11 августа, 2015 
Malyar The guiding principles for the preparation of plywood adhesive glue mixes are:
1. To maintain the highest possible phenolic solids content in the mixed glue (preferably in the range 30 to 40%).
2. To incorporate a cellulosic filler, such as a nutshell flour of 200 mesh or finer, in a proportion of about 20 to 40% of phenolic solids. Nonabrasive inorganic fillers may also be satisfactory.
3. Alternatively, to add about half this amount of unrefined starchy material, such as wheat flour.
4. To add no alkali, or at the most only 1 to 2% to disperse and stabilize the starchy material.
5. To add only enough water to produce a glue viscosity that can be handled by the gluing equipment. The preferred viscosity range is 1500 to 2500 cP, measured at 25°C.
6. To ensure proper wetting of the veneer by the glue film, a surface active agent should be added (about 0.1 to 0.25% of resin solids).
Examples of glue mixes incorporating these principles are listed in Table 1.
|
Material |
Composition |
||
|
40-45% Solids PF resin |
100 |
100 |
100 |
|
300-Mesh coconut (or walnut) shell flour |
12 |
14 |
10 |
|
Industrial wheat flour |
6 |
— |
— |
|
50% Sodium hydroxide |
2 |
— |
— |
|
Surfactant |
0.1 |
0.1 |
0.1 |
|
Water |
10 |
5 |
|
|
Total parts |
130.1 |
119.1 |
110.1 |
|
Phenolic solids |
31-35% |
33-38% |
36-41% |
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