Brief Description Of The Invention A water-based composition containing a water soluble linear aminoplast-ether copolymer containing aminoplast segments interlinked through ether segments. Background To The Invention Aminoplasts are defined herein and in the claims as an A-stage class of thermosetting resin based on the reaction of an amine with an aldehyde and the related acetals containing amines or amides. The most commer¬ cially used aldehyde is formaldehyde, and the most im¬ portant amines are urea and melamine. They are used in molding, adhesives, laminating, textile finishes, per¬ manent-press fabrics, wash-and-wear apparel fabrics, protective coatings, paper manufacture, leather treat¬ ment, binders for fabrics, foundry sands, graphite re¬ sistors, plaster-of-paris fortification, foam struc- tures, and ion-exchange resins. A significant struc¬ tural component of an aminoplast resin is the amino group to which is bonded at least one alkylol or alky- lol ether or ester functional group. Those functional groups enter into condensation (heterolytic) reactions and provide the leaving groups for the reaction. The aminoplast typically provides at least two of such amino groups per molecule and one or two functional groups per amino group. The condensation reaction can generate a low to moderate molecular weight polymer (as would occur in making a B-stage resin) , a highly crosslinked polymer (as would occur in making a thermo- set C-stage resin) by homopolymerization or copolymeri- zation, or it can generate a modification of the resin that either provides other type functionality or elimi- nates such functionality from the resin. For example,

a starting monomer that contains the amino group with an associated methylol or methylol ether or ester group can be partially condensed and modified with a monomer that possesses, in addition, different functionality (such as ethylenic unsaturation) and such partial modi¬ fication allows the aminoplast to be dimerized, oli- gomerized or polymerized by a homolytic reaction through such different functionality to form a ino- plasts with a plethora of methylol and/or methylol ether and/or ester groups. This same result can be achieved by different route, by having the skeleton of the aminoplast possess other functional groups that can enter into heterolytic or homolytic reactions. For ex¬ ample, methacrylamide can be reacted with formaldehyde to form an aminoplast, and through the unsaturation, polymerization can be effected to create a linear poly¬ mer with pendant methylol or methylol ether or ester functional groups. Illustrative of such aminoplasts are the following:

Figure 1. Partial list of aminoplasts

wherein R is hydrogen, alkyl containing 1 to about 4 carbon atoms, and acyl containing 1 to about 4 carbon atoms; RO is alkyl of from 1 to about 4 carbon atoms, aryl, cycloalkyl, and the like; Rl is alkyl of from 1 to about 4 carbon atoms; and x is 0 or 1, and y is at least 2.

The RO- functionality of such aminoplasts provide the leaving groups of the alkylol (e.g., methylol) or alkylol ether or ester (e.g., methylol ether or ester) functional groups. Alkylol (e.g., methylol), alkylol ether (e.g., methylol ether) or alkylol ester (e.g., methylol ester) groups can condense with themselves to form ROH volatile compounds or water. They can condense with complementary functional groups, such as compounds containing active hydrogen groups, e.g., primary and secondary amines, carboxylic acids, alcohols, phenols, mercaptans, carboxamides (including amides from urea, thiourea) , and the like.

Most aminoplasts contain a minor amount of dimer and oligomer products. These products are formed in the making of the aminoplast and represent precondensation between aminoplast monomers. The dimer and oligomer products contain substantially more -OR functionality than the aminoplast monomer. As noted above, aminoplasts are used to form thermo- set resin structures. Because they contain at least two RO- functional groups, they are used to react in systems that contain at least two complementary func¬ tional groups. Frequently, aminoplasts are added to resin formulations as one of many components. In such embodiments, there are no perceptible step-wise reac¬ tions between the aminoplast and any other component of the formulation. In such situations, it is not feasi¬ ble to determine with any degree of accuracy as to

which of the specific components of the formulation the aminoplast reacts.

The term "associative thickener" is art recognized to mean a nonionic hydrophobically modified water- soluble polymer capable of interacting in aqueous solu¬ tion with itself and with other species such as latex particles. Typically they are made by polymerizing polyethylene oxide prepolymers with isocyanates. Mono- ols or diols with large aryl, alkyl, or aryl/alkyl groups are included to provide the hydrophobic modifi¬ cation. They are described in a number of patents. Hoy et al. , U.S. Patent No. 4,426,485, patented January 17, 1984, broadly describes these materials as "a wa¬ ter-soluble, thermoplastic, organic polymer ... having segments of bunched monovalent hydrophobic groups." This patent, in its "Description of the Prior Art," discusses a major segment of the prior art, and without endorsing the conclusions therein stated, reference is made to such description to offer a background to this invention.

The two Emmons et al. patents, U.S. 4,079,028 and U.S. 4,155,892, patented March 14, 1978 and May 22, 1979, respectively, describe polyurethane associative thickeners that contain hydrophobic groups intercon- nected by hydrophilic polyether groups. The thickeners are nonionic.

There are a number of commercial associative thick¬ eners based on the descriptions of the Hoy et al. and Emmons et al. patents. Background on the use of thickeners in waterborne polymer systems, including those embraced in the char¬ acterization of this invention is set forth in the ex¬ tensive literature on the subject, such as U.S. Pat. Nos. 4,426,485, 4,155,892, 4,079,028; 3,035,004; 2,795,564; 2,875,166 and 3,037,952, for example. The

polymeric thickeners of this invention are also suit¬ able as substitutes for the polymeric thickeners in the polymeric systems disclosed in U.S. Pat. Nos. 2,875,166 and 3,035,004 and in Canadian Pat. No. 623,617.

For the purposes of this invention and the discus¬ sion of the prior art, the skeletal unit of the amino¬ plast is the structure of the aminoplast minus the RO- leaving groups bonded to alkylene of the alkylol or al- kylol ether or ester of the aminoplast, regardless of whether any of the RO- groups are removed from the aminoplast. That skeletal unit is referred to herein and in the claims as "Amp."

In the following description and in the claims hereof, the term "water dispersible, " as such relates to aminoplast containing compositions and precursors to such compositions, that are water soluble or mechani¬ cally dispersible in water in a stable particulate form. A stable particulate form is one that retains its chemical characteristics after an extended period of time. It can be mechanically mixed in such particu¬ late form in water, for an extended period of time at normal ambient conditions.

The term "linear," when used herein and in the claims to characterize a polymer, relates to a polymer that is devoid of crosslinking or branching that ren¬ ders the polymer solid and cured. A "wholly linear" polymer is a polymer that is devoid of crosslinking and branching. A linear polymer may or may not be a wholly linear polymer.

The symbols and designations used herein are in¬ tended to be consistently applied, especially as used in formulations and equations, unless specifically stated otherwise.

The Invention

This invention relates to novel water-based composi¬ tions. The compositions are thickened and/or provided with wetting characteristics by the inclusion in the composition of an aminoplast-ether copolymer formed by a process that does not rely on an urethane-forming po¬ lymerization reaction in order to generate the copoly¬ mer' s backbone structure.

This invention relates to a novel water-based co po- sition because of the presence in the composition of a linear aminoplast-ether copolymer of the formula:

where the divalent ROl contains a divalent alkyleneoxy containing moiety, Amp is the skeletal residue of an aminoplast, as stated above, R is defined above, p is a positive number that is equal to the free valence of Amp minus 2, RO is bonded to alkylene units of Amp, and a is a number greater than 1, preferably greater than 2. Amp includes any dimer and oligomer component of the aminoplast. In a much preferred embodiment of the invention, ROl is derived from a water dispersible al¬ kylene polyether, preferably a water soluble alkylene polyether, and the novel linear aminoplast copolymer of the invention is water dispersible, and preferably, wa¬ ter soluble. In addition, the invention relates to a novel water- based composition that contains a linear aminoplast- ether copolymer possessing one or more pendant groups, preferably hydrophobic pendant groups. Such a copoly¬ mer contains a unit of the formula:

wherein

R02 is a hydrophobic group, different from RO-, that is covalently bonded to Amp through a heteroatom and contains at least two carbon atoms, prefera¬ bly at least two sequential carbon atoms, p2 is number that is equal to the free valence of Amp minus (2 + q) , and q is a positive number. The copolymer preferably con-

<?/ tains a ratio of « that is at least about 0.01.

In another embodiment of the invention, the linear aminoplast-ether copolymer provided in the water-based composition possesses end groups characterized by a component of the units making up the copolymer, or a monofunctional group that effectively end-caps the co¬ polymer, forming the end group. This yields a copoly¬ mer of the formula:

wherein each ROO is the same or different terminal group, such as hydrogen, -R01-H, Amp bonded -(OR)pi, - Amp- (OR) pi, or any other monofunctional organic groups, such as alkyl, cycloalkyl, aryl, alkaryl, aralkyl, al- kyoxyalkyl, aroxyalkyl, cycloalkoxyalkyl, and the like, and pi is a positive number that is equal to the free valence of Amp minus 1. In addition, the invention en¬ compasses a copolymer of the formula:

where each ROOl is the same or different, and is ROO or R02.

A particularly preferred linear aminoplast-ether co¬ polymer comprises units of the formula:

wherein ROl and R are described above, n has a value of at least 2, x is 0 or 1, s is (3 + x) - 2, and the av¬ erage value of x in the copolymer is about 0 to about 0.05. Another preferred composition of the invention is a novel linear aminoplast-ether copolymer having the formula:

where s + t equals (i) the free valence of the

moiety and (ii) 4 - x; and the average value of t ± _s about 0.01 to about 0.5.

In a further preferred embodiment of the invention, the novel linear aminoplast-ether copolymer of the in¬ vention comprises a copolymer that possesses end groups as illustrated by the following structure:

wherein each R002 is the same of different terminal group, such as hydrogen, -R01-H, -(OR)pi, -AmpO- (OR) pi, or any other monofunctional organic groups, such as al¬ kyl, cycloalkyl, aryl, alkaryl, aralkyl, alkyoxyalkyl, aroxyalkyl, cycloalkoxyalkyl, and the like, and pi is a positive number that is equal to the free valence of AmpO minus 1. AmpO is depicted in formula V. In a pre¬ ferred embodiment of the invention, the linear amino¬ plast-ether copolymer comprises a copolymer that pos¬ sesses end groups affecting the performance of the co¬ polymer. Such embodiment is illustrated by the follow¬ ing structure:

wherein each R003 is the same of different terminal group, such as hydrogen, -R01-H, -(OR)pi, -AmpO- (OR) pi, -OR02 or any other monofunctional organic groups, such

as alkyl, cycloalkyl, aryl, alkaryl, aralkyl, al- kyoxyalkyl, aroxyalkyl, cycloalkoxyalkyl, and the like, and pi is a positive number that is equal to the free valence of AmpO minus 1. AmpO has the same meaning as Amp.

In the foregoing characterizations set forth in for¬ mulae I, la, II, Ila, III, Ilia, IV, and IVa, each -OR and -OR02 group is directly bonded to Amp through a hy- drocarbyl moiety bonded to nitrogen therein.

This invention relates to aqueous systems that con¬ tain any one or more of the above defined compositions. The invention relates to a thickened water containing composition in which water is present in a major amount and one or more of the aminoplast-based compositions of formulae I, la, II and Ila in a minor amount. Particu¬ larly preferred are such thickened water containing systems wherein the aminoplast-based compositions are the aminoplast-based compositions of formulae III, Ilia, IV and IVa. Particularly preferred water-based systems are coating, adhesive, quenchant, flocculant, cosmetic, ink, textile printing, paste, personal care product, cosmetics, hydraulic fluid, and the like, com¬ positions.

In addition, the invention relates to a water-based composition that contains a major amount of water, mi¬ nor amount of an associative thickener of the formula:

wherein R03 is a monovalent hydrophobe as illustrated in the definition of R02, and v has an average value of about 2 to about 10,000, and an amount of a "dispersed polymer" that is greater than the amount of the asso-

ciative thickener, which dispersed polymer provides the basic utility for the composition. In this sense, the dispersed polymer is typically solvent dispersible, i.e., it has the capacity of being dissolved by a sol- vent, and on drying the composition, i.e., removing wa¬ ter and solvent present, the dispersed polymer is cur¬ able to either a solid thermoset structure or a solid thermoplastic.

Detailed Description Of The Invention The linear aminoplast-ether copolymers of formula I et seq. are made by the novel condensation reaction of a polyfunctional aminoplast with a difunctional poly¬ ether (alone or with another polyol, as characterized with respect to formulae XII and XIII) in the presence of an acid catalyst. In the prior art, as noted above, aminoplasts are condensed with polyfunctional compounds to produce thermosetting resins or thermoset products (i.e., C-stage resin) . The reaction of this invention produces a linear copolymer. Thus, the copolymers of formulae I, II, III, IV, and V are either liquid or thermoplastic solids that are solvent soluble and water dispersible.

The linear aminoplast-ether copolymer are made by the copolymerization reaction of a polyfunctional amin- oplast with an ether containing two active hydrogen terminal groups, in the presence of an acid catalyst, especially a Bronsted-Lowery acid provided in catalyti- cally effective amounts. The reaction is continued un¬ til the desired molecular weight is achieved. The de- sired molecular weight of the copolymer is dependent on the intended use of the copolymer. The molecular weight of the copolymer may range from about 12,000 to about 300,000, preferably from about 20,000 to about 100,000, and most preferably from about 30,000 to about

80,000. The aminoplast is a polymerizable resin of the general formula: c- . -Amp

'z VII. wherein z is a positive number having a value of at least 2. The ether containing two active hydrogen ter- minal groups comprises a wide variety of compositions. A preferred class of them is nonionic. Illustrative of a preferred class of such ethers are polyalkylene ox¬ ides of the formula:

H- Alkylene Oxide -H VIII. where "alkylene oxide" is a divalent moiety containing at least two alkylene oxide units in which

1. the alkylene oxide units form a linear chain and provide a terminal OH, or

2. the alkylene oxide are bonded to a starter mole¬ cule, such as a diamine, urea, carbamate, phenoxy, amide, bis-imide, and the like, and providing a terminal OH, and/or

3. in which alkylene oxide are bonded to a terminal group that possesses a moiety that provides the active hydrogen (-H in formula VIII) . Further illustrative of such a preferred class are the water dispersible polyether compounds of the formula:

HxlX-(R04)x4 (R05)x5(R06)x6(R07)x7 (R08)x8 -XHx2 IX, wherein

X is an active hydrogen-attached functional moiety such as oxy (-0-) , sulfidyl (-S-) , amino ( " ) , carboxy (-COO-) , carboxamido, silyl, phosphoryl, ureido, and the like; R04 and R08 are alkyl of 2 to about 8 carbon atoms; R05 and R07 are one or more alkylene oxide units, e.g., such as water dispersible ethylene oxide,

butylene oxide, mixed ethylene oxide/1, 4-butylene oxide, and the like;

R06 is a divalent group such as alkyleneoxy, alkyle- nepolyamine, cycloalkylene polyamine, phenoxy, uriedo, carbamate, amide, and the like; xl and x2 are each equal to the free valence of X; x3, x4, x5, xδ and x7 are each 0 or 1, and one or more of x4 and x6 is 1. Specific illustrations of a limited class of polyethers encompassed by formula IX are the Carbowax® and Pluronic® polyether diols sold by Union Carbide Chemi- cals & Plastics, Inc. and BASF Wyandotte, respectively. There are a variety of functional fluids based on al¬ kylene oxides that are sold by Union Carbide Chemicals & Plastics, Inc. and BASF Wyandotte that are encom¬ passed by formula IX. The molecular weight of the polyether reagent may range from about 106 and lower, to about 35,000, and higher.

In the prior art, as noted above, aminoplasts are condensed with polyfunctional compounds to produce thermosetting resins or thermoset products (i.e., C- stage resin) . The above method produces a linear co¬ polymer. Thus, the copolymers of formulae I, II, III, IV, and V are either liquid or thermoplastic solids that are solvent soluble and water dispersible.

Aminoplast reagents include, but are not restricted to, aldehyde reaction products of melamines, ureas, benzoguanamines, glycolurils, and the like, to produce the array of aminoplasts, including but not limited to those described in Figure 1 above. While any of these can be used to make associative thickeners, the gly- colurils, such as those of formula X

where R and x are defined above, have shown appropriate hydrolytic stability, when reacted with the polyether compounds, such as those encompassed by formula IX, to meet commercial criteria ^' for associative thickener- containing coating compositions. However, the reaction products of such aminoplasts with, e.g., thiols and NH groups from amides and carbamates, encompassed by for¬ mula IX, are much more hydrolytically stable than amin¬ oplast ether linkages. The use of such reactants allow for the production of most hydrolytically stable amino¬ plast-based copolymers.

Suitable polyethers include such diverse polyal- kylene polyethers as those having the formula:

Figure 2. Partial list of polyalkylene polyethers where xlO has a value of from about 1 to about 400, R12 are alkyl of 1 to about 4 carbon atoms or acyl of 1 to

about 3 carbon atoms. The preferred polyethers are wa¬ ter soluble. The most preferred polyethers are the al¬ kylene polyethers where the predominant alkylene groups are ethylene. The most desirable polyethers are poly¬ ethylene oxide diols that possess molecular weights from about 1,000 to about 20,000.

Illustrative of the desirable polyethylene oxide diols are those of the formula:

HO-(-CH ₂ CH ₂ O) _x11 CH ₂ CH ₂ OH xi. wherein xll has a value of about 20 to about 500, pref¬ erably from about 50 to about 350, and most preferably from about 100 to about 250.

A further desirable embodiment of the invention is the modification of the linear aminoplast-ether copoly¬ mers used in making the coatings of the invention by including a minor mole proportion of the following unit structure in the repeating structure of the copolymer: wherein R15 is the residue of a diol possessing greater hydrophobicity than ROl, thereby providing for a linear copolymer containing the structure —

-[-Amp — R, 01 - "Amp- 15 XIII

X29 x30 wherein x29 has a value that is greater than x30.

Preferably, is less than about 1, preferably less than about 0.33. Illustrative of such R15 groups are —

wherein x31 has a value of about 8 to about 20, x32 has a value of about 8 to about 23, x33 and x34 have values of 0 to about 8. The linear copolymer of formula XIII

may be modified to possess the terminal groups of for¬ mulae la, Ila, Ilia, and IVa, discussed above.

The linear aminoplast-ether copolymers embraced by formulae I and XIII, may contain, as well, hydrophobe pendant groups. This is illustrated by the presence of significant hydrophobic groups extending from amino¬ plast component of the linear backbone of the amino¬ plast-ether copolymer. Such hydrophobe groups are typi¬ cally bonded to the backbone through ether or ester groups, as illustrated in formula VI. The nature of the hydrophobe can enhance the performance of the re¬ sulting aminoplast-ether copolymer as an associative thickener in water-based coating compositions. Aro¬ matic groups, e.g., phenyl, biphenyl, anthracyl, and the like, present in the hydrophobes are better than hydrophobes based on wholly aliphatic containing groups, especially for high shear viscosity attributes when used in water, and especially so with respect to the use of the associative thickeners in latex paints. Suitable hydrophobe groups are derived from alcohols, thiols, carboxylic acids, carboxamides, and carbamates of the formula:

wherein R09 is hydrogen, alkyl of 8 to about 24 carbon atoms, alkenyl of 8 to about 24 carbon atoms and al- kynyl of 8 to about 24 carbon atoms, RIO is mono, di and tri(aryl), Rll is aryl, mono, di and tri (alkaryl) , mono, di and tri (alkcycloalkyl) , alkenyl and alkynyl where the alkyl, alkenyl and alkynyl contain 1 to about 24 carbon atoms and the cycloalkyl contains about 4 to about 8 carbon atoms, R12 is one or more alkylene ox¬ ide, Y is an active hydrogen containing group such as OH, SH, COOH, CONHR08, NR09COOH, xl3, xl4, xl5 and xl6 are 0 or 1, and two or more of xl3, xl4, xl5 and xl6

have the value of 1 at the same time. Illustrative of such hydrophobe groups are the following precursor com¬ pounds from which the hydrophobe is derived:

CH ₃ (CH ₂ ) _x17 SH R ₁₅ CNH(CH ₂ ) ₅ OH

CH ₃ (CH ₂ ) _χ17 0(CH ₂ CH ₂ 0) _χ1 ,

CH.(CH ₂ ) _x17 _NH(CH ₂ CH ₂ 0)

where the derived hydrophobe are —

and in which RIO is aryl, or alkyl of 8 to 24 carbon atoms, xl5 has a value of 7 to 23, xl6 has a value of 1

to about 20, xl9 has a value of 0 to about 120, x26 has a value of about 8 to about 60, xl7 has a value of about 7 about 23, xl8 has a value of 1 to about 23, x20 is 0 or 1, x21 is 0 or 1, the sum of x20 and x21 is 1 or 2, x22 is 1 to about 20, x23 is 1 to about 20, x27 is 0 or 1, x24 has a value of about 8 to 23, and x25 has a value of about 8 to 20. Another class of such hydrophobes are based on partially saponified fatty acid glycerides such as partially saponified linseed oil, tall oil, cottonseed oil, caster oil, coconut oil, corn oil, oiticica oil, perilla oil, poppyseed oil, rapeseed oil, and the like. A further class of such hydrophobes are ethoxylates of such partially saponi¬ fied fatty acid glycerides. Illustrative of such es- ters are —

where R16 are the hydrocarbyl portion of the natural fatty acid component of the fatty acid glycerides Their ethoxylates are illustrated as —

where x28 has a value of 1 to about 200, and R16 are the natural fatty acid component of the natural oil.

The choice of hydrophobe is primarily dependent on the use ascribed for the associative thickener of the invention. For example, the copolymer without the hy-

drophobe provides wetting agent and viscosity control features in water and with water-based compositions. In the demanding area of water-based coatings, it is desirable to include a hydrophobe as a component of the aminoplast-ether copolymer of the invention. Any of the aforementioned hydrophobes will affect the viscos¬ ity of a latex paint giving rise to benefits to the paint. However, certain of the hydrophobes in combina¬ tion with certain of the aminoplast-ether copolymers, provide associative thickeners that essentially satisfy the most demanding commercial standards. For example, the use of dodecylphenol ethoxylates as the hydrophobe achieves particularly desirable high shear viscosity characteristics, resistance to spatter and gloss reten- tion in semi-gloss paints when compared to nonylphenol and octylphenol ethoxylates which have often been em¬ ployed in making associative thickeners with urethane in the polymer backbone. It has also been observed that using tristyrylphenol ethoxylates improves the gloss of semi-gloss paints even further and provides better high shear resistance according to the ICI cone and plate viscometer reading in flat latex paints. Re¬ acting Bisphenol A into the associative thickeners (to form the copolymer of formula XIII) reduces the synere- sis common when using associative thickeners in concert with cellulosics.

This invention relates to the use of any aminoplast, including those specifically recited in Figure 1 above, to make the copolymer of the invention. Of these amin- oplasts, exceptional performing associative thickeners are obtained from the reaction of glycolurils with al¬ kylene oxide glycols to which are incorporated hydro¬ phobic pendant moieties.

The production of the aminoplast-ether copolymers are made by solvent or melt polymerization. The

typical preparation of an aminoplast-, such as glycolu- ril-, based associative thickener involves dissolving the aminoplast (e.g., glycoluril) , a polyether com¬ pounds within the scope of formula IX (such as a Carbo- wax® polyether sold by Union Carbide Chemical and Plas¬ tics, Inc., Danbury, CT. ) , with or without the addition of a more hydrophobic polyol within the scope of for¬ mula XII, and an ethoxylated hydrophobe, in a stripping solvent, such as alkylated benzene (e.g., toluene or xylenes) . Prior to the combination of these reagent, each may be dried by azeotropic distillation with tolu¬ ene, xylenes, or a mixture of them, or by any other drying procedure. Total concentration of the reagents in the solvent may be maintained from about 10 to about 60 weight %. The temperature of the mixture may be brought to about 60-140°C, preferably to about 80- 120°C. An acid catalyst, such as a sulfonic acid cata¬ lyst, is then added. The reaction mixture is placed under reduced pressure to bring about a steady distil- lation of the toluene/xylenes which azeotropes the al¬ cohol byproduct that must be removed in order for the reaction to proceed. Fresh solvent is constantly added to maintain a constant level. The reaction is allowed to proceed until a given high viscosity is achieved as measured by Gardner bubble tubes or until viscosity in¬ crease ceases. Such viscosity increase indicates an increase in the molecular weight of the copolymer. Specific illustration of solvent process

1. Polyether polyol, hydrophobe and azeotroping solvent (e.g., toluene) are added to an appropriately sized container that accommodates a heater, temperature reading device, a nitrogen inlet, and a Dean Stark water trap and condenser.

2. The mixture of step 1 is heated to reflux to dry the mixture by azeotropic distillation. When water re¬ moval ceases, the mixture is cooled to about 100°C, and the water trap is removed. A distillation column and receiving vessel are installed in the container.

3. Glycoluril (e.g., Powderlink 1174) is added and al¬ lowed to melt.

4. The catalyst is added and vacuum is applied. The pressure is reduced to a level that causes a steady distillation of solvent at about 100°C. The solvent is continually replenished from a pressure equalizing add funnel.

5. As the reaction proceeds, samples are removed and cooled to room temperature, and the Gardner bubble viscosity is measured.

6. When the proper viscosity is reached, the heat is re¬ moved and the mixture is cooled in a water bath. When the temperature has been reduced to below 75°C, an amine neutralizing agent is added. When the tem- perature is reduced to below 65°C, the polymer solu¬ tion is poured out onto trays to air dry.

7. The dried polymer is cut into strips and redissolved in water or water/cosolvent mixture.

Polymerization in the melt involves the admixture of the same reagents in the absence of a solvent with a heavy duty laboratory mixer (such as an Universal Sigma Blade Mixer, sold by Baker Perkins Guittard SA, Paris, France) at a temperature sufficient to generate leaving groups and remove the reaction condensation products. The ventilation of the reaction is necessary in order to shift the reaction to the right and prevent an equi¬ librium reaction from occurring that impedes the reac-

tion before the desired degree of polymerization is achieved.

Catalysts useable for effecting the copolymerization reaction includes the standard Brδnsted-Lowery acid catalysts typically used for the condensation of amino¬ plast resins. Such acid catalysts include mineral ac¬ ids (e.g., HCl, H2S03, H2P04, and the like), aryl sul¬ fonic and alkylated aryl sulfonic acids, such as ben¬ zene sulfonic acid, p-toluene sulfonic acid, 1- naphthalene sulfonic acid, 2-naphthalene sulfonic acid, naphthalene-1, 5-disulfonic acid, naphthalene-2, 7- disulfonic acid, 1,3, 6-naphthalene trisulfonic acid, naphtholsulfonic acid, dinonylnaphthalene disulfonic acid, dodecylbenzene sulfonic acid, oxalic acid, maleic acid, hexamic acid, alkyl phosphate ester, phthalic acid, and copolymerized acrylic acid. Of these cata¬ lysts, the sulfonic acid catalysts are the most effec¬ tive and efficient for making the copolymers of the in¬ vention and dodecylbenzene sulfonic acid is the most preferred sulfonic acid catalyst.

Glycolurils are marketed by Cytec Industries as Cy- mel 1170, 1171, 1175 and Powderlink 1174. The Cymel versions are either mixed methylolated species and typically contain a relatively high isomer content of up to about 20 weight percent. Powderlink 1174 is a purer form that is solely the methyl ester of the for¬ mula:

with about 3-5 weight percent of a dimer-oligomer of the monomer form. The purer the monomeric form of the aminoplast, the better it is in forming the copolymers

of the invention. In about 5-7 weight percent of Pow¬ derlink 1174, x is 0, and such monomer form is trifunc- tional. The dimer-oligomer forms provide greater amounts of methoxy per molecule. For example, the di- mer contains 6 methoxy functional groups. Such tri- and hexa-functionality does not alter this invention. The glycoluril ether linkage is much more resistant to hydrolysis than other aminoplast ether bonds. The higher dimer-oligomer content of the less pure glycolu- rils is not as favored as the lower dimer-oligomer con¬ tent of Powderlink 1174.1

The ratio of aminoplast resin to the difunctional polyether is not narrowly critical. Typically, either the aminoplast resin or the difunctional polyether may be used in molar excess or stoichiometrically equiva¬ lent amounts in making the linear copolymer of the in¬ vention. In characterizing stoichiometry of the amino¬ plast resin, the resin is treated as being difunctional since linearity, according to the invention, is achieved when the aminoplast resin functions as a di¬ functional monomer even though the resin has the capa¬ bility of higher functionality, e.g., tri- and tetra- functionality, as the case may be. Thus, more than one mole of a polyether diol to one mole of, e.g., a gly- coluril such as Powderlink 1174, represents a stoi- chiometric excess of the polyether to the glycoluril. Using this characterization, one may use between 1-2 moles of one of these reagents to 1 mole of the other.

¹ Powderlink 1174 is called a "resin" and "crosslinker" by Cytec, and has been sold under the Cymel® name (i.e., Cy el 1174). Its empirical structure is Cι ₂ H ₂₂ N ₄ 0 ₆ . Its chemical name is Imidazo [4,5-D] imidazole-2, 5 (IH, 3H) -dione, tetrahydro-1, 3, , 6-tetrakis ( ethoxymethyl)-. CAS 17464-88-9. It is also known by the fol¬ lowing names: (i) Glycoluril, 1,3,4,6 tetrakis methoxymethyl, (ii) Glycoluril, tetrakis methoxymethyl, (iii) Glycoluril, N,N,N,N tetrakis methoxymethyl, (iv) Glyoxal diuriene, tetrakis methoxyme¬ thyl, and (v) Tetramethoxytetramethylol acetylenediurea. The fa¬ vored name is (i) and such skeletal structure is called glycolu¬ ril.

Either the polyether or the aminoplast may be in ex¬ cess. However, it is more typical to use a mole amount of one reagent of about 1-1.75 to 1 of the other rea¬ gent. Typically, one employs a molar excess of the aminoplast resin because one may incorporate more hy¬ drophobicity into the copolymer this way. This is es¬ pecially the case when the copolymer is dimeric to oli¬ gomeric (e.g., possessing less than about 15 repeating units) . When making higher polymeric structures, one uses a greater proportion of the polyether reagent, up to a 1:1 mole ratio. In general, it is desirable to use a molar excess of aminoplast of about 1.001-1.5 moles to 1 mole of the difunctional polyether. The amount of monofunctional hydrophobe reagent, in the typical case, should not exceed about 2 moles, nor be less than about 0.001 mole, of the monofunctional hy¬ drophobe per mole of reacted aminoplast resin in the copolymer of the invention. Usually, the amount of monofunctional hydrophobe ranges from about 1 mole to about O.Olmole per mole of reacted aminoplast.

The use of aminoplast reagents leads to an unex¬ pected degree of formulating latitude in polymer syn¬ thesis . By varying the ratios of polyether and hydro¬ phobe components, it is possible to make a large number of associative thickener copolymers that impart ICI viscosity of 1.2 poise in flat paint at 4.5 lb. load¬ ing, but which give a range of 15,000 to 75,000 cen- tipoise at low shear. This latitude permits the fac¬ ile tailoring of associative thickeners for a wide va- riety of paint and nonpaint applications.

Waterborne coatings may be defined as coatings that contain water as the major volatile component and util¬ ize water to dilute the coating to application con¬ sistency. These coatings consist mainly of resinous binder, pigments, water, and organic solvent. The

type of pigmentation and the method of incorporation of the pigment vary widely.

Waterborne coatings can be made by dispersing, emul¬ sifying or emulsion polymerizing the resin binder by use of added surfactants. This technique leads to opaque liquids. Because some hard resins are difficult or impossible to disperse directly into water, the resin sometimes can be dissolved in a water-immiscible solvent, and the resulting solution dispersed by the use of added surfactants. In this case, the solvent aids subsequent film coalescence. Surface activity or water dispersability also can be introduced into resin molecules by chemical modification of the resin by in¬ troducing functional polar groups such as the carboxyl group.

Some very finely dispersed resins appear as clear or slightly hazy liquids; they frequently are described as soluble, solubilized, colloidal dispersions, micro- emulsions, hydrosols, etc. These resins contain built- in functional groups that confer water "solubility" upon the resin, and, normally, external added surfac¬ tants are not used.

Waterborne resin binders can be classified as an¬ ionic, cationic, or nonionic. Anionic dispersions are characterized by negative charges on the resin or by negative charges on the surfactant associated with the resin. Cationic dispersions have a positive charge on the resin or on the surfactant associated with the resin. Nonionic dispersions are those that have been dispersed by addition of nonionic surfactants or that contain a built-in hydrophilic segment such as polyeth¬ ylene oxide which is part of the main chain of a rela¬ tively hydrophobic resin molecule.

The coating compositions may be of the thermosetting or thermoplastic varieties. The resin used in forming

the coating may be insoluble in water, and the conver¬ sion of such a resin into a waterborne system typically involves converting the resin into an emulsion or dis¬ persion. In the context of this invention, the water- borne composition contains the aminoplast-ether copoly¬ mer associative thickener of the invention.

The aqueous polymer dispersions may be prepared ac¬ cording to well known emulsion polymerization proce¬ dures, using one or more emulsifiers of an anionic, cationic, or nonionic type. Mixtures of two or more non-neutralizing emulsifiers regardless of type may be used. The amount of emulsifier may range from about 0.1 to 10% by weight or sometimes even more, based on the weight of the total monomer charge. In general, the molecular weight of these emulsion polymers is high, e.g., from about 100,000 to 10,000,000 number average molecular weight, most commonly above 500,000.

The water insoluble resin may be any of those known in the art, and may be a conventional natural or syn- thetic polymer latex emulsified with one of a nonionic, cationic or anionic surfactant. The primary resins are based on homopolymerized and copolymerized olefinic monomers such as vinyl acetate; vinyl chloride; sty¬ rene; butadiene; vinylidene chloride; acrylonitrile; methacrylonitrile; acrylic acid; methacrylic acid; al¬ kyl acrylates; alkyl methacrylates; acrylamide; meth- acrylamide; hydroxyethyl methacrylate ("HEMA") ; gly- cidyl methacrylate; dihydroxypropyl methacrylate; ho¬ mopolymers of C2-C40 alpha-olefins such as ethylene, isobutylene, octene, nonene, and styrene, and the like; copolymers of one or more of these hydrocarbons with one or more esters, nitriles or amides of acrylic acid or of methacrylic acid or with vinyl esters, such as vinyl acetate and vinyl chloride, or with vinylidene chloride; and diene polymers, such as copolymers of bu-

tadiene with one or more of styrene, vinyl toluene, acrylonitrile, methacrylonitrile, and esters of acrylic acid or methacrylic acid, and the like. It is also quite common to include a small amount, such as 0.1 to 5% or more, of an acid monomer in the monomer mixture used for making the copolymers mentioned above by emul¬ sion polymerization. Acids used include acrylic, meth¬ acrylic, itaconic, crotonic, maleic, fumaric, and the like. The vinyl acetate copolymers are well-known and in¬ clude copolymers such as vinyl acetate/butyl acry- late/2-ethylhexyl acrylate, vinyl acetate/butyl maleate, vinyl acetate/ethylene, vinyl acetate/vinyl chloride/butyl acrylate and vinyl acetate/vinyl chlo- ride/ethylene.

Other waterborne systems involve reactive copolymers that are crosslinked by the presence of complementary functional groups in the system. For example, a co¬ polymer of acrylic ester/glycidylmethacrylate can be emulsified and crosslinked by the presence of a mela¬ mine-formaldehyde resin similarly emulsified in the system. In another system, a copolymer of HEMA and an¬ other acrylate, hydroxyl terminated polyesters, poly¬ ethers, or polyurethanes, can be emulsified and crosslinked by the presence of either an aminoplast resin, a polyisocyanate or blocked polyisocyanate.

The term "acrylic polymer" means any polymer wherein at least 50% by weight is an acrylic or methacrylic acid or ester, including mixtures of such acids and es- ters individually and together. The term "vinyl ace¬ tate polymer" means any polymer containing at least 50% by weight of vinyl acetate.

Even small particle size (about 0.1-0.15 micron) acrylic and other latices are thickened effectively,

and flow and leveling improved, by thickeners of the invention.

The amount of the aminoplast-ether copolymer de¬ scribed herein that is employed in the coating composi- tion of the invention is not narrowly critical. That amount will vary based on the resin system used, the water concentration, the amount of fillers and the choice of fillers, the presence or absence of thixo- tropic agents, and the like. Also, the amount of the copolymer will be based on how the copolymer is in¬ tended to be used in the formulation, e.g., used as a wetting agent or as a thickening agent. In that re¬ spect, the amount of the aminoplast-ether copolymer in the composition is sufficient to thicken the composi- tion or the amount of the aminoplast-ether copolymer in the composition is sufficient to function as a wetting agent in or for the composition. However, in general, the amount of the copolymer will range from about 0.1 weight percent to about 15 weight percent, preferably from about 0.5 weight percent to about 10 weight per¬ cent, and most preferably from about 1 weight percent to about 8 weight percent, of the weight of the coating composition, exclusive of fillers, pigments and like additives. Example 1

Carbowax® 80002 ( 300 grams , 0 . 0357 moles ) , Igepal RC-6203 ( 23 . 0 grams , 0 . 0338 moles ) , a mixture of dode- cylphenolethoxylates , were combined with 1356 grams toluene in a 2 liter reaction vessel fitted with a Dean Stark water trap . The mixture was refluxed under ni¬ trogen to remove water by azeotropic distillation . The Dean Stark trap was removed, and a distillation column was fitted to the flask . Powderlink 1174 ( 15 . 92 grams ,

² Poly (ethyleneoxy) glycol, M. . 8 , 000. Sold by Union Carbide

Chemicals and Plastics, Inc .

0.050 moles) was added and the temperature was raised to 100°C and Nacure 50764 (1.38 grams) (dodecylbenzene sulfonic acid) was added. Vacuum was applied to reduce the pressure inside the vessel to approximately 510 mm Hg. At this pressure the toluene distilled at a slow, steady rate. The toluene was constantly replenished to maintain a constant solvent level. This proceeded for 125 minutes at which time the viscosity was "X" on the Gardner bubble scale. The copolymer solution was cooled to 70°C. and dimethylethanolamine (0.53 gram) was added to quench the acid. The copolymer solution was cooled further to 60°C. and then poured out onto trays to air dry. The dried polymer was cut into small pieces and was dissolved at 20% polymer solids in a 4/1 water-diethylene glycol monobutyl ether mixture.

Example 2 Procedure for making associative thickeners without solvent Carbowax 8000 (2204 grams, 0.262 moles) Igepal RC620 (168.9 grams, 0.248 moles), and 500 grams of toluene were placed in a 12 liter vessel equipped with a Dean Stark water trap. The materials were heated to reflux to azeotrope off water. Once the mixture was dry the remainder of the toluene was removed with vacuum. Pow- derlink 1174 (117.0 grams, 0.367 moles) was added and allowed to melt out. After the Powderlink had melted the material in the vessel was transferred to a 5 liter sigma blade mixer preheated to 105°C. The mixer was turned to run at 20 rpm. Nacure 5076 catalyst (7.10 grams) was added and the top was placed on the mixer. Vacuum was applied (27/30 in. achieved) and held for 1.75 hours as the viscosity increased. When the mate¬ rial had become quite viscous the heat was removed and

³ Sold by Rhone-Poulenc, Surfactant & Specialties, Cranberry, NJ Sold by King Industries, Norwalk, CT

dimethylethanolamine (3.87 grams, 0.043 mole) in 10 grams of toluene was added and the mixture was allowed to stir for a further 30 minutes. Diethyleneglycol monobutyl ether (1850 grams) and deionized water (7200 grams) were added and the mixture was allowed to stir until the material had dissolved. The resulting solu¬ tion was filtered through a cone filter. Paint results are as follows: flat vinyl acrylic semi-gloss vinyl acrylic

(formulation below) : (formulation below) :

ICI:1.05 poise ICI:0.90 poise

Stormer: 104KU Stormer: 78KU

Brookfield: 49,000 Brookfield: 8,000 cps cps

Example 3

Using the procedure of Example 1, with the indicated modifications, the following other aminoplast-ether co¬ polymers were made:

Aminoplast-ether copolymer formulation

Reagent Concentration

Cymel 1171 (mixed ether gly- 0.0628 moles coluril) 5

Carbowax 8000 0.0349 moles

Tergitol NP-106 0.0489 moles p-Toluene sulfonic acid 0.53 grams toluene 1412 grams

Conditions: The maximum reaction temperature was 100°C. The reaction was carried out at atmospheric pressure (no vacuum pulled) . The Gardner scale was used in monitoring viscosity.

Reagent Concentration

⁵ Cytec Industries, Inc.

⁶ Ethoxylated nonyl phenol, sold by Union Carbide Chemical & Plas¬ tics, Inc.

Cymel 303 0.070 moles

(hexamethoxymethylmelamine) 7 Carbowax 8000 0.047 moles Tergitol NP-10 0.052 moles p-Toluene sulfonic acid 0.94 grams toluene 1,665 grams

Conditions: The maximum reaction temperature was 100°C. The reaction was carried out at atmospheric pressure (no vacuum pulled) . The Gardner scale was used in monitoring viscosity.

Evaluation In Semi-Gloss Latex Paint Formulation The 20% solution of example 1 was evaluated in a semi-gloss trade paint formulation, which consisted of a 24.4% PVC system using UCAR 376 vinyl-acrylic latex with Ti-Pure R-900 Ti02. Listed below are the rheological and application results for example 1 and two commercial nonionic associative thickeners.

Evaluation In Flat Latex Paint Formulation

⁷ Cytec Industries, Inc.

⁸ Rohm & Haas Company, Philadelphia, PA

⁹ Rohm & Haas Company, Philadelphia, PA

Example 1 4.5

Acrysol 4.5

SCT-270

Acrysol RM- 4.5

825

Procedure for making and testing latex paint using aminoplast based associative thickeners The following are the two primary formulations for evaluating aminoplast based associative thickeners. One is of a flat vinyl acrylic and the other is a semi- gloss vinyl acrylic. Typically both formulations are made in 5 gallon batches that are split into pints af¬ ter the grind and let-down stage, but prior to the ad- dition of the premix which contains the associative thickener.

The premix is added while the paint is being well agitated to ensure that the associative thickener is well incorporated into the paint. The paint is then allowed to sit at rest for 60 minutes to allow the ma¬ terial to further equilibrate followed by rheological measurements which involve —

1. viscosity measurement in Krebs Units (KU) on a Stormer viscometer (ASTM D 562-81) 2. high shear measurement in poise at 10,000 s-1 on an ICI cone and plate viscometer (ASTM D 4287-83)

3. pH and temperature measurements are obtained. The paints are maintained at room temperature (~23.5°C.) and are evaluated as above at 24 hours, 1 week, 1, 2, 3, 6, and 12 months with the following ad¬ ditions:

1. a syneresis measurement is obtained by determining the amount in millimeters of the clear liquid that may separate to the top of the paint

2. a low shear measurement is obtained in centipoise (cps) at 0.5 rpm on a Brookfield RVT viscometer (ASTM D 2196-86) . After the 24 hour rheological measurements the flat paints are evaluated for spatter resistance according to ASTM procedure D 4707-87 with the exception that the paints are rated by the amount of spatter produced from nil, trace, slight, definite and pronounced. After the 24 hour rheological measurements the semi-gloss paints are evaluated for gloss at 60°C. after 1 day and 1 week room temperature air dry of a 0.004 mil draw down. Also the semi-gloss paints are evaluated for sag and leveling according to ASTM procedures D 4400-84 and D 2801-69. The hydrolytic stability of the associative thicken¬ ers are determined by subjecting the paints to an ele¬ vated temperature (48.9°C.) for 4 weeks with rheological measurements obtained at 1 week intervals. The asso¬ ciative thickeners are determined to be stable if the Stormer viscosity does not lose more than 10% of the initial value.

Procedure for making latex paint

1. Add water (and propylene glycol for semi-gloss) to 5- gallon container, begin agitation on a Hockmeyer Model Lab 2 type disperser equipped with a 4 inch dispersing blade.

2. Add HEC for the flat formulation and let mix agitate 5 minutes at low speed (~1000 rpm) .

3. Add dispersant and mix 5 minutes, add other additives and pigment (s) and grind at high speed (-2000 rpm) for the specified time.

4. For the semi-gloss formulation prepare a premix in a separate container consisting of the water, HEC and

ammonia, ensuring that the HEC is well dispersed in the water prior to the addition of the ammonia.

5. Add remaining let-down ingredients and agitate for 40 minutes, check weight per gallon and pH, divide into pint containers.