Phenolic resins novolacs

There are two forms of phenolic resin, novolacs and resols. A novolac is a fusible resin incapable of hardening without the addition of a hardening agent. A resol is a resin which is capable of hardening under the influence of heat without the addition of any other product. 

Stopping the polymer at this point requires the ratio of formaldehyde to phenol to be less than unity. Both methylene and ether bridges are known to be present. The reaction is either acid or base catalyzed, and branching is uncommon at this stage. The products are variously known as A stage resins, novolacs, or resole prepolymers. 

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... 

Polyphenols. Another increa singly important example of the chemical stabilization process is the production of phenoHc foams (59—62) by cross-linking polyphenols (resoles and novolacs) (see Phenolic resins). The principal features of phenoHc foams are low flammabiUty, solvent resistance, and excellent dimensional stabiUty over a wide temperature range (59), so that they are good thermal iasulating materials. 

A hard carbon with high capacity can be made from epoxy novolac resin [12]. The epoxy resins used cost about US 2.50 per pound and give pyrolysis yields between 20 and 30%. However, it is well known that phenolic (or phenol-formaldehyde) resins can be pyrolyzed to give hard carbons with a yield of over 50% [42]. In addition, these resins cost about USSl.OO per pound. Phenolic resins therefore offer significant cost advantages over epoxy resins, so we... 

The formation of a phenolic resin is often formally separated into two steps, though it probably should be three. If we use a three-step model, the first step is activation of the phenol or aldehyde. The second step is methylolation, and the third is condensation or chain extension. In addition to the clarity provided by the formalism, these steps are also generally separated in practice to provide maximum control of exothermic behavior, with the strategy being to separate the exotherm from each step from that of the others as much as possible. As there are significant differences in the activation step and in the details of the methylolation and condensations steps of novolacs and resoles, we will treat the two types separately. 

Phenolics or phenol-aldehydes include the important commercial phenolic resin bakelite based on phenol and formaldehyde. A one-step process produces resol resin from more than one molecule of formaldehyde per phenol molecule. A two-step process uses an excess of phenol to produce novolacs - resins that have no reactive methylol groups and must be mixed with an aldehyde o undergo further reaction. 

An alternative copolymerization is illustrated by the method of Blasius. In this preparation, a phenol-formaldehyde (novolac) type system is formed. Monobenzo-18-crown-6, for example, is treated with a phenol (or alkylated aromatic like xylene) and formaldehyde in the presence of acid. As expected for this type of reaction, a highly crosslinked resin results. The method is illustrated in Eq. (6.23). It should also be noted that the additional aromatic can be left out and a crown-formaldehyde copolymer can be prepared in analogy to (6.22). ... 

For positive resists, mixtures of 1,2-naphthoquinone diazides with phenolic resins, mainly the polymer from 3-cresol and formaldehyde (Novolac), are used. 

Phenolic oligomers are prepared by reacting phenol or substituted phenols with formaldehyde or other aldehydes. Depending on the reaction conditions (e.g., pH) and the ratio of phenol to formaldehyde, two types of phenolic resins are obtained. Novolacs are derived from an excess of phenol under neutral to acidic conditions, while reactions under basic conditions using an excess of formaldehyde result in resoles. 

Phenolic resins were discovered by Baeyer in 1872 through acid-catalyzed reactions of phenols and acetaldehyde. Kleeberg found in 1891 that resinous products could also be formed by reacting phenol with formaldehyde. But it was Baekeland who was granted patents in 1909 describing both base-catalyzed resoles (known as Bakelite resins) and acid-catalyzed novolac products.2... 

This chapter emphasizes the recent mechanistic and kinetic findings on phenolic oligomer syntheses and network formation. The synthesis and characterization of both novolac- and resole-type phenolic resins and dieir resulting networks are described. Three types of networks, novolac-hexamethylenetetramine (HMTA),... 

Phenol-epoxy reaction. See also Epoxy-phenolic reaction entries tertiary amine-catalyzed, 412 triphenylphosphine-catalyzed, 412 Phenol-formaldehyde novolac resin, preparation of, 429... 

DSC and DMA scans of, 18 778 Novolac epoxy resins, 10 349 Novolac resins, 15 163. See also Novolacs in coatings, 18 782 in fiber bonding, 18 792 from phenolic resin polymerization,... 

Phenolic novolacs, 18 760-761 Phenolic resin adhesives, 18 783-784 Phenolic resin can coatings, 18 38 Phenolic resin composites, 18 792-794 Phenolic resin drying-oil varnishes, 18 783 Phenolic resin fibers, 18 797-798 mechanical properties of, 18 798 Phenolic resin foam, 18 795-796 Phenolic resin manufacturers, U.S., 18 774 Phenolic resin polymerization, 18 760-765 alkaline catalysts in, 18 762-765 neutral catalysts in, 18 761-762 strong-acid catalysts in, 18 760-761 Phenolic resin prepregs, 18 793 Phenolic resin production unit, 18 766 Phenolic resins, 10 409 18 754-755, 756-802 22 10 26 763 in abrasive materials, 18 786-787 in air and oil filters, 18 790 additional reactants in, 18 759 analytical methods for, 18 774-779 applications of, 18 781-798 batch processes for, 18 766 from biomass and biochemical processes, 18 769-770... 

Resinous adducts, 10 394 Resinous odor, 3 229t Resins. See also Epoxy resins Lacquer resins Novolac resins Phenolic resins Resole resins Thermoplastic resins acidic cation-exchange, 12 191 advanced materials, 1 693 antilipemic agents, 5 141 aromatic glycidyl amine, 10 372—373 chromatographic, 14 383-384 for coatings, 7 95-107 derived from furfuryl alcohol, 12 271— 272... 

While "conventional positive photoresists" are sensitive, high-resolution materials, they are essentially opaque to radiation below 300 nm. This has led researchers to examine alternate chemistry for deep-UV applications. Examples of deep-UV sensitive dissolution inhibitors include aliphatic diazoketones (61-64) and nitrobenzyl esters (65). Certain onium salts have also recently been shown to be effective inhibitors for phenolic resins (66). A novel e-beam sensitive dissolution inhibition resist was designed by Bowden, et al a (67) based on the use of a novolac resin with a poly(olefin sulfone) dissolution inhibitor. The aqueous, base-soluble novolac is rendered less soluble via addition of -10 wt % poly(2-methyl pentene-1 sulfone)(PMPS). Irradiation causes main chain scission of PMPS followed by depolymerization to volatile monomers (68). The dissolution inhibitor is thus effectively "vaporized", restoring solubility in aqueous base to the irradiated portions of the resist. Alternate resist systems based on this chemistry have also been reported (69,70). 

Can you explain why there are so many terms, such as novolac, resole, etc., used in phenolic resin technology ... 

From this result on MRS, we expected that a combination of phenolic-resin-based resist and aqueous alkaline developer would lead to etching-type dissolution and non-swelling resist patterns. In this paper, we report on a new non-swelling negative electron beam resist consisting of an epoxy novolac, azide compound and phenolic resin matrix (EAP) and discuss the radiation chemistry of this resist. 

Materials. Epoxy novolac, DEN-431, obtained from Dow Chemical Co. was selected as the epoxy component. A 3,3 -diazidodiphenyl sulfone synthesized in our laboratory (5) was used as the azide compound. Poly(/7-vinyl phenol) obtained from Maruzen Oil Co. was used as the phenolic resin matrix. The coating solvent was cyclohexanone. The developer used in this study was 0.1 N tetramethylammonium hydroxide aqueous solution. 

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