Note: Descriptions are shown in the official language in which they were submitted.
~ 1735~0
METHOD OF PREPARING A PHENOLIC ALDEHXDE RESIN AND
RESIN COMPOSITION FOR AN ADHESIVE SYSTEM
TO BE APPLIED TO GLASS FIBERS
Background of the Invention
This invention is related to a method for preparing phenolic
aldehyde resin. More particularly, this invention relates to a method
for preparing resorcinol-formaldehyde resin for use in an adhesive
system for the adhesion of glass fiber tb rubber to produce reinforced
rubber goods.
Filamentary materials have been used extensively as reinforcing
material in rubber to produce reinforced rubber products, such as pneumatic
tires, power-drive belts, conveyor belts, high pressure hoses and the like.
The filamentary materials that are used to reinforce rubber material
include naturally occuring or synthetic filaments and may be in the form
of indiv~dual fibers, groups of fibers in the form of strand, rope, cord,
roving fabric and the like. The naturally occuring fibers include cotton,
silk, ramie and the synthetic fibers include rayon, nylon, polyester and
glass fibers.
Glass fibers are excellent filamentary material for reinforced
rubber and are superior to the natural and synthetic organic filamentary
materials, since the glass fibers do not become elongnted or deformed under
stress to the extent of the other filamentary materials~ Unlike other
filamentary materials, particular combinations of glass fibers with
encapsulating
,~
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X
1 1735~0
coating cooperate to yield reinforced rubber material-s that have greater
strength than even the glass or the coating material alone. While fila-
mentary materials, other than glass fibers, which are subject to substan-
tial stress elongation, are essentially limited in tensile strength to the
basic strength of their fibers, even if coated properly, coated glass
fibers have greater strength than the glass alone. For example, the low
modulus of elasticity of glass may be exploited to provide reinforced
rubber tires having superior road performance, if an appropriate coating
medium is provided to transfer stresses to all fibers in the glass fiber
cord so that loading throughout is substantially uniform. This pnenomenon
is illustrated by the observation that a typical uncoated fiber glass cord
(G75,5/0, filament count 2,000 i.e., 2,000 filaments of G fiber of about
9.14 micro meter diameter, 15,120 meters per kilogram, 5 strands per cord)
has a tensile strength of about 35 to 40 pounds (156 to 178 newtons) ASTM
test G178-52, but when coated with a coating, e.g., resorcinol formaldehyde
latex coating, such a cord has a tensile strength of about 50 to about 70
pounds (220 to 311 newtons).
The above-mentioned coated glass fiber cord, GT-75,5/0 has found
particular utility in the reinforcement of rubber for use in power trans-
mission belts and fiber glass reinforced tires and the like. In such a
coated glass fiber cord, a resorcinol formaldehyde latex coating is used
a~ the adhesive system to tran~fer the stresses and to provide adhesion
between the glass fibers and the rubber. Typically, the resorcinol for-
maldehyde, or resorcinol-phenol-aldehyde resin, useful in adhesive systems
for the adhesion of glass fibers to rubber is produced by a method using a
basic pH environment, i.e., around a pH of 8 to 10. The phenolic aldehyde
resin usually has an aldehyde level to phenolic compound level, usually
1 173580
resorcinol, of 0.4 to 0.8 to one phenolic compound on a mole basis. Such a
resin i9 characterized by a low degree of polymerization and minimum mol-
ecular weight. A particularly useful phenol aldehyde condensate, which
is a resorcinol formaldehyde resin, has a ratio of 0.6 formaldehyde to 1
resorcinol, and is sold under the designation Penacolite~ R-2200 resin.
There are several methods known in the art for preparing phenol
aldehyde polymers to be used in adhesive systems. As early as 1947 in U.S.
Patent No. 2,385,372 (Rhodes) a permanently fusible resin was prepared from
dihydroxybenzene tresorcinol) and an aldehyde in two stages so that a cata-
lyst was not present during the stages of a reaction. It was theorized
that having the catalyst present in the early stages of the reaction would
cause a resin to be too thick for the removal of the water produced by
the reaction. The problem was overcome by employing a two-stage reaction,
wherein the dihyAroxybenzene (resorcinol) is reacted at reflux conditions
with the aldehyde without a catalyst until a major portion of the reaction
is co~pleted. Then either an alkaline or acid catalyst is added and the
last increment of aldehyde reacts with the dihydroxybenzene.
Also a several stage reaction has been employed to produce a phe-
nolic aldehyde condensate in U.S. Patent No. 4,025,454 (Rouzier), wherein a
pre-condensate of formaldehyde, resorcinol and a para-substituted phenol
and a pre-condensate of resorcinol and formaldehyde are used. In a first
stage, resorcinol and a para-substituted phenol with two active methylene
groups are condensed in the presence of an acid catalyst. In the second
stage formaldehyde is condensed with the product of the first stage in an
alkaline medium. Then in the third stage the product of the second stage
is di~solved in water along with a resorcinol pre-condensate to form the
phenoplastic system, which is a mixture of phenol aldehyde condensates, then
combined with an elastomeric latex to form the adhesive for textile fibers.
1 173580
Also, in U.S. Patent No. 3,956,205 (Higginbottom) a resole i9
produced by a two-stage reaction. The first stage of the reaction is car-
ried out under novolac forming conditions, where an acid catalyst is used
to give a pK that is less than 5. In the first stage, one mole of phenol
is reacted with 0.05 to 0.30 moles of formaldehyde in order to favor the
formation of the dimer polymer and suppress the formation of higher oligo-
mers. In the second stage the reaction is conducted in the presence of a
basic catalyst, which has 8 pK greater than 9 with the addition of 1.75 to
3.5 moles of formaldehyde per mole of original phenol for the resole reac-
tion. At the end of the reaction, the catalyst i9 neutralized by addition
of acid to reduce the pH to between 6 and 8.5 to produce the resole resin.
The phenolic aldehyde resins of the prior art, such as Penacolite~
resorcinol formaldehyde resin, and those produced by the aforementioned
multi-stage processes can be improved upon for use in an adhesive system to
coat glass fibers that are used to reinforce rubber products. An i~prove-
ment of the phenolic aldehyde resin is desired to give the coated glass
fibers more flexibility and better resistance to compression fatigue
breakage, thereby yielding more durable and longer lasting reinforced
rubber products.
Qne of the many reinforced rubber products that would benefit
from the use of coated glass fibers having more flexibility and better
resistance to compression fatigue are pneumatic tires. A bias belted tire
having coated glass fibers that have more flexibility and better resistance
to compression fatigue would have improved wear characteristics and would
give extended mileage. Also radial tires having glass fiber belts, alone
or in combination with other filamentary material belts, containing coated
glass fibers having more flexibility and better resistance to compression
fatigue would give extended mileage and improved handling.
1173580
It is an object of the present invention to provide a method for
prepsring a thermoplastic, phenolic formaldehyde resin hav~ng
improved flexibility and having toughness and which is comprised of a sub-
stantial amount of the trimer polymer and to provide the said resin compo-
sition for use in an adhesive system used in coating glass fibers to render
the glass fibers more flexible and more resistant to compression fatigue
breakage.
Summary of the Invention
According to the present invention a thermoplastic, phenolic
aldehyde resin, which has a substantial amount of trimer polymer, and
which has a small amount of unreacted aldehyde is prepared. The method
involves a two-step reaction. In the first step a phenolic compound and
the aldehyde are reacted in smounts 90 that the ratio of aldehyde to phe-
nolic compound is in the range of about 0.8 to about 1.5 and to less than
100 percent completion in an acid medium at ambient conditions generally
for a period of time equivalent to about 3 hours to about 10 hours at a
temperature in the range of about 11C. (55F.) to about 32C. (90F.) to
produce a phenolic aldehyde resinous mixture. ~ the second step the
.. . . . .. . . .. . . ... . .
pH of the resinous mixture from the first stage is ad~usted within the range
of above 7 to about 7.5 to continue the condensation reaction of the phenolic
compound and aldehyde and reslnous mlxture to produce the more flexlble and
tough, thermoplastic, water soluble, phenolic aldehyde resin contalning
trimer a~d dimer polymers and having a small amount of unreacted aldehyde,
, ~' O~
but no/~L~e~ higher than trimer.
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The resinous mixture produced is a thermoplastic, wster soluble,
phenolic aldehyde resin that is idealy suited for use in an adhesive system,
like RFL systems, to coat glass fibers to give the coated glass fibers
better adhesion to rubber stock to produce reinforced rubber products.
Generally the phenolic compound and aldehyde undergoing reaction
and any acid or basic catalyst, if any, used to control the pH in tbe
respective steps of the proces~ of the invention can be any phenolic com-
pound, aldehyde, acid or basic catalyst known to those skilled in the art
of phenolic aldehyde resins. The term "resin" refers to synthetic resins
1~ that are organic substances synthesized from relatively simple chemical
compounds by c~ den~ tion polymerization reactions.
~ e~ ~c
The ~ aldehyde resin produced by the carefully controlled
two step process of the present invention gives phenolic aldehyde resins
that are flexible and tough and that when u8ed in an adhesive system for
coating glass fibers render the coated glas8 fibers more flexible and more
resistant to compression fatigue. Because of the pH control in both steps
of a two step process, and because the reactants added to the first step
are not completely reacted in the first step, and because of the relation
of the temperature and time conditions in both steps, the trimer polymer is
,
formed by the two step reaction. Other polymer forms such as t,he dimer
are also produced. The trimer polymer form can be represented by the
following formula:
OH DH OH
CH2 ~ FORMULA 1
- 6 -
~1735~0
where R is hydrogen or a hydroxyl group or mixture thereof, the trimer may
also have one or more pendant methyol groups from the phenolic rings in the
trimer. The pH control in the second stage allows for a slight degree of
cross-linking in the reaction product from the first stage reaction.
The phenolic aldehyde resin prepared according to the above
described process is actually a mixture of polymer forms with the trimer
polymer chain and where there is a small amount of cross-linking. This
phenolic aldehyde resin is an excellent resin for use in an adhesive
system for bonding glass fibers to rubber stock. The resin is first
combined with a conventional elastomeric latex so that the resin is
present in an amount of about 5 to about 50 parts by weight of the resin
per 100 parts by weight of elastomeric latex solids. Other components
such as wax, antioxidants and bond enhancers, one example of which is
resorcinol, and cross-linking retarding agents, for example concentrated
ammonia can be added to the adhesive system. Sufficient water is pres~nt
or added to ad~ust the total solids content of the adhesive system from
about 20 to about 40 percent solids. This adhesive system is used to
coat glass fiber materials such as individual glass fibers and groups of
glass fibers in the form of strand, rope, cord, roving, fabric and the
like.
Detailed Description
The phenolic aldehyde resin of the present invention has, as
mentioned above, trimer polymers in the mixture of polymers that con-
stitute the phenolic aldehyde resin, and is prepared by a carefully
controlled, multi-step process. In the first step the reactants are
reacted to less than 100 percent completion in an acid pH of around 3.5
to 5.5 and in the second step the resinous reaction is continued at a pH
in the range of about 7 to about 7.5.
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1 ~73580
It is believed, but the invention ig not limited by this belief,
that the process and the amounts of starting material result in
the composition in the following manner. The phenolic compound
has a strong ortho-para-directing influence because of the hydroxyl group,
and resorcinol, the predominant phenolic compound, is doubly activated in
the 2, 4 and 6 position on the ring. ~hen the aldehyde to phenolic com-
pound ratio is around one, a resin is obtained in an acid medium that is
permanently fusible and soluble. Very little, if any, cross-linking occurs,
and the resin consists predominantly of chains in which the phenol nuclei
are connected by means of methylene bridges to the activated positions of
the phenolic nuclei. In the acid medium the 2 and 6 positions of the
phenolic nuclei are favored for the condensation reaction. The rate of
reaction for the formation of the resin is directly proportional to the
hydrogen-ion concentration. By controlling the acidic pH in the first step
to be acidic, and by controlling the temperature and residence time within
the specified ranges, the resin reaction is less than 100 percent complete.
The result is that along with the resin produced in the first step there is
also present some unreacted aldehyde and possibly some unreacted phenolic
compound. Since thz resin formation reaction of the first step is less
than 100 percent complete, even though the ratio of aldehyde to phenolic
compound may be more than 1, even up to about 1.5, the resin produced is
still permanently fusbile and soluble. The mean molecular weight of the
resin from the first step of the reaction i9 generally less than 1,000.
.~
1~ ~35~
The reaction mixture from the first step has its pH ad~usted
to a range of above 7 to about 7.5. Although the rate of resin formation
in the presence of basic catalysts is independent of the hydroxyl ion
concentration above low concentrations of the catalyst, the small amount
of basic catalyst added to bring the pH to above 7 to 7.5 is low enough
so that the hydroxyl ion concentration has an effect on the rate of
reaction. The resinous material from the first step continues to react
with the unreacted aldehyde and any unreacted phenolic compound present
from the first step to form methylol groups which condense further upon
aging of the resinous material in the second step to produce a slightly
cross-linked but s~ill essentially linear, thermoplastic, phenolic resin
having trimer polymers in the mixture of polymers that compose the
phenolic aldehyde resin. The resinous mixture also contains dimer
polymer and no higher oligomer polymers such as tetramers and pentamers.
It is desirable to keep the amount of higher oligomers to a minimum,
since these higher oligomers are not water soluble. The resin mixture
with the substantial amount of trimer and dimer polymer has good
flexibility wh~ch is transferable to a substrate coated with the phenolic
aldehyde resin of the present invention.
Since abasicpH is used only in the second step, the formation
of the phenolic alcohols in the second step is mostly limited to methylol
rather than dialcohols or trialcohols, and this limiting effect assists in
the growth of the essentially linear, thermoplastic resin from the first
step. The limitation of the methylol phenolic alcohols along with the
directing influence of a baslc environment to reaction at the 2, 4 and
6 positions, leads to the growth of cross-links in the essentially linear
_ g _
1 1735~0
chains in the resinous mixture of the first step. The addition of the
methylol groups to provide 8 slight amount of cross-linking in the linear
chain of the resinous material from the first step gives the resinous
material a degree of toughness, while still maintaining the flexibility
of the linear chain. The reaction in the second step is continued for about
0.75 to about 10 hours to obtain the resin having good flexibility with
a small amount of cross-linking to give the resin a degree of toughness.
The cross-linking and/or branching is not to such an extent that the resin
becomes cross-linked and infusible.
In the process and composition of the present invention, the
structure of the phenolic compound is an important factor in the character- -
istics of flexibility and toughness of the resin and the resin coated sub-
strates. The rate of resinification depends on the nature and extent of
the substitution of the phenolic compound. With the phenolic compound
reacting with the aldehyde in the ortho- and para-positions to one or more
hydroxyl groups on the ring, there should be at least two open positions
either ortho or para to a hydroxyl group. The phenolic compounds useful
in the process and composition of the present invention include resorcinol
as well as resorcinol admixture with small amounts of ohenol, cresol and
mixtures of its isomers, xylenol or mixtures of its isomers, a mixture of
homologues of phenol and dihydric phenols, such as phloroglucinol, orcinol,
cresorcinol and m-~ylorcinol. It i8 preferred to use resorcinol as the
phenolic compound and in the alternative a mixture of resorcinol and phenol.
The aldehyde that is useful in the proces3 and composition of the
present invention iR one that acts as a methylené donor and i~ soluble in
the reaction medium. Aldehydes that can be used include: formaldehyde,
commonly used as 37 percent aqueous solution referred to as formalin, various
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1 ~73580
polymers of formaldehyde, such as paraformaldehyde, hexamethylene-tetramine,
acetaldehyde and furfural, and mixtures thereof. It is preferred to use
formaldehyde in the form of formalin.
Hereinafter in the specification, the phenolic compound will be
referred to as "resorcinol", the preferred phenolic compound, and the alde-
hyde will be referred to as "formaldehyde", the preferred aldehyde. But it
is to be understood that any of the aforementioned phenolic compounds or
aldehydes can be used, as described, in lieu of or in combination with the
resorcinol and formaldehyde.
The amounts of resorcinol and formaldehyde that are used are
those that give a mole ratio of formaldehyde to resorcinol in the range of
about 0.8 to about 1.5.
If too little an amount of resorcinol or too much formaldehyde
are used an infusible, cross-linked resin will be produced instead of a
fusible, thermoplastic resin with very little cross-linking that is
flexible and tough. If too much resorcinol and too little an amount
of formaldehyde are used the resin produced will not be as flexi-
ble as possible because the number of trimer polymers in the polymer mix-
ture will not be very large.
In the first step of the present invention the type of acid cata-
lyst that can be used include: sulfuric acid, oxalic acid, hydrochloric
acid, sulfamic acid, benzene sulfonic acid, toluene sulfonic acid or tri-
fluoracetic acid. The concentration of acid catalyst can be in the range
of around 0.001 to 0.002 ~ole equivalents per mole of resorcinol but the
acid pH of the first step reaction can be any acid pH with sufficient
1173580
amoune of catalyst added to achieve the desired pH. Preferably the pH of
the flrst step reaction is that acid p~ achieved by combining the resorcinol
and formaldehyde in the form of formalin for the reaction. Most preferably,
this pH that is achieved by combining the reactants produces autocatalysis
in the pH range of about 3.5 to 5.5. An acid pH above 5.5 which is achieved
by autocatalysis can be used by adding a small amount of basic catalyst.
If the pH is above about 5.5, then resorcinolic alcohols like methylol may
be produced and cross-linking may occur.
The reaction in the first step is conducted by adding the resor-
cinol and formaldehyde to a reaction vessel. Preferably, resorcinol and
formaldehyde, as formalin, are added to a reaction vessel in the proper
amounts to give the desired mole ratio. If a monohydric phenol, like
phenol, i5 present to any degree, the reaction conditions must be elevated
since monohydric phenols react more slowly than resorcinol or polyhydric
phenols. Generally, in the first step the resin reaction is conducted at
ambient conditions of temperature for the resin reaction between resorcinol
and formaldehyde in the range of about 55F. (13C.) to about 90F. (32C.)
when the residence time for the resin reaction in first step i9 in the
range of about 3 hours to about 10 hours, where the temperature and time
are inversely related. An equivalent residence time and temperature can
be used to give the same reaction rate as achieved by using the foregoing
condition~, i.e., as the temperature is increased, the residence time is
shortened. If the temperature is increased above 90F. (32C.) the resi-
dence time is shortened to less than 3 hours, and if the temperature is
decreased below 55F. (11C.) then the residence time must be increased
beyond 10 hours.
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1173580
At the end of the reaction in the first stép a resinous or poly-
meric mixture is produced.
The resinous mixture of the first step is subjected to a second
step by adjusting the pH of the resinous mixture to be in a range of above
7 to about 7.5. This adjustment is made by adding a basic catalyst to the
resinous mixture. Suitable basic catalysts include: sodium hydroxide,
potassium hydroxide, and other alkali metal hydroxides as well as alkali
metal carbonates, and alkaline earth hydroxides. These can be used as
solids but are preferably used in an aqueous solution. The concentration
of basic catalyst i6 generally around 3 percent per mole of resin and pref-
erably about .01 to about .06 mole of catalyst per mole of resin.
After the pH of the resinous mixture has been adjusted to the
proper pH, the resin reaction is continued so the unreacted formaldehyde
reacts with the resin and unreacted resorcinol. The reaction is conducted
at ambient conditions generally being a temperature in the range of about
55DF. (13DC.) to about 90F. (32C.) when the residence time is in the
range of about 0.75 hours to about 10 hours. If the temperature is increa~sed
or decreased above or below this range, the residence time is inversely
adjusted and therefore, any temperatures and residence times can be used
that allows for an equivalent reaction rate to that of the foregoing
conditions of temperature and time.
If the pH is above about 7.5 then too many methylol groups will
form and the resin may become cross-linked to too great an amount. If the
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1173580
pH is below about 7.0 then the acid type resin reaction of the first step
will continue to occur and the linear trimer polymer chain and
other ~olymer forms will not obtain the small about of cross-linking to
give a tough flexible re~in.
The above described two-step process may be conducted in a
batch-type reaction in one vessel or in a semi-continuous-type or con-
tinuous type reaction in one vessel with several stages or in several
vessels where the reactants and products are cascaded from one vessel
to the next. The reaction vessels used in the two-step process are any
reaction vessels known to those skilled in the art to be useful for resin
forming reactions. Preferably the reaction vessels or containers are
those that are used at ambient conditions, but that are jacketed to allow
for heating and cooling when ambient temperatures are too low during the
winter or too high during the summer in industrial production facilities.
The resorcinol formsldehyde condensate resin mixture of the
invention is combined directly with an aqueous elastomeric latex to form
an adhesive system for binding fiberous materials to rubber. The elasto-
meric latices useful in the adhesive system are the conventional latices
used in the formation of elastomer adhesive systems. Suitable elastomeric
latices are the synthetic rubber latices such as vinylpyridine-styrene-
butadiene terpolymer latices sold commercially under the trademark GEN-TAC,
GOODRITE, or PYRATEX. ~lso polybutadiene dispersions, styrene-butadiene
latices, reclaimed rubber dispersions, butyl rubber dispersions, and ethyl-
enepropylene-butadiene terpolymer rubber dispersions can be used. Also
other latices that can be used include natural rubber latex which may be
the crude rubber latex or rubber latex that contains added material or that
has been treated to alter the character of the rubber, for instance by
11735~0
degradation or by oxidation, or both. For instance, it msy contain any
desired accelerators, vulcanizers, stabilizers, dispersing agents or any
other substance, such as, those commonly used in the rubber industry. When
the rubber that is used is an artificial dispersion o~ any known synthetic
rubber it may likewise contain additional substances such as rubber accel- -
erators, vulcanizers, stabilizers, dispersing agents and the like. The
type or kind of rubber dispersion or elastomeric latex to be used depends
to some extent upon the type or kind of rubber stock to which it is desired
to bond the fiberous material, particularly tbe glass fibers. Besides the
specified elastomeric latices and dispersions any combination of the above
is hereby disclosed for the purposes of this invention.
Generally, the adhesive system can be made in any manner known
to those skilled in the art. The resin to elastomeric latex ratio of the
adhesive system should range between about 5 to about 50 parts by weight
of the resin per 100 parts by weight of elastomeric latex solids. The
resorcinol formaldehyde resin-elastomeric latex mixture may also contain
such additives as a wax to protect the elastomer in the coating composition
from attack by ultraviolet light; zinc oxide, magnesium oxide, litharge, or
red lead can be incorporated into the adbesive system to promote cross-linking
or curing of the elastomeric latex and improve resistance of the composi-
tion to aging, heat and light; anti-oxidants to protect the materials from
degradation due to oxygen; treated diatomaceous earths or chemical diatoma-
ceous earths and other ingredients known to those skilled in the art may be
added to the adhesive system to impart varying characteristics thereto.
Tbe aqueous adhesive system of the present invention should have
a pH of between above 7 to about 10. Any pH adjustment may be made by the
addition of an aqueous caustic solution, such as, sodium hydroxide or the
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~ ~73580
ammonium hydroxide to arrive at the desired pH. Also caustic solutionlike
sodium hydroxide or ammonium hydrox`ide can be added to tie up any unreacted
formaldehyde, if any, and thereby raise the pH of the adhesive system.
However, if the composition added thereto is a vinyl pyridine latex (PH
10.2), the dip may not require further pH ad~ustment. The adhesive system
thus prepared is ready for immediate use, or because of its stability may
be held for as long as a one week period before being used to coat fila-
mentary materials, particularly glass fibers. The adhesive system may be
applied to the surface of fiberous materials particularly glass fibers by
any conventional method such as dipping, spraying or spreading.
The filamentary material to which the adhesive system of the
present invention can be applied includes reinforcing materials, such as,
natural and synthetic organic fibers like cellulosic fibers, nylon fibers,
polyester fibers and glass fibers. Particularly, the filamentary material
are glass fibers. Generally in the method of forming glass fiber cord
in accordance with the present invention the glass fibers are formed at a
fiber-forming bushing, sized with an aqueous sizing composition, which is
a conventional glass fiber sizing composition, gathered into strand and
would on a formlng package. This process is more fully described in
U.S. Patents 3,437,517; 3,459,585; and 3,887,389. The forming packages
are then dried and mounted on a creel, unwound and coated with the
adhesive system coating composition of the present invention, and the
coated strands are dried.
Preferred Embodiment
In the preferred embodiment of the present invention, resorcinol
and formaldehyde in the form of formalin are reacted in the two step
reaction
- 16 -
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to less than 100 percent completion, first by starting with a mole ratio
for formaldehyde to resorcinol in the range of about 0.8 to about 1.5 and
second by controlling the reaction conditions.
The reaction conditions of the first step with the mixture of
formaldehyde and resorcinol at the preferred mole ratio include a pH in the
range of 3.5 to about 5.5. Therefore, in the first step of the preferred
embodiment an acid catalyst is not needed to obtain a pH in the range of
3.5 to 5.5 in the reaction between resorcinol and formaldehyde which is in
the form of formalin. In an alternative embodiment with different react-
ants, if the pH of the first step reaction is not in the range of less than
5.5 and greater than 3.5 from the presence of the reactants alone, then an
acid catalyst must be used. The reaction in the first step between resor-
cinol and formaldehyde is conducted at ambient conditions of temperature
preferably around 20C. to arount 32DC. for a period of time around 3 to
around 10 hours, preferably around 3 to around 4 hours.
The reaction conditions are adjusted in the
second step. The pH of this resin mixture is adjusted to be in the range
of above 7 to about 7.5 by adding about .01 to about .06 moles of an aque-
ous solution of potassium hydroxide per mole of resin, then the reaction of
the resorcinol formaldehyde resin, unreacted resorcinol and unreacted for-
maldehyde is continued in the second step at pH of above about 7 to about
7.5 at a temperature preferably in the range of around 20C. to around
32~C. and for a period of time in the range of around 2.5 hours to around
1173~80
10 hours, preferably around 5 hours. The resinoùs product issued from the
second step is a flexible but tough resorcinol formaldehyde condensate
resin mixture which is thermoplastic and being a mixture of polymer forms
with trimer polymer that contains a small amount of
cross-linking and that also contain~ less than 20 percent unreacted for-
maldehyde because of the incomplete reaction. The unreacted formaldehyde
is available for reaction with the resorcinol formaldehyde condensate mix-
ture when it is combined with an elastomeric latex to form an adhesive
system.
In the preferred embodiment, the preferred resorcinol formalde-
hyde resin produced by the aforementioned process is combined with a poly-
butadiene Latex such as LPM 6290 available from Goodyear, and a vinyl
pyridine styrene butadiene terpolymer latex available from Goodyear under
the trade designation "LVP 5622". The amounts of the two latexes used are
in the range of about 70 to about 90 parts per hundred parts rubber, most
preferably 70 parts of the 6290 and an amount in the range of about 10 to
about 30 parts per hundred parts rubber most preferably 30 parts of the
"5622" terpolymer. The ratio of resorcinol formaldehyde condensate resin
mixture to rubber latex should range between about 5 to about 50 parts
resin per 100 parts rubber latex solid, that i9, the amount of rubber on a
dry basis of the latex. The rubber includes those aforementioned rubbers,
such as, polybutadiene, SBR, vinyl pyridine and the like. ~ess than about
5 parts of resin will provide insufficient adhesion, whereas, greater than
about 50 parts of resin for lGO parts latex is economically undesirable.
Also to the resin latex adhesive system, there i6 added an antioxidant of
the phenolic type such as Bostex 294 available from Akron Dispersion of
Akron, Ohio. The amount of the antioxidant which is added, is usually in
* Trade mark
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~'
1 17358~
the range of around 1 part per 100 parts of dry rubbér to enhance the
coating flexibility over a wide range of temperatures. Also added is an
A aliphatic wax, such as, ~obilcer Q wax available from Mobile Company, which
is added in an amount in the range of around 5 parts per 100 parts of
rubber. Also another antioxidant like Paracure A09 antioxidant is added in
an amount of around 0.5 parts per 100 parts of rubber. After the adhesive
system coating composition is prepared, it is allowed to age at ambient
temperatures for at least around 10 hours. This ageing allows the unreacted
formaldehyde of the resorcinol formaldehyde condensate resin mixture to
react further with the condensate resin while it is in the presence of
the elastomeric latexes. This produces a long-chained, slightly cross-
linked, thermoplastic condensate resin that i3 associated with the latexes.
After the ageing period a small amount of a nitrogenous base such as ammonia
or low to medium boiling amine compounds, i.e., diethanolamine but prefera-
bly a small amount of concentrated ammonia (28~ solution) i9 added to tie
up any unreacted formaldehyde 90 that no further resin cross-linking occurs.
The amount added is usually less than 1 part per 100 parts rubber. The
ammonia addition 3tabilizes the adhesion system coating composition and
prolongs its shelf life.
In addition, it has also been found that the bonding character- -
istics of the adhesive system can be improved by adding around 1 part per
100 parts of rubber of resorcinol after the addition of the ammonia solu-
tion. The added resorcinol increases the adhesion level of the adhesive
system by increasing the resin content and increases the polarity of the
adhesive system coating composition for better wettability and impregnation.
In general, the method of producing glass fiber bundles coated
with the adhesive coating composition of the present invention is to contact
~ 7-~ A~ e~
-- 19 --
11735~3
a continuous bundle, for example, strand which has been previously sized,
with the coat~ng composition of the invention, and dry the coating within
the bundle, and then cure the coating residing within and about the bundle
to produce a coated cord suitable for rubber reinforcement. The contacting
can be performed by rollers or through a bath and dye apparatus. A
particularly advantageous method for producing the glass fiber bundles of
the invention based upon the method described in U.S. Patent No. 3,619,252
"Manufacture of Elastomeric Coated Glass Fibers" by Alfred M. Roscher.
This invention is particularly applicable to glass fiber, filament bundles,
having complete filament encapsulation and having a relatively high ratio
of coating weight, i.e., about 15-40 percent to glass weight.
Preferably the glass fiber strands are coated in the following
manner. A plurality of glass fiber strand, which have been previously
sized, are combined in parallel relation and passed between a guide in
tangential contact across motor driven rollers. The rollers are partially
immersed in the adhesive system coating composition of the present inven-
tion and these rollers pick up the coating composition when rotated. The
coating which is picked up is brought into contact with the glass fiber
strand, coating and impregnating the combined bundle of strand. Relaxation
of the tension in the combined bundle of strands opens the spacings between
the fibers and between the strands enhancing impregnation of the coating
into the bundle. Typically the coating composition solids of the aqueous
dip will be about 20-40 percent, depending upon the total amount of coating
composition solids to be imparted into the glass fiber cord. Lower solid
level will produce cord with low coating add-on based on the weight of the
glass and a higher solids content will produce a coated glass fiber cord
- 20 -
. . .
~c~
~ ~ 73580
having a high amount oE coating composition solids based on the weight of
the glass. Thus, coating add-on weight is about 15 to about 40 percent
based on the weight of the glass fibers, more preferably about 20 to about
30 percent to provide a coated glass fiber bundle or cord which is useful
for the reinforcement of elastomeric matrices.
After the contacting of the fiber glass bundle with the coating
composition of the present invention for a sufficient time to fully impreg-
nate the bundle with the water and solids containing dip, the bundle is
passed through a dielectric heater or drying oven. The drying oven is so
designed and operated that water is removed rapidly from the inside of the
bundle as well as from the surface of the bundle without substantial migra-
tion of the solids from the interior to the surface of the bundle and with-
out excessive blistering.
The dried glass bundle is then sub~ected to heat in order to
partially cure the rubber adhesive coating throughout the bundle. It is
preferred to partially cure the coating while completing the curing of the
coatlng of the glass fiber, when it is embedded in the rubb~r matrix being
reinforced during the curing of the rubber in the final article.
A second method for making the glass fiber bundles of the inven-
tion is based upon the method described in U.S. Patent No. 3,718,448
entitled "Fiber Forming and Coating Process" by Warren W. Drummond and
Donald W. Denniston which is assigned to the present assignee.
As to the rubber to which the coated fiber glass cord will
adhere, the invention contemplates any compound of natural rubber stock or
any compound of synthetic rubber stock, such as, polymerized isoprene, or
polymerized butadiene, or polymerized halogen substituted butadiene, such
X
11~3580
as, a halogen-2-butadiene-1,3-polymer, for example, chloro-2-butadiene-1,3-
polymer and other types.
The invention is further illustrated by the following Examples
wherein parts are parts by weight unless otherwise indicated. The Examples
should be construed to illustrate the invention and its preferred embodi- -
ment but not to limit the invention.
EXA~PLE I
The thermoplastic resorcinol formaldehyde resin of the present
invention is prepared by first adding about 70 to 75 percent of the total
water at about 22 to 25C. to a pre~ix tank. Resorcinol in an amount
of 57.6 pounds (26 kg.) is added to the water in the premix tank and agi-
tated until completely dissol~ed. Then 61.2 pounds (27.8 kg.) of formalde-
hyde is added to the premix tank containing the water snd resorcinol. The
resorcinol and formaldehyde are reacted in the aqueous solution at a tem-
perature of 78-80F. (25.6-26.7C.) at a pH of 5.0 plus or minus 0.5 for
a period of four hours. A solution of potassium hydroxide in water was
prepared by adding 1.8 pounds (0.82 kg.) of potassium hydroxide to 24
pounds (10.39 kg.) of water and mixing together until the potassium
hydroxide is dissolved. At the end of four hours the aqueous solution of
potassium hydroxide was slowly added to the premix tank containing the
reacted resorcinol and formaldehyde. After the addition the temperature
was maintained at 75-80F. (24-27C.) at a pH of 7.5 and the reaction was
continued for a period of time of 5 hours. The resorcinol formaldehyde
resin product contained after 5 hours i9 the thermoplastic, water soluble,
resin of the present invention, having trimer polymers that are slightly cross-
linked or uncross-linked tr~mer polymers and dimer polymers and no higher
V
1 173580
oligomers than trimer making up the polymer mixture that constitutes the
resin, and also having a s~all amount of unreacted formaldehyde.
EXAMPLE II
Eleven gallons (3.79 L) of deionized water at 110F. (43.3C.)
was added to a tank and 19.2 pounds (8.71 kg.) of resorcinol was added to
the water in the tank and a~gitated until comPletely dissolved. To this
aqueous mixture resorcinol there was added 20.4 pounds (9.25 kg.) of for-
maldehyde and the temperature was adjusted to 78-80F. (26-27C.) at a
pH of 5.0 plus or minus 0.5. This temperature was maintained for a period
of time of four hours. In the meantime an aqueous solution of potassium
hydroxide was prepared by mixing 0.6 pounds (0.27 kg.) potascium hydroxide
and 8 pound~ (3.63 kg.) of teionized water. At the end of four hours the
aqueous solution of potassium hydroxide was added slowly to the resorcinol
formaldehyde reaction mixture in the tank. After the addition of the aque- -
OU5 potassium hydroxide ~olution the temperature was maintained at 75-80F.
(24-27C.) at a pH of 7.5 for a period of time of 5 hours. After the 5
hours the resorcfnol formaldehyde resin product was the thermoplastic,
water soluble, resorcinol formaldehyde resin of the present invention.
EXAMPLE III
Twelve gallons of dioni~ed water at 110F. (43.3C.) was added to
a tank and 20.8 pounds t9.4 kg.) of resorcinol was added to the water in
the tank and agitated until completely dissolved. To this aqueous solution
of resorcinol there was added 22.8 pounds (10.3 kg.) of formaldehyde. The
formaldehyde and resorcinol aqueous solution was reacted at a temperature
- 23 -
11735~
of 78--80F. (26-27C.) at a pH of 5.0 plu9 or minus 0.5 for a period of
time of four hours. Meanwhile an aqueous solution of potassium hydroxide
was prepared by dissolving 0.6 pounds (0.27 kg.) of potassium hydroxide in
two gallons of deionized water. At the end of four hours the aqueous solu-
tion of potassium hydroxide was slowly added to the resorcinol formaldehyde
reaction mixture. After the addition of the aqueous potassium hydroxide the
temperature of the reaction mixture was maintained at 75-80DF. (24-27C.)
and the pH of the reaction was continued for a period of time of five hours
after which the resorcinol formaldehyde produce was the termoplastic, water
soluble, resorcinol formaldehyde resin of the present invention.
EXAMPL~ IV
Production of Adhesive System with Long-Chain, Thermoplastic, Water Soluble
Resorcinol Formaldehyde Resin
To a main mix tank there was 1,440 pounds (653 kg.) of polybu-
tadiene latex, Goodyear 6290 and 1,080 pounds (490 kg.) of vinylpyridene
and polybutadiene latex, Goodyear 5622. To this mixture of latices there
was added 133 gallons (503.5 L) of deionized water and while dolng that
21.6 pounds (9.8 kg.) of antioxidant, Boxtex 294 was added with deionized
water to the mix tank. To a separate mixing tank there was added 46 gal-
lons of deionized water and 10.8 pounds (4.9 kg.) of the antioxidant Para-
cure A-09. To this mixture there was added 108 pounds (4.9 kg.) of wax,
Mobilcer Q and the solution was mixed for ten minutes and then added to the
mixture of polybutadiene and vinylpyridine latices in the main mixing tank.
After the resorcinol formaldehyde resin produced according to ~xample I had
been aged for 9 hours it was added slowly to the mix tank containing the
mixture of polybutadiene and vinylpyridene latices and wax and antioxidant.
After the resorcinol formaldehyde resin was added, the mixture was aged for
- 24 ~
1 173580
10 hours. Care must be taken that the resorcinol formaldehyde resin has a
pH of 7.5 or above to avoid coagulation of the latices. If the pH of the
resin is not 7.5 or above it may be adjusted by the addition of potassium
hydroxide to the resin before it is added to the polybutadiene and vinyl-
pyridene latices. Then, a mixture of aqueous ammonium hydroxide is prepared
by dissolving 7.2 pounds (3.3 kg.) of ammonium hydroxide in 9 gallons (34
L) of deionized water and after the resin latex mixture has been aged the
aqueous ammonium hydroxide is added to the resin latex mixture in the main
tank. The mixture is then agitated for a period of time to produce the
adhesive system coating composition having a percent solid of 27 plus or
minus 0.5, a pH of a 8.5 plus or minus 0.3, and a dip life of 50 hours.
This adhesive system coating composition can be used to bind glass fibers
to rubber matrices.
EXAMPLE V
Preparation of Adhesive System Coating Composition Using Long-Chain,
Thermoplastic, Water Soluble Resorcinol Formaldehyde Resin
To a mixing tank there was added 532 pounds (14.5 kg.) of poly-
butadiene latex, Goodyear 2374, and 400 pounds (181.4 kg.) of a styrene-
butadiene-vinylpyridine latex, Goodyear 5622. In addition there was added
48 gallons (132 L) deionized water along with 8 pounds (3.6 kg.) of anti-
oxidant, Bostex 294. In a separate tank 10 gallons (37.9 L) of deionized
water was added along with 4 pounds (1.8 kg.) of antioxidant Paracure A-09
and 40 pounds (18 kg.) of a wax Mobilcer Q which was mixed for 10 minutes
and then added to the main mixing tank containing the mixture of latices.
After the long-chain, thermoplastic, water soluble resorcinol formaldehyde
produced in Example III hac been aged for 9 hours, it was slowly added to
the main mixing tank that contained a mixture of latices and antioxidant
and wax. After the resorcinol formaldehyde resin was added the mixture was
- 25 -
1 173530
~ o~, ~
aged for 10 hours. An aqueous solution of a~b~ff~hff~ hydroxide was prepared
by adding 2.4 pounds tO.18 kg.) of ammonium hydroxide to 4 gallons (15 L)
of deionized water. Thi~ aqueous ammonium hydroxide solution was added
very slowly to the resin latex mixture and was stirred for about 10 minutes.
An aqueous resorcinol solution was then prepared by adding four pounds (1.8
kg.) of resorcinol to 4 gallons (15 L) of deionized water which was mixed
together until the resorcinol was completely dissolved. The aqueous resor-
cinol solution was then added very slowly within about 15 minutes to the
main mix tank containing a resin latex mixture. The mixture was then
stirred for 25 mintues and then automatically agitated for one minute every
half hour to produce an adhesive system coating composition having a per-
cent solid~ of 27 plus or minus 0.5, a pH of 8.5 plu9 or minus 0.3, and
a dip life of 50 hours. The resorcinol solution was added to the resin
latex composition to improve the bonding characteristics of the adhesive
system. The added resorcinol increases the adhesion level of the adhesion
system by increasing the resin content and increase the plurality of the
dip for better wettability and impregnation.
EXAMPLE VI
The Preparation of a Long-Chain, Theremoplastic, Water Soluble Resorcinol
Formaldehyde Resin and Adhesive System.
To a pre-mixed tank there was added 24 gallon~ (91 L) of deion-
ized water at 110F. (43.4C.). To the water in the reaction vessel, there
was added 96 pounds (43.5 kg.) of resorcinol which was agitated until com-
pletely dissolved. To the aqueous solution of resorcinol there was added
56.8 pounds (25.8 kg.) of formaldehyde. The resorcinol and formaldehyde
were reacted in the aqueous solution at a temperature of 78-80F. (26-
27C.) at a pH of 5.0 plus or minus 0.5 for a period of time of 4 hours.
- 26 -
11~3580
An aqueous potassium hydroxide solution was prepared by dissolving 1.6
pounds (0.73 kg.) of potassium hydrxide in 40 pounds (18 kg.) of deionized
water. At the end of the fours hours reaction time of the resorcinol and
formaldehyde under acidic conditions the aqueous solution of potassium
hydroxide was added slowly to the reaction mixture, After the addition the
pH was around 7.5 and the reaction was continued at a temperature of 78-
80F. (26-27C.) for a period of 5 hours. At the end of this time the
resorcinol formaldehyde resin produced was the thermoplastic,
water soluble resorcinol formaldehyde resin of the present inven~ion.
In a main mix tank there was added 912 pounds (414 kg.) of a
styrene-butadiene-latex Firestone SR6642, and 400 pounds (181.4 kg.) of a
carboxy polybutadiene latex GenFlow 8020 and 720 pounds of a polybutaidene
styrene latex, Firestone S-272. To this main mix tank there was also added
140 gallons (530 L) of deionized water along with 16 pounds (7.26 kg.) of
antioxidant, Bostex 294. Then in a separate mix tank the~e was added 20
gallons (75.7 L) of deionized water and 8 pounds of an antioxidant Paracure
A-09 along with 80 pounds (36.3 kg.) of wax, Mobilcer Q, which was mixed
for 10 minutes, and then added to the main mix tank containing the mixture
of latices. After the long-chain, theremoplastic, water soluble, resorci-
2n nol formaldehyde resin produced above has aged for 9 hours it was slowly
added to the main mixing tank containing the mixture of latices. After the
resin was added the mixture was aged for 6 hours and 280 pounds (127 kg.)
of Neoprene latex, Neoprene 735-A was added slowly to the mixture. An
aqueous solution of ammonium hydroxide was prepared by dissolving 4.8 (2.2
kg.) pounds of ammonium hydroxide and 6 gallons (23 L) of deionized water.
This aqueous solution of ammonium hydroxide was added to the resin latex
mixture after the mixture had aged for about 30 minutes after the addition
- 27 -
~ . i,
1173580
of Neoprene. The addition was accomplished very slowly and after the addi-
tion t:he mixture was aged for 15 minutes, and after 1 hour was placed on an
agitat:or for automatic agitation of one minute each half hour to produce an
adhesive systems coating composition having a solids content of 28.0 plus
or minus 0.5, a p~ of 8.5 plus or minus 0.3, a dip life of 60 hours.
EXAMPLE VII
Coating Glass Fibers With Adhesive Systems Coating Composition Containing
Long-Chain, Thermoplastic, Water Soluble, Resorcinol Formaldehyde Resin.
Gla~s fibers that were formed at a fiber-forming bushing, sized
with an aqueous sizing composition gathered into strand and wou~d onto a
forming package that is then dryed and mounted on a creed are unwound and
coated with the adhesive system coating composition of the present inven-
tion. Fiber glass strands such as G-75,5/0 or G-75/10/0 or G-75,15/0,
which characteristically are 9.6 x 10-6 meters to 9.1 x 10-6 meters in
diameter and have a filament count of 2,000 in a cord being conséructed
of 5 strands each strand having 400 filaments, are coated by the adhesive
system coating composition of the present invention. Also, K fibers, such
as, K-15 strand typically having 1,00 filaments therein each filament hav-
ing a diameter of about 13.34 plus or minus 0.63 microns (5.25 plus or
minus 0.25 x 10-4 inches) wherein 1 to 3 strands per cord are used, can
also be coated by the adhesive system coating composition of the present
invention. When G cord is to be used in bias belted tires the cord should
be constructed to 5 strands and when the cord is to be used in radial
tires, there should be 10 to 15 strands per cord.
The 10 to 15 strand cord allows higher packing of the cord per
unit area, thereby providing greater strength to the tire carcass. This
strength is necessary to obtain the desirable properties in radial ply
- 28 -
1 ~73580
tires, G fibers were sized with a chemical size containing predominantly
polypropylene emulsion containing 25 percent by weight of polypropylene
and 6 percent by weight of emulsifying agent and also containing smaller
amounts of polyvinyl alcohol, and amide imidazolene, and methylacryloxy-
propyltrimethoxysilane. This sizing composition was applied to the fibers
during formation and the strand formed therefrom was dried and/or cured in
accordance with the method described in U.S. Patent No. 3,655,353.
Adhesive system coating composition prepared in Example IV and
Example V were used to coat the glass fiber cord. The glass fiber cord was
prepared by coating 15 of the sized strands with the coating composition
from Example IV and Example V. This cord was incorporated into a rubber
stock and also used to reinforce the belts of-pneumatic tires.
The tire cord properties of these coated fiber glass cords were
tested for the adhesion level of the adhesive system in various rubber
stocks. The results of these tests are presented below. The successful
bonding of rubber to tire cord is measured by several tests one of these is
strip adhesion. Strip adhesion for rubber coated glass cord is determined
by the following method. A cylindrical drum is wrapped by a 10.2 x 26.7
centimeter x 0.1 centimeters strip of rubber stock. The rubber stock occu-
pied substantially all of the surface area of the cylindrical drum. The
coated glass fiber year is wrapped about the rubber stock on the drum in a
cylindrical fashion, providing a continuous layer of yarn over the rubber
stock. The wound rubber stock has been moved from the cylinder and cut
into a 7.6 x 25.4 centimeter sample. A strip of the 7.6 x 25.4 centimeter
rubber is placed fn a 7.6 x 25.4 centimeter mold and the above rubber strip
with the coated strand thereon is placed in the mold with the strand side
- 29 -
1 173580
away from the first rubber strip. A number of 27.62 x 2.54 centimeter
strips of Holland cloth are placed at opposite ends of the strand side of
the rubber ~tr~p. Another 7.62 x 25.4 centimeter rubber strip is placed
~ /o //C'~
over the N~*~ cloth and lastly, a 7.62 x 25.4 centimeter rubber strip of
coated strand thereon is placed on the last mentioned rubber strip with the
strand side in contact with the last mentioned rubber strip. The mold is
closed and the rubber cord laminate is cured at 4,780 pascals for 30 min-
utes at 149C. The rubber cold laminate is re~oved from the mold and is
allowed to simply cool overnight.
The laminate is cut into 14 x 2.54 centimeter strips and heated
for 30 minutes at 121C after which the Holland cloth is removed from the
laminate. After setting an Instron~ test device for a gague length of
1.27 to 1.9 centimeter and calibracting the unit for a cross head speed of
5.1 centimeter per minute, the bottom layer of the heated rubber and the
exposed cord are placed in the top jaw, and the top layer of the heated
rubber is placed in the bottom jaw of the test device. me Instron~ test
device is operated until a separation of 5.1 centimeter is obtained and the
loading is noted. m e top layer is inserted into the top jaw and the cord
in the bottom jaw with a gauge length of 1.27 to 1.9 centimeters. The
Instron~ device is operated until a separation of 5.1 ic obtained and the
loading is noted. m e test is repeated for the opposite end of the speci~
men and for additional specimens included in the example. The results of
the test are averaged for adhesion of the cord to rubber.
The "In-rubber tensile" is determined by curing the cord in a
rubber matrix and testing the glass fiber cord reinforced matrix in an
Instron device with a gauge of 17.8 - 19 centimeter and a cross head speed
of 5.1 centimeter per minute. The jaws are separated and the force required
to break the sample is recorded.
- 30 -
1173~80
The results of the foregoing described test procedures are pre-
sented in Table I.
TA8LE I
Cord Strip Adhesion in Various In-Rubber-Tensile
Rubber Stocks lb.
Stock Al Stock B2 Stock C3
lb/Ratin~* lb/Rating lb/Rating
Coating 21/1.3 47/4.5 34/4.8 200
Composition of
Example IV
Coated with 41/4.7 45/5.0 44/5.0 210
Composition of
Example V
Coated with 36/4.8 49/5.0 47/5.0 229
Composition
Similar to
Example V
wherein the
Goodyear Latices
are replaced by
Firestone Latices
(SR 6642 and SR 272)
*Rating: 1 - 5 : 1 is adhesive failure, and 5 is cohesive failure
1. Rubber Stock available from McCreary Tire & Rubber Co.
2. Rubber Stock available from B. F. Goodrich Co.
3. Rubber Stock available from Firestone Tire & Rubber Co.
Tests were also performed on the fiber glass cord coated with the
adhesive systems coating composition of the present invention, when the
cord was bound to rubber and u~ed in pneumatic tires. One such test is
the Gristmill test which measures the compression fatigue resistance of
the cord. A major part of the stre~s is applied to the outside shoulder of
the tire where cord breakage is most liXely to occur. Cord breaks in each
tire belt are totaled and for uniformity, adjusted to breaks/meter of belt
length.
- 31 -
~173~
The ambient gristmill test involves the fol-lowing:
a. inflate tires to 24 psi at 75F,
b. mount one tire on the right front position of a standard
vehicle which has been pre-loaded to 100 percent T and RA load at 24 psi.
Record tire pressure at this point and do not make any adjustments,
c. Drive the vehicle at 15 miles per hour for 800 laps in
counter-clockwise direction. Record temperature and pressure of tire at
the end of the test.
d. x-ray the tested tire inflated to determine a condition of
the cord.
The cold gristmill test involves:
a. inflate tires at 24 p9i (1.69 kg/km2) at 70F (21C),
b. tires are cooled for 4 hours to -40F (-40C) then one tire
is removed from the cold box and placed on the right front position of the
car. It is allowed to warm up to -25F (-32C) before starting the test.
Record tire pressure at this point and do not make any adjustment,
c. drive the car at 15 mph (8.05 km/rh) for ten laps in counter-
clockwise direction. Thi8 constitutes one cold cycle. Record temperature
and pressure of the tire at this point. Put tire back in the cold box for
4 hours at -40C.
d. Put the tire back in the cold box for four hours at -40C.
e. Repeat steps b, c, and d for the specified number of cycles.
f. x-ray the tested tire inflated to detemine the cord breakage
if any. The test conditions for both ambient and cold include an 85 foot
(24.4 meters) diameter circle wherein 100 laps at 15 miles per hour in a
clockwise direction are made at 100 laps at 15 miles per hour in (8.05 km/
hr) (counter-clockwise direction are made. The tires are inflated 24 psi
- 32 -
1 1735~
(1.6~ kg/cm2). The load is a T~RA rated load for 24 psi (1.69 kg/cm2)
and the fixed position mounting is the front mounting.
Table II presents the results of Gristmill Testing on the glass
fiber yarm embedded in rubber stock with the use of the adhesive system of
Examples IV, V, and VI, and a commercial glsss radial tire cord.
TABLE II
Radial Tire Cord Performance
Gristmill Test
Ambient Gristmill Test Cold Gristmill Test
Cord Coated With:1600 laps:Breaks/Meter* 7 cycles:Breaks/Meter
Rxample IV 3 0
Adhesive System
Example V 5 3
Adhesive System
Example VI 15 100
Adhesive System
Commercial 10 4
Cord
*B/M is the average number of breaks per one meter of tire belt.
In Table III Indoor Cold Wheel Test: 5 51ip angle involves
cooling the tire to a -20F (-290C) mounting tire on a loaded ~heel and
running for one hour. This is one cycle. This step is then repeated to a
total of 4 cycles. The tire is stripped and the belts are rated. A rating
of 7 is no cord failure and a ratin8 of 1 is excessive cord breakage.
TABLE III
Radial Tire Cord Performance
Indoor Cold Wheel Test : 5 Slip Angle
Belt Rating*
Cord Coated With: No. of Cycles Top Belt Bottom Belt
Example IV 4 4.5 6.8
Adhesive System
Example V 4 5.5 6.9
Adhesive System
Commercial Cord 4 5.5 6.5
1173580
*Belt Rating: l to 7:1 is sever cord breakage and 7 is zero cord breakage.
The foregoing has described the composition of a thermoplastic,
water soluble phenolic aldehyde resin particularly a resorcinol resin which
has improved flexibility along with toughness and the process for producing
same. The foregoing has also described the use of the improved flexible
tough phenolic aldehyde resin in an adhesive system coating composition,
wherein the resin is combined with a latex or latices along with other
conventional additives to produce a dip for fibrous material particularly
glass fiber strand. The foregoing has also described the filamentary cord
like glass fiber cord produced with the use of the improved flexible and
tough phenolic aldehyde resin present in an adhesive system coating compo-
sition and the benefit of improved flexibility and improved resistance to
compression fatigue of the glass fiber cord coated with the adhesive
systems coating composition containing the improved flexible and tough
phenolic resin.
- 34 -
