Phenolic dispersion

Phenolic Dispersions. These systems are predominantly resin-in-water systems in which the resin exists as discrete particles. Particle size ranges from 0.1 to 2 p.m for stable dispersions and up to 100 p.m for dispersions requiring constant agitation. Some of the earliest nonaqueous dispersions were developed for coatings appHcations. These systems consist of an oil-modified phenoHc resin complexed with a metal oxide and a weak solvent. 

Phenolic dispersions, production of, 18 768-769 Phenolic effluents, ozone oxidation of,... 

Several hybrid epoxy emulsions have been commercially prepared. An epoxy emulsion blended with waterborne aliphatic urethanes exhibited peel strength on aluminum of 10 lb/in—1.5 times greater than with the polyurethane itself. The optimum concentration of urethane in the final emulsion was about 50 percent by weight.13 Epoxy-phenolic dispersions have also been developed to provide waterborne adhesive systems with high glass transition temperature and chemical resistance. 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

Union Carbide Corp. "Phenolic Dispersion BKUA-2370," Product Information, F-47415, 1979. 

Phenolic tackifiers (106) in the form of dispersions can be used to formulate neoprene or acrylic latex into waterborne contact adhesives. For example, a solid ratio of latex and phenolic dispersion (Union Carbide-BKUA-2370 or BKUA-2260)of 3 1 can form a stable adhesive at pH 6.0-6.5. 

Acrylic latex/phenolic dispersion (2/1) Canvas to cold rolled steel 35 (20) [35]... 

Phenollcs. Introduced in the early 1900s, phenolics were the first commercial synthetic resins. They are available as 100% phenolic baking resins, oil-modified, and phenolic dispersions. Phenolic resins, used as modifiers, will improve the heat and chemical resistance of... 

Aqueous dispersions are used in fiber bonding, paper coating, friction and abrasive applications, and laminates and wood bonding. Phenolic dispersions improve the strength of latex-contact adhesive applications. Epoxy-modified phenolic dispersions are prepared by dispersion of the phenolic epoxy resin. The systems are used for baked primer applications and bonding requirements. Minimum baking conditions are 20 min at 150°C (26). 

Waterborne contact adhesives contain an elastomer in latex form, usually an acrylic or neoprene-based latex, and a heat-reactive, cross-linkable phenolic resin in the form of an aqueous dispersion. The phenolic resin improves metal adhesion, green strength, and peel strength at elevated temperature. A typical formulation contains three parts latex and one part phenolic dispersion (dry weight bases). Although metal oxides may be added, reaction of the oxide with the phenolic resin does not occur readily. 

MWNTs have been used as dispersed CNTs and network CNTs as reinforcements of phenolic matrices. Composite phenolic-dispersed CNTs were fabricated through the melt mixing method, which may lead to the agglomeration of CNTs in the matrix and introduce defects in composites. The infiltration of the resin into the network CNT generated composites with better mechanical properties when compared to the dispersed CNTs because the CNTs in the network are longer and contain fewer agglomerates and defects (Tai et al, 2004). 

This factor can be defined for slightly ionized phenol dispersions, i.e. at pH values under 8. If the phenols are ionized, an apparent coefficient is measured such that ... 

Stable blends of UCAR Acrylic Latex 152 and phenolic dispersion BKUA-2260 were prepared by preneutralizing the acrylic latex with ammonia and adding the phenolic. Acetone-water solutions of acrylic-CK-1834 phenolic were prepared by adding the acrylic latex to an acetone solution of CK-1834 at the level necessary to yield a 15% solids solution. Indicated surfactants were then added to this solution. Metal adhesion samples were assembled wet and peel tested at 2"/tnin. after 1 week of drying at room temperature. 

Microscopic studies of acrylic/phenolic dispersion blends show the phenolic particles dispersed in the acrylic matrix. This and the data of Table 1 suggest at least three possible mechanisms for green strength enhancement. 1) The phenolic particles may be serving merely as fillers to improve the wet strength of the system. 

Open Time-Pressure Latex Phenolic Dispersion A Phenolic Dispersion... 

Substrate Acrylic Latex/ Phenolic Dispersion A Acrylic Latex/ Phenolic Dispersion Neoprene Latex/ Phenolic Dispersion B ... 

Phenolic Dispersion Particulate Nature and Molecular Weight. Phenolic dispersions of the BKUA-2260 type are solvent free, gum arabic stabilized dispersions of heat reactive resins prepared from the condensation of formaldehyde with variously substituted phenolic monomers. A typical set of properties is shown in Table 4. 

The acrylic/phenolic contact adhesive systems discussed above do not contain an organic solvent. However, the Tg of the phenolic BKUA-2260 in these systems was found to depend on residual water. Table 6 shows how the Tg changes during a drying program for two phenolic dispersions which differ only in gel time. Figure 2 shows the relationship between water and Tg for the same two dispersions. For the dispersion with 140 sec. gel time, the Tg is 32°C when dry and near 10°C with 3% water. (Fox equation predicts Tg = 18°C for 3% water, assuming Tg [water] = -146°C and Tg [BKUA-2260] = 32°C). 

We wish to acknowledge discussions with and the assistance of Drs. N. J. McCarthy and 0. Olabisi in respectively supplying the samples of phenolic dispersion and the modulus-temperature data. 

Recently, phenolic dispersion in water has been described to eliminate environmental prob-lems. In such cases the same types of resins mentioned above can be used. The advantage of dispersed resins as compared to water-soluble resins is that they are higher in molecular weight than the latter and have little or no free-phenol content. The basic curing mechanisms in these systems are the same as those mentioned earlier. 

PEG-6 tridecyl phenol dispersant, emulsification/dispers-ibie PVAc... 

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