Water-resin adhesives

Phenolic Resins. Phenohc resins (qv) are formed by the reaction of phenol [108-95-2] C H O, and formaldehyde [50-00-0] CH2O. If basic conditions and an excess of formaldehyde are used, the result is a resole phenohc resin, which will cure by itself Hberating water. If an acid catalyst and an excess of phenol are used, the result is a novolac phenohc resin, which is not self-curing. Novolac phenohc resins are typically formulated to contain a curing agent which is most often a material known as hexamethylenetetraamine [100-97-0] C H22N4. Phenohc resin adhesives are found in film or solution... 

Pentaerythritol in rosin ester form is used in hot-melt adhesive formulations, especially ethylene—vinyl acetate (EVA) copolymers, as a tackifier. Polyethers of pentaerythritol or trim ethyl ol eth an e are also used in EVA and polyurethane adhesives, which exhibit excellent bond strength and water resistance. The adhesives maybe available as EVA melts or dispersions (90,91) or as thixotropic, one-package, curable polyurethanes (92). Pentaerythritol spko ortho esters have been used in epoxy resin adhesives (93). The EVA adhesives are especially suitable for cellulose (paper, etc) bonding. 

The contact angles of water and adhesive resin on wood are higher in the case of freshly harvested wood compared to stored chips. This means that the surface of particles from this fresh wood is more hydrophobic. This influences the wetting and the penetration negatively and with this the gluability. Reason for this lower wettability of freshly harvested wood is a higher content of some wood chemical components, or wood extractives, as has been determined by water extraction. This result, however, must not be confused with the better wettability of a freshly cut surface, independently if it is freshly harvested or stored wood. 

Water -Absorbing Adhesives 11. Make a resin with a hydrophilic part 16. Invent an adhesive that reacts with water (It is time-consuming and costly in doing research) 20. Use a water scavenger in the adhesive base (comparatively feasible and effective by adding zeolite to the adhesive) 28. Choose a water catalyzed polymer... 

The efficiency of ethylene glycol-water as a delignifying solvent has been demonstrated by Gast and Puls (10). Results showed that sufficiently delignified pulps could be obtained. Also, the lignins produced showed promising results as extenders in phenolic resin adhesives. 

Water-dispersible polyisocyanate compositions containing polyethylene oxide were previously prepared by the authors (2) and used as aqueous resin adhesives. 

This review will first present the metal/epoxy resin adhesive system and discuss how the presence of metal oxides influences adhesion secondly, present the reasons why these systems exhibit very good adhesion strength under dry conditions and why this adhesion strength is greatly reduced in the presence of water thirdly, examine possible methods of increasing their durability in wet environments and finally, discuss some of the spectroscopic techniques that are currently being used to aid in the advancement of metal/polymer adhesion technology. 

MW 92.53 CAS [106-89-8] used to make epoxy resins, adhesives, surfactants, and plasticizers, and also as a solvent for gums, resins, and paints colorless liquid chloroform-like odor boils at 116°C solidifies at-57°C vapor pressure 12 torr at 20°C density 1.18 g/mL at 20°C moderately soluble in water (6.6% at 20°C), soluble in most organic solvents moderately toxic, carcinogenic, and a strong irritant (Patnaik, 1992). 

Water is sometimes used as a solvent for water-soluble resins. Certain epoxy adhesives are available as water-based emulsion or latex formulations. In the early 1970s, during the time of the petroleum crisis, water-based adhesives were thought of as a possible replacement for solvent-based adhesives systems. However, water-based adhesives never met the lofty expectations primarily because of the time and energy required to remove water from the bond line, the corrosion that the water causes in drying ovens, and the poor moisture resistance of cured water-based adhesives. 

Since the oil shortages of the 1970s, there has been a sustained search for materials to replace the petroleum-based resins used as durable adhesives for exterior wood products. Such alternatives are considered important, because supplies of petrochemicals for use in the wood industry could again become undependable. Ideally, the source of material for an adhesive would be readily available, possibly from materials already found near or used by wood processing plants, for example, agricultural or wood-based renewable resources. The purpose of this investigation was to explore the use of carbohydrates as constituents in water-resistant adhesives. 

Lately 185), the hydrogenated HTPBs have been used as an additive for coatings composed of chlorinated resins in order to improve water resistance, adhesion, and stability. 

Water based adhesives (resin extender, thickener)... 

Self-adhesive labels can be applied to most materials wood, plastic, metal, glass, paper and board. As the adhesives are resin-based (plasticised thermoplastics), migration problems can occur when they are applied to certain plastics (PVC, LDPE, etc.). Adhesive systems for pressure sensitive labels include latex and acrylic bases and adhesives which may be applied as a hot melt, or via a solvent, emulsion or dispersion base. Water-based adhesives are currently increasing in use. 

Neotac. PQ Resins] Water-borne adhesive polymers. 

Orzan . ytmier] Lignosulfonates binder, diqmsant, emulsifier, suqiend-ing agent fnr aq alt, gypsum board, sl, leadier, metalluigy, briquetting, resins, adhesives, pesticides, water treatment, ore flotation. 

Amino resins Water-soluble adhesives Bonding of layers in plywood and the bonding of particles in particle board... 

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