Urea-formaldehyde resins properties

Amine hydrochloride catalyst for urea formaldehyde resins Properties ... 

We recently have received a memorandum from a customer who buys our formalin indicating that there are periodic problems, mostly in the summer, with the formalin they are receiving from us. They claim that the formalin contains unacceptably high amounts of formic acid relative to formaldehyde. It seems that this alters the urea-formaldehyde resin properties such that the particle board and plywood subsequently manufactured do not have the appropriate tensile and load strength. They are threatening legal action unless this problem is rectified immediately. 

Foams prepared from phenol—formaldehyde and urea—formaldehyde resins are the only commercial foams that are significantly affected by water (22). Polyurethane foams exhibit a deterioration of properties when subjected to a combination of light, moisture, and heat aging polyester-based foam shows much less hydrolytic stabUity than polyether-based foam (50,199). 

Electrical properties, which are initially similar to those of urea-formaldehyde resins, are maintained better in damp conditions tmd at elevated temperatures. 

Urea-formaldehyde resins are used as the main adhesive in the forest product industry because they have a number of advantages, including low cost, ease of use under a wide variety of curing conditions, low cure temperatures, water solubility, resistance to microorganisms and to abrasion, hardness, excellent thermal properties, and a lack of color, especially in the cured resin. 

Dost in 1971 reported on a study where redwood bark fiber was used in three-layer particleboard (44). Amount of bark in the furnish, by weight, was 0, 10, 20, and 30% hammemilled disk flakes or Pallmann flakes of redwood wood made up the remainder of the furnish. Urea formaldehyde resin was applied at three percentages. Test results showed surface smoothness and strength properties (MOR, MOE, and IB) decreased with increasing bark content in the boards. Water absorption decreased, but thickness swelling and linear expansion increased as the amount of bark increased. 

Oligophenylethoxysiloxanes are used as modifiers for various polymers to improve their weather resistance and other technical characteristics, as well as to increase the heat resistance of coatings. E.g., PES-50 is used to modify polyethers, aciylic and epoxy polymers PES-80 is used to modify alkyd and urea-formaldehyde resins. Besides, PES-80 is used as an additive in paints and enamels (to improve their flow properties, gloss and colour), as well as in concrete mixes (to improve the water resistance and durability of concrete works). 

While catalysts are also used in the production of other types of polymers, the properties of most of these materials are not particularly dependent on the type of catalyst employed. Many poly condensation reactions, e. g. the formation of polyesters, polyamides or urea-formaldehyde resins, are speeded up by addition of some Bronsted or Lewis acids. Since relevant properties of these polymer products, such as their average chain lengths, are controlled by equilibrium parameters, primarily by the reaction temperatures and molar ratios of the monomers employed, and since their linkage patterns are dictated by the functional groups involved, addition of a catalyst has little leverage on the properties of the resulting polymer materials. 

Bliznakov, E.D., White, C.C., and Shaw, M.T. (2000). Mechanical properties of blends of HDPE and recycled urea-formaldehyde resin. J. Appl. Polym. Sci. 77,3220-3227. 

CNC REZ K is a modified ethylene urea formaldehyde resin which was created to give the finisher a thermosetting resin which possesses all of the outstanding features of cyclic resins as to shrinkage control, crease resistance, hand appeal and also not detract from soil release properties. This resin gives fairly soft hand on all classes of fibres and is exceptionally durable on the polyester/cotton blends. 

Molded articles from cellular polysulfone, coated with polystyrene, epoxy resin, or vinyl resin, are reported to have improved hardness and surface rigidity. They can also be used as insulating or packaging materials, or, when modified with urea-formaldehyde resin, as flowerpots that are permeable to air and water. These foams have excellent selfextinguishing and low anoke-generating properties (21). 

The author has found the carbohydrate binders (e g. starch, dextrin) superior to phenol formaldehyde resins, maleic and phthalate type resins, polyester, glyptal resins, shellac, vegetable rosins, urea formaldehyde resin and melamine resin in all experiments to date. Dextrins and starches combine good binding properties and low cost with simple handling requirements. 

Chem. Descrip. Butylated urea-formaldehyde resin in n-butanol solv. Uses Crosslinking agent for wood and metal coatings Features Exc. compat. with other resins provides good durability, hydrolytic stability, film flexibility 0.5% max. free formaldehyde Properties APHA 30 max. color dens. 8.75-8.95 Ib/gal vise. (Gardner-Holdt) X-Z3 flash pt. (PMCC) 85 C 94-98% solids Resin 1265-M-70 [Ranbar Tech.]... 

Properties Wh. cryst. solid m.w. 158.09 m.p. 155-165 C Uses Intermediate for dyestuffs for cotton/polyester blends metallic salts as light/heat stabilizers and for antifouling agents in paints catalyst for urea-formaldehyde resins... 

Synonyms Methylated urea-formaldehyde resin Poly (urea-co-formaldehyde), methylated Classification Formaldehyde copolymer Properties Colorless liq. dens. 1.217 flash pt. > 110 C ref. index 1.4840 (20 C)... 

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