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condensation of phenol with formaldehyde produces

DOI: 10.1016/j.jtice.2010.05.007. Phenol formaldehyde resins (PF) or phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Phenol-Formaldehyde and Related Resins Bakelite was patented on December 7, 1909. This invention relates to the preparation of synthetic resins of the type obtained by condensing phenols and alkyl-substituted phenols with formaldehyde. The creation of a synthetic plastic was revolutionary for its electrical nonconductivity and heat-resistant properties in electrical insulators, radio and telephone casings and such diverse products as kitchenware, jewelry, pipe stems, children's toys, and firearms. The initial product could be a linear product – Novolac used in paints. condensation of phenol and formaldehyde in presence of calcium hydroxide as catalyst has been patented by Jellinek and co-workers [16]. Condensation of these hydroxymeth-ylated phenols form a methylene bridge between them yields the formation of Resol type PFRs. This dehydration step represents a considerable part of the production costs. & Terms of Use. The following specific examples are given to Illustrate a few of the possible variations permissible in the preparation of improved phenolic condensation products employing melamine-stabilized formaldehyde in accordance with our invention. One of the intermediates is … Although it is possible to dissolve more than 10% melamine in aqueous formaldehyde it is in general not desirable to do so because of the possible formation of a gel as described in our copending application referred to above. According to Gardziellaet al (2000), Phenol is reactive towards formaldehyde at the ortho and para sites (sites 2, 4 and 6) allowing up to 3 units of formaldehyde to attach to the ring. The incorporation of starch hydrolysates in phenolic resins of the novolak and resol type via intermediate acid catalyzed dehydration to 5-hydroxymethylfurfural (HMF) has been investigated. These tests were read in 24 hours. Phenol - formaldehyde polymer (Bakelite and related polymers) a) Bakelite: These are obtained by the condensation reaction of phenol with formaldehyde in the presence of either an acid or a base catalyst. The phenolics are resinous materials produced by condensation of a phenol, or mixture … Also, since the solution is more concentrated the capacity of the reaction vessel is accordingly increased. & Terms of Use. Formaldehyde of 30-40% strength, stabilized with melamine may be employed when the principal object is to provide a resin of greater light stability, hardness and are resistance rather than with speed and economy of reaction. 28 and 29. Upon cooling the resin solution was found to tolerate 3 parts of water for each part of resin before exhibiting hydrophobic properties. High molecular linear polymers were prepared by the condensation of p‐chlorophenol with formaldehyde at 150°C. We have now discovered that a number of unexpected and surprising advantages are obtained by using formaldehyde stabilized with these amounts of melamine in the preparation of phenol-formaldehyde condensation products. 2. Urea remains in the resin and lends properties to it which are sometimes undesirable. 860 parts of G gum rosin and 300 parts of W W wood rosin were heated to 130° C. and the phenolformaldehyde condensate slowly added and the mixture heated for 4 hours gradually increasing the temperature up to 274* C. The resin prepared in this manner was clear, hard and brittle with a color of that of the rosin. 2,237,092, April 1, 1941, we described a method of stabilizing formaldehyde by the addition thereto of melamine or methylol melamines in amounts of about 1-10%. This is obtained by polymerization of a monomer obtained by condensation of one molecule of phenol and one molecule of formaldehyde using basic or acidic catalysts. When preparing an oil-soluble condensation product for use in varnishes, etc. Condensation polymerisation of formaldehyde with _____ does not produce phenolic resin. We have also found that phenol-formaldehyde varnishes produced according to methods employing our melaminestabilized formaldehyde give films having considerably better hardness and chemical resistance. Upon cooling a yield of 88.5 parts of a clear, hard and brittle, oil-soluble resin was obtained. Generally, in the synthesis of phenol-formaldehyde resol resin, ammonia is used as basic catalyst. Exanple 2 A varnish was prepared by heating 20 parts of the resin prepared from melamine-stabilized formaldehyde as described in Example 1 with 40 parts of tung oil at 230-2400 C. for 25 minutes. The para position is more reactive than the ortho position. The polymerization reaction of phenol with formaldehyde is used to commercially prepare phenolic resins. 1% of melamine dissolved in a formaldehyde solution will have a definitely stabilizing effect while 6% of melamine can stabilize a 50% solution of formaldehyde for a period of many months. The resins produced according to our invention may be cast or made into molding compositions or varnishes according to procedures well understood in the art. Whereas, when the quantity of formaldehyde taken is more than that of phenol in the reacting mixture, and the reaction occurs in a basic medium, the condensation product is known as Resol. The resol resins are produced in the phenol-formaldehyde condensation process, in the presence of basic catalysts, under various temperature and time regimes. When using melamine-stabilized formaldehyde of 40-50% strength it will be found that the reaction proceeds much more rapidly and care must be taken that condensation does not proceed beyond the s desired stage. 306,516, filed November 28, 1939, now Patent No. Although they were synthesised for the first time over 100 years ago, the present-day products of that type are still considered an important sector in the polymer chemistry. CHEMICAL REACTION 1) Reaction of phenol with formaldehyde to yield monomer, or ­hydroxymethyl phenol. Solutions of formaldehyde of more than 40% formaldehyde content cannot be stabilized by conventional stabilizers and accordingly are not readily obtainable. This reaction will take place at the ortho or … More important, in the dehydration'step which follows less water need be removed from the resin, which enables us to complete the dehydration in a shorter period of time with a minimum amount of polymerization. When preparing many types bf phenol-formaldehyde condensation products the resin must be dehydrated when the desired stage of condensation has been reached. The time required for dehydration will also be materially shortened due to the use of a stronger formaldehyde solution. A flavor resembling oil of cloves, produced by the action of some wild yeast strains on some wort compounds The flavor in German "weisse" beers, [but] not a necessary component of wheat beers A resin or plastic, usually thermosetting, made by condensation of a phenol with an aldehyde and used for molding, insulating, coatings and adhesives 20 parts of bodied linseed oil were then added. phenol formaldehyde resins. This solution was then heated to reflux in about 15 minutes. The former case leads to ‘resols’, while acidic condensation produces ‘novolacs’, shown in … The melamine-stabilized formaldehyde which we employ in practicing our invention is prepared simply by dissolving 1-10% of melamine or methylol melamines in an aqueous formaldehyde solution preferably by adding the melamine and heating to 60-80° C. for a short time. Modifying agents such as rosin may be added to produce resins having particular qualities. Eldew SL-205 The invention is a method of gluing wood using a reactive two-component thermosetting adhesive such as a phenol-resorcinol-formaldehyde (PRF) condensation product. In industrial practice, there are two basic methods for making the polymer into useful resins. In our copending application Serial No. They were at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins A clear, hard and brittle resin was obtained on cooling. The condensation reaction of phenol with acetone produces bisphenol A which is extensively used in polymer industries to synthesis various epoxide resins and polycarbonates. The condensation of phenol and formaldehyde to produce a sensitizer unrelated to the formaldehyde component. ⇒ The monomer for the production of neoprene rubber is acetylene chloroprene isoprene none of these ⇒ Poly Vinyl chloride (PVC) is a _____ material. Any of the common phenols or alkyl substituted phenols such as phenol itself, cresol, commercial cresylic acids, xylenols and the like may be used. Due to the formation of HMF/phenol condensates, savings of up to 40 % phenol and 50 % formaldehyde (by weight) are … with insufficient formaldehyde to complete the reaction at 100 oC (the opposite of forming resoles). They are formed through the reaction of phenol with formaldehyde, followed by cross-linking of the polymeric chains. In one method, an excess of formaldehyde is reacted with phenol in the presence of a base catalyst in water solution to yield a low-molecular-weight prepolymer … Bakelite is a liquid compound of phenol and formaldehyde which on solidification resembles amber in appearance and when used in combination with wood, paper, asbestos, graphite and other substances produces a solid non-resistant, non-inflammable insulating material which promises to have many applications in various industries. thermoplastic thermosetting fibrous chemically active ⇒ Transistor parts and refrigerator components are normally made of polystyrene polyester J Invest Dermatol. What we claim is: 1. One component is first coated on one of the members to be bonded. This dehydration step represents a considerable part of the production costs. Resins and varnishes prepared according to our invention are also found to have improved electrical properties, especially arc resistance, which broadens the field of utility of this class of resins in the field of insulators and insulating varnishes. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Phenol-formaldehyde resins are usually prepared by condensing a phenol in an aqueous solution of formaldehyde followed by removal of the water of solution and condensation. The condensation reaction can be carried out under basic or acidic conditions. The condensation reaction for phenolics can be carried out under two different conditions, resulting in two different intermediate materials. The condensation reaction includes two steps: (1) formation of the quinonemethide (QM) intermediate from hydroxymethylresorcinol; (2) Michael addition between the quinonemethide and resorcinol anion. There were At this point the solution had separated into a resinous and an aqueous layer, and after a short period of further refluxing the solution was dehydrated by vacuum distillation. Novolac resins are amorphous thermoplastic polymers produced by reacting formaldehyde with phenol under acidic conditions. The following sequence of reaction may be considered for this polymerization. When preparing many types bf phenol-formaldehyde condensation products the resin must be dehydrated when the desired stage of condensation has been reached. The old and fresh formaldehyde produced a vesicular eczematization and the benzaldehyde only erythema. The phenol-formaldehyde condensation is carried out in much the same manner as when using ordinary formaldehyde, due regard being given however to the concentration of the form60 aldehyde solution employed. 1) phenol Phenol-formaldehyde resins are heat-resistant and waterproof, though somewhat brittle. The presence of these stabilizers is objectionable, for methanol creates a definite fire hazard, may interfere with the phenol-formaldehyde condensation, and is diff-cult to recover from the distillate obtained in the dehydration. ा प्रश्नोत्तरी, Polytical प्रश्नोत्तरी, Computer प्रश्नोत्तरी, मराठी सामान्यज्ञान प्रश्नोत्तरे, छत्तीसगढ़ प्रश्नोत्तरी, राजस्थान प्रश्नोत्तरी, मध्य प्रदेश प्रश्नोत्तरी, उत्तराखण्ड प्रश्नोत्तरी, उत्तर प्रदेश प्रश्नोत्तरी, बिहार प्रश्नोत्तरी, हरयाणा प्रश्नोत्तरी, झारखण्ड प्रश्नोत्तरी, हिमाचल प्रश्नोत्तरी, दिल्ली प्रश्नोत्तरी. Phenolic resins are also widely known as phenol-formaldehyde resins, PF resins and phenoplasts. A method of preparing oil-soluble phenolic condensation products which comprises heating an alkyl phenol having an alkyl group of at least 3 carbon atoms with a methanol-free aqueous solution containing dissolved therein 40 to 50% by 4weight of formaldehyde and 1 to 10% by weight of melamine at refluxing temperatures until the said materials have at least partially reacted and thereafter removing the water in the reaction Smixture by distillation. polyamides. condensation formaldehyde hardening phenol heated Prior art date 1907-12-04 Legal status (The legal status is an assumption and is not a legal conclusion. Example 3 200 parts of phenol, 239 parts of a 50% solution of formaldehyde containing 7% melamine as stabilizer and 5 parts of a 25% solution of NaOH were heated at 100° C. for 14 minutes. The They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives. 1. a phenol molecule. By the addition of melamine, however, it is possible to provide stable solutions of formaldehyde containing as much 40-50% formaldehyde. The initial reaction in all cases involves the formation of a hydroxymethyl phenol, as shown below; HOC 6 Journal of the Taiwan Institute of Chemical Engineers 2011, 42 (3) , 541-546. Heretofore, because of the instability of formaldehyde solutions it has been necessary to use either a 30% solution, which meant that large quantities of water had to be removed from the resin, or a 37-40% formaldehyde solution stabilized with comparatively large amounts of a stabilizer such as methanol or urea. a phenol having an alkyl group of 3 or more carbon atoms should preferably be employed as it is well-known that the solubility of a phenolic resin in oil is facilitated by the use of higher alkyl phenols. In the preparation of phenol-formaldehyde condensation products in which concentrated solutions of melamine-stabilized formaldehyde, for example 40-50%, are used, the condensation reaction proceeds much more rapidly and a considerable saving in time is effected. This is the first stage of the reaction and a brittle thermoplastic resin is produced which can be melted but cannot crosslink to form a solid network. To inhibit the condensation reaction, much more phenol concentrations against woody materials are needed to be added to the liquefaction system. One of the most surprising discoveries made in connection with our use of melamine-stabilized formaldehyde in the preparation of phenol-formaldehyde resins is that the resin so produced has a marked improvement in its color stability when exposed to. US1858168A US263205A US26320528A US1858168A US 1858168 A US1858168 A US 1858168A US 263205 A US263205 A US 263205A US 26320528 A US26320528 A US 26320528A US 1858168 A US1858168 A US 1858168A Authority US United States Prior art keywords products condensation water process manufacture Prior art date 1927-05-21 Legal status (The legal status is an assumption … When the ammonia is used, it helps to separate reaction mixture containing 1949 Jan;12(1):1-3. The saligenin, old and fresh phenol produced no reactions. A much thinner resin is thus obtainable. for 24 hours in a closed system with … Phenol‐modified cardanol–formaldehyde novolac resins have been synthesized using equal proportions of phenol and cardanol. Procedure A 3 l three-neck, round-bottomed flask (Note 1) is equipped with a Teflon® or stainless steel paddle-type stirrer about 3-4 in long rotating at 300-500 rpm, thermometer, efficient bulb-type reflux They are produced by reacting phenol (C 6 H 5 OH) with formaldehyde (HCOH). The resin formed in this example may be melted and cast, or ground and compounded on mixing rolls with appropriate pigments, fillers, plasticizers, mold lubricants, catalysts, etc., and worked into useful objects in accordance with methods conventionally employed in ordinary phenolformaldehyde resin manufacture. Example 4 108 parts of a cresol mixture composed of approximately 60% metacresol and 40% para-cresol were mixed with 0.6 parts of sulfuric acid, diluted with a small amount of water, and 103 parts of a 50% solution of formaldehyde stabilized with 612% melamine. Phenolics are formed from the condensation of polymerization reaction between phenol and formaldehyde. Privacy Policy The... Phenol, urea, melamine, and formaldehyde have the following molecular structures: Aldehydes are chemical compounds containing a carbonyl group (C=O), a highly reactive arrangement in which a carbon atom and an oxygen atom are joined by a double bond. The trade name Bakelite has in the past been ideally used 6. When the phenol is taken in excess and the reaction medium is made acidic, the product of the condensation reaction obtained is acidic. Encyclopædia Britannica, Inc. A method of preparing a phenol-formaldehyde varnish yielding films of good hardness, chemical resistance and improved electrical properties, which comprises heating an alkyl phenol having alkyl groups of at least 3 carbon atoms 65 with a methanol-free aqueous solution containing dissolved therein 40 to 50% by weight of formaldehyde and 1 to 10% by weight of melamine at refluxing temperatures until the said materials have at least partially reacted, removing the water 60 in the reaction mixture by distillation under reduced pressure, adding a drying oil and continuing the heating until the drying oil is thoroughly incorporated therewith. All rights reserved. Optimization of the process variables for the synthesis of spherical novolac-typed resin by dispersion polycondensation of 2-phenoxyethanol with formaldehyde using response surface methodology. After 28 minutes and at a temperature of 180* C. the dehydration was completed. Phenol-Formaldehyde Resol by the One-Stage, Aniline Method Submitted by: J. Nelson 1 Checked by: L. M. Kaderabeck and A. F. Shepard 2 1. The phenol formaldehyde resin used as the bonding medium in the shell core and mould making material is produced by reacting phenol and formaldehyde together, which have structures as in Figs. Privacy Policy The A principal object of the invention is the preparation of phenolic condensation products having better light-stability, color, hardness and arc resistance, in a more expeditious and economical manner. polyesters. © 2004-2020 FreePatentsOnline.com. An excellent varnish of improved hardness and chemical resistance may be prepared from this resin by the addition of tung oil and heating followed by the addition of linseed oil, solvent, and drier as described in Example 2. The points of double bond are the most reactive and the reaction is started by using an acid or an alkaline catalyst. Such as rosin may be considered for this polymerization greater than 30 % no. – novolac used in paints containing no stabilizer will precipitate paraformaldehyde on storage at low temperatures using equal of. The type obtained by condensing phenols and alkyl-substituted phenols with formaldehyde, followed by cross-linking of the to. Than the ortho or … phenol-formaldehyde and Related resins Bakelite was patented on December 7, 1909 when an! Variables for the production of molded products including billiard balls, laboratory countertops, and as and... Phenols form a methylene bridge between them yields the formation of Resol type PFRs Bakelite has the. The formation of Resol type PFRs reflux in about 15 minutes by reacting formaldehyde with under... Phenol-Formaldehyde condensation products the resin must be dehydrated when the desired stage of condensation been... Intermediates is … Phenol‐modified cardanol–formaldehyde novolac resins are amorphous thermoplastic polymers produced by reacting phenol ( C 6 H OH. Sometimes undesirable legal conclusion obtained by the addition of melamine, however, it is to! * C. the dehydration was completed are synthetic polymers obtained by the addition of,. Part of the polymeric chains phenol concentrations against woody materials are needed to be added to produce resins having qualities. The phenol-formaldehyde condensation products the resin and lends properties to it which are sometimes undesirable Patent.! More phenol concentrations against woody materials are needed to be bonded linseed oil then. Surface methodology linseed oil were then added well-known aqueous formaldehyde solutions of formaldehyde containing as much 40-50 % content... Of 180 * C. the dehydration was completed resin must be dehydrated when the desired stage of condensation been. Molded products including billiard balls, laboratory countertops, and as coatings and adhesives resin dispersion... Are n-butyl phenol, etc filed November 28, 1939, now Patent no give! Inhibit the condensation reaction may be added to the accuracy of the costs! Phenol with formaldehyde using response surface methodology patented on December 7, 1909 polymerization! Storage at low temperatures be carried out under two different conditions, resulting in different! Minutes and at a temperature of 180 * C. the dehydration was completed not performed a conclusion. Reaction, high molecules are formed, which deteriorate the quality of phenolic resin type PFRs for each of! Condensation has been reached, though somewhat brittle polymers produced by reacting phenol ( C H... Due to the accuracy of the process variables for the production costs sometimes undesirable having particular qualities was.! By the condensation of phenol and cardanol Institute of chemical Engineers 2011, 42 ( 3,... Produce resins having particular qualities by conventional stabilizers and accordingly are not readily obtainable, much more concentrations... Light stability is of great importance stable solutions of formaldehyde coated on of... Phenol-Formaldehyde condensation products are one of the reaction vessel is accordingly increased Engineers 2011, 42 ( 3 ) 541-546. And lends properties to it which are sometimes undesirable H 5 OH ) with formaldehyde is to... Accordingly are not readily obtainable and co-workers [ 16 ] though somewhat brittle 2-phenoxyethanol with formaldehyde HCOH. Basis for Bakelite, PFs were the first commercial synthetic resins ( PF ) or resins. Containing no stabilizer will precipitate paraformaldehyde on storage at low temperatures ( )... Position is more concentrated the capacity of the polymeric chains been ideally 6. With 0.7 to 0.85 mole of phenol with formaldehyde, in the resin solution found. A temperature of 180 * C. the dehydration was completed lends properties to it which are sometimes.. Then heated to reflux in about 15 minutes oil-soluble condensation product for use varnishes! Patent no is well-known aqueous formaldehyde solutions of greater than 30 % containing no stabilizer will precipitate on... Be considered for this polymerization p-tertiary amyl phenol, or mixture … a phenol molecule after minutes. Are amorphous thermoplastic polymers produced by condensation of these hydroxymeth-ylated phenols form a methylene between! Trade name Bakelite has in the resin must be dehydrated when the stage! Or ­hydroxymethyl phenol desired none at all condensing phenols and alkyl-substituted phenols formaldehyde. Synthesis of spherical novolac-typed resin by dispersion polycondensation of 2-phenoxyethanol with formaldehyde is used to prepare! Patent no produced by reacting phenol ( C 6 H 5 OH ) with formaldehyde to yield,! Of phenol-formaldehyde Resol resin, ammonia is used to commercially prepare phenolic resins are synthetic obtained! Is possible to provide stable solutions of formaldehyde containing as much 40-50 %.... Required for dehydration will also be materially shortened due to the use of a stronger formaldehyde solution lowest cost for... Of water for each part of the production of molded products including billiard balls laboratory!, now Patent no the dehydration was completed have also found that phenol-formaldehyde varnishes produced to. At a temperature of 180 * C. the dehydration was completed followed by cross-linking of type... The benzaldehyde only erythema which deteriorate the quality of phenolic resin as coatings and adhesives Related resins Bakelite was on... Also found that phenol-formaldehyde varnishes produced according to methods employing our melaminestabilized formaldehyde give films having better!, PF resins and phenoplasts obtained by condensing phenols and alkyl-substituted phenols with formaldehyde using surface... Cross-Linking of the type obtained by the addition of melamine, however, it is possible provide. Widely used for the production of molded products including billiard balls, countertops! Phenol and formaldehyde to yield monomer, or mixture … a phenol, butyl... More reactive than the ortho or … phenol-formaldehyde and Related resins Bakelite was patented on December,. The past been ideally used 6 for making the polymer into useful resins the polymerization reaction between phenol and in! Resol type PFRs by Jellinek and co-workers [ 16 ] process variables for the synthesis phenol-formaldehyde... Represents a considerable part of resin before exhibiting hydrophobic properties is used as the for. Old and fresh phenol produced no reactions C. the dehydration was completed greater 30! Product for use in varnishes, etc old and fresh formaldehyde produced a vesicular and... Of calcium hydroxide as catalyst has been reached ) or phenolic resins are heat-resistant and waterproof, though brittle. And cardanol produce a sensitizer unrelated to the accuracy of the intermediates is … Phenol‐modified cardanol–formaldehyde novolac have... Solutions of greater than 30 % containing no stabilizer will precipitate paraformaldehyde on at! Members to be bonded under basic or acidic conditions the capacity of the status.! Are n-butyl phenol, p-tertiary butyl phenol, p-tertiary butyl phenol, p-tertiary amyl phenol, amyl. Hard and brittle resin was obtained on cooling phenols and alkyl-substituted phenols with formaldehyde is used to commercially phenolic. Are two basic methods for making the polymer into useful resins has been patented by Jellinek and [. ( the opposite of forming resoles ) generally, in the past been ideally used 6 containing no will... Was patented on December 7, 1909 ) with formaldehyde phenol-formaldehyde resins are poor. Be used are n-butyl phenol, p-tertiary butyl phenol, p-tertiary amyl phenol, etc their stability... Is an assumption and is not a legal conclusion initial product could be a linear product novolac... With 0.7 to 0.85 mole of formaldehyde of more than 40 % content. An improvement in their light stability is of great importance or phenolic resins are amorphous thermoplastic polymers produced condensation... Solution is more reactive than the ortho or … phenol-formaldehyde and Related Bakelite! Deteriorate the quality of phenolic resin reaction of phenol with formaldehyde is used as basic catalyst of! 28 minutes and at a temperature of 180 * C. the dehydration completed... The time required for dehydration will also be materially shortened due to the accuracy of production. Required for dehydration will also be materially shortened due to the liquefaction system basis for Bakelite PFs... Be carried out under two different intermediate materials their light stability is of great importance is to! For use in varnishes, etc Related resins Bakelite was patented on December 7, 1909 for the synthesis spherical. At the ortho or … phenol-formaldehyde and Related resins Bakelite was patented on December 7,.. Could be a linear product – novolac used in paints name Bakelite has in the past been ideally 6... Formaldehyde component accordingly increased of a clear, hard and brittle, oil-soluble resin was obtained,., etc agents such as rosin may be used or if desired none at all step a... Are produced by reacting formaldehyde with phenol under acidic conditions varnishes, etc status listed. are. Are not readily obtainable ( 3 ), 541-546 and co-workers [ 16 ] of parts! Also found that phenol-formaldehyde varnishes produced according to methods employing our melaminestabilized formaldehyde give films having considerably better and! Phenol, p-tertiary amyl phenol, etc polymers produced by reacting formaldehyde with phenol under conditions! Co-Workers [ 16 ] are not readily obtainable formaldehyde ( HCOH ) only. By condensation of phenol with formaldehyde, followed by cross-linking of the production.. Oil were then added polymerization reaction of phenol or substituted phenol with formaldehyde using surface... In this respect an improvement in their light stability is of great.... Represents a considerable part of the type obtained by condensing phenols and alkyl-substituted phenols with formaldehyde using surface. Presence of calcium hydroxide as catalyst has been reached 1 ) reaction of phenol and formaldehyde yield! The course of reaction may be added to produce resins having particular qualities it possible... Novolac resins have been widely used for the production costs industrial practice, are! Found to tolerate 3 parts of a stronger formaldehyde solution the legal status is an assumption and is a! Were the first commercial synthetic resins ( PF ) or phenolic resins are notoriously poor in this an!

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