Note: Descriptions are shown in the official language in which they were submitted.
~ii4~8
FLEXIBLE CHEMICALLY TREATED FIBERS AND COATED FABRICS THEREOF
The present invention is directed to chemically treated bundles
of fibers such as strands or yarns which can be woven, where the woven
fabric finds particular application in bleing coated or laminated with
polymerlc films.
Chemically coated textile fabrics are manufactured by coatlng
or laminating polymeric film to a textile fabric substrate and they are
used in a wide variety of products. Early coated fabrics were cotton
fibers with coatings of wax, oil, or natural rubber that were applied to
render the material waterproof. With the advent of synthetic polymers,
the polymeric film applied to the textile fabrics included polyvinyl
chloride, polyurethane, silicones, polytetrafluoroethylene, polyethylene,
chlorosulfonated polyethylene, chlorinated polyethylene polymers of
ethylene propylene diene monomer, neoprene and synthetic rubbers such as
Hypalo~ rubber and nitrile rubber. Along with the development of
various polymeric films, the fibrous material comprising the textile
fabric was also revolutionized to include such fibers as polyesters~
polyamides such as nylon, aramid fibers such as Kevlar fibers, rayon,
graphite, and glass fibers and other organic and inorganic man made
fibers.
The coated textile fabrics have found a wide range of
applications from architectural and building applications to industrial
and commercial fabric applications and to geotextile applications. A few
building applications include air and tension structures like tension
and/or air supported covers for athletic stadiums and airport facilities
like the tent-roof 425,000 square meter coated fabric roof of an airport
facility and the 26.1000 square meter air-supported coated fabric roof for
an athletic stadium, while a few industrial and commercial applications
include reservoir, pool, pond and waste site covers and liners, awnings
~L2~i~998
and tarpaulins, and a few geotextile applications include road repair
-systems and other civil engineering applications. In these ranges of
various applications, many of the applications have common performance
requirements of the coated fabrics while some of the applications also
demand specific performance requirements of the coated fabrics. The
performance requirements are met by both individual and amalgamated
contributions of the uncoated textile fabric and polymeric film coating.
The performance requirements demanded from the textile fabric include
high tensile strength, good flexibility, good weatherability, good
chemical resistance, high tear strength, resistance to tear propogation,
good dimensional stability to minimize stretch under load, good stability
under various temperature and humidity conditions, good abrasion, and
good adhesion to the polymeric film. Another useful property of the
coated fabrics, especially for structure and building applications is
good flame resistance.
Some fibrous materials that can be used for polymeric coated
textile fabrics may be deficient in one or more of the desired
performance properties. For instance, inorganic fibers such as glass
fibers, have good dimensional stability, are nonflammable, and have a
good stiffness, but they lack the requisite flexibility, abrasion
resistance and adhesion to the polymeric film used to coat or laminate
the textile fabric. In addition, when glass fibers are used in preparing
the fabric for the coated fabrics, greige goods have traditionally been
used. In producing glass fibers, ordinarily an aqueous chemical treating
composition is applied to the filaments as they are attenuated from
molten streAms of glass issuing from a bushing of a glass melting
furnace. The filamlents are then gathered into strands and the strands
either twisted or untwisted are prepared into yarns. The greige goods
~2~;49~8
are prepared by weaving the glass fiber yarns and heat cleaning the yarns
to remove the chPmistry of the si~ing composition. The heat cleaning of
the glass fiber yarn may reduce some of the strength properties inherent
in the glass fibers, and, thereby, detract from the strength properties
of the glass fiber fabric. The deficiencies of the glass fibers may not
be assuaged by formulating composite strands including various types of
organic textile materials with the glass fibers. The fibProus materials
and polymeric films are used to produce coated fabrics typically having a
thickness of around 1 millimeter with a total mass per unit area in
excess of about 750 grams per square meter. The polymeric film in the
coated fabrics serves to impart air tightness, color and protection from
abrasive wear to the basic fabric. Even with the organic fibrous
materials used in the fabric, the chemical bonding between the coating
and the fabric is not very strong despite the inclusion of
fabric-adhesion promoters in the polymeric formulation comprising the
film.
It is an object of the present invention to provide fibrous
matèrials having improved flexibility and abrasion resistance to result
in improved coated or laminated fabric products.
It is an additional object of the present invention to provide
fibrous materials having improved flexibility and abrasion resistance to
result~in improved woven and unwoven fabrics which can be manufactured
into coated fabric products without requiring heat treatment of the
fibrous materials or fabric.
SUMMA~Y OF THE INVENTION
Accordingly, the aforementloned objects and other objects
gleaned from the following disclosure are accomplished by the bundles of
~2~ 8
sized filaments coated and impregnated w:Lth the moisture reduced,
partially cured residue of an aqueous cl~emical treating composition.
The aqueous chemical treating composition has an aqueous soluble,
dispersible or emulsifiable elastomeric ethylene-containing interpolymer
such as a copolymer or terpolymer formed from ethylene monomer and one or
more polar comonomers and a water soluble, dispersible or emulsifiable
PJefe~ ~b~
crosslinkable polymeric material. ~h~ethylene-containing interpolymer
has a glass transition temperature of at least as low as around O~C. and
has sufficient ethylene segments to achieve the desired glass transition
temperature and has one or more polar comonomers which result in an
essentially noncrystalline (amorphous) copolymer or terpolymer. The
interpolymer comprises the ma~or portion of the solids of the aqueous
chemical treating composition. Water is present in the composition in a
predominant amount so that the total solids and the viscosity are
effective for impregnating the bundle of filaments. The impregnation is
to such a degree so that the moisture reduced, partially cured residue of
the aqueous impregnant composition is present on a substantial portion of
a majority of the filaments in the bundle so that a majority of the
filaments are separated to some extent from each other. The
crosslinkable material is present in the aqueous chemical treatment in an
amount tha~ is effective to engender a partial cure of the molsture
reduced residue of the coating to provide a substantially nontacky
ex~ernal surface of the coated and impregnated bundle of filaments.
Optionally included in the aqueous chemical coating composition
are water soluble, emulsifiable or dispersible waxes, plasticizers and
diene-containing elastomers and crosslinking controlling agents. The
diene-containing elastomeric latex is ordinarily p-resent as an optional
constituent, except when the polar comonomer for the ethylene-containing
~26~g8
interpolymer is a comonomer which tends to co-crystallize with the
polyethylene crystal structure. In this case, the diene-containing
elastomer must be present in at least a minor portion of the solids of
the coating composition. The diene-contiaining elastomer is essentially
free of vinyl pyrridine.
The aqueous chemical treating composition is present to
impregnate the bundle of filaments, where the filaments have a dried
residue of an aqueous sizing composition. In the process of forming
filaments, the aqueous sizing composition is applied to protect the
filaments from interfilament damage, and, if necessary, it renders the
surface of the filament less hydrophilic to be more compatible with
hydrophobic coatings.
The impregnated bundle of filaments alone or in combination
with other bundles of filaments has sufficient flexibility for weaving of
the bundle or bundles into a fabric. The fabric can then be coated to
produce coated fabrics by processes such as impregnation, saturation
processes, and surface coating processes like solvent-containing
coatings, or plastisols and lamination with preformed films or sheets of
the coating polymeric materials.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts the coated fabric showing the laminated sheets
or films used in conjunction with the fabric.
_ET~ILED DESCRIPTION OF THE IN~ENTION
Bundles of filaments, strands, rovings and bundles of strands
and yarns both twisted and untwisted that are flexible enough to be woven
can be produced accDrding to the present invention without the need for
~2~
heat cleaning the bundles to remove chemical treatments. Ordinarily when
glass filaments are produced usually as continuous fllaments, the
filaments are treated with a sizing composition which has chemical
components to protect the filaments from interfilament rubbing and
friction and from friction and rubbing developed in processing the
filaments over various contact points and guide eyes. In weaving fabric
or cloth from the continuous fibers or group of fibers as strands or
group of strands or yarn, the length-wise running yarns in the woven
fabric or warp yarn can be subjected to considerable abrasion from the
moving parts of the weaving loom. Abrasion to the warp yarn can result
from guide surfaces of split rods, drop wires, confuser bars, heddles,
reeds, shuttles and ad~acent yarns in the loom. To protect the warp yarn
from such abrasion, a slashing chemical composition is usually applied.
Once the fabric is woven, the fabric has the warp yarn that has present a
sizing composition present on the filaments from their formation and a
slashing sizing composition, while the weft yarn in the fabric has
present only the forming sizing compositioa. The additional coating of
the slashing size on the warp yarn would result in different surface
properties between the warp and weft yarns in the same fabric. Such
differences would cause imperfections in drying of the fabrics or in the
handle and feel of the fabrics or in the electrical and reinforcement
properties of the fabrics used with polymeric coatings. Therefore, the
fabrics are usually heat cleaned to remove both the forming and slashing
sizing compositions and to set the yarns ln the fabric. For example,
with glass fiber strand yarn fabrics, this heating is usually conducted
at temperatures of around 900 to 1300F (482 to 705C) for around 10 to
180 seconds or longer to volatiliæe the solids and remove them from the
fabric and to soften the glass fibers in the fabric to set them in their
~;2~
new positions. Glass fiber strands ordinarily have high tensile
strength, dimensional stability and resistance to chemical, photochemlcal
and microbiological degradation but the heat treating process reduces
somewhat the strength properties of the glass fiber strands.
Filaments such as polyester and nylon and Kevlar polyamides
have been used to make fabrics which can subsequently be coated with a
polymeric film or laminate. The glass fiber strand yarns do not have the
flex fatigue properties and the lighter density of the polyester and
polyamide yarns. A more flexible bundle of filaments, particularly glass
filaments, strands and yarns and even polyesters and polyamides are
provided by the impregnated bundle of filaments of the present
invention. The impregnated bundle of filaments has improved breaking
strengths and flex fatigue resistance and maintains these properties
under humidity and water aging and also provides good adhesion to the
polymeric film coating matrix.
The bundles of sized filaments of the present invention have an
impregnant of a moisture-reduced, partially cured residue of an aqueous
impregnant composition. The aqueous coating has a predominant amount of
the solids comprised of an elastomeric ethylene-containing interpolymer.
The interpolymer, which is usually a copolymer or terpolymer, is formed
from ethylene monomer and one or more polar comonomers, where the
comonomer may vary from co-crystallizing with the polyethylene crystal
structure or resulting in an essentially noncrystalline (amorphous)
interpolymer. Nonexclusive examples of these polar comonomers include:
vinyl acetate, methyl acrylic acld, ethyl acrylic acid, styrene, alpha
methyl styrene, methyl methacrylic acid, acrylamide, methyacrylic acid,
n-methyl-n-vinyl acetamide, diethyl fumarate, diethyl maleate, n-vinyl
pyrrolidone, n-viny:L succinimide and the like and mixtures thereof. The
~2~9~8
interpolymer has a ratio of the ethylene to the polar comonomers
sufFicient to have a glass transition temperature (Tg) of around 0C. or
less. The glass transition temperature can be determined by any method
known to those skilled in the art, examples of which include nuclear
magnetic resonance peak ratio or by approximation hy less complicated
techniques such as differential thermal analysis. The interpolymers
should be uniform interpolymers rather than nonuniform or alternating
copolymers or terpolymers although the latter two types may be used to a
limited extent. The uniform interpolymers are those that are formed
either from two or more monomers having equal reactivities polymerized to
àny conversion percent or by limiting the percent conversion during
interpolymerization to a low percent conversions when the monomers have
different reactivities so that the comonomer concentration is kept almost
constant. The nonuniform copolymers and alternating copolymers are those
known to those skilled in the art. The interpolymers are also water
soluble, emulsifiable or dispersible with the use of suitable emulsifiers
and/or solvents. The interpolymers can be produced by any method known
to those skilled in the ethylene copolymer art. A particularly useful
elastomeric ethylene-containing interpolymer is an ethylene vinyl acetate
copolymer having the vinyl acetate monomer present in the copolymer in an
amount in a range of around 25 mole percent or greater or about 45 to 80
weight percent of the copolymer. The copolymer also has a sufficient
amount of ethylene comonomer to give a Tg for the ethylene vinyl acetate
copolymer of 0C. or less. A nonexclusive example of such an ethylene
vinyl acetate copolymer is that commercially available from Air Products
and Chemicals, Inc. in an emulsion form under the trade designation
Airflex 410 vinyl acetate/ethylene copolymer emulsion. This material
has the copolymer formula of Ax-By where A is equal to C4H602
9~3
and B is equal to C2H4. The appearance of the emulsion is a white
mobile liquid having a viscosity of 100 to 2,000 as maasured by
Brookfield viscosimeter, Model LVF (No. 2 or No. 3 spindle at 60 rpm and
at 77F). Also the emulsion has a pH of 4 to 7 and a percent volatiles
by volume of 45 to 53 and a specific gravity of 1.1 and a density of 9
pounds per gallon. The dispersion has very small polymer particles in
water and contains formaldehyde at concentrations of up to 0.1 percent by
weight with no other photochemically-reactive solvents or reactive
chemical solvents added. The residual unpolymerized monomer levels are
less than 0.5 percent of the total product. The amount of the
ethylene-containing interpolymer present in the aqueous lmpregnant
composition is is an effective film forming amount for impregnating the
bundle of filaments to produce a near continuous film on a substantial
portion of the surfaces of the filaments in tha bundle of filaments.
Also the amount may be effective to form a film on the bundle of
filaments. Generally, the amount is a predomiant amount of the solids of
the aqueous impregnant composition.
The aquaous chemical impregnating composition in addition to
the ethylene-containing interpolymer has one or more crosslinkable
materials. Suitable crosslinking materials are chemical compounds,
monomers, oligomers and resinous type polymers all of which are at least
self-crosslinkable at ambient or elevated temperatures and at atmospheric
or sub or super-atmospheric pressures. By self-crosslinkable, it is
meant that the material need not crosslink with the ethylene-containing
interpolymer. l`he polymeric crosslinking materials may bel
self-crosslinkable through external chemical compounds or through
internal crosslinking. By externally crosslinkable, i~ is meant that
corsslinking agents known by those skilled in the art for particular
_ g _
~2~9~3
resinous polymers can be used to crosslink the polymer. Resinous
polymers include such polymers as epoxies, methylol-condensate polymers,
polyurethanes, polyesters and other polymers that are not rubber polymers
as are butadiene, isobutylene, styrene-butadiene-vinyl-pyrrldine
terpolymers and styrene-butadienP copolymers and the like. Nonexclusive
examples of the crosslinkable materials include the aldehyde condensate
polymers such as melamine formaldehyde, hexakis/methylol-containing
condensates, monomers, dlmers, trimers and hi8her oligomers, where for
the phenol or resorcinol, compounds include cresol and mixtures of its
isomers, xylenol or mixtures of its isomers, a mixture of homologs of
phenol and dihydric phenols such as phlorglucinol, resorcinol,
cresorcinol, and meta-xylorcinol can be used. The aldehyde includes any
methylene donor that can be used in lieu of formaldehyde, for example,
paraformaldehyde, hexamethylene-tetramine, acid aldehyde, furfural and
m~xtures thereof. The aldehyde or methylol condensates can be used in
conjunction with acid or basic catalysts. Also internal curing may also
occur as the result of removal of a stabilizing ingredient. For example,
polyvalent metal ions can be stabilized by the addition of volatile
complexing agents. ~hen the impregnant is appplied, these agents
evaporate, allowing the metal to bond at two or more sites on the polymer
resulting in a crosslinked coating. An example of this would be the use
of zinc or zirconium salts which are stabilized by the addition of excess
ammonia. When an impregnant is applied, the ammonia evaporates resulting
in a flexible cross:Linked impregnant. This same principle can be used to
inactivate a catalyst. For example, toluene sulfonic acid which is used
to catalyze curing with urea-formaldehyde resins can be inactivated with
a volatile amine. When the impregnant is applied the amine-acid complex
is decomposed through volatilization of amine and the coating is cured.
-- 10 --
12~;~9~
It is preferred to have one or more melamine formaldehyde resins because
of thelr ease in crosslinking and their compatibility with the
ethylene-containing interpolymer. A particularly suitable melamine
formaldehyde resin is the aqueous melami~e formaldehyde resin available
from ~Ionsanto Company under the trade designation Resimene 841 which has
less than two percent free formaldehyde and less than 5 percent methanol
and has a boiling point of 210F. The Resimene 841 also has a vapor
pressure of 95 for methanol and 17.5 for water, a vapor density of 1.11
for methanol and 0.64 for water, a colorless, clear mobile liquid
appearance, specific gravity at 77F. of 1.25 and a percent volatile by
volume percent of 29.
The amount of the crosslinkable material used in the aqueous
impregnant composition is an effective amount to produce at least partial
curing of the moisture reduced residue of the aqueous impregnating
composition. The partial curing controls the surface tack of the
moisture-reduced residue of the impregnant to enable a nearly uniform
payout of the impregnated bundle of filaments from wound packages, where
the bundle of filaments is comprised of larger diameter filaments~ the
partial curing by crosslinking can be reduced. Where the bundle of
filaments has the finer diameter filaments, the partial curing can be
increased from that for larger diameter filaments. Where the impregnated
bundles of filaments are packed more densely on a wound package, the
bundles will be mor~e tack sensitive and a higher degree of partial curing
through crosslinking is desirable. ~ith such a controlled surface tack
characteristic, the bundle of filaments impregnated with the aqueous
impregnant composition in a moisture-reduced state can be processed on
weaving looms without the use of loom feeders. Although if loom feeders
are available, the partial curing can be reduced so that surface
~2~9~8
tackiness is not controlled as stringently. Preferably, the partial
curing results in a hardness or modulus of the moisture-reduced residue
of the aqueous impregnant composltion impregnating the bundl~ of
filaments so that the flexibility of the impregnated bundles of filaments
has at least a two-fold improvement in f:Lexibillty. The improved
flexibility is over a similarly constructed, unimpregnated bundle of
filam~nts. In addition, the partial curing permits further curing of the
moisture-reduced residue of the aqueous impregnant composition
impregnating the bundle of filaments. The further curing provides
chief]y for external adhesion between the bundles of filaments and the
polymeric film coating that subsequently will be applied to the fabric of
impregnated bundles of filaments. Also some further additional internal
adhesion may be provided to increase further the integrity of the bundle
of filaments already provided through partial curing. An upper limit on
the extent of partial curing through crosslinking is in order that the
flexibility of the impregn~ted bundle of filaments is not reduced below
the flexibility of unimpregnated bundles of f ilaments.
In addition to the crosslinkable material, the aqueous
impregnant composition can have a crosslinking controlling agent to
control the de~ree of crosslinking of the self-crosslinkable material and
possibly between the self-crosslinkable material and the
ethylene-containing interpolymer. The crosslinking controlling agent can
be one which modifies the p~ of the coating composition such as ammonium
hydroxide, or can be one such as an acid catalyst for the crosslinkable
material. A nonexcLus-lve example of the latter is a solution of toluene
sulfonic acid in isopropanol such as that available under the trade
1 ~ >~cl rk
daci~ i4* Cycat 4()40 with 40 percent acid and 60 percent alcohol
available from Amer:Lcan Cyanamide Co. In addition, ln the absence of a
- 12 -
~L26~9~3
crosslinking controlling agent, one of the monomers in the
ethylene-containing interpolymers can provide for a less tacky film
coating by its concentration in the interpolymer to increase the
softening point of the interpolymer. Also the ~rosslinking controlling
agent may assist in controlling the hardness or modulus of the film of
the coating. The amount of the crosslinking controlling agent used in
the aqueous impregnant composition will vary depending on the strength of
controlling agent, but the amount is gauged in conjunction with the
amount of the crosslinkable matQrial to achieve partial curing of the
residue of the aqueous impregnant composition.
The water in the aqueous chemical treating composition
constitutes a predominant amount of the composition including both the
volatile and the nonvolatile portions. The amount of water results in a
total solids concentration and viscosity for the composition that enables
the composition to impregnate the bundle of filaments including bundles
of strands and yarn. The degree of impregnation of the bundle of
ilaments is such that a majority of the filaments have a substantial
portion of their surfaces covered with a near continuous film of the
residue of the aqueous impregnant composi~ion so that a majority of the
filaments are separated from each other. It is not necessary that the
bundle is encapsulated, although it may be as long as it is also
impregnated. Preferably, where the ethylene-containing interpolymer is
present as an emulsion or dispersion having a solids content of around 50
percent, the viscosity of the aqueous impregnant composition is around 5
or less for a kiss roll type coating application and up to around 10 ~ 5
centipoise at room temperature for a die coating process. The total
solids of the aqueous impregnanT~ composition varies depending upon the
diameter of the filaments in the bundle. The variation is that the finer
- 13 -
~6~
diameter filaments require a higher total solids in the aqueous chemical
treating composition, since the surface area of the finer diameter
filaments is hig7ner.
In addition, an optional component of the aqueous chemical
coating composition can be one or more alqueous emulsifiable or
dispersible waxes. The type and amount of wax is that which is effective
to serve as an adhesion promoter for the matrix coating that will be
applied to fabrics made from the flexible bundle of filaments. In
addition, the type and amount of wax can be effective to provide a screen
effect against ultraviolet degradation when the fabric or polymer coated
fabric is not protected from the weather or the envlronment. Also the
wax may modify the frictional properties of the impregnated bundles of
filaments. The one or more waxes can be dispersed or emulsified in water
with any suitable emulsifiers known to those skilled in the art. The one
or more waxes can be included in the aqueous impregnant composition in a
preemulsified or predispersed form. The preferrad wax materials are the
microcrystalline wax materials and suitable examples of commercially
available predispersed forms include Polymekon SPPN-40 microcrystalline
wax available from Petrolite Corporation-~areco Division, Tulsa,
Oklahoma. This material is a hydrocarbon water dispersion with a 40
percent solids. Another suitable example is Mobilcer Q microcrystalline
wax available from Mobil Chemical Company. This material is an acid type
aqueous emulsion of microcrystalline wax, where the wax has a melting
polnt of 160F, and where the emulsion has an average particle size of 2
micron, and a solids content of 50.5 percent by weight, and an emulsion
density of 7.9 and a pH of 6.8. Preferably the amount of wax present in
the coating composition is in the range of up to about 5 weight perc~nt
of the aqueous impregnant composition. Any suitable solids and
~r~aC~ a~k
L9~8
dispersants or emulsifiers having a suitable HLB value as known to those
skilled in the art can be used to assist in emulsifying or dispersing the
wax in water.
Also the aqueous impregnant composition can have one or more
plasticizers which are soluble, emulsifiable or dispersible in water,
The plasticizers are added in an effective amount to provide some
plasticity to the ethylene-containing interpolymer. Preferably the
amount of plasticiæer present in the aqueous impregnant composition would
be in the range of up to about 5 ~eight percent of the aqueous impregnant
composition. The plasticizer is used, where the Tg of the interpolymer
does not result in adequate flexibility of the impregnated bundle of
filaments, to reduce the Tg and to achieve a more flexible impregnated
bundle of filaments. Any suitable solvents and emulsifiers or
dispersants having suitable HLB values as known to those skilled in the
art can be used to emulsify or disperse the plasticizer in water. These
emulsifiers can be nonionic, cationic or anionic and a particularly
useful type of an emulsifier is the nonionic emulsifier such as
polyoxyalkylene sorbitan monolaurate, commercially available under the
,~ ;na~
b trade-~_}~}_Y-~-tTween 21 emulsifier from ICI America. It is preferred
that the plasticizers used should be flame retardant type plasticizers
such as xylene triphosphate available under the trade designation
Phosphlex 179 -A plasticizer available from Stauffer Chemical Company.
This material is a liquid with a specific gravity at 20/20C of 1.143, a
density of pounds per gallon of 9.5, a boiling point at 10 millimeters of
mercury of 265-2~5C, a pour point of 0F, a viscosity at 100F SUS of
220 and a flashpoint of 455F COC. Also a phosphite chelator such as
nonylated phenol phosphite can be emulsified or dispersed in the aqueous
impregnant composition or preemulsified or predispersed and added to the
~L2~
aqueous impregnant composition. A suitable phosphite chelator is that
~1 cl r~ ~
which is available under the trade ~ig~ sR Mark 1178 from Argus
Chemical Corporation, Brooklyn, New York. This material has a specific
gravity of 0.99, and 0 percent volatiles. Another type of commercial
plasticizer that could be used is an epoxidized soy bean oil like that
~ rerh
commercially available under the trade-~-t}~176i=s Drapex 6.8 material.
Any other aqueous soluble, emulsified or dispersible plasticizer known to
those skilled in the art can be used in an effective plasticizing amount
for the ethylene-containing interpolymer.
The aqueous treating composition can have present a
diene-containing elastomeric polymer in conjunction with the
aforedescribed ethylene-containing interpolymer. The diene-containing
elastomer is water dispersible or emulsifiable with suitable solvents and
emulsifiers known to those skilled in the art of elastomeric latices.
This elastomeric material is preferably added to the aqueous impregnant
composition as a latex in an effective flexibilizing amount to assist in
flexibilizing the moisture reduced, partially cured residue of the
aqueous lmpregnant composition to the desired flex modulus. Preferably
the modulus at 100~ elongation of a cast film of the aqueous impregnant
composition is in the range of about 200 to 8,000 psi and most
preferably, about 800 to about 5,000 psi. Such an aqueous impregnant
composition when moisture-reduced and partially cured as an impregnant in
the bundle of filament provides the desired flexibility. The amount of
the elastomeric latex that is used is always an amount that will not
interfere with the compatibilizing amount of the ethylene-containing
interpolymer for compatibility with the polymeric matrix coating that
subsequently coats any fabrics prepared from the flexible bundle of
filaments. When the ethylene-containing interpolymer has present a polar
~2~ 8
copolymer which reduces the noncrystallinity of the interpolymer or
increases the Tg of the inte}polymer, the diene-containing elastomeric
latex must be present in the coating composition. The diene-containing
elastomeric latex is preferably essentially free of any vinyl pyrridine
monomeric or repeating units in the polymer. The vinyl pyrrid1ne tends
to make the elastomer coo stiff for increasing the flexibility of the
moisture reduced, partially cured residue on the flexible bundle of
filaments.
Nonexclusive examples of suitable diene-containing elastomers
include: polybutadiene homopolymer, and carboxylated styrene-butadiene
copolymers or any other non-selfcrossl~nkable elastomer. The term
non-selfcrosslinkable as used herein refers to a polymeric material that
cannot undergo intramolecular or internal crosslinking with itself but
can undergo intermolecular or external crosslinking with other
materials. The intramolecular crosslinking means one part of the same
molecule or polymeric chain crosslinks with another part of the same
molecule or chain. Here, the term "chain" includes the polymeric
backbone chain and pending groups. Suitable examples of
non-selfcrosslinkable elastomers include: elastomeric reaction products
formed by the reaction of 1,3-diene hydrocarbon monomers such as
butadiene-1,3; isoprene; 2,3-dimethyl-1,3-butadiene,
2-2ethyl-1,3-butadiene and the like alone as homopolymers or in mixtures
as interpolymers; or ethylene-propylene-diene rubbers (EPDM) produced in
a suitable manner ~rom such dienes as dicyclopentadiene,
5-ethylidene-2-norborene, 1,4-hexadiene,5-methylene-2-norborene
lnterpolyermized wLth ethylene and an alpha-mono-olefin having from 3 to
20 carbon atoms such as propylene; nitrile rubber such as nitrile
butadiene latex; or butyl rubber which is a commercial name for
~ 17 -
copolymers of isobutylene wlth small amounts of butadiene or isoprene or
mixtures thereof. Another elastomer that may be used is chloroprene or
neoprene. All of these elastomeric materials are preferably used in
their latex form. The diene-containing elastomeric latex is always
present in the aqueous impregnant composition when the polar comonomers
for the ethylene-containing interpolymer is vinyl chloride, carbon
monoxide, and vinyl fluoride. When poly'butadiene homopolymer latex or
similar materials are used, the amounts can range from less than 20
percent to greater than 40 percent based on the ethylene-containing
interpolymer ilt the aqueous impregnant composition. ~mounts less than 20
percent give diminished benefits in flexibility as the amount approaches
0. Amounts greater than 40 weight percent provide adequate flexibility
but increase the amount of tackiness of the moisture-reduced, partially
cured residue on the bundle of filaments. If alternative measures are
not pursued in reducing such tackiness, then the amount of polybutadiene
homopolymers should not be too much greater than 40 percent in order to
maintain the less tacky nature of the impregnated flexible bundle of
filaments. To assist in maintaining a less tacky nature to the film, the
amount of styrene in a carboxylated styrene butadiene copolymer can be
iucreased. Increasing the amount of styrene from about 60 weight percent
to about 84 weight percent is an example of an approach to decreasing the
tackiness of the resultant residue.
nonexc:Lusive example of a commercially available
diene-containing e:Lastomer latex that can be used includes a
1,3-polybutadiene homopolymer latex available under the trade ~e~}rRhLL~
"LPM-6290" from Goodyear Tire and Rubber Company having a total solids of
43 to 46 percent, a pH of 8 to 9.5, a maximum viscosity of 6,000
centipoise (RFT 1 at 20 rpm), a maximum coagulum of 0.05 percent max and
~Z~99~
a mechanicfll stability of 55 to 75 milligrams and surface tension of
around 58 to 74 dynes per centimeter, and particle size in the range of
500 to 2,000 angstroms and a maximum gel content of 25 percent. Other
nonexclusive examples of non-selfcrosslinkable elastomeric latices are
those available from Polysar in Monaca, Pennsylvania under the trade
~Lo.y~c~Li~ Dylex latex 55E having a percent volatiles by volume of 49 to
51 and a formula of C7H6 = CH2 + C4H6 ~ CCHO2, and the
Polysar carboxylated styrene butadiene latex having 84 percent styrene
content.
The aqueous impregnant composition having present the
ethylene-containing intarpolymer and self-crosslinking material and water
need not have pres~nt all of the optional ingredients such as the wax,
plasticizer, and diene-elastomer except in regard to the presence of
certain polar comonomers in the ethylene-containing interpolymer as
aforementioned, and any pigments and~or dyes known to those skilled in
the art of coloring textiles. It is preferred, when the diene
elastomeric latex essertially free of vinyl pyrrldine is not present,
that the aqueous impregnant composition with the ethylene-containing
interpolymer and self-crosslinking material and water also has present
the crosslinking controlling agent as ammonium hydroxide, one or more
dispersed waxes and one or more dispersed plasticizers. When the
diene-containing elastomeric material essentially free of vinyl pyrridine
is present in the coating composition, it is preferred to have present
only one of each of the dispersed microcrystalline wax and dispersed
plasticizer.
The aqueous impregnant composition can be prepared by adding
all of the components sequentially or simultaneously to the desired
volume of water with appropriate emulsifiers for any of the materials to
-- 19 --
be emulsified or dispersed in water. Preferably, the materials that are
not water soluble are preemulsified or dispersed with suitable solvents
and emulsifiers with appropriate HLB values as known to those skilled in
the art and added to formulate the aqueous impregnant composition. ~ost
preferably, the aqueous dispersion of the ethylene-conta-lning
interpolymer has added to it the aqueous dispersed plasticlzer6 and the
aqueous dispersed waxes. The self-crosslinking material in an aqueous
medium is diluted and has added to it the ammonium hydroxide for
controlling the rate of cross-linking, and this mixture is added to the
aqueous mixture of interpolymer and plasticizer and/or wax. The
diene-containing elastomeric latex is preferably added to the aqueous
medium of the self-crosslinking material before it is added to the
aqueous mixture of interpolymer, plasticizer and/or wax. The aqueous
coating can be further diluted with water to achieve a desired volume of
material to give the aqueous impregnant composition the total solids and
viscosity required for impregnating the bundle of filaments.
The aqueous impregnant composition is applied to bundles of
sized filaments, which includes bundles of strands, yarns both twisted
and untwisted and bundles of monofilaments. The filaments have been
sized during their formation to protect the filaments and to make them
compatible with hydrophobic mater.als. When the filaments are glass
fibers, the sizing is an aqueous sizing composition which has present at
least a coupling agent to make the fibers less hydrophilic and a
protectorant. The protectorant can be an aqueous soluble, dispersible or
emulsifiable glass Xiber lubricant or an aqueous soluble, dispersible or
emulsifiable glass Xiber film forming polymer. Any coupling agent, glass
fiber lubricant or glass fiber film forming polymer known to those
skilled in the art can be used. It is preferred that the slzed glass
- 20 -
~12fi4~
filaments are essentially free of a starch film forming materials. A
nonexclusive example of a suitable nonstarch containing aqueous sizing
composition for glass fibers is that disclosed in IJ.S. Patent 4,390,647
(Girgis). The application canbe by dip coating or die coating or
any other process known to those skilled in the art for applying
coatings to groups of filaments. ~or example, the bundle of filaments
can be dipped into a bath containing the aqueous impregnating
composition or the bundle can contact a kiss roll or other applicator
device that carried it to contact the bundle of filaments. Also a
die coating arrangement can be employed, where the bundle of
filaments is pulled, pushed or stuffed through permanent or adjustable
orifices. This operates effectively to open the strand immediately
in advance of the orifice to expose the innermost regions of the
glass fiber bundle to the liquid impregnant located in the container
with the orifices. Before the bundle contacts the impregnant, it can
ride over a bar or similar device under tension to spread the fibers in
the bundle for maximum separation and better impregnation. The sized
filaments have ~he sizing composition which does not provide too much
integrity between the filaments when they are gathered into groups or
bundles of filaments so that upon dip coating or die coating, the
filaments separate somewhat one from the other to assist in allowing the
coating composition to surround and enter the groups or bundles of
filaments. The impregnation preferably is to a degree so that every
filament in the bundle or in bundled strands has a substantial portion of
its surface covered with the aqueous impregnant composition so that when
the aqueous impregnant composition is dried and partially cured, the
filaments in the bundles will be separated from each other.
- 21 -
~2~ 98
The bundles of filaments with the treatment of the aqueous
impregnflnt composition are dried to partially cure and reduce the
molsture content of the aqueous impregnant composition. Any method known
to those skilled in the art for curing crosslinkable materials may be
used to dry and cure the impregnated bundle of filaments. It is
preferred that the drying is a non~dielectric type drying and that the
moisture is reduced to a moisture content in the range of less than
around 1 to about 2 percent of the bundle. This and the partial curing
are accomplished by drying at suitable temperatures and times to result
in the desired moisture reduction and partial cure. Preferably, the
drying is conducted at a temperature in the range of about 400F to about
500F (200-260C) for a time in the range of about 10 seconds to about 60
seconds or any equivalent temperature and time relationship to accomplish
a similar degree of moisture reduction and part~al curing.
The parti211y cured impregnated bundle of filaments is flexible
enough to undergo myriad fabric producing processes. Nonexclusive
examples of fabric producing processes include weaving; nonwoven fabrics,
knitted, braided, weft-knit fabrics such as those produced on the ~ayer
or Libya weft insertion fabric machine. On this type of machine, the
fabric is a bi-directional crosslaid warp and weft structure, where the
weft yarns do not interlace as in traditional woven fabrics. A "knit
stitch" is run ln the warp machine direction to lock the fabric
together. For the weaving operation, plain weave, satin weave or any
other type of weaving for producing a fabric as known to those skilled in
the art can be used.
The fabric whether woven or nonwoven or knitted or braided can
be coated with numerous types of coatings by myriad processes. Examples
of suitable polymeric coatings include vinyl resins such as polyv~nyl
- 22 -
a
chloride, polyethylene and ethylene copolymers, polyurethanes, phenolic
reslns, melamine formaldehyde resins and elastomeric materials such as
chlorosulfonated polyethylene, chlorinated polyethylene and polymers of
ethylene propylene diene monomers and Hypalon~ elastomers and silicone
polymers.
These types of polymers can be coated onto fabrics of the
flexible bundle of filaments by impregnation or saturation processes and
surface coating processes such as solvent-containing coatings and 100
percent solids coatings and lamination processes of preformed films or
sheets. For example, when a plastisol 100 percent solids coating is
used, an application of a first coating of poly(vinylchloride) latex is
applied to the fabric to improve adhesion of subsequent plastisol
coatings. After the application of the plastisol coating paste to the
fabric, the fabric is heated to a temperature usually around 350 to 400F
to permit the resin particles to form a continuous phase over the fabric
and to actually contact in the interstices between the fabric. The
polymeric coating then cools to a tough coherent film at room
temp~rature. The fusion process is so quick that the coated fabrics may
be cooled as soon as the required fusion temperature is obtained. In
addition to the polymeric material, various pigments or fillers can be
included and th~ polymeric materials may be modified by plasticizers and
solvents.
The polymeric coating and preferably the polyvinyl chloride
coating also can be applied by other coating processes known to those
skilled in the art such as passing the fabric over a knife-over-roll
coater. Also any wet coating process known to those skilled in the art
can be used such as passing the fabric over sequential knife coaters or
through a floating knife coater with a support channel. Also blanket
- 23 -
~Z64~9~
knife coaters and inverted knife coaters and levelon coaters with reverse
smoothing rolls can be used as can engraved-roll or rotogravure coating
units. In applying the plastisols, any clry or 100 percent solids coating
process known to those skilled in the art can be used. For instance, hot
melt coating can be used or any modified wet coating process, where there
is not any solvent evaporation. In addition, cast-coating techniques can
be used as well as metal-belt precast coaters. Also a dry powder resin
coating method such as hot calendar-coatlng and extrusion-coating can be
used. Also wet lamination and dry lamination involving the union of the
fabric with a film or sheet of the polymer, which has been formed in a
separate operation, can be used. In the lamination processes, the film
or sheet can be formed by calendaring, by extrusion, or by casting in a
separate operation and laminated to the fabric base. With these
proçesses and adhesive coating can be applied to the plastic sheet prior
to the application of pressure against the fabric and plastic sheet or
the plastic sheet ~an act as the thermoplastic adhesive itself and can be
heated to produce the adhesion and afterwards brought into contact with
the fabric while hot. The use of the adhesive application is performed
in the multiple-ply drum lamination process. Also with foamable
polymeric materials, the thermoplastic foam lamination process can be
used.
Figure 1 depicts a coated fabric of the present invention where
numeral 12 shows the fabric comprised of the flexible impregnated bundle
of filaments of the present invention and numerals 11 and 13 indicate the
polyvinyl chloride sheets or films that are laminated together
sandwiching the fabric in between the laminate sheets. Ordinarily, the
thickness of the coated fabric ranges from even less than 0.010 to
greater than 0.06 inch~(.025 cm - .15 cm), and the amount of coating on a
- 24 -
~LZ&~
unlt area of the fabric varies widely but it is usually around 5 to about
50 ounce/yard2 (119-1700 gm/m ).
PREFERRED EMBODIMENT
In the preferred embodiment of the present invent-Lon, the
filaments are glass fibers of any fiberizable glass composition such as
"E-glass", "621-glass", "A-glass", "C-glass", and "S-glass", and any low
or free boron and/or fluorine derivatives thereof. The most preferred
glass composition is the 'l621-glass". The glass fibers are formed by
attenuation from molten streams of glass issuing forth from orifices in
a bushing of a glass batch melting furnace. After the filaments have
cooled below the boiling point of water, an aqueous sizing composition is
applied to the fibers. The aqueous sizing composition is a nonstarch
textile size having a 50/50 blend of a polyalkylene polyol available
under t'ne trade mark Pluracol V-7 polyol and polyoxyalkylene
polyol available under the trade mark Pluracol V-10 polyol from
BASF Wyandotte. The amount of the blend is in the range of about 0.5 to
about 5 weight percent of the aqueous treating composition and most
preferably about 1 to about 3 weight percent. The silane coupling agent
is preferably a lubricant modified amino silane coupling agent available
under the trade mark Y-9072 silane. This material is present in
an amount in the range of about 0.01 to about 2 weight percent of the
aqueous treating composition. The preferred cationic lubricant is the
polyamine lubricant commercially available as an acidified cationic fatty
acid amide under the trade mark Emery 6760-U. This material is
present in the aqueous treating composition in an amount of about 0.01 to
about 4 weight percent of the aqueous treating composition. The total
solids of the aqueous treating composition can be any convenient solids
- 25 -
range for sizlng compositions to be applied at a proper and desired LOI
to glass fibers. Preferably the total solids is in the range of around 3
to arolmd 20 weight percent. It is preferred to apply the aqueous
treating composition to the glass fibers in such a manner to give an LOI
for the glass fibers in the range of about 0.1 to about 1 percent and
most preferably about 0.5 to about 0.8 percent.
The glass fibers treated with the aqueous nonstarch sizing
composition are gathered into one or more strands preferably one strand,
where the filam~nt diameter can range from less than 5 microns to around
30 microns, but most preferably is in the range of around 5 microns to 15
microns. The strands are collected on forming packages and dried to
reduce the moisture content of the aqueous sizing composi~ion to around
0.1 to about 1 weight pèrcent. One or more strands are coated with an
aqueous impregnant composition having the followlng formulation:
Air Flex 410 (vinylacetate/ethylene copolymer) 109000 g
(Air Products)
Water 6,500 g
Polymekon SPPW-40 (microcrystalline wax) 400 g
(Petrolite Corporation - Bareco
Division)
Mark 1178 ~nonylated phenol phosphite)50 g
(Argus)
Tween 21 polyoxyethylene sorbitan monolaurate 50 g
(ICI Americas)
Phosflex 179 (xylene triphosphate) 500 g
(Monsanto)
Myr~ 52 (polyxoyethylene stearate)75 g
(ICI Americas)
Resimene (melamine formaldehyde resin)500 g
(Monsanto)
Dylex D-55E (carboxylated SBR latex)1000 g
(Polysar)
- 26 -
ater To result in a percent
solids of 18 percent
The aqueous sizing composition has a pH of 8.5 + 0.5 and a viscosity of 4-5
centipoise.
The coating is performed preferably ln a die coater and
alternatively in a dip coating process. The total solids of the aqueous
impregnant composition is in the range of around 8 to about 35 weight
percent, most preferably around 15 to 35 weight percent. The coated
bundle of fibers are dried to reduce the moisture content and to
partially cure the aqueous impregnant composition which had a viscosity
of around less than 10 centipoise at room temperature. The temperature
of drying is in the range of 425 to 500~ (218 - 260C) for a period of
time of 10-60 seconds. The amount of the dip coating on the bundle of
filaments and impregnated into the bundle is around 4 to about 35 weight
percent and most preferably around 9 to 30 weight percent depending on
the fiber diameter of the glass fiber bundle. The coated bundle was
collected as zero twist material and woven into a fabric. The material
was then coated with a polyvinyl chloride plastisol coating in a
calendaring process. The fabric is coated first with a very thin film of
the vinyl plastisol under proper tension to set the weave structure.
Several passes are made of this coated fabric through the coating line to
accumulate a continuous film of about .02 (.05 cm) to about .04 (.1 cm)
thick of polyvinylchloride polymer. The coated fabric is cured at around
260F (127C) under pressure for a few minutes, cooled to ambient
temperature and pacl;ed on a roll.
The present invention and additional embodiments are further
illustrated by the following examples.
- 27 -
12~
Table 1 presents data on 11 aqueous coating formulations which
werP applied to sized glass fibers. The glass fibers had a filament
diameter of around 13 microns (K-fibers). The fibers were sized with an
aqueous sizing composition having a 50/50 blend of the polyalkylene
polyol V-7 polyol and polyoxyalkylene polyol V-10 polyol in an amount of
758 grams for each in a 10 gallon mix. The polyoxyalkylene polyol was
diluted with agitation with deionized hot water in an amount of around 50
percent of the total water used in the size. The hot water was at a
temperature of around 140-160F t60-71C) with agitation in a premix
tank. The mixture was agitated for 10 minutes and the solution was clear
and the polyol was added to a main mix tank. The 758 grams of the
polyalkylene polyol were added directly to the main mix tank. Hot
deionized water in an amount of around 20 percent of the total water in
the aqueous sizing composition was added to a premix tank and the glass
fiber lubricant was added in an amount of about 290 grams and agitated
for around 10 minutes and the mixture was transferred to the main mix
tank. The lubricated silane was added in an amount of 290 grams to the
main mix tank. The aqueous sizlng composition was then diluted to the
final volume of 10 gallons with deionized water and agitated for around
10 minutes before sampling. These fibers were then treated with the
aqueous impregnant compositions of Table 1 in a dip coating process and
the coated bundles uf filaments were constructed into a K-lS 1/0 product,
where one bundle had aro~md 1,000 filaments.
In addition to the strand constructions of the preferred
embodiment, a bundle construction of G-75 5/0 strands can also be
utilized~ The G-fibers characteristically have a diameter of 9.53 + 0.63
microns and in the G-75 construction, have 2,000 filaments in a bundle,
which is constructed of 5 strands, each strand having 400 fil~ments.
- 28 -
Also a single bundle of around 3,000 or more filaments can be impregnated
and used as the flexible impregnated bundle of filaments of the present
invention.
A number of impregnated yarns produced with the coating
compositions of Table 1 were tested according to the tests in Table 2.
The breaking strength test for original samples, samples aged in humidity
for 14 days and samples sub~ected to 120F at 98 percent relative
humidity for 28 days and samples water aged at room temperature for 28
days and the flex resistance tests with the MIT flex folding test for
s~mples that were original, humidity aged at 28 days, and water aged at
28 days were performsd in accordance with standard test methods for
breaking strength and flex resistance. Unimpregnated yarns of sized
glass fIbers that were sized with the aqueous sizing composition of the
preferred embodiment were tested for original breaking strength and flex
properties, and the yarns gave values from 35.5 and 60 cycles
respectively. The specimens tested in Table 2 were conditioned at 78F
(26C) and 55 percent relative humidity for 24 hours before testing to
simulate some storage conditions. For the flex folding test of Table 2,
a 0.125 lb load was used with a 0.03 inch (.08 cm) mounting head with a
single strand being tested. As shown in Table 2, the coating
compositions impregnating the bundles of filament of the present
invention have improved flex properties.
- 29 -
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- 30 -
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-- 31 --
~2~
TABLE 2
EVALUATION OF EXPERIMEWTAL VINYL COATED YARNS
TENSILE A(;ING STUDY
YARN NO. LOI ORIGINAL HUMIDITY AGED; 120F & 98% RH WATER AGED, RT
14 DAYS 28 DAYS 28 DAYS
Ex 112 66.0 -- 66.2 66.0
Ex 212 56.9 46.5 47.5 51.0
Ex 312 56.0 47.6 48.i 53.3
Ex 512 51.9 47.9 41.3 46.4
Ex 612 63.1 58.5 59.1 63.6
Ex 712 68.0 64.5 62.8 67.3
Ex 912 -- -- -- --
Ex 10 12 -- -~
Ex 11 12 65.9 54.1 59.6 53.6
FATIGUE RESISTAN5E STUDY - MIT FLE~ FOLDING TEST
NUMBER OF CYCLES TO FAILURE
ORIGINAL HUMIDITY AGED;* 28 DAYS WATER AGED; 28 DAYS
Ex 1701 759 698
Ex 2NA 451 397
Ex 3351 307 282
Ex 5437 346 336
Ex 6792 675 741
Ex 71083 1017 932
Ex 9 948 -- __
Ex 10 1100 -- __
Ex il 501 752 811
*Aged at 120F and 98% Relative Humidity
-32 _
