Heat-resistant composite material and method of making same

Composite article, and method of producing same, comprising a heat-resistant woven fabric substrate having a continuous heat and wear-resistant coating thereon for handling hot glass articles and the like without marring same. The heat-resistant flexible composite material is formed from a tightly woven fabric such as thermoset polyaramid fibers with a continuous imperforate coating of organic-inorganic silicone resin containing a filler of heat-resistant particulate material therein adapted to withstand extensive repeated contact with newly-formed hot glass articles. As required, the flexible composite material may be used alone or as a facing for a rigid structural member formed of metal.

CROSS-REFERENCE TO RELATED APPLICATIONS 
A related U.S. patent application is entitled, "Improvements in the 
Manufacture of Glass Wherein Hot Metal Molds are Provided With a Solid 
Film Lubricant Layer", Ser. No. 562,554, filed Mar. 27, 1975, now 
abandoned, and refiled as Ser. No. 727,322, filed September 27, 1976, the 
latter issued as U.S. Pat. No. 4,110,095 on Aug. 29, 1978, in the name of 
the same applicant and assigned to the same common assignee as the present 
application. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to flexible composite materials which are 
extremely heat-resistant, and methods of making same, which materials have 
a continuous layer or coating of solid film lubricant or glass release 
agent which essentially comprises an organic-inorganic silicone resin 
having a finely-ground particulate filler therein. The layer or coating is 
formed by taking an essentially solventless organopolysiloxane resin or 
mixture of such resins and dispersing a prescribed amount of finely-ground 
particulate material therein, the combined materials being applied to and 
heat cured on a woven fibrous substrate comprised of a polymeric thermoset 
material such as polyaramid fibers or similar high-temperature resistant 
substrates. The selected substrate after coating may be severed into 
precisely-sized and shaped contours prior to or subsequent to heat-curing 
the resin containing the filler material. 
The composite material may be fabricated into conveyor belting, sweep arm 
covering, tong liners, and the like, for handling newly-formed hot glass 
articles without marring their surfaces or creating objectionable 
emissions from the composite material due to excessive heat. The coating 
cures into a thermoset hardened condition on the substrate surface while 
permitting the substrate to retain an appreciable degree of flexibility. 
Normally, the polymeric fibrous substrate, while possessing an appreciable 
amount of heat resistance, cannot be employed alone without a suitable 
heat-resisting coating for long-term repeated handling of hot glass 
articles. 
2. Description of the Prior Art 
It has been common practice in the glass forming art to fabricate or cover 
conveyor belts for transporting hot glass articles with asbestos or 
asbestos-containing materials such as transite to provide heat-resistant 
surfaces which would not mar the glass and provide long-term operating 
life. Also, bucket liners and sweep arm fingers have previously been 
fabricated with coverings of asbestos cloth for handling hot glass 
articles. 
In the production of glassware, certain handling equipment has also been 
coated with graphite and petroleum oil swabbing compositions to provide 
lubricity and heat-resistance. In the use of such coatings, when the 
petroleum fraction flashes off, it can detract from effective lubrication 
during forming. 
The use of water-based carriers instead of the petroleum oil carriers for 
graphite and other lubricous materials have not been entirely satisfactory 
primarily due to the high heat of vaporization of water and the resulting 
excessive cooling of the glass-handling equipment. In addition, it is 
difficult to controllably wet the handling equipment surfaces with 
water-based materials which are applied intermittently during production 
of glassware. 
SUMMARY OF THE INVENTION 
The present invention comprises a composite product having a unique 
combination of materials including a cured hard organopolysiloxane resin 
containing a filler of non-colloidal lubricating particulate material 
which is applied over a tightly-woven thick fabric such as thermoset 
polyaramid fibers. The invention relates to generally flexible composite 
materials which are extremely heat-resistant, and methods of making same, 
which materials have at least one continuous layer or coating of solid 
film lubricant or glass release agent which essentially comprises an 
organopolysiloxane resin having a finely-ground particulate filler 
therein. The combined coating constituents are applied over a woven 
fibrous substrate comprised of a polymeric thermoset material such as 
polyaramid, and the like, and heat-cured thereon. The substrate may be 
severed into precisely-sized and shaped contours prior to heat-curing the 
resin or combined resins containing the filler material for use alone or 
as a convering over other rigid surfaces. The layer or coating composition 
is formed of a solid film lubricant or glass release agent which 
essentially comprises a finely-divided heat-resistant filler dispersed in 
a solventless thermoset cured, hard organopolysiloxane binder. The layer 
or coating is formed by introducing the dispersion of fine fillers into an 
organic solventless solution of a further-curable, thermosettable, 
solvent-soluble organopolysiloxane resin which is applied over the woven 
polymeric fibrous substrate and then curing said organopolysiloxane to a 
thermoset hard condition. 
Accordingly, an object of the present invention is to provide an improved 
hot glass handling base material. 
Another object of the present invention is to provide a composite material 
which provides long-term effectiveness in repeated contact with 
newly-formed hot glass articles. 
Another object of the present invention is to provide improved hot glass 
handling capability to existing conveyors, scoops, buckets, and the like, 
by providing a flexible heat-resistant fibrous composite material with a 
continuous solventless organopolysiloxane coating thereon adapted to cover 
the glass contacting surfaces of such equipment. 
Yet another object of the present invention is to provide a method of 
making a high heat-resistant composite material which is capable of 
repeated contact with hot glass articles over an extensive period without 
deterioration of the material or detrimental marking of the glass 
articles. 
Still another object of the present invention is to provide a heat and 
wear-resistant woven fabric substrate having a continuous coating of 
solventless silicone resin and finely-divided filler thereon in cured 
thermoset hardened condition adapted to long-term repeated handling of hot 
glass articles. 
These and other objects and features of the present invention will become 
apparant from the following detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The base material upon which the combined layer or coating composition is 
applied is preferably comprised of polyaramid fibrous yarn, such as 
commonly manufactured and sold under the trademark "Kevlar" by the E. I. 
duPont de Nemours & Company. Such polyaramid fibers or yarn are commonly 
fabricated into a variety of special industrial products exhibiting high 
modulus of rupture. Among the more significant characteristics of 
polyaramid yarn are high tensile strength, resistance to combustion and 
flame retardancy, resistance to stretch, and good surface abrasion 
resistance. The material is useful over a wide range of temperatures 
without deterioration or degradation and has a thermal conductivity 
generally similar to asbestos fibers. 
This material has a tensile strength of about 400.times.10.sup.3 psi, a 
density of about 1.4 gm/cm.sup.3, a modulus of elasticity of 8.5 MM psi, a 
percentage elongation of 4.07% at breakage, and a melting or decomposition 
point of about 930.degree. F. The material can be employed to weave thick 
fibrous cloth which may be used as conveyor belts and insulating cloth or 
pads. The material possesses very good thermal resistance, as well as 
excellent chemical resistance to most common chemicals. 
The polyaramid material can be woven into tight belting, as thick as about 
1/4 inch, with or without a metal wire core for long term use. Various 
thicknesses of the Kevlar polyaramid fabric can be employed as the 
substrate. Other materials can be employed as the substrate so long as 
they possess high temperature resistance to degradation and can be 
fabricated into interwoven fibrous form. Among such other materials which 
may be used as the flexible substrate are ceramic fiber cloth such as 
manufactured by the Carborundum Company, and carbon cloth manufactured by 
American Kynol, Inc., all of which are comprised of high-temperature 
resistant fibers or yarn adapted to be fabricated into cloth. 
The carbon cloth is essentially a phenolic fiber, known as carbonized 
Kynol, or Kynol novoloid precursor fiber, which is formed by formaldehyde 
curing of melt-spun novolac resin. Curing results in the formation of 
methylol groups, dimethyl ether bonds, and methylene bonds, and because of 
its three dimensionally crosslined structure, the fiber thus obtained is 
infusible. The fiber is capable of being carbonized directly, without the 
need for intermediate infusibility treatment. 
The ceramic fiber cloth may be comprised of Fiberfrax ceramic fiber which 
in textile form contains 15 to 25% organic fiber added during the carding 
process to produce roving. Such textiles have superior insulating ability 
to 2300.degree. F., and excellent resistance to thermal shock, corrosive 
attack, and breakdown due to mechanical vibration and stress. They are 
available from The Carborundum Company. The materials can be double woven 
to provide exceptional strength and be heat-treated to remove all 
organics. 
The ceramic fiber products are easily able to withstand temperatures as 
high as 1800.degree. F. Such material in fabric form is able to maintain 
high tensile strength while resisting thermal shock and abrasion. Such 
fibers are composed of alumina silica and offer much better dimensional 
stability than amorphous silica fibers. 
Polyaramid fabric, when woven into 3-ply cloth, has properties generally 
comparable to asbestos cloth as shown by the following table: 
______________________________________ 
Thick- Temperature 
Weight ness Heat Transfer 
Rise 
FABRIC (Oz./yd.sup.2) 
(Mills (Cal/cm.sup.2 sec) 
(.degree.F.) in 25 sec 
______________________________________ 
Polyaramid 
Fibers 29.5 86 .163 55 
Asbestos 
40.7 91 .169 56 
______________________________________ 
EXAMPLE NO. I 
A preferred example of the coating composition which may be employed to 
coat the aforesaid polyaramid fabric substrate material with a heat and 
ware-resistant layer to be contacted by the hot glass consists of the 
following constituents: 
______________________________________ 
COM- 
PO- 
AMOUNT NENT CONSTITUENT 
______________________________________ 
70 gms (A) Reactive Intermediate Silicone Resin 
GE Product No. SR-191 
30 gms (B) Polysiloxane Glass Resin 
O-I Product No. T-908 Regular 
5 gms (C) Butylated Melamine-Formaldehyde Resin 
Koppers Amino Resin 70-10 
20 gms (D) Finely-divided Graphite 
Union Carbide Product No. 38 
5 gms (E) Finely-divided Red Iron Oxide 
Pfizer Product No. R-5098 
______________________________________ 
The reactive silicone resin may be described as a methoxy functional, 
essentially solventless, 100% non-volatile, clear liquid reactive 
intermediate silicone resin, General Electric Product No. SR-191. It is 
used as a silicone-polyester copolymer vehicle for heat-cured finishes 
which are normally applied by coil coating methods to prefinished metal 
surfaces. It may also be used as a vehicle for paint and other surface 
coatings. Copolymers of the subject silicone resin and other organic 
resins can be prepared using conventional resin process techniques and 
equipment. Copolymer vehicles which are prepared using the subject 
silicone resin component (A) possess extremely high durability and 
resistance to loss of gloss, color fade and chalking. Typical properties 
of the SR-191 silicone resin are: 
______________________________________ 
Methyoxy Content (Wt %) 15 
Average Combining Weight 206 
Specific Gravity (@ 77.degree. F.) 
1.13 
Weight per gallon (lbs) 9.4 
Viscosity - Brookfield (@ 77.degree. F.) 
80 
Approximate Number Average 
Molecular Weight 600 
______________________________________ 
The Owens-Illinois Glass Resin Polymer, Product No. T-908 Regular, 
Component (B), is an organopolysiloxane resin designed for high 
temperature laminating applications which require considerable retained 
flexural strength when the laminate is exposed to elevated temperatures 
for a prolonged period of time. 
The subject organopolysiloxane resins are produced by the co-hydrolysis and 
co-condensation of different alkoxysilanes employing the steps of: (a) 
heating the reaction mixture to form a partial condensation product, (b) 
concentrating this product, (c) precuring the concentrated product, and 
(d) finally curing the precured product. The resins are useful as 
machinable, heat-resistant, thermoset bodies or as coatings. The subject 
resins and processes of making same are disclosed and claimed by U.S. Pat. 
No. 3,389,121 to Burzynski and Martin, issued June 18, 1968, assigned to 
the same common assignee as the present invention. 
The following properties are typical of flake prepared from Owens-Illinois 
Glass Resins No. T-908 Regular: 
______________________________________ 
Weight Loss to Gel 3-4% 
Weight Loss Gel to Cure 
3-4% 
VISCOSITY (BROOKFIELD) 
of 50% solution in xylene (w/w) 
21 cps 
of 40% solution in xylene (w/w) 
9 cps 
of 30% solution in xylene (w/w) 
5-6 cps 
______________________________________ 
The flake resin is fully soluble in the following solvents: Benzene, 
xylene, tetrahydrofuran, acetone, diethyl ether, ethanol, chloroform, and 
ethylenedichloride. 
The Product No. T-908 resin refers to a hardenable thermosettable 
organpolysiloxane resin solution (60% by weight resin solids in xylene) in 
which the organic groups are methyl and phenyl siloxane, and wherein the 
ratio of these organic groups, i.e., the ratio of methyl and phenyl 
radicals per silicon aton (R:Si ratio) is about 1:4 and wherein the ratio 
of methyl and phenyl radicals on a mol basis is about 3.3:1, both of these 
values being based on analyses. The T-908 solid resin is soluble in the 
liquid SR-191 resin. The T-908 resin in the prepolymer liquid form is also 
compatible with the SR-191 resin to produce the liquid coating base 
material. 
The cure promoter, Component (C), for the two above-described resins is 
normally present in an amount less than about 15% by weight based on 
organopolysiloxane solids. The cure promoters which are employed may be 
routinely selected by those skilled in the art and are materials which are 
conventionally employed for curing further-curable organopolysiloxanes. 
Especially suitable cure promoters which are known for curing 
organopolysiloxane are the melamine-formaldehyde partial condensate 
resins, which term refers to alkylated melamine formaldehyde partial 
condensate resins. The alkylated melamine formaldehyde resins are melamine 
formaldehyde types in which alkylation is effected with lower alkyl 
alcohols, or mixtures thereof, such as the C.sub.1 and C.sub.5 alkalyl 
alcohols. One such suitable composition, Component (C), is that 
manufactured by the Koppers Chemical Company as their Amino Resin 70-100 
butylated melamine formaldehyde partial condensate resin. When the 
melamine formaldehyde partial condensation resins are used to promote the 
curing of the organopolysiloxane, satisfactory results are obtained by 
using between 0.5% and 1.0% by weight up to about 14% or 15% by weight of 
the melamine formaldehyde partial condensate resin based on 
organopolysiloxane solids by weight. Other suitable cure promoters or 
catalysts include the phosphonic acids such as those disclosed in U.S. 
Pat. No. 3,654,058, and phenyl phosphonic acid is especially preferred in 
an amount of about 5% by weight based on the organopolysiloxane. It is not 
necessary to use a cure promoter in all formulations of the aforesaid 
resins since desirable results can be obtained both with and without such 
constituent in the coating composition. 
Dry particulate, non-colloidal graphite is intimately combined with the 
organopolysiloxane resins to form a dispersion of the graphite therein. 
The weight ratio of the graphite to the organopolysiloxane resin solids in 
forming the dispersion is preferably on the order of about 0.8:1 to about 
2:1. An especially desirable ratio is about 1:1 to about 2:1 with a weight 
percentage of about 16% being most beneficial. Where greater lubricity is 
desired in the final cured coating, a higher ratio of graphite to 
organopolysiloxane resins solids is used. In some cases of the aforesaid 
example where higher lubricity is desired, up to 25% graphite may be 
employed. A particularly useful graphite, Component (D), to be employed in 
the subject coating consists of Union Carbide Product No. 38, manufactured 
and sold by Union Carbide Chemical Company. In general, such graphite is 
described as electric furnace, or synthetic, graphite and is supplied as a 
dry finely-divided particulate material. 
The red iron oxide, Component (E), serves as a pigment, in addition to the 
graphite, for providing both heat-resistance and a glass-release mechanism 
to the silicone and organopolysiloxane resins. The red iron oxide is 
normally produced by thermal decomposition of ferrous sulfate under 
controlled oxidizing conditions, followed by water grinding and washing to 
eliminate soluble salts. This pigment wets easily, has excellent 
suspension properties, is chemically stable, and provides a low-cost, very 
pure refractory oxide material. The red iron oxide is manufactured by 
Pfizer Minerals Corp., Pigments and Metals Division, as Product No. 
R-5098. This material is essentially pure Fe.sub.2 O.sub.3 having a 
spheroidal particulate shape with a 0.2 percent weight loss on ignition. 
Also black iron oxide can be used as the pigment. This is Pfizer Product 
No. BK-5000 which also is essentially pure Fe.sub.2 O.sub.3 having a cubic 
particulate shape with no weight loss on ignition. 
The above-described coating composition is applied over the fibrous 
substrate in the form of a continuous imperforate layer by techniques such 
as brushing. Preferably two or more coatings are applied over the 
substrate to obtain a thickness of from about 8 to 12 mils as preferred. A 
coating layer of about 0.45 to 0.50 grams per square inch is especially 
desirable. The coating layer on the substrate is cured by heating in an 
air-circulating oven for about one hour at 500.degree. to 600.degree. F., 
with the higher limit being preferred. Following such curing, the coating 
is very adherent to the substrate and penetrates the pores and interstices 
of the fabric very deeply. In the case where organic processing aids are 
used on the fabric, or on the yarn or roving for making the fabric, longer 
cure times would be required to eliminate any such organic materials. The 
fabric exhibits a greater stiffness when coated and the coating is cured 
to a hardened thermoset condition, but still possesses the property of 
being generally flexible for use as conveyor belting, and the like. The 
term "generally flexible" as used herein refers to a coated fabric 
substrate which is sufficiently flexible for conveyor belting applicable 
to continuous operation around a pair of six-inch pulleys. 
EXAMPLE NO. II 
Another example of the coating composition which may be employed to coat 
the polyaramid fabric substrate material consists of the following: 
______________________________________ 
COM- 
AMOUNT PONENT CONSTITUENT 
______________________________________ 
70 gms (A) Reactive Intermediate Silicone Resin 
GE Product No. SR-191 
30 gms (B) Polysiloxane Glass Resin 
O-I Product No. T-908 
20 gms (D) Finely-divided Graphite 
Union Carbide Product No. 38 
______________________________________ 
The catalyst is not used in the aforesaid composition; however, adequate 
curing of the resins is obtained upon heating the coating to about 
600.degree. F. for approximately one hour. The resins may still be cured 
into tough, hardened thermoset condition exhibiting no tackiness. 
A thinner woven fabric of polyaramid fibers which is termed "ballistics 
grade" may also be used as the substrate. Such material is less than about 
0.20 inch thick and tightly woven from a continuous filament to resist 
extremely high impact, being manufactured and sold by Clark-Schwebel Fiber 
Glass Corp., White Plains, New York. Product No. Kevlar-29 supplied by 
such manufacturer which is termed a "ballistic fabric" is useful as the 
fibrous substrate. Such product having a plain weave and designated as 
Style No. 713 has the following properties: 
8.0 oz/sq. yd. 
0.014 inch thickness 
TENSILE STRENGTH (lbs/sq. inch) 
970 Warp 
970 Fill 
YARN DENIER 
1000 Warp 
1000 Fill 
The coating composition is applied over the fibrous substrate in the form 
of one or two thin impervious coating layers with the substrate having the 
desired basic shape or contour. The coated material may be attached by a 
high-temperature silicone rubber adhesive to a rigid base plate such as a 
20 gauge steel plate. The coating on the fabric substrate is then cured, 
such as by heating the fabric substrate and underlying base plate, at a 
temperature of about 500.degree. to 550.degree. F. for approximately one 
hour. The finally-cured composite material on the metallic base plate is 
adapted to handling hot glass articles over prolonged periods without 
adverse effects on said articles or the base plate. The base plate may be 
further shaped such as by bending or punching following applications of 
the fibrous composite material and curing same thereon. 
In installations where a non-conductor for low heat transfer is required, 
the above-described base plate is particularly desirable for long-term 
use. The subject base plate is softer than bare metals to provide a 
cushioning effect when readily deformable hot glass articles are deposited 
thereon by dropping same through a short vertical distance. The base plate 
exhibits substantial heat-resistance with minimal wear when contacted 
repeatedly by newly-formed hot glass articles or molten glass charges. It 
is possible to create a prescribed pattern of apertures in the base plate 
for air cooling of such articles without detrimental checks. Such 
apertures can be formed such as by punching through the composite fibrous 
substrate and base plate without adverse effects to fabricate an 
air-cooling dead plate, for example. 
EXAMPLE NO. III 
With regard to the preferred ranges of constituents to be used in the 
coating composition, where no catalyst or curing agent is employed, the 
following table sets forth such ranges in weight percent. 
______________________________________ 
PRE- COM- 
RANGE FERRED PONENT CONSTITUENT 
______________________________________ 
54 to 64% 
56% (A) Reactive Intermediate 
Silicone Resin 
GE Product No. SR-191 
16 to 30% 
24% (B) Polysiloxane 
Glass Resin 
O-I Prod. 
T-908 Regular 
14 to 23% 
16% (D) Finely-divided 
Graphite 
Union Carbide 
Product 
No. 38 
0 to 10% 
4% (E) Finely-divided 
Red 
(when used) Oxide - 
Pfizer Prod. 
No. R-5098 
______________________________________ 
In formulating the coating composition, the red iron oxide may or may not 
be used as desired. For some applications, it is useful to include both 
the graphite and red iron oxide in the coating as pigments, while in other 
applications, the graphite alone is preferred. The composition is 
formulated as described in Example No. I with the coating applied to the 
fibrous substrate and then cured into hardened condition. The fibrous 
substrate may or may not be backed with a rigid metal plate, depending 
upon the end use requirements. 
The composite material with the subject coating on its glass contacting 
surface, when permanently attached to a base plate, serves to protect the 
base material to give it long-term life and endurance. The combined 
constituents of the top coating provide good lubricity with low friction 
and excellent heat-resistance for repeated direct contact with hot glass. 
The composite material is adapted to supporting hot glass articles without 
marring or marking of the glass substrate, nor resulting in any pick up of 
residue which could deleteriously affect the appearance or structural 
strength of the glass articles. The coating is fully cured into a 
solidified thermoset condition and has no tackiness to detract from its 
usefulness over a wide range of elevated temperature applications. The 
silicone and organopolysiloxane resin constituents being essentially 
solventless do not emit vaporized solvents or create any other deleterious 
emissions in use as part of the composite material. 
Various modifications may be resorted to within the spirit and scope of the 
appended claims.