What role does glue play in multilayer boards?

 The production of engineered wood products is inseparable from adhesives, and the environmental friendliness of the adhesives directly affects the environmental friendliness of the finished boards. Taking plywood as an example, what are the effects of different adhesives on the boards?

The adhesives used in engineered wood products have a history of thousands of years in China. From the original bone glue to the later urea-formaldehyde glue, the bonding strength of the adhesives has been continuously improved through the continuous research of generations. However, the side effects have also increased.

Regarding the adhesives currently available on the market, different adhesives have completely different effects on the quality of engineered wood products.

Firstly, urea-formaldehyde resin, the cheapest and most polluting adhesive on the market, is composed of formaldehyde and urea through a chemical reaction. Initially, the ratio of formaldehyde to urea was approximately 3:7 or lower. Low formaldehyde content resulted in less environmental pollution, but the bonding strength of the boards was not very strong. Therefore, some companies and vendors increased the formaldehyde-to-urea ratio, increasing the formaldehyde content and thus enhancing the bonding strength, but also significantly lowering the environmental protection rating of the engineered wood products.

Taking multi-layer boards as an example, after using high-quality veneer and highly polluting urea-formaldehyde glue in production, their environmental protection level cannot reach the E1 level at all, which means it cannot reach the current minimum level.

Not only urea-formaldehyde resin, but also phenolic resin and melamine resin, which are collectively known as three-aldehyde resins, will lower the environmental protection level of the boards and become a source of indoor pollution.

Therefore, to solve this problem, protein glue has emerged on the market. Soy protein glue is made from edible-grade soybean flour and water, through physical mixing. It contains no formaldehyde, benzene, or other harmful substances, and during production, it can neutralize some of the formaldehyde content in the wood itself. Therefore, the environmental protection level of finished multi-layer boards is significantly improved. It can reach the CARB certification NAF level, which is the highest level internationally. Currently, the domestically produced Yimeikang formaldehyde-free multi-layer board is the most advanced.

As for other adhesives on the market, such as MDI, when used in the production of multi-layer boards, they can help the multi-layer boards reach the E0 level. The E0 level standard is: formaldehyde emission less than or equal to 0.5mg/L. According to scientific surveys, when the amount of E0 grade adhesive used indoors is too large, it will lead to excessive indoor formaldehyde levels.

Different adhesives have different effects on plywood or other engineered wood products. Merchants and homeowners can inquire about the type of adhesive used in the boards to determine their environmental protection level and whether their use in indoor home furnishings will cause formaldehyde levels to exceed the standard.

Is it better to use highly polluting building materials that harm your family's health, or to choose environmentally friendly building materials to purify indoor formaldehyde?