Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2Q6~
SPECIFICATION
BRIEF DESCRIPTION OF THE INVENTION:
This invention relates to a weak organic
solvent-based liquid system, particularly an aliphatic
hydrocarbon based liquid such as a colored ink, the
thickener therefor, a method of making the thickener pre-
ferably by emulsion polymerization, and a method of using
the thickensr. The novel thickener is an acrylic copolymer
of hydrophobic and hydrophilic monomers, specific preferred
copolymers being of isobutyl msthacrylate and one or more
acids selected from acrylic acid, methacrylic acid and
itaconic acid in weight ratios of between about 99.9:0.1
and 90:10 with narrower ranges being praferred. The pre-
ferred acid is methacrylic acid. Other eth~lenically un-
saturated addition-polymerizable hydrophobic and hydrophilic
monomers are useful in place of or with the preferred
monomers, as long as the thickensr is soluble in aliphatic
hydrocarbons and has molecular weight limits which cause
it to function as a thickener in such a system. The organic
solvent is preferably at least predominantly an aliphatic
- hydrocarbon, for example a mixture thereof with a minor
amount of an aromatic hydrocarbon. Particularly beneficial
is the use of this thickener in gravure inks.
The uses of these weak solvent-soluble thickener
polymers include:
l) Thickeners for Type A and Type B gravure
inks, a preferred use.
2) In sealants and caulks for masonry
~) Textile pigment printing inks or paste
3 auxiliary.
~k
~06~1
4) Toughening modifier for powder coatings.
5) Binder/molifier for wet and dry toner systems
- Electrofax, Xerography, and related
electrophotographic techniques.
6) Anti-sag additive for hot melt adhesives.
i 7) Thickeners for aliphatic hydrocarbon
! systems in general.
The thickener polymer is uncrosslin ed. That
is, èssèntially no polyunsaturated addition-polymerizable
monomers are used. Any inc;dental crosslinl~ing of the
polymer prior to its application to a substrate. as in the
~orm of an ink, i9 such as not to destroy the compatibility
of the polymer with the solvent~ binder, etc.
BACKGROUND OF '1'~ INVENTION:
Metallated rosin inks for gravure printing
commonly contain ethyl cellulose or ethyl hydroxyethyl
cellulose as a thickener. However, the prices of ethyl
cellulose and of other cellulose derivatives has escalated
to an extent that a substitute (partial or complete) is neeaed.
As is know~, limed rosin has long been used in similar inks
as is noted in U.S. patent No. ~,409,449, which gives
suitable dyes and pigments for use in such inks.
, . ~
U. S. patent No. 2,886,549 is concernsd with
aliphatic hydrocarbon (benzine) soluble acrylic polymers
for use as lacquers, inks, and textile impregnants. The
polymer is solution polymerized at 90C. and 120C. which
would give a low molecular weight polymer, and molecular
weight (not specified) can be controlled with conventional
polymerization regulators. The polymers have at least two
- componsnts, with a third optional component. The first
-- 2 _
i
component (50-90 parts) is a cycloalkyl ester of an unsat-
urated acid such as acrylic acid, methacrylic acid or
fumaric acid, etc; the preferred alcohol moiety is, for
example, cyclohexanol, mono-, di, or trimethyl cyclohexanol,
or other substituted cyclohexanol. The second cornponent
(10-50 parts) is an ester of (meth)acrylic acid with an
alcohol of at least eight carbon atoms, preferably 10-18
carbons. The third and optional component (1-20 parts) is
a different polymerizable compound such as vinyl acetate,
styrene, etc., or one having a reactive aldehyde, epoxy,
carboxy, etc. group. Of the examples, Example 1 (80 cyclo-
hexyl methacrylate (C~A)~ 20 dodecyl methacrylate (~[A))
gives a polymer with the highest calculated Tg of the
examples -- just below 30C. At 90 C~A and 10 DMA, the
calculated (not actual) Tg would be about 45C. As else-
where herein, unless specified otherwise, the Tg is the
calculated value using the method of Fox (infra). At 50
CHMA and 50 ~A, this value would be -15C. Being solution
polymerized at high temperature~, the polymer would have a
quite low molecular weight.
A similar disclosure of alkane (ligroine or
benzine) soluble acrylic polymers appears in British patent
No. 772,746, which, based on CAo 51, 10925f, involves a co-
polymer of 20-40~ of a higher alkyl ester such as dodecyl
methacrylate or cyclohexyl methacrylate, with styrene and
the like. An example is given of a polymer in parts by
weight of 680 styrene, 320 dodecyl methacrylate, and 200
methyl methacrylate. This would have a calculated Tg of
about 36C. and, because of the polymerization method, a
very low molecular weight. If it is assumed the polymer
.
- 2a -
~3~Z~ 6 ~ ~
is 20 CHMA and 80 styrene, the calculated Tg is about 90C.
whereas with 20 ~MA and 80 St the figure is about 50C.
The polymer may be combined with other coating materials
such as drying oils, phthalic acid resins, etc.
A condensation polymer, of a copoly~.er of
acrylic acid-butyl methacrylate-methyl methacrylate with
rosin modified by glycerol, fumaric acid and pentarythritol,
for use as an additive in rosin inks, is the subject of
Japanese patent publication No. 73/18,332 June 5, 1973.
This is reported in Chemical Abstracts 80:97528r.
Experimental use has also been made of solution-
polymerized polymers of 97~ isobutyl methacrylate and 3% of
a methacrylate, these were not wholly satisfactory, because
solution-pclymerized polymers inherently have low molecular
weights, and are comparatively inefficient thickeners.
- CA 84:46321T discloses a gravure ink of a low Tg
alkane soluble acrylic resin and an alkane insoluble acrylic
resin.
Another reference of possible interest is U.S.
patent No. 2,803,611, concerned with an adhesive which
contains a blend of a copolymer of lauryl and hexyl meth-
- acrylates with limed rosin, a wax-naphthalene condensate
and a solvent, particularly a hydrocarbon solvent. These
higher methacrylic acid esters give very soft (Tg ~-5C)
polymers which normally cannot be produced as a powder. In
addition, they have a plasticizing effect upon the hard
binder and are not shown by the reference to have any
~$206~1
effect in thickening the composition, particularly so in
view of the fact that clay is included in the composition
to give thickening.
A Canadian patent application related to the present
application is that of Swift et al, Ser. No. 295,526,~ 4~2,1S'Q 'i
filed January 24, 1978; it
concerns lithographic inks in which the binder is a co-
polymer, having a ~n of 1,000 to 15,000, of up to 40~
isobornyl methacrylates (iBO~A) with, for example, isobutyl
msthacrylate and an unsaturated acid. The ink contains an
aliphatic hydrocarbon solvent.
Another patent con~erned with isobornyl meth-
acrylate is U.S. patent No. 3,485,775. It discloses
polymsrs containing 25-75% isobornyl methacrylate and
substantial amounts of msthyl methacrylate mers, which
detract from hydrocarbon solubility oE the polymer. Small
amounts of styrane, ethyl acrylate, or butyl acrylate are
permitted. Th~ di~closed molecular weight ran~e of the
polymers of t:~is reference i3 between lO,G30 to 2,0~0,000.
No unsaturated acid monomers are suggested.
U. S. Patent No. 3681,298 discloses polymers
h~ving a molscul~r weight range of l,000 to 8,500, con-
taining 40-60~ 13~bornyl metha_rylats and 40-60~ of methyl
methacrylate, ~tyrene, s-but~l m~thacrylate, or n-butyl
methacrylate, and up to 5~ 01 an unsaturat3d acid, and
the use of solvents compri~ing or consi~ting oL paraffins,
e.g~, octane. Amount~ of monomers 3u^h as methyl ~eth-
acrylate for such low molecular wsight polymer~ do not
appear to be particu'arly critical' thus abou' 50% meth~l
~o methacrylate is useful. In the present invention, in-
vo?vin~ high molecular weight pol~mers, ~uch qu~ntities of
. , .
.
methyl methacrylate would resu't in i~soluble polym~rs.
The pending Canadian application S.N. 295 ,526 and the latter two
patents are as3igned ~o ~he assignee of the instant
applicationO
Other acrylic copo'ym rs for ink3 are also
known, as sho~n for axampl3 in U.S. paLent No~ 3,764,587
(Zun'~er)0 The inhsrant viscosity of the polymer of the
latter patent, a measure of molecular wsight, is betwaen
0 2 and 0.35 msasured at 25C. using 25 milligram~ of
polymer in 5 cc. of chloroform, which suggest a Mw of
100,~00 or greaterO Tns monomers in the polymer are such
as would yield a very rubbsry, soft product, having a very
low calculated Tg as .efined herein.
The Aronof~ et al polymsr (U.S. Patsnt No.
3,271,3)l7), in one embodiment is primarily of vinyliden3
chloride, with acrylic acid, methacrylic acid, or itaconic
acid, an1 with the o~tion~l inclusion of othsr monomsrs.
The vinylldene chloride copolymers have molscul~r wsights
. in the range of 3,000 to 5,000. Arono~f et al also m3ntion
all-acrylic copolymers, ths invention being in the inclusion
of polyoxethylens ethers in m~terials su_h as inks. No
method of prep~ring the acrylic polymer is disclosed nor
are molecular weights. The specific acrylics disclosed
~ have extrsinely lo~ calculated Tg's. Aronoff et al disclose
25 - so'vsnts. including aliphatic hydrocarbons, aromatic hydro-
carbons, ketones, alcohols, etc.
- Hoshi et al U.S. patent No. ~,912,675 concerns
flexographic inks containing a filler, 5-35% by weight of
an acrylic resin, 5-20% of ons or more natural resins
30 selected from copal, dammar an~ shellac, and a solvent
~lZV641
containing at lea~t two of an aromati hydroc~rbon, an
al~ohol, an ester, and a glycol ethsr. The acryli~
polynsr allegedly has a molecular weight of 30,030-300,000J
a ~g of 20-105C., ~nd may be of isobutyl methacrylate
and methacrylic acid (raJios nol being given). Oddly, the
intrinsic vi~cosities given in the examp'es define polymers
having moLecul~r weights no higher than a few hundred --
no-~here near 30,000. One or the other appear3 to be in
error. At column 5, line3 35-50, the d-ynamic vi3cositigs
at 25C (n~ solvent specified) are given as 210-43v~ ce~ti-
poises for Examples 1-6 and 240-350 centipoises for
corn~rative Examples 1-5. Some of the copolymers are
impractical; in order to ge'~ a Tg of > 20 with lauryl
meth~crylate and acrylic acid at least 65~ acid would be
1~ needed. Such a polymer woull not be soluble in aliphatic
hydrocarbons, nor w3uld it be compatible with limed rosin.
U.S. patent No. 4,005,022 to Vijayendran dis-
closes a liquid toner, for developing electro3tatic images,
containin~ (A) 9-9~ parts of a saturated aliphatic hydro-
carbon having a Kauri-butanol number of 25-35, (B) 1-10
parts of an intsnsifier. The intensifier (B) contains (1)
1-10 parts soap, 80-97 parts aliphatic hydrocarbon, and
- (3) 3-20 parts of a concentrate. The c~ncentrate (3)
contains (a) 8-14 parts pigment, (b) 120-200 parts of an
acrylic or other polymer, (c) 1~0-240 parts saturated
hydrocarbon and (d) 0.03-6 parts pigment. The acrylic
polymer "Neocryl B-707!' ~ent~oned by Vijayendran ("a ter-
polymer compo~ed of vinyl toluene, i-butyl methacrylate
and lauryl or stearyl methacrylate") appears to be similar
to the acid-free isobutyl methacrylate-vinyl toluene co-
polJmers of Brown et al U.S. patent No. 3,417,041
* Trademark
'~ '
~,
(prepared by susp~nsion polymerization l~ing a chain
transfer agent to give a low molecul~r weight). The u~3ful
polymer3 had visco~itie~ in~-Varso ~o. 3 of from 37 to 1~0
centipoises. Similar waxy po'ymers made with higher alkyl
meth~crylates and ~cid~ are shown by Finn et al U.S. patent
No. 3,532,654 for floor polish emul3ions.
DETAILED DESCRIPTION OF THE I~ENTION:
According to the present invention, by utilizing
a relatively specific po'ym3r compo3ition, preferably
obtained by emulsion polymerization, followed by spray
drying, freeze drying, etc., a solid, high molecular
weigh highly efficient thickener for organic solvent
syste!ns, particularly aliphatic hydrocarbon solvents, is
obtained. Ths emulsion polymeriza.ion ~ives the desired
high molecular weight and the monomsr proportion3 an~ sel-
ection gives compatibility and efficient thicksning
pxop3rties.with ~olvent~ rich in aliphatic hydrocarbon~.
In particular the thickener~ ar~ efficient thickeners for
Lactol spirits (which is a trademark for solvent n~phtha,
an aliphatic "naphth~" which vaporizes in the toluene
evaporation range and is a blen~ of alipnatic hydrocarbons
and a minor amount of aro;natic hydrocarbon3) especially
when used in gravure inl~s containin~ metallated rosin as
a binder. Predominantly aliphatic hydro_arbon compositions
containing a high proportion o~ aromatic hydrocarbo~s such
as tolu3ne are also efficiently thickened by the compositions
of the invention. The thickeners of the invention are
efficient in thickening non-polar solvent systems containing
- other hydrocarbon3, such as toluene an~ other aromatics, as
well as for oLvher non-polar solvents for example perchloro-
ethylen3, and although effective, are les~ efficient
~.
B dTerraidveemdarfrforpeatnroalleiphatic hydr~carbOn sOlvent
"
~:064~
thickeners for sy3tems containing polar solvents, such as
oxy~;enated solvents including acetons, isopropanol, ethyl-
acetate, or ethylene glycol monobutyl ether. Preferably
ths solvent contains at least 50~, mora preferably at
least 70~, of a liquid alkane (sometimes referred to as
an aliphatic hydrocarbon).
In the drawing, the visco3ity profiles, on a
logarith:nic scale, versus solids content of copolymers of
isobutyl methacrylate and methacrylic acid con~aining
various amounts of acid, are sho~n to be co!nparable to
T-lO ethyl cellulose, a commonly used co;nmercial thickener.
The viscosities in centipoises of the conpositions were
determined by measuring th3 visco3ity of a 15~ solution of
the polymer in toluene and then diluting to 10%, 7.5~, and
5% with Lactol spirits. The viscosity profile is compared
to a reference curve for T-lO ethyl cellulose.
Gravure ink vehicles are known which are based
on metallated rosin resins rnodified with T-10 g*rade ethyl
cellulose or by ethylhydroxyethyl cellulose, as has been
noted hQretofore. These inks are colnmonly used in high
volums publication ~ravure printing of Sunday newspaper
supplements, quality magazines, and mail order catalogues.
The thickeners of the invention nave viscosity profiles
quite si~ilar to "T-lO"*ethyl celluloss (sold by Hercules,
Inc.), and are co~patible with metallated rosin, e.g.,
limed ro3in binders, maleated rosin, etc. The conventionally
used ethyl cellulose as well as the thic~eners of the in-
vention have the advantages of being soluble in non-polar
solvents such as a blend of Lactol spirits and toluen3 in
~o the ratios of 92:8. The high viscosity provided by the
thickeners at a low solids content of the thickener in the
; .
* Trademark - 8 -
solvent, o~ between about l~ and 15~ solids o~ ths
thickeners on tota~ composition, gives co~patibility with
metallated rosins such as limed rosin, and contributes to
hold-out, gloss, adhesion, and rub and scratch resistance
to the ink film. In place of limed rosin, other conven-
tion31 ink binders are useful, inclu~ing rosin metallated
-with other polyvalent metal conpounds, maleated rosin and
other rosin esters, terpene resins, and ths like. The
weight ratios of resinous binder:solvent:thickener are
between O and ~0 parts binder,preferably at least l part
binder:4 and 100 parts solvent: l part thickener, by weig'nt.
Usu~lly, in an ink at least 1 part binder per 1 part of
thickener is used. Preferably the ratios are 5-35 binler:
5-80 solvent: 1 thickener. The total thicksner comprises
50~-10~% of the addition polymerized thickener of the
invsntion, optionally with ~50~ of the prior art thickeners
ethyl cellulose an~/or ethy] hydroxyethyl cellulose.
Ths amoun' of dye or pigment is varied as needed. Other
conventional additives may be used.
The thickener i5 an addition polymer of ethyl-
enically unsaturated (A) hydrophobic monomers being within
: the hydrogen bon~ing class (defined hereinbelow) of from
moderate to poor and (B) hydrophilic mono~ers being in the
strong hydrogen bonding class in a ratio of between 90 (A):
10 (B) and 99.9 (A):O.l (B), at least about 60% of the
those who3e homopolymer3 have
hydrophobic monomer(s) (A) are ~ a solubility parameter
of ~ 8.8, any oth~r hydrophobic monomer(s) being such as to
not destroy the organic solvsnt solubility of the thickener
polymer. The hydrophilic mononer(s) (B) preferably compriss
3 at least a predoninant proportion of monomers containing
at least one of a.carboxylic acid group and a sulfonic
_ g _
.~ ,
r -
~206~
acid group, although other hydrophilic monomers are useful.
Preferably the hydrophobic monomer is selested
from at least one of a C~-C20 straight or branched chain
alkyl or cycloalkyl ester of methacrylic acid or
p~oviding homopolymers
acrylic acid, each/having a solubility parameter of ~8.8,
hydrophobic
styrene and vinyl toluene. Particularly preferred/monomers
(A) are ~inyl boluene and ~tyrene and especially those whose
polymers have
hom~ a solubility parameter of ~8.8 selected from
. _-butyl methacrylate,
s-butyl methacrylate,
t-butyl methacrylate,
t-butyl acrylate,
i-bornyl methacrylate
i-bornyl acrylate,
_-propyl methacrylate,
dicyclopentenyl methacrylate,
- dicyclopentenyl acrylate.
Most highly preferred is i_butyl methacrylate.
Preferably the hydrophilic monomer is selected
from acrylic acid, methacrylic acid, itaconic acid, and
vinyl sulfonic acid. Methacrylic acid is most highly
preferred, ône reason being its particularly high
efficiency in this use; for example, the acrylic and
analog i9 much~less efficient. The unsaturated carboxylic
acid may be a simple monocarboxylic acid, a polycarboxylic
acid, or may be a partial ester or half amide of such a,~-
unsaturated polycarboxylic acids, and salts thereof with
a volatile base such as ammonia, or with a volatile water-
soluble amine such as dimethylamine, triethylamine, tri-
~0 ethanolamine, morpholine, N-methyl morpholine, picoline,
-- 1 0
1~
and the like. ExampLes of copolymerizable ethylenically
` unsaturated monocarboxylic or polyca.rboxylic acids are sorbic,
: acryloxyacetic, acryloxypropionic. cLnnamic, vinyl furoic,
a-chlorosorbic, methacryloxypropionic, methacryloxyacetic,; 5 p-vinylbenzoic, acrylic, methacrylic, maleic, fumaric,
~ aconitic, atropic, crotonic, and itaconic acid, or mixtures.~. thereof, with itaconic acid and the ~-~-unsaturated mono-
f. carboxy.ic acids, particularly methacrylic acid an~ acrylicacid, being preferred. Other copolym~rizab~e acid monomers
include the alkyl half esters or partial esters of unsat-
urated polycarboxylic acids such as of itaconic acid, maleic
acid, and fumaric acid~ or th3 partial amides thereof with
C2-C4 amines. Preferred half esters ara th3 lower alkyL
. (Cl to C8) esters such as methyl acid itaconate, butyl aciditaconate, methyl acid funarate, butyl acid fumarate, methyl
acid maleate, and butyl acid maleate. Such partial esters
~` and partial amides are considered to be "a-~-unsaturated
monocarboxylic acids," and the term as used herein includes
such esters and amides. Typical hydrophilic monomers, in
addition to or even in place of those containing a sulfonic
acid or -COOH group, are one or more of the ethylenically
unsaturated acrylamides or hydroxyacry'.amides,including
acrylamide, methacrylamide, methylolacrylamide, methyloL-
methacrylainide, hydroxyethyl acrylate, hydroxyethyl meth-
acrylate, hydroxypropyl methacrylate, and hydroxypropyl
acrylate.
The novel preferrsd dried emulsion copolymer
of the invention is at least predominantly of l) isobutyl
methacrylate an1 2) at least on3 acid selected froln the
group ^onsisting of acrylic acid, msthacrylic acid and
itaconic acid in the weight ratios of 1):2) of between
99.9:0.1 and gO:lO, preferabLy in a ratio between about
99.5:0.5 and 96:4 and still more preferably in a ratio
between about 99.5:0.5 an~ 97.5:2.5. As noted e1sewhsre
-- 11 --
herein, ths preferred acid is methacrylic acid. Conventional
emulsion polymerization is utilized and the resulting latex
is processed to recover a dry solid material soluble in the
organic solvent.
The viscosity of a solution of the thickener
at a concentration of 15~ in toluene ranges from about ~00
to about 200,000 cps. preferably from about 500 to about
75,000 cps., more preferably about from about 750 to 10,000
cps. The weight average molecular weight (Mw) of the
thickener, ~s determined by gel permeation chromatography
using polymethylmethacrylate for calibration, is between
about 100,000 and 2,000,000, preferably 200,000 to 2,000,000
and more preferably ~00,000 to 1,500,000. While high
temperature solution polymerization cannot be utilized to
prepare the polymers of the invention because low molecular
weight polymers are produced, other useful routes, less
preferred than emulsion polymerization, are bulk polymer-
ization and suspension polymerization.
The molecular weight of typical thickener
polymers, determined by gel permeation chromatography
(G.P.C.) is of the order of ~w = lx106 + 0.5 x 106. Com-
parison of G.P.C. molecular weight and solution viscosity
(15% in toluene) of typical replacements for T-10 ethyl
cellulose (98~ i~/2~ MAA) is as follows:
~w x 106 ~n x 105 Viscosity - cps.
(15~ in toluene)
1.02 2.6 1600
1.24 2.4 4800
1.40 2.25 4500
~0 As noted above, the preferred concentration of
unsaturated acid in the polymer is between 0.5~ and 2.5~.
- 12 -
1 ~ ~ 6~ 1
One reason for this is that at the lower solids contents in
the Lactol spirits~toluene solvent noted above, below about
5 or 6~ solids, the higher acid content materials become
less compatible. Another reason the acid level is found
to be critical is that at higher acid levels, the thickener
becomes less compatible with non-polar solvents and with
limed rosin.
The metallated rosin binder or other resinous
binde~ useful in the invention are well known in the ink
industry as shown by the art cited above, and further des-
cription thereof is not considered necessary in the present
instance. Also well known are pigments, dyes and other
conventional additives for inks, particularly solvent-based
gravure inks.
The copolymer of the thickener is preferably
made by the emulsion copolymerization of the several monomers
in the proper proportions. Conventional emulsion polymer-
ization techniques are described in United States patents
2,75~,280 and 2,795,564. Thus, the monomers may be emul-
sified with an anionic, a cationic, or a nonionic disper-
sing agent, about 0.1~ to lO~ thereof being used on the
weight of total monomers. When water-soluble monomers are
used, the dispersing agent serves to emulsify the other
monomers. A polymerization initiator of the free radical
type, such as ammonium or potassium persulfate, t-butyl
hydroperoxide, cumene hydroperoxide, etc. may be used alone
or in conjunction with an accelerator, such as potassium
metabisulfite, or sodium thiosulfite. The initiator and
accelerator, commonly referred to as catalyst, may be used
in proportions of l/2 to 2~, each based on the weight of
monomers to be copolymerized. The polymerization
- 13 -
temperature may be from room temperature to 90C or more as
is conventional. This polymsr ;s esssntially uncrosslinl~sl.
Examples of emulsifiers or soaps suited to the
polymerization process of the present invention include
alkali metal and ammonium salts of alkyl, aryl, alkaryl,
and aralkyl sulfonates, sulfates, and polyether ~ulfates/
ethoxylated fatty acids, esters, alcohols, amines, amides
and alkyl phenols; and complex organo-phosphoric acids,
and their alkali metal and ammonium salts.
One way of describing and defining the monomers
of this invention is by use of the solubility parameter
concept. "Polymer Handbook", 2nd Edition, J. Brandrup
and E. H. Immergut, editors (John Wiley and Sons, New York
1975) Section IV Part 15 entitled "Solubility Parameter
Values" by H. Burrell, on pages IV-337 to IV-368,
defines solubility parameter,
: describes how it is determined or calculated, contains
tables of solubility parameters and gives further references
to the scientific literature on solubility parameters.
The solubility parameter is the square root of the cohesive
energy density which in turn is the numerical value of the
potential energy of 1 cc. of material, the potential
resulting from the van der Waals attraction forces between
the molecule~ in a liquid or solid. Burrell describes a
number of wayq of calculating solubility parameters from
experimentally determined physical constants and two ways
of calculating them from the structural formula of a
molecule. The structural formula methods are normally
used when the data for the calculation from physical con-
stants are not available or are c-,nsidered particularly
unreliable. Calculation from the structural fornula
- 14 -
B
'~ ~12V6~1
utilizes tables of group molar attraction constants such
as those given on page IV-339 of the Handbook. The table
of Small is preferred. See also J. L. Gardon, J. Paint
Technology, 38, 43 (1966), and "Cohesive Energy Density"
in "Encyclopedia of Poly. Sci. & Tech" H. Mark et al,
editors.
The solubility parameter concept may be con-
sidered an extension of the old rule "like dissolves like"
recognized from the early days of chemistry. A noncross-
linked polymer will normally dissolve in a solvent of
similar solubility parameter and a crosslinked polymer will
normally be swollen by a solvent of similar solubility
parameter. Conversely, solvents with solubility pa ameters
far from those of the polymers will neither dissolve nor
swell the polymer. As given by Burrell the solubility
parameter of polymers may be determined, among other ways,
by measuring the swelling of the polymer in a series of
solvents. Solubility parameter for polymers may also be
estimated by calculation from the group molar attraction
constants as mentioned above. In the usual situation, it
is found that solvents with a range of solubility parameters
around that of the polymer will dissolve the uncrosslinked
polymer. Those skilled in the art have added the further-
refinement of classifying solvents as poorly, moderately
and strongly hydrogen bonded solvents used to dissolve a
large number o~ polymers. In Iable 5 starting on page
IV-345, there is given solubility parameters of a number
of polymers determined by calculation and by other methods.
The following table contains a list of monomers
~o along with values (where the values were in readily avail-
able sources) of their solubility parameters, the solubility
- 15 -
~2~6~
parameter of homopolymers of given monomers, and the
hydrogen bonding class appropriate for the monomer. The
solubility parameter values and hydrogen bonding class of
most of these monomers are those given in Table 1 cf
Burrell. Values for monomers not in Burrell's table are
determined or computed following the teachings in Burrell~s
writings v.s. Dimensions for the solubility parameters
given in the table are the usual ones, square root of
(calories per cubic centimeter). The hydrogen bonding
class strong, moderate or poor is ascertained by using the
method of C. M. Hansen, Journal of Paint Technology, Vol.
39, p . 104-117 and 505-514 (1967) .
High MW
Monom~r-~ Homopolymer*Hydrogen Homo-
Solubility Solubility Bonding Polymer
Monomer Parameter Parameter- Class T C Abbre
_g
Acrolein 9. 8 -- S-- Acr.
Acrylamide --- -- --165 A~
Acrylic Acid12.0 -- S~100 AA
Acrylonitrile 10. 5 13 __ 106 AN
o-Bromostyrene 9.8 -- P~- BrSt
1,3-Butadiene 7. 8 8. 2 P~ -44 Bd
i-Bornyl meth-
~ acrylate --- 8.2 --144 i_BOMA
i-Bornyl acrylate--- 8.2 --94 i_BOA
i_Butyl acrylate 8.5 8.7 M-24 i`-BA
n-Butyl acrylate 8.6 9.0 M-56 BA
t-Butyl acrylate --- 8.7 ---22 t-BA
n-ButyL meth-
acrylate 8.2 8.8 M22 BMA
i-Butyl meth-
acrylate --- 8.6 --48 _-BMA
s-Butyl meth-
~ acrylate --- 8.7 --60 s-BMA
- 16 -
~1206~1
High MW
Monomer* Homopolymer*Hydrogen Homo-
Solubility Solubility Bonding Polymer
MonomerParameter Parameter Class T C Abbre.
t-Butyl meth-
~ acrylate --- 8.6 -- 107 t-BMA
t-Butylaminoethyl
methacrylate --- -- -- 33 t-BAEMA
o-Chlorostyrene 9.6 -- P 119 ClSt'
Cyclohexyl meth-
acrylate --- -- -- 66 CHMA
_-Decyl acrylate 8.2 -- M -- i-DA
Dicyclopentenyl
methacrylate ~ - -- -- DCPMA
Dimethylamino ethyl
methacrylate 7.0 -- S -- DMAEMA
Ethyl acrylate 9.6 9.4 M -22 EA
Ethyl meth-
acrylate 8.~ 9.0 -- 65 EMA
Dihydroxypropyl
methacrylate 9.0 -- S -- DHPMA
- Ethylhexyl
acrylate 7.8 __ M v~-70 EHA
Fumaric acid --- -- S -- Fu~A
Fumaric half esters
and half amides --- -- S
l-Hexene 7.4 -- P -- hex
2-Hydroxyethyl
methacrylate 8.0 __ S 55 HEMA
! 30Hydroxypropyl
methacrylate --- -- S 73 HPMA
Isoprene 7.4 -- p _7~ Ipn
Isopropyl meth-
acrylate --- 8.8 -- 81 i-PMA
35ItacGnic acid --- -- S -- IA
Maleic anhydride 13.6 -- S -- MAn
Maleic anhydride half
esters and half
amides --- -- S -- --
-17-
L
High MW
Monomer* Homopolymer*Hydrogen Homo-
Solubility Solubility Bonding Polymer
MonomerParameter Parameter Clas3 T C AbbreO
g
Methacrylic acid 11.2 -- S ~ 106 MAA
Methyl acrylate 8.910.1 M 9 MA
Methyl methacrylate 8.9 9.3 M 105 M~A
Methylolacrylamide --- -- S -- MOA-100
~ - Methylstyrene 8.5 -- P 155 MeSt
Phenyl methacrylate -~ M ~ 105 PhMA
n-Propyl meth-
- acrylate --- 8.8 -- 35 n-PMA
Styrene 9.3 -- P 100 St
Tetradecyl acrylate --- -- -- 20 TDA
Vinyl acetate 9.0 9.4 M 3Q VAc
Vinyl chloride 7.8 9.7 M 82 VCl
Vinyl sulfonic acid --- -- S -- VS acid
Vinyl toluene 9.1 -- P -- VTol
*K. L. Hoy, J. Paint Technology 42, 76-118 (1970)
and other sources.
S - Strong P = Poor M = Moderate
The thickener polymers of the invention are sol-
uble in C6-C10 normal alkanes at 20-25C; such solubiLity is
meant wherever reference is made to solubility in aliphatic
hydrocarbons. The solubility parameters of homopolymers of
the main proportions o~ the monomers used are ~ 8.8, of course
with the proviso that the monomer identity and quantities
thereof are such as to not prevent solubility of the thickener
in aliphatic hydrocarbons. For example, substantial quan-
3 tities of methyl methacrylate are not used for the reason
that, although the solubi1ity parameter of the monomer is
about 8.8 and the hydrogen bonding class is medium, the
homopolymer solubility parameter of this monomer is about
9.3 and in copolymers it may adversely
- 18 -
~2~
affect solubiLity of the polymeric thickener in aliphatic
hydrocarbon solvents.
The Tg of the polymeric thickener is ~0C,
preferably ~40C. As a practical limit, 100C. may be
attained.
Molecular weight i~ determined by gel permeat-
ion chromatography, utilizing polymethylmethacrylate for
calibrationr further details being given below.
Second order transition temperature or glass
transition temperature (Tg) is the temperature at which the
polymer changes from a glassy state to a rubbery state,
calculated as noted above. The calculated Tg of the
polymer is determined by calculation based upon the Tg of
homopolymers of individual monomers as described by Fox,
Bull. Am. PhysicalSoc. 1, ~, page 123 (1956). Tables of
the Tg of homopolymers are given in ~'Polymer Handboo~"
Section III, Part 2 by W. A. Lee and R. A. Rutherford.
~f course, the actual Tg may be measured by known methods.
In drying the latex to give a particulate product,
any suitable method may be used, preferably involving spray-
drying, but freeze-drying or other methods may also be used.
If bulk or suspension polymerization is used, suitable
grinding means are used to produce granules or powders.
A gravure ink formulation useful with thickener
polymers of the following examples is:
Nonvolat les Volatiles
TiO2 (R-900 grade) 21.7 21.7 ~~
Limed rosin vehicle (60~
solids in Lactol spirits) 45.7 27.4 18.3
30Lactol spirits 21-7 ~~ 21.7
Thickener polymer (15~
solids in toluene) 10.9 1.6 9.3
- 100.0 50.7 49.
-- 19 --
llZ(~41
This formulation may ~erve as a substitute for
conventional Type A and Type B gravure publication inks,
which are suitably formulated as follows:
Type A Type B
Material pbw pbw ~aterial pbw
Pigment (organic type) 7 10 Pigment (inorganic type;
e.g., TiO2) 3
Pigment extender (e.g.,
limestone or clay) 20 10
, Limed rosin 38
Limed rosin 20 20
Lactol spir1ts si 40 Lactol spirits 30
Ethyl cellulo~e2 3 Ethyl hydroxyethyl
cellulose 2
Toluene 0 17
- -- -- 100
100 100
Similar typical formulations are given in the
publication "Printing Ink, A Multiclient Market Survey"
Hull & Co., 77 Randfield Road, Bronxville, N.Y. 10708,
Augu~t 1973.
A Type A gravure ink formula i~ given in
which 30 parts of limed rosin containing small amounts of
wax and plasticizer are blended with 15 parts pigment and
clay, containing for example 4-8% organic pigment or about
10% black pigment, with 55 part~ aliphatics such as 1actol
spirits or heptane. The solvent typically contains appre-
ciable amounts of aromatic solvents as impurities. Such a
formulation is as shipped to the printer, who may add up to
1 part of additional solvent for each part of ink.
A practical test for suitability as a thickener
for solvent sy~tem~, including gravure inks, is one in
which the pigment is omitted, as in the examples herein
below.
A procedure for preparing an emulsion polymer
useful in the invention is as fallows:
_ 20 -
., ,
Substance _ Parts by Weight
Water 60.33
Surfactant (sodium lauryl sulfate) 0.02
IBMA (isobutyl methacrylate)38.71
MAA (methacrylic acid) 0.79
Sodium dithionite 0.02
Ammonium persulf'ate 0.13
100 . 00
Procedure:
1. Charge about 50 parts of the water to
stirred reaction flas~: and heat contents.
,
- ~ 2. Prepare monomer emulsion in separate vessel
as listed below:
a. Charge remaining water
b. Add surfactant
c. Mix the monomer (98 iBMA/2 MAA) into
the surfactant solution
d. Stir well to form a stable monomeric
emulsion.
3. Gradually add emulsion to the reactor and
initiate polymerization at 80-85C. using
peroxy disulfate. Maintain temperature at
80-85C. until all of the monomer has been
added.
4. Hold at 80-85C. for 30 minutes.
5~ Cool the batch and pack.
Properties:
Total Solids: 40-42%
pH : 2-5
A similar procedure noted in the examples, using
.
-- 21 --
.! .
using sodium dodecyl benzene sulfonate in place of sodium
lauryl sulfate is also useful. It may be important from
-~ an odor standpoint to eliminate residual monomer as nearly
as possible. This may be accomplished by means of reduced
i 5 pressure, introducing additional initiator at the end of
the reaction, adsorption of monomer by solid adsorbents,
',3 etc. Total solids content may be from about 30~ to 50~ or
more. Particle size is not critical and may be from 0.05
.,
to 1 in the usual case. The resulting latex is spray dried
~; 10 or freeze dried, preferably spray dried, to a powder. The
latex usually has an acid pH as made, but may be neutralized
or made alkaline with conventional bases, including ammonia,
amines, etc. but this is not necessaryO For instance, the
latex of Example 9 was neutralized with ammonia before
drying whereas the others were not.
To determine compatibility of the thickener
~3 with limed rosin and solvent, the test method utilized is
to determine the solution clarity and dried film clarity
initially, and after 24 hours at room temperature, of
~ 20 solutions made up as follows:
{~ Solution Nonvolatiles
Thickener (45~ in toluene) 8 g 3.6 g
!''Limed rosin (60~ in lactol spirits) 43 g 2508 g~
Hexane/heptane 1/1 by weight 490 g 0.0 g
r
, .
- 22 -
:;
~ '
As soLvents for the thickeners of the invention,
suitable aliphatic hydrocarbons (alkanes), which are the
`~ preferred solvents, include ligroine (benzine, petroleum
ether, coal tar light oil, petroleum naphtha), cycloalkanes
such as cyclohexane and ethylcyclohexane, C5-C10 alkanes,
etc., generally b~iling in the range of ~0C-175C. These
!~ "weak" solvents are those which are conventional in the
~ printing ink industry.
:s
Strong aromatic solvents such as
xylene, benzene and toluene are not normally used in the
present invention in quantities greater than about 10~ of
the total solvent being thickened. The term "aliphatic
hydrocarbon solvent" as used herein permits of the inclusion
of such small amounts of aromatics. In some cases, a small
proportion of a solvent such as toluene is inherently
present in the aliphatic hydrocarbon as an impurity or may be
- deliberately added. For example, some "aliphatic" hydro-
~ carbons contain an aromatic impurity. Such strong solvents
`i 20 are sometimes necessary, as in the case of "T-10" ethyl
cellulose, which is not soluble in pure lactol spirits
in the absence of small amounts of toluene. Of course,
the thickener must be compatible with the binder as well as
the solvent.
As may be noted from the following examples, the
polymerization conditions, and those conditions in relation
! .
to proportions of monomers, are important in obtaining
products having usable viscosities. Comparative Example
B used a chain terminator which gave a low molecu'ar
~0 weight polymer as did Examples C and D. One distinction
between comparative Example F and Example 1 is in the
- 2~ _
..
` ` ~
'` 112()64~
leve' of acid. A~ may be noted, the criteria for a
u~eful product includs the vi~co~ity and molecular weight,
~olvent an~ binder compatibility, etc. Ths fol~owing Table
I give~ the polymerization variable~ and monomer variable~
of example~ in accordance with the invention, and com-
parative example~ o~ material~ out~ide of the invention.
_ _ .. _ .. _ . . . .. . .. . ...
t
~ .
,
112
o
~ o ~, o o ~ ~ ~ o
;i o
E~ o o I I,, ,, I Io
~ ~\
~13
o ~ ~ cu o o u~ O r~ o o
~Q o ~ o o o o o o o o o
. ~
.~ o ~ oo o ~ o ~ o o o o
O ~ ~ ~ C~ ~ ~ ~ C~l
o
O o
~3 C) ~4 o o o o o o o o o o
m ~ ~. o~ co co ~
E¢~ ~E~
~ o~ oO 0
O ~ ~ O ~
o o
~3 a~a~ o ~a~
~ ~ m 5~
.~ ~ O ~ ~ g ~ O
H~1 ~ O~ O ~O
. . ~,~ C ~ O ~ -
0 0~O~c ~ O O 00~,~ 0 ¢ O ~0 0
m 0~
0~ ~ ~ ~¢ ~ O
8 o ~ mv~ ~o
o o ~ ~ ~ co oo o~ c~ ~ c~
~ ~ c~ ~ ~ oo ~ O ,~
x
Ll~ O Ll~ O
- 25 --
3~12~)6~ `
~o
1 o E ~ E ~C , E E E
~, C) ~ ~ ~ o
~ o a) a) a) ~ i o a
:` ~ ~ ~
~0
i; P~
' E~ I O O O ~ I u~
V ~ ~ ~ ~ I
o ~
C~ .
.i ~ ~ ~ ~ r~
C) O O O L~ i o o o
. ~ . . . .
O O O O O O O
D~
U~
., ~ s~
.~ ~ O O O O O O O ~
0 ~ ~ ~ rt~ ~ ~ ~ ¢
., a~
:. ~ .
~V
.,, . l l
O OO ~ O O 0~1 -
E oo 0000 L~ c~ co 00 D7
~E~
0~ ~
~ O j ,~
o ~
c~P~ ~ ~ P~ td a) 0
r~ ~ ~ ~ V O ~
~ ~ ; ~ O I td
rl ~ O ~ I ~ ~ ~
H H ~ E O ' N CU C~l O bO
O O O 0~ o~ om o~
cC I ~ ~ ¢
~ ~ ~ ~ ~ 'C ~ cC
~ ~ ~ ~ ~ ~ ~ ~ o ~ o~
o c~
~1 \\ \ ~ \ ~ \ \ ~ EO
E ~m; I ~ ~ m
.~ r~ ~0 a
O 0~~ ~D ~ ~ I ~ ~ c~
~ ~ ~ o~ ~ ~ , ~ ~ ~ ~ ~o ~
~ ~ ~ o ~ O
~ ~ l ~
E C~l ~ ~ ~ ! ~ ~ ~
~ v ¢ m v ~ o i~
I ~ o U~
_ 26 --
t.~
~L~,Z~
AA: acrylic acid
n-BA: normal butyl acrylate
iBMA: isobutyl methacrylate
~` n-BMA: normal butyl methacrylate
MAA: methacrylic acid
~ NaBS: sodium bisulfite
} NaPS: sodium persulfate
NH4PS: ammonium persulfate
BTM: bistribromomethane
Lykopon: sodium dithionite
- FormQpon: sodium formaldehyde sulfoxylate
t-B~P: tertiary butyl hydroperoxide
DIBHP: diisobutyl hydroperoxide
St: styrene
~ 15 CHP: cumene hydroperoxide
~ NOTE: Examples B, C, and D had imPractiall~ low
-
~ viscosities. As is known, the quantity of
initiator, po~ymerization temperature and
method, chain transfer agent, etc., influence
molecular weight.
.- The viscosity properties of the polymers in
solvent and of the formulated inks are given in table II.
In all cases the molecular weights (~w) of the addition-
polymerized-polymeric thickeners of the invéntion as
determined by gel permeation chromatography, are within the
range of 100,000-2,000,000, and for the most part are
within the range ~00,000-1,500,000. The products of the
Comparative Examples are outside of these ranges or are
unsatisfactory for other reasons.
,
- 27 -
;,
* a~
~ o ~
i' bOO
~;
~ ~ *
~ u~ ~ o ~ L~ o o ~
:`?
,~
.
. a) ~ c~
H a:~ H ~ .
:` H .
;. ~ ~ ~ ~ O O
i" ~E~
.
.' *~ LS~
~ O ~ 1~ CS~ O C~J 1~ i I I I I I I I
O ~ ~1
~ I .
.' *
~ . U~ O
U~ o o o o
c) ~ r~ O L(~ O LO
* ~ ~ CU C~J ~ oo o ~
o ~ C~ ~
~ ~ l o o L~ o o o o o o o o o o o
~ D~ L~ U~ ~ O O O O C~ O O O O O O
* ~ F~ C~ ~ N 1~ ~ O ~ ~D O i~ O C~ O O
~r~ ?~ .
L~ O ~ ~ 1~\ ~ ~1 0 -=t O ~U ~ O C~
~E~ ~ r
., ~ ~
~ ~ ~ C~ X~ 0 ~ ?~
~i
O I ~\
u~ - 28 -
llza~
\bO ~ 1.
~ L~
~o~ ~
c ~ ~
~ L o
~ a) 0~
~ ~ o
P; ~
~ a)
~ O C~ ~ I
~0 .
.~ ~_ C~
. ~
C~ ~ bO
~I) ~ C)
~ $
a
s~ ^
~0 C)
C) ~ ~ ~
s~ ~
o~ ~0
E~
o~ ~
o ~i ~;
~ ~ ~- o ~- o ~ ~
~: C) * 0 LO ~ ~ ~ U
~* ~ ~0 ~o ~ ~o P" ~ ~
* rJ~ ~ ~ r~ N ~ N ~1
P. ~'f O N ~q ~ . ~1
0~ C) ~ O ~ O o O 1~5
a) ~ ~ 0~1 0 ~ O
r. ~ ~ E~! o g~ o ~ ~ =
* ~ P~ ~ O ~ O
~o o ~ O 11 * .Y
rl ~ O
~1 ~ ~ C~ ,
~ ~ 0 ~ o Lr ~ 5~
~ æ I ~ ~*
L(~ o rl
I
- 29 - I
B
~Z~6fll
Gel perm~ation chromatogram~ for use in e~tima-
ting molecuLar weights are run on squipment co~mercially
~- marketed by Water3 Associates of Marlboro, Mas3. !'Styragel" *
column~ are availab e p~epacked in a variety of poro3ites.
A column set i~ normally compo~ed of four or five four-foot
(1.22 m) section~ cho~en to cover the molecular weight range
i. to be mea~ured. With column ~ets o~ thi~ length sufficient
-~ resolution is obtained 90 that axial di~per3ion can bs dis-
s regarded. The colu~n ~et mu~t be calibrated for ths polymsr
typ9 the molecular weight of which is to be determined.
Narrow molecular weight 3tandards are availabLe for p~'y-
~tyrene. Calibration curve~ for othar polymers ~uch as
polymethyl methacrylate are con~tructed from the chromato-
grams of broad ~amples u ing either an approximate distri-
bution techniq~eL or a universal calibration curve technique2.
~i To calcu'ate the molecular weights of unknown samples a
table i~ prepared of the value Wi, of ths GPC curve above
bassline at equal volume incremsnts and the molecular
weight Mi, read from the calibration curva at thsse volumes.
Ths weight average molec~lar weight ~w, and the number
average molecuLar weight Mn, can be calculated from the~s
valuss with the equation~
~w = ~WiMi ~n = Wi
Wi ~-- ~Wih~i '
. ~ Wi = 1
;,~ 25 It i9 to be realized that the molecular weight number~
given are approximate and not precise, but are valid'y used
for comparative purpo~es, particularly with polymers of
~imilar compo~ition~, and u~ing the same ca'ibration
~tandard.
- 3 -
' * Trademark
~
2~ 6 ~1
Calibration of Gel-Permeation Column with Unfractionated
Po(ymers, A. Weiss9 E. Ginsberg, J. Poly, Sci., Pt.-A-2,
- 2
A note on the Universal Calibration Curve ~or Gel Permea-
tion Chromatogra~hy - A Weiss, E. Ginsberg Poly Letters
~\ Unless otherwi~e stated, all parts and per- .
. centages given herein are by weight.
s:
~ ,
.
.~, .
`
