Note: Descriptions are shown in the official language in which they were submitted.
~o7~0~6
Related Applications
None.
Backgrol1nd of the Invention
The field of the invention relates to phyllosilicate
minerals such as~ for example, the serpentines and micas, and
- certain fibrous amphiboles, such as, for example, amosite,
crocidolite, attapulgite and actinolite, which exhibit in their
structure, sequentially, octahedral layers containing oxides of
magnesium, aluminum and/or iron, and tetrahedral layers of
silicon and oxygen, which minerals have been modified for the
purpose of rendering them oleophilic or imparting to them certain
other desirable properties through having been coated by organo-
silanes. The invention further relates to a method for condition-
ing said minerals to enable same to react on their surfaces with
organo-silanes and to methods for effecting coatings on said
minerals with organo-silanes.
In the past, it has been recognized that certain phyllo-
silicate and fibrous amphibole minerals possess desirable char-
- acteristics for use in plastics and elastomer compounding. In
such applications, the most important active functions of these
materials are reinforcement, improvement of mechanical properties,
! heat resistance and flow control. In addition to the above uses,
certain of these minerals have found applications as additives in
oil-based fluid systems, such as, for example, lubricants, paints
and oil-well drilling fluids for modification of flow properties~
But in such applications, the unmodified minerals suffer the
innate limitation of being wet by water in preference to oil so
that composites incorporating them generally show impaired per-
formance ln the presence of moisture. Further, the unmodified
minerals do not ordinarily interact positively with oils,
plastics and elastomers forming at best only simple dispersions
therein upon physical mixing without any significant chemical
,' ~
1~'7~
bond being ~ormed between the minerals and the continuous phase.
Such dispersions are usually metastable with the mineral tending
to segregate from the continuous phase. It has now been dis-
covered that by superficially coating the preconditioned surface
of these minerals through chemical reaction with organo-silanes
the above-noted deficiencies can be overcome.
The technique of conditioning said minerals, to make
therein available free hydroxyl (silanol) groups for reaction
with organo-silanes, has been reported in the prior art. See
French Patent 2,098,467 issued February 14, 1972. In this prior
art, the layered minerals which are made up of alternating sheets
of magnesia and silica are subJected to the simultaneous ac~ion
of organo-silanes in concentrated mineral acid solution. The
effect of this solution on the layered mineral is to leach away
through the agency of strong acid the magnesia layers, leaving
the alternating silica inter-layers exposed for concomitant
chemical reaction with the organo-silanes, the process continuing
throughout the entire layered mineral system. The procedure re-
sults in the elimination of most, if not all, of the magnesia
layers leaving the alternating silica layers separated by layers
of chemically reacted organo-silane. The reaction is an in-depth
! reaction controlled by the rate of diffusion of the acid and
organo-silane into the body of the mineral as evidenced by the
required use of a large excess of concentrated acid, long reaction
periods and elevated temperatures.
The overall result of these combined reactions is that
instead of a superficial acid leach, i.e., removal of the outer
octahedral magnesium layer followed by surface reaction of the
exposed surface silanol groups with the organo-silane, the re-
action described in the prior art proceeds in depth removing mostof the total magnesia (or isomorphically substituted metal) leav-
ing an amorphous silica residue. This silica pseudomorph, which
1071076
lacks cyrstalline structure, is friable and has, of i~self, lit~le
or no mechanical strength. According to the prior art, this
material is a distinct organo-mineral polymer in contrast with
the superficially coated crystalline minerals of the present
invention.
Summary of the Invention
This invention relates to organo-silane coated phyllo-
silicate and amphibole minerals and to methods for producing sa~e.
The products obtained from the practice of this invention may be
categorized as falling within two broad end-use classes: Those
which possess thermally and chemically stable oleophilic sur-
faces; and those which possess surfaces which are capable of`
forming additional chemical bonds with reactive sites within
certain plastics and elastomers.
Those phyllosilicate and amphibole minerals which have
been rendered oleophilic according to the teachings of this
invention, have been found extremely desirable additives for con-
trolling the rheology of oil-based fluids used in oil and gas
well drilling, as gelling agents in grease and paint formulating,
as reinforcing agents for rubber and elastomer compounding~ and
as fillers for polyolefin resins and the like.
. I Those phyllosilicate and amphibole minerals whose sur-
faces have been rendered, according to the teachings of this in-
vention, capable of forming chemical bonds with reactive sites
within plastics and elastomers are particularly useful for the
improvement of mechanical properties, dimensional and thermal
stability, and moisture resistance of finished composites based
on phenolic, epoxy, acrylate and vinyl resins, as well as of both
sulfur- and peroxide-cured elastomer systems.
~inerals which have been rendered oleophilic, especially
chrysotile, have been found to be particularly effective in high
temperature environments. Without an oleophilic character,
.
,
~071~76
chrysotile, because of its affinity for water, has found only
restricted use in oil-thickening applications. As such systems
are exposed to elevated temperatures, in the presence of moisture,
chrysotile tends to become water-wet and to agglomerate or s~ttle
out of the system. By changing the surface characteristic of
chrysotile to oleophilic, this material can be effectively used
in oil systems to temperatures in excess of 350F. This invention
also relates to a method of preparing such surface altered
min~rals through a preliminary superficial acid leach of the
mineral and subsequent condensation with an organo-silane.
In accordance with the present invention, the mineral
is subjected to a superficial acid leach with dilute acid in
order to solubilize and remove the outer octahedral layer o
mixed magnesium~ aluminum, or iron oxides which is characteris-
tically present on the surface of such minerals. This reactionexposes silanol groups on the outer silicate layer so that they
are free to form silicon-to-oxygen-to-silicon-to-carbon bonds
through condensation with an organo-silane during a subsequent
reaction step. The superficial acid leach is carried out with
dilute acid, preferably a mineral acid such as hydrochloric or
sulphuric acid~ under conditions which maintain the basic
structural integrity of the mineral body. In the case of
chrysotile, this acid leach is accomplished with dilute acid
and under ambient temperature conditions accompanied by mild
agitation for periods up to about three hours.
The conditioned mineral is subsequently coated with
the desired organo-silane by mixing these constituents together
in the presence of a water miscible coupling agent such as
isopropyl alcohol. This coating reaction is carried out after
arresting the leaching action of the acid as by adding alkali to
the slurry obtained by the aforementioned acid leach or by
filtering out and washing the acid leached mineral.
,~
1071076
Detailed Description o~ the Invention
Minerals: Phyllosilicate and fibrous amphibole miner-
als which are suitable for modification in accordance with this
lnvention, are selected from a class of sequentially layered
minerals characterized by the presence of octahedral layers con-
taining magnesium, alu~ninum and/or iron oxides and tetrahedral
layers of silica. The preferred mineral is a phyllosilicate
denoted as chrysotile, a common form of asbestos. While
chrysotile is the preferred st.arting material, fibrous amphibole
such as crocidolite, amosite and attapulgite as well as other
phyllosilicate minerals such as biotite can be used in this
invention.
Silane Modifying Agent: In accordance with this in-
vention, phyllosilicates or fibrous amphiboles are modified
through reactlon with organo-silanes. These organo-silanes are
characterized by one of the two following structures:
,~ .
Structure
G - Si - Y
R'
- where G is a hydroxyl group or a group hydroxyzable to hydroxyl
such as, for example, alkoxy or halogen, Y is an alkyl group con-
taining from 1 to 20 carbon atoms, a phenyl group, or an alkyl
substituted phenyl group where the alkyl groups can contain a
total of from 1 to 12 carbon atoms; R and R' are selected fr~m
the groups described by G and Y or hydrogen; or:
Structure II
R
G- Si - Z
R'
. .
107107f~
where G is a hydroxyl group or a group hydroxyzable to a hydroxyl
such as, for example, alkoxyl or halogen: Z is an alkyl group
containing from..l to 20 carbon atoms bearing a functional group
such as, for example, amino, oxirane, mercapto or acryloxy, cap-
able of forming chemical bonds with reactive sites within poly-
mers and prepolymers or an allyl or vinyl groupj R and R' are
selected from the groups described by G and Z, hydrogen, an alkyl
group containing from 1 to 20 carbon atoms, phenyl, or alkyl sub-
stituted phenyl where the alkyl groups can contain a to~al of from
1 to 12 carbon atoms.
In accordance with one preferred embodiment of this in-
vention, it is desired to modify chrysotile by imparting oleo-
phillic properties to said mineral. It has been observed that
this is accomplished most effectively by the use of organo-
silanes selected from the class exemplified in Structure I, where-
in Y is an alkyl chain of from 2 to 18 carbon atoms. More
1 specifically, methyloctyl diethoxy silane has been found to be a
. preferred material for imparting such oleophilicity to the sur-
: face of chrysotile fibers. Methyldodecyldiethoxy silane,
decyltriethoxy silane, octyltriethoxy silane and heptyltrimethoxy
~ . silane are also desirable agents for imparting oleophilic
:~ ~ characteristics.
: ~ Further, in accordance with another embodiment of this
invention, it ls desired to modify chrysotile by imparting to
~ 25 said mineral and reactive sites within the structure of certain
types of polymers, copolymers, prepolymers, elastomers and
resins; for resins of the phenolic epoxy and urethane types,
. this is effectively accomplished by coating the mineral accordlng to the teachings of this invention with.organo-silanes of the
class exemplifled by Structure II, wherein Z is the 3-aminopropyl
group; for polymers, copolymers and elastomers based on isoprene,
.'
~071076
butadiene, butadiene-acrylonitrile or ethylene~propylene-diene,
for example, this is effectively accomplished by use of organo-
silanes of Structure II wherein Z is the 3-mercaptoethyl group;
and for polyolefins such as, for example, those based on
ethylene, propylene, isobutylene and the like or polymers based
on vinyl derivatives such as, for example, vinyl acetate,
methyl methacrylate, vinyl chloride, vinyl ethers and the
like, again according to the teachings of this invention,
this may be effected by use of organo-silanes selected from
Structure II in which Z is the vinyl or allyl group.
Acid Leaching of Minerals Preparatory to Coating:
According to the technique of this invention, the outer
octahedral layer of magne~ium, aluminum and/or iron oxides
must be eliminated by acid leaching to have available free
hydroxyl groups for reaction with alkoxy groups on the silanes.
As a leaching agent, it has been found that a mineral acid such
as hydrochloric or sulfuric are among the most suitable,
although other acids which form soluble salts of metallic
oxides in the outer octahedral layer such as nitric and acetic
acids can also be used.
Further, extreme conditions of reaction time and
temperature are to be avoided in order to control the leaching
so that only the surface layer of magnesium, iron and/or
aluminum compounds are removed. Thus, typically 0.3 to 0.5
; 25 parts of H2S04 acid by weight in about 10 parts of water
reacted with one part of chrysotile at a temperature of
60-800F for a period of up to three hours normally produces
a suitable superficial leaching to enable a satisfactory
bond to be formed between the organo-silane and the
mineral surface without appreciably degrading the
. .
1071076
basic structural integrity o~ the mineral as evidenced by X-ray
diffraction pattern comparison of chrysotile before and after
such a typical leaching treatment.
The leaching operation may be carried out in conven-
tional mixing equipment under moderate agitation. After the sur-
face leaching has been affected it is preferred that sodium or
potassium hydroxide be added to raise the pH of the reaction
mixture to a value in the range of 2-6.5. This is done to retard
undesirable further leaching and adjust the pH of the mixture to
within a suitable range for subsequent surface reaction with the
selected organo-silane.
Reacting the Conditioned Mineral with Silane: Accord-
ing to the preferred method of this invention, organo-silane,
preferably dissolved in a suitable water miscible solvent, is
added with agitation to the pH adjusted aqueous slurry of the
surface acid-leached mineral.
The organo-silanes are utilized in quantities of about
0.5%to about 10% based on the weight of the surface conditioned
mineral to be treated. In the specific case where the mineral
is chrysotile, 3-10% silane may be used to advantage, the
optimum amount being about 5%. If excess organo-silane is
employed, a portion of the excess may polymerize if the silane
contains two or three of the type groups as G in Structure I and
II and dimerize if the silane contains one such group. This
polymer or dimer may deposit on the surface of the mineral and
have a deleterious effect on subsequent performance.
The organo-silanes may be added to the aqueous mineral
slurry without dilution. However, particularly in the case where
the organo-silane possesses limited water miscibility, it is
advantageously added in the form of a solution in a water
misclble coupllng agent. Methyl, ethyl and isopropyl alcohols
and acetone have been found to be suitable coupling agents which
' ,
.
~07:1~76
will disperse the silane in water giving a homogenous mixture
upon agitation~ in which the silane is available for reaction
with the conditioned mineral surface. Normally, about three to
six times by weight of coupling agent to organo-silane is
employed.
- - The organo-silane is added to ~he aqueous mineral
slurry which is typically agitated for a period of about 4-16
hours at about room temperature. It has been found desirable to
keep the temperature of this reaction reasonably low in order to
minimize self polymerization of the organo-silanes which tends to
take place in the presence of water particularly at higher con-
centrations and elevated temperatures.
After reaction has been completed, the mineral is
separated from the aqueous phase. Organo-silane which may have
been added in excess and self-polymerized may be removed if
desired by washing with a suitable solvent (such as water,
isopropyl alcohol or benzene). The treated mineral is then
dried at about 220-250F and pulverized.
According to an alternate method of this invention, the
pH adjusted aqueous slurry of the surface acid-leached mineral is
'' t separated from the aqueous phase, dried at about 220-250F and
pulver-~zed. The pulverized acid-leached mineral is dispersed in
a non-aqueous solvent such as methanol or isopropanol or in a
` hydrocarbon solvent such as, for example, heptane or benzene.
The organo-silane is added to the mineral slurry without dilution.
": The mixture is typically agitated at ternperatures up to reflux
for a period of about one to eight hours, after which the mineral
~; is separated from the fluid phase. Organo-silane which may have
been added in excess and self-polymerized may be removed if
desired by washing with a suitable solvent (such as hexane or
acetone). The treated mineral is then dried at about 220-250F
and pulverized.
~071076
Example 1. Chrysotile asbestos was treated to possess
o:Leophilic surface properties in accordance with the present in-
vention as rOllOws: To a dilute solution of sulfuric acid, com-
posed of 300 cc of water and 9 g of 98% sulfurlc acid, 25 g of
chrysotile, having an average f~ber aspect ratio (length/dlameter)
of between about 200 and 1000, was dispersed and agitated on a
Hamilton Beach mixer for about 3 hours at ambient temperature
(70-75F). To this mixture 10 cc of 50% aqueous NaOH was added
to adjust the pH of the mixture to about 6.5. A solution of
2.5 g of methyloctyldiethoxy silane dissolved in 10 cc of
methanol was added to the stirred mixture and stirring continued
16 hours at ambient temperature to complete the reaction. The
surface reacted chrysotile was separated by filtration, washed
with water, and air dried at about 230F for 2 hours. Finally,
the dried product was ground for about 20-30 seconds at about
18000 rpm in a Waring blender.
Example 2. Chrysotile asbestos was treated to possess
oleophillic surface properties in accordance with the present
invention as follows: To a dilute solution of s~lfuric acid,
composed of 3000 cc water and 90 g of 98% sulfuric acid, 300 g of
chrysotile, having an average fiber aspect ratio (length/diameter)
of between 200 and 1000, was dispersed and agitated on a Hamilton
Beach mixer for about 3 hours at ambient temperature (70-75F).
To this mixture, 20 cc of 50% aqueous NaOH was added to ad~ust
the pH of the mixture to about 6.5. A solution of 30 g of
octyltriethoxysilane dissolved in 90 g of isopropanol was added
to the stirred mixture with stirring continued 16 hours at ambie-
temperatures (70-75F)to complete ~ereaction. The surface
reacted chrysotile was separated by filtration, washed with water
and air dried at about 230F for 16 hours and was ground for
about 20-30 seconds at about 18000 rpm in a Waring blender.
107107~;
Example 3. Chrysotile asbestos was treated to possess
o:Leophilic surface properties in accordance with the present in-
vention as follows: To a dilute solution of hydrochloric acid,
composed of 1600 cc of water and 400 cc of 37% hydrochloric acid,
2t)0 g of chrysotile, having an average fiber aspect ratio
(length/diameter) of between 200 and 1000, was dispersed and
agitated on a Hamilton Beach mixer for about one-half hour at
ambient temperature (70-75F). The surface washed chrysotile was
separated by filtration, washed with water and air dried at about
220F for about 16 hours and crushed in a mortar. To 100 cc of
heptane, 20 g of the surface washed crushed chrysotile and 2 g of
methyldodecyldiethoxysilane were added. The mixture was dispersed
and agitated on a magnetic stirrer for six hours at reflux. The
surface reacted chrysotile was separated by filtration, washed
wlth heptane and air dried at ambient temperature (70-75F) 16
hours and at about 230F for 2 hours.
Example 4. The oleophilic surfaces produced in
accordance with the procedures of Examples 1, 2 and 3 were by
this reaction verified by dispersing 10 g of the respective
reaction products in 350 cc of a mixture of 95 parts diesel oil
to 5 parts water by volume. In each case, the product formed
a stable dispersion in this medium whereas untreated chrysotile
asbestos fibers sub~ected to the same test prodecure became
water wet, flocculated and precipitated from the fluid.
Example 5. The oleophi~c surface properties imparted
to chrysotile, according to the teachings of this invention, were
evaluated as a gelling agent in an oil mud and compared to another
type of conventional gelling agent used in such systems. The
base mud used for thls evaluation was a 17.3 #/gal oil mud taken
from the Superior Oil Company, D.C. McMann #1, Gonzales County,
Texas. To prepare this field mud for a laboratory study, the mud
was passed through a 60 mesh screen and then heat aged at 375F
11
' ' : ' .: . - ,- - .
10~1076
rotating for 16 hours. This process thinned the system drastic-
ally making it susceptible for treatment with a gelling additive.
The mud was then split into 1 bbl/eq and treated with the
additives by shearing at 60 volts for 10 minutes on a Hamilton
Beach mixer. Rheological properties were measured at 150F and
then the samples were heat a~ed at 375F for 16 hours rotating.
After cooling to room temperature, the samples were sheared for
10 minutes and 60 volts and the rheology remeasured at 150F.
The following is a summary of this testing:
TABLE
Concentration Aging AV PV YP Gel
Additive #/bbl (in cps)(in cps)(in #/ Strength
100 (in #~100
ft2) f~ )
tinltial~
10 min.)
Blank 0 Immed. 41 37 7 3/4
16 hrs
at 375 41 38 6 4/6
Asbestos 6 Immed. 72 65 14 5/lo
16 hrs
at 375 lo 85 29 8/16
Asbestos Coated 6 Immed. 148 110 75 2g/36
per Example 1 16 hrs
Methyloctyldiethoxysilaneat 375 121 97 47 17/32
Asbestos Coated 6 Immed. 139 106 65 27/37
per Example 2 16 hrs
Octyltriethoxysilane at 375 145 114 59 18/29
Organophilic Clay 6 Irnmed. 70 60 20 9/8
of the Bentone 16 hrs
Class at 375 47 44 6 ~/7
These data indicate that the silane coated asbestos
materials are very effective in gelling oil muds.
Example 6. Chrysotile asbestos was treated to enable
35 the mineral surface to form additional chemical bonds with re-
active sites within resins of the phenolic, epoxy and urethane
types in accordance with the present invention as follows: To
a dilute solution of hydrochloric acid, composed of 2400 cc of
water and 600 cc of 37% hydrochloric acid, 300 g of chrysotile,
40 having an average fiber aspect ratio (length/diameter) of
1071076
between 200 and 1000, was dispersed and agitated on a Hamilton
Beach mixer for about one hour at ambient temperature (70-75F).
The surface washed chrysotile was separated by filtration,
washed with water and air dried at about 230F for about 16 hours
and ground for about 20-30 seconds in a Waring blender at about
18000 rpm. To 100 cc of heptane, 40 g of the surface washed
ground chrysotile and 4 g of 3-aminopropyltriethoxysilane were
added. The mixture was dispersed and agitated on a magnetic
stirrer for four hours at reflux. The surface reacted chrysotile
was separated by filtration, washed with heptane and air dried
for one-half hour at about 230F.
The fixed nitrogen content of the washed and dried
product was determined by the K~eldahl method to be o.38% by
weight. A similar analysis performed on the unreacted chrysotile
asbestos showed a 0.0% nitrogen content.
Example 7. Chrysotile asbestos was treated to enable
the mlneral surface to form additional chemical bonds with re-
active sites wlthin resins of the phenolic and epoxy types, in
accordance with the present invention as follows: To a dilute
solution of hydrochloric acid composed of 500 cc of water and
50 cc of 37% hydrochloric acid, 50 g of chrysotile having an
average ~iber aspect ratio (length/diameter) of between about
200 and 1000 was dispersed and then agitated on a Hamilton Beach
mixer for about 3 hours at ambient temperature (70-75F). To
this mixture 5 cc of 50% aqueous sodlum hydroxide was added to
ad~ust the pH of the mixture to about 6.5. ~ solution of 5 g
Ofb~eta-3-4-(epoxycyclohexyl)ethyltrimethoxysilane dissolved in
15 cc of isopropyl alcohol was added to the stirred mixture and
stirrlng continued 16 hours at ambient temperature to complete
the reaction. The surface reacted chrysotile was separated by
filtration, washed with water and air dried at about 230F for
16 hours. Finally the dried product was ground for about 30
seconds at about 18000 rpm in a Waring blender.
13
.. . ........... .
.
1071076
The fixed carbon content of the washcd and drled product
was determined by the combustion method to be 4.16% by welght.
A simllar analysls performed on the unreacted chrysotile asbestos
showed a 0.21% carbon content.
Example 8. Chrysotile asbestos was treated to enable
the mineral surface to form additional chemical bonds with re-
active sites within resins of the vinyl acetate, methyl
methacrylate, vinyl chloride, vinyl ethers and the like, in
. accordance with the present invention as follows: To a dilute
solution of sulfuric acid, composed of 1000 cc of water and
30 cc of 98% sulfuric acid, 100 g of chrysotile having an average
fiber aspect ratio (length/diameter) of between about 200 and
1000 was dispersed and then agitated on a Hamilton Beach mixer
for about three hours at ambient temperature (70-75F). The pH
f this mixture was ad~usted to 6.5 and then a solution of 10 g
Or methylvinyldlchlorosilane dissolved in 50 cc of isopropyl al-
cohol was added; the pH of that mixture readjusted to 6.5 and stir-
ring continued about 16 hours at ambient temperature to complete the
reaction. The surface reacted chrysotile was separated by
filtration, washed with water, methanol and air dried at about
230F for 16 hours. Finally, the dried product was ground for
about 30 seconds at about 18000 rpm in a Waring blender.
The fixed carbon content of the washed and dried
product was determined by the combustion method to be 1.1% by
weight. A similar analysis performed on the unreacted chrysotile
`asbestos showed 0.21% carbon content.
~ .
Example 9. Attapulgite, designated as Attagel 50~
obtained from Engelhard Minerals and Chemical Company, was treated
to possess oleophllic surface propertles in accordance with the
present lnventlon as follows: To a dilute solution of sulfuric
acid composed Or 400 cc Or water and 12 g o~ 98% sul~urlc acld,
40 g Or Attage ~ 50 was added and agltated on a Hamilton Beach
''~;.~ 11~ . '
~' ' ' '
: . , .. . ............ . - . . -
.- .
1071076
mixer for about three hours at ambient temperature (70-75F).
To this mixture 4 cc of 50% aqueous sodiu~ hydroxide was added
to ad~ust the pH of the mixture to about 6.5. A solution of
4 g of octyltriethoxy silane dissolved in 12 g of isopropyl
alcohol was added to the stirred mixture and stirring continued
16 hours at ambient temperature to complete the reaction. The
surface reacted attapulgite was separated by filtration and
washed with water and air dried at about 220F for 16 hours.
Finally the dried product was ground about 20-30 seconds at
about 18000 rpm in a Waring blender.
The reaction was confirmed by measuring the fixed
carbon content of the washed and dried product by the combustion
method and found to be 4.5% by weight. A similar analysis per-
formed on the unreacted attapulgite showed 1.1% carbon content.
The materials were stirred into a mixture of 332 cc of diesel
oil and 18 cc of water and rheology measured in a Fann
viscosimeter.
TABLE II
Concentration Viscosity Viscosity Gel Strength
at 600 at 300 Initial/10 mins.
#/bbl RPM RPM (#/100 ft2)
Unreacted
Atta-
pulgite 30 20 cps 12 cps 1/2
Reacted
Atta-
pulgite 30 27 cps 17 cps 3/6
Example 10. The oleophillic surface properties
imparted to chrysotile asbestos, according to the teachings of
this invention, were demonstrated by formulating and evaluating
two grease samples employing identical amounts of gelling agents, -
one of which was the unmodified chrysotile asbestos used to pre-
pare the oleophi~c derivatlve described in Example 2, and the
other being the reaction product of the surface acid leached
. . .- ~ :
'
:1071076
chrysotile asbestos and octyltriethoxysilane described ln
Example 2. Elghty-one g of the product obtained in Example 2
were milled for 5 minutes in a Waring blender at about 18Q00 rpm,
then added to 369 g of 300 S.u.s. mineral oil, worked to
uniformity with a spatula and finally passed through a Morehouse
Mill with 0.002 inch clearance. The second grease was then pre-
pared utillzing unmodified chrysotile asbestos in an identical
manner. The two grease samples were then characterized as
~ollows:
TABLE III
UnworkedWorked Water
Penetra- Penetra Drop Resis-
tion* tion* Point tance**
Grease formulated
with surface re-
acted chrysotile 273 275 500+F Passed
Grease formulated
wlth unreacted
chrysotile 301 316 480F Failed
*ASTM 217
**MIL-6-3278
Example 11. The oleophilic surface properties imparted
to chrysotile asbestos and further the water resistant nature of
polymer matrices employing such treated mineral fibers, as taught
in this invention, have been demonstrated by formulating and
evaluating three nitrile elastomers employing identical amounts
of reinforcing agents, one of which was the unmodified chrysotile
asbestos used to prepare the oleophilic derivative described in
Example 2, another being the reaction product of the surface acid
leached chrysotile asbestos and octyltriethoxysilane described
in Example ?, and the th~rd being carbon black, designated as
type N-326 whlch is commonly used as a nitrile rubber reinforcing
agent. Fifty parts of the product obtained in Example ~ were
milled, vulcanized and cured under standard conditions with 100
parts of nitrile rubber, and 12 parts of pasticizers, accelerators,
and curing agents normally employed in such formulations. The
16
- . ,
. - . ~ .
.
1071076
second and third samples were prepared in a like manner utilizing
unmodified chrysotile asbestos in one case and type N-326 carbon
black in the other, in lieu of the silane coated asbestos product
of E:xample 2.
These three samples were then tested for moisture
resistance according to the following procedure. Tensile strips
cut from cured slabs were weighed and suspended in an autoclave -
steam environment at 400F and 300 psig for 72 hours. The strips
were then taken from the autoclave and surface moisture removed. -
The slabs were then weighed immediately to determine moisture
uptake with the following results:
TABLE IV
Moisture Gain % Based
on Weight of Strip
Rubber compounded with surface
reacted chrysotlle of Example 2 -1.75
Rubber compounded with
unreacted chrysotile ~9.2
Rubber compounded with N-326
carbon black +5.6
Example 12. In order to illustrate the application of
materials of this invention as reinforcing agents for various
resin polymers and the ability of such materials to reduce water
absorption of such filled polymers, samples were prepared as
follows: 3.3 g of Shell R-15 epoxy resin were mixed with 0.5 g
of reinforcing agent andO.67 g of dipropylene triamine curing
agent added. This composition was cured for 16 hours at
100F. Water absorption tests were run according to ASTM
D 570-63. The results are set forth in Table Y'below:
TAB~E V
Rein~orclng Agent % Weight gain
Unreacted asbestos 1.82
Composition of Example 2 1.15
Composition of Example 6 1.57
Composition o~ Example 7 1.22
17
.: `
1071076
Similar results were obtained with a polymer compound
of 8.o g of polyester resin, 2.0 g of reinforcing agent and 0.4 g
of methylethyl ketone peroxide which was cured overnight.
Results are shown in Table VI below.
TABLE VI
Relnforcing Agent % Weight gain
Unreacted asbestos 0.575
Composition of Example 8 0.369
18
