Reinforcing fillers for plastics systems

A silane treated calcined clay, used as a filler in plastics such as polyamide or nylon resins, has improved tensile strength and flexural strength without substantial loss of impact strength, said calcined clay having been treated with a blend of silanes comprising an aminosilane and an alkylsilane.

FIELD OF THE INVENTION 
This invention relates to improved reinforcing fillers for plastics and 
more particularly relates to an improved reinforcing filler comprising a 
mineral substrate such as calcined clay which has been treated with a 
select blend of silanes. 
BACKGROUND ART 
It is known in the art that incorporating additives to plastics systems 
improve characteristics such as tensile strength, flexural strength, 
elongation or stretching, impact strength, and the like. Many 
thermoplastics, polyamides (nylons) in particular, are known to be 
moisture sensitive and will hydrolyze. Therefore, commercially anhydrous 
fillers are added to such resin systems. 
The preparation and subsequent utilization of minerals such as treated clay 
products as functional fillers for many different resin applications are 
well known to those skilled in the art. The final end-use applications for 
such filler products can range from rubber and plastics compounds (both 
thermoplastic and thermoset types) to uses in industrial coatings, caulks, 
sealants and adhesives. Several examples of treated calcined clays being 
used in filler type applications can be found in the patent literature. 
U.S. Pat. No. 5,244,958 (1993), describes the preparation of treated 
calcined clay products particularly useful as fillers in EPDM rubber 
insulation compounds. Useful calcined clay surface treatments included 
substituted silanes (e.g., those containing mercapto, amino, vinyl or 
alkyl type functionality), silazanes, polysiloxanes or select 
organometallic coupling agents (like organozirconates, organotitanates, 
etc.). 
U.S. Pat. No. 4,740,538 (1988), describes a treated calcined clay useful 
for nylon plastics whose surface treatment is a dual component system 
composed of an amino functional silane coupling agent and a 
triethanolamine or phenol impact modifier. The treated products of this 
invention are prepared by applying successive chemical surface treatments, 
i.e. a coating of impact modifier is subsequently coated with a deposit of 
aminosilane coupling agent. 
U.S. Pat. Nos. 4,467,057 (1984) and 4,280,949 (1981), describe the use of a 
silane-treated calcined clay in conjunction with a polymeric modifier 
additive to provide increased physical properties to articles molded from 
polyester compositions. 
U.S. Pat. No. 4,427,452 (1984), describes the use of a silane treated, 
flash-calcined kaolin clay as a functional filler in various elastomeric 
compositions. Substituted silane coupling agents containing either amino 
or mercapto type functionality are employed. 
U.S. Pat. No. 4,399,246 (1983), describes polyamide compositions containing 
a mineral filler (such as calcined clay or talc) together with low 
addition levels of an aminosilane and an N-substituted hydrocarbyl 
sulfonamide (both chemical additives being added "in situ") to provide 
molded plastic parts with improved impact resistance. 
U.S. Pat. No. 4,357,271 (1982), describes a polycarbonate molding 
composition containing a calcined clay filler which was pre-treated with 
aminosilane coupling agent. U.S. Pat. No. 4,235,835 (1980), describes a 
thermoset ethylene-vinyl acetate composition containing a 
vinylsilane-treated calcined clay as a functional filler. U.S. Pat. No. 
5,260,348 (1993), describes an improved, curable silicone-based 
composition containing a mineral filler, a cross-linking agent (e.g., an 
alkyl triacetoxysilane), some adhesion promoter (e.g., an epoxy or an 
amino functional silane) plus other various components. U.S. Pat. No. 
4,179,537 (1979), describes a dual component treatment system for 
inorganic fillers that improves the adhesion of glass to unsaturated 
thermoset resins. The preferred surface treatment used on glass consists 
of a blend of methacryl functional silane and an alkylsilane. U.S. Pat. 
No. 3,702,783 (1972), describes the treatment of glass filler with a 
prescribed mixture of epoxysilane and methylsilane to improve its bonding 
to organic resins like polyamides. 
While the treated calcined clay products described above are certainly 
related scientific art to the treated products of the present invention, 
none of them teach the use of a silane treatment mixture for minerals such 
as calcined clays comprising a unique blend of amino functional silane and 
an alkylsilane which together substantially improve the drop weight impact 
properties of resin systems and especially of highly filled polyamide 
compositions. For example, U.S. Pat. Nos. 4,399,246 and 4,740,538 both 
describe specific chemical additives used in combination with an 
aminosilane coupling agent to improve the impact properties of filled 
polyamide compositions. However, neither technology uses a second type of 
organosilane for this purpose. Furthermore, the first approach involves 
indirect treatment via the "in situ" addition of both chemical reagents 
during compounding of the nylon or polyamide composition while the latter 
approach requires successive clay treatment steps rather than the 
simultaneous silane treatment approach used in this invention. 
It is also known that while the addition of silane treated calcined clays 
in the appropriate amounts will improve tensile strength and flexural 
strength of polyamides, they will also decrease the impact strength of the 
polyamides. Therefore, a continuing problem in the art is to provide the 
required improvements in other characteristics of the polyamides without 
adversely affecting the impact strength of the polyamide. 
SUMMARY OF THE INVENTION 
It is according to one object of this invention to provide an improved 
filler for plastics systems such as polyamides. A further object of the 
invention is to provide an improved plastics product having improved 
flexural and tensile strength without corresponding loss of impact 
strength. 
A still further object of the invention is to provide an improved filler 
for resin systems comprising a mineral base such as calcined clay which 
has been treated with a dual silane blend and a method for the production 
of the treated mineral. 
Other objects and advantages of the invention will become obvious as the 
description proceeds. 
In satisfaction of the foregoing objects and advantages, there is provided 
by this invention an improved filler for plastics systems which comprises 
a mineral base such as calcined clay which has been treated on its surface 
by a blend of silanes, said blend of silanes comprising a mixture of an 
aminosilane and an alkylsilane. 
The present invention also provides a method for preparation of the silane 
treated mineral which comprises the simultaneous treatment of the calcined 
clay under fluidized turbulent conditions. 
Also provided by this invention are plastic products containing treated 
mineral fillers, said minerals having been pretreated with a dual 
component silane. 
BRIEF DESCRIPTION OF THE DRAWINGS 
Reference is now made to the drawing accompanying the application, wherein 
the figure is a graph illustrating Gardner DWI values compared with a 
silane treated clay in a filled Nylon 6,6. 
DESCRIPTION OF THE INVENTION 
In general, the present invention relates to novel, silane treated minerals 
such as calcined kaolin clay products which behave as highly functional 
fillers for resin systems and especially for polyamide resin systems (such 
as Nylon 6,6), in that the novel filler yields excellent Gardner drop 
weight impact values with little or no sacrifice in the resulting tensile 
and flexural properties. The silane treated mineral products of the 
present invention are produced by a silane-based surface treatment process 
utilizing a select combination of substituted organosilanes that are 
preferably applied simultaneously and substantially uniformly to the 
mineral as a mixture. The two silane components of choice in these 
treatment mixtures are amino functional silanes and alkylsilanes which 
must be combined in certain blend ratios to provide the desired drop 
weight impact improvements. 
In the preparation of the treated products of this invention, it is highly 
preferred that calcined kaolin clays be used as the starting inorganic 
filler material, due to their anhydrous nature, rather than using other 
clay minerals such as standard water washed or air-floated type hydrous 
clays. This preference is largely based on the fact that the treated 
fillers described herein are especially targeted for use in nylon 
compositions, as it is well known that polyamides (nylons) tend to be 
rather sensitive to moisture. Although calcined kaolin clays are the clay 
mineral substrate of choice for silane treatment in this invention and are 
exemplified herein, other suitable inorganic fillers commonly used in 
thermoplastics (such as talc, wollastonite or glass) can also be treated 
and successfully used as highly reinforcing fillers. 
Suitable calcined clay feedstocks, as defined herein, are those kaolin 
clays which have been substantially dehydroxylated and hence rendered 
X-ray amorphous as the result of being subjected to a very high 
temperature treatment process. Either "shock" or "conventional" clay 
calcining conditions, which are familiar to those skilled in the art, can 
be used to produce useful calcined clay feedstocks that should contain at 
least 50% by weight of its particles smaller than 2.0 microns in 
equivalent spherical diameter, but more preferably should contain at least 
65% by weight of its particles smaller than 2.0 microns. Ideally, the 
calcined clay feedstocks used for silane treatment and targeted for 
subsequent employment in various polyamide resins, should have an average 
Stokes Equivalent Particle Diameter of 0.5-1.6 microns. Two such calcined 
clay products meeting these fine particle size requirements are 
manufactured by the J. M. Huber Corporation under the product tradenames 
Huber 70C and Huber 90C. The typical physical properties of Huber 70C and 
Huber 90C are compared in Table I hereinafter. Given that these two 
calcined clays are used herein in demonstrating many of the preferred 
embodiments of this invention, they will for purposes of reading 
simplicity be hereafter referred to as just 70C and 90C, respectively. 
In preparing the treated calcined clay products of this invention, a very 
select combination of substituted organosilanes must be used together to 
produce the proper clay surface treatment needed to yield the desired 
Gardner drop weight impact improvements. In general terms, the two silane 
components of choice for these treatment mixtures are commonly known as 
amino functional silanes and alkylsilanes. A large number of different 
amino functional silanes and alkylsilanes are commercially available that 
can be successfully used as components of the calcined clay treatment 
mixture. The aminosilanes and alkylsilanes considered useful in producing 
the treated products of this invention can be defined from a compositional 
standpoint by the following chemical formulas: 
EQU Aminosilanes=RHN--(CH.sub.2).sub.a --SiR'.sub.b (OR").sub.3-b 
wherein: 
R=H or H.sub.2 NCH.sub.2 CH.sub.2 -- 
R"=C.sub.1 -C.sub.3 alkyl group 
R"=C.sub.1 -C.sub.3 alkyl, aryl or acetyl group 
a=a value of 1-6 
b=a value of 0 or 1 
and 
EQU Alkylsilanes=R* --SiR'.sub.b (OR").sub.3-b 
wherein: 
R'=C.sub.1 -C.sub.3 alkyl group 
R"=C.sub.1 -C.sub.3 alkyl, aryl or acetyl group 
R*=C.sub.1 -C.sub.20 alkyl group 
b=a value of 0 or 1 
Among the various aminosilane coupling agents defined above, the highly 
preferred choices include N-2-aminoethyl-3-aminopropyltrialkoxysilane, 
N-(2-aminoethyl)-3-aminopropylmethyldialkoxysilane, and 
3-aminopropyltrialkoxysilane, where in all cases, the hydrolyzable alkoxy 
substituents are most commonly either methoxy and/or ethoxy chemical 
groups. Among the various alkylsilane reagents, those which are preferably 
used for blending with an aminosilane include those having very long chain 
alkyl substituents containing from 8 to about 18 carbon atoms (i.e., R* 
=C.sub.8 -C.sub.18). Two examples of highly preferred alkylsilane reagents 
include n-Octyltrialkoxysilane and n-Octadecyltrialkoxysilane, where in 
both cases, the hydrolyzable alkoxy substituents are most commonly either 
methoxy and/or ethoxy chemical groups. It should also be pointed out that 
the preferred aminosilane and alkylsilane blending components, used in 
preparing the treatment mixtures of this invention, can contain either 
similar or dissimilar alkoxy substituents relative to one another and 
still provide the desired impact improvements for calcined clays. In the 
case where different alkoxy substituents are provided by the two silanes 
to be blended, it is well known to those skilled in the art that such 
silane mixtures will result in trans-esterification reactions. However, 
such side reactions between the individual silane molecules have not been 
observed to have any deleterious effects on silane product stability or on 
their eventual usefulness in producing treated fillers with good 
functional performance. 
One of the highly preferred embodiments of this invention is that the 
aminosilane and alkylsilane components do not have to be added separately 
in treating the calcined clay but can be pre-blended in the appropriate 
proportions to yield a treatment mixture. In addition, this 
aminosilane/alkylsilane treatment blend does not have to be used 
immediately but possesses excellent shelf-life (in the absence of moisture 
introduction). Good shelf-life properties for this silane blend are 
advantageous from a production logistics point of view, particularly when 
carrying out a continuous treatment process conducted over extended 
periods of time. 
In terms of maximizing the drop weight impact performance of treated 
calcined clay products targeted for use in nylon applications, the amino 
functional silane and alkylsilane reagents defined above need to be 
combined into treatment mixtures within a very specific range of silane 
weight ratios. The treatment mixtures of greatest utility have 
aminosilane/alkylsilane ratios ranging from about 1:1 up to 5:1 by weight, 
preferably about 3:1 to 5:1. In many instances, optimum filler 
reinforcement properties are obtained in polyamides (nylon) when using 
about a 3:1 weight ratio blend of aminosilane/alkylsilane for surface 
treatment. This 3:1 ratio silane blend thereby represents the most 
preferred treatment practice for our calcined clays. It is interesting to 
note that the impact performance benefits seen in nylon, through the 
blending in of small amounts of an alkylsilane with a conventional 
aminosilane treatment, are very unexpected in view of the individual 
performance characteristics of alkylsilanes and of aminosilanes, 
respectively. For example, it was discovered that octylsilane treated 70C 
or stearylsilane treated 70C products provide drop weight impact 
properties that are surprisingly no better than those obtained from an 
untreated 70C. Therefore one must conclude that select combinations of 
these two organosilanes, as dual surface treatments on calcined clay, 
provide truly synergistic reinforcement properties. 
In addition to the effects derived from the aminosilane/alkylsilane blend 
ratio, it was also noted that the total silane treatment level on the 
calcined clays does have a profound influence on final reinforcement 
properties. At the preferred aminosilane/alkylsilane weight ratios of 1:1 
to 5:1, the silane treatment levels generally useful in producing treated 
products in accordance with this invention range from 0.5% to 2.0% 
(percent total silane as based on weight of dry clay). However, silane 
treatment levels of about 1.1% to 1.6% are highly preferred particularly 
when utilizing a treatment blend having a 3:1 weight ratio of 
aminosilane/alkylsilane. 
It should be noted that the optimum silane treatment level for a given 
calcined clay filler is highly dependent upon its particle size and BET 
surface area properties. For calcined clays similar to Huber 70C (i.e., 
those with an average Stokes Equivalent Particle Diameter of about 1.4 
microns), the optimum treatment level of the 3:1 silane blend is about 
1.25%. In contrast, finer particle size calcined clays like Huber 90C 
(having an average Stokes Equivalent Particle Diameter of about 0.7 
microns) require a somewhat higher treatment level of 3:1 silane blend 
(about 1.50%) in order to yield their optimum filler performance in nylon 
compositions. 
As previously discussed, the treated calcined clay products of this 
invention function as highly reinforcing fillers in various polyamide 
resin systems. Polyamide resins for which these treated fillers are 
particularly well suited include all the common nylon thermoplastic 
grades, such as Nylon 6, Nylon 6,12 and Nylon 6,6. In these nylon 
applications, the treated fillers will yield excellent drop weight impact 
properties with little or no accompanying sacrifices in the tensile and 
flexural properties. In nylon, useful loadings of treated filler range 
from about 5% to 50% by weight, while those in the 20% to 40% range are 
particularly advantageous with respect to the combination of final 
compound properties provided. 
It should also be noted that the treated products described herein can 
behave as functional fillers in plastics systems other than nylon 
compositions due to the availability of some pendant amino functionality. 
Other end-use application examples for the fillers of the invention 
include unsaturated polyester thermoset resins and RIM 
polyurea/polyurethane compounds. In particular, the use of the treated 
calcined clays as fillers in polyester thermoset compositions designed for 
microwaveable dinnerware applications has found utility due to the high 
degree of food staining resistance imparted to the molded parts. In these 
dinnerware applications, it is believed that the hydrophobic 
characteristics imparted by the alkylsilane component of the 3:1 ratio 
treatment blend is largely responsible for improving the food staining 
resistance of such plastics under microwave use conditions. 
Another aspect of the present invention is a commercially viable, 
continuous silane treatment process for producing the treated calcined 
clay products described herein. The treated products of this invention can 
be readily made on a laboratory scale using batch treatment type processes 
that employ high speed, dry mixing equipment (such as a Littleford mixer 
or similar facsimile). These batch treatment processes work best when 
adding the silane treatment agents as a dilute alcohol solution (the 
silane concentration being typically 10-50% by weight) so as to aid 
surface treatment uniformity. However, treated 70C or 90C products made in 
this batchwise manner are not commercially practical processes for the 
kaolin industry as they often require a subsequent drying step to remove 
the residual alcohol. 
The treated calcined clay products of this invention are preferably made 
via a continuous silane treatment process utilizing an in-line, intimate 
solids/liquid mixing device (such as a Bepex Turbulizer unit or similar 
facsimile). 
A suitable apparatus for conducting the continuous process of the invention 
is described in U.S. Pat. No. 5,271,163, the disclosure of which is 
incorporated herein by reference. As shown in U.S. Pat. No. 5,271,163 a 
fluidizable cylindrical apparatus is provided within a housing with 
agitation provided within the housing by a plurality of paddles. The 
silane blend is sprayed into a highly fluidized chamber wherein the 
calcined clay solids are contained under agitation. The clay is added 
through a solids feeder and the silane mixture, which has been preblended, 
is added through a ratio controller by spraying with an injection pump. 
This treatment with the silane causes some liberation of alcohol which can 
be vented away under vacuum. In a preferred procedure, the alcohols are 
driven off by steam heating. The system may be provided with a steam 
jacket. The resulting product is a calcined clay in which the silanes are 
generally uniformly coated on the surface of the clay. 
In such continuous treatment processes, dilute alcohol solutions of silanes 
can still be utilized if absolutely necessary; however, it is greatly 
preferred to develop continuous processing conditions that allow the 
silanes to be added neat while maintaining good surface treatment 
uniformity. A continuous treatment process affording the ability to inject 
neat silanes thereby provides considerable advantages to a production 
facility in terms of reducing cost, simplifying logistics (through the 
elimination of an added drying step) and yielding improved manufacturing 
safety (by greatly reducing the potential flash hazards associated with 
high levels of alcohol). 
The aforementioned Bepex Turbulizer unit, when operated under the proper 
processing conditions, has been shown to produce treated 70C or 90C 
products using neat silane in a continuous manner with good surface 
treatment uniformity. This has been accomplished by operating the 
Turbulizer's mixing paddles at very high tip speeds (5000-6000 fpm) and by 
utilizing clay throughput rates of approximately 50-67% of the unit's 
rated capacity in order to well fluidize the dry calcined clay feed, while 
simultaneously metering in the liquid silane blend via spray nozzle 
injection. In addition, by operating the Turbulizer unit at temperatures 
of 60.degree.-100.degree. C. via use of its external steam jacket, it has 
been possible to eliminate the need for a subsequent drying step to remove 
the liberated alcohols from the treated calcined clay product. 
Finally, it should be pointed out that considerable technical effort has 
been previously expended in seeking to improve the impact properties of 
highly filled polyamide compositions. For example, U.S. Pat. Nos. 
4,399,246 and 4,740,538 each describe the use of a specific chemical 
additive in combination with an aminosilane coupling agent to improve 
impact properties. However, neither of these technologies uses a second 
type of organosilane reagent for this purpose. The teachings of the 
present invention are therefore substantially different from those of the 
prior art. 
U.S. Pat. No. 4,399,246 teaches a process wherein mineral treatment is 
accomplished indirectly via "in situ" addition of an aminosilane coupling 
agent and a sulfonamide additive to the nylon compound. It is generally 
well recognized in the technical literature, that pre-treated mineral 
fillers offer performance advantages over filled composites which have had 
the same coupling agents added at equivalent levels "in situ" during the 
resin compounding stage. Pre-treated mineral fillers, like those described 
herein, also offer the plastics compounder a significant convenience 
factor over utilizing "in situ" type processes by completely eliminating 
the difficult storage, handling and addition requirements of liquid silane 
reagents. 
U.S. Pat. No. 4,740,538 describes the use of a treated calcined clay 
product consisting of a dual treatment system that requires its surface 
treatment components to be applied in successive coating steps. In 
contrast, the treated products of this invention are readily produced in a 
one step, continuous treatment process involving the controlled addition 
of a pre-blended combination of silanes. 
It should be noted that the Turbulizer treatment process can also be 
successfully carried out through the simultaneous addition of two separate 
silane injection streams. However, given the excellent compatibility of 
the two organosilane components (one being an aminosilane and the other an 
alkylsilane) it is considerably easier from a production logistics 
viewpoint to have a single metering pump system for blended silane 
injection rather than two separate pump systems that must then both be 
ratio controlled relative to the existing calcined clay feed rate. 
The silane treated, calcined clay products of the present invention are 
highly useful as functional fillers for polyamide resin systems (such as 
Nylon 6,6) in that excellent Gardner drop weight impact values are 
provided with little or no sacrifices in the accompanying tensile and 
flexural properties. The fillers are applied to the nylon in a 
conventional manner. 
The present invention is further illustrated by the following treatment 
process and end-use application examples, which should be regarded as 
demonstrating only some of the preferred embodiments and not limiting 
thereof its scope or any equivalency. Unless otherwise indicated all 
calcined clay filler loadings and chemical treatment levels are based upon 
weight percentages. It should also be noted that all plastics physical 
testing programs herein presented on nylon compositions were conducted in 
accordance with recognized ASTM procedures. Table II lists the various 
physical properties that were typically measured in the nylon test 
programs along with the appropriate ASTM reference numbers. 
The preferred silane treated calcined clay filler product of this invention 
is white in color, has a specific gravity of 2.63, a surface of 7-9 BET 
m.sup.2 /g, an index of refraction of 1.54, a brightness, % reflectance of 
90-93, an average Stokes Equivalent Particle Diameter of 1.4 microns and a 
pH of 8-10.

EXAMPLE 1 
This silane treatment experiment demonstrates the unexpected functionality 
of various aminosilane/alkylsilane treatment mixtures on Huber 70C 
calcined clay for subsequent use in filled Nylon 6,6 applications. In 
particular, the performance benefits of long chain, aliphatic alkylsilanes 
(e.g., those having C.sub.8 -C.sub.18 alkyl groups), when used in 
combination with an amino functional silane in the proper weight 
proportions, are shown to significantly improve resulting drop weight 
impact values without large accompanying losses in tensile and flexural 
properties. 
The aliphatic alkylsilanes examined in this experiment include 
n-Octyltriethoxysilane and Stearylsilane (i.e., 
n-Octadecyltrimethoxysilane). These two alkylsilanes were thereby utilized 
in various blend combinations with 3-Aminopropyltriethoxysilane at a total 
silane addition level of 1.00% (silane percentage as based on weight of 
dry clay). Hence, aminosilane/alkylsilane blend ratios of 3:1, 1:1 and 1:3 
by weight were then applied to Huber 70C as respectively derived from 
using octylsilane (test compounds D, E and F of Table III) and from using 
stearylsilane (test compounds H, I and J of Table III). Comparative test 
controls were also included in this nylon program (test compounds B, C, G 
and K of Table III) consisting of an untreated 70C, aminosilane treated 
70C, octylsilane treated 70C and stearylsilane treated 70C, respectively. 
Test compound A of Table III shows the baseline physical properties of the 
unfilled Nylon 6,6 resin, which was Dupont's Zytel 101. 
The treated calcined clay products of Example 1 were all prepared batchwise 
on a laboratory scale using a Littleford W-10 mixer. In each case, 1200 
grams of dry Huber 70C was added to the Littleford mixer whose external 
jacket had been preheated to 70.degree. C. using hot water circulated from 
a Neslab RTE-210 temperature controller unit. The appropriate weight 
(12.00 grams) of each silane or silane blend, in neat form, was added 
slowly to the dry calcined clay being well mixed at medium speed. Upon 
complete silane addition, the contents were vigorously mixed at 1800 rpm 
for 20 minutes at 70.degree. C. The Littleford mixer was appropriately 
vented during the mix cycle to allow for the escape of all alcohol vapors 
eliminated from the reacted silanes. The treated 70C products were then 
removed and allowed to cool to room temperature. The silane treatment 
level of each product was verified analytically, using a Leco carbon 
combustion unit, prior to their compounding use in Nylon 6,6 resin. 
Test batches of Nylon 6,6 resin and 70C based filler (from above) were 
blended together at 40% filler loadings and subsequently compounded on a 
ZSK 30mm twin screw extruder. Test specimens were then molded and 
pertinent physical properties measured as summarized in Table III. 
TABLE I 
______________________________________ 
TYPICAL PHYSICAL PROPERTIES 
FOR CALCINED CLAYS 
PHYSICAL PROPERTY HUBER 70C HUBER 90C 
______________________________________ 
Pigment Specific Gravity 
2.63 2.63 
B.E.T. Surface Area, m.sup.2 /gm 
7-9 13-17 
Moisture, % Maximum As 
0.5 0.5 
Produced 
+325 Mesh Screen Residue, 
0.02 0.01 
% Max. 
Average Stokes Equivalent 
1.4 0.7 
Particle Diameter, microns 
Oil Absorption, gm/100 gm clay 
46-56 75-85 
(ASTM D-281) 
Brightness, % 90-93 92-94 
pH (@ 28% solids) 5.0-6.0 5.0-6.0 
Index of Refraction 
1.54 1.54 
______________________________________ 
TABLE II 
______________________________________ 
TESTING PROCEDURES USED IN 
NYLON PLASTIC PROGRAMS 
Test Property ASTM No. 
______________________________________ 
Tensile*Modulus, psi D-638 
Tensile*Strength, psi D-638 
Flexural**Modulus, psi D-790M-86 
Flexural**Strength, psi D-790M-86 
Elongation at Break, % D-638 
Notched Izod Impact, ft.-lbs. 
D-256 
Gardner Drop Wight Impact, in.-lbs. 
D-3029 
Heat Deflection Temp. (@ 264 psi), .degree.C. 
D-648-82 
______________________________________ 
NOTE: 
*Tensile CrossHead Speed = 0.2 in./min. 
**Flex CrossHead Speed = 0.1 in./min. 
TABLE III 
__________________________________________________________________________ 
COMISON OF OCTYLSILANE vs. STEARYLSILANE TREATMENT SYSTEMS 
ON HUBER 70C IN NYLON 6,6* APPLICATION 
Test Compounds 
Property A B C D E F G H I J K 
__________________________________________________________________________ 
Filler Loading, % 
0.0 40 40 40 40 40 40 40 40 40 40 
Calc. Clay Filler** 
none 
70C 
70C 70C 70C 70C 70C 70C 70C 70C 70C 
Clay Surface 
Treatments:*** 
% Aminosilane 
none 
none 
1.00% 
0.75% 
0.50% 
0.25% 
-- 0.75% 
0.50% 
0.25% 
-- 
% Octylsilane 
-- -- -- 0.25% 
0.50% 
0.75% 
1.00% 
-- -- -- -- 
% Stearylsilane 
-- -- -- -- -- -- -- 0.25% 
0.50% 
0.75% 
1.00% 
Tensile Modulus, 
349.5 
653.9 
713.5 
710.4 
730.1 
720.0 
668.7 
644.4 
646.9 
658.7 
698.0 
psi (.times.10.sup.3) 
Tensile Strength, 
11.3 
10.2 
13.4 13.7 13.5 13.6 10.9 13.4 13.2 12.6 11.1 
psi (.times.10.sup.3) 
Flexural Modulus, 
426.9 
839.0 
782.3 
845.7 
850.4 
810.8 
811.3 
816.1 
807.2 
790.4 
790.3 
psi (.times.10.sup.3) 
Flexural Strength, 
16.8 
16.9 
23.4 22.2 21.9 21.2 17.3 21.9 21.7 23.7 26.5 
psi (.times.10.sup.3) 
Elongation at 
34.5 
2.3 
4.8 5.4 4.7 4.7 2.7 6.4 5.0 3.8 3.4 
Break, % 
Notched Izod Impact, 
0.79 
0.40 
0.71 0.73 0.69 0.53 0.41 0.76 0.69 0.52 0.49 
ft.-lbs. 
Gardner Drop Weight 
&gt;160 
10 37 46 42 18 8 48 57 25 11 
Impact, in.-lbs. 
Heat Deflection 
70.1 
103.6 
104.5 
104.6 
104.6 
104.3 
102.0 
104.7 
106.9 
97.7 96.9 
Temp. (@ 264 psi), 
.degree.C. 
__________________________________________________________________________ 
NOTE: 
*Nylon 6,6 resin used was Dupont's Zytel 101. 
**70C = "Huber 70C" fine particle size, calcined kaolin clay (Average 
Stokes Equivalent Particle Diameter = 1.4 microns). 
***For treated clay versions, total silane addition level = 1.00% (as 
based on weight of dry clay). Aminosilane = 3Aminopropyltriethoxysilane; 
Octylsilane = nOctyltriethoxysilane; Stearylsilane = 
nOctadecyltrimethoxysilane. 
The test data of Table III reveal several interesting points as summarized 
below: 
1.) The treated 70C products prepared from aminosilane/alkylsilane blends 
(Tests D, E, F, H, I and J) all yielded significant performance 
improvements in elongation at break, Izod impact and Gardner drop weight 
impact relative to the untreated 70C control (Test B). These performance 
enhancements were all achieved with minimum sacrifices in tensile and 
flexural properties. 
2.) Relative to a conventional aminosilane treated 70C (Test C of Table 
III), improved Gardner drop weight impact values were provided by the 
treated products derived from the aminosilane/alkylsilane treatment blends 
of 3:1 or 1:1 weight ratio (Tests D, E, H and I). The 3:1 treated 70C 
products also showed performance advantages in elongation at break 
relative to straight aminosilane treatment. The above performance 
advantages are seen in Nylon 6,6 compounds independent of whether 
octylsilane or stearylsilane was employed as the alkylsilane component in 
the 70C treatment blends. However, it should be noted that somewhat 
superior drop weight impact results were provided with stearylsilane, but 
were gained at the expense of some tensile and flexural properties 
relative to that obtained with octylsilane. 
3.) When one compares the performance properties of the various treated 70C 
products, a synergistic benefit is seen in utilizing select treatment 
mixtures of aminosilane and alkylsilane not readily predicted on the basis 
of their individual silane performance attributes. For example, compare 
the superior performance of test compounds D and H (both containing a 3:1 
treated 70C) to those of compounds C, G and K. In particular it is 
interesting that the alkylsilane treatments when used alone on 70C 
actually yield drop weight impact values no better than that obtained with 
an untreated 70C. The excellent functionality of the 3:1 ratio 
aminosilane/alkylsilane treated 70C products described herein is therefore 
truly unexpected. 
EXAMPLE 2 
In Example 1, improved Gardner drop weight impact properties were shown to 
be provided by treated 70C products whose silane surface treatment 
consisted of an aminosilane/alkylsilane mixture having a blended weight 
ratio of at least 1:1 or higher. In this example, several 
aminosilane/octylsilane blend ratios greater than 1:1 are examined as 
surface treatments for 70C. In addition, total silane addition levels of 
1.00% as well as 1.25% (as based on weight of dry clay) are respectively 
utilized at each aminosilane/octylsilane blend ratio. This matrix of 
treatment experiments thereby allows us to determine the performance 
effects of silane blend ratio as a function of total treatment level on 
70C. 
In this treatment study, n-Octyltriethoxysilane was the alkylsilane reagent 
of choice to be blended with 3-Aminopropyltriethoxysilane. The aminosilane 
and octylsilane were blended together at active weight ratios of 4:1, 3:1 
and 2:1 respectively. These various silane blends were then applied neat 
to 70C at the appropriate treatment level using the Littleford W-10 mixer 
under exactly the same processing conditions as previously described in 
Example 1. The target treatment levels of 1.00% or 1.25% were verified by 
Leco carbon combustion analysis. The resulting 70C based test products are 
identified in Table IV as test compounds M, N, O, P, Q and R. An untreated 
70C was also included in the nylon test program to serve as a comparative 
control (compound L of Table IV). 
Test batches of Nylon 6,6 resin and treated 70C filler were thoroughly 
blended together at 36% filler loadings and subsequently compounded on the 
ZSK 30mm twin screw extruder. Dupont's Zytel 101 was used as the Nylon 6,6 
resin. Molded specimens were then prepared and fully tested. The resulting 
test data are summarized in Table IV, from which several interesting 
conclusions can be drawn as discussed below: 
1.) In terms of maximizing impact properties (both Izod and Gardner drop 
weight) as well as elongation at break, it is very clear that 70C should 
be surfaced treated with a 3:1 weight ratio blend of 
aminosilane/octylsilane. In comparison, the 2:1 and 4:1 treatment blends 
always yielded lower physical properties on 70C. Furthermore, increasing 
the silane treatment level of 3:1 ratio blend up to 1.25% had some further 
positive influence on Izod impact (e.g., compare the Izod impacts of test 
compounds N and Q). In terms of its overall performance properties, test 
product Q thereby represents the most preferred embodiment of this 
example. Test product Q employs a 3:1 ratio aminosilane/octylsilane 
treatment blend at a total treatment level of 1.25%. 
2.) Although the 3:1 ratio aminosilane/octylsilane treatment blend on 70C 
significantly improved nylon impact properties as well as elongation at 
break relative to using an untreated 70C, little to no accompanying losses 
in tensile and flexural properties were obtained. 
TABLE IV 
__________________________________________________________________________ 
COMISON OF VARIOUS AMINOSILANE/OCTYLSILANE TREATMENT BLENDS 
ON HUBER 70C IN NYLON 6,6* APPLICATION 
Test Compounds 
Property L M N O P Q R 
__________________________________________________________________________ 
70C Loading**, % 36 36 36 36 36 36 36 
Clay Surface Treatments:*** 
% Aminosilane none 
0.80% 
0.75% 
0.67% 
1.00% 
0.94% 
0.83% 
% Octylsilane -- 0.20% 
0.25% 
0.33% 
0.25% 
0.31% 
0.42% 
Tensile Modulus, psi (.times.10.sup.3) 
769.2 
743.5 
810.1 
724.2 
737.7 
762.6 
817.7 
Tensile Strength, psi (.times.10.sup.3) 
11.7 
12.5 13.0 12.9 12.7 13.3 13.1 
Flexural Modulus, psi (.times.10.sup.3) 
804.2 
741.4 
783.7 
795.0 
742.3 
785.0 
840.7 
Flexural Strength, psi (.times.10.sup.3) 
20.3 
20.3 21.0 21.4 20.7 21.4 22.2 
Elongation at Break, % 
2.6 
6.9 7.7 5.8 5.1 8.0 5.0 
Notched Izod Impact, ft.-lbs. 
0.53 
0.80 0.83 0.79 0.90 0.97 0.92 
Gardner Drop Weight Impact, in.-lbs. 
12 39 56 40 44 55 40 
__________________________________________________________________________ 
NOTE: 
*Nylon 6,6 resin used was Dupont's Zytel 101. 
**70C = "Huber 70C" fine particle size, calcined kaolin clay (Average 
Stokes Equivalent Particle Diameter = 1.4 microns). 
***For treated clay versions, total silane addition level = 1.00% (for 
test systems M, N & O) and 1.25% (for test systems P, Q & R). Silane 
addition levels are based on weight of dry clay. Aminosilane = 
3Aminopropyltriethoxysilane; Octylsilane = nOctyltriethoxysilane. 
EXAMPLE 3 
In Example 2, a 3:1 ratio aminosilane/octylsilane treatment blend was shown 
to be optimum on 70C calcined clay at a total treatment level of 1.25%. 
The test results in Nylon 6,6 were all based on treated 70C products 
prepared by applying a surface coating of neat silane blend using the 
Littleford W-10 mixer. In this example, additional silane treatment 
experiments are conducted on 70C to demonstrate the dramatic effect that 
different clay processing conditions have on final filler reinforcement 
properties. 
In this treatment process study, a 3:1 ratio aminosilane/octylsilane 
treatment blend was again the clay surface treatment of choice to be 
applied at a target treatment level of 1.25%. Test systems V, W and X of 
Table V thereby represent such treated 70C products, but each was prepared 
by completely different processing means. The processing method used for 
each is fully described below: 
PROCESS 1 
Test product V was produced by a laboratory scale, batch treatment process 
using a Hobart dough mixer for providing relatively low speed, room 
temperature mixing conditions. In the Hobart treatment method, 1000 grams 
of dry 70C clay was added to the stainless steel mixing bowl and low speed 
mixing was started. Some 3:1 ratio aminosilane/octylsilane blend was then 
diluted with methanol to a 10% total silane concentration for subsequent 
addition to the calcined clay. Based on a 1.25% active treatment level of 
blended silanes, 125.0 grams of 10% silane solution was added very slowly 
to the 70C with continuous product mixing. The purpose of adding the 3:1 
ratio silane blend as a dilute alcohol solution rather than neat was to 
increase the likelihood of providing a well distributed, uniform surface 
treatment on the calcined clay filler. Once all the 10% silane solution 
had been added, low speed product mixing at room temperature was continued 
for an additional 30 minutes. The treated 70C clay was then transferred to 
a metal pan and dried at 110.degree. C. for three hours in a forced air 
oven to complete silane reaction and remove residual alcohol. The targeted 
treatment level was verified by Leco carbon combustion analysis. 
PROCESS 2 
Test product W of Table V was produced on a laboratory scale using a 
slightly modified procedure of the previously described Littleford 
treatment method. In contrast to the Littleford treatment runs of Examples 
1 and 2, the 3:1 ratio aminosilane/octylsilane blend was diluted with 
methanol to a 25% total silane concentration for subsequent addition to 
the calcined clay. A silane solution was employed here to potentially 
increase surface treatment uniformity relative to that achieved with neat 
silane addition. Based on a 1.25% active treatment level of 3:1 ratio 
silanes, 60.0 grams of 25% silane solution were added slowly to 1200 grams 
of dry 70C which was being continuously mixed at medium speed and had been 
preheated to 50.degree. C. The contents were then vigorously mixed for an 
additional 20 minutes at 1800 rpm while maintaining the 50.degree. C. 
temperature. The treated 70C product was removed, allowed to cool to room 
temperature and then analyzed by Leco carbon to verify its targeted 
treatment level. 
PROCESS 3 
Test product X was produced on a commercial scale via a continuous 
treatment process employing an 8 inch Bepex Turbulizer unit. Using an 
Accurate volumetric feeder system, dry 70C was continuously fed into the 
Turbulizer unit at a constant rate of 800 lbs/hr. The 8 inch Turbulizer 
was equipped with an external steam jacket that was heated to 80.degree. 
C. with hot, pressurized water during the treatment run. The Turbulizer 
was also vented, under slight vacuum, to separate the liberated alcohol 
vapors from the treated 70C product. The Turbulizer's mixing paddles were 
operated at a high tip speed of 5330 fpm so as to completely fluidize the 
dry calcined clay feed. Under these highly fluidized conditions, liquid 
silane blend was continuously injected in at the appropriate rate using a 
metering pump to yield the target 70C treatment level of 1.25%. The 3:1 
ratio aminosilane/octylsilane blend was in this case used neat (rather 
than as a dilute methanol solution) due to the intense solids/liquid 
mixing action provided by the Turbulizer unit. At a 70C feed rate of 800 
lbs/hr, the 3:1 ratio silane blend was thereby injected at a rate of 85 
ml/min to achieve the target treatment level of 1.25%. Product treatment 
level was again verified by Leco carbon combustion analysis. It should 
also be pointed out that test product U (which has a 1.25% treatment level 
of straight aminosilane) was produced by the same Turbulizer treatment 
process under identical conditions and thereby serves as a comparative 
test control. 
The 70C based test products of Table V were thoroughly blended with Nylon 
6,6 resin (Dupont's Zytel 101) at 40% filler loadings and subsequently 
compounded on the ZSK 30mm twin screw extruder. Molded specimens were then 
prepared and fully tested. The resulting test data are summarized in Table 
V. 
TABLE V 
__________________________________________________________________________ 
COMISON OF TREATMENT PROCESSES FOR AMINOSILANE 
AND AMINOSILANE/OCTYLSILANE TREATMENT SYSTEMS 
IN NYLON 6,6* APPLICATION 
Test Compounds 
Property S T U V W X 
__________________________________________________________________________ 
70C Loading, % 0.0 40 40 40 40 40 
Clay Surface Treatments:** 
% Aminosilane none 
none 
1.25% 
0.94% 
0.94% 
0.94% 
% Octylsilane -- -- -- 0.31% 
0.31% 
0.31% 
Tensile Modulus, psi (.times.10.sup.3) 
424.9 
831.5 
834.8 
819.8 
858.6 
856.4 
Tensile Strength, psi (.times.10.sup.3) 
10.8 
12.2 
13.6 13.0 13.6 13.5 
Flexural Modulus, psi (.times.10.sup.3) 
383.2 
805.2 
847.5 
812.9 
831.6 
851.9 
Flexural Strength, psi (.times.10.sup.3) 
14.6 
19.5 
22.3 20.7 21.8 22.1 
Elongation at Break, % 
53.5 
2.3 
7.5 5.8 9.1 7.9 
Notched Izod Impact, ft.-lbs. 
0.60 
0.51 
0.70 0.72 0.70 0.68 
Gardner Drop Weight Impact, in.-lbs. 
&gt;160 
11 65 23 101 98 
__________________________________________________________________________ 
NOTE: 
*Nylon 6,6 resin used was Dupont's Zytel 101. 
**Silane addition levels are based on weight of dry clay. Aminosilane = 
3Aminopropyltriethoxysilane; Octylsilane = nOctyltriethoxysilane. Treated 
Huber 70C calcined clays were prepared as follows: 
a) U and XContinuous treatment process via 8 inch Bepex Turbulizer. 
b) VBatch treatment process via laboratory Hobart mixer. 
c) WBatch treatment process via laboratory W10 Littleford mixer. 
The principal conclusions drawn from these 70C treatment experiments are 
summarized below: 
1.) In comparing the performance of test-products V, W and X it is clear 
that the low speed mixing conditions associated with the Hobart mixer 
yield an inferior treated 70C product as compared to the continuous 
method. In particular, the Gardner drop weight impact provided by test 
product V was roughly 25% of that provided by W or X despite its use of 
large diluent quantities of methanol for aiding uniform silane treatment. 
The obvious conclusion is that intense solids/liquid mixing action yields 
greater silane surface treatment uniformity on 70C calcined clay which 
especially manifests itself in improved Gardner drop weight impact 
properties. 
2.) It is interesting to compare the physical properties of test compound W 
(Table V) with those of compound Q (from Table IV of Example 2). Both 
compounds utilize a treated 70C clay product having a 1.25% treatment 
level of 3:1 ratio aminosilane/octylsilane blend. The method of silane 
treatment via the Littleford mixer was somewhat different (W used a 25% 
silane treatment solution versus neat silane addition in producing Q). 
Although direct head to head comparisons between these two test programs 
cannot be made due to the difference in compound filler loadings (40% 
versus 36%) and in the two lots of Zytel 101 resin, it is still quite 
evident that a significant improvement in Gardner drop weight impact was 
provided by utilizing a silane treatment solution in the Littleford mixing 
process. Gardner drop weight impact increased from 55 inch-lbs (for Q) up 
to 101 inch-lbs (for W) despite the higher filler loading used in the 
latter test compound. 
3.) A comparison of test compounds W and X indicates virtually equivalent 
performance properties in Nylon 6,6. The ability to commercially produce a 
fully equivalent treated 70C product via a "continuous" treatment process 
using neat silane injection offers a tremendous production cost and 
logistics advantage over "batch" treatment processes using dilute silane 
solutions. 
4.) A comparison of test compounds X and U (wherein both treated fillers 
were prepared via the Turbulizer treatment process) clearly illustrates 
the performance advantages provided by the 3:1 ratio 
aminosilane/octylsilane treatment blend over straight aminosilane 
treatment on 70C calcined clay. At equal treatment levels of 1.25%, 
Gardner drop weight impact was improved approximately 50% as compared to 
use of conventional aminosilane treatment. 
EXAMPLE 4 
In this experiment, a series of silane treated 70C products were produced 
via neat silane addition using the Turbulizer treatment process previously 
described in Example 3. Treated 70C clay products were produced using 
aminosilane and 3:1 ratio aminosilane/octylsilane blend, respectively, 
over a range of treatment levels of from 0.75% to 1.75%. As in previous 
examples, the aminosilane and octylsilane reagents employed were 
3-Aminopropyltriethoxysilane and n-Octyltriethoxysilane. Product treatment 
levels were verified by Leco carbon combustion analysis. 
The various treated 70C products were then compounded into Nylon 6,6 resin 
(Dupont's Zytel 101) at a 40% filler loading using the ZSK 30 mm twin 
screw extruder. Molded specimens were prepared and tested. The Gardner 
drop weight impact properties are plotted in the Figure as a function of 
the silane treatment level on 70C. Performance advantages in Gardner drop 
weight impact for the 3:1 ratio aminosilane/octylsilane treatment blend 
are seen across the entire treatment level range, but the impact 
improvement on 70C is by far the greatest at a treatment level of about 
1.25%. 
EXAMPLE 5 
In this experiment, Huber 90C (a very fine particle size calcined clay) was 
surface treated with the 3:1 ratio aminosilane/octylsilane blend at a 
total silane treatment level of 1.50%. The 3:1 ratio silane blend was 
applied neat using the Turbulizer treatment process as previously 
described in Example 3. A higher silane treatment level was needed on 90C 
(versus the 1.25% on 70C) in order to maximize its drop weight impact 
properties in Nylon 6,6. However, the use of a higher silane treatment 
level is not totally unexpected given the greater BET surface area of 90C 
versus 70C (see Table I for a comparison of properties). Product treatment 
level was verified by Leco carbon combustion analysis. 
For testing purposes, the treated 90C product was compounded into Nylon 6,6 
resin (Dupont's Zytel 101) at a 40% filler loading. An untreated 90C was 
also included in this nylon test program to serve as a comparative 
control. The resulting test data are summarized in Table VI. As can be 
readily seen from the performance data of Table VI, the Izod impact, 
Gardner drop weight impact and elongation at break properties of 90C 
calcined clay can all be substantially improved through appropriate 
surface treatment with the 3:1 ratio aminosilane/octylsilane blend of this 
invention. These 90C performance enhancements can also be achieved with 
little to no loss in accompanying tensile and flexural properties. This 
example thereby demonstrates that the novel treatment technology described 
herein provides functionality to calcined clay fillers of extremely fine 
particle size (i.e., those having an average Stokes Equivalent Particle 
Diameter of less than 1.0 micron). In addition, it should be noted that 
the treated 90C product (Test Z of Table VI) offers a few performance 
advantages over that provided by the preferred treated 70C product of 
Example 3 (Test X of Table V). A comparison of test products X and Z 
indicates that the latter provides more than a 100% improvement in tensile 
modulus, while some modest improvements were also seen in Izod and Gardner 
drop weight impact properties. These performance improvements are for the 
most part believed attributable to the significantly finer particle size 
associated with test product Z. 
The invention has been described herein with reference to certain preferred 
embodiments. However, as obvious variations thereon will become apparent 
to those skilled in the art, the invention is not to be considered as 
limited thereto. 
TABLE VI 
______________________________________ 
COMISON OF TREATED AND UNTREATED 
VERSIONS OF HUBER 90C CALCINED CLAY 
IN NYLON 6,6* APPLICATION 
Test Compounds 
Property Y Z 
______________________________________ 
90C Loading**, % 40 40 
Clay Surface Treatments:*** 
% Aminosilane none 1.125% 
% Octylsilane -- 0.375% 
Tensile Modulus, psi (.times.10.sup.3) 
1,968.0 1,781.0 
Tensile Strength, psi (.times.10.sup.3) 
12.8 13.8 
Flexural Modulus, psi (.times.10.sup.3) 
853.2 837.8 
Flexural Strength, psi (.times.10.sup.3) 
20.4 22.1 
Elongation at Break, % 
1.1 4.9 
Notched Izod Impact, ft.-lbs. 
0.41 0.79 
Gardner Drop Weight Impact, in.-lbs. 
10 112 
______________________________________ 
NOTE: 
*Nylon 6,6 resin used was Dupont's Zytel 101. 
**90C = "Huber 90C" very fine particle size, calcined kaolin clay (Averag 
Stokes Equivalent Particle Diameter = 0.7 microns). 
***For treated clay version, total silane addition level = 1.50% (@ 3:1 
Aminosilane/Octylsilane wt. ratio). Silane addition level is based on 
weight of dry clay. Aminosilane = 3Aminopropyltriethoxysilane; Octylsilan 
= nOctyltriethoxysilane.