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Description  |
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This invention relates generally to polyurethanes and more particularly, to
a new process for the preparation of novel dispersions of aminoplasts, and
to dispersions which can be obtained by this process and to their use as
reaction components for polyisocyanates in the production of polyurethane
resins by the isocyanate polyaddition process.
It is known that free N-methylol groups in both low and high molecular
weight aminoplast condensates are very readily etherified by alcohols in
the presence of catalytic quantities of acids [H. Staudinger and K.
Wagner, Makromolekular Chemie, Volume XII, page 173 (1954)]. It is well
known that, in the presence of larger quantities of alcohols, such
etherification reactions are frequently used commercially for the
production of lacquers, e.g. from etherified urea-formaldehyde
condensates. The extreme ease of etherification of the urea formaldehyde
condensates which contain methylol groups is also very clearly
demonstrated by the fact that, when urea is condensed with commercial
formaldehyde, which generally contains small quantities of methanol,
condensates which contain N-methylolmethyl ether groups of the formula
--NH--CH.sub.2 --OCH.sub.3
are obtained in addition to free methylol groups [H. Staudinger and K.
Wagner, Makromolekulare Chemie, Volume XII, page 173 (1954)].
According to the findings in the literature quoted above, it is also known
that the acidification of solutions of monomethylolurea or monomethylol
thiourea or the acidification of freshly prepared solutions of 1 mol of
urea and 1 mol of formaldehyde gives rise to polymethylene ureas with a
terminal methylol group which has the following composition
##STR1##
These pulverulent polycondensation products which have the character of
pigments generally contain from 6 to 12 urea groups attached by methylene
bridges. These pulverulent products can only be dissolved in special
solvents, e.g. in concentrated aqueous solutions of magnesium perchlorate,
aqueous lithium bromide solutions or solutions of lithium iodide in
methanol or acetonitrile.
Even these lower molecular weight compounds, which must be regarded as the
simplest representatives or precursors of the generally higher molecular
weight aminoplasts are resistant to swelling, are insoluble in organic
liquids and cannot be dispersed with known emulsifiers to form stable
dispersions. The higher molecular weight representatives of these
aminoplasts accordingly manifest the same insolubility and lack of
dispersability in organic liquids and dispersions thereof have not been
available.
It is therefore an object of this invention to provide novel dispersions of
aminoplasts. Another object of the invention is to provide a method for
dispersing an aminoplast in an organic medium. Still another object of the
invention is to provide a dispersed aminoplast suitable for use in the
preparation of polyurethane resins by the polyaddition process.
The foregoing objects and others are accomplished in accordance with this
invention, generally speaking, generally speaking, by providing stable
dispersions obtained by a process wherein ammonia, hydrazine or an organic
compound having a molecular weight of from about 50 to about 400 and which
contains at least two groups selected from the group consisting of
--NH.sub.2 and --NH-- with benzoquinone or a compound of the formula
R--CO--R': in which R and R' stand for the same or different radicals
selected from the group consisting of hydrogen C.sub.1 -C.sub.4 alkyl
groups which may carry chlorine substituents, C.sub.2 -C.sub.4 -alkenyl
groups, C.sub.6 -C.sub.10 aryl groups, C.sub.7 -C.sub.10 aralkyl groups,
C.sub.5 -C.sub.10 cycloalkyl groups or semi-acetals obtained by reacting
said carbonyl compounds with monohydric or dihydric aliphatic alcohols
having one to ten carbon atoms in an organic polyhydroxyl compound having
a molecular weight of from about 250 to about 14,000 as the reaction
medium. In Spite of these known properties of aminoplasts and in spite of
the already previously observed marked tendency of the N-methylol groups
temporarily formed during the polycondensation reaction to react with
alcoholic hydroxyl groups with the formation of ethers, it has now
surprisingly been found that novel finely dispersed dispersions of linear,
branched or highly branched and cross-linked aminoplasts in organic
polyhydroxyl compounds can be obtained without the hydroxyl content of
these polyhydroxyl compounds being changed if the polycondensation
reaction which gives rise to the aminoplast is carried out in the
polyhydroxyl compound itself as the reaction medium. The resulting
dispersions, which are stable indefinitely in storage, are valuable and
novel starting compounds for the production of polyurethanes by the
isocyanate polyaddition process.
This invention therefore relates to a process for the preparation of
aminoplast condensate dispersions in organic polyhydroxyl compounds which
is characterized in that the method known per se of preparing aminoplast
condensates by the oligocondensation or polycondensation of substances
which are capable of aminoplast formation is carried out in an organic
polyhydroxyl compound as the reaction medium.
Moreover, the invention provides a method of making polyurethane resins by
reacting the novel aminoplast dispersions with an organic polyisocyanate
by the isocyanate polyaddition reaction.
The process provided by the invention has the following surprising
features:
1. The functionality, e.g. of bifunctional higher molecular weight
bis-hydroxyl compounds, is fully preserved during the preparation of
finely divided aminoplast dispersions by the process of the invention.
According to past experience, one would have expected that, for example,
methylolated ureas of the following compositions (a), (b) and (c) would
easily etherify as shown in the following equations and split off water in
the process, so that the functionality of the polyhydroxyl compound would
be partly reduced or reduced to zero.
##STR2##
2. According to the invention, extremely stable finely divided aminoplast
dispersions in the polyhydroxyl compounds used as the reaction medium are
obtained.
In view of the difficulties previously encountered in the production of
stable aminoplast dispersions in organic liquids, this finding must be
regarded as extremely surprising. The dispersions which are provided by
the process of the invention are completely stable even at temperatures of
about 100.degree. C. Their use as starting components for the production
of polyurethane resins makes it possible to produce polyurethanes which
are distinguished by numerous remarkable advantages which will be
described in more detail hereinafter.
For the purposes of this invention the term aminoplasts means any
oligocondensation and polycondensation product which can be obtained in
known manner by the oligocondensation or polycondensation of any suitable
carbonyl compound, of any suitable carbonyl compound having aforesaid
formula preferably formaldehyde with any suitable nitrogen compound as
defined hereinbefore which reacts with a carbonyl compound by a process of
oligocondensation or polycondensation, preferably by way of intermediate
stages which contain N-alkylol groups such as N-methylol groups.
Aminoplasts of this kind and the condensation reactions for producing them
have already been described, for example in Houben-Weyl, Methoden der
organischen Chemie, Volume XIV, part 2 (1963), Georg Thieme-Verlag,
Stuttgart, pages 319-402, the disclosure of which is incorporated herein
by reference. The term aminoplasts in the context of this invention is
also used to include mixed condensates of nitrogen compounds and compounds
which are free from nitrogen, in particular phenols or phenol derivatives
and carbonyl compounds, in particular formaldehyde, the phenols or phenol
derivatives being optionally included in quantities of up to 60% by
weight, based on the sum of nitrogen compounds and phenols.
Suitable starting compounds for the process according to the invention also
include any nitrogen compounds which are capable of aminoplast formation,
e.g. polycarboxylic acid polyamides, urethanes and polyurethanes, ureas,
thioureas, biurets, amidines, guanidines, melamines, arylamines, ammonia,
especially in combination with quinones such as benzoquinone to form
carbonyl compounds, hydrazines, hydrazide and similar nitrogen compounds
which are capable of aminoplast formation.
The following are examples of typical representatives of nitrogen
containing compounds which are suitable for the process according to the
invention: urea, diureas, such as hexamethylene diurea, tetramethylene
diurea, ethylene diurea, acetyleneurea, dimethylacetyleneurea, oxalic acid
diamide, succinic acid diamide, adipic acid diamide, mono-hydrazides or
bis-hydrazides, hydrazodicarbonamide, carbazic acid esters,
hydrazodicarboxylic acid esters, monourethanes and particularly
diurethanes, for example, the reaction products of aliphatic,
cycloaliphatic, araliphatic and aromatic mono-chloroformic acid esters or
bis-chloroformic acid esters with ammonia and primary amines, melamine,
dicyandiamide, cyanamide, aminoguanidine, dicyandiamidine, guanamines and
guanazoles, as well as polyureas of the kind which can be obtained by
reacting aliphatic, cycloaliphatic or araliphatic diisocyanates or
triisocyanates or biuret polyisocyanates with ammonia or primary amines.
In the process according to the invention, the preparation of the
aminoplast dispersions according to the invention is carried out either by
reacting the nitrogen compounds given in the examples with carbonyl
compounds, in particular with formaldehyde or compounds which split off
formaldehyde, or the corresponding compounds which contain N-alkylol
groups, preferably N-methylol groups, are used or the corresponding
C.sub.1 -C.sub.4 alkylethers of these N-alkylol derivatives either alone
or in combination with aldehydes or ketones, in particular with
formaldehyde.
Other nitrogen compounds which can be used in addition to aforesaid
nitrogen compounds in amounts of up to 50% by weight based on the total
amount of nitrogen compounds include higher molecular weight
.alpha.,.omega.-diureas and/or their N-methylol compounds and/or
N-methylolalkylethers and/or .alpha.,.omega.-bis-alkoxymethylurethanes
which contain polyether, polythioether, polyacetal, polyester, polyester
amide or polycarbonate residues with average molecular weights of about
400 to about 10,000 between the functional groups in the .alpha. and
.omega.-positions and which may also contain urethane or substituted urea
groups. These higher molecular weight nitrogen compounds may be reacted
together with the low molecular weight nitrogen compounds already
mentioned above. The higher molecular weight nitrogen compounds capable of
aminoplast formation which are particularly advantageous for this purpose
are water-soluble or water dispersible compounds, e.g. compounds which
contain polyethylene oxide groups or residues of copolymers of ethylene
oxide with propylene oxide or tetrahydrofuran or of water-soluble
polyacetals prepared from diethylene glycol, triethylene glycol or
tetraethylene glycol and formaldehyde between the functional groups in the
.alpha. and .omega.-positions.
Although these nitrogen compounds already mentioned above which are capable
of aminoplast formation and the corresponding low molecular weight
N-methylol compounds are the preferred starting materials for carrying out
the process of the invention, it may be preferable to modify these
starting materials with other compounds, e.g. compounds which are capable
of formaldehyde condensation, because it may then be possible to control
the bond strength and physical properties of the diisocyanate polyaddition
products produced from them, such as their hardness, tendency to swell,
water retention capacity, resistance to rotting, resistance to oil and
petroleum hydrocarbons, water absorption capacity and biocidal,
bactericidal and fungicidal resistance or activity as required for their
intended use. The following are examples of such compounds which can be
easily and rapidly incorporated by mixed condensation: polyurethanes and
polyureas which contain amino end groups, polyamides of
poly-(.beta.-alanine) which have molecular weights of up to 2000,
N-methylolmethyl ethers of polycaprolactam, polythiolactams, polypeptides
of N-carboxy-.alpha.-aminocarboxylic acids, low molecular weight
polyamides of aliphatic dicarboxylic acids and diamines, polyamides and
cycloaliphatic components and aromatic components, polyamides which
contain O-- or S-- or N-- as heteroatoms, polyester amides, mixed
condensates which contain ester, urethane or urea groups in addition to
amide groups, ethoxylated and propoxylated monoamides and polyamides,
polyhydrazides and polyaminotriazoles, polysulphonamides,
phenol-formaldehyde mixed condensates with urea, melamine and
dicyandiamide, low molecular weight anilineformaldehyde condensates,
sulphonic acid amides, mononitriles and dinitriles, acrylonitrile,
urotropin, hexahydrotriazines of primary amines and formaldehyde, Schiff's
bases and ketimines or polyketimines, e.g. those obtained from 1 mol of
hexamethylenediamine and 2 mols of cyclohexanone, polyaddition products
and polycondensation products of melamine and other aminoheterocyclic
compounds with aldehydes and alcohols, polyaddition and polycondensation
products of nitriles with aldehydes, reaction products of phosphorous acid
and phosphine with carbonyl compounds. The incorporation of stilbene
compounds containing groups which tend to form N-methylol groups, and
other brightening agents, for example, those which contain an
unsubstituted sulphonamide group in their molecule, may also be
advantageous in proportions of up to 0.5% to 20% by weight. The following
should also be mentioned: 1,3,5-tri-(4'-sulphamyl-phenyl-amino)-triazine,
melamine-mono-methylene acrylamide, ureido and thioureido compounds
containing a substituted or unsubstituted vinyl group and an alkylated
methylol group (German Patent Specification No. 1,018,413),
N-cycloalkyl-N'-dialkylureas, alkylene ethers of salicylic acid amide,
benzene sulphonamide, reaction products of methoxymethylisocyanate with
mono-, di- and polyamines, carbaminyl amides according to German Patent
Specification No. 943,329, N-di-carboxylic acid mnoureides, esters of
.alpha.-oleiine-N-dicarboxylic acid monoureides according to German Patent
Specification No. 1,005,057 addition products or condensation products of
carbonyl compounds and hydrazine carboxylic acid esters,
2-hydrazino-4,6-bis-diethylamino-1,3,5-triazine,
monomethoxydihodanotriazine, ethylaminodirhodanotriazine, substituted acid
hydrazides or isopropylhydrazine and stearic acid, 2-aminothiazole,
2-aminotriazole, dichloromaleicimide, reaction products of 1 mol of
methoxymethylisocyanate and 1 mol of trimethylol-aminomethane, addition or
condensation products of N-carbonyl-sulphamic acid chloride with ammonia
or a primary amine, maleic acid hydrazide, hydrazodicarboxylic
diethylester, hydrazodicarbonamide, hydroxyethylurethane, phenyl
hydrazine, bis-biguanides, aminoguanidine, disodium ethylene
bisdithiocarbamates, phosphoric and phosphorous acid amides,
acylaminoguanidine, benzoyldicyandiamide, 1,3-disubstituted
5-amino-1,2,4-triazoles according to German Patent Specification No.
1,241,835 and maleic acid monoamides. Polyureas which can be obtained by
the action of ammonia and monoamines on isocyanatoarylesters of
phosphoric, thiophosphoric, phosphonic or thiophosphonic acids according
to German Patent Specification No. 1,129,149. Mixtures of
1,3-dimethylol-5-alkylhexahydro-1,3,5-triazone-(2) and methylolureas
according to German Patent Specification No. 1,133,386, the condensation
products of dicyandiamide and nitriles such as
2,6-diamino-4-phenyl-1,3,5-triazine (benzoguanamine),
isobutylidene-diurea, .alpha.-chloroisobutylidene-diurea,
methacrylamido-benzene sulphonic acid-(N-methanesulphonyl)-amide,
dimethylolglyoxal monoureine, dithioureas which can be obtained by
reacting ammonia or primary amines with isothiocyanates according to
German Patent Specification No. 1,241,440; isourea ether and isobiuret
ether derivatives (German Patent Specification No. 1,240,844),
cyano-substituted aliphatic ureas which an be obtained by reacting ammonia
with cyanosubstituted aliphatic isothiocyanates according to German Patent
Specification No. 1,121,606, low molecular weight mixed condensates of
melamine, urea, dicyandiamide and thiourea, methylolated
polyureidopolyamides which can be obtained according to German Patent
Specification No. 1,034,857 by reaction of .epsilon.-caprolactam with
diethylenetriamine followed by urea condensation and formaldehyde
addition. The following should also be mentioned: aminoplast resins of
dicyandiamide, formaldehyde and formic acid according to German Patent
Specification No. 1,040,236 condensation products of primary amines,
epichlorohydrin and urea, condensation products which can be obtained by
reacting sulphomethylated phenols and monomethylolurea, dimethylolurea or
trimethylolurea or methylol compounds of acid amides, ethoxylation
products of diethylene triamine, water-soluble hexamethylolmelamine
condensates and their reaction products with epichlorohydrin, low
molecular weight urea-phenol mixed condensates, N,N'-dimethylolurone,
methylene-bis-methylolurone-methylether, melamine- and ammeline-mixed
condensates. Condensation products of trimethylolphosphine oxide and
methylolmelamine, mixed condensates of melamine, formaldehyde and
polyamines such as can be prepared according to German Patent
Specification No. 1,059,659, mixed condensates which contain methylol
groups and have been obtained from 1 mol of benzoguanamine, 3 mols of
melamine and 5 mols of formaldehyde, mixed condensates of dicyandiamide
and naphthalene sulphonic acids which have been condensed with
formaldehdye, water-soluble condensation products of trimethylol and
tetramethylol melamine which may be modified with other compounds which
are capable of aminoplast formation; mixed condensates of melamine urea,
guanidine, dicyandiamide, formaldehyde and diethylmalonate, which mixed
condensates contain methylol groups; water-soluble, resinous condensation
products of 1 mol or urea and 1 or 2 mols of acrylic acid or methacrylic
acid; alkylene dimelamines which can be obtained by reacting dicyandiamide
with cyanoaminonitriles in the presence of potassium hydroxide;
condensation products of monomethylolurea, and dimethylolurea or thiourea
with glyoxal; modified carbamide methylolethers in accordance with German
Patent Specification No. 1,017,787, e.g. those obtained from urea,
melamine, butanol and methacrylic acid; reaction products of foramldehyde
condensation products of compounds of the aminotriazine or urea series
which contain free N-methylol groups with nitriles or amides or
unsaturated polymerizable or copolymerizable acids which are prepared
according to German Patent Specification No. 1,005,270; vinyl
oxyalkylmelamines which contain methylol groups; methylol compounds of
reaction products of diisocyanates with 1 mol of ethylene imine and 1 mol
of ammonia or primary amines; methacrylamide- and acrylamide-methylol
methylether; methylol compounds of N-vinyl derivatives of N,N'-alkylated
cyclic ureas such as N-vinyl-N,N'-ethylene urea; methylol compounds of
amides of phosphoric and thiophosphoric acid; methylol compounds of
biguanides; methylol-containing addition products of carbamic acid esters
and glyoxal, methylol-containing mercapto fatty acid hydrazides obtained
from methylthioglycollate and hydrazine; formamide; tertiary butyl
formamide; polyureas obtained from tetraethylenepentamine and urea;
methylol-containing quaternary ammonium derivatives of aminoacetoguanamine
according to German Patent Specification No. 1,032,259; N-methylol
compounds of biuret or N-alkylated biuret derivatives; benzene
sulphoallylamide; methanesulphoallylamide; dimethylaminosulphoallylamide;
methylol compounds of hydantoin and derivatives; methylol compounds of
salicylic acid amides, such as 5-chloro-2-oxy-benzene- 1-carboxylic
acid-n-amylamide; dichlaorophenoxyacetic acid amides;
2-amino-4-(ethylthio)-butyric acid; 2-amino-4-methoxybutyric acid;
2-amino-4-(methylsulphonyl)-butyric acid which is active against fungi,
viruses, bacteria and other parasitic organisms and which can be fixed in
the products of the process by formaldehyde condensation; methylol
compounds of low molecular weight condensation products of cyclic
lactim-O-alkylethers such as butyrolactim ether, valerolactim ether or
caprolactim ether with monoacylated hydrazines or urea, thiourea,
bishydrazides and semicarbazide.
In the process according to the invention, the above mentioned higher
molecular weight nitrogen compounds which are capable of aminoplast
formation may advantageously be used in a quantity of 0 to 40 percent by
weight, based on the quantity of low molecular weight compounds which are
capable of aminoplast formation.
Among the substances capable of aminoplast formation which are suitable for
the process according to the invention may also be included e.g.
polyfunctional N-formyl compounds or acetyl compounds, e.g. those of
hydrazine, N-methylhydrazine, N,N-dimethyl- and diethylhydrazine,
ethylenediamine, trimethylenediamine, 1,2-diaminopropylene diamine,
tetramethylenediamine, N-methyl-propylene-1,3-diamine, pentamethylene
diamine, trimethylhexamethylenediamine, hexamethylenediamine,
octamethylenediamine, undecamethylenediamine, diaminomethylcyclobutane,
1,4-diaminocyclohexane, 1,4-diamino-dicyclohexylmethane,
1-methyl-2,4-diamino-cyclohexane, 1-methyl-2,6-diamino-cyclohexane,
m-xylylenediamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane,
p-aminobenzylamine, 3-chloro-4-aminobenzylamine, hexahydrobenzidine,
2,4-dichloro-1,4-diaminobenzene, p-phenylenediamine, tolylene-2,4-diamine,
1,3,5-triisopropylphenylene 2,4-diamine,
1,3,5-trimethylphenylene-2,4-diamine,
1-methyl-3,5-diethyl-phenylene-2,4-diamine,
1-methyl-3,5-diethylphenylene-2,4-diamine, 4,4'-diaminodiphenylmethane and
4,4-diaminodiphenylether.
The formylated polyamines mentioned above are valuable compounds capable of
aminoplast formation even in the nonacylated state, i.e. as free
polyamines, since in this form they can be reacted in particular with
formaldehyde to form highly cross-linked polyhexahydrotriazine
dispersions.
In preparing the dispersions according to the invention it has been found
particularly valuable to add 0.5% to 30% by weight, based on the total
quantity of aminoplast forming starting compounds, of chain breaking
agents, that means, substances which terminate the molecular chain which
have not hitherto been known, in particular lactams such as
.epsilon.-caprolactam, valerolactam, butyrolactam and the corresponding
thiolactams. However, other monofunctional compounds may also be used for
chain breaking reactions to control the viscosity properties of the
dispersions, for example formamide or acetamide.
The preferred chain breaking agent used is .epsilon.-caprolactam. When
preparing polymethyleneureas, for example, it is possible with the aid of
.epsilon.-caprolactam to obtain polymer homologous series of
polycondensates which are linked by methylene groups and have terminal
lactam units. These polycondensates correspond to the following formula
##STR3##
in which X=4 to 20.
For requiring the chain length, e.g. in the case of polymethyleneurea,
polymethylenethiourea and polymethylene melamine dispersions, which are
the ones preferably prepared according to the invention, as well as the
corresponding dispersions which are cross-linked with excess formaldehyde,
it may also be advantageous to use 0.5% to 30% by weight, based on the
quantity of solids in the dispersion, of the following compounds as chain
breaking agents: 2,4-dichlorophenoxyacetic acid amides, e.g. the
N-methylamide, N-ethylamide, or N-butylamide;
2-methyl-4-chlorophenoxyacetic acid and its amide and N-substituted
amides; 4-(2,4-dichlorophenoxy)-butyric acid, trichloroacetic acid amide;
2,2-dichloropropionic acid; 2,2-dichloropropionic acid amide; the
N-methylol compounds of 2,2-dichloropropionic acid amide; the
N-methylolmethylether of 2,2-dichloropropionic acid amide, chloroacetic
acid diallylamide; urethanes such as N-(3-chlorophenyl)-carbamic acid
isopropyl ester; N-(4-chlorophenyl)-N,N'-dimethylurea; and urethanes
obtained by reacting aromatic isocyanates which may contain several
chlorine atoms with isopropanol or by reacting methyl isocyanate with
isopropanol. The incorporation of halogenated triazines such as
2-chloro-4,6-bis-ethylamino-s-triazine and of formyl compounds of
aminoguanidine is also suitable; also imidazoles, 2-methylimidazole,
benzimidazole and mercaptobenzimidazoles; the following should also be
mentioned: 3-amino-triazole, N-cyclohexyl-N'N'-dimethylurea, disodium
ethylene-bis-dithiocarbamate, 5-chloro-2-hydroxybenzene-1-carboxylic acid
n-amylamide, the methylol compound of
5-chloro-2-hydroxybenzene-1-carboxylic acid amide, and N-methylol
compounds which can be obtained by reacting the chloroformic acid ester of
hexachloroisopropanol with ammonia and subsequently with formaldehyde.
Any compounds which contain only one of the groups which take part in the
condensation reaction leading to aminoplast formation are in principle
suitable for use as chain breaking agents. Adjustment of the viscosity of
the products of the process can easily be controlled by using these chain
breaking agents mixed with the higher functional nitrogen compounds.
In a particular embodiment of the process according to the invention,
compounds which, in addition to containing groups which are capable of
aminoplast formation, also contain groups (e.g. chromophoric groups) which
impart the properties of dyes and/or brightening agents to these starting
materials are included in quantities of 0.5% to 20% by weight, preferably
2% to 14% by weight, based on the total quantity of aminoplast forming
starting compounds. By incorporating these compounds, it becomes possible
to produce colored dispersions with extremely stable colors, and these
color properties are carried over into the polyurethane resins which are
produced from these dispersions.
Brightening agents of the following composition are examples of such
compounds:
##STR4##
as well as numerous dyes which have fluorescent properties such as those
mentioned in Examples 10 and 13.
In the process of aminoplast formation according to the invention, the
starting materials mentioned above, insofar as they do not yet contain a
sufficient number of reactive alkylol and/or alkylol ether groups for the
polycondensation reaction, are first reacted with carbonyl compounds, i.e.
in particular aldehydes or ketones such as formaldehyde, acetaldehyde,
butyraldehyde, cyclohexane aldehyde, benzaldehyde, salicylic aldehydes,
4-methylbenzaldehyde, terephthalic dialdehyde, acetone, diethylketone,
cyclohexanone or benzophenone or also quinones such as benzoquinone as
reactants for ammonia.
The reactant used in the process according to the invention for the
reaction with the above mentioned starting compounds which preferably
contain nitrogen is preferably formaldehyde in the form of an aqueous
solution or in the gaseous form of any compounds which split off
formaldehyde or react like formaldehyde such as its semiacetals with
monofunctional or polyfunctional alcohols such as methanol, ethanol,
butanol, ethylene glycol, or diethylene glycol, etc.; or acetaldehyde,
chloral, acetone, methyl ethyl ketone, methyl isobutyl ketone or
cyclohexanone. Aqueous formaldehyde is particularly preferred.
In addition to the above mentioned compounds which are preferred for
aminoplast formation, substances which are capable of so-called phenoplast
formation may also be added, as explained above, in quantities of 0.5% to
50% by weight, preferably 5% to 40% by weight, based on the total quantity
of aminoplast forming starting compounds, for the purpose of modifying the
dispersions according to the invention. These modifying compounds do not
reduce the condensation velocity. They are capable of substantially
modifying the aminoplast dispersions and enable the viscosity properties
of the dispersions according to the invention to be controlled. Among the
compounds which are capable of phenoplast formation, the following are
preferred: phenol, bisphenol, resols of phenol or bisphenol and
formaldehyde, condensation products of phenol and cyclohexanone,
phenolsulphonic acids, naphthalene sulphonic acids and the like.
When carrying out the process according to the invention, aminoplast
formation may be activated if desired with the aid of any known
condensation catalysts, e.g. formic acid, hydrochloric acid, sulphuric
acid, phosphoric acid, acetic acid, thioacetic acid or maleic acid and, of
course, also bases such as sodium hydroxide, potassium hydroxide, calcium
hydroxide, barium hydroxide, zinc oxide, magnesium oxide, phosphoric acid,
phosphates, primary and secondary potassium hydrogen phosphate, ammonium
sulphate, numerous organic acid anhydrides, and the like, compounds which
split off acids, such as ammonium chloride, trimethylammonium formate,
chloral hydrate, amine salt of formic acid and other organic carboxylic
acids, maleic acid semiesters, tertiary amine salts, etc., dibenzoyl
peroxide, carbonic acid, N-carbamic acids, glycol chlorohydrin, glycerol
chlorohydrin, epichlorohydrin and various copper, zinc, divalent tin,
cadmium and magnesium salts of organic acids. Various metal oxides or
their hydrates may also be used.
The activators preferably used in the process according to the invention
are hydrochloric acid, sulphuric acid, phosphoric acid, formic acid,
maleic acid, sodium hydroxide, potassium hydroxide, barium hydroxide,
benzyldimethylamine and triethylamine.
The activators are generally used in quantities of from 0.05 percent to 5
percent by weight, preferably 0.1 percent to 2 percent by weight, based on
the total quantity of all reactants taking part in the polycondensation.
The process according to the invention may be carried out in any suitable
organic polyhydroxyl compound as the reaction medium. Suitable
polyhydroxyl compounds for the process according to the invention are in
particular the higher molecular weight polyhydroxyl compounds known in
polyurethane chemistry to react with an organic polyisocyanate to form a
polyurethane resin and having a molecular weight of about 250 to about
14,000, preferably about 400 to about 6000. These may if desired, be used
as mixtures with low molecular weight polyhydroxyl compounds which have
molecular weights of about 62 to about 250. These low molecular weight
polyhydroxyl compounds may be included in quantities of from about 5% to
about 50% by weight.
Suitable higher molecular weight polyhydroxyl compounds are in particular
hydroxyl polyalkylene ethers which contain at least two terminal hydroxyl
groups and in which preferably at least 10% of the hydroxyl groups are
primary hydroxyl groups. Polyethers of this kind can be prepared in known
manner by reacting suitable starter molecules with alkylene oxides such as
ethylene oxide alone, or propylene oxide, butylene oxide, styrene oxide or
epichlorohydrin or mixtures of these compounds first and then with
ethylene oxide to provide terminal primary hydroxyl groups.
Any suitable initiator may be used in making the polyethers such as, water,
ethylene glycol, diethylene glycol, polyethylene glycol, propane-1,2-diol,
propane-1,3-diol, butane-1,4-diol, hexane-1,6-diol, glycerol,
hexane-1,3,6-triol, trimethylolpropane, aliphatic or aromatic polyamines,
e.g. ammonia, methylamine, ethylene diamine, tetramethylene diamine or
hexamethylene diamine, diethyl | | |
