UFR Urea-formaldehyde (UF) resins are dominantly used in the medium density fiberboard (MDF) industry because of their low cost and fast curing characteristics.

UF resin is a none-transparent thermosetting or plastic, made from urea and formadehyde heated in the presence of a mild base such as ammonia or pyridine. These resins are used in adhesives, finishes, MDF, and molded objects. Urea-formaldehyde resin's attributes include high , flexural modulus and heat distortion temperature, low water absorption, mould, high surface hardness, elongation at break, and volume resistance.

Dissolving the Powder Resin:

The resin is mixed with water in good agitation using a mechanical stirrer,until all resin mixes to becomes a homogenous suspension. The water temperature 20-30 is most suitable.

Recommended Glue Mix for MDF application:

resin: 100 part by weight

Water: 84.5-86.5 part by weight

Urea: 45-47part by weight

Properties of Glue Mix:

Viscosity/30: 60-90cps

PH/30: 7.5-8.5

Sg/30: 1.22-1.40

Soild Content:58-60%

Reactivity/100: 80-120 sec

Free Formaldehyde: 0.35-0.55%

Mixing Procedure:

Charge about 4/5 of the required water in to the mixer and start agitation

Pour all the resin slowly and mix till all powder dissolve, no lump,

Charge all calculated urea, after all material has been dissolved, pour the remaining water

Hardener:

Commonly used are Ammonium Salt, ie. Ammonium Chloride.

Standard level are 1-2% solid on dry glue, but local and current requirement need asjustment, such as pH,moisture of fiber or emission level of the board.

Wax Emulsion:

A suitable wax emulsion may be need for improving the water resistence and dimensional stability of the board, the usually dosage level is 0.5-1% solid on dry fiber weight.

The emulsion can be spray directly to the fiber or a compatible one if for mixing with the resin.

Glue Application:

The resin is spray directly to the fiber either by batch or continous running in static mixer, the normal level are 6-16% resin solid on dry fiber, depend of the board thickness.

Pressing Conditions:

The optimum pressing speed or time and temperature can only be determined by practical trials base on the standart of the plant. It also depends on press system such as Conti-roll, multi or single daylight, the fiber pH,moisture,glue reactivity, amount of hardener,thickness and density of finish board.

Storage:

In the original bags at 30 and good ware house condition resin has storage life up to one year. The product should always be protected from high temperature, high humidity and water.