Patent Application
20140027030
The invention relates generally to adhesive bonding for a pneumatic tire and, more specifically, to adhesive bonding of a pumping assembly to a pneumatic tire.
Normal air diffusion reduces tire pressure over time. The natural state of tires is under inflated. Accordingly, drivers must repeatedly act to maintain tire pressures or they will see reduced fuel economy, tire life and reduced vehicle braking and handling performance. Tire Pressure Monitoring Systems have been proposed to warn drivers when tire pressure is significantly low. Such systems, however, remain dependant upon the driver taking remedial action when warned to re-inflate a tire to recommended pressure. It is a desirable, therefore, to incorporate an air maintenance feature within a tire that will maintain air pressure within the tire in order to compensate for any reduction in tire pressure over time without the need for driver intervention.
In one form of the present invention, a pneumatic tire assembly comprises a tire having a pneumatic cavity, first and second sidewalls extending respectively from first and second tire bead regions to a tire tread region with the first sidewall having at least one bending region operatively bending when radially within a rolling tire footprint, a rigid structure for facilitating operation of the tire assembly with the rigid structure being bonded to the tire by a compound cement of high stiffness such that a stiffness gradient is created between the structure and the tire, and a sidewall groove defined by groove walls positioned within the bending region of the first tire sidewall. The sidewall groove deforms segment by segment between a non-deformed state and a deformed, constricted state in response to bending of the bending region of the first sidewall while radially within the rolling tire footprint. An air passageway is defined by the sidewall groove and deforms segment by segment between an expanded condition and an at least partially collapsed condition in response to respective segment by segment deformation of the sidewall groove when radially within the rolling tire footprint.
According to another aspect of the pneumatic tire assembly, the rigid structure is constructed of polyamide.
According to still another aspect of the pneumatic tire assembly, the rigid structure and the tire define a built-in tube-like cavity.
According to yet another aspect of the pneumatic tire assembly, the rigid structure and the tire reroute pressurized air to a pump assembly, and from there, into the pneumatic cavity.
According to still another aspect of the pneumatic tire assembly, a subcoat is applied to a bare surface of the rigid structure.
According to yet another aspect of the pneumatic tire assembly, a topcoat applied to the subcoat.
According to still another aspect of the pneumatic tire assembly, the compound cement is applied to the topcoat.
According to yet another aspect of the pneumatic tire assembly, the subcoat is dried to the bare surface of the rigid structure at 180 C for 8 min.
According to still another aspect of the pneumatic tire assembly, the topcoat is dried to the subcoat of the rigid structure at 180 C for 8 min.
According to yet another aspect of the pneumatic tire assembly, the compound cement is prepared from a homogenous slurry in a solvent over the topcoat.
In another form of the present invention, a tire assembly comprises a tire having a pneumatic cavity, first and second sidewalls extending respectively from first and second tire bead regions to a tire tread region with the first sidewall having at least one bending region operatively bending when radially within a rolling tire footprint, a rigid structure for facilitating operation of the tire assembly with the rigid structure being bonded to the tire by a compound cement of high stiffness such that a stiffness gradient is created between the structure and the tire, and a sidewall groove defined by groove sidewalls positioned within the bending region of the first tire sidewall. The sidewall groove deforms segment by segment between a non-deformed state and a deformed, constricted state in response to the bending of the first sidewall bending region being radially within the rolling tire footprint. An air passageway is defined by the sidewall groove. The air passageway resiliently deforms segment by segment between an expanded condition and an at least partially collapsed condition in response to respective segment by segment deformation of the sidewall groove when radially within the rolling tire footprint.
According to another aspect of the tire assembly, a separate tube disposed within the sidewall groove, the separate tube defining a circular air passageway.
According to still another aspect of the tire assembly, the separate tube has an outer profile corresponding to an inner profile of the sidewall groove.
According to yet another aspect of the tire assembly, the rigid structure comprises a plurality of check valves disposed at multiple arcuate positions about the sidewall groove.
According to still another aspect of the tire assembly, the compound cement secures the separate tube within the sidewall groove, the compound cement further securing the plurality of check valves to the separate tube.
According to yet another aspect of the tire assembly, the rigid structure is constructed of polyamide.
According to still another aspect of the tire assembly, the rigid structure and the tire define a built-in tube-like cavity; and the rigid structure and the tire reroute pressurized air to a pump assembly, and from there, into the pneumatic cavity.
According to yet another aspect of the tire assembly, a subcoat is applied to a bare surface of the rigid structure; and a topcoat is applied to the subcoat.
According to still another aspect of the tire assembly, the compound cement is applied to the topcoat.
According to yet another aspect of the tire assembly, the subcoat is dried to the bare surface of the rigid structure at 180 C for 8 min.
“Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100 percent for expression as a percentage.
“Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire.
“Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire.
“Chafer” is a narrow strip of material placed around the outside of a tire bead to protect the cord plies from wearing and cutting against the rim and distribute the flexing above the rim.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.
“Equatorial Centerplane (CP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of the tread.
“Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure.
“Groove” means an elongated void area in a tire dimensioned and configured in section for receipt of a an air tube therein.
“Inboard side” means the side of the tire nearest the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle.
“Lateral” means an axial direction.
“Lateral edges” means a line tangent to the axially outermost tread contact patch or footprint as measured under normal load and tire inflation, the lines being parallel to the equatorial centerplane.
“Net contact area” means the total area of ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the gross area of the entire tread between the lateral edges.
“Non-directional tread” means a tread that has no preferred direction of forward travel and is not required to be positioned on a vehicle in a specific wheel position or positions to ensure that the tread pattern is aligned with the preferred direction of travel. Conversely, a directional tread pattern has a preferred direction of travel requiring specific wheel positioning.
“Outboard side” means the side of the tire farthest away from the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle.
“Peristaltic” means operating by means of wave-like contractions that propel contained matter, such as air, along tubular pathways.
“Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire.
“Rib” means a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential groove and either a second such groove or a lateral edge, the strip being laterally undivided by full-depth grooves.
“Sipe” means small slots molded into the tread elements of the tire that subdivide the tread surface and improve traction, sipes are generally narrow in width and close in the tires footprint as opposed to grooves that remain open in the tire's footprint.
“Tread element” or “traction element” means a rib or a block element defined by a shape with adjacent grooves.
“Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread.
The invention will be described by way of example and with reference to the accompanying drawings in which:
Referring to
As seen from
As referenced in
The tube 42 may be profiled and geometrically configured for insertion into a groove 56. The groove 56 may have an elongate, generally elliptical configuration with a length L1 within a range of 3.65 mm to 3.80 mm complementary to the elliptical shape of the tube 42. The groove 56 may include a restricted narrower entryway 58 having a nominal cross-sectional width D3 within a range of 0.8 mm to 1.0 mm. A pair of groove-rib receiving axial detent channels 60, 62 of semi-circular configuration may be formed within opposite sides of the groove 56 for corresponding receipt of the tube locking ribs 52, 54, respectively. The channels 60, 62 may be spaced approximately a distance L3 within a range of 1.8 mm to 2.0 mm of the groove entryway 58. Detent channels 60, 62 may each have a radius of curvature R2 within a range of 0.2 mm to 0.5 mm. An inward detent groove portion 64 may be formed with a radius of curvature R1 within a range of 1.1 mm to 1.9 mm and a cross-sectional nominal width D1 within a range of 2.2 mm to 3.8 mm.
As best seen from
With reference to
The inlet device 68, as seen in
As shown in
Referring to
As the tire 12 continues to rotate in the direction 110 along the ground surface 118, the tube 42 may be sequentially flattened or squeezed opposite the tire footprint, segment by segment, in a direction opposite to the direction 110. A sequential flattening of the tube passageway 43, segment by segment, may cause evacuated air from the flattened segments to be pumped in the direction 116 within tube passageway 43 toward the outlet device 70. Air may flow through the outlet device 70 and to the tire cavity 40, as shown at 130. At 130, air exiting the outlet device 70 may be routed to the tire cavity 40 and serve to re-inflate the tire 12 to a desired pressure level. A valve system to regulate the flow of air to the cavity 40, when the air pressure within the cavity falls to a prescribed level, is shown and described in pending U.S. patent application Ser. No. 12/775,552, filed May 7, 2010, and incorporated herein by reference.
With the tire 12 rotating in direction 110, flattened tube segments may be sequentially refilled by air flowing into the inlet device 68 in the direction 114, as shown by
The above-described cycle may repeat for each tire revolution, with half of each rotation resulting in pumped air moving to the tire cavity 40 and half of each rotation resulting in pumped air moving back out the filter sleeve 92 of the inlet device 68 for self-cleaning the filter. It may be appreciated that while the direction of rotation 110 of the tire 12 is as shown in
The air tube/pump assembly 14 may be as shown in
The configuration and operation of the grooved sidewalls, and in particular the variable pressure pump compression of the tube 42 by operation of ridges or compression ribs 66 within the groove 56 is shown in
The uniformly dimensioned pump tube 42 may be positioned within the groove 56 as explained above—a procedure initiated by mechanically spreading the entryway D3 of the groove 56 apart. The tube 42 may then be inserted into the enlarged opening of the groove 56. The opening of the groove 56 may thereafter be released to return to close into the original spacing D3 and thereby capture the tube 42 inside the groove. The longitudinal locking ribs 52, 54 may thus be captured/locked into the longitudinal grooves 60, 62. The locking ribs 52, 54 resultingly operate to lock the tube 42 inside the groove 56 and prevent ejection of the tube from the groove 56 during tire operation/rotation.
Alternatively, the tube 42 may be press inserted into the groove 56. The tube 42, being of uniform width dimensions and geometry, may be manufactured in large quantities. Moreover, a uniform dimensioned pump tube 42 may reduce overall assembly time, material cost, and non-uniformity of tube inventory. From a reliability perspective, this results in less chance for scrap.
The circumferential ridges D0 through D6 projecting into the groove 56 may increase in frequency (number of ridges per axial groove unit of length) toward the inlet passage of the tube 42, represented by the outlet device 70. Each of the ridges D0 through D6 may have a common radius dimension R4 within a range of 0.15 mm to 0.30 mm. The spacing between ridges D0 and D1 may be largest, the spacing between D1 and D2 the next largest, and so on until the spacing between ridges D5 and D6 is nominally eliminated. While seven ridges are shown, more or fewer ridges may be deployed at various frequency along the groove 56.
The projection of the ridges into the groove 56 by radius R4 may serve a twofold purpose. First, the ridges D0 through D6 may engage the tube 42 and prevent the tube from migrating, or “walking”, along the groove 56 during tire operation/rotation from the intended location of the tube. Secondly, the ridges D0 through D6 may compress the segment of the tube 42 opposite each ridge to a greater extent as the tire 12 rotates through its rotary pumping cycle, as explained above. The flexing of the sidewall may manifest a compression force through each ridge D0 through D6 and may constrict the tube segment opposite such ridge to a greater extent than otherwise would occur in tube segments opposite non-ridged portions of the groove 56. As seen in
The number of ridges D0 through D6 and respective radii of each ridge may be constructed outside the above ranges to suit other dimensions or applications. The increasing radius of curvature in the direction of air flow may result in the ridges D0 through D6 projecting at an increasing amplitude and, to an increasing extent, into the passageway 43 toward the outlet device 70. As such, the passageway 43 may constrict to a narrower region 138 toward the outlet device 70 and cause a correspondingly greater increase in air pressure from a reduction in air volume. The benefit of such a configuration is that the tube 42 may be constructed smaller than otherwise necessary in order to achieve a desired air flow pressure along the passageway 43 and into the tire cavity 40 from the outlet device 70. A smaller sized tube 42 may be economically and functionally desirable in allowing a smaller groove 56 within the tire 12 to be used, thereby resulting a minimal structural discontinuity in the tire sidewall.
D1=2.2 to 3.8 mm;
D2=0.5 to 0.9 mm;
D3=0.8 to 1.0 mm;
R4=0.15 to 0.30 mm;
L1=3.65 to 3.8 mm;
L2=2.2 to 2.3 mm;
L3=1.8 to 2.0 mm.
The above ranges may be modified to suit a particular dimensional preference, tire geometry, or tire application. The external configuration of the tube 42 may include beveled surfaces 138, 140 adjoining the end surface 48; parallel and opposite straight intermediate surfaces 142, 144 adjoining the beveled surfaces, respectively; and a radiused nose, or forward surface 146, adjoining the intermediate surfaces 142, 144. As seen from
D1=2.2 to 3.8 mm;
D2=0.5 to 0.9 mm;
D3=0.8 to 1.0 mm;
R4=0.15 to 0.30 mm;
L1=3.65 to 3.8 mm;
L2=2.2 to 2.3 mm;
L3=1.8 to 2.0 mm.
The above ranges may be modified to suit a particular dimensional preference, tire geometry, or tire application.
D1=2.2 to 3.8 mm;
D2=0.5 to 0.9 mm;
D3=2.5 to 4.1 mm;
L1=3.65 to 3.8 mm;
L2=2.2 to 2.3 mm;
L3=1.8 to 2.0 mm.
The above ranges may be modified to suit a particular dimensional preference, tire geometry, or tire application if desired.
From the forgoing, it will be appreciated that the present invention may comprise a bi-directionally peristaltic pump assembly 14 for air maintenance of a tire 12. The circular air tube 42 may flatten, segment by segment, and close in the tire footprint 100. The air inlet device 68 may include an outer filter sleeve 92 formed of porous cellular material and thereby render the air inlet device 68 self-cleaning. The outlet device 70 may employ a valve unit (see co-pending U.S. patent application Ser. No. 12/775,552, filed May 7, 2010, incorporated herein by reference). The peristaltic pump assembly 14 may pump air through rotation of the tire 12 in either direction, one half of a revolution pumping air to the tire cavity 40 and the other half of a revolution pumping air back out of the inlet device 68. The peristaltic pump assembly 14 may be used with a secondary tire pressure monitoring system (TPMS) (not shown) that may serve as a system fault detector. The TPMS may be used to detect any fault in the self-inflation system of the tire assembly 10 and alert the user of such a condition.
The tire air maintenance system 10 may further incorporate a variable pressure pump groove 56 with one or more inwardly directed ridges or ribs 66 engaging and compressing a segment of the air tube 42 opposite such rib(s). The pitch or frequency of the ribs may increase toward the outlet device 70 for gradually reducing air volume within the passageway 43 by compressing the tube 42. The reduction in air volume may increase air pressure within the passageway 43 and thereby facilitate a more efficient air flow from the tube 42 into the tire cavity 40. The increase in tube pressure may be achieved by engagement by the ribs 66 of the groove 56 and the tube 42 having uniform dimensions along the tube length. The tube 42 may thus be made of uniform dimension and of relatively smaller size without compromising the flow pressure of air to the tire cavity 40 for maintaining air pressure. The pitch and amplitude of the ridges 66 may both be varied to better achieve the desired pressure increase within the passageway 43.
Structures in a pneumatic tire may require the embedding of certain rigid parts, functional devices, and/or connectors into adhering onto the rubber of the tire. For example, the structures 14, 42, 68, 70, 101, etc. of the example air maintenance tire 10 described above may require embedding/adherence. Such structures 14, 42, 68, 70, 101, etc. typically encounter high stresses during operating conditions of the tire 10. Thus, strong bonding of such structures 14, 42, 68, 70, 101, etc. is desired since a bond break at the structure's 14, 42, 68, 70, 101, etc. surface will likely lead to destruction of the assembly 14 and/or the integrity of the tire 12 as a whole.
For example, a polyamide elbow-like structure 70 may be bonded to a tire 10 in order to define a built-in tube-like cavity (
In order to optimally bond such structures 14, 42, 68, 70, 101, etc. to a tire 12, a subcoat and a topcoat may be applied to the structures. In accordance with the present invention, a compound cement of high stiffness may bond each structure 14, 42, 68, 70, 101, etc. to the tire 10 by creating a stiffness gradient from the structure to a less stiff repair gum that may be used to close the tube-like cavity dedicated to each structure. Such bond may be achieved by a subcoat, dried at 180 C for 8 min under air to a polyamide surface of the structure 14, 42, 68, 70, 101, etc., by a topcoat, dried at 180 C for 8 min under air over the subcoat, and a cement prepared from a homogenous slurry in a solvent (e.g. tetrahydrofurane) over the topcoat. This approach may bond polyamide structures 14, 42, 68, 70, 101, etc., as well as other thermoplastic structures.
Such bonds may be utilized for the structures 14, 42, 68, 70, 101, etc. described above (e.g., a built-in peristaltic pump approach, etc.), a core coating for valve cavities as described above, a core coating for particular hollow, rubber structures, etc. Further, such bonds may secure thermoplastic structures to rubber by application to green repair rubber prior to a post-cure step.
The structures 14, 42, 68, 70, 101, etc. may be treated with an aqueous emulsion comprising a polyepoxide, followed by treating the structures with an aqueous RFL emulsion comprising a resorcinol-formaldehyde resin, a styrene-butadiene copolymer latex, a vinylpyridine-styrene-butadiene terpolymer latex, and a blocked isocyanate. The structures 14, 42, 68, 70, 101, etc. may also be treated with an RFL (Resorcinol-Formaldehyde-Latex) dip. An adhesion activator, typically comprising a polyepoxide, may serve to improve adhesion of the structures 14, 42, 68, 70, 101, etc. to rubber compounds after a structure is dipped with an RFL dip. Such approaches may not be robust against long and/or high temperature cures in compounds that contain traces of humidity and amines, which may attack the skin of the structures and degrade the adhesive/structure interface. One sign of failure may be a nude structure 14, 42, 68, 70, 101, etc. showing only traces of adhesive left on it.
The structures 14, 42, 68, 70, 101, etc. may be treated with polyepoxide. The structures 14, 42, 68, 70, 101, etc. may then be dipped in an aqueous dispersion of a polyepoxide, also referred to herein as an epoxy or epoxy compound. The structures 14, 42, 68, 70, 101, etc. may be formed structures that have been treated with sizing or adhesives. Thus, the structures 14, 42, 68, 70, 101, etc. may also be subsequently treated using conventional methods.
As a polyepoxide, use may be made of reaction products between an aliphatic polyalcohol, such as glycerine, propylene glycol, ethylene glycol, hexane triol, sorbitol, trimethylol propane, 3-methylpentanetriol, poly(ethylene glycol), poly(propylene glycol) etc., and a halohydrine, such as epichlorohydrin, reaction products between an aromatic polyalcohol such as resorcinol, phenol, hydroquinoline, phloroglucinol bis(4-hydroxyphenyl)methane and a halohydrin, reaction products between a novolac-type phenolic resin such as a novolac type phenolic resin, and/or a novolac-type resorcinol resin and halohydrin. The polyepoxide may be derived from an ortho-cresol formaldehyde novolac resin.
The polyepoxide may be used as an aqueous dispersion of a fine particle polyepoxide. The polyepoxide may be present in the aqueous dispersion in a concentration range from about 1 percent by weight to about 5 percent by weight. The polyepoxide may be present in the aqueous dispersion in a concentration range from about 1 percent by weight to about 3 percent by weight. In a first treatment step, dry polyester structures 14, 42, 68, 70, 101, etc. cord may be dipped in the aqueous polyepoxide dispersion. The structures 14, 42, 68, 70, 101, etc. may be dipped for a time sufficient to allow a dip pick up, or DPU, of between about 0.3 percent by weight and 0.7 percent by weight of polyepoxide. The DPU may be between about 0.4 percent by weight and 0.6 percent by weight. The DPU may be defined as a dipped cord structure weight (after drying or curing of the dipped structure) minus the undipped structure weight, then divided by the undipped structure weight. The structures 14, 42, 68, 70, 101, etc. may be treated in the aqueous polyepoxide dispersion in a continuous process by drawing the structures through a dispersion bath, or by soaking the structures in batch. After dipping in the polyepoxide dispersion, the structures 14, 42, 68, 70, 101, etc. may be conventionally dried or cured to remove the excess water.
In a second treatment step, the polyepoxide treated structures 14, 42, 68, 70, 101, etc. may be dipped in a modified RFL liquid. The adhesive composition may be comprised of (1) resorcinol, (2) formaldehyde and (3) a styrene-butadiene rubber latex, (4) a vinylpyridine-styrene-butadiene terpolymer latex, and (5) a blocked isocyanate. The resorcinol may react with formaldehyde to produce a resorcinol-formaldehyde reaction product. This reaction product may be the result of a condensation reaction between a phenol group on the resorcinol and an aldehyde group on the formaldehyde. Resorcinol may resole and resorcinol-phenol may resole, whether formed in situ within the latex or formed separately in aqueous solution, may be considerably superior to other condensation products in the adhesive mixture.
The resorcinol may be dissolved in water, to which around 37 percent formaldehyde has been added, together with a strong base, such as sodium hydroxide. The strong base may generally constitute around 7.5 percent or less of the resorcinol, and the molar ratio of formaldehyde to resorcinol may be from about 1.5 to about 2. The aqueous solution of the resole or condensation product or resin may be mixed with the styrene-butadiene latex and vinylpyridine-styrene-butadiene terpolymer latex. The resole or other mentioned condensation product or materials that form the condensation product may constitute from 5 parts to 40 parts, or around 10 parts to 28 parts, solids of the latex mixture. The condensation product forming the resole or resole type resin forming materials may be partially reacted or fully reacted so as to be only partially soluble in water. Sufficient water may then be added to produce around 12 percent to 18 percent by weight overall solids in a final dip. The weight ratio of the polymeric solids from the latex to the resorcinol/formaldehyde resin may be in a range of about 2 to about 6.
The RFL adhesive may also include a blocked isocyanate. In one form, from about 1 part by weight to about 8 parts by weight of solids of blocked isocyanate may be added to the adhesive. The blocked isocyanate may be any suitable blocked isocyanate, known to be used in RFL adhesive dips, including, but not limited to, caprolactam blocked methylene-bis-(4-phenylisocyanate), such as Grilbond-IL6 available from EMS American Grilon, Inc., and phenol formaldehyde blocked isocyanates as disclosed in U.S. Pat. Nos. 3,226,276, 3,268,467, and 3,298,984, herein incorporated by reference. As a blocked isocyanate, use may be made of reaction products between one or more isocyanates and one or more kinds of isocyanate blocking agent. The isocyanates may include monoisocyanates, such as phenyl isocyanate, dichlorophenyl isocyanate, and naphthalene monoisocyanate; diisocyanate, such as tolylene diisocyanate, dianisidine diisocyanate, hexamethylene diisocyanate, m-phenylene diisocyanate, tetramethylene diisocyante, alkylbenzene diisocyanate, m-xylene diisocyanate, cyclohexylmethane diisocyanate, 3,3-dimethoxyphenylmethane-4,4′-diisocyanate, 1-alkoxybenzene-2,4-diisocyanate, ethylene diisocyanate, propylene diisocyanate, cyclohexylene-1,2-diisocyanate, diphenylene diisocyanate, butylene-1,2-diisocyanate, diphenylmethane-4,4-diisocyanate, diphenylethane diisocyanate, 1,5-naphthalene diisocyanate, etc.; and triisocyanates, such as triphenylmethane triisocyanate, diphenylmethane triisocyanate, etc. The isocyanate-blocking agents may include phenols, such as phenol, cresol, and resorcinol; tertiary alcohols, such as t-butanol and t-pentanol; aromatic amines, such as diphenylamine, diphenylnaphthylamine and xylidine; ethyleneimines, such as ethylene imine and propyleneimine; imides, such as succinic acid imide and phthalimide; lactams, such as epsilon-caprolactam, delta-valerolactam, and butyrolactam; ureas, such as urea and diethylene urea; and oximes, such as acetoxime, cyclohexanoxime, benzophenon oxime, and alpha-pyrolidon.
The polymers may be added in the form of a latex or otherwise. In one form, a vinylpyridine-styrene-butadiene terpolymer latex and styrene-butadiene rubber latex may be added to the RFL adhesive. The vinylpyridiene-styrene-butadiene terpolymer may be present in the RFL adhesive such that the solid weight of the vinylpyridiene-styrene-butadiene terpolymer is from about 50 percent to about 100 percent of the solid weight of the styrene-butadiene rubber; in other words, the weight ratio of vinylpyridiene-styrene-butadiene terpolymer to styrene-butadiene rubber may be from about 1 to about 2.
It may be preferable to first prepare the polymer latex and then add the partially condensed condensation product. However, the ingredients (the resorcinol and formaldehyde) may be added to the polymer latex in the uncondensed form and the entire condensation may then take place in situ. The latex may keep longer and be more stable if it is kept at an alkaline pH level.
The polyepoxide treated structures 14, 42, 68, 70, 101, etc. may be dipped from about one second to about three seconds in the RFL dip and dried at a temperature within the range from 120° C. to 265° C. for about 0.5 minutes to 4.0 minutes and thereafter placed in the rubber and cured therewith. The drying step utilized may be carried out by passing the structures 14, 42, 68, 70, 101, etc. through 2 or more drying ovens, which may be maintained at progressively higher temperatures. For example, the structures 14, 42, 68, 70, 101, etc. may be dried by passing them through a first drying oven, which is maintained at a temperature of about 121° C. to about 149° C., and then to a second oven, which is maintained at a temperature of about 177° C. to about 260° C. It should be appreciated that these temperatures are oven temperatures rather than the temperature of the structures 14, 42, 68, 70, 101, etc. being dried. The structures 14, 42, 68, 70, 101, etc. may have a total residence time in the drying ovens within the range of about 1 minute to about 5 minutes. For example, a residence time of 30 seconds to 90 seconds in the first oven, and 30 seconds to 90 seconds in the second oven, may be employed.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative examples and details have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the scope of the present invention. It is, therefore, to be understood that changes may be made in the particular examples described which will be within the full intended scope of the present invention as defined by the following appended claims.
