Blend glue

Table 5 Low-Blood-Content Soybean Blend Glue Ingredients and Mixing Procedure... 

The formulation of the typical soybean-casein blend glue listed in Table 7 is quite different from any protein adhesive described thus far in that all ingredients, dispersing... 

Since soybean blood blend glues were covered in the preceding section, in this portion of... 

Blood and soybean-blood blend glues of appropriate high viscosity and granular consistency can be pressed cold according to the schedule shown for soybean glues. For this purpose they must contain a terminal addition of about 5% preservative based on dry glue weight in order to meet product standards for mold resistance [24]. 

CASEIN AND PROTEIN BLEND GLUES AS WOOD ADHESIVES... 

Table 10. Formulas for Casein and Casein-Blend Glues (Dry Mix Type). ...

The formulas given in Table 10 are for the dry mix type of casein and protein blend glues which are currently in use in the United States. Several decades ago, the practice of formulating these glues as wet mixes was widespread, an approach which made a wider range of additives available. Frequently a phenolic resin... 

The recommended latex for use with both casein and protein blend glues is a carboxy-lated styrene-butadiene, with a styrene content of 60 to 65 %. When this latex has a pH of 7.5-... 

The casein wood glues have a long history of use as interior structural adhesives, assembly adhesives, and panel-to-frame adhesives. A limited but important use is as a nonconductive adhesive in the construction of spacers for the large transformer boards for the electrical industry. The most popular use of casein and protein blend glues is in the production of hollow and solid core flush doors, an operation for which these glues are ideally suited. Most of the doors in this country are made with this type of glue. 

Flush doors are produced by bonding skins of plywood, hardboard, or particle board to the vertical and horizontal frames (the stiles and rails), which are usually either a soft wood such as fir or a man-made product comprising layers of pressed board. Hollow core doors utilize an accordion-type paper core, while a solid core door is constructed with a core of pieces of scrap wood edge-glued with an inexpensive casein-soy glue. Some of these cores are held to shape by corrugated cardboard, which is bonded to their surfaces with the same type of protein blend glue. 

Fire doors are usually constructed by bonding plywood to a frame of fire-retardant-treated stiles and rails, made with either hard maple or a man-made hardboard, this frame having been fastened around a fire-resistant mineral core. Casein and casein-soy blend glues with and without the furfuryl alcohol additive are the primary adhesives currently selected for use in these operations. 

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