Phenol-formaldehyde resin solution

In the meantime another development had decisively altered the outset situation plastics had been discovered and synthesized, among them also some acid-stable ones such as phenol-formaldehyde resin or poly(vinyl chloride) (PVC). These opened up new possibilities cellulose papers could be impregnated with phenol-formaldehyde resin solution and thus rendered sufficiently acid-stable, and sintered sheets from PVC powder were developed. Independent separators producers were founded, combining knowledge of the chemical industry with experience of the battery industry and thus accelerating the development process. 

Aqueous phenol-formaldehyde resin solution k3.5% solids)... 

Ymyl chloride-aaylic acid copolymer and epoxy resin latices and a phenol formaldehyde resin solution were used to modify sand-cement mortars at room tanperature. The compression strength increased with an increase in the latex/resin concentration and with the addition of calcium chloride or calcium carbonate and a superplasticiser. Tensile and flexural strengths also increased with polymer incorporation. The porosity of the modified mortars decreased with the addition of resin. The percentage of water absorption and acid solubility decreased for the latex/resin modified samples. 21 refs. INDIA... 

A voluminous, highly porous, special paper of cotton linters, or other premium a-cellulose fibers is passed through an immersion bath of aqueous phenol-formaldehyde resin solution and dried. A different process combines the production of the paper directly with its impregnation. Common to both processes... 

Acid Curing. Urea-formaldehyde resins and resol-phenol-formaldehyde resins can be acid-cured by wastes from the production of maleic anhydride [1902]. The waste from the production of maleic anhydride contains up to 50% maleic anhydride, in addition to phthalic anhydride, citraconic anhydride, benzoic acid, o-tolulic acid, and phthalide. The plugging solution is prepared by mixing a urea-formaldehyde resin with a phenol-formaldehyde resin, adding the waste from production of maleic anhydride, and mixing thoroughly. 

P. P. Galchenko, A. P. Titareva, L. G. Kalashnik, and V. D. Krupenko. Plugging solution—contains phenol-formaldehyde resin. 

B. S. Lyadov. Polymeric solution for isolation of absorption strata— contains urea-formaldehyde and/or phenol formaldehyde resin and lig-nosulphonate. Patent SU 1730434-A, 1992. 

V. B. Zhukhovitskij, M. I. Kolomoets, and A. M. Zagrudnyj. Polymeric plugging solution contains urea-formaldehyde resin, expandable resol-phenol-formaldehyde resin containing surfactant and aluminium powder, and maleic anhydride production waste. Patent SU 1728473-A, 1992. 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

As aqueous solution, it is used as a parent compound for preparation of numerous chemicals used in industry, such.as in the manufacture of explosives, plastics, resins (eg phenol-formaldehyde resins) etc (See... 

In this solution, the volume of phenol-formaldehyde resin exceeds 1,250 million pounds per year. Most plywood adhesive resins are shipped in bulk quantities of 4,000 to 10,000 gallons via tankwagon or tankcar to the plywood mills and stored in storage tanks. Other ingredients are collected in a glue mix area and combined with adhesive resin. 

The first synthetic polymers to be of any use were the phenol formaldehyde resins of which the most famous, Bakelite, was discovered by Bakeland at the turn of the century. He combined phenol and formaldehyde in acid solution and got a reaction that starts like the bisphenol A synthesis. 

In aqueous alkaline solution, phenol reacts with formaldehyde (methanal) at low temperatures to form a mixture of 2- and 4-hydroxy-benzyl alcohols. This hederer-Manasse reaction is another example of electrophilic attack which results in the formation of a new C-C bond. The mechanism is illustrated in Scheme 4.14. These products readily lose water to form quinomethanes (methylenecyclohexadienones), which react with more phenoxide. This process is repeated over and over again to produce a cross-linked polymer or phenol-formaldehyde resin (e.g. Bakelite) in which the aromatic rings are linked to methylene bridges. 

Phenols can condense with aqueous formaldehyde in mildly alkaline solution with the introduction of a hydroxymethyl group in the ortho or para position to the phenolic hydroxyl group. In the presence of add, phenols react with formaldehyde to give the phenol-formaldehyde resins such as Bakelite. 

Chemical stability of carbon over the entire pH range has led to considerable interest in the development of carbon-based stationary phases for RPC. Porous graphitised carbon with sufficient hardness, well-defined and stable pore structure without micropores, which ensures sufficient retention and fast mass transfer can be prepared by a complex approach consisting of impregnation of the silica gel with a mixture of phenol and formaldehyde followed by formation of phenol-formaldehyde resin in the pores of the silica gel, then thermal carbonisation and dissolution of the silica gel by hydrofluoric acid or a hot potassium hydroxide. solution [48. The retention and selectivity behaviour of carbon phases significantly differs from that of chemically bonded pha.ses for RPC. Carbon adsorbents have greater affinity for aromatic and polar substances so that compounds can be separated that are too hydrophilic for adequate retention on a Cix column. Fixed adsorption sites make these materials more selective for the separation of geometric isomers [49]. 

The phenol/furfural resins have a greater hydrocarbon solvent tolerance than phenol/formaldehyde resins. This is an advantage in the preparation of resin solutions used for the impregnation of paper or cloth for laminating. 

A) Preparation of Phenol-Formaldehyde Resin. Place in an eight-inch tube 5 g of phenol, 15 ml of 40 per cent formaldehyde solution, and 3 ml of concentrated aqueous ammonia. Heat the tube for a few minutes with a small flame until the solution becomes opaque and milky. Cool the tube, and decant the upper layer, retaining the lower viscous material. Add 10-12 drops of acetic acid to the viscous material and heat in a water bath at 60 for thirty minutes. Pour some of the liquid into a glass tube 6 mm in diameter and 100-150 mm in length, sealed at one end. Place the remainder in a small clean test tube made of thin glass. Label both tubes, and place in oven at 80° until the next laboratory period. Break the tubes cautiously to obtain the clear transparent resin. 

The potential applications for conducting polymers are enormous and this has stimulated a large amount of research into this area. Not surprisingly, solid-state NMR spectroscopy has been applied to study these amorphous, insoluble and in many cases crosslinked materials [24]. Looking at the CP/MAS spectra of a series conducing polyacenic polymers, some of which were doped with iodine, it was possible to see the effect of the halogen upon conductivity. These resins were prepared by a conventional procedure for the preparation a Novolak-type phenol-formaldehyde resin. After synthesis, the phenol-formaldehyde resin were dissolved and solutions were cast as a film and heat treated to between 590-670°C in a N2 atmosphere to form the polyacenic film. The electrical conductivity of the films was shown to increase... 

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