Environmental Project, 942 – Substance flow analysis of resorcinol

Substance Flow Analysis of Resorcinol

6 Alternatives / substitutes

6.1 Wood adhesives
6.2 Rubber adhesives
6.3 Hair dyeing products
6.4 Other applications

6.1 Wood adhesives

Resorcinol and phenol-resorcinol-formaldehyde glues are primarily used as special purpose adhesives in the wood industry, being more expensive than other glues. They are not widely used for plywood manufacture. Rather, they are used as assembly glues in solid wood products, which must resist exposure to the weather and to water, such as glued laminated wood beams and forklar I-joints (Eckelmann, n. y.).

The properties of resorcinol are high in both dry and wet strength. They are very resistant to moisture and damp conditions, and more resistant to high temperatures and chemical ageing than wood. They cure at room temperatures on most species of wood.

The United Soybean Board (USB) – an interest organisation for US soybean farmers - have established a market opportunity summary for soy-based wood adhesives. Based on research at Battelle, two segments/applications for wood adhesives containing resorcinol have been identified as emerging markets for soy-based adhesives. One application is glue-laminated lumber with a thickness of 2 inches or less. The other is I-joists, load-bearing structural members consisting of a top and bottom flange adhered to a vertical web made of OSB (oriented strand board) or plywood. In both cases, soy-based glues can be used as extenders to the resorcinol-containing glue. According to USB, a system with hydrolysed soy protein and phenol-resorcinol-formaldehyde will achieve faster cure rates and improved economics. From a health and environmental point of view, substituting either element in a phenol-resorcinol-formaldehyde glue is seen as advantageous, as there are no significant impacts associated with soy protein. It is however remarked, that the glue will still contain the elements, the only difference being that smaller amounts are used in the glueing process.

There is no information regarding Danish or European investigations of the possibilities of using soy protein for the above (or similar) applications.

6.2 Rubber adhesives

The use of resorcinol as an adhesive in production of rubber products like tires and conveyor belts can only be mapped to a very limited degree. It is assumed that it is used in its pure form or in combination with for example silisic acid and hexamethylentetraamin to obtain good adherence to steel cord in tires (Ahlbom and Duus, 1994).

Traditionally, the rubber industry is rather secretive about its chemicals, manufacturing processes and products. There is little doubt that resorcinol can be substituted in many products, but the substitutes are virtually unknown. The US EPA thus states in a report on presumptive maximum achievable control technology in the rubber tire manufacturing source category that “… the tire manufacturing industry has indicated that tire manufacturing processes are, in large part, proprietary in nature. In particular, different companies use different formulas in the manufacture of tires. Types and quantities of materials, including solvents, vary, and are closely-guarded trade secrets…” (US EPA, 1998).

6.3 Hair dyeing products

Resorcinol was found in 15 out of 18 hair dyeing products on the Danish market in concentrations from 0.002 to 1.3 %. It is used as a coupler in the colouring system, but it has not been possible to determine the function of resorcinol more precisely in the current study. It has not been possible to find information on possible substitutes.

6.4 Other applications

Alternatives for and substitution of resorcinol in other applications is not discussed here.