CA1059673A - Aqueous phenolic resole dispersion containing gum ghatti interfacial agent - Google Patents

Abstract

AQUEOUS PHENOLIC RESOLE DISPERSION CONTAINING
GUM GHATTI INTERFACIAL AGENT

ABSTRACT OF THE DISCLOSURE

Aqueous phenolic resole dispersions are disclosed. The dispersions are produced in the presence of gum ghatti and a thickening agent. The dispersions of the invention contain phenolic resole particles that can be very small and uniform in size, thereby enhancing the utility of said dispersions in such end use appli-cations as coatings and adhesives.

1.

Description

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~ ~ S~ ~7 3 The invention relates to aqueous phenolic resole dispersions containing gum ghatti and a thickening agent.
In U.S. Patent No. 3,823,103, there is disclosed aqueous phenolic resole dispersions that are produced in the presence of gum arabic and at least one other gum.
These dispersions are characteriz~ed by excellent stability and the ability to be infinitely diluted with water. In a preferred aspect, they can have particles whose average diameters are between about 5 to 20 microns, with substan-tially all the resin particles having diameters less than 40 microns. -In the text "Industrial Gums - Polysaccharides and Their Derivatives", edited by Whistler and BeMiller ~Academic~Press, New York and London - 1973), on page 268 it is stated that gum ghatti is a better emulsifier than gum arabic. On page 352 of the same text, it is stated that Psyllium seed gum is recommended as a replacement for , gum arabic as an emulsifier, and on page 357, flax seed gum is similarly recommended. Carboxy methyl cellulose, which in many ways can be considered to be a synthetic gum, is often recommended as a replacement for gum arabic in emulsions.
~ The inventors herein have attempted to produce aqueous résole dispersions by procedures analogous to the process of this invention, and using, in turn, Psyllium seed gum, flax seed gum, and carboxy methyl cellulose as the interfacial agent. In each case, the results were unsatisfactory. No phase înversion was obtained; there-fore, no resin-in-water dispersion was produced.
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2.

.-; : . , ,~ . , . . . , , ~;, Wha~ the foregoing discussion demonstrates is that the usefulness and effectiveness of a gum in the produc~ion of aqueous resole dispersions cannot be pre-dicted from its known performance in the end-use appli-cations in which gums have heretofore been employed.
The invention provides an aqueous dispersion containing dispersed particles of a phenolic resole, gum ghatti, and a thickening agent. The invention also pro~
vides a process for producing such dispersions which com-prises reacting a phenol with an aldehyde in the presenceof a basic ca~alyst, said reaction being carried out for a period of time and at a temperature sufficient to pro-duce à substantially water-insoluble phenolic resole, and dispersing said phenolic resole in an aqueous medium in the pr~sence of gum ghatti and a thickening agent.
The aldehydes employed to produce the phenolic resole can be formaldehyde or a material that provides the reaction mixture with formaldehyde or its equivalent such as para-formaldehyde or hexamethylenetetramine, acetalde-hyde, furfural, acrolein, or other aldehyde. Formaldehydeis preferred, especially as the aqueous solution known as "formalin".
- The phenols that can be employed to produce the resoles employed in the invention include unsubstituted phenol (i.e., monohydroxybenzene), and various substituted monohydric and polyhydric phenols. Illustrative examples include o-, m- and p-cresol, ethylphenol, propylphenol, para-tert.-butylphenol and other ~utylphenols, amylph~nol, octylphenol, cyclohexylphenol, nonylphenol, dodecylphenol, and-other alkylphenols; para-phenylphenol; styrenated

3.

~5~673 9617 phenol; halogenated phenols such as chloro- and bromophenols;
hydroquinone; and bisphenols such as 2,2~bis(4-hydroxy-phenyl)propane (bisphenol-A) and bis(4-hydroxyphsnyl) methane.
Monohydric phenols employed will normally be di-or trifunctional. That is, 2 or 3 of the positions ortho and para to the phenolic hydroxyl will normally be unsub stituted. Bisphenols are usually tetrafunctional, although up to 2 of the reactive positions ortho to the phenolic hydroxyl can be substituted.
Ordinarily, from about 0.5 to about 4 moles, and preferably from about 1 to about 3 moles, of aldehyde per mole of phenol will be employed. As is known in the art, more aldehyde is employed when the phenol is a bisphenol -than when a monohydric phenol is used.
In producing a phenolic resoLe, an alkaline cataiyst is employed. Specific illustrative catalysts include alkali metal and alkaline earth metal hydroxides, ~ ~-oxides, or carbonates,such as sodium hydro~ide, potassium hydroxide, barium hydroxide, calcium oxide, sodium carbonate, and the like; ammoniacal compounds such as ammonia, hexamethylenetetramine, and quaternary ammonium hydroxides; and amines such as ethylenediamine, trimethyl-amine, dimethylamine, and N,N-dimethyl ethanolamine.
The catalyst is employed in catalytically sig-nificant proportions, such as, from about 0.007 to about 0.4, and preferably from about O.~Ol to about O.l equiva-lents of catalyst per mole of p~enol.

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4.

~596~3 9617 The aqueous dispersions of the invention are pro-duced by a process which comprises reacting a phçnol with an aldehyde in the presence of an alkaline catalyst to pro-duce a substantially water-insoluble phenolic resole, and dispersing said resole in an aqueous medium in the presence of gum ghatti and a thickening agent.
A convenient way to carry out the process is the following:
Charge the phenol, aldehyde, and catalyst to a reaction vessel having conventional agitation, heat transfer, reflux, and control means. It is convenient to include an inert diluent to act as a reac~ion medium. Water is pre-ferred, and will normally be added with the aldehyde, since aqueous formaldehyde is the aldehyde used in most cases.
The condensation reaction between the phenol and aldehyde is usually initiated by applying external heat to the reaction mixture until the condensation reaction starts.
Thereafter, the exothermic nature of the reaction keeps it going at the beginning of the reaction. Temperature control is normally achieved by refluxing at a controlled pressure, with external heating or cooling being employed as needed.
The condensation reaction is continued until at least a low viscosity resole is produced. The viscosity should be low enough so that, with the shear available in the reaction - vessel, the resole can be broken down into a small particle size resin.
At this point, additional water can be added to the reaction mixture, along with the gum ghatti and thick ening agent. In order to enhance the stability o~ the resole, it is sometimes d~sirable to neutralize the alkaline ~ ~9 6~ 3 catalyst before further processing. The pH of the reaction mixture s~ould normally be about 9 or less, preferably about 3 to about 7.5, and more preferably about 4.5 to a~out 6.5, after the initial phenol/aldehyde condensation reaction is completed, i.e., after neutralization, if required. The particular pH selected depends, in part, upon the nature of the phenol and the end-use application intended for the dis- :
persion.
An important feature of the invention is that the 10 resole is dispersed in water, in the presence of gum ghatti ;-and thickening agent, in situ. That is 3 the resole is dis-persed in water before it is isolated from the reaction mix-ture. If the resole is isolated from the reaction mixture, and then later re-dispersed in water, it will not be possible to obtain nearly as fine a particle size, nor will the dis-persion be as stable.
The gum ghatti and/or thickening agent can be in t~e reaction mixture from the beginning of the phenol/
aldehyde condensation reaction. However, it is preferred to carry out the condensation reaction until a low viscosity resin is produced, and then add gum ghatti, thickening agent, and more water if necessary. (At this point, the resin may still be at least partially soluble in water. The resole may not - become substantially water-insoluble until after neutralization and/or bodying.) Enough water must be present in the dispersion to enable a phase inversion to take place, i.e,, to yield a resin-in-water dispersion (the water being the continuous phase~. Typical maximum resole solids concen-trations are within the range of from about 40 to about 50 weight per cent, determined by measuring the weight loss L
~ ~ 6.

.. .. ~ .. .

~05~673 9617 of a 1.5 gram sample after 3 hours in a 135C. oven.
When the phenol is unsubstituteaL phenol, the maximum per-missible solids content tends to be near the lower end of :~
this range. When the phenol is bisphenol-A, the maximum permissible solids content tends to be near the upper part of the range, and when the phenol is an alkyl phenol, the m~ximum permissible solids content tends to be near the , :.
'~ ' 6A. .

~S96~3 9617 middle of the range. Of course, more water may be employed.
Howev~r, for various commercial reasons (such as the desire to keep shipping costs low), it i~s usually preferred to maintain the water content as low as possible.
As has been pointed out above, the best time to add gum ghatti, thickening agent, and additional water (as needed) to the reaction mixture, is not later than that point in the reaction when a low viscosity resin is produced.
(The condensation reaction is carried out at elevated temper- -~
atures, e.g., 75 to 105C., and at these temperatures the resole will be liquid.) One or two experiments will probably be required to determine the best point at which to add the gum ghatti, thickening agent, and water, for particular resoles. However, phenolic resin chemists, who have been making resoles commercially for 40* years~ are fully capable of determining that point after having read this disclosure.
The dispersion of the resole in water will be effected by applying shear to the reaction mixture contain-ing substantially water-insoluble resole, water, gum ghatti, and thickening agen~. Agi~ation of the reaction mixture is the most convenient way to provide the requisite shear.
The resole must be substantially water-insoluble.
While it varies somewhat, depend-.ing on the exact nature of the resole, normally to be water-insoluble, the resole must have a weight average molecular weight of at least about 400.
The resoles of the invention ca~ have weight average molecular weights of up to about 3000 or more. Weight average molecul~r weight can be determined by known procedures, e.g., see Moore, "J. Poly. Sci., Part A," 2, 835, 1964.

7.

~6l7 1~59~;73 In order to attain the degree of advancement of t~e resole that is desired for t~e end-use application for which it is intended, it is often desirable to subject the resole to elevated temperature for a controlled period of time after addition of gum ghatti, thickening agent, and water> and, if it is done, after neutralization of the catalyst. This treatment is often called "bodying" the resin. It is ordinarily carried out at a temperature of from about 80C. to 95C., for a period of about 5 minutes up to 2 hours or more. When the resole is a th~rmosetting material, the advancement can be followed by periodically testing the resole for its 150C. gel time (e.g., every 15 to 20 minutes) until the desired degree of advancement is attained. Phenolic resin chemists are well acquainted with this concept, and know how much advancement is needed for particular end-use applications.
Gum ghatti and a thickener are employed to produce the dispersions of the invention. Gum ghatti is a naturally occurring plant exudate obtained from the stems of Ano~issue latifolia, a plant that is abundant in India and Sri Lanka (Ceylon). It is a polysaccharide containing D-galactose, mannose, glucuronic acid, and rhamnose units. The gum ghatti is employed in an amoun~ sufficient to form and stabilize a dispersion of resole particles in water. Effec-tive amounts of gum ghatti will ordinarily be found within the range of from about 0.5 to about 5, and preferably from ~;~
about 1 ~o about 3, parts by weight, per 100 parts by weight of phenol charged to the reaction mixture.

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,, " , . . . .. .. . . . . .. . .

~S9673 9617 '''' , The thickening agent that is employed can be one or more of the following materials: gums such as guar gum, gum carregeenin, algin gum, locust bean gum; and water-soluble polymers such as ethylene-maleic acid copolymer, ionomers, poly(acrylamide), methyl vinyl ether-maleic anhydride copolymer; and any other water-soluble polymeric material that increase~ the viscosity of water and is com-patible with the other components of the dispersion.
The thickening agent is employed in an amount sufficient to increase the viscosity of the dispersion to at least about 500 centipoises at 23C. As a general rule, an effective amount of thickening agent will usually be found within the range of from about 0.1 to about 1, and prefer-ably from about 0.25 to about 0.8, parts by weight, per 100 parts by weight of phenol charged to the reaction mixture.
The individual phenolic resole particles contained in the aqueous dispersions of the invention can be smaller - ~ 3 and more uniform in size than those of the phenolic disper-sions produced using gum arabic as the interfacial agent.
For instance, dispersions produced in accordance with the invention can have particles having virtually all of their diameters below 5 microns, with their average diameters being between about 1 and 3 microns. While the invention does include dispersions whose particles are larger (for instance, wherein the average particle diameters are below about 12 microns, with virtually all the particle diameters being below about 25 microns), for many end use applications the utility is enhanced when the particle siæe is smaller and more uniform. Examples of such end use applications include adhesive and coating applications wherein the phenolic dis-9 .
' , :, ,.......... . . - :,~ . . .. .

~5~673 9617 persion is employed in conjunction with an addition polymer latex such as an acrylic latex.
The smallest and most uniform particle size dis-persions that we have made to date using gum arabic as the interfacial agent, have particles whose diameters vary from about 5 to about 10 microns.
The following Examples illustrate the practice of the invention:

10 Into a five-liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer, and heating mantle, there was charged the following:
Phenol 1200 grams 40 per cent Aqueous Formaldehyde 1668 grams 25 per cent Aqueous Sodium Hydroxide 100 grams This mixture was heated, with agitation, to a temperature of 70C., whereupon the heating mantle was removed and the re-action mixture allowed to rise in temperature to atmospheric reflu~ through its exothermic heat o reaction. (The re-20 action temperature at atmospheric reflux is about 102C.~ ;
The initial vigor of the reaction was moderat~d as necessary to prevent excessive flooding of the condenser by cooling with a cold water bath.
This mixture was allowed to reflux for about 30minutes. At the end of this reflux period, the following were added in the order listed:
Water 720 grams Gum Ghatti 24 grams Guar Gum 6 grams 20 per cent Aqueous Sulfuric Acid 138 grams After mixing for five minutes, the pH was found to be 5 2 10, .

.
.
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, :. . , . : . . .:
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...... ; . .

~5~6~3 The contents of the flask were then heated to 80C., and held at about 80C. for forty minutes. At the end of this forty minutes, the contents of the flask were cooled to below 30C. and discharged into a suitable con-tainer as a dispersion of phenolic resole in water having the following properties:
Solids 41.2 percent pH 5.5 ~;
Hot Plate Gel (150~C.) 110 seconds Viscosity (Brookfield) 1050 centipoises at 25C. ;
Particle Size 1-3 microns (by microscope examination) No significant settling of the resin particles ~
was apparent af~er 16 weeks at room temperature. The dis- ;
persion could be infinitely diluted with water.
The guar gum used in the above example is a commercial product sold by Stein, Hall & Company, Inc., under the trade mark designation "Jaguar J2Sl."
The gum ghatti employed in this and other Examples was "Grade 1", and was obtained either from Stein, Hall or from Matheson, Coleman & Bell.

This experiment illustrates the effect of using gum ghatti alone, without the thickening agent.
The apparatus and procedure of Example 1 were used with the exception that no guar gum was added. The follow-ing were charged to the five-liter flask: `
Phenol 1200 grams `~
40 percent Aqueous Formaldehyde 1668 grams 25 percent Aqueous Sodium Hydroxide 100 grams 11 .

lOS9G73 ; This mixture was heated to 71C., the heating mantle removed, and the temperature allowed to rise by the exothermic heat of reaction. The mixture was allowed to react for about 30 minutes at atmospheric reflux. At the end o~ the 30 minutes, the following were added in the order listed:
Water 720 grams Gum Ghatti ~4 grams 20 per cent Aqueous Sulfuric Acid 135 grams The pH of the resulting mixture was adjusted to 5.6 by addition of 10 grams of 25 per cent aqueous sodium hydroxide.
The contents of the flask were then heated to about 80C., held at that temperature for about 60 minutes, and ~ cooled to below 30C. The resulting dispersion of a phenolic resole had particles ranging from about 2 to about 30 microns.
This was Ln marked contrast to the 1-3 microns sized particles in the product of Example 1. Because of the larger particles and the lower viscosity of the product of this experiment, settling was rapid.

Prepara~ion of Phenolic Dispersion (Bisphenol-A Derived~
Using Ghatti Gum With Guar Gum Into a 5-liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer, and heating mantle, ~here was charged 1200 grams of Bisphenol-A, 924 grams of rl ' .
aqueous formaldehyde (40 per cent), and 14.4 grams of aqueous sodi~m hydroxide (25 per cent). The mixture was heated to about 90C. whereupon the heating mantle was removed and the .
; mixture allowed to reach a stage of reflux at 95C., under ~acuum such that the pressure on the reaction mixture was

5-6 inches of mercury below atmospheric. The mixture was then refluxed for 60 minutes at 95C. with additional heat ... .
12.

,, ~5967~ 9617 provided as necessary. At the end of the 60-minute period, 864 grams of water, 24 grams o-f ghatti gum, and 3.6 grams of guar gum (Jaguar 507 - Stein,Hall & Company, Inc.) were added to the contents of the flask with vigorous agita~ion. Then 10.8 grams of 42 per cent aqueous phosphoric acid were added to the flask and the pH adjusted to 6.2. The contents of the flask were then brought to a temperature of about 90C. and maintained at this temperature for 90 minutes. At the end of this time, ~he contents of the reaction flask were cooled to a temperature below 50~C. and discharged as a resin-in-water dispersion having a solids content of 48 per cent by weight and a 150C. gel of 155 seconds. The dispersion viscosity (Brookfield spindle #2 at 30 rpm) was 1050 cps. and the resin ~t particle size was substantially between 2 and 5 microns. This material did not s~parate at all after standing for 13 weeks.

Preparation of Phenolic Dispersion (Bisphenol-A Derived) Without Use of Thickening Agent A phenoli~ dispersion was prepared substantial1y as in the preceding Example 2, except that no guar gum was added to the reaction mixture. The viscosity of this dis-~ .
persion (Brookfield spindle #2 at 30 rpm) was 150 cps. and ~r the resin particle size ranged from 2 to 25 microns with an average size of about l0 microns. This material settled to the extent of about 25 per cent after standing ~or 3 weeks.

Preparation of Phenolic Dispersion (Bisphenol-A Derived~
Locust Bean Gum Replacing Guar G~m Into a 5-liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer, and heating mantle, there was charged l000 grams of Bisphenol-A, 770 grams of aqueous ~ormaldehyde (40 per cent~, and 12.2 grams of ''', - 13.
..~

', . ' " ' ~ 596~73 aqueous sodium hydroxide (25 per cent). The mixture was heated to 90C. whereupon the heating mantle was removed ;
and the mixture allowed to reach a stage of reflux at 95C. under an absolute pressure of 5-6 inches of mercury below atmospheric. The mixture was then refluxed for 60 minutes at 95C. with additional heat provided as necessary.
At the end of the 60-minute period, 770 grams of water, 20 grams of ghatti gum, and 6.5 grams of locust bean gum (175 --mesh - from Stein,Hall) were added to the contents of the flask with vigorous agitation. Then 8.0 grams of aqueous phosphoric acid (42 per cent) were added to the flask and the pH adjusted to 6.5. The contents of the flask were then brought to a temperature of about 90C. and maintained at this temperature for 120 minutes. At the end of this time, the contents of the reaction flask were cooled to a temperature below 50C. and discharged as a resin-in-water dispersion having a solids content of 48 per cent by weight and a 150C. hot plate gel time of 171 seconds.
The viscosity of the dispersion was 2000 cps. (Brookfield spindle ~2 at 30 rpm), and the dispersed resin particle size was substantially between 2 and 5 microns in diameter.
This material did not settle significantly after standing for 8 weeks.
EX~MPLE 4 Preparation o~ Phenolic Dispersion (Bisphenol-A Derived) With Sodium Alginate Replacing Guar Gum The same formulation and procedure as Example 3 was followed, except that 4.5 grams of sodium alginate ("Alginic acid, Sodium Salt - Practicall' from Matheson, Coleman & Bell) replaced 6.5 grams of locust bean gum. The dispersion's viscosity (Brookfield spindle ~2 at 30 rpm) was 770 cps. and 14.

1~59~73 the resin particle size was substantially between 2 and 5 microns in diameter. This material did not settle at all after standing for 3 weeks. After 8 weeks, settling was less than 5 per cent.

Preparation of Phenolic Dispersion (Bisphenol-A Derived) "~MA-81" (Ethylene/Maleic Anhydride Copolymer from ~lonsanto) Replacing Guar Gum The same procedure and formulation as Example 3 were used', except 7.0 grams o-f EMA-81 replaced 6.5 grams of locust bean gum and no phosphoric acid was used to neutralize the reaction mixture. The dispersion's viscosity was 16,400 cps. and the resin particle size was substantially between 2 and 5 microns in diameter. This material did not settle after standing for 7 weeks.
Probably, a lower'concentration of EMA-81 would be desirable in some cases, in order to yield a dispersion ~'~
having a lower viscosity, which would be easier to handle.

Preparation of Phenolic Dispersion (Alkyl Phenol Derived) Using Ghatti Gum and Guar Gum Into a 5-liter, round bottom flask, equipped wi~h a reflux condenser, agitator, thermometer and heating mantle, there was charged 1200 grams of para-t-butylphenol, 1200 grams of aqueous 40 per cent formalin, and 36 grams of aqueous sodium hydroxide (25 per cent). The mixture was heated to 73C., whereupon the heating mantle was removed and the mixture allowed to reach 80C., at which temperature it was kept for 2 hours. At the end of this period, it was heated to atmos-30 pheric reflux and kept there for 60 minutes. At the end of "
this period, 780 grams of water, 24 grams of ghatti gum, and 4.8 grams of guar gum were added to the contents of t'he i~
.
,,; ;

1~9S96~3 flask with vigorous agitation. Then 10.8 grams of aqueousphosphoric acid (42 per cent) were added and the pH adjusted to 6.7. The contents of the flask were then brought to 95C. and maintained at this temperature for 2 hours. At the end of ~his time, the contents of the flask were cooled to a temperature below 50C. and discharged as a resin in-water dispersion. The dispersion's viscosity (Brookfield spindle #2 at 30 rpm) was 890 cps. and the resin particle size was substantially between 5 and 18 microns. This material did not separate after standing for 12 weeks.
In the experiment of Example 6, the phenollform-aldehyde condensation reaction was carried out at a lower temperature than the other Examples herein, for the following reasons:
The condensation reaction between the t-butylphenol and formaldehyde is relatively slow because of the low solubility of t-butylphenol in water. The resole products of this reaction which contain three or more phenol nuclei contain hyperacidic phenolic hydroxyls, and therefore these products tend to lower the pH of the reaction mixture more than "conventionall' resoles. For these two reasons, more alkali is required for catalysis. However, the higher con-centration of alkali tends to increase ~he incidence of side reactions, especially the Cannizzaro reaction. But, the reacti.on rate of the desired condensation reaction is reduced by a much lesser degree than that of the Canniæzaro reaction by lowering the temperature. Therefore, a lower reaction temperature is used, which, although it requires a longer reaction time, serves to reduce the incidence of side reactions.

16.

1~59&i73 EXAMPLE 7 `
Preparation of Phenolic Dispersion (Phenol-Alkyl Phenol Derived) Using Ghatti Gum and Guar Gum Into a 5-liter, round bottom flask, equipped with a reflux condenser, agitator, thermometer and heating mantle, there was charged 600 grams of phenol, 600 grams of p-nonyl-~ phenol, 933 grams of aqueous formaldehyde (40 percent), and 24 grams of aqueous sodium hydroxide (25 percent~. The mix- :
ture was heated to 85C. whereupon the heating mantle was lowered and the mixture allowed to reach a stage of atmos-pheric reflux through its exothermic heat of reaction. The mixture was then re1uxed for 65 minutes. At the end of th~s ;~
period, 720 grams of water, 24 grams of gum ghatti, and 4.8 .
grams of guar gum were added to the contents of the flask.
Then there was added to the flask 16 grams of aqueous phos-phoric acid (42 percent) and the pH of the mixture adjusted to 6.65. The contents of the flask were then brought to ~5C. and maintained at this temperature for one hour. At the end of this ,time, the contents of the flask were cooled to a temperature below 50C. and discharged as a resin-in-water dispersion. The viscosity (Brookfield spindle #2 at 30 rpm) of the dispersion was 2360 cps. and the resin `
particle size was substantially between 2 and 6 microns. .-The dispersion did not separate after standing 12 weeks.

CONTROL 3 -;
This is an experiment illustrating the use of gum ghatti and "Darvan #2" (trade mark designation of R. T.
Vanderbelt Company) in the preparation of a "Vinsol" modified phenolic resole in dispersion form, as described in the Hercules brochure on Vinsol Resin as Modifier of Phenolic Resins J copyright 1955, page 23.

17.

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~59673 9617 Into a five-liter, round bottom flask equipped with a reflux condenser, agitator, thermometer, and heating mantle, there was charged the following:
Phenol 1005 grams Vinsol 495 grams 40 per cent Formaldehyde884 grams Water 67.5 grams Paraformaldehyde 350 grams This mixture was heated to atmospheric reflux with continuous stirring, and held until the paraformaldehyde had dissolved.
The contents of the flask were then cooled to 26C. and the following added:
Ammonium Hydroxide 29.6 per cent 318 grams Gum Ghatti 27 grams Darvan #2 4.5 grams The resulting mixture was then heated to a temperature of ` -75C., whereupon the heating mantle was removed, and the temperature allowed to rise through the exothermic heat of reaction. When the temperature reached 98C., additional heating was used to bring the mixture to atmospheric reflux.
Reaction at atmospheric reflux was continued for a total of three hours. The mixture was the~ cooled to below 40C.
The reswlting product was an aqueous dispersion of a phenolic resin having a particle size range from about 2 microns up to about 160 micrvns. Upon standing for two days at room temperature, the dispersed resin phase had - settled, and could be redispersed only with vigorous stirring.
"Darvan #2" is supplied by the R. T. Vanderbilt Company. It i8 the "sodium salt of polymerized substituted benzoid alkyl sulfonic acids."

~ ~ S~ ~ 3 This experiment differs from Control 3 in that the "Vinsol" is omitted.
The apparatus and procedure o~ Control 3 were used.
The following were charged to the five-liter flask:
Phenol 1005 grams 40 per cent Formaldehyde 884 grams Water 67.5 grams Pàraformaldehyde 307.5 grams The above mixture was heated at atmospheric reflux until the paraformaldehyde had dissolved. After cooling to 34C., the following were added:
Ammonium Hydroxide 29.6 per cent 318 grams Gum Ghatti 27 grams -Darvan #2 4.5 grams The temperature of the mixture rose through the exothermic heat of reaction. When atmospheric reflux began, the reaction was moderated by cooling with a cold water bath as necessary to control foaming and prevent flooding of the condenser.
After three hours a~ atmospheric reflux, the contents of the flask were cooled to below 40C.
Microscope examination of the~phenolic dispersion obtained show a wide range of particle sizes up to 160-200 microns in diameter with a large percentage of particles being 50 microns or larger.

The dispersions of this invention are stable for extended periods of time. For instance, in most cases, no appreciable settling of the resole particles occurs upon standing for 4 weeks, and in many cases, much longer, as the foregoing Examples illustrate.

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Claims (11)

WHAT IS CLAIMED IS:

1. An aqueous dispersion containing dispersed particles of a phenolic resole in water, gum ghatti, and a thickening agent, substantially all of said particles having diameters below about 25 microns, wherein the molecular weight of said resole is such that said resole is substantially water-insoluble, wherein said gum ghatti is employed in an amount sufficient to stabilize said dis-persion of resole particles in water, and wherein the thickening agent is employed in an amount such that the viscosity of said dispersion at 23°C. is at least about 500 centipoises.

2. The aqueous dispersion of claim 1 wherein said phenolic resole is the base-catalyzed reaction pro-duct of a phenol and formaldehyde, wherein the average diameter of said particles is below about 12 microns, and wherein the proportion of said resole in said dispersion is not greater than about 50 weight per cent, based on weight of resole plus water.

3. The aqueous dispersion of claim 2 wherein said phenolic resole has a weight average molecular weight within the range of from about 400 to about 3000.

4. The aqueous dispersion of claim 2 wherein said phenol is at least one member of the group consisting of monohydroxybenzene, alkylphenol, and 2,2-bis(4-hydroxy-phenyl)propane.

5. The aqueous dispersion of claim 2 wherein substantially all of said particles have diameters below about 5 microns.

6. The aqueous dispersion of claim 5 wherein said particles have average diameters below about 3 microns.

7. The aqueous dispersion of claim 2 wherein said thickening agent is selected from the group con-sisting of guar gum, gum carrageenan, algin gum, locust bean gum, and water-soluble ethylene-maleic anhydride copolymers.

8. The aqueous dispersion of claim 2 wherein the gum ghatti is employed in an amount of from about 0.5 to about 5 parts by weight, and wherein the thickening agent is used in an amount of from about 0.1 to about 1 parts by weight, per 100 parts by weight of phenol employed to produce said resole.

9. A process for producing an aqueous disper-sion of phenolic resole particles in water, which process comprises reacting a phenol with an aldehyde in the presence of a basic catalyst for a period of time and at a temper-ature sufficient to produce a substantially water-insoluble phenolic resole, and dispersing said phenolic resole, in situ, in an aqueous medium containing gum ghatti and a thickening agent, wherein said aqueous medium contains sufficient water to enable a phase inversion to occur during said dispersing step, thereby to produce a disper-sion of phenolic resole in water, wherein said gum ghatti is employed in an amount sufficient to form and stabilize said dispersion of phenolic resole particles in water, and wherein said thickening agent is employed in an amount such that the viscosity of said dispersion at 23°C. is at least about 500 centipoises.

10. The process of claim 9 wherein said aldehyde is formaldehyde.

11. The process of claim 9 wherein said process includes the steps of:
(a) reacting a phenol with an aldehyde in a reaction mix-ture containing a basic catalyst for a period of time sufficient to produce a resole;
(b) adding to said reaction mixture gum ghatti, a thick-ening agent, and sufficient water to enable the production of a resole-in-water dispersion; and (c) thereafter subjecting the reaction mixture to elevated temperature for a period of time sufficient to increase the weight average molecular weight of said resole to a value within the range of from about 400 to about 3000;
provided that the pH of said reaction mixture is below about 9 prior to said step (c).