Compatibility of nonacidic waterborne preservatives with phenol-formaldehyde adhesive

Abstract

Thirteen nonacidic waterborne preservatives were in­ vestigated for their compatibilitywith phenol-formaldehyde adhesive on aspen veneer treated with the preservatives to retentions of 0.2, 0.4, and 0.6 pcf. Of these preserva­ tives, didecyl dimethyl ammonium chloride (DDAC), DDAC with copper, DDAC with carbamate (DDACCA),sodium fluoride,and ammonium hydrogen difluoridedid not inter­ fere with adhesion at any retention level. Carbamate in the DDACCA preservative apparently reinforced inter­ facial regions of the bondline to produce bond strengths much higher than those of untreated controls, particularly at the higher retentions. Ammoniacal copper zinc arsen­ ate at 0.2 pcf retention did not interfere with adhesion, but at higher retention levels bond integrity was below standards. All three borated preservatives that were stu­ died caused poor bonding, even at the lowest retentions. Emulsions of copper naphthenate, copper octoate, and zinc naphthenate also caused poor bonding. Determination of wet wood failure after vacuum-pressure soaking was more effective in detecting adhesion incompatibility than de­ termination of dry shear strength and wood failure after multiple cycles of vacuum-pressure soaking and drying.