Organophilic clay modified with silane compounds

Organophilic clays useful for modifying the rheological properties of organic fluids are made from a smectite type clay, a quaternary ammonium compound and an organosilane.

BACKGROUND OF THE INVENTION 
The field of art to which this invention pertains is organophilic modified 
clays. 
Organophilic clays which are compatible with organic liquids have been 
known for some time. Their preparation and various uses have been 
described in, for example, U.S. Pat. No. 2,531,427 and U.S. Pat. No. 
2,966,506. As taught by these references, naturally occurring water 
dispersible clays, such as montmorillonite, are reacted with "onium" 
compounds to produce organic clay complexes which are compatible with 
organic liquids. 
In order to obtain maximum dispersibility and maximum thickening or gelling 
efficiency using organophilic clays, it has been necessary to add a low 
molecular weight polar organic compound to the composition. Such polar 
organic compounds have been called polar activators dispersants, 
dispersion aids, solvating agents, and the like. Methanol is an example of 
a useful polar compound. 
Organophilic clays which are said to have enhanced dispersibility in 
organic systems without using a polar activator are described in U.S. Pat. 
No. 4,105,578. Such organophilic clays are made from the reaction of 
smectite-type clays with a methyl benzyl dialkyl ammonium compound wherein 
the alkyl groups contain at least 16 carbon atoms. 
Other organophilic clays having enhanced dispersibility in organic systems 
are described in U.S. Pat. No. 4,412,018. These compositions are made by 
reacting a smectite-type clay with an organic anion, such as an organic 
acid, and an organic cation, such as a quaternary ammonium compound. 
Additional organophilic clays are described in U.S. Pat. Nos. 4,434,075, 
4,434,076, and 4,450,095. 
SUMMARY OF THE INVENTION 
This invention is directed to easily dispersible organophilic clays made by 
modifying a smectite-type clay with a quaternary ammonium compound and an 
organosilane. 
The compositions of this invention are the reaction products of a smectite 
type clay having a cation exchange capacity of at least about 75 
milliequivalents per 100 grams of clay and (A) a quanternary ammonium 
compound having the structure: 
##STR1## 
wherein R.sub.1 is an alkyl group having about 12 to about 22 carbon 
atoms, wherein R.sub.2, R.sub.3 and R.sub.4 are alkyl groups containing 1 
to about 22 carbon atoms, aryl groups and arylalkyl groups containing 7 to 
about 22 carbon atoms and wherein M is chloride, bromide, iodide, nitrite, 
hydroxide, nitrate, sulfate or C.sub.1 to C.sub.18 carboxylate, further 
modified with (B) an organosilane compound having the structure: 
EQU R.sub.n Si X.sub.(4-n) 
wherein n is an integer of 1 to 3, wherein R is an organic radical having a 
carbon atom directly linked to the silicon atom and wherein X is alkoxy, 
acryloxy, amino or halogen. The organic radical contains from 1 to about 
20 carbon atoms and can be alkyl, aryl, alkaryl, arylalkyl, vinyl, allyl, 
aminoalkyl, aminoaryl, and organic radicals which contain ether, ketone, 
ester and carboxyl groups. The compositions of this invention contain 
about 50 to about 150 milliequivalents (meqs.) of the quaternary ammonium 
compound (A) and about 0.5 to about 5 weight percent organosilane, said 
meqs being based on 100 grams of clay (active basis) and said weight 
percents being based on the weight of the organophilic clay, i.e., the 
theoretical weight of the reaction product of the clay and the quaternary 
ammonium compound. 
DESCRIPTION OF THE INVENTION 
The clays used to prepare the composition of this invention are 
smectite-type clays which have a cation exchange capacity of at least 75 
milliequivalents per 100 grams of clay. Particularly desirable types of 
clays are the naturally occurring Wyoming varieties of swelling bentonites 
and like clays, and hectorite, a swelling magnesium-lithium silicate clay. 
The clays, especially the bentonite type clays, are preferably converted to 
the sodium form if they are not already in this form. This can be done by 
preparing an aqueous clay slurry and passing the slurry through a bed of 
cation exchange resin in the sodium form. Alternatively, the clay can be 
mixed with water and a soluble sodium compound, such as sodium carbonate, 
sodium hyroxide and the like, followed by shearing the mixture with a pug 
mill or extruder. 
The quaternary ammonium compounds used in this invention contain at least 
one alkyl substituent on the nitrogen atom having at least 12 carbon atoms 
up to about 22 carbon atoms. The other nitrogen substituents are (a) 
linear or branched alkyl groups having 1 to about 22 carbon atoms, (b) 
arylalkyl groups, such as benzyl and substituted benzyl and (c) aryl 
groups, such as phenyl and substituted phenyl. The quaternary ammonium 
compounds can be represented by the structural formula: 
##STR2## 
wherein M is an anion, such as chloride, bromide, iodide, nitrite, 
nitrate, sulfate, hydroxide, C.sub.1 to C.sub.18 carboxylate, and the 
like, wherein R.sub.1 is an alkyl group containing about 12 to about 22 
carbon atoms and R.sub.2, R.sub.3 and R.sub.4 are alkyl groups containing 
1 to about 22 carbon atoms, arylalkyl groups containing 7 to 22 carbon 
atoms, aryl groups containing 6 to 22 carbon atoms and mixtures thereof. 
Preferred quaternary ammonium compounds are those wherein R.sub.1 and 
R.sub.2 are alkyl groups having about 12 to about 22 carbon atoms and 
R.sub.3 and R.sub.4 are methyl, those wherein R.sub.1 is an alkyl groups 
having about 12 to about 22 carbon atoms, R.sub.2 is benzyl, and R.sub.3 
and R.sub.4 are methyl, or mixtures thereof. 
The long chain alkyl groups can be derived from naturally occurring 
vegetable oils, animal oils and fats or petrochemicals. Examples include 
corn oil, cotton seed oil, coconut oil, soybean oil, castor oil, tallow 
oil and alpha olefins. A particularly useful long chain alkyl group is 
derived from hydrogenated tallow. 
Other alkyl groups which can be present in the quaternary ammonium compound 
are such groups as methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, 
decyl, dodecyl, lauryl, stearyl and the like. 
Aryl groups include phenyl and substituted phenyl. Arylalkyl groups include 
benzyl and substituted benzyl groups. 
Example of useful quaternary ammonium compounds are dimethyl 
di(hydrogenated tallow) ammonium chloride, methyl tri(hydrogenated tallow) 
ammonium chloride, dimethyl benzyl hydrogenated tallow ammonium chloride, 
methyl benzyl di(hydrogenated tallow) ammonium chloride and the like. 
Preferred quaternary ammonium compounds are dimethyl di(hydrogenated 
tallow) ammonium chloride, dimethyl benzyl hydrogenated tallow ammonium 
chloride and mixtures thereof wherein the mixtures can contain 99 to 1 
meqs of one compound to 1 to 99 meqs of the other compound. A particularly 
preferred mixture is one which contains equal meqs of each compound. 
The organosilane used in this invention has the structure 
EQU R.sub.n Si X.sub.(4-n) 
wherein n is an integer of 1 to 3, wherein R is an organic radical having a 
carbon atom directly linked to the silicon atom and wherein X is alkoxy, 
acryloxy, amino or halogen having no carbon-silicon linkage. R, the 
organic radical, contains from 1 to about 20 carbon atoms and can be 
alkyl, aryl, alkaryl, arylalkyl, vinyl, allyl, aminoalkyl, aminoaryl, and 
organic radicals which contain ether, ester and carboxyl groups. These 
organosilanes contain at least one group which is not hydrolyzable, the R 
group, and at least one group which can be hydrolyzed, the X group. 
The organosilanes useful in this invention are those which are primarily 
used as coupling agents in reinforced plastic manufacture. Such 
organosilanes are described in "Silane Coupling Agents" by E. P. 
Plueddemann, Plenum Press, New York (1982) and "Silicon Compounds-Register 
and Review", Petrarch Systems (1987), both of which are incorporated by 
reference. 
Examples of useful organosilanes include, but are not limited to, 
methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, 
dimethyldimethoxysilane, diethyldimethoxysilane, trimethylmethoxysilane, 
triethylmethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, 
triphenylethoxysilane, benzyltriethoxysilane, benzyldimethylethoxysilane, 
2-acetoxyethyldimethylchlorosilane, 3-acryloxypropyldimethylmethoxysilane, 
allyltrimethoxysilane, 4-aminobutyltriethoxysilane and the like. A 
particularly preferred organosilane for use in this invention is 
phenyltriethoxysilane. 
The compositions of this invention contain about 50 to about 150 meqs of 
the quaternary ammonium compound based on 100 grams of clay on a 100 
percent active basis, and, preferably, about 80 to about 130 meqs. The 
amount of silane reacted in the compositions of this invention is about 
0.5 to about 5 weight percent based on the theoretical weight of the 
reaction product of the clay and the quaternary ammonium compound and, 
preferably, about 1 to about 2.5 weight percent. 
The organophilic clays of this invention can be further modified by the 
incorporation of hydrogenated castor oil. It has been found that the 
thixotropic properties of the organophilic clays can be improved by the 
addition of up to about 25 weight percent hydrogenated castor oil wherein 
the weight percent is based on the total weight of organophilic clay and 
hydrogenated castor oil. 
In preparing the organophilic clays of this invention, the smectite type 
clays are slurried in water at a concentration of about 1 to about 10 
weight percent. The clay slurry is then filtered and/or centrifuged to 
remove impurities, such as sand particles. The cleaned slurry has a 
concentration in water of about 1.5 to about 5 weight percent and is 
heated to about 40.degree. to about 95.degree. C., preferably about 
60.degree. to about 75.degree. C. The quaternary ammonium compound and the 
organosilane compound, (preferably as an emulsion in water or alcohol,) 
are added. Agitation and heating are continued for about 15 minutes to 
about 2 hours to complete the reaction of the compounds with the clay. 
When the reaction is completed, the excess water is removed and the 
organophilic clay is dried. 
The compositions of this invention can be used as rheological additive in a 
wide variety of non-aqueous liquid systems. These clays are useful in 
paints, varnishes, enamels, waxes, adhesives, inks, laminating resins, gel 
coats and the like. The clays can be incorporated into the non-aqueous 
liquids using colloid mills, roller mills, ball mills and high speed 
dispersers. 
The compositions of this invention are particularly useful for preparing 
thixotropic crosslinkable compositions from unsaturated polyesters and 
unsaturated aromatic monomers. Unsaturated polyester compositions prepared 
from unsaturated acids or anhydrides and aliphatic diols in admixture with 
unsaturated monomers, e.g., styrene, are converted to crosslinked 
thermoset compositions by peroxide cure catalysis. Such compositions are 
particularly useful in the preparation of glass fiber laminates. 
Thixotropic agents, such as the organophilic clays of this invention, are 
added to such polyester composition in order to have workable low 
viscosities at high shear, such as is developed in mixing and spraying, 
and high viscosities at low or no shear to prevent flow and drainage of 
the polyester composition when applied to vertical surfaces. 
The compositions of this invention can be used in both the "pregel" and the 
"direct add" processes. The "pregel" process involves dispersing the 
organophilic clay in the styrene portion of the thermosetting polyester 
composition to form a gel. Just prior to use, this gel is then mixed in 
with the polyester. In the "direct add" process, the organophilic clay is 
added and dispersed in the solution of polyester and styrene. The 
organophilic clays of this invention are used with the unsaturated 
polyester-aromatic monomer compositions in the amount of about 0.5 to 
about 2 weight percent based on the weight of the polyester composition. 
The following examples describe the invention in more detail. Parts and 
percentages are by weight unless otherwise designated.

EXAMPLE 1 
To a suitable container are added two thousand parts of an aqueous slurry 
of Wyoming bentonite at 1.8 percent solids which had previously been 
centrifuged to remove non-clay impurities. Agitation is begun and heat is 
applied raising the temperature to 75.degree. C. To the slurry is added an 
aqueous emulsion of dimethyl di(hydrogenated tallow) ammonium chloride 
(DMD) in the amount of 90 milliequivalents (meqs) of the quaternary 
ammonium salt based on 100 grams of the clay. After mixing for 15 minutes 
at 75.degree. C., 1 weight percent of phenyltriethoxy-silane is added, 
said weight percent being based on the theoretical weight of the reaction 
product of the quaternary ammonium chloride an the clay. After additional 
heating and mixing at 75.degree. C., the organophilic clay product is 
recovered by filtration and is dried at 90.degree. C. for 24 hours. The 
dried product is ground and screened through a 170 mesh (U.S. Standard 
Sieve) screen. 
Additional organophilic clays are made using different milliequivalent 
amounts of dimethyl di(hydrogenated tallow) ammonium chloride and 
different amounts of phenyltriethoxy silane. Other clays are made using 
dimethyl benzyl hydrogenated tallow ammonium chloride (DBT) in place of 
the DMD quat. 
When the organophilic clays are modified with hydrogenated castor oil, the 
castor oil is blended with the dry organophilic clay. The hydrogenated 
castor oil (HC) is added in the amount of 25 weight percent based on the 
weight of the reaction product of the clay, quaternary ammonium salt and 
the silane. 
Table 1 lists the components used to make organophilic clays of this 
invention. Quat refers to the quaternary ammonium chloride. DBT is 
dimethyl benzyl hydrogenated tallow ammonium chloride. DMD is dimethyl 
di(hydrogenated tallow) ammonium chloride. The quat level, i.e., the 
amount used, is expressed in milliequivalents (meqs). The silane used is 
phenyltriethoxy silane. The amount used is weight percent based on the 
theoretical weight of the reaction product of the clay and quat. The 
organophilic clays also contain 25 weight percent hydrogenated castor oil 
based on total weight of the organophilic clay product and hydrogenated 
castor oil. 
TABLE 1 
______________________________________ 
Example Quat Quat level 
Silane Level 
______________________________________ 
1A DBT 90 0.5 
1B DBT 90 1.0 
1C DBT 90 1.5 
1D DBT 90 2.0 
1E DBT 80 1.0 
1F DBT 90 1.0 
1G DBT 100 1.0 
1H DBT 110 1.0 
1I DMD 80 1.0 
1J DMD 90 1.0 
1K DMD 100 1.0 
1L DMD 110 1.0 
______________________________________ 
EXAMPLE 2 
The organoclays are tested as thixotropic agents for unsaturated polyester 
compositions by the following procedure: 
A pregel is prepared by mixing until completely gelled 23 parts of styrene 
and 2 parts of organoclay. This pregel is then combined with 177 parts of 
unsaturated polyester and styrene containing 67 weight percent polyester. 
The mixture is stirred at 2000 RPM for 15 minutes. The viscosity using a 
Brookfield viscometer is determined at different RPM's at one hour, 24 
hours and 1 week. The viscosity data are listed in Table 2. Percentages 
where listed indicate the amount of settling i.e., the ratio of settled 
clay to liquid height. 
TABLE 2 
______________________________________ 
Example 
Time RPM. A B C D E F 
______________________________________ 
1 hr 2.5 832 904 836 764 212 752 
1 hr 5 524 574 560 508 194 504 
1 hr 20 242 259 282 253 145 256 
1 hr 50 171 182 187 188 134 192 
24 hrs 
2.5 88% 1160 90% 90% 272 1024 
24 hrs 
5 700 215 648 
24 hrs 
20 260 146 314 
24 hrs 
50 210 125 213 
1 wk 2.5 1232 1072 82% 82% 84% 1168 
1 wk 5 744 712 760 
1 wk 20 336 330 374 
1 wk 50 221 223 278 
______________________________________ 
Example 
Time RPM. G H J K L 
______________________________________ 
1 hr 2.5 744 748 512 528 496 
1 hr 5 518 510 392 368 352 
1 hr 20 263 272 190 200 190 
1 hr 50 178 186 145 141 138 
24 hr 2.5 944 960 720 896 720 
24 hr 5 696 656 696 656 720 
24 hr 20 326 312 316 312 336 
24 hr 50 218 210 214 213 226 
1 wk 2.5 1296 1168 1184 1232 1488 
1 wk 5 848 792 
1 wk 20 406 380 396 402 438 
1 wk 50 262 253 
______________________________________ 
EXAMPLE 3 
Thixotropic polyester compositions are made by the direct add method 
wherein 2 parts of organoclay as described in Example 1 is added to 200 
parts of an unsaturated polyester-styrene solution at 56% polyester 
solids. Viscosity determinations are made as described in Example 2. 
TABLE 3 
______________________________________ 
Example 
Time RPM A B C D E F 
______________________________________ 
1 hr 2.5 108 120 140 108 88 120 
1 hr 20 107 107 104 94 84 110 
24 hr 
2.5 300 360 260 336 24% 73% 
24 hr 
20 174 193 159 202 
1 wk 56% 91% 49% 78% 24% 54% 
______________________________________ 
Example 
Time RPM. G H J K L 
______________________________________ 
1 hr 2.5 240 132 192 112 64 
1 hr 20 134 120 110 90 76 
24 hr 2.5 320 65% 672 320 82% 
24 hr 20 166 234 180 
1 wk 24% 54% 94% 54% 99% 59% 
______________________________________ 
EXAMPLE 4 
Using the procedure described in Example 1, an organophilic clay is made by 
modifying 100 gms of bentonite with 90 meq. of DBT quat and 1.5 percent 
phenyltriethoxysilane. This clay is evaluated using the pregel procedure 
of Example 2. The viscosity results of the thixotropic polyester 
composition are as follows: 
______________________________________ 
Time RPM 1 hr 24 hr 
1 wk 
______________________________________ 
2.5 2200 3040 3160 
5 1760 2240 2360 
20 950 1205 1275 
50 708 906 974 
______________________________________ 
EXAMPLE 5 
To a suitable container are added two thousand parts of an aqueous slurry 
of Wyoming bentonite at 1.8 percent solids which had previously been 
centrifuged to remove non-clay impurities. Agitation is begun and heat is 
applied raising the temperature to 75.degree. C. To the slurry is added an 
aqueous emulsion of a mixture of dimethyl di(hydrogenated tallow) ammonium 
chloride (DMD) and dimethylbenzyl hydrogenated tallow ammonium chloride 
(DBT) in the amount of 47.5 miliequivalents (meqs) of DMD and 47.5 meqs of 
DBT based on 100 grams of the clay. After mixing for 15 minutes at 
75.degree. C., 1 weight percent of phenyltriethoxysilane is added, said 
weight percent being based on the theoretical weight of the reaction 
product of the aquaternary ammonium chlorides and the clay. After 
additional heating and mixing at 75.degree. C., the organophilic clay 
product is recovered by filtration and is dried at 90.degree. C. for 24 
hours. The dried product is ground and screened through a 170 mesh (U.S. 
Standard Sieve) screen. Hydrogenated castor oil (HC) is blended with the 
organophilic clay in the amount of 25 weight percent based on the weight 
of the blend. 
An unsaturated polyester-styrene composition is modified with the 
organophilic clay-hydrogenated castor oil blend in the amount of 1% by 
weight based on the total weight of the composition. Five grams of the 
polyester composition are poured on a 3".times.5" glass matt and is worked 
into the matt with a spiral laminating roller until air is removed. The 
matting is then placed at a 75.degree. angle and is observed for 48 hours. 
No drain-out is noted. Drain-out of 96% is observed after 24 hrs. with a 
polyester composition modified with fumed silica. 
The principles, preferred embodiments and modes of operation of the present 
invention have been described in the foregoing specification. The 
invention which is intended to be protected herein, however, is not to be 
construed as limited to the particular forms disclosed, since these are to 
be regarded as illustrating rather than restrictive. Variations and 
changes may be made by those skilled in the art without departing from the 
spirit of the invention.