Soy Flour Substitution in Polymeric Diphenylmethane Diisocyanate Resin Reduces Press Platen Sticking*

Abstract

Partial (10% to 30%) substitution of soy flour in polymeric diphenylmethane diisocyanate (pMDI) resin substantially reduces platen sticking during hot-pressing of particle mats. Adding the soy flour to a fixed dose of pMDI (instead of substituting it) reduces platen sticking to an even greater extent. The soy decreases the tack of cured pMDI, thereby reducing the propensity of resinated particles to transfer to the platen. The tack reduction effect of soy on cured pMDI contrasts with its effect on uncured pMDI, where the cold tack is increased.

Soy-Flour Adhesive Bonding of Low-Moisture Hickory and Red Oak Veneer

“…Soy-flour adhesives do not usually exhibit sticky tack properties seen with other woodbonding adhesives but resemble wet plaster or cement in their flow characteristics. Asafu-Adjaye et al (2022) determined that cold tack of pMDI increased with partial substitution with soy flour to the level obtained with urea formaldehyde resins while providing significant cost reduction. However, a reduction in platen sticking during hot pressing was found when adding soy flour to the given amount of pMDI as well as when replacing part of the pMDI by soy flour; both addition or replacement were up to 30 percent of the amount of pMDI, and the stronger effect was given with the replacement (Asafu-Adjaye et al 2022).…”