Water content glue

Glues chosen for use in bonding material with low absorbency and permeability should not have high carrier (especially water) content. High-carrier glues require suflScient assembly time ( preferably open assembly) to allow for dissipation of most of their carrier. A better option would probably be to use solvent solutions of polymer compatible with the consolidant. 

In early work on plastic-impregnated wood, it was found that traditional water-based wood glues could be used, especially the hot-setting ones 18, 19), However, longer assembly times, which allowed reductions in glue-film water content before clamping, led to improved results. 

The water content of the high-blood-glue formulation is much larger, which offsets most of the material eost inerease. This is possible because the water... 

The best striking qualities are obtained by use of very high grade glue (such as Peter Cooper Grade 11a extra with foaming properties), leading to a match paste of d--1.20-1.35 at a water content of 30-32%. 

Water dispersed, solvent free, synthetic glue with low water content ... 

The use of defatted peanut meal in plywood glues has been reported in the United States and India (40,103,104,129,156,157). Peanut meal, which has a minimum of 50% protein content and a nitrogen solubility of at least 70% in 1 M sodium chloride, is satisfactory for making water-resistant glues. 

Cyanoacrylate adhesives (Super-Glues) are materials which rapidly polymerize at room temperature. The standard monomer for a cyanoacrylate adhesive is ethyl 2-cyanoacrylate [7085-85-0], which readily undergoes anionic polymerization. Very rapid cure of these materials has made them widely used in the electronics industry for speaker magnet mounting, as weU as for wire tacking and other apphcations requiring rapid assembly. Anionic polymerization of a cyanoacrylate adhesive is normally initiated by water. Therefore, atmospheric humidity or the surface moisture content must be at a certain level for polymerization to take place. These adhesives are not cross-linked as are the surface-activated acryhcs. Rather, the cyanoacrylate material is a thermoplastic, and thus, the adhesives typically have poor temperature resistance. 

The moisture content of the glued particles is the sum of the wood moisture content and the water which is part of the applied glue mix. Therefore, the moisture content of the glued particles mainly depends on the gluing factor. Usual moisture contents of glued particles are 6.5-8.5% in the core layer and 10-13% in the face layer for UF, and 11-14% in the core layer and 14-18% in the face layer for PF. 

The contents of the bag are subjected to ebullition for a second and a third time, and by this means afford sine. When tho resulting solutions are too dilute for either glue or size, they are employed instead of water for extracting the glue from froeh materials the refuse in tho bags, after all available matter has been extracted, is sold for manure, and every particle of animal substance is turned to account. 

The treated veneer should then be close piled for one to two days, with a water proof cover over it, to allow for equalization of the resin content by diffusion. The veneer can then be dried and the resin polymerized in a continuous veneer drier or in a dry kiln. Real fast initial drying should be avoided to prevent excessive migration of the as yet uncured resin to the surfaces. The treated veneer is then laminated into panels of any desired thickness in a hot press using phenolic glue (45). 

The many different types of adhesives and the wide variety of ways in which they can be used influence the potential for migration of chemicals into the packaged food. This then helps to provide a framework for subsequent considerations of specific applications. The two main parameters considered are the surface area of adhesive used and the residual content of low molecular weight substances. Taking surface area first, there clearly is a quantitative difference between small spots or strips of adhesive used at ends and seams to fabricate cartons and pouches or used to attach small sticky labels, compared to an adhesive used to glue whole sheets of materials together to make a laminate. As regards composition, for solvent-based, water-based heatseal... 

---