renewable adhesives refer to adhesives made from materials such as beeswax and plants and containing no petroleum derivatives in their formulations. These sustainable adhesives not only reduce carbon footprint, but also contribute to the overall sustainability of numerous applications such as paper lamination, carton sealing, and bottle labeling. Recyclable adhesives: A recyclable adhesive can be melted and recollected at the end of its service life without producing any adhesive waste. Recyclable adhesives are commonly used in the automotive industry as well as for bonding glass, aluminum, and steel. Biodegradable sustainable adhesives: Biodegradable adhesives are designed to be broken down by bacteria and other microorganisms. During the decomposition process, water, carbon dioxide, and other natural gases are produced depending on environmental conditions. These adhesives are mainly found in paper and packaging, envelopes, hygiene products, and medical devices. Compostable adhesives: Compostable adhesives belong to the biodegradable sustainable adhesive group. The key difference is that compostable systems break down under specific (compost) conditions. These types of adhesives decompose in industrial and domestic compost environments, and the degraded product is suitable for enriching soil. Compostable adhesives are found in packaging adhesives such as hot melt adhesives and PSA (Pressure Sensitive Adhesives). Repulpable adhesives: Repulpable adhesives, which stand out for their ability to not completely dissolve during paper pulping, are becoming increasingly popular in the paper and packaging industry. Repulpable adhesives used in cardboard boxes, envelopes, and other paper products are among the most sustainable adhesive options. These types of adhesives are completely soluble without leaving any waste. Prepared by: Murat Soygür

Sources

https://www.epa.gov/indoor-air-quality-iaq/what-are-volatile-organiccompounds- vocs https://www.sciencedirect.com/science/article/abs/pii/S0143749621001901 https://www.adhesiveplatform.com/biodegradable-compostable-adhesives/ https://www.adhesiveplatform.com/sustainabi l ity-of-adhesives-andsealants/