This invention is directed to hemi-formals having the following formulas: ##STR1## wherein b is 1 to about 5, c is 1 to about 3, d is 0 to about 2, the sum of c and d does not exceed 3 and is equal to or greater than 1 and n has a value equal to or greater than 1. These materials can be used to manufacture phenolic resins and are adaptable to liquid injection molding processes.

This application contains subject matter disclosed in U.S. application Ser. 
No. 242,995, filed Mar. 12, 1981, now abaondoned in favor of 
continuation-in-part U.S. patent application, Ser. No. 340,695, filed Jan. 
19, 1982. 
This invention is directed to hemiformals of methylolated phenols. The 
hemiformals are formed by the reaction of formaldehyde with the phenolic 
hydroxyl groups and methylol groups of methylolated phenols. They are 
preferably formed from a reaction mixture of formaldehyde and phenol in 
the presence of a divalent metal catalyst, wherein methylolated phenols 
are formed in situ in the reaction mixture. This invention is directed in 
particular to methylolated hemiformals of phenol which are stable and can 
be stored for considerable periods of time. Contemplated are liquid 
hemiformal compositions which are curable to a phenolic resin when 
utilized with conventional phenol aldehyde resin curing catalysts. 
The production of hemiformals of phenol have been speculated about in the 
literature for a considerable period of time. Illustrative of such 
literature is Walker, FORMALDEHYDE, 3rd Edition, published by Reinhold, 
Publishing Corporation, New York, (1964), pages 305, 306 wherein the 
following is stated: 
"In the absence of added catalysts, anhydrous formaldehyde and 
paraformaldehyde dissolve in molten phenol without apparent reaction to 
give clear, colorless solutions which smell strongly of formaldehyde. In 
such solutions, it is probably that some solvation takes place and 
hemiformals, such as C.sub.6 H.sub.5 OCH.sub.2 OH, C.sub.6 H.sub.5 
OCH.sub.2 OCH.sub.2 OH, etc., are present. However, studies of 
formaldehyde polymers have demonstrated that phenol is a solvent for these 
compounds and the majority of the dissolved formaldehyde in phenolic 
solutions may be in the polymerized state. Studies by Fitgerald and 
Martin.sup.44 involving the measurement of hydroxyl ion concentrations in 
dilute, alkaline, aqueous formaldehyde in the presence and absence of the 
sodium phenolate of mesitol indicate that hemiformal concentrations are 
too small to be measured in this way. However, in our opinion hemiformal 
formation with a hindered phenol, such as mesitol, would be similar to 
hemiformal formation with tertiary butyl alcohol which does not show any 
appreciable solvation of formaldehyde. There is a definite analogy of 
nonaqueous phenol formaldehyde solutions to solutions of formaldehyde in 
alcohols and other polar solvents. According to Reychler.sup.102, a small 
percentage of sodium phenolate catalyzes the solution of linear 
formaldehyde polymers in phenol, just as sodium alcoholates catalyze 
solution in methanol, ethanol, and other alcohols. That 
##STR2## 
hemiformals are produced is also indicated by the isolation of methyl 
phenol formal from an acid-catalyzed reaction of phenol with formaldehyde 
solution containing methanol.sup.20." 
FNT .sup.44 Fitzgerald, J.S.; Martin, R. J. L., Australian J. chem. 8 194-214 
(1955). 
FNT .sup.102 Reychler, A., Bul. Sot. Chim. (4), Vol. 1, pp 1189-95 (1907): 
Chem. Abs. 2 1266 (1908). 
FNT .sup.20 Breslauer, J., Pictet, A., Berichte, 40, 3785 (1907). 
One of the difficulties with the conclusion which is raised in the Walker 
article is that the hemiformal is produced from an acid-catalyzed reaction 
of phenol with a formaldehyde solution containing methanol. It is 
notoriously well known that acids act to catalyze the reaction of phenol 
with formaldehyde to effect normal alkylation of phenol by formaldehyde to 
produce the phenolic resins. Thus what is seen by Walker as a suggestion 
of the existence of the hemiformal may be nothing more than the known 
reaction between methanol and formaldehyde in the presence of an acid 
catalyst to form a product which is subsequently reacted with phenol to 
yield an ether product which is characterized as the final product of the 
reaction. Actually a reaction between formaldehyde and phenol to produce 
the hemiformal would have yielded an equilibrium reaction and this is 
totally absent from the reaction characterized by Walker, suggesting again 
that in the theoretical reaction disclosed by Walker the formaldehyde is 
first stabilized with methanol and then the product is reacted with 
phenol. 
Bakeland and Bender in an article in "Industrial and Engineering Chemistry" 
Volume 17, No. 3, pages 225-237 (1925) make the following statements 
concerning the formation of a theoretical hemiformal of phenol: 
"The phenol first unites directly with the aldehyde to form a mixed 
ether-alcohol compound (XXXIII), and the resulting ether group very 
rapidly rearranges to the phenol. 
##STR3## 
Thus, Bakeland and Bender clearly indicate that if the hemiformal exists it 
is at best a transitory material which is unstable under the conditions at 
which it was produced and, at best, is a theoretical composition 
constituting an intermediary in the generation of phenolic resins. 
Strupinskaya et. al. in Plast. Massy 1968, (12), at pp 18-20 describe the 
preparation of a product by the absorption of formaldehyde into molten 
phenol at a formaldehyde to phenol ratio of 3:10. This corresponds to a 
formaldehyde to phenol mole ratio of 0.94:1. The source of formaldehyde 
was a converter gas stream containing about 10% methanol and analysis of 
the product showed it to contain up to 8% methanol. The presence of 
methanol suggests that this reference refers to a methanol stabilized 
product similar to that disclosed in Walker cited above, wherein 
formaldehyde reacts with methanol and subsequently reacts with phenol to 
form the ether product. The low formaldehyde to phenol ratio also suggests 
that hemiformals having average formaldehyde to phenol ratios higher than 
1:1 would probably not have been formed in this process. 
In Belgium Pat. No. 667,360, issued on Nov. 16, 1965, to Chemische Werke 
Huels A. G., is disclosed treatment of various hydroxy-compounds, 
including phenol, with monomeric formaldehyde, at a formaldehyde to phenol 
ratio of 1:1. The low formaldehyde to phenol ratio would indicate that any 
hemiformal formed would have no more than an average of one formaldehyde 
moiety structure in the hemiformal chain structure. As disclosed in 
Bakeland and Bender, cited above, hemiformals are known in the art as 
transitory or unstable species and would be expected by one of ordinary 
skill to be increasingly unstable as the length of the hemiformal chain 
increases. It would, therefore, be expected that additional formaldehyde 
added in the Huels process would react with the phenol at another site on 
the aromatic ring, such as at the para or ortho-position, rather than 
forming hemiformals with a higher formaldehyde to phenol ratios. A person 
normally skilled in the art would, therefore, expect that hemiformal 
compositions having formaldehyde to phenol ratios greater than 1:1, 
wherein hemiformal chains having more than one formaldehyde moiety are 
formed, would be unstable, forming other phenol-formaldehyde resinous 
products or dissociating to form free formaldehyde. 
The first time where it has been established that hemiformals of phenol 
having an average molar ratio of formaldehyde to phenol have been produced 
which have a recognized stability, are isolable, and can be utilized in 
the formation of a variety of products, particularly phenol-formaldehyde 
resins, is in copending U.S. patent application, Ser. No. 340,719 filed on 
Jan. 19, 1982, by F. Covitz, G. Brode, and S. Chow wherein liquid 
hemiformal compositions of phenol produced by the reaction of formaldehyde 
and phenol are disclosed. The hemiformals therein disclosed are reaction 
products of phenol and formaldehyde wherein the reaction occurs between 
the formaldehyde and the phenolic hydroxyl group to form a liquid 
hemiformal having the formula; 
##STR4## 
wherein n is a positive number greater than 1, preferably a number greater 
than 1 and less than about 5, and most preferably a value of about 1.2 to 
about 2.5. These hemiformals are liquid and of low viscosity. 
Also disclosed are hemiformal compositions comprising the hemiformal of 
Formula (I) in combination with up to about 50 mole percent, based on the 
total moles of the composition, of another hemiformal having the following 
formula: 
##STR5## 
wherein n is as described above, R is any substitutent typically employed 
in conjunction with a phenolic structure and x has a value of from 1 to 
about 3. With respect to R, it is preferably a monovalent radical which 
includes alkyl of from about 1 to about 18 carbon atoms, cyclo-alkyl from 
5 to 8 carbon atoms, aryl containing from 1 to about 3 aromatic rings, 
aralkyl, alkaryl, alkoxy containing from 1 to about 18 carbon atoms, aroxy 
containing 1 to 3 aromatic nuclei, halide such as chloride, bromide, 
fluoride, and iodide; alkyl sulphido having from 1 to about 18 carbon 
atoms, aryl sulphido having from 1 to about 3 aromatic nuclei, and the 
like. 
Hemiformals derived from oil-modified phenols such as linseed oil or tung 
oil-modified phenols are also disclosed. 
As disclosed in the above cited application, the hemiformal-forming 
reaction is preferably carried out in the absence of any catalyst. 
Generally, a catalyst adversely affects the formation of hemiformals, 
causing the formation of other phenol-formaldehyde resinous products. It 
has been found, however, that in the presence of a divalent-metal 
catalyst, more fully defined below, phenol and formaldehyde react to form 
equilibrium mixtures of hemiformals of phenol and hemiformals of 
methylolated phenol. This is unexpected in light of the common knowledge 
in the art that catalyzed reactions of phenol and formaldehyde generally 
form phenol-formaldehyde resinous products that are condensation products 
of phenol and formaldehyde, and typically do not form phenol hemiformals. 
It is also unexpected that the novel hemiformals of methylolated phenol 
that are formed in this reaction are stable, and isolatable and are not 
transitory materials that immediately form condensation products. This 
invention represents the first time that such hemiformals of methylolated 
phenol have been identified. The hemiformals of the invention can also be 
used in the formation of a variety of products, among which are, of 
course, phenol-formaldehyde resins. 
This invention is directed to the manufacture of a new composition of 
matter which contains at least one of the following structures: 
##STR6## 
In the above formulas, b is 1 to about 5, c is 1 to about 3, d is 0 to 
about 2, the sum of c and d is at least 1 and no greater than 3 and n has 
a value greater or equal to 1, preferably from 1 to about 5, most 
preferably about 1.2 to 2.5. It is understood that these numbers represent 
average values and a hemiformal composition will actually comprise a 
mixture of hemiformals as defined above. 
This invention also encompasses the utilization of the hemiformals 
discussed above in combination up to about 50 mole percent, based on the 
total moles of the composition, with substituted hemiformals having at 
least one of the following structures; 
##STR7## 
wherein n, b, c, d, are defined as above, R is any monovalent substitutent 
typically employed in conjunction with a phenolic structure, x has a value 
of from 1 to about 3 and the sum of c and d is at least 1 and not greater 
than 3, and the sum of c, d and x is at least 1 and not greater than 5, 
wherein with respect to the R substitution at least 2 of the ortho- or 
para-positions relative to the OH or --O(CH.sub.2 O).sub.n H groups are 
free. With respect to R, it is preferably a monovalent radical which 
includes alkyl of from about 1 to about 18 carbon atoms, cycloalkyl from 5 
to 8 carbon atoms, aryl containing from 1 to about 3 aromatic rings, 
aralkyl, alkaryl, alkoxy containing from 1 to about 18 carbon atoms, aroxy 
containing 1 to 3 aromatic nuclei, halide such as chloride, bromide, 
fluoride, and iodide; alkyl sulphido having from 1 to about 18 carbon 
atoms, aryl sulphido having from 1 to about 3 aromatic nuclei, and the 
like. The hemiformals of Formulas V or VI should not exceed the molar 
concentration, in the preferred embodiment, of the unsubstituted 
hemiformals of Formulas III or IV. One of the advantages of the utilizing 
of the substituted hemiformals of Formulas V or VI in combination with the 
unsubstituted hemiformals of Formulas III or IV is that the former tend to 
alter the properties of any resulting phenolic resin which is derived from 
the combination of the two, such property changes being of the kind which 
allows for a maximum utilization in the manufacturing of a variety of 
phenolic resin type products. For example the halogen substitution will 
enhance the flame retardency of the resultant phenolic resin. A aryl-alkyl 
substitution which contains a hydroxyl group as well, such as bisphenol A, 
will provide a phenolic resin which is a superior coating resin and will 
possess better color properties. Also, a diphenol such as bisphenol A, has 
an additional phenolic hydroxy group, providing another site for 
hemiformal production. Preferably the substituted phenolic hemiformals 
shown in Formulas V or VI should have at least a functionality of two. 
That is it should, with respect to the R substituent only, have at least 
both ortho-positions or have an ortho- and a para-position open, relative 
to the --OH or --O(CH.sub.2 O).sub.n H group. This allows for chain growth 
and cross-linking reactions to occur as the hemiformals of the invention 
are cured. The various substituents in Formulas V and VI, as defined as R 
above, impart to the final resinous product formed by the coreaction of 
the substituted hemiformals of Formulas V and VI with those of Formulas 
III and IV, properties that would be expected in conventional phenolic 
resin chemistry. 
Mixtures of substituted hemiformals that are derived from oil-modified 
phenols such as linseed or tung oil-modified phenols are also 
contemplated. These modified phenols are prepared by reacting phenol and 
the oil in the presence of an acid ion exchange resin. It is well known 
that modified phenols comprise complex mixture containing phenol and 
various substituted phenols derived from reaction of the phenol with the 
sites of unsaturation in the carbon-chains of the oils. The resulting 
substituted or modified phenol mixture can then be treated with 
formaldehyde in the presence of a divalent metal cation as is described 
below to produce a hemiformal mixture. In using oil-modified phenols to 
make hemiformals, at least 50 mole percent of the phenol used in the 
hemiformal reaction should be unreacted with the oil. 
The methylolated phenol hemiformals of the invention can be prepared by 
reacting formaldehyde and methylolated phenols having the formula 
##STR8## 
where a is 1 to about 3. The formaldehyde may be reacted with the 
methylolated phenol as such, but preferably the hemiformals of the 
invention are formed by reacting a mixture of liquid phenol and 
paraformaldehyde in the presence of a divalent metal cation catalyst as 
more fully described below. In this method methylolated phenols of formula 
VII are formed in situ in the reaction mixture. Paraformaldehyde then 
reacts with the phenolic hydroxy group and the methylol groups of the 
methylolated phenol to form the hemiformals of methylolated phenol 
described above. It is, therefore not necessary to isolate the 
methylolated phenols. 
As mentioned above, in addition to hemiformal production at the methylol 
groups, the phenolic hydroxyl group also participates in 
hemiformal-forming reactions. Thus, in the case where unsubstituted phenol 
is used, an equilibrium mixture is formed comprising a hemiformal of the 
formula; 
##STR9## 
and the novel hemiformals of the invention of the formulas: 
##STR10## 
wherein n, b, c and d are defined as above. 
Thus, unlike the method for forming hemiformal compositions of the above 
cited application U.S. Ser. No. 340,719, wherein hemiformals are formed 
having substantially all of the hemiformal production at the phenolic 
hydroxy group, the method of the present invention, wherein a divalent 
metal cation is used, produces equilibrium mixtures containing hemiformals 
with the hemiformal production at both the phenolic hydroxy and methylol 
groups. 
The methylolated phenol hemiformal compositions of this invention are 
curable and yet stable compositions, typically having a good stability at 
temperatures between about 35.degree. C. to about 55.degree. C. Indeed, 
such materials may even be kept in storage for substantial periods of time 
at lower temperatures or even higher temperatures than the range of about 
35.degree. C. to about 55.degree. C. However, when kept at lower 
temperatures, there is a tendency for formaldehyde to separate from the 
product in varying concentrations, causing the formation of 
paraformaldehyde crystals. At temperatures in excess of 55.degree. C. 
there is an increased chance for the loss of formaldehyde from the 
hemiformal structure which formaldehyde can become available for reaction 
with the benzene ring typically in the ortho- or para-position relative to 
the --OH or O(CH.sub.2 O).sub.n H groups thereby causing the formation of 
phenol-formaldehyde resinous condensation type structures. The rate at 
which that occurs, of course, is dependent upon the temperature at which 
the hemiformal is stored, higher temperatures causing a more rapid 
formation of a condensation-type product with a phenol-formaldehyde 
structure. Formaldehyde which separates into paraformaldehyde type 
structures at temperatures below 35.degree. C., can be restored to a clear 
hemiformal product by bringing the product back up to a temperature of 
between about 35.degree. C. to about 55.degree. C. Thus, products stored 
at lower temperatures wherein crystallization or sedimentation has 
occurred can be utilized in their most effective form by bringing them to 
the moderate temperature of about 35.degree. C. to about 55.degree. C. to 
achieve the products of this invention. 
The hemiformals of this invention are liquid materials having a very low 
viscosity, typically from about 20 to 100 centipoise (Brookfield) when 
measured at about 35.degree. C. to 55.degree. C. 
The hemiformals of methylolated phenol can be made by the reaction of 
paraformaldehyde with liquid phenol. By liquid phenol is meant a phenol in 
solution with a solvent unreactive with phenols or aldehydes; or 
essentially pure molten phenol. The temperature of the reaction is where 
the phenol is liquid. Suitable reaction temperatures are from about 
60.degree. C. to about 100.degree. C., preferably from about 80.degree. C. 
to about 90.degree. C. Liquid mixtures of phenol and substituted phenols 
having the formula 
##STR11## 
where R and x are defined above, can also be used with the proviso that 
the moles of substituted phenol not exceed the moles of unsubstituted 
phenol in the reaction mixture. Some of the substituted phenols or the 
hemiformal products derived therefrom may be solid at the reaction 
temperature. In such a case an unreactive solvent may be used to form a 
liquid solution. 
The reaction takes place in the presence of a divalent metal cation such as 
magnesium, calcium, strontium, barium, zinc, lead, cadmium or mercury, at 
a pH of about 3 to about 8, preferably from about 4 to about 6. Typically 
the metal cation is supplied as a salt or as an alkoxide such as a 
carboxylate salt, or a methoxide or ethoxide of the metal in combination 
with a mild acid in order to achieve the desired pH. 
Suitable salts include the formates, acetates, benzoates, and valerates. 
Examples of these salts include zinc acetate dihydrate, calcium formate, 
manganous acetate, lead acetate and zinc benzoate. 
The catalyst is generally present at a concentration of about 0.2 to about 
1 weight percent, preferably 0.4 to 0.7 weight percent, based on the total 
weight of the reaction mixture. 
The paraformaldehyde can be introduced directly to the liquid phenol. 
Preferably the paraformaldehyde is water-free. 
As stated above it is desirable that the paraformaldehyde be free of water. 
However, providing paraformaldehyde which is free of water is quite 
difficult to do and in the normal case water will be carried along with 
the paraformaldehyde which is provided to the reaction. Usually the amount 
of water which is tolerable in the practice of this invention is that 
amount of water which will provide in association with the hemiformal, a 
water concentration of up to about 15 weight percent, based on the total 
weight of the hemiformal composition. In the preferred embodiment it is 
desirable that the amount of water which is present in the resultant 
hemiformal not exceed about 5 weight percent, based on the total weight of 
the hemiformal composition. 
The reaction between paraformaldehyde and the liquid or molten phenol is 
carried out with stirring so as to effect intimate admixture of the 
reactants and the metal catalyst and to assure uniform reaction. 
The reaction may be carried out at subatmospheric or superatmospheric 
pressures, however, in the usual case one will practice the hemiformal 
reaction at atmospheric pressure conditions. 
Since the catalyzed reactions between paraformaldehyde and liquid phenol to 
make hemiformals of phenol, methylolated phenols and hemiformals of 
methylolated phenol, are exothermic, a water bath may be necessary to 
maintain the reaction temperature. 
As previously indicated, a surprising feature of the invention is that the 
hemiformals of methylolated phenol are very stable materials. By "stable" 
it is meant that at temperatures of between about 35.degree. C. to about 
55.degree. C. the formaldehyde which is in the hemiformal moiety reacts 
insignificantly with the aromatic moiety thereof to produce a condensation 
phenolic resin-like structure. For example data indicates that at a 
temperature of about 35.degree. C. about 0.04 mole percent of the 
formaldehyde present in the hemiformal structure is reacted after twenty 
four hours. When the temperature increases to 55.degree. C. the rate of 
reaction consequently increases. 
The unsubstituted liquid hemiformals of Formulas III or IV, alone or 
combined with the substituted hemiformal of Formulas V or VI above, may be 
easily converted into phenolic resins by utilizing any one of the various 
acid or basic catalysts typically employed in the manufacture of phenolic 
resins by the reaction of phenol with formaldehyde. In order to adjust the 
ratio of formaldehyde to phenol, it may be desirable to add phenol to the 
composition. The addition of phenol to the composition allows one to 
balance out the ratio of formaldehyde to phenol and thereby allows one to 
make either a novalac or resole resin composition. In this case, each of 
the formal moieties that are present in the hemiformal constitutes the 
full equivalent of a formaldehyde molecule and thus one can determine from 
the formaldehyde concentration of hemiformal exactly which type of 
phenolic resin they desire to produce, simply by the addition or lack of 
addition of phenol. Since, the hemiformal is extremely reactive in the 
presence of the acid or basic catalyst it is not necessary to add heat 
when making a phenolic resin from them. Simple addition of the 
phenol-aldehyde resin curing catalyst to the hemiformal with or without 
phenol will result in polymerization and the production of the desired 
phenolic resin.

The following examples are not intended to limit this invention in any way. 
EXAMPLE I 
Methylolated phenol hemiformal was prepared as follows. To a 5 liter 
reaction flask equipped with a thermometer, stirrer and an addition port 
there were charged 1410 grams (15 g-moles) of phenol, 742 grams of 91 
percent paraformaldehyde (22.5 g-moles formaldehyde equivalent) and 10.8 
grams of zinc acetate dihydrate as catalyst. The mixture was stirred and 
heated to 85.degree. C. for about 20 minutes. A mild exotherm ensued; the 
reaction mixture was maintained at from 80.degree. to 90.degree. by 
removal of the external heat source and by occasional cooling with a water 
bath. After the exotherm subsided, heat was reapplied to maintain a 
reaction mixture temperature of 80.degree. to 90.degree. C. until a clear 
solution was obtained; this took from about 1 to 2 hours. Nuclear magnetic 
resonance analysis showed the product to be a mixture of hemiformals of 
phenol and hemiformals of methylolated phenol. 
EXAMPLE II 
This Example illustrates the use of the hemiformal of Example I in a 
thermosetting composition and the curing of the composition to make a 
fiber reinforced composite. 
A solution was formed by dissolving a resole phenol formaldehyde resin in 
lump form in the hemiformal of Example I to give a solution of 70 weight 
percent hemiformal and 30 weight percent resole. The formaldehyde/phenol 
ratio, of the hemiformal was 1.5 and the viscosity was 1,500 centipoise 
(Brookfield) at 40.degree. C. 
The resole was formed by reacting an aldehyde and phenol at an aldehyde to 
phenol ratio equal or greater than one in the presence of an alkaline 
catalyst. The resole had an Inclined Plate Flow of 40-90 mm at 125.degree. 
C. The Inclined Plate Flow was determined by compressing a one gram sample 
of the resole to a pellet 12 to 13 mm in diameter. This pellet was placed 
on a glass plate and heated for three minutes in a 125.degree. C. oven. 
The plate was then tilted to a 60.degree. angle and heating continued for 
an additional 20 minutes. The distance, measured in mm, the resin 
travelled is known as the Inclined Plate Flow. This value reflects the 
melt viscosity and the cure rate of the resin. 
A reactive liquid prepolymer was prepared by adding phenol and sulfuric 
acid to the above liquid solution to form a liquid prepolymer containing 
phenol sulfonic acid. The added phenol to sulfuric acid weight ratio was 9 
and the reactive liquid prepolymer contained 0.1 weight percent, based on 
the weight of the reactive liquid prepolymer, of the added phenol-sulfuric 
acid catalyst. The catalyzed mixture was then charged into a mold 
containing a fiber-glass mat. The mold was placed in a press and heated to 
curing a temperature of 120.degree. C. to 150.degree. C. and cured for 8 
minutes. The product was a cured thermoset composite. The glass mat was 
type AKM available from PPG Industries, Inc., Pittsburgh, Pa. The glass 
content of the composition was 63.6 weight percent based on the cured 
weight of the composite.