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Knowde Enhanced TDS
Identification & Functionality
Applications & Uses
UF-RW25 is a neat urea resin powder that is suitable for a variety of adhesive applications including cellulosic substances, wood bonding and foundry sand binder. The user can blend the resin with water, apply it, and then cure the resin with only heat or increase the cure rate by adding a catalyst. Amounts of catalysts can be added to yield a cold curing UF resin if needed. Initially the glue line, using neat UF-RW25, is white. The glues color and texture can be changed by adding wood flour, shell flours, and extension of the blend by adding wheat flour. Advantages of using this powder, over a typical cold cure Urea Formaldehyde resin are:
- Special packaging to prevent curing due to moisture acting on the catalyst is not needed. A three ply paper - polylined bag is used to hold the resin. The resin can be shipped almost anywhere in the world without losing its activity.
- The customer can use only heat and pressure to cure the resin or add varying amounts of catalyst to increase the cure rate to match their process.
- Enough catalysts can be added to yield a cold cure UF resin.
- The customer has more control over UF approved additives and colorants to meet their needs. 5. Extension of the glue mix is possible using wheat flour in portions typically used by the wood industry.
Place two thirds of the water in the mixer and begin stirring. Add 50 pounds of UF-RW25 powder resin rapidly but evenly to avoid lumping. When the mix is smooth, add the remaining water. The user can vary the water charge from 25 to 35 pounds to adjust the viscosity for the type of glue spread needed for the wood used. More absorbent woods need glue blends with less water. About five to ten pounds of wheat flour can be added to a glue blend using 50 pounds of dry UF powder. The wheat can be added slowly after the UF solution is smooth.
In a neat UF resin solution the UF-RW25 will be usable for one to three days. The best way to store the liquid is in a cool area with a cover on the container to prevent water loss by evaporation and contamination of the blend. When catalysts are added, an un-extended blend will be good for about five hours. More water cannot be added to thin the solution out when the catalyzed UF glue is thickening. Starch additives will reduce the water resistance performance of the glue. Adding about 3% to 6% wood flour or shell flour will usually improve water resistance.
The most water-resistant qualities of UF-RW25 develop when pressure is applied to the glue line.
Typical pressures are:
|Light density woods||100 - 150 psi|
|Medium density woods||150 - 225 psi|
|High density woods||200 - 300 psi|
|Value||Units||Test Method / Conditions|
|Particle Size (Retained on 40 Mesh)||max. 0.5||%||TM-610D|
|Gel Time (at 100°C)*||50 - 100||sec||TM-649|
|Viscosity (at 25°C)*||500 - 2000||cps||TM-655|
|Pot Life (at 25°C)*||2 - 5||hours||TM-649|
* - For gel time, viscosity, and pot life; mix 4 grams of ammonium sulfate with 130 grams water and 200 grams of powder resin.
Packaging & Availability
The standard package for UFRW-25 is a multi-wall paper bag having a net content of 40 lbs. or 55 lbs., and a 100 lb. or 300 lb. fiber drum.
Storage & Handling
UFRW-25 is sensitive to heat and humidity and should be stored in a closed container in a cool, dry area. Avoid direct contact with concrete floor. Optimum storage conditions are below 75°F. and 60% relative humidity.