Formaldehyde-Free Resins for the Wood-Based Panel Industry: Alternatives to Formaldehyde and Novel Hardeners

Abstract

Due to its carcinogenic properties, the presence of formaldehyde in resins and other industrial products has been a subject of great concern in recent years. The presented review focuses on modern alternatives for the production of wood-based panels; i.e., substitutes for formaldehyde in the production of amino and phenolic resins, as well as novel hardeners for formaldehyde-free wood adhesives. Solutions in which formaldehyde in completely replaced are presented in this review. Recent advances indicate that it is possible to develop new formaldehyde-free systems of resins with compatible hardeners. The formaldehyde substitutes that have primarily been tested are glyoxal, glutaraldehyde, furfural, 5-hydroxymethylfurfural, and dimethoxyethanal. The use of such substitutes eliminates the problem of free formaldehyde emission originating from the resin used in the production of wood-based panels. However, these alternatives are mostly characterized by worse reactivity, and, as a result, the use of formaldehyde-free resins may affect the mechanical and strength properties of wood-based panels. Nonetheless, there are still many substantial challenges for the complete replacement of formaldehyde and further research is needed, especially in the field of transferring the technology to industrial practice.

Wooden door preferences based on lifestyle theory and consumer behaviour theory

“…Therefore, wooden door enterprises need to pay attention to the changes in the market, proactively change the original production methods, the use of green production materials, and environmentally friendly production processes (Xiong et al 2020). In recent years, the market has seen the use of aldehyde-free decorative paper, aldehyde-free wood panels, aldehyde-free glue, and other aldehyde-free environmentally friendly materials to produce wooden doors favoured by consumers (Chrobak et al 2022). With the depth of research and development in recent years, problems such as high cost, poor mechanical properties and difficulty in construction of water-based paints have been solved one by one, and their green and environmentally friendly characteristics are gradually accepted by the market and welcomed by consumers (Yan and Peng 2021).…”

A dialdehyde starch-based adhesive for medium-density fiberboards

“…Every year, the wood industry uses approximately 11 million tons of these adhesives worldwide (Pizzi et al 2020). Formaldehyde, however, is harmful at higher concentrations and is classified as a "probable human carcinogen" (Chrobak et al 2022). More restrictive regulations have been enacted during the last years on the emission of free formaldehyde from wood-based products.…”

Lignocelluloses-Based Furan-Acetone Adducts as Wood Adhesives for Plywood Production

“…Lignin [ 7 , 8 , 9 ], tannins [ 10 ], proteins [ 11 , 12 ], and starch [ 13 , 14 ] have been evaluated as raw materials to synthesize the substitutes for existing thermosetting adhesives. Similar to starch, polysaccharides such as cellulose and hemicelluloses are renewable feedstocks for the preparation of bio-based wood adhesives [ 15 , 16 , 17 , 18 ] due to the advantages of being abundant, inexpensive, and environment-friendly. However, the use of cellulose or hemicelluloses to prepare wood adhesives is rarely reported, mainly because cellulose and hemicelluloses do not show any adhesion properties, even at high temperatures.…”