CA1100992A - Bisulfite terminated oligomers as dispersing agents - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to the use of bisulfite-terminated oligomers as dispersants for solid particulate matter, i.e., low molecular weight bisulfite-terminated polymers containing carboxylate groups and either cyano or carbomethoxy moieties are improved dispersants for solid particulate matter like pigments such as titanium dioxide, clay, calcium carbonate, talc, and zinc oxide, as well as for organic pigments. Particularly, these dispersants have been round useful for stabilizing paper coating compositions.

Description

~1-3~

This invention relates to the use o~ bisulfite-termin~tcd olieo~ers as dispcrsin~ ~gents for thc prepara-tion Or dispersions of inorganic ~nd or~nic pi~ments, ~xt~nders, ~illers3 and other insoluble fine particles ~n aqueous systems~ The oli~omers hzve been ~ound es-pecially useful as components of p~er coatin~ colors to stabilize slurries of deflocculated paper coating p~gments. More specific~lly, oli~omers represented by the fo~lowing formula have been ~ound to be so useful:
- : . .
, H H ~. H H ~
C ~ - C _ C ~ C _ -S03 M
H X a H C00~' . .

wherein M is an alkali met~l or ammoni~m c~tion; X is .s~lected from -CN and -COOCH3; M' is a cation based on æmmonia, an amine, or alkali metal; a~b is from ~ ~o 250 and a/~b is ~r~m about 0 ~o not greater than 0.~ .
'' , The oli~omers whose use as dispersants for solid pa.rticulate matter is ciaimed herein, are disclosed in Canadian Pat~ 827,704 to L~ E. Dannals. This patent discloses a general class o~ bisulfite-terminated pligomers prepared ~ro~ a varie~y o~ mono~rs. This gener~l class of oligomers is stated to be useful as 25 conductive agents ~nd as surf~ace ac~ive a~ents. How-ever~ it has been found thæt the specif'ic oligomers useful f`or this invention are not surface active agents g~

in that ~hey ha~re no e~f`ect on the surface tension of watcr as is demonstrated by exarnple hereln.
Further~lore, it is well known to the art that the terms surface active agents ~ld dispersing agents are not synonymous; they represent dif~erent ~acets of a similar problem.
Canadian Patent 854,271 discloses fluid, aqueous clay dispersions containing sufficient polymeric poly-carboxylate to disperse the clay, where the polycar-boxylate dispersants are prepared from such as acrylic acid alone or acrylic acid and acrylamide copolymer or acrylonitrile and methacrylic acid copolymer. However, at no point is a bisulfite te~minated acrylic acid polymer nor is any acrylic acid-acrylonitrile copolymer disclosed.
Additionally, Japanese application 7123763 discloses an alkali metal salt o~ acrylic acid and methyl acrylate copolymer as a dispersing agent ~or paper pigments. However~ the pol~ners do not have a bisulfite terminal group ~rhich is essential to the ef ~ectiveness of this invention. Japanese patents 7136883 and 7233055 disclose similar dispersing agents where the comonomer with acrylic acid is acrylamide and itaconic acid respectively. U. S. Patent 3,5g4,203 discloses stable deflocculated aqueous clay slurries ln which a soluble salt o~ a polyanionic organic polymer including sodiwn salt o~ carboxylated pol~relectrol~ner is employed to impart the stability. U. S. Patents 3~736,165 and 3,737~333 discloses the use of the poly-anionic organic polymer in wet processing of kaolin-.

--2~

~3-clay as a ~ispersant to de~locculate the cl~y.
The use of sodlum polyacrylate as a de~locculant for paper coating pigments and a stabilizing agent in coating colors has been discllssed ~urther by M. E.
Rohmann, Wochenblatt fuer Papier~abrikation, 3, 79 ~1973)~
A paper coating color comprises three basic components: a pigment dispersion, a pigment binder, and minor additives. The pigment ~uch as kaolin or other clay, càlcium carbonate, titanium dioxide, satin white, and barium sulfate or com~inations thereof is dispersed in water using high speed dispersing eqvip-ment like a Cady Mill, Cowles Di$solver and Deliteur, or using a sigma blade mixer. Reagglomeration of the finel~ divided pigment particles is overcome by adding small amounts o~ certain dispersants including poly phosphates, naphthalenesulfonate-formaldehyde co~densates or polyacrylate salts. The pigment binder may be - natural or synthetic including such as casein, protein, starch, carboxylated SBR, polyvin~l acetate, pol~Jvinyl alcohol3 or vinyl acetate~acrylate copolymers. Minor additives include, besides the dispersant, crosslinking agents, optical brighteners, flo~ regulators, natural or synthetic thickeners, biocides, and de~oamers or an~i-foams. Although the dispersant is a minor component in ~ount~ it can have a pronounced e~fect on rut~ability of the coating color and on the final properties of the coated sheet.
The preparation o~ high solids coating colors, which are essential to modern high speed coating pro-. . _, . ~ ....... . ... . . .. .... . ... . . . . . . .... . ... ......... . ... . ... ..... .... . .

0~9~Z

cesses, requires dispersion o~ high solids slurries o~ pigments A disperslon of kaolin in water a-t 70 solids is a common slurry used in paper coating.
While the polyphosphates includin~ sodiun hex~meta-phosphate~ sodium tripolyphosphate, and tetrasodium pyrophosphate are highly efrective dispersants for preparation of ~luid high solids slurries, they have a tendency to revert to orthophosphates, which are ine~fective as dispersant. The reversion occurs under conditions o~ slightly elevated temperatures (over 25~C) i~ the slurries are stored ins-tead of being used i~ediately after preparation. This depolymeriza-tion of the polyphosphate produce-s instability in the dispersion, which is observable as an increase in the viscosity. Use of the organic dispersants, including naphthalene-sul~onate~formaldehyde condensates and polyacrylates, has been cited in t he references men-tioned a~ove. These organic materials impart stability to the slurries whether used in con~unc-tion with poly~
phosphates or used separately by themselves.
In addition, when latex containing a]kaline soap is added to a slurr~J where a polyphosphate is the s~le dispersant, ~he polyphosphates depolymerize~ the clay absorbs some o~ the soap, and the viscosity o~ the coa~ing color increases. The organic dispersants re-tain their e~ficiency and ensure constant viscosity o~ the coating color. Moreover, the polyacrylate salts are ef~ective when only a small amount o~ thé inorganic polyphosphate is replaced with it. There~ore, the - 30 polyacrylates ~unction no-t only as excellent dispersants, but also act as protective col:lo~ds with a high affinity for the sllrfaces o~ the paper coating pi~ment.
The properties o~ the final coa-ted sheet are improved ~n such a way that coating colors with increasing amounts of polyacrylates behave as if more pigment binder were present.
This invention is directed to the use of oligomers as dispersants. Such oligomers have hereto-~ore been kno~rn to be use~ul as conductive agents.
The dispersants are essentially non-foaming, completely water soluble, anionic polyelectrolytes especially designed for disper~ing solid particulate matter such as pigments, fillers, extenders, and other insoluble ~ine particles in aqueous systems. The resultant dis-persions are very stable to heat. Furthermore, formula tions containin~ reactive pi~nents such as zinc oxide or reactive additives like cationic bioc~des~ especially mercury ~ungicides, have much improved stability.
The oligomers ~hich are useful herein ma~ be represented by the following ~ormula:

~ H H I
H - 1- C - C - ~ -C - C - - S03M
L H X H COOM' L
a b wherein M is a water soluble cation; X is selected from -CN and -COOCH3; M' is a cation based on ammonia, an amine, or alkali metal such as lithium, sodium or potassium; a~b is about 4 to 250; and~a/a+b is from about 0 ~o not greater than o.6. In the preferred compounds M and M' are both s.odium.

.

6 1~ 2 Ti~e -invent-lon compr:Lses the use of the oll~orners as dispersants ~or particulate matter in water, and as -~
dispcrsants for the paper coating field in particular, as well as the ne~r dispersion compositions obtained.
The oligomers are useful in a range o~ 0.01 to 10 par-ts of oligomer~ preferab]y 0.0125 to 5 pærts of oligomer, and most preferably 0.02 to 3 parts of o-igomer per 100 parts of particulate matter.
It is unders~ood ~hat the formula is not intended to depic~ the actu~l structure o~ the oligomers, bec~use the structural units:
,_ H H H H
C _ C and C - C
H X HCOOM' . . .
are r~ndomly distributed throu~hout the molecule.
In the above generic formula the subscript "a"
indicates the total moles of the X-group, on the average, per molecule, and "b" the total moles of -COOMI, on the aver~ge, per molecule. The degree of polymeriæation, a-~b, is broadly ~rom about 4 to 250, and preferably ~rom 10 to 60 as a general dispersant and 4 to 50 in the paper coating ~ield. The mole fraction of the oligomer having the -X group as indicated by the ratio a/a+b is broadly from about O to not greater than o.6, pre~erably as a general dispersant 0.0 to 0.5, most pre~erably 0.0 to 0.40, while in the paper coating field preferably to O to 0.40, more preferab~y O to 0.20, and most prefcrably O to 0.10. When dispersing a p~gment such as titanium dioxide, zinc oxide, calcium carbonate, 30 clays and iron ox~des. the a/a+b ratio is preferably as low as possible, anc~ most pre:ferabl~ is 0.

, .. ,.. ,. ........ ; .

v _J~

Tl-c oll~romcr3 of thls invcntloll ~rc ~ro~luccd by theC~nOlymCr:l%~tion Or acrylic ~c~d ~r:lth ~crylo-nitrile or mct11yl acryl~.te in water and in the prcscnce o~ sodium bisu.lrite such th~t the a~ounts of e~ch species correspond to the desired levels of a and b in the product. The oligo.~ers so prepared are then neutralized ,~ith co~mon bases~ eOg., NaOH, KOH, NH3, etc. Further details o~ the preparation o~ oligorers useful in this invention 2re in Canadian Pat. 827,704 o~ Leland E~ D~nn~ls incorpor2te~ by reference herein.
.
The oligomers have been found use~ul for the preparation o~ stable dispersions for a wide varie~y ~:
o~ pigments and p~rticulate ~2tter especially titanium dioxide, zinc oxide, calcium carbonate and ka~in. The result2nt dispersions are themsel~es useful for compo~nd~
ing a~ueous polymer emulsions, especially for ~or~ula~
~i.ons o~ water based coatin6s. The required amo-mt of -oligomer necessary to disperse a particul~r solid depends upon the nature, particle size, and a~ount o~ the solid, the exact oligomer used, and the over~ll formul~tion involved, but usually would be no more than 3C~ by .~eight based on the solid content, except for the most difficult composition. The usual treatment level is ~rom about 0.01 ~o 10 parts by ~.~eight of oligomer dispers~nt per 100 parts of dry solids~ ~nd preferably oO125 to 5 parts9 and most preferably 0.02 to 3 parts. Bec~use of the high efficiency of dispersion ~^~ith the oligomers herein fluidity can be achieved at very high-solids levels with only a very small.a~ount of the oli~o.~er bein~ required.
Furthermore, the oliGomer may be uscd in con-_7~

~unction with conventional polyphosphate d~spers~nts so that an even lower level of oligomeric dispersant would be sufficient, preferabl~ from about 0.005~ to

2%, together with 0.5 to 7~ of` the polyphosphate to produce a dispersion with i~.proved stability over a long term. The lo~Jest and highest relative concentra-tions of the oligomer within the above concentra~ion ranges do not necessarily result in the lowest possible ~iscosity. The minimum ViSCosit~J which can be attained, however, will generall~ ~e found wi~hin these concentra-tion ranges.
The total solids of pigment which can be in- ;
corporated into the aqueous dispersion and still permit fluidity ~rill also vary depending upon the particular composition and the fineness of the solid particles being dispersed. These solids may vary from about 25~85~, preferably from 30-85~, but ~ill usually fall between 50 and 80~. The greater the amount of water, the lower the viscosi~y and the lower the amount o~
dispersant required.
Wh~le the pH of the resultant dispersions ~ould ordinarily vary from neutral to moderately alkaline, e.g~ about 7 to 11, ~he oligomers have been found to be e~fective dispersants over the broader pH range f 4.5 to 12. In addition, in those cases wherein the pH is customarily adjusted to afford an alkaline dispersion~ the adjustment may be made with, for examp~e, a~nonia, sodîum hydroxide, or- sodium carbonate.
The oligomer is obtained as an aqueous solution as the reaction product ~rom the polymerization. The -8~

. .
: . .. . .

-9~ 9 reactio~l product may ~e used as ~ additive for dis- ~
persing the partlculate matter ~ithout further purifica- ~ -tion or removal of traces of catalyst and monomer residues.
The reaction solids during pol~nerization are not critical as far as the utility of the oligomers is concerned. In addition~ the solids of the reactiQn product may be adjusted to any concentration to produce the solutlon of the oligomer ~hich is used as the 'r additive for preparation o~ dispersions. This con- -centrated solution o~ oligomer may contain any level of oligomer solids generally not exceeding 60~, but preferably between 15% and 3~, and~may even be as low as 100 ~pm, although this concentration does not affect the utility of the oligomer. The oligomer may also be recovered from the reaction mixture by any suitable means, such as spray drying, and used as a solid additive in place o~ the concentrated solution o~oligomer. When a pigment dispersion is prepared, a dilute solution of oligomer may be made by dilution of the concentrated solution or dry oligomer with the solvent (water), to which the particulate matter is added. Alternatively, a paste of the solid matter and diluent (water) may ~e formed~and the concentrated solution or dry oligomer is then added to produce fluidity.
A wide yariety of solid particulate matter may be dispersed using the oligomers. They include all common pigments and extenders or other-materials commonly used as fillers, ~nd may be combined trith any organic or inorganic colored pigments as desired, and may be for~u-_9 _ .. , .~.. o ,, .. . , . . . ~ .. . . .. . . , .. .. .... , .. . . ... ~. . .... . ... .. . . . . . . . . . . . .

-~~ Z

lated wlth any o~ the usual addltive~ WlliCil are employed ln compoudning wlth pi~ments. The dispersions of the pigments t~ri.th appropriate additives are used especiall~ for compounding aqueous polymer emulsions, including those designed for water base coatings, especially ~or paint and p~per coating. The pigments and extenders ~hich m~y b e dispersed to ~orm a white pigment base to which additives including colored pig-ment would be added, may be any insoluble ~inely divided substance, ~or example, titanium dioxide, zinc oxide, calcium carbonate (whiting3, cla~ such as china clay or kaolin, talc, silica, mica, barytes, etc. Colored ; i~
pigments suitable herein include, for example, chrome yellolw, molibdate orange, iron blue~ chrome green, cadmium red or ~ellow, iron oxide red or yellow, chrome oxide green, ultramarine blue, mineral violet, cobalt blue~ titanate yellow, as well as organic pig-ments like dichlorobenzidine yellows and oranges, hansa yellows, dinitroaniline orange, na~hthols, toluidine red, lithol reds and rubines, BON reds and maroon, phthalocyamine blues and greens, quinacridones, isoindolinones, perylenes, etc. The dispersion of these pigments are use~ul for compounding emulsions ~or any applicatlon in which t,he compounded emulsions are used, but especially for applications in paints,paper coating, or other surface coatings, and adhesives which employ fillers. The powdered ~aterials are mixed with a solution of dispersant in a solvent (water) in t~hich they are insoluble. The ensuin~ paste may be ~round in a mill as desired; how-ever, a high shear miY~er may be suitable lor producing fluid dispersions. Various a~ditives may be included --~.0- :~
- s . ~",; ";~ ,,", " " ~ "

in th~ dispersion. The most common additives ~or paints and ~or paper coating are preserv~tives and bio-cides including germicides, bactericides, and fungicides, thickeners, de~oamers, coalesc:in~ solvents, plasticiz~rs~
and crosslinki~g agents.
The dispersion viscosity is measured with a Brookfield viscometer (RVT). In the evaluation, dis~
persion viscosity measured at 50 rpm in excess of 20,000 mPa.s (milli pascal seconds) is unacceptable; pre~erably the viscosity should be less than lO,000 mPa.s but is not expected to be less than lO mPa.s. In a simple formulation Or particulate matter, ~later, and dispersant at up to 75~ solids, viscosity between 10 and 2~000 mPa.s is most preferable. For a formulation of paper coating clay, with pigment solids bet-Jeen 60~ and 70$, the viscosity may range bet~reen 50 and 5,000 mPa.s.
For a ~ully formulated paint pigment dispersion but without thickener, at 70,~ to 75~ pigment solids, the viscosity may range bet~lreen 100 and 10,000 mPa.s.
Fluid dispersions can be prepared using oligomers within the scope of the invention; however, the re-sultant viscositles are more favorable within the preferred r~nges of alb and a/a+b.
In order to illustratç more clearly the instant invention, attention is directed to the following ex-amples:
EX~MPLE 1 .
A typical laboratory prepar2tion and testing procedure for dispersion properties of an oligomer of the invention, wherein X is -C~, M and M' are both ~11~ .

sodium, a~b is 15.5, and a/a-~b is 0.35~ as described:
The followin~ materials are com~ined in a 1 liter resin ~lask.
280 ml water 16.1~ g Sodium bisulfite (9.2 phm~
. o.o88 moles) 110 ml (115.5 g) acrylic acid (65.1 phm, 0. 904 moles) 57 ml ( t45-6 g) acrylonitrile (25~7 phrn, o.485 moles) The mixture under agitation is equilibrated in a water bath controlled at 30C., while nitrogen is allowed to ~low through the reactor. ~mmonlum persul~ate, 10% solution~ is added incrementally ~rom a burette using 0.25 ml aliquots every hour for two hours and again at 2-1/2 hours, (a total o~ 1 ml is used) when no further exotherm is detected ~rom the temperature o~
the reaction. The maximum temperature reached during polyrnerization is 33~6C.
The Brookfield viscosity (RVT) of the solution is 600 ræ a.s at 38.9~ total solids~ The solution is neutralized to pII 11.5 with 115.0 g o-~ about 50~
sodium hydroxide. The neutralized oligomer solution has a ~rook~ield viscosity o~ 330 mPa.s and total solids o~ 39.2~. A on~ g.ram portion of the reaction product is converted to its methyl ester in a boron tri~luoride-methanol mixture, and the average molecular weight determined by va~or pressure to be 1150. A portion o~ ;
about 200 ml o~ the reaction product is also diluted to a 25.0~ wt. solution o~ oligomer to serve as a concen~
trated solution o~ dispersant.

The dispersin~ properties of the ol;gomer are evaluatcd by preparation of solid particulate matter ,, dispersions as follows:
~eighed amounts of the solid particulate matter and water are mixed together using a spatula until a moist stiff paste is formed. The paste is then ~reated with increments of the concentrated solution o~ oligomer.
After each additio~, the paste is mixed for one minute using a laboratory mixer at high speed in attempts to disperse the solld matter. When sufficient dispersant has been added, a fluid dispersion is obtalned ~der agitation. During the titration, Pluidity is achieved suddenly ~Tith the addition of onl~y a very small additional increment of dispersant. The Brookfield viscosity is measured when the dispersion first becomes fluid, and again every time after additional amounts of dispersant -are added. The incremental addition is continued until a minimum viscosity is observed. The results of such fluidity titrations are given Por the oligomer described above in Tables I and II, ~herein titanium dioxide and zinc oxide are used as the solid matters~ respectfully.
TABI~ I
Dispersion of Titanium Dioxide with Oligomer oP Ex~nple 1 ?5 Formulation: 71.4C~ pigment solids: 250 g titznium dioxide~
ru~ile 100 g water Concentrated Solution of Oligomer: 25.0% wt.

_~3.

Brool~ield Viscosity (RVT), mP~.s ~at~o~ ~ 100 rpm~ S~indle 1,~3 , o. o6~ ~looo . 079 8~5 ;
o. ogo 5~4 0. 102 1~79 0.113 393 ~;
0.]24 3~9 o.~36 ~ 3~7 0,147 336 0.181 430 0.226 (2) ( 466 (1) Pærts of Oligomer/100 pærts particulate matter.
~This term has the same meaning throughout Tables I-IX).
(2~ Final pi~ment solids - 71.0 T~BI.E II
Dispersion o* Zinc Oxide with Oligomer _ ~ ~xa~ple 1 Formulation: 71.4% pigment solids: 250 g zinc oxide ~coarse) 100 g water Concentrated Solution o* Oligomer: 25.0~ wt.
Brook~ield Viscosity (~VT)g ~pa.s Ratio ~ ~ b~
o.o6~ ~looo 0.079 447 o.~go 162 0.102 122 0.113 ` 107 0~ 124 100 o.136 9~ ' 0.163 96 0.192 103 ?26 (1) . lo~
~1) Final pigment solids - 71.0 Examl?le 2 The procedure of Example 1 is repeated to pre-pare ~,n oligomer wherein X is -CN, M ~nd M' are both sodium~ a+b is 20.9, and a/a~-b is 0.32 The resultant oligomer is used as a dispersing agent for various particulate matter as shol~m in the fluidity titrations o* Tables lII-VI below.
.

. -15- :
~.

TM3I,~ III
D.ispcrsion o~ Ti-t~n:ium Dioxi~e wi~,h Oli~omer o~ Exam~le 2 ... . ~ . .
Formulation: 75.0~ pigment solids: 225 g -titanium dioxide, rutile . 7~ g water Concen-trated Solution of Oligomer: 24.5%
Ratio Brookfield Viscosi.ty :~:
(RVT), mpa.s 100 rp~n, S~indle 0.123 ( ~1000 .
0.1~ 5 0.1'72 ~10 .-0.197 606 1~ 0.222 682 .
0.246 (1) . 863 .
(1~ Final pigment solids - 74 . 5%
TABLE IV
.
. Dis~ersi.on of Zinc Oxide l^~ith Oli.gomer of Ex~mple ?
Formulatio~: 60.~ pigment soli~s: 180 g zinc oxide 99.55' 325 mç.sh . 120 g water :~
:Concentrated Solution o~ Oligomer 24.5~ . . .
Ratio Brookfield Viscosit~r (RVT)~ mpa.s . .
loo rpm~ Spindle ,1~3 ~ .
0.123 ~1000 O. 154 304 O. 18l~ 92

3 O. 216 .gl~
O. 261 ~.08 O. 308 118 O. ~8~ 137 o.463 . 156 0 . 617 164 o.769 (1) . 170 (1) Final p-gmen~ solids - 59.0 . ' , .

. -15- .

:

~16-..

T/lBhE: V . ., Dispersion o-f` Calciwn Carbonate with Oligomer of E~am~le 2 Formulation: 75.0~ pigment solids: 225 g ca].clum carbonate, 92.9~ 325 mesh 75 g water Concentrated Solution of Oll~omer: 24.5% ;~
Ratio Brookfield Viscosity ~ :
(RVT)~ mPa.s 100 rpm, Spi.ndle ~3 0.012 ? 1000 0.025 7~6 9 37 ~ 1~49 o, o49 362 ' 0.061 ` ~ 342 ~`
o. Q86 318 . . 0.123 302 : ::
0.172 312 0.233 (1) 339 (1) Final pi~lent solids - 74.5 TABI.E VI
'~
Dispersion of No. 1 Coa~ing Clay with Oligomer o~
E~a.m~le 2 Formula.tion: 61.0~ pigment solids: 350 g wet ~ilter cake ~oncentrated Solution of Oligomer: 24.5~ -~
Ratio Brookfield ~iscosity (RVT)~ mpa.s _ Spindle ~3 00 rpm 10 rpm 0.. 299 ~ 1000 --0.312 365 1250 0.325 173 420 o.338 128 200 0~ 351 98 140 0,364 (1) 102 130 (1) Final pigment solids - 60.5 ~lG~

17 ~ 2 ~

Forrnula~ion: 60.5,' pi~ment solids: 3l~5 ~ dlsperse~ clay cont~inirlg 0.76 dispersant ~o~ g clay 13~ ~ water Dry Clay* Ratio Brookfield Viscosity Added (RVT), rnpa.s Spindle j"3 100 r~m 10 rpm , o o o . 364 102 130 o. 368 12~ 210 0. 395 139 310 o. 418 198 520 o ~44 296 720 loO ~ 488 4~13 . 1330 120 ~2) 0.518 ~1000 2850 (2) Final pigment solids - 70.~ ~
* Dry clay is added to raise the solids in the dis-persion. After each addition, su~ficient dispersant is also added to keep the viscosity at its minimurnO
Exam~les 3 - 23 The basic procedure of` Exa~ple 1 is repeated to prepare numerous oligomers wlthin the scope of the invention. The ollgomers are then tested for dispersant properties in normal co~nmercial-type for~,lulations con-taining l,~ater and ethylene glycol as coalescing solvent, the oligomer dispersant, a mercurial fungicide, and a de~oamer. The dry pigment and e~tender are added to the aqueous solution of additives under slo~l~ mixin~.
The resultin~ paste is ground for five minutes with h:igh speed mlxing to produce the fluid d:Ls~ersions.
The Brookfield viscosity is then measured. Under high speed agitatlon, the dispersion is heated to 125F., at ~rhich temperat~lre it is maintained for ten minu-tes if the dispersion remains fluid. The viscosity is then measured again. The composition of the tested oligomers are listed in Ta.b~e VII c~nd the results of the evaluations ... ...... ,...... . ................. ~ . . ...... .. .. ~......... .
,, ~

are compi].ecl in T~bles VIII and IX. The data demorlstla~e first that ef~iclellt dispers:ions are obtaine~d for any ~-~b throughout the rz,nge tested~ next that only small amounts of di.spersant are required to ensure fluidity, and ~inally that the d:ispersions remain stable to heat even in the presence of reactive fun~i.cide.
TABL~ VII
Composition o~ Oligomers: M,M' are Sodium.
X is ~CN
Ex~l~le a/a+b a-~b Concentrat-lon* ~ol`Jt.)_ 3 0 13,9 32.8 _ ' -

4 0.17 20.1 1~6.1 25.0 0.26 34.5 ~6.o 24.~
6 0.31 50.6 3~.7 24.6 7 0.32 20.9 38.7, 25.6 8 0.35 15~5 39.~ ~5.Q
g 0-35 30,l~ - 38.g ~ A = final concentration of reaction product a~ter ' ' polymeriæation.
B = reaction product diluted with ~ater to concentra-tions indic2ted.
T~BLE VIII

Fo,rmulation: 250 g titanium diox:Lde, rutile ~ 70~
100 g talc ~ pigment 126 g water ~ 2l~ g ethylene glycol ~ solids

5 g'30% phenyl mercuric acetate 1 ~ Cofoa~ ~2*
* Cosan Chemical CompaM~J Trademark for proprietary defo~mer.

-].8-~ .. ~ .. . ... . . . .
... ~

9 ~ 32 _ _~sc~ i.t~r _ ~
Pol~ner ' (3) BC~ore A~ter ~:
.xample Solut_.on Ratio l~eat~
3A .93 1260 1140 12 ~B .89 680 420 13 6B .8l~ gl~o 420 1~ 7B .88 690 ~10 8B .89 680 420 16 9A ~ .88 670 3~0 (1) See Table VII
(2) Brook~ield V:iscosity (RVT), mPa.s, Spindle ~t3, : :
50 rpm Same . . meaning in (3) Parts oligomer per 100 parts o~ pigment at Table IX
68~ pigment solids TABLE IX
Evaluation o~ Oligoners 3 through 10 .Formulation: 250 g titaniun dioxide, rutile ~ 75 ~ 200 g talc ~ pigment : 126 g water ~ 24 g eth~lene solids . glycol . 5 g 30~ phenyl mercuric acetate 1 g Cofoam #2 ' Vlsco~it~r - ~
Polymer ~1~ Be~ore A~ter Example Solutlon Ratio~ ~ Heating Hen_inrr, 17 3A .73 11110 7230 18 ~B .50 5Q90 4940 l~B .67 451~o 2640 19 5B ,49 4420 3620 5A .71 4520 3280 6B .-55 6430 5130 6B .65 595 4080 7A .69 5210 22 8B .56 9960 6480 8A .70 6520 3580 23 9A .61 6290 4200 9A .69 7240 3610 ~3) Parts o~ oligomer per 100 parts of pigrnent at 73% minimum pigment solids.
Exam~les 24-36 J' The ef~ect of various oligomers ~rithin the , scope of this invention on the surface tension o~ dis-tilled water was determined. The result,s, as sho~m in Table X, prove that the oligo~ers use~ul as dispersants have no surface active properties. They have no e~ect in reducing the interfacial tension between water and air, i,e. the~ do not lo~er the sur~ace tension of water.
The seeming increases of sur~ace tension values ~or the solutions containing the compounds of the invention are attributable to structural and viscosi-ty phenomena.

-2Q~

~21-A typical surfactant, thc T)ot~.sr~um salt of a compound having similar structure and composition with the e~ception of the terminal group being ~S-C8~1 instead o~ -S03Na, shows a drastic reduction in the surface tension o~ water, and is listed in Table X ~-below as "Comparison"0 TABLE X
__ __ , Surface Tension of Oligomers X is -CN~ M and M' are sodium~ except Ex. 37 10Example a a~b Goncentration (~ wt.) dynes*~cm.
_ a~b _ _ 21~ 35 15.5 24.9 77.3 0.18 33.6 25 0 78.7 26 0 31 50.6 24.6 76.9 15 27 0 17 20.2 24.8 69.o 28 0.26 34.5 2~.8 77.7 29 0.35 30.4 24~9 76.9 0.32 20.9 0.1 73.0 31 0.32 20.9 ~5 73.2 20 32 0.32 20 9 2.6 72.~
33 0.32 20.g 4.~ 72.0 - 34 0.32 20.9 24.5 76.2 0.45 ~31.3 24.5 7~.6 ~36 ~.42 21.2 24.7 73.7 25Com~ari-son 0.50 16.0 0.1 48.8 *Uncorrected, DuNouy Interfacial Tensiometer~ ring cir-cumference -- 5.991 cm.
Surface tension, distilled ~rater, room temperature, measured 71.8 dynes/cm.
Example 37 The procedure of Example 1 is repeated to prepare an oligomer ~hereln M' and M are both sodium, X is -C02CH3, alb is 15.8, a/a~-b 1s 0.351 The resultant oligomer is used as a dispersing agent for the formulation previously described in TABLE IX, l~here Ratio of oligomer~100 parts particulate m~tter is 0.61, the Viscosit~J (Brookfield (RVT), Spindle ~3, 50 rpm) before and a~ter heating is 4550 mPa.s and 2810 mpa.s respectively.

.

Example ~,8 This ex~nple sho~rs the use of a dispersing agent o~ this invention.
The follolring pigment ~ormulation is ball ~;
milled ~or ~4 hours: ~-~2 parts water 2 parts of the 25% solution o~ oligomer from Example l 55 parts zinc oxide, 99.5~ through 325 mesh The resultant pigment slurry is next compounded inthe following latex formulation:
162 parts natural rubber latex, centr~uged to 62~ `
2 parts 50~ potassium hydroxide 1-5 parts zinc oxide slurry from above The compounded latex is mixed thoroughly and then used as a dip for casting rubber films. The zinc oxide is customarily used in this composition topromote curing o~ the rubber ~ilm. In order to obtain a satis-, .
~; 20 ;~actory cure, however, the zinc oxide must be predispersed so that any agglomerates of it are broken down to ultimate particle size.
After the rubber is cured, the ~ilms are checked to ~e certain that the physical properties o~ the rubber are satisfactory. Then, the films are stretched and placed under an optical microscope to determine if there i~ any agglomeration o~ the zinc oxide.
Samples containing l, 2, 3, 4 and 5 parts, re-spectively, o~-the zinc oxide slurry are all found to have no evidence of pigment agglomer~tion.

, :... .. : ; ., ~ . , -23~

I~ th~ oligomer i3 omit-~d from making the slurry, th~ ~inc oxide do~s no-t slurry, and if it does not slurry, then it can not be 2dded to the latex.
Exa~ple 39 A typical test for illustrating the dispersing and stabilizing properties of the oligomer of Exc~m~le 1 was as follows To prepare a slurry of kaolin clay - (Ultrawhite 90 - Englehard ~Iinerals and Chemicals), 0.25~ TSPP (tetrasodium pyrophosphate) is added to an undispersed filter cake of clay (60% solids~ under lo~ shear agitation. The solids are raised to 705~
by adding clay which had been dri'ed at 103C overnight ~nd repulverized with a 'hammer mill. Sufficient TSPP
is added to keep the concentration at 0.2~ based on the dry ~reight of clay. This high solids cornposition is mixed under high shear agitation (sigma blade mixer) for 5 minutes. After the tempe-~atur~s i5 allo-:red to come belosr 25C, the Brookfield viscos-Lty (RVT) is measured. In increments not greater than 0.05~0 TSPP, additional TSPP i~ added. After each addition, the slurry is ~round, allowed to cool, and the ~iscosity is observed. Additions are repeated until ~ minimum vlscosity is obtained. In this exc~mple 00375~ TSPP
is ~ound to give the minimllm vi~cosity at 70.~,~ clay solids To the final optimized s]urry the orgc~nic dispersant is added and mixed thoroughly, followed by addition of 0.055~ of the germicide 3,5-dimethyltetrahydro-1,3,5-2H-thiadiazine-2-thione (Metasol D3TA, Merck Chemical). The initial reading of pH, solids, and .. . .. - ., ~ ~ .:

U~Z

viscosity are recorded and samplcs are placed in a shalcer bath pres~t at 45~. Subsequently, s~mples are removed from the bath, allow to cool to 25C, readi.ngs o~ pH, solids, and viscosity are recorded, and the samples are returned to the bath. The observations are made a~ intervals ~or 30 days. The results when oligomer of Exarllple 1 is used are given in TABLE XI.

. .........

` 25~

_TABLE XI
Stabil:izatlon of Clay Slur~ies~ A~,ed at ]10F
__ ____ 0.370~ TSPP
0.05~ Metasol D3TA Brookfleld Viscosities (RVT) ancl Clay Sollds Organic lime Dispersant O 1 ~k 2wk 3wk 4wk nonelOOrpm 461L 1218 2180 3510 4870 lOrpm 1110 5500 12640 20100 25000 Solids 69.869.5 59.7 69 . 6 70 . o pH 6.5 6.o 5.8 5.8 5.8 OllgomerlOOrpm 555 635 772 912 912 o~ ~.1lOrpm 1690 1890 2290 2800 2880 at 0.01~Solids 69.870.0 69.3 70.0 69.9 pH 6.5 6.o 5.8 5.8 5.8 OligomerlOOrpm 730 728 593 532 581 o~ Ex,llOrpm 3330 2800 1850 1480 1630 at 0.02C~ Solids 6905 69.9 69. 6 69.5 69.7 `pH 6.5 6.o 5.8 5.8 5.8 OligomerlOOrpm 500 495 606 66~ 83~
of h'x.llOrpm 1950 1950 2430 2450 2360 at 0.015~ Solids 72.471.8 72.1 72.6 73.0 p~l 6.1~6.o 5.9 5.9 5-8 Oligomer lOOrpm 695 425 545 662 95LL
of }3x.1 lOrpm 3010 1420 1770 2000 2340 at 0.024% Solids 72.471.8 7200 72.7 72 . 6 pH 6.1~6.o 5.9 5.9 5.
Oligomer lOOrpm ~65 354 47 546 728 o~ Ex.l lOrpm 1440 1040 1480 1710 1980 at 0.03ll~ Solids72.572.2 71.8 72.5 72.6 ; pH 6.4 6.o 5.9 5~9 5.8 ~ le ~0 To pre~are a coating color containing the Ol~gomer o~ E~ample 1, the ~ollowing procedure is fol-lol~ed: 250 g of Ultræ~:Jhite 90 (dry clay), 97 g water, 1,26 g TSPP decahydrat~, and 1 g 25~ sclution of oligo~.~r o~ Example 1 are combined ancl mixed ~or -ten minutes in a sigma blade mixer. At the end of the mixlng 10 g additional water i5 added to dilute the slurry to 70'~
~G clay solids. The coating color is prepared by cornbining ... .. . . .. ..
.. . .. . .

-2~ 2 . .

300 g o:~ ~h~.7~5 cla~ slurry and 147 ~ 20,~ starch Penrord Gurn 390, precook.ed ~t 9G~C for 20 rninutes).
The coati.n~, color is tninned b~J ~ .utin~ to l~o~ with water and is applied to uncoated paper with a ~/5 ~lound wire applicator a.nd dried. The f:inal coating sheet so far ob-tained c~ be ~ur-ther mechanically processed, for exa.mple, by calendering to produce a high gloss coated paper. The pap~r exhibited excellent properties .
with respect to bri~htness~ opacity, gloss, surface :~
strengt`, m ~ abso~bancy, snd smoothness.

' --2~-... ........ . . . .

-27- ~
~, f ExamQles 41-4~ ~
The basic procedure o-f Examples I ~as repeated f to prepare additional oligomers w.ithin the scope of the in- j venti~n wherein ata~b = 0. Ihe oli~omers were then tested for . , dispersant properties according to the procedure described in Example 39. In addition the oligomer of Example 3A was also tested in the ~ormulation of Example 39. The composition of t the tested oligomers are listed in TABLE XII and the results , of the evalu3tions are compiled in TABLE XIII. --TABLE XII
.,': '' ' ' '. ' .' ~ .
Composition of oligomers: M,M' are all sodium a/.~ = 0 .. , , . . ,....... , . I
F~s~ a +~ b ; . Co~cc~ ~ rot i on~ ~ L ~ f 41 5.8 1~7 3%
42 6.6 36.1% ~.1%
43 . ~.2 46.9% - . ~
4~ 56.4 35-7% --, L

* See TABLE VII
.t TABLE XIII
. .
Stabîlization of Clay Slurries, Aged at 110 F-. ~

0.35~ TSPP . t 0.05% Metasol D3TA Brookfield Viscos;ties~RVT) _ __ and Clay Soli~s ol igomer Time 0 1 week 2 weeks 3 weeks 4 weeks ~olution ~_ 6.5 6.0 ~.8 5.8 5.8 ._ . . __. _ _ ~lA ~ rpm 370 370 440 400 400 @ D.031% . lO.rpm 1070 930 ~o60 960 1040 Solids 70:7 7~-7 70 4 70.6 70-7 43A 10~ rpm - 330 43Q -370 420 3~0 0.032% 10 rpm 940 106U 91~ 1010 940 -?~

TABLE X~ cont.
.
ol igomer Time 0 1 week ~ ~eeks 3 weeks 4 ~eeks SoTution __pH 6.5 _ 6.0 5.8_ 5.8 _ 5.8 3A 100 rpm 567 547 516 481 4~6 0.027% 10 rpm 1650 1590 1440 1300 1390 Solids 70.0 70.4 70.4 70.4 70-5 .
'' . , . :
~xamples 45 ~ 46 . . ' . The dispersing proper~ies of the oligomers of Examples 42 and 44 were evaluated further by preparation of .
dispersions of solid particulate mat~er according to the pro-cedure described in Example above. The results of the fluidity titrations are shown in TABLES Xl.V -XV
. .
' ~ ' , ' ' -~ ....... . .. .
TABLE XIV

Dispersion of Titanium Dioxide with Oligomer of Example 42.
For,~ulation: 71.4% Pigment Solids: 250 9 titanium dioxide rutile : 100 g water Concentrated Solution of Oligomer: 42B, 25.1% Solids . Brookfield Viscosity ~RVT) Ratio 100 rpm, Spindle #3, mPa, s 0~0~7 796 0.071 486 0.075 347 0.080 251 0.0~5 22~
0.~5 188 0.1!1 186 0.124 ` 188 0.148~ - 212 0.200 ~5g ~1) Final pigment solids 71.0%

'-~g~

TABLE XV -.
~.............. ,. , Dispersion of Zin~ bxide with Oligomer of Example 44 ¦~
Formulation: 71.4% Pigment Solids: 250 g zinc oxide (coarsé) 100 9 ~ater Concentrated solution of ol igomer: 44A, 35.7% Solids BrookfTeld Viscosity (RVT~ .
Ratio . 100 rpm, Spindle #3, mPa.s_ 0~069 ; . lD00 0.082 - ~83 . .
0.102 - 283 . . ,~
0.130 . 180 (1) 1~5 (1) Final pigment solids - 71,0% .
.. . . .
: - . .

,

Claims (3)

What is claimed is:

1. A dispersing agent for solid particulate matter in aqueous systems consisting of an oligomer having the formula wherein M is an alkali metal or ammonium cation; M' is a cation based on ammonia, or an alkali metal; and b is about 4 to about 250.

2. The dispersing agent of claim 1 wherein b is 4 to 50.

3. The oligomer of claim 1 wherein M and M' are both sodium.