Novolac resins preparation

Linear novolac resins prepared by reacting para-alkylphenols with paraformaldehyde are of interest for adhesive tackifiers. As expected for step-growth polymerization, the molecular weights and viscosities of such oligomers prepared in one exemplary study increased as the ratio of formaldehyde to para-nonylphenol was increased from 0.32 to 1.00.21 As is usually the case, however, these reactions were not carried out to full conversion, and the measured Mn of an oligomer prepared with an equimolar phenol-to-formaldehyde ratio was 1400 g/mol. Plots of apparent shear viscosity versus shear rate of these p-nonylphenol novolac resins showed non-Newtonian rheological behavior. 

Mandal and Hay28 used MALDI-TOF mass spectrometry to determine the absolute molecular masses and endgroups of 4-phenylphenol novolac resins prepared in xylene or chlorobenzene. Peaks with a mass difference of 44 (the molecular weight of a xylene endgroup) suggested that reactions conducted in xylene included some incorporation of xylene onto the chain ends when a strong acid such as sulfuric acid was used to catalyze the reaction. By contrast, no xylene was reacted into the chain when a milder acid catalyst such as oxalic acid was used. No chlorobenzene was incorporated regardless of the catalyst used. 

The most common crosslinking agent for novolac resins is HMTA which provides a source of formaldehyde. Novolac resins prepared from a phenol-formaldehyde (F/P) ratio of 1/0.8 can be cured with 8-15 wt % HMTA, although it has been reported that 9-10 wt % results in networks with the best overall performance.3... 

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

C-NMR spectroscopy was used extensively to investigate the chemical structures of phenolic resins (11,15-18) and related model compounds (17-19). These studies provided useful information on the complex chemical structure of PF resins. C-NMR spectroscopy was also used to study the chemical structure and to determine the copolymer composition of novolac resins prepared from 2-methylphenol, 3-methylphenol or 4-methylphenol (20,21) or from mixtures of... 

High orthonovolac resins have been reported to be prepared by reacting phenol and formaldehyde in the presence of a divalent electropositive metal oxide, hydroxide, or organic salt based on sulfonates, fluoroborates, or acids selected from sulfonic or fluoroboric acid or mixtures [43]. This is in contrast to the conventional novolac resins prepared with strong acids (sulfuric acid, hydrochloric acid, or oxalic acid) and have a preponderance of para/para and ortho/para methylene bridges. The high ortho novolacs have mostly ortho/ortho methylene bridges such as ... 

Void-free phenolic-epoxy networks prepared from an excess of phenolic novolac resins and various diepoxides have been investigated by Tyberg et al. (Fig. 7.37).93 -95 The novolacs and diepoxides were cured at approximately 200°C in the presence of triphenylphosphine and other phosphine derivatives. Network densities were controlled by stoichiometric offsets between phenol and... 

SPP was prepared by dissolving a novolac resin dlazonaph-thoqulnone sulfonyl ester (DNQ) and APSQ In methyl Isobutyl ketone. A concentration of 20 wt% DNQ relative to APSQ Is sufficient for It to act as a dissolution Inhibitor. 

Epoxy novolac resins are polyglycidyl ethers of a novolac resin. They are prepared by reacting epichlorohydrin with a novolac resin (see Chap. 2). The most common epoxy novolacs are based on medium-MW molecules with phenol and o-cresol novolacs. They generally have significantly different properties from DGEB A epoxies because of the presence of the phenolic structure. 

PVC = polyvinyl chloride, PVDF = polyvinylidene fluoride, PPS = polyphenylene sulfide, ENR = epoxy novolac resin. d The lower the preparation temperatures, the higher the reversible and irreversible capacities (within the limits specified in the table). e The reversible capacity depends on the cycle number, cutoff voltage, and other experimental parameters. Maximal reversible capacity around 650 mAh/gr could be obtained. 

A novolac-type of resin has been prepared from the condensation product of an-isole with formaldehyde. Anisole has been condensed with an equimolecular amount of formaldehyde in the presence of sulfuric add and the product sulfonated at g 120 "C with sulfuric add. The sulfonated product has been made insoluble by treatment with formaldehyde or by heating at 140°-145 °C, and the resin prepared in this way has a superior resistance to the action of oxidizing agents such as IN nitric acid and O.IN potassium permanganate. 

Trimethylsilylmethylphenol and o-cresol were obtained from Petrarch Systems, Inc. and Aldrich Chem. Co. Inc., respectively. Silylated novolac (Sl-novolac) resins were prepared by condensation polymerization of p-trimethylsilylmethyl phenol, o-cresol and formaldehyde. Poly(2-methyl-l-pentene-sulfone) (PMPS) was prepared as described in the literature (12). 

Table 59 Preparation Conditions and Properties of Novolac Resin (15)...

Novolac resins are generally prepared by the acid-catalysed reaction of phenol and aqueous formaldehyde under reflux. Although strong acids such as sulphuric and hydrochloric acid can be used, the weaker oxalic and phosphoric acids give a less exothermic and more... 

The novolac resin used in NPR formulations was a proprietary resin manufactured by Polychrome Corp. to Bell Laboratories specifications. Samples of NPR containing 20% and 50% PMPS were prepared in Hunt Photoresist Thinner (mixture of ethoxyethyl acetate, butyl acetate and xylene), filtered through 1 /un Teflon filters and spin coated onto undoped silicon wafers to give films 9,000 A thick. All films were prebaked at 110 C for 2 hr. Film thickness was measured directly by a Nanometrics Nanospec AFT microarea thickness gauge. Alternatively, the samples were coated with a thin layer of aluminum and measured mechanically with a Dektak. 

A cresol novolac resin has been synthesized which exhibits a much greater dissolution-inhibiting effect than in various commercially available novolac or phenolic resins. Using this resin, a positive electron beam resist was prepared and its exposure characteristics were examined. A tetramethylammonium hydroxide aqueous solution was used as the developer. The sensitivity reaches 3xl0 6 C/cm2 without post-exposure baking. It was found that the sensitivity to double exposure was much higher than that to single exposure with the same total dose. A similar phenomenon was also... 

Novolac Preparation Novolac resins were prepared by an acid catalyzed condensation of m- and p-cresols with formaldehyde. A three necked flask with a distillation reflux condenser, thermometer and mechanical stirrer was charged with m- and p-cresols, formaldehyde aqueous solution, and cone, hydrochloric acid as a catalyst. The flask was immersed in an oil bath and heated to 90 C and kept for 2 hours while undergoing stirring. After the flask was cooled to room temperature on standing, the supernatant layer of the contents was removed by decantation. Then the volatile components were eliminated by distillation under a nitrogen gas flow and slow heating to 175°C. The molten content was poured into a stainless steel tray to cool. 

Resist Preparation Resist solutions were prepared by dissolving novolac resins and PMPS in isoamyl acetate. The solutions were then filtered through an 0.2 um Teflon filter. 

The novolac resins are prepared by using acidic catalysts and a deficiency of formaldehyde. Because this type of resin is less reactive, cross-linking is accomplished by the addition of a curing agent or catalyst. The most common is hexamethylenetetramine or "hexa." The curing agent serves as a latent source of formaldehyde. As in the case of the resoles, volatiles are emitted during the cure. The chemistry of the phenolic resin is old but complex and well documented in the literature (10). 

Novolacs are linear polymers. Metacresol, a very reactive derivative of phenol, is typically used to prepare novolac resins. The presence of a methyl group at the meta (3 or 5) position of the henzene ring of phenol enhances the reactivity of the compound toward polymerization with formaldehyde. Novolac resins made with metacresol are also more moisture resistant than those with phenol. After preparation, novolac s ability to resist further polymerization is attributed to the fact that the chains terminate with phenol groupings, having been prepared with an excess of phenol. ... 

Attempts have been made over time to improve the physical properties of novolacs. The use of phenol formaldehyde resins prepared in alkaline medium in photoresist compositions is mentioned in a Kalle Co. AG patent. The use of polyvinyl ethers in combination with novolacs to impart stickiness and plasticization action to the latter was patented by Christensen. Steinhoff, Isaacson, and Roelants of the Shipley Company mention the use of vinyl ethers in a patent on roller coating. Lower alkyl polyvinyl ethers, such as methyl, ethyl, butyl, and isobutyl, are added to novolac resins to improve coating flexibility and adhesion to metal surfaces as well as to improve resistance to mildly alkaline solutions. The use of styrene, methyl styrene, and styrene-maleic anhydride copolymers in combination with novolac was mentioned in several patents of both Shipley and Kalle Co. AG. When novolac is copolymerized with maleic anhydride, a resin that is readily soluble in alkaline solutions is obtained. ... 

Novolac resins are normally prepared by the reaction of a molar excess of phenol with formaldehyde (commonly about 1.25 1) under acidic conditions. The reaction is commonly carried out batchwise in a resin kettle of the type used for resol manufacture. Typically, a mixtme of phenol, formalin, and acid is heated under reflux at about 100°C. The acid is usually either hydrochloric acid (0.1-0.3% on the weight of phenol) or oxalic acid (0.5-2%). 

Choi and Chung [16] were the first to prepare phenolic resin/layered sihcate nanocomposites with intercalated or exfoliated nanostructures by melt interaction using linear novolac and examined their mechanical properties and thermal stability. Lee and Giannelis [10] reported a melt interaction method for phenolic resin/clay nanocomposites, too. Although PF resin is a widely used polymer, there are not many research reports on PF resin/montmorillonite nanocomposites, and most of the research investigations have concentrated on linear novolac resins. Up to now, only limited research studies on resole-type phenolic resin/layered silicate nanocomposites have been published [17-19] and there is still no report on the influence of nano-montmorillonite on phenolic resin as wood adhesive. Normally H-montmorillonite (HMMT) has been used as an acid catalyst for the preparation of novolac/layered silicate nanocomposites. Resole resins can be prepared by condensation reaction catalyzed by alkaline NaMMT, just as what HMMT has done for novolac resins. 

The Phenolic Resins Modified with Titanium are Synthesized from a High Ortho Novolac Resin and Tetraisopropyl Titanate. The Phenolic Resin Modified with both Titanium and Silicon is Prepared from 2 Weight Percent Titanium Containing Phenolic Resin and Diphenylsilanediol. (Data from Ref.[l 80])... 

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