CA1071785A - Puncture sealing composition and tire - Google Patents
Puncture sealing composition and tireInfo
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- CA1071785A CA1071785A CA246,948A CA246948A CA1071785A CA 1071785 A CA1071785 A CA 1071785A CA 246948 A CA246948 A CA 246948A CA 1071785 A CA1071785 A CA 1071785A
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Abstract
ABSTRACT OF THE DISCLOSURE
A pneumatic tire of the tubeless type, em-bodying a layer of puncture sealant composition based on a major proportion of low molecular weight liquid elastomer with a minor proportion of a high molecular weight elastomer, containing a crosslinking agent in an amount sufficient to give a partial cure. An ex-sample of the composition of the invention is a blend of 60 parts of depolymerized natural rubber and 40 parts of cis-polyisoprene, partially crosslinked by the provide a gel content of about 40%.
A pneumatic tire of the tubeless type, em-bodying a layer of puncture sealant composition based on a major proportion of low molecular weight liquid elastomer with a minor proportion of a high molecular weight elastomer, containing a crosslinking agent in an amount sufficient to give a partial cure. An ex-sample of the composition of the invention is a blend of 60 parts of depolymerized natural rubber and 40 parts of cis-polyisoprene, partially crosslinked by the provide a gel content of about 40%.
Description
~ ` 1071785 mis invention relates to a puncture sealing composition and to a pneumatic tire of the tubeless type embodying a layer of puncture sealant cornposi-tion based on a mixture of more than 50~ low molecu-lar weight liquid ru~ber, a high molecular weight elastomer, and an amount of crosslinking agent ~or the mixture, sufficient to give partial crosslinking.
Puncture sealing tubeless tires have previously been proposed, containing, in the area of the tire nor-mally most subject to punctures ~that is, the under-tread or the area extending across the crown of the -tire at least from one shoulder to the other), a layer of sealant composition which has plastic and adhesive qualities such that the composition tends to stick to a puncturing object, and, when the puncturing ob~ect i !
is withdrawn, tends to flow into the opening or punc-; ture, forming a plug which seals the opening against ; loss of air from the tires. Unfortunately, it has proven difficult to provide a composition which would y ~ 20 flow into the puncture hole and yet have sufficientviscosity to prevent it from flowing at ele~ated tem-peratures, up to 250F., such as exist in an automobile pneumatic tire under operating conditions. The problem is complicated by the extreme centrifugal force to 25~ which the composition is subjected as the tire rotates ,, ' ~ .
, . .1 ' ' :
at high speed, since such centrifugal force tends to cause the composition to flow into the central crown area, leaving the areas near the shoulders unprotected.
Furthermore, it has proven di~ficult to provide a seal-ant composition which would retain this desired balance of viscosity, plasticity, adhesion and conformability over an extended period of service.
mere are a number o~ patents that employ un-vulcanized, partially vulcanized or fully vulcanized elastomeric layers as puncture sealants in pneumatic tires. Among them are U. S. patent 2,782,829, Peter-son et al., ~ebruary 26, 1957; Canadian patents ; 572,794, Peterson et al., March 24, 1959, and 572,799, Iknayan et al., March 24, 1959. Some of these include minor amounts of plasticizers or soften-ers such as mineral oil, rosin oil, cumarone-indene resins or liquid polybutene. Such materials however, remain in the wholly uncured condition and do not function as essential components of the sealant.
The present invention employs major amounts, at least more than 50%, of a liquid elastomer which is an es-sential part of the sealant mixturs and is partially covulcanized with the high molecular weight solid elast-omer. The resultant composition is unique in that the high molecular weight partially vulcanized portion ser-ves as a gelled matrix which restrains the low molecular weight portion from flowing at elevated temperature and
Puncture sealing tubeless tires have previously been proposed, containing, in the area of the tire nor-mally most subject to punctures ~that is, the under-tread or the area extending across the crown of the -tire at least from one shoulder to the other), a layer of sealant composition which has plastic and adhesive qualities such that the composition tends to stick to a puncturing object, and, when the puncturing ob~ect i !
is withdrawn, tends to flow into the opening or punc-; ture, forming a plug which seals the opening against ; loss of air from the tires. Unfortunately, it has proven difficult to provide a composition which would y ~ 20 flow into the puncture hole and yet have sufficientviscosity to prevent it from flowing at ele~ated tem-peratures, up to 250F., such as exist in an automobile pneumatic tire under operating conditions. The problem is complicated by the extreme centrifugal force to 25~ which the composition is subjected as the tire rotates ,, ' ~ .
, . .1 ' ' :
at high speed, since such centrifugal force tends to cause the composition to flow into the central crown area, leaving the areas near the shoulders unprotected.
Furthermore, it has proven di~ficult to provide a seal-ant composition which would retain this desired balance of viscosity, plasticity, adhesion and conformability over an extended period of service.
mere are a number o~ patents that employ un-vulcanized, partially vulcanized or fully vulcanized elastomeric layers as puncture sealants in pneumatic tires. Among them are U. S. patent 2,782,829, Peter-son et al., ~ebruary 26, 1957; Canadian patents ; 572,794, Peterson et al., March 24, 1959, and 572,799, Iknayan et al., March 24, 1959. Some of these include minor amounts of plasticizers or soften-ers such as mineral oil, rosin oil, cumarone-indene resins or liquid polybutene. Such materials however, remain in the wholly uncured condition and do not function as essential components of the sealant.
The present invention employs major amounts, at least more than 50%, of a liquid elastomer which is an es-sential part of the sealant mixturs and is partially covulcanized with the high molecular weight solid elast-omer. The resultant composition is unique in that the high molecular weight partially vulcanized portion ser-ves as a gelled matrix which restrains the low molecular weight portion from flowing at elevated temperature and
-2-"`` 1C~717~
high centrifugal forces and yet permits sufficient con~ormability for the composition to funckion ef~ec-tively as a puncture sealant U. S. patent 2,657,729,Hardman et al., November
high centrifugal forces and yet permits sufficient con~ormability for the composition to funckion ef~ec-tively as a puncture sealant U. S. patent 2,657,729,Hardman et al., November
3, 1953, disclo~es a puncture sealant based on depoly-merized rubber and a gelling agent. Unlike the present sealant, the H~rdman et al. composition does not include a partially covulcanized high molecular weight solid elastomer.
Japanese patent No~ 82796/72 of Brldgestone, April 13, 1974, teaches the use of blends of high and low molecular weight elastomers such as EPDM and polybutene, the non-flowing property of which is imparted by the - inclusl~ of short nylon fibers. In one example which describes the use of an envelope to contain the puncture ; sealant material a small amount, 0.5 phr, of sulfur is ~dded to the composition. This amount of sulfur is in-sufficient to be operative in the present invention.
The present sealant composition, in contrast, contains sufficient curative to produce resistance to flow;
fibrous restralnt is neither neces6ary nor desirable ln the present composition, which is preferably devoid of fibrous filler.
Accordingly, in the prior art, various elastomers, both cured and uncured, have been proposed as puncture sealants. In the uncured state, although they may func-tion as sealants, they will sometimes tend to "cold flow"
or flow at elevated temperatures such as are encountered in tires during use. Thls flow is undesirable. When they are crosslinked (cured) to prevent flow, these 10'71785 .. .. .
.
materlals sometimes then tend to lose the adhesion and conform~billty of the uncured ~tate, and no longer act as sealants.
We have found that a mixture of high and low molecular weight elastomer, the latter being present ln amount of more than 50% by weight, cured to a limited extent, sufficient to prevent flow under conditions of use, o~fers novel and unique advantages. The high mole-cular weight elastomer furnlshes rigidity and strength.
; 10 The low m~lecular weight elastomer furnishes the adhesion and conformability necessary in a puncture sealant. The tendency to flow is, of course, greatest in the low mole-cular weight component. By increasing the proportion of high molecular weight component, this tendency can be de-creased, but not completely removed.~ In partially curing the mixture, the crosslinks are more effective in the . .
- high molecular weight elastomer, thus allowing it to act as a supporting structure or skeleton to retard flow, without crosslinking the low molecular weight elastomer to the point where its ability to ~unction as sealant would be signlficantly impaired.
The invention will be described with reference to the accompanying drawing, wherein:
~ Fig. 1 i8 a largely diagrammatic sectional ele- -vational view of a pneumatic tire embodying a puncture i sealant layer in accordance with the invention;
Figs. 2 and 3 are enlarged fragmentary views similar to Figure 1 illustrating the sealing action of the puncture sealant layer; and Fig. 4 is a view similar to Figure 1 showing a .~
_4_ -10~1~85 modification of the inventlon, As ~ndicated, the invention is a puncture sealant composition which ls a mixture o~ low molecular weight liquid elastomer with a high molecular weight elastomer being present in amount greater than 50~, based on the weight of the two polymers, crosslinked to an extent, as measured by gel and Mooney viscosity, which will pre-vent it from flowing at elevated temperature, yet still possess sufficient adhesion and conformability to func-tion as a sealant.
As the high molecular weight elastomeric com-ponent of the sealant composition of the invention there may be employed any high molecular weight solid elastomer capable of belng crosslinked. Examples are the highly unsaturated rubbers such as those based on conJugated diolefins, whether homopolymers as in polyisoprene (par-ticularly cis-polyisoprene, whether natural or synthetic), polybutadiene (including polybutadiene of high cis con-tent), polychloroprene (neoprene), or copolymers as exemplified by those havlng a major proportion of such con~ugated dienes as butadiene with a mlnor proportion of such monoethylenically unsaturated copolymerizable monomers as styrene or acrylonitrile. Alternatively, elastomers of low unsaturation may be used, notably butyl type rubbers (copolymers of such isoolefins as iso-butylene with small amounts of conjugated dienes such as isoprene), or the EPDM types (copolymers of at least two different monoolefins such as ethylene and propylene with a small amount of a non-con~ugated diene such as dicyclopentadiene, 1,4-hexadiene~ 5-ethylidene-2-nor-, ~
. .
J ~ .
- : -bornene, etc.). Even s~turated elastomers such as EPM
or ethylenervl3yl acetate may be employed-, using the proper cure system. me elastomer may be emulsion-prepared or solution-prepared, stereo specific or other-wise. The molecular weight of the solid elastomer is usually in excess o~ 5?,, ordinarily within the range of from 60,000 to 2 or 3 million or more. Ordlnarlly ; the solid elastomeric component has a Mooney viscosity wit~n ~hc range of from 20 to 160 ML-4 at 212F.
The low molecular weight elastomer employed has a molecular weight less than 50,000, usually within the range from 1,000 to 10,000, and is preferably of the "liquid" rubber type with a maximum Brookfield viscosity at 150F. of 200,000 cps~, ordinarily within the range of from 20,000 to 200,000 cps. Examples are: liquid cis-polyisoprene (e.g., heat depolymerized natural rubber, ; or cis-polyisoprene polymerized to low molecular weight), liquid polybutadiene, liquid polybutene, liquid EPDM, and llquid butyl rubber. The high molecular weight, elongation and film strength of cis-polyisoprene (both natural and synthetic) and great tackiness of depoly-merized cis-polyisoprene give a combination of these two elastomers, whe~ partially cured, according to the pre-sent invention, a large degree of resistance to flow~
coupled with efficient sealing ability. Other elasto-- mer combinations of the present invention, particularly the saturated ones, offer resistance to oxidation in service which makes them also highly desirable.
~ The sealant composition of the invention containsJ., ~ 30 a ma~or proportion, that is, between more than 50~ and 90 `.
.
by weight of the low molecular weight elastomer based on the weight o~ the two elasto~ers, depending mainly on the molecular weight of the high molecular welght elastomer and other variables such as the particular elastomer involved, the amount and kind of crosslinking agent, and the conditions of the crosslinking treatment.
; Ordinarily the proportion of the two elastomeric com-ponents are chosen so as to give an initial Mooney vis-; cosity at room temperature (the initial peak reading attained, whlch is usually within the first few seconds) of between 30 and 70 (large rotor, ML) in the final crosslinked mixture, ~ith a preferred range of 40 to 60. Below the aforementioned initial Mooney viscosity of 30, the composition will tend tO fiow down from the shoulder and sidewall areas of the tire when it is run at high speed as well as out of the hole when the tire ls punctured. Above the said initial Mooney viscosity of 70, the sealant capability of the composition is sufficiently impaired to render it unuseable for prac-tlcal purposes. The Mooney viscosity of the mixture can also be controlled for a given elastomeric composi-tion o~ the present invention by the amount of the mechanical ~hearing employed in mixing the constituents.
The net effect here, of course, is to break down (i.e., lower) the molecular weight of the high molecular weight ; component, thereby lowering the Mooney viscosity before cure.
As indicated, for p~rposes of the invention the mixture further includes a crosslinking agent.
The crosslinking agent may be any suitable substance , . ~
~ -7-~,,~,...
,,: ,. . . . .. - ~
107~785 or combination of substances capable of curlng or gell-ing the mixture to the desired extent. Examples are:
1) Sulfur curing systems such as those based on sulfur or sulfur-yielding materials (e.g., tetra-methyl thiuram disulfide) and conventional accelerators of sulfur vulcanization.
2) Quinoid curing systems such as p-quinone dioxime (GMF, trademark; Uniroyal Chemical) with or without supplementary oxidant.
3) Organic peroxides (or hydroperoxides) such as dicumyl peroxide, cumene hydroperoxide, methyl ethyl ketone hydroperoxide or other radical generating cata-lysts such as azobisisobutyronitrile.
Japanese patent No~ 82796/72 of Brldgestone, April 13, 1974, teaches the use of blends of high and low molecular weight elastomers such as EPDM and polybutene, the non-flowing property of which is imparted by the - inclusl~ of short nylon fibers. In one example which describes the use of an envelope to contain the puncture ; sealant material a small amount, 0.5 phr, of sulfur is ~dded to the composition. This amount of sulfur is in-sufficient to be operative in the present invention.
The present sealant composition, in contrast, contains sufficient curative to produce resistance to flow;
fibrous restralnt is neither neces6ary nor desirable ln the present composition, which is preferably devoid of fibrous filler.
Accordingly, in the prior art, various elastomers, both cured and uncured, have been proposed as puncture sealants. In the uncured state, although they may func-tion as sealants, they will sometimes tend to "cold flow"
or flow at elevated temperatures such as are encountered in tires during use. Thls flow is undesirable. When they are crosslinked (cured) to prevent flow, these 10'71785 .. .. .
.
materlals sometimes then tend to lose the adhesion and conform~billty of the uncured ~tate, and no longer act as sealants.
We have found that a mixture of high and low molecular weight elastomer, the latter being present ln amount of more than 50% by weight, cured to a limited extent, sufficient to prevent flow under conditions of use, o~fers novel and unique advantages. The high mole-cular weight elastomer furnlshes rigidity and strength.
; 10 The low m~lecular weight elastomer furnishes the adhesion and conformability necessary in a puncture sealant. The tendency to flow is, of course, greatest in the low mole-cular weight component. By increasing the proportion of high molecular weight component, this tendency can be de-creased, but not completely removed.~ In partially curing the mixture, the crosslinks are more effective in the . .
- high molecular weight elastomer, thus allowing it to act as a supporting structure or skeleton to retard flow, without crosslinking the low molecular weight elastomer to the point where its ability to ~unction as sealant would be signlficantly impaired.
The invention will be described with reference to the accompanying drawing, wherein:
~ Fig. 1 i8 a largely diagrammatic sectional ele- -vational view of a pneumatic tire embodying a puncture i sealant layer in accordance with the invention;
Figs. 2 and 3 are enlarged fragmentary views similar to Figure 1 illustrating the sealing action of the puncture sealant layer; and Fig. 4 is a view similar to Figure 1 showing a .~
_4_ -10~1~85 modification of the inventlon, As ~ndicated, the invention is a puncture sealant composition which ls a mixture o~ low molecular weight liquid elastomer with a high molecular weight elastomer being present in amount greater than 50~, based on the weight of the two polymers, crosslinked to an extent, as measured by gel and Mooney viscosity, which will pre-vent it from flowing at elevated temperature, yet still possess sufficient adhesion and conformability to func-tion as a sealant.
As the high molecular weight elastomeric com-ponent of the sealant composition of the invention there may be employed any high molecular weight solid elastomer capable of belng crosslinked. Examples are the highly unsaturated rubbers such as those based on conJugated diolefins, whether homopolymers as in polyisoprene (par-ticularly cis-polyisoprene, whether natural or synthetic), polybutadiene (including polybutadiene of high cis con-tent), polychloroprene (neoprene), or copolymers as exemplified by those havlng a major proportion of such con~ugated dienes as butadiene with a mlnor proportion of such monoethylenically unsaturated copolymerizable monomers as styrene or acrylonitrile. Alternatively, elastomers of low unsaturation may be used, notably butyl type rubbers (copolymers of such isoolefins as iso-butylene with small amounts of conjugated dienes such as isoprene), or the EPDM types (copolymers of at least two different monoolefins such as ethylene and propylene with a small amount of a non-con~ugated diene such as dicyclopentadiene, 1,4-hexadiene~ 5-ethylidene-2-nor-, ~
. .
J ~ .
- : -bornene, etc.). Even s~turated elastomers such as EPM
or ethylenervl3yl acetate may be employed-, using the proper cure system. me elastomer may be emulsion-prepared or solution-prepared, stereo specific or other-wise. The molecular weight of the solid elastomer is usually in excess o~ 5?,, ordinarily within the range of from 60,000 to 2 or 3 million or more. Ordlnarlly ; the solid elastomeric component has a Mooney viscosity wit~n ~hc range of from 20 to 160 ML-4 at 212F.
The low molecular weight elastomer employed has a molecular weight less than 50,000, usually within the range from 1,000 to 10,000, and is preferably of the "liquid" rubber type with a maximum Brookfield viscosity at 150F. of 200,000 cps~, ordinarily within the range of from 20,000 to 200,000 cps. Examples are: liquid cis-polyisoprene (e.g., heat depolymerized natural rubber, ; or cis-polyisoprene polymerized to low molecular weight), liquid polybutadiene, liquid polybutene, liquid EPDM, and llquid butyl rubber. The high molecular weight, elongation and film strength of cis-polyisoprene (both natural and synthetic) and great tackiness of depoly-merized cis-polyisoprene give a combination of these two elastomers, whe~ partially cured, according to the pre-sent invention, a large degree of resistance to flow~
coupled with efficient sealing ability. Other elasto-- mer combinations of the present invention, particularly the saturated ones, offer resistance to oxidation in service which makes them also highly desirable.
~ The sealant composition of the invention containsJ., ~ 30 a ma~or proportion, that is, between more than 50~ and 90 `.
.
by weight of the low molecular weight elastomer based on the weight o~ the two elasto~ers, depending mainly on the molecular weight of the high molecular welght elastomer and other variables such as the particular elastomer involved, the amount and kind of crosslinking agent, and the conditions of the crosslinking treatment.
; Ordinarily the proportion of the two elastomeric com-ponents are chosen so as to give an initial Mooney vis-; cosity at room temperature (the initial peak reading attained, whlch is usually within the first few seconds) of between 30 and 70 (large rotor, ML) in the final crosslinked mixture, ~ith a preferred range of 40 to 60. Below the aforementioned initial Mooney viscosity of 30, the composition will tend tO fiow down from the shoulder and sidewall areas of the tire when it is run at high speed as well as out of the hole when the tire ls punctured. Above the said initial Mooney viscosity of 70, the sealant capability of the composition is sufficiently impaired to render it unuseable for prac-tlcal purposes. The Mooney viscosity of the mixture can also be controlled for a given elastomeric composi-tion o~ the present invention by the amount of the mechanical ~hearing employed in mixing the constituents.
The net effect here, of course, is to break down (i.e., lower) the molecular weight of the high molecular weight ; component, thereby lowering the Mooney viscosity before cure.
As indicated, for p~rposes of the invention the mixture further includes a crosslinking agent.
The crosslinking agent may be any suitable substance , . ~
~ -7-~,,~,...
,,: ,. . . . .. - ~
107~785 or combination of substances capable of curlng or gell-ing the mixture to the desired extent. Examples are:
1) Sulfur curing systems such as those based on sulfur or sulfur-yielding materials (e.g., tetra-methyl thiuram disulfide) and conventional accelerators of sulfur vulcanization.
2) Quinoid curing systems such as p-quinone dioxime (GMF, trademark; Uniroyal Chemical) with or without supplementary oxidant.
3) Organic peroxides (or hydroperoxides) such as dicumyl peroxide, cumene hydroperoxide, methyl ethyl ketone hydroperoxide or other radical generating cata-lysts such as azobisisobutyronitrile.
4) Polyisocyanates such as MDI (4,4'-methylene bis-phenyleneisocyanate)5 TDI (tolylene diisocyanate), and PAPI (polymethylene polyphenylisocyanate) as well a~ dimers and trimers of MDI and TDI.
5) Tetrahydrocarbyl titanate esters.
e amount of crosslinking agent employed will ; 20 vary with the particular elastomers employed and with their proportions, as well as with the particular cross-linking agent and the conditions of the crosslinking step. Ordinarily the amount used is that sufficient to prevent flow of the composition in a tire at temperatures up to 200F. and speeds up to 50 mph, while still retain-ing sufficient adhesiveness and conformability to per-form the described sealant function. me amounts em-ployed will vary depending on the proportion of high ..
.:
~, ~' :
~: :
107~785 molecular weight elastomer inithe mixture. Higher pro-portlons of high molecular welght elastomer will requlre less crossllnklng agent and vlce-versa to malntain the desired combination of reslstance to flow and seallng ablli~y. The amoùnt of cros811nking agent will, of course, vary wlth the nature of the elastom~rs themselves. ~or a depolymerlZed natural rubber (DPR)-natural rubber (NR) mlxture, the amount of sulfur-containing or qulnold type cur~tlve wlll be in the range of from msre than 0.5 to 2 0 phr (part9 per 100 parts by weight of both elastomers added together), ordlnarily from 0.7 to 1.5 phr. For this same mixture, wlth polylsocyanate or hydrocarbyl titanate ester curatives, the amounts required will ordlnarily be in the range from about 2 to 10 phr, preferably 3 to 8 phr. Similarly, the applicable range for peroxide or hydroperoxlde curatives (radlcal generating catalysts) would be 0.1 to 1.0 phr, preferably 0.2 to 0.7 phr.
The crosslinking o~ the sealant mixture is accompanied by an increase ln viscosity and an lncrease in the gel content ~content of insoluble materlal). It has been found that for the natural rubber, depolymerized natural rubber mixture, a gel content~ as measured in toluene at room temperature, of between 15 to 60%, preferably 20 to 50%, by welgh~, in the crosslinked blend correlates with the desirable combinatlon of seal-ing ability and lack of flow properties. For other L ' elaBtomer combinations the range of optimum gel content w~ll vary depending on the molecular weight and proper- ;
t~on of the two elastomeric components. As described prevlously, an lnitial Mooney viscosity (ML at room temperature) of between 30 and 70 of the f~nal _9_ ~' ~ . . . . ' ~071785 ~ -10-cured mlxture has been found to correlate with the a~orementioned desired comblnation of properties.
The crosslinking may be carried out at ordinary ambient temperature or at elevated temperature, depend-ing on the temperature at whic~ the particular cross-linking system selected is active in the particular elastomer combination employed.
The composition may further include, lf desired, ~ . .
various appropriate additional compounding ingredients such as pigments such as carbon black, particulate in-organic fillers, extenders, tackifiers, ctabilizers and antioxidants. It is not necessary nor desirable to add flbrous fillers to the present compositlons.
In practicing the invention the ingredients are mlxed together uniformly and the resulting mixture is-incorporated in the tire in the form of a relatlvely thin (e.g. 0.1 lnch) sealant layer. Referrlng to the ~i drawing, and particularly to Flg. 1, a typical embodi-ment of the invention comprises a toroidal tubeless tire casing 10 having the usual vulcanized rubber tread ;
11 and sidewall portions 12, 13 surmounting a vulcanized ~; rubber carcass 14 reinforced with filamentary material, ~ -which terminates at bead areas 15, 16 containing the usual circumferential inextensible reinforcement. m e entire inside surface of the carcass is covered by the usual air-impervious liner 17. A layer 18 of seal-ant material of the invention extends across the interior crown surface of the liner from one shoulder area of ; the tire to the other~ and extends at least part way into each interior side wall area.
,....
The sealing action of the layer 18 is re~
presented in Fig. 2 and 3, wherein Fig. 2 shows a nail 19 puncturing the tire through the tread 11, car~
cass 14, liner 17 and sealant layer 18. The sealant composition tends to adhere to the nail and prevents 109s of air pressure while the nail is in place. When the nail is withdrawn, as shown in Fig. 3,it tends to pull a plug 20 of the sealant composition into the puncture 21, thereby sealing the puncture against loss of air.
In am~fication of the invention, as shown in Fig. 4, the puncture sealant layer 23 of the in-vention is disposed in between the inner surface of the carcass 24 and the liner 25. In such cases where the sealant layer is lncorporated in the tlre, it may be crosslinked before or after said incorporation.
Similarly, the tire may be cured before or after in-corporation of the sealant layer.
In order to apply a sealant layer to the in-terior surface of a tire, the composltion may be pre-pared as a solvent cement, for example as a solution in n-hexane or other suitable volatlle organic solvent.
i Thls cement may be applled (e.g. sprayed or brushed) ` over the desired area of the inner surface of the tire liner, using as many coats as required to build up a desired thickness. Using the hydrocarbyl titanate curative system, the thus-applied sealant layer will ; become sufflciently crosslinked to perform the sealant function in about five days at room temperature, al-though the cure time may be shortened if desired by ' -11-.~
; 1071'785 storlng the tire in a warm place, e.g.~ at 50 to 100C.
Another method is to extrude the hea~ed sealant composltion into a tire at elevated temperature in the form of a layer or strip having the desired thick-nes~. Conveniently the composition may be extruded ; directly onto the liner surface from a suitably shaped die extendlng into the tire carcass, whilè rotating - the tire. For extrusion at elevated temperatures, a curatlve system must be selected which will not react prematurely at the temperature o~ extruslon, but which will subsequently cure the composition at some tempera-ture~higher than the extrusion temperature. me tetra-hydrocarbyl titanate ester cure of the puncture sealant ; represents a particularly advantageous practice of the invention in that with the tetrahydrocarbyl titanate ester curative it is possible to extrude the sealant at an elevated temperature without premature cure, and yet the cure of the applied sealant layer can be accom-- pllshed at a lower temperature (e.g. room temperature).
me reason for this is that the titanate ester cure of the blend of elastomers will not take place unless hy-drocarbyl alcohol (apparently formed as a by-product of '~;; the curing reaction) can escape from the composition.
,~
~~ If the material is confined under non-evaporative con-ditions (e.g. in the barrel of an extruder) the cure will not take place, even at elevated temperature. How-~ -, ,~; ever, aiter the blend is applied to the tlre, the said ~` hydrocarbyl alcohol is free to evaporate from the seal-; ant layer, and the cure proceeds, even without any necessity for heating.
; ~ -12-~lternatively, a previously prepared s~rip (e.g an extruded strip) of sealant composition of suitable width and thickness may be applied by any sultable means to the interior of a tire.
The puncture sealing layer may if desired cover the entire interior surface o~ the tire from one bead or rim area to the other, in which case the liner may be omitted and the puncture sealing layer may serve as a liner.
In some cases it may be desirable to in-corporate the sealant strip in the tire assembly as the tlre ls being manufactured~ for example by laying down a strip of the sealant material on a tire building drum, and then superimposing the liner and other carcass com-~` 15 ponents. m e sealant layer may be prevented from ad-hering to the building drum by first placing a layer of fIexible material on the drum followed by the seal-ant layer and then the remaining components of the tire.
Thus the liner may first be placed on the ~lre build-ing drum, followed by the sealant layer and carcass plies, : ... 1 to providè the type of construction shown in Fig. 4.
The puncture sealant abillty and resistance to ~ - flow of the composition of the invention may be tested .~ in an inflated tire. For this purpose the sealant is placed in the tire w~ich is run at 75 to 90 mph and !
a load sufficient to generate an internal temperature of 250F or higher. After running at hi~h speed the tire is then observed to determine whether the sealant ~ .
has flowed out of the shoulders of the tire and into the crown area or whether it has formed a puddle in the ~071785 -.14-bottom of the tlre after the tire was stopped. The ab~lity to resi~t flow at least 50 mph at an internal ; alr temperature of at least 200F is an important criterlon of performance for the present invention.
To evaluate puncture sealant ability, the tire is punctured with nalls of varlou9 sizes, which are subsequently removed from the tire, and the loss of air pressure wlthin the tire measured.~ Another impo~n~ ad~ant~ge of the present invention is the ablllty o~ the sealant compo~ition to seal holes of at least 0.125 inche in diameter.
The following example will serve to 111ustrate the practice of the inventlon in more detail.
1 ~80 grams of natural rubber (Standard Malaysian - 15 Rubber, Mooney viscosity 64 ML-4-212F., weight average ~
; molecular weight 4.7 x 10 ) was dissolved in 4 gallons r of n-hexane. To this solution was added 960 grams o~ depolymerized natural rubber (DPR-400 [trademark], ~- Hardman Company, viscosity 80,000 cps~150F.) and the~mixture stirred until it is uniform. 100.8 grams of tetra-n-butyl titanate was added and the cement .
~;~ stirred once more. 24 grams of Antioxidant 2246 [trade-mark, American Cyanamid, 2,2'-methylene-bis(4-methyl-
e amount of crosslinking agent employed will ; 20 vary with the particular elastomers employed and with their proportions, as well as with the particular cross-linking agent and the conditions of the crosslinking step. Ordinarily the amount used is that sufficient to prevent flow of the composition in a tire at temperatures up to 200F. and speeds up to 50 mph, while still retain-ing sufficient adhesiveness and conformability to per-form the described sealant function. me amounts em-ployed will vary depending on the proportion of high ..
.:
~, ~' :
~: :
107~785 molecular weight elastomer inithe mixture. Higher pro-portlons of high molecular welght elastomer will requlre less crossllnklng agent and vlce-versa to malntain the desired combination of reslstance to flow and seallng ablli~y. The amoùnt of cros811nking agent will, of course, vary wlth the nature of the elastom~rs themselves. ~or a depolymerlZed natural rubber (DPR)-natural rubber (NR) mlxture, the amount of sulfur-containing or qulnold type cur~tlve wlll be in the range of from msre than 0.5 to 2 0 phr (part9 per 100 parts by weight of both elastomers added together), ordlnarily from 0.7 to 1.5 phr. For this same mixture, wlth polylsocyanate or hydrocarbyl titanate ester curatives, the amounts required will ordlnarily be in the range from about 2 to 10 phr, preferably 3 to 8 phr. Similarly, the applicable range for peroxide or hydroperoxlde curatives (radlcal generating catalysts) would be 0.1 to 1.0 phr, preferably 0.2 to 0.7 phr.
The crosslinking o~ the sealant mixture is accompanied by an increase ln viscosity and an lncrease in the gel content ~content of insoluble materlal). It has been found that for the natural rubber, depolymerized natural rubber mixture, a gel content~ as measured in toluene at room temperature, of between 15 to 60%, preferably 20 to 50%, by welgh~, in the crosslinked blend correlates with the desirable combinatlon of seal-ing ability and lack of flow properties. For other L ' elaBtomer combinations the range of optimum gel content w~ll vary depending on the molecular weight and proper- ;
t~on of the two elastomeric components. As described prevlously, an lnitial Mooney viscosity (ML at room temperature) of between 30 and 70 of the f~nal _9_ ~' ~ . . . . ' ~071785 ~ -10-cured mlxture has been found to correlate with the a~orementioned desired comblnation of properties.
The crosslinking may be carried out at ordinary ambient temperature or at elevated temperature, depend-ing on the temperature at whic~ the particular cross-linking system selected is active in the particular elastomer combination employed.
The composition may further include, lf desired, ~ . .
various appropriate additional compounding ingredients such as pigments such as carbon black, particulate in-organic fillers, extenders, tackifiers, ctabilizers and antioxidants. It is not necessary nor desirable to add flbrous fillers to the present compositlons.
In practicing the invention the ingredients are mlxed together uniformly and the resulting mixture is-incorporated in the tire in the form of a relatlvely thin (e.g. 0.1 lnch) sealant layer. Referrlng to the ~i drawing, and particularly to Flg. 1, a typical embodi-ment of the invention comprises a toroidal tubeless tire casing 10 having the usual vulcanized rubber tread ;
11 and sidewall portions 12, 13 surmounting a vulcanized ~; rubber carcass 14 reinforced with filamentary material, ~ -which terminates at bead areas 15, 16 containing the usual circumferential inextensible reinforcement. m e entire inside surface of the carcass is covered by the usual air-impervious liner 17. A layer 18 of seal-ant material of the invention extends across the interior crown surface of the liner from one shoulder area of ; the tire to the other~ and extends at least part way into each interior side wall area.
,....
The sealing action of the layer 18 is re~
presented in Fig. 2 and 3, wherein Fig. 2 shows a nail 19 puncturing the tire through the tread 11, car~
cass 14, liner 17 and sealant layer 18. The sealant composition tends to adhere to the nail and prevents 109s of air pressure while the nail is in place. When the nail is withdrawn, as shown in Fig. 3,it tends to pull a plug 20 of the sealant composition into the puncture 21, thereby sealing the puncture against loss of air.
In am~fication of the invention, as shown in Fig. 4, the puncture sealant layer 23 of the in-vention is disposed in between the inner surface of the carcass 24 and the liner 25. In such cases where the sealant layer is lncorporated in the tlre, it may be crosslinked before or after said incorporation.
Similarly, the tire may be cured before or after in-corporation of the sealant layer.
In order to apply a sealant layer to the in-terior surface of a tire, the composltion may be pre-pared as a solvent cement, for example as a solution in n-hexane or other suitable volatlle organic solvent.
i Thls cement may be applled (e.g. sprayed or brushed) ` over the desired area of the inner surface of the tire liner, using as many coats as required to build up a desired thickness. Using the hydrocarbyl titanate curative system, the thus-applied sealant layer will ; become sufflciently crosslinked to perform the sealant function in about five days at room temperature, al-though the cure time may be shortened if desired by ' -11-.~
; 1071'785 storlng the tire in a warm place, e.g.~ at 50 to 100C.
Another method is to extrude the hea~ed sealant composltion into a tire at elevated temperature in the form of a layer or strip having the desired thick-nes~. Conveniently the composition may be extruded ; directly onto the liner surface from a suitably shaped die extendlng into the tire carcass, whilè rotating - the tire. For extrusion at elevated temperatures, a curatlve system must be selected which will not react prematurely at the temperature o~ extruslon, but which will subsequently cure the composition at some tempera-ture~higher than the extrusion temperature. me tetra-hydrocarbyl titanate ester cure of the puncture sealant ; represents a particularly advantageous practice of the invention in that with the tetrahydrocarbyl titanate ester curative it is possible to extrude the sealant at an elevated temperature without premature cure, and yet the cure of the applied sealant layer can be accom-- pllshed at a lower temperature (e.g. room temperature).
me reason for this is that the titanate ester cure of the blend of elastomers will not take place unless hy-drocarbyl alcohol (apparently formed as a by-product of '~;; the curing reaction) can escape from the composition.
,~
~~ If the material is confined under non-evaporative con-ditions (e.g. in the barrel of an extruder) the cure will not take place, even at elevated temperature. How-~ -, ,~; ever, aiter the blend is applied to the tlre, the said ~` hydrocarbyl alcohol is free to evaporate from the seal-; ant layer, and the cure proceeds, even without any necessity for heating.
; ~ -12-~lternatively, a previously prepared s~rip (e.g an extruded strip) of sealant composition of suitable width and thickness may be applied by any sultable means to the interior of a tire.
The puncture sealing layer may if desired cover the entire interior surface o~ the tire from one bead or rim area to the other, in which case the liner may be omitted and the puncture sealing layer may serve as a liner.
In some cases it may be desirable to in-corporate the sealant strip in the tire assembly as the tlre ls being manufactured~ for example by laying down a strip of the sealant material on a tire building drum, and then superimposing the liner and other carcass com-~` 15 ponents. m e sealant layer may be prevented from ad-hering to the building drum by first placing a layer of fIexible material on the drum followed by the seal-ant layer and then the remaining components of the tire.
Thus the liner may first be placed on the ~lre build-ing drum, followed by the sealant layer and carcass plies, : ... 1 to providè the type of construction shown in Fig. 4.
The puncture sealant abillty and resistance to ~ - flow of the composition of the invention may be tested .~ in an inflated tire. For this purpose the sealant is placed in the tire w~ich is run at 75 to 90 mph and !
a load sufficient to generate an internal temperature of 250F or higher. After running at hi~h speed the tire is then observed to determine whether the sealant ~ .
has flowed out of the shoulders of the tire and into the crown area or whether it has formed a puddle in the ~071785 -.14-bottom of the tlre after the tire was stopped. The ab~lity to resi~t flow at least 50 mph at an internal ; alr temperature of at least 200F is an important criterlon of performance for the present invention.
To evaluate puncture sealant ability, the tire is punctured with nalls of varlou9 sizes, which are subsequently removed from the tire, and the loss of air pressure wlthin the tire measured.~ Another impo~n~ ad~ant~ge of the present invention is the ablllty o~ the sealant compo~ition to seal holes of at least 0.125 inche in diameter.
The following example will serve to 111ustrate the practice of the inventlon in more detail.
1 ~80 grams of natural rubber (Standard Malaysian - 15 Rubber, Mooney viscosity 64 ML-4-212F., weight average ~
; molecular weight 4.7 x 10 ) was dissolved in 4 gallons r of n-hexane. To this solution was added 960 grams o~ depolymerized natural rubber (DPR-400 [trademark], ~- Hardman Company, viscosity 80,000 cps~150F.) and the~mixture stirred until it is uniform. 100.8 grams of tetra-n-butyl titanate was added and the cement .
~;~ stirred once more. 24 grams of Antioxidant 2246 [trade-mark, American Cyanamid, 2,2'-methylene-bis(4-methyl-
6-tert-butylphenol)] was added at this point. The re-; 25 sulting cement had a solids content of about 14%.
The cement was then coated onto the inside air-retaining liner of a HR 78-15 radial tire for a distance of 4 inches on either side of the center point up the inner side walls of the tire. The liner had first been 30 cleaned by washing with soap and water, and then dried.
107~785 .
me cement was laid down by painting thin æuccessive layers until a weight of 1200 grams of dry solids was reached around the complete circumference of the tire.
The solvent was allowed to evaporate overnight at room temperature and cure was completed by allowing the tire to sit at room temperature for 5 days. This process can be accelerated so that an equivalent cure can be attained by heating the tire ~or 24 hours at 200F. After cure the gel content of the sealant composition was 35% as mea-sured in toluene at room temperature compared to about 5% before cure.
The modified tire was tested by mounting it on l a standard automobile rim, inflating it to 28 psi and : running it on a Getty sheel, ll-inch diameter, for one hour at 50 miles per hour in orderb~therma~y equilibrate the tire. Eight 20-penny nails (about 0.185 inch shank diameter) were then driven into each of the 6 grooves of the tire tread, from edge to edge, one through each groove and two others between lugs, so that the head of the nail could not be driven flush into the groove through a rib. The tire was then run an additional 20 hours at 50 miles per hour without an adjustment of the inflation pressure. During this period, there was little or no loss of àir from the tire. All the nails were then removed and it was observed that there were holes ~ in the tread of about the same diameter as the shanks :! of the nails. Most importantly, it was observed that durlng the removal and immediately thereafter, there was only a slight loss of inflation pressure (less 30 than 4 psi) followed by complete sealing of all holes :` :
by the puncture sealant. The tire was then run an additional 10,000 miles (200 hours at 50 mph) during which period no further loss in inflation pressure was observed.
A similar tire containing no puncture sealant coating S lost complete inflation pressure when subjected to the foregoing test, immediately after removal of the nails.
A tire, in which the sealant, comprising 60% DPR-400 and 40% natural rubber, was applied by extrusion at 250F. as a 0.100 inch layer to the inner liner of the tire, gave a result 10 similar to the tire in which the sealant was applied from a ~
solution. For extrusion, a mixture of 6 lbs of DPR-400, 45 gms. --Antioxidant 2246 and 6 lbs. of creamed Hevea natural rubber latex (67% total solids) were mixed in a double-arm sigma blade dough mixer at a shell temp. of 270F. for 30 minutes. Vacuum ` 15 was then applied and mixing continued for 30 minutes at which time the moisture content of the blend was less than 0.2%. The mixture was cooled to about 170F and 272 gms. of tetra-n-butyl titanate was added. The mixer was tightly closed and mixing continued for an additionàl 30 minutes. The resultant `~ 20 composition was then extruded at 250F. as a 0.10 inch layer to the inner liner of a tire. The initial Mooney viscosity at ` room temperature (large rotor, ~L) of the fully cured sealant was 55.
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~07~785 The cure (crosslinking ox gelling to an insoluble state) of unsaturated eIastomer with an organo titanate ester takes place only when the mixture is exposed to the open atmosphere and can be prevented by maintaining the mixture in a closed system. The unsaturated elastomers that may be cured with titanate ester include cis-polyisoprene (whether natural or synthetic), polybutadiene, notably cis-polybutadiene, butadiene-styrene copolymer rubber, butadiene-acrylonitrile copolymer rubber, EPDM rubber (notably ethylene-propylene-5-10 ethylidene-2-norbornene terpolymer rubber having an iodine ;
; number greater than 8), polychloroprene rubber, butyl rubber (isoprene-isobutylene copolymer), and blends of such elastomers.
The organo titanate esters employed as curatives or crosslinking ~ agents to gel the unsaturated elastomer are tetrahydrocarbyl .-,~ titanates of the formula (Ro)4Ti where R is hydrocarbyl group, $ such as an alkyl group, e.g., an alkyl group having 1 to 12 q carbon atoms, preferably 3 to 8 carbon atoms, or an aryl group .:j .~ having 6 to 10 carbon atoms, such as cresyl. In preparing the curable composition the mixing of the organo titanate ester 20 crosslinking agent and unsaturated elastomer may be carried out -~ under non-evaporative conditions in a closed system such as an internal mixer, e.g., a sigma blade mixer (such as a Baker-Perkins [trademark3 or a closed Brebender mixer [trademark]).
i Alternatively, the organo titanate ester may be mixed with the unsaturated elastomer in solution in an inert volatile organic solvent for the elastomer (e.g., n-hexane), ~071785 -18- :
preferably ln the presence of a small amount of volatile alcohol (e.g., ethyl alcohol) to suppress premature gellatlnn. Gellatlon then occurs only after evaporation of the solvent and alcohol. In the most typlcal practlce the mixing is carried ou* under con-ditions whlch suppress gellation (i.e., in a closed system under non-evaporative conditions, or in the presence of a volatile alcohol) and then, after the mixture has been shaped into the desired form (e.g , .' 1 ' j 10 ~ molded, extruded, coated, etc.), the mixture is permltted j - . ~ ~ .
` to gel simply by exposing to evaporative conditlons ln the open atmosphere. Depending on the rubber and the amount of extraneous hydroxyllc compounds such as anti-~;i; oxldants (hydroxylic compounds are inhlbitlng substances i~, 15 in the cure) it contains, the amount and type o~ titanate ,,itl ester used dictate the rate and extent of cure obtalned.
,:1 The temperature and tlme requlred for titan~te cure again depend on the presence or absence of hydroxy-:!.
~ lic (inhibiting) additives and the type and level of tita-1~
nate employed. Cure of the mixture is accompanied by ~j; evaporatlon of alcohol, corresponding to the alkoxy portion of the titanate ester. Hence, titanate esters of lower boiling alcohols effect cure more rapidly than titanate esters of higher boillng alcohols, e.~., iso-propyl titanate acts more rapidly than butyl titanate which ln turn~t~ more rapidly than ethylhexyl tltanate.
Elevated temperatures speed up the cure rate regardless of the type and level of titanate, although in the absence o~ added hydroxylic inhibitor and solvent cure is rapid at room temperature. In general, from 1 to 10 days are 1~7~785 ~ , , - 19 - f required for cure at room temperature depending on such factors as the nature o~ the rubber~ the amo~nt o~
hydroxylic impurlty, the surface to volume ratio (the greater the surface exposed, the more rapid the cure), as~well as the level and type of titanate ester. It is ; ` a remarkable feature of the cure that the curable mixture can ~e processed at elevated temperatures (under non-evaporative conditions) without premature cure, and yet cure can be accomplished at ambient temperature (under 1 10 evaporatlve conditlons). ~ -'1~ , .
As indica~ed, it has been observed that the titan~te curing reaction ie accompanied by the evolution i o~ alcohol, that is, an alcohol ROH correspondlng to the organic group of the ester (RO)4Ti 1B generated dur-ing the cure. If the alcohol is prevented from evaporat-~1 ing, as ln a closed contalner where non-evaporative condi-tlons prevail, the cure will not go forward. However, ,, when the curable composition is placed in the open atmosphere where evaporative conditions prevail, and ;` 20 the evolved alcohol ROH can escape, the cure proceeds.
Thln sectlons such as coatings deposlted ~rom a solu-;~ tion, calendered or ex*ruded films and sheets, and slmilar thin sections (e.g., 0.2 inch thick or less) have higher surface to volume ratio than thicker sections (such as most molded ob~ects) and present greater oppor-tunlty for the generated alcohol ROH to escape. There-` fore such thin sections cure more rapidly than thick sections.
As the titanate cure proceeds the gel content of the rubber (that is, the fraction insoluble in , ' org~nic liquids that are normally solvents for the un-; cured elastomer) increases, lndicatlng that crossllnklng is taklng place, and evolutlon of alcohol continues un-til a plateau of gel content is reached. `~ *
As indicated, hydroxyllc additives have an in-hiblting effect on the titanate cure. For instance phenolic antloxldants have been found to slow down the cure rate. When such antioxidants are removed as nearly ;3 as possible solutions of the rubbers tend to gel qulckly whén titanate esters are added. Normally, appreciable gellation occurs slowly upon evaporation o~ solvent from ~, .
the solution. Addition of small amounts of volatile - alcohol to solutions of rubber inhlbits any tendency to-ward premature gellation. In fact, the rate of cure can `i 15 be controlled by the molecular weight of the added al-., ` cohol. Low molecular weight alcohols such as ethyl al-cohol have a mild or temporary lnhibiting effect while higher boiling aIcohols such as dodecyl a~cohol have a more severe and lasting inhibiting effect. After gellation, the gelled rubber is insoluble to toluene :, , - and other organic 501vents, but addition of acid sUCh as acetlc acid reverses the process and the rubber be-comes soluble again. Addition of carboxylic acids like-wise inhibits gel formation. It appears to be possible that the crosslinking is a consequence of titanate ester formation with the elastomer.
- Preferred elastomers for use with the titanate cure are those selected from the group consisting of natural rubber, synthetic cis-polyisoprene elastomer, cis-polybutadiene elastomer and ethylene-propylene-5-~071785 -: -21- -ethylidene-2-norbornene terpolymer rubber having an iodine number of at least 12, in low molecular weight (liquid) or high molecular weight (solid) form, It will be understood that the measurements of gel content and Mooney viscosity set forth above ; for the flnal cured puncture sealant layer are obtain-.' able on a separate sample of the sealant composition which has been sub~ected to curing conditions sub-stant1ally equivalent to those to which the final seal-. ant layer is sub~ected; it is of course not practucal :~~ to make these measurements on an actual layer in the tire itsel~.
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:
, ~071785 SUPPLEMENTARY DISCLOSURE
In a preferred form of the invention the puncture sealing mixture contains one or more tackifying or plasticizing substances which may allow a reduction in the amount of low molecular weight elastomer, but the total of tackifying or plasticizing substance plus low molecular weight elastomer is - more than 50~ of the mixture. Substitution of such a tackifying or plasticizing substance for a portion of the low molecular weight elastomer enhances the adhesion and conformability of the resultant composition.
A frequently preferred low molecular weight elastomer --is a "liquid" type rubber with a maximum Brookfield viscosity at 150F of 2,000,000 cps., ordinarily within the range of from 20,000 to l,OOO,OOO cps.
The tackifying or plasticizing substances which are preferably included in the composition are low molecular weight materials such as rosin esters (e.g.,staybelite [trademark]
Ester 10~; aliphatic petroleum hydrocarbon resins (e.g., Piccopale [trademark] A-70); polyterpene resins derived from alpha-pinene (e.g., Piccolyte [trademark] A-10), beta-pinene (e.g., Piccolyte [trademark] S-25); resins made from styrene and related monomers (e.g., Piccolastic [trademark] A-5); resins made from dicyclopentadiene (e.g., Piccodiene [trademark] 2215);
and resins from the reaction of a mineral oil purification residue with formaldehyde and the nitric acid catalyst according to U. S. Patent 3,544,494, Schmidt et al., December 1, 1970, sold under the tradename of Struktol ~trademark].
107~785 - The sealant composition of the invention contains a major proportion, that is, between more than 50% and 90~ by weight of total low molecular weight material (i.e., low molecular weight elastomer plus low molecular weight tackifier) based on the weight of the two elastomers plus - tackifier or plasticizer. The amount of tackifier or plasti-cizer is usually preferably at least 10% and may range up to .,:
` 70% for example, based on the weight of low molecular weight -elastomer plus tackifier or plasticizer. The ratio of high to low molecular weight components depends ma~nly on the molecular weight of the high molecular ~eight elastomer and other variables such as the particular elastomer involved, the amount and kind of crosslinking agent, and the conditions of the cros~inking treatment. The proportiongof the two elastomeric components are preferably chosen so as to give a p~ak Mooney viscosity at 150F (the maximum reading attained, which is usually at about 90 seconds of the 4 minute Moone~
curve) of between 30 and 55 (large rotor, ML) in the final crosslinked mixture, with a pre~erred range ~f 40 to 50.
``!
EXAMPLE III
A æealant containing equal parts of natural rubber, DPR-400 and Struktol 30, along with 8% tetraisopropyl ti-;; tanate and 1% ~ntioxidant 2246 (both based on total rubber) was mixed according to the procedure of the second sample.
It was then extruded onto the liner of a tire as a 0.125"
layer at 240F and cured by heating for 7 days at 150F.
ma ML peak of the cured sealant at 150~ was 35 and its gel content was 33,1~ measured in toluene at 50C for 24 hours.
me tire was mounted on a rim and in~lated. As a measure of sealing efficiency, four 20d nails, 2-1/2'l ~. .
, , long were dri~en into the tire3 one in the outer rib, one ~n the outer groove and two in inner positions. The tire was then run on the Getty wheel, starting at 50 mph, for one hour periods at speed increments of 5 mph, until all ; 5 the na~l were ejected ~rom the tire. All the holes, which i~ in this test were the same diameter as the shank of the nail, sealed and no inflation was lost. A tire containing no sealant went flat within 1 minute after the first nail was ejected in this test.
EXAMPLE IV
. ~ . .
A sealant identical to that of Example III, except that it contained 10% tetra-isopropyl titanate (based on the total rubber) was extruded into each o~
four tires as a 0.125" strip and cured as above. The cured sealant had ~ eak v~lues at 150F ranging from 35 to 45 and gel contents of 18 to 25~. The tires were then mounted on a car, each with a 20d nall dri~en into I an outside or inside tread position, and the car driven i ~n 100 milecycl~s at the following speeds, until the nails were e~ected.
22.5 miles at 30 mph 37.5 miles at 50 mph 40 miles at 80 mph For each tire, when the nail was ejected the hole sealed with little or no loss of inflation and the car was able to contir.ue running. Uncoated tires, when tested simil-arly, lost inflation rapidly and went flat within one minute.
-2~-.
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EXAMPLE V
A sealant containing 50 parts of natural rubber, 50 parts of DPR-400 and 70 parts of Piccadiene 2215 (a tackifying i~
~ resin made from polymerized dicyclopentadiene, manufactured by Hercules, Inc), plus 8% tetra-isopropyl titanate and 10~ Anti-oxidant 2246 (based on total rubber) was mixed according to the procedure of the second example. It was then extruded at 250F. as a 0.125" thick strip into a tire and cured. The puncture sealing efficiency of this material measured in the nail ejection test of Example III, showed an average sealing efficiency of 75~ (3 out of 4 nail holes sealed).
EXAMPLE VI
A sealant composition containing 50 parts each of natural rubber and DPR-400, plus 50 parts of Piccopale 100 (a hydrocarbon polymer tackifying resin, Hercules, Inc.), 16%
tetra-isopropyl titanate and 10% Antioxidant 2246 (based on the total rubber) was mixed and extruded into a tire at 250F. as ~;~
a 0.125" strip. Its sealing efficiency in the nail ejection test of Example III was greater than 75%.
EXAMPLE VII
A sealant mixture of 50 parts by weight each of natural rubber, DPR-400 and Struktol 30, plus 10 parts by weight of Antioxidant 2246 was extruded at 250~F. as a flat strip, 0.250" thick and 8" wide. It was then irradiated in a 1.4 million volt electron beam at a dosage of 20 megarads. The irradiated sample showed a gel content of 29.6% and an MLpeak at 150F. of 35. The strip was then incorporated ~071785 , -26-on top o~ the llner in an uncured steel-belted radial tire which was cured in a convent~onal tire press.
The tire ga~-e 100% sealing efficiency in the nail e~ection test of EY.ample III.
E~UU~PLE VIII
- A sealant co~nposition containing 40 parts by weight of natural rubber, 30 parts by weight of DPR-400 and 30 parts by weight of Struktol 30, along with 4.2 parts by weight of tetra-isopropyl titanate and 0.7 parts by weight o~ Antioxidant 2246 was mixed accord-ing to the procedure of the second example. It was then extruded into a tire at 240F. as a 0.125" strip, ; cured and tested in the nail e~ection test of Example Ill.
Its average sealing efficiency was 70%.
E~U~PLæ IX
: -Two parts of Butyl ~M 430 (Enjay liquid polyisobutylene, viscosity a~erage molecular weight 32,000, about 4 mole percent unsaturation) and one part-EPDM (Uniroyal, Inc., ethylene-propylene-ethylidene norbornene terpolymer, 58/42 ethylene-propylene ratio, iodine number 20, ML-4=50 at 257F.) were dissolved in hexane to yield a concentration of about 10%. 8 phr (based on the total rubber content) o~ tetra-n-butyl titanate was added and the mixture painted into the inside o~ a tire in an 8 inch width.
Sufficient solution was used to leave a layer 0.125"
in thickness when the solvent had completely evaporated.
The sealant ~as allowed to cure by storage ~or at least 24 hours at room te~perature a~ter complete removal .
-26_ 107i785 of sol~ent. The tire was inflated on a rlm and then punctured in the tread wlth fou~ nails o~ 0.125"
diamcter. l'he tire was then run 1000 miles at 50 mph ! on a Getty wheel and the nails then remo~ed. There was less than 4 psi loss of inflation and the holes ~ all sealed.
,~ EXAMPIE X
J' A sealant composition containing equal parts of Butyl ~M ~30, ~PDM and Piccolyte A100 (a polyterpene resin derived from alpha-pinene, soften-ing point 100C.), plus 6% tetra-n-butyl titanate (based on total rubber) was made up in hexane solution an~ painted into a tire to yield a str~p 8" wide and 0.125" thick after e~aporation. After curing at room temperature, the sealing efficiency of the coat-ing was tested in the same manner as in Example IX, using 0.125" nails. Complete sealing after the nails were remo~ed, with little or no loss of inflation, was $ound.
EX~IPLE XI
A sealant composition containing equal parts of EPDM, Butyl LM 430 and Piccodiene 2215, plus 10% tetra-n-butyl titanate (based on total rubber) was dissolved in hexane and painted into a tire to yield a strip 8" wide and 0.125" thick after evaporation. After being allowed to cure at room temperature, the tire was tested for sealing effi-ciency as in Exa~ple Y. T~YO nails of 0.125 diameter were used and when removed after 1000 ~niles, there was no loss of inflation.
. -,~
AMPIE XII
A sealant composltion containing equal parts of EPDM (ethylene-propylene-ethylidene norbornene terpolymer, iodine number 20, ML-4=55 at 257F.~, Bu~yl LM 430, and Struktol 30, plus 10% tetra~iso-propyl titanate (based on the total rubber content) was dissolved ~n nexane and painted into a tire to - yield a strip 8" wide and 0.125" thick when evaporated.
The sealant was allowed to cure at room temperature, after ~hich the tire was mounted on a rim and lnflated to 28 psi. It was then punctured with two 20d nails and run at 50 mph for 20 hours. me nails were then pulled out with no loss of inflation being noted.
EXAMPLE XIII
A sealant containing 57 parts natural rubber, ;1 43 parts DPR-400, 43 parts Struktol 30 and 21 parts i Piccopale 100, plus 1% Antloxidant 22~6 and 2.g~
tetra-isopropyl titanate (both based on total rub-ber) was mixed according to the procedure of Example II. It was then extruded at 240F. as a 0.125" strip, 8" wide, into a tire and cured. The puncture sealing ef~ic~ency of this material measured in the nail ejec-tlon test described in Example III, wes 75%.
:, .
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The cement was then coated onto the inside air-retaining liner of a HR 78-15 radial tire for a distance of 4 inches on either side of the center point up the inner side walls of the tire. The liner had first been 30 cleaned by washing with soap and water, and then dried.
107~785 .
me cement was laid down by painting thin æuccessive layers until a weight of 1200 grams of dry solids was reached around the complete circumference of the tire.
The solvent was allowed to evaporate overnight at room temperature and cure was completed by allowing the tire to sit at room temperature for 5 days. This process can be accelerated so that an equivalent cure can be attained by heating the tire ~or 24 hours at 200F. After cure the gel content of the sealant composition was 35% as mea-sured in toluene at room temperature compared to about 5% before cure.
The modified tire was tested by mounting it on l a standard automobile rim, inflating it to 28 psi and : running it on a Getty sheel, ll-inch diameter, for one hour at 50 miles per hour in orderb~therma~y equilibrate the tire. Eight 20-penny nails (about 0.185 inch shank diameter) were then driven into each of the 6 grooves of the tire tread, from edge to edge, one through each groove and two others between lugs, so that the head of the nail could not be driven flush into the groove through a rib. The tire was then run an additional 20 hours at 50 miles per hour without an adjustment of the inflation pressure. During this period, there was little or no loss of àir from the tire. All the nails were then removed and it was observed that there were holes ~ in the tread of about the same diameter as the shanks :! of the nails. Most importantly, it was observed that durlng the removal and immediately thereafter, there was only a slight loss of inflation pressure (less 30 than 4 psi) followed by complete sealing of all holes :` :
by the puncture sealant. The tire was then run an additional 10,000 miles (200 hours at 50 mph) during which period no further loss in inflation pressure was observed.
A similar tire containing no puncture sealant coating S lost complete inflation pressure when subjected to the foregoing test, immediately after removal of the nails.
A tire, in which the sealant, comprising 60% DPR-400 and 40% natural rubber, was applied by extrusion at 250F. as a 0.100 inch layer to the inner liner of the tire, gave a result 10 similar to the tire in which the sealant was applied from a ~
solution. For extrusion, a mixture of 6 lbs of DPR-400, 45 gms. --Antioxidant 2246 and 6 lbs. of creamed Hevea natural rubber latex (67% total solids) were mixed in a double-arm sigma blade dough mixer at a shell temp. of 270F. for 30 minutes. Vacuum ` 15 was then applied and mixing continued for 30 minutes at which time the moisture content of the blend was less than 0.2%. The mixture was cooled to about 170F and 272 gms. of tetra-n-butyl titanate was added. The mixer was tightly closed and mixing continued for an additionàl 30 minutes. The resultant `~ 20 composition was then extruded at 250F. as a 0.10 inch layer to the inner liner of a tire. The initial Mooney viscosity at ` room temperature (large rotor, ~L) of the fully cured sealant was 55.
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~07~785 The cure (crosslinking ox gelling to an insoluble state) of unsaturated eIastomer with an organo titanate ester takes place only when the mixture is exposed to the open atmosphere and can be prevented by maintaining the mixture in a closed system. The unsaturated elastomers that may be cured with titanate ester include cis-polyisoprene (whether natural or synthetic), polybutadiene, notably cis-polybutadiene, butadiene-styrene copolymer rubber, butadiene-acrylonitrile copolymer rubber, EPDM rubber (notably ethylene-propylene-5-10 ethylidene-2-norbornene terpolymer rubber having an iodine ;
; number greater than 8), polychloroprene rubber, butyl rubber (isoprene-isobutylene copolymer), and blends of such elastomers.
The organo titanate esters employed as curatives or crosslinking ~ agents to gel the unsaturated elastomer are tetrahydrocarbyl .-,~ titanates of the formula (Ro)4Ti where R is hydrocarbyl group, $ such as an alkyl group, e.g., an alkyl group having 1 to 12 q carbon atoms, preferably 3 to 8 carbon atoms, or an aryl group .:j .~ having 6 to 10 carbon atoms, such as cresyl. In preparing the curable composition the mixing of the organo titanate ester 20 crosslinking agent and unsaturated elastomer may be carried out -~ under non-evaporative conditions in a closed system such as an internal mixer, e.g., a sigma blade mixer (such as a Baker-Perkins [trademark3 or a closed Brebender mixer [trademark]).
i Alternatively, the organo titanate ester may be mixed with the unsaturated elastomer in solution in an inert volatile organic solvent for the elastomer (e.g., n-hexane), ~071785 -18- :
preferably ln the presence of a small amount of volatile alcohol (e.g., ethyl alcohol) to suppress premature gellatlnn. Gellatlon then occurs only after evaporation of the solvent and alcohol. In the most typlcal practlce the mixing is carried ou* under con-ditions whlch suppress gellation (i.e., in a closed system under non-evaporative conditions, or in the presence of a volatile alcohol) and then, after the mixture has been shaped into the desired form (e.g , .' 1 ' j 10 ~ molded, extruded, coated, etc.), the mixture is permltted j - . ~ ~ .
` to gel simply by exposing to evaporative conditlons ln the open atmosphere. Depending on the rubber and the amount of extraneous hydroxyllc compounds such as anti-~;i; oxldants (hydroxylic compounds are inhlbitlng substances i~, 15 in the cure) it contains, the amount and type o~ titanate ,,itl ester used dictate the rate and extent of cure obtalned.
,:1 The temperature and tlme requlred for titan~te cure again depend on the presence or absence of hydroxy-:!.
~ lic (inhibiting) additives and the type and level of tita-1~
nate employed. Cure of the mixture is accompanied by ~j; evaporatlon of alcohol, corresponding to the alkoxy portion of the titanate ester. Hence, titanate esters of lower boiling alcohols effect cure more rapidly than titanate esters of higher boillng alcohols, e.~., iso-propyl titanate acts more rapidly than butyl titanate which ln turn~t~ more rapidly than ethylhexyl tltanate.
Elevated temperatures speed up the cure rate regardless of the type and level of titanate, although in the absence o~ added hydroxylic inhibitor and solvent cure is rapid at room temperature. In general, from 1 to 10 days are 1~7~785 ~ , , - 19 - f required for cure at room temperature depending on such factors as the nature o~ the rubber~ the amo~nt o~
hydroxylic impurlty, the surface to volume ratio (the greater the surface exposed, the more rapid the cure), as~well as the level and type of titanate ester. It is ; ` a remarkable feature of the cure that the curable mixture can ~e processed at elevated temperatures (under non-evaporative conditions) without premature cure, and yet cure can be accomplished at ambient temperature (under 1 10 evaporatlve conditlons). ~ -'1~ , .
As indica~ed, it has been observed that the titan~te curing reaction ie accompanied by the evolution i o~ alcohol, that is, an alcohol ROH correspondlng to the organic group of the ester (RO)4Ti 1B generated dur-ing the cure. If the alcohol is prevented from evaporat-~1 ing, as ln a closed contalner where non-evaporative condi-tlons prevail, the cure will not go forward. However, ,, when the curable composition is placed in the open atmosphere where evaporative conditions prevail, and ;` 20 the evolved alcohol ROH can escape, the cure proceeds.
Thln sectlons such as coatings deposlted ~rom a solu-;~ tion, calendered or ex*ruded films and sheets, and slmilar thin sections (e.g., 0.2 inch thick or less) have higher surface to volume ratio than thicker sections (such as most molded ob~ects) and present greater oppor-tunlty for the generated alcohol ROH to escape. There-` fore such thin sections cure more rapidly than thick sections.
As the titanate cure proceeds the gel content of the rubber (that is, the fraction insoluble in , ' org~nic liquids that are normally solvents for the un-; cured elastomer) increases, lndicatlng that crossllnklng is taklng place, and evolutlon of alcohol continues un-til a plateau of gel content is reached. `~ *
As indicated, hydroxyllc additives have an in-hiblting effect on the titanate cure. For instance phenolic antloxldants have been found to slow down the cure rate. When such antioxidants are removed as nearly ;3 as possible solutions of the rubbers tend to gel qulckly whén titanate esters are added. Normally, appreciable gellation occurs slowly upon evaporation o~ solvent from ~, .
the solution. Addition of small amounts of volatile - alcohol to solutions of rubber inhlbits any tendency to-ward premature gellation. In fact, the rate of cure can `i 15 be controlled by the molecular weight of the added al-., ` cohol. Low molecular weight alcohols such as ethyl al-cohol have a mild or temporary lnhibiting effect while higher boiling aIcohols such as dodecyl a~cohol have a more severe and lasting inhibiting effect. After gellation, the gelled rubber is insoluble to toluene :, , - and other organic 501vents, but addition of acid sUCh as acetlc acid reverses the process and the rubber be-comes soluble again. Addition of carboxylic acids like-wise inhibits gel formation. It appears to be possible that the crosslinking is a consequence of titanate ester formation with the elastomer.
- Preferred elastomers for use with the titanate cure are those selected from the group consisting of natural rubber, synthetic cis-polyisoprene elastomer, cis-polybutadiene elastomer and ethylene-propylene-5-~071785 -: -21- -ethylidene-2-norbornene terpolymer rubber having an iodine number of at least 12, in low molecular weight (liquid) or high molecular weight (solid) form, It will be understood that the measurements of gel content and Mooney viscosity set forth above ; for the flnal cured puncture sealant layer are obtain-.' able on a separate sample of the sealant composition which has been sub~ected to curing conditions sub-stant1ally equivalent to those to which the final seal-. ant layer is sub~ected; it is of course not practucal :~~ to make these measurements on an actual layer in the tire itsel~.
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, ~071785 SUPPLEMENTARY DISCLOSURE
In a preferred form of the invention the puncture sealing mixture contains one or more tackifying or plasticizing substances which may allow a reduction in the amount of low molecular weight elastomer, but the total of tackifying or plasticizing substance plus low molecular weight elastomer is - more than 50~ of the mixture. Substitution of such a tackifying or plasticizing substance for a portion of the low molecular weight elastomer enhances the adhesion and conformability of the resultant composition.
A frequently preferred low molecular weight elastomer --is a "liquid" type rubber with a maximum Brookfield viscosity at 150F of 2,000,000 cps., ordinarily within the range of from 20,000 to l,OOO,OOO cps.
The tackifying or plasticizing substances which are preferably included in the composition are low molecular weight materials such as rosin esters (e.g.,staybelite [trademark]
Ester 10~; aliphatic petroleum hydrocarbon resins (e.g., Piccopale [trademark] A-70); polyterpene resins derived from alpha-pinene (e.g., Piccolyte [trademark] A-10), beta-pinene (e.g., Piccolyte [trademark] S-25); resins made from styrene and related monomers (e.g., Piccolastic [trademark] A-5); resins made from dicyclopentadiene (e.g., Piccodiene [trademark] 2215);
and resins from the reaction of a mineral oil purification residue with formaldehyde and the nitric acid catalyst according to U. S. Patent 3,544,494, Schmidt et al., December 1, 1970, sold under the tradename of Struktol ~trademark].
107~785 - The sealant composition of the invention contains a major proportion, that is, between more than 50% and 90~ by weight of total low molecular weight material (i.e., low molecular weight elastomer plus low molecular weight tackifier) based on the weight of the two elastomers plus - tackifier or plasticizer. The amount of tackifier or plasti-cizer is usually preferably at least 10% and may range up to .,:
` 70% for example, based on the weight of low molecular weight -elastomer plus tackifier or plasticizer. The ratio of high to low molecular weight components depends ma~nly on the molecular weight of the high molecular ~eight elastomer and other variables such as the particular elastomer involved, the amount and kind of crosslinking agent, and the conditions of the cros~inking treatment. The proportiongof the two elastomeric components are preferably chosen so as to give a p~ak Mooney viscosity at 150F (the maximum reading attained, which is usually at about 90 seconds of the 4 minute Moone~
curve) of between 30 and 55 (large rotor, ML) in the final crosslinked mixture, with a pre~erred range ~f 40 to 50.
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EXAMPLE III
A æealant containing equal parts of natural rubber, DPR-400 and Struktol 30, along with 8% tetraisopropyl ti-;; tanate and 1% ~ntioxidant 2246 (both based on total rubber) was mixed according to the procedure of the second sample.
It was then extruded onto the liner of a tire as a 0.125"
layer at 240F and cured by heating for 7 days at 150F.
ma ML peak of the cured sealant at 150~ was 35 and its gel content was 33,1~ measured in toluene at 50C for 24 hours.
me tire was mounted on a rim and in~lated. As a measure of sealing efficiency, four 20d nails, 2-1/2'l ~. .
, , long were dri~en into the tire3 one in the outer rib, one ~n the outer groove and two in inner positions. The tire was then run on the Getty wheel, starting at 50 mph, for one hour periods at speed increments of 5 mph, until all ; 5 the na~l were ejected ~rom the tire. All the holes, which i~ in this test were the same diameter as the shank of the nail, sealed and no inflation was lost. A tire containing no sealant went flat within 1 minute after the first nail was ejected in this test.
EXAMPLE IV
. ~ . .
A sealant identical to that of Example III, except that it contained 10% tetra-isopropyl titanate (based on the total rubber) was extruded into each o~
four tires as a 0.125" strip and cured as above. The cured sealant had ~ eak v~lues at 150F ranging from 35 to 45 and gel contents of 18 to 25~. The tires were then mounted on a car, each with a 20d nall dri~en into I an outside or inside tread position, and the car driven i ~n 100 milecycl~s at the following speeds, until the nails were e~ected.
22.5 miles at 30 mph 37.5 miles at 50 mph 40 miles at 80 mph For each tire, when the nail was ejected the hole sealed with little or no loss of inflation and the car was able to contir.ue running. Uncoated tires, when tested simil-arly, lost inflation rapidly and went flat within one minute.
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EXAMPLE V
A sealant containing 50 parts of natural rubber, 50 parts of DPR-400 and 70 parts of Piccadiene 2215 (a tackifying i~
~ resin made from polymerized dicyclopentadiene, manufactured by Hercules, Inc), plus 8% tetra-isopropyl titanate and 10~ Anti-oxidant 2246 (based on total rubber) was mixed according to the procedure of the second example. It was then extruded at 250F. as a 0.125" thick strip into a tire and cured. The puncture sealing efficiency of this material measured in the nail ejection test of Example III, showed an average sealing efficiency of 75~ (3 out of 4 nail holes sealed).
EXAMPLE VI
A sealant composition containing 50 parts each of natural rubber and DPR-400, plus 50 parts of Piccopale 100 (a hydrocarbon polymer tackifying resin, Hercules, Inc.), 16%
tetra-isopropyl titanate and 10% Antioxidant 2246 (based on the total rubber) was mixed and extruded into a tire at 250F. as ~;~
a 0.125" strip. Its sealing efficiency in the nail ejection test of Example III was greater than 75%.
EXAMPLE VII
A sealant mixture of 50 parts by weight each of natural rubber, DPR-400 and Struktol 30, plus 10 parts by weight of Antioxidant 2246 was extruded at 250~F. as a flat strip, 0.250" thick and 8" wide. It was then irradiated in a 1.4 million volt electron beam at a dosage of 20 megarads. The irradiated sample showed a gel content of 29.6% and an MLpeak at 150F. of 35. The strip was then incorporated ~071785 , -26-on top o~ the llner in an uncured steel-belted radial tire which was cured in a convent~onal tire press.
The tire ga~-e 100% sealing efficiency in the nail e~ection test of EY.ample III.
E~UU~PLE VIII
- A sealant co~nposition containing 40 parts by weight of natural rubber, 30 parts by weight of DPR-400 and 30 parts by weight of Struktol 30, along with 4.2 parts by weight of tetra-isopropyl titanate and 0.7 parts by weight o~ Antioxidant 2246 was mixed accord-ing to the procedure of the second example. It was then extruded into a tire at 240F. as a 0.125" strip, ; cured and tested in the nail e~ection test of Example Ill.
Its average sealing efficiency was 70%.
E~U~PLæ IX
: -Two parts of Butyl ~M 430 (Enjay liquid polyisobutylene, viscosity a~erage molecular weight 32,000, about 4 mole percent unsaturation) and one part-EPDM (Uniroyal, Inc., ethylene-propylene-ethylidene norbornene terpolymer, 58/42 ethylene-propylene ratio, iodine number 20, ML-4=50 at 257F.) were dissolved in hexane to yield a concentration of about 10%. 8 phr (based on the total rubber content) o~ tetra-n-butyl titanate was added and the mixture painted into the inside o~ a tire in an 8 inch width.
Sufficient solution was used to leave a layer 0.125"
in thickness when the solvent had completely evaporated.
The sealant ~as allowed to cure by storage ~or at least 24 hours at room te~perature a~ter complete removal .
-26_ 107i785 of sol~ent. The tire was inflated on a rlm and then punctured in the tread wlth fou~ nails o~ 0.125"
diamcter. l'he tire was then run 1000 miles at 50 mph ! on a Getty wheel and the nails then remo~ed. There was less than 4 psi loss of inflation and the holes ~ all sealed.
,~ EXAMPIE X
J' A sealant composition containing equal parts of Butyl ~M ~30, ~PDM and Piccolyte A100 (a polyterpene resin derived from alpha-pinene, soften-ing point 100C.), plus 6% tetra-n-butyl titanate (based on total rubber) was made up in hexane solution an~ painted into a tire to yield a str~p 8" wide and 0.125" thick after e~aporation. After curing at room temperature, the sealing efficiency of the coat-ing was tested in the same manner as in Example IX, using 0.125" nails. Complete sealing after the nails were remo~ed, with little or no loss of inflation, was $ound.
EX~IPLE XI
A sealant composition containing equal parts of EPDM, Butyl LM 430 and Piccodiene 2215, plus 10% tetra-n-butyl titanate (based on total rubber) was dissolved in hexane and painted into a tire to yield a strip 8" wide and 0.125" thick after evaporation. After being allowed to cure at room temperature, the tire was tested for sealing effi-ciency as in Exa~ple Y. T~YO nails of 0.125 diameter were used and when removed after 1000 ~niles, there was no loss of inflation.
. -,~
AMPIE XII
A sealant composltion containing equal parts of EPDM (ethylene-propylene-ethylidene norbornene terpolymer, iodine number 20, ML-4=55 at 257F.~, Bu~yl LM 430, and Struktol 30, plus 10% tetra~iso-propyl titanate (based on the total rubber content) was dissolved ~n nexane and painted into a tire to - yield a strip 8" wide and 0.125" thick when evaporated.
The sealant was allowed to cure at room temperature, after ~hich the tire was mounted on a rim and lnflated to 28 psi. It was then punctured with two 20d nails and run at 50 mph for 20 hours. me nails were then pulled out with no loss of inflation being noted.
EXAMPLE XIII
A sealant containing 57 parts natural rubber, ;1 43 parts DPR-400, 43 parts Struktol 30 and 21 parts i Piccopale 100, plus 1% Antloxidant 22~6 and 2.g~
tetra-isopropyl titanate (both based on total rub-ber) was mixed according to the procedure of Example II. It was then extruded at 240F. as a 0.125" strip, 8" wide, into a tire and cured. The puncture sealing ef~ic~ency of this material measured in the nail ejec-tlon test described in Example III, wes 75%.
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Claims (62)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A puncture sealing composition for a tubeless pneumatic tire comprising a fiber-free blend of a major propor-tion by weight of a low molecular weight liquid elastomer with a minor proportion by weight of a high molecular weight solid elastomer, and a crosslinking agent for the elastomers in amount effective to partially crosslink the elastomers to an extent sufficient to prevent the blend from flowing at elevated tempera-tures and centrifugal forces encountered in the tire in use, the blend having in the partially crosslinked state sufficient adhesion and conformability to function as a selant in the tire, the amount of said low molecular weight elastomer being from more than 50% to 90% by weight and the amount of said high molecular weight elastomer being correspondingly from less than 50% to 10% by weight, based on the combined weights of the two elastomers, the said low molecular weight elastomer being a liquid rubber having a Brookfield viscosity at 150°F of from 20,000 to 200,000 cps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, the said crosslinking agent being selected from the following, present in the amounts recited:
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative;
and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the par-tially crosslinked state being from 15 to 60% by weight of the blend as measured in toluene at room temperature and the initial Mooney viscosity of the blend being from 30 to 70 ML at room temperature.
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative;
and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the par-tially crosslinked state being from 15 to 60% by weight of the blend as measured in toluene at room temperature and the initial Mooney viscosity of the blend being from 30 to 70 ML at room temperature.
2. A puncture sealing composition as in claim 1 in which the liquid rubber is heat depolymerized natural rubber.
3. A puncture sealing composition as in claim 1 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid polybutadiene, liquid polybutene, liquid ethylene-propylene non-conjugated diene terpolymer rubber, and liquid isobutylene-isoprene copolymer rubber.
4. A puncture sealing composition as in claim 1 in which the high molecular weight elastomer is selected from the group consisting of conjugated diolefin homo-polymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copoly-mirizable able monoethylenically unsaturated monomer, copoly-mers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.
5. A puncture sealing composition as in claim 1 in which the low molecular weight elastomer is liquid heat depolymerized natural rubber and the high molecular weight elastomer is solid cis-polyisoprene rubber.
6. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of from more than 50% to 90%
by weight of a low molecular weight liquid elastomer which is liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F of from 20,000 to 200,000 cps with correspond-ingly from less than 50% to 10% by weight of a high molecular solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encount-ered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
by weight of a low molecular weight liquid elastomer which is liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F of from 20,000 to 200,000 cps with correspond-ingly from less than 50% to 10% by weight of a high molecular solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encount-ered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
7. A puncture sealing composition as in claim 6, devoid of fibrous filler, in which the said high molecular weight solid elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.
8. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of from more than 50% to 90%
by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps with correspondingly from less than 50% to 10% by weight of a high moelcular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conforma-bility to function as a sealant in the tire.
by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps with correspondingly from less than 50% to 10% by weight of a high moelcular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conforma-bility to function as a sealant in the tire.
9. A puncture sealing composition as in claim 8 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 3 to 8 parts per 100 parts by weight of the two elastomers, and the composition is devoid of fibrous filler.
10. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of from more than 50% to 90%
by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity of 150°F. of from 20,000 to 200,000 cps with correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., said blend being partially cross-linked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffi-cient adhesion and conformability to function as a sealant in the tire.
by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity of 150°F. of from 20,000 to 200,000 cps with correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., said blend being partially cross-linked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffi-cient adhesion and conformability to function as a sealant in the tire.
11. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of from more than 50% to 90%
by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps.
with correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps.
with correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
12. A puncture sealing composition as in claim 11 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetraalkyl titanate crosslinking agent is from 3 to 8 parts per 100 parts by weight of the two elastomers.
13. A puncture sealing composition as in claim 12 in which the tetraalkyl titanate ester crosslinking agent is tetra-n-butyl titanate.
14. A puncture sealing tubeless-pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a fiber-free blend of a major proportion by weight of a low molecular weight liquid elastomer with a minor proportion by weight of a high molecular weight solid elastomer, partially crosslinked at an extent sufficient to prevent the blend from flowing at elevated temperatures and centrifugal forces encountered in the tire in use, the partially crosslinked blend having sufficient adhesion and conformability to function as a sealant in the tire, the amount of said low molecular weight elastomer being from more than 50% to 90% by weight and the amount of said high molecular weight elastomer being correspondingly from less than 50% to 10% by weight, based on the combined weights of the two elastomers, the said low molecular weight elastomer being a liquid rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., the said composition containing a crosslinking agent selected from the following, present in the amounts recited:
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 parts of radical generating curative;
from 2 to 10 parts of polyisocyanate curative; and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in toluene at room temperature, and the initial Mooney viscosity of the blend in the partially crosslinked state being from 30 to 70 ML at room temperature.
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 parts of radical generating curative;
from 2 to 10 parts of polyisocyanate curative; and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in toluene at room temperature, and the initial Mooney viscosity of the blend in the partially crosslinked state being from 30 to 70 ML at room temperature.
15. A tire as in claim 14 in which the said puncture sealing layer is disposed on the inside surface of the said liner.
16. A tire as in claim 14 in which the said sealing layer is sandwiched between the liner and the inside surface of the carcass.
17. A tire as in claim 14 in which the liquid rubber is heat depolymerized natural rubber.
18. A tire as in claim 14 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid polybutadiene, liquid polybutene, liquid ethylene-propylene-non-conjugated diene terpolymer rubber, and liquid isobutyleneisoprene copolymer rubber.
19. A tire as in claim 14 in which the high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethene-propylene-non-conjugated diene terpolymers, and saturated elastomers.
20. A tire as in claim 14 in which the low molecular weight elastomer is liquid heat depolymerized natural rubber and the high molecular weight elastomer is solid cis-polyisoprene rubber.
21. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of from more than 50% to 90% by weight of a low molecular weight liquid elastomer which is liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps with correspondingly from less than 50% to 10% by weight of a high molecular solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F. said blend being partially cross-linked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffi-cient adhesion and conformability to function as a sealant in the tire.
22. A tire as in claim 21, in which the said blend is devoid of fibrous filler, and in which the said high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.
23. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of from more than 50% to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity of 150°F. of from 20,000 to 200,000 cps. with correspondingly from less than 50%
to 10% by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 4 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50%
by weight based on the weight of the blend as measured in toluene at room temperatures and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffi-cient adhesion and conformability to function as a sealant in the tire.
to 10% by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 4 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50%
by weight based on the weight of the blend as measured in toluene at room temperatures and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffi-cient adhesion and conformability to function as a sealant in the tire.
24. A tire as in claim 23 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 3 to 8 parts per 100 parts by weight of the two elastomers, and the composition is devoid of fibrous filler.
25. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inexten-sible circumferential reinforcement, and a puncture sealing layer inside the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of from more than 50% to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps. with correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 30 to 70 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
26. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of from more than 50% to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F. of from 20,000 to 200,000 cps. with correspondingly from less than 50%
to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conform-ability to function as a sealant in the tire.
to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and an initial Mooney viscosity of from 40 to 60 ML at room temperature, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conform-ability to function as a sealant in the tire.
27. A tire as in claim 26 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetra-alkyl titanate crosslinking agent is from 3 to 8 parts per 100 parts by weight of the two elastomers.
28. A tire as in claim 27 in which the tetraalkyl titanate ester crosslinking agent is tetra-n-butyl titanate.
CLAIMS SUPPORTED BY SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY SUPPLEMENTARY DISCLOSURE
29. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of:
(A) a major proportion by weight of (i) a low molecular weight liquid elastomer or (ii) a mixture of a low molecular weight liquid elastomer and a tackifying or plasticiting substance;
with (B) a minor proportion by weight of a high mole-cular weight solid elastomer;
and (C) a crosslinking agent for the elastomers in amount effective to partially crosslink the elastomers to an extent sufficient to prevent the blend from flowing at elevated temperatures and centrifugal forces encountered in the tire in use, the blend having in the partially cross-linked state sufficient adhesion and conformability to func-tion as a sealant in the tire, the amount of (A) being from more than 50% to 90% by weight and the amount of (B) being correspondingly from less than 50% to 10% by weight, based on the combined weights of (A) and (B), the said low mole-cular weight elastomer in (A) being a liquid rubber having a Brookfield viscosity at 150°F. of from 20,000 to 2,000,000 cps and the said high molecular weight elastomer (B) having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., the amount of crosslinking agent (C) being sufficient to provide in the blend, after crosslinking, an initial Mooney viscosity of from 30 to 70 ML at room temperature when (A) is (i) and a peak Mooney viscosity of from 30 to 55 ML at 150°F
when (A) is (ii), and the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in tolerence at room temperature.
(A) a major proportion by weight of (i) a low molecular weight liquid elastomer or (ii) a mixture of a low molecular weight liquid elastomer and a tackifying or plasticiting substance;
with (B) a minor proportion by weight of a high mole-cular weight solid elastomer;
and (C) a crosslinking agent for the elastomers in amount effective to partially crosslink the elastomers to an extent sufficient to prevent the blend from flowing at elevated temperatures and centrifugal forces encountered in the tire in use, the blend having in the partially cross-linked state sufficient adhesion and conformability to func-tion as a sealant in the tire, the amount of (A) being from more than 50% to 90% by weight and the amount of (B) being correspondingly from less than 50% to 10% by weight, based on the combined weights of (A) and (B), the said low mole-cular weight elastomer in (A) being a liquid rubber having a Brookfield viscosity at 150°F. of from 20,000 to 2,000,000 cps and the said high molecular weight elastomer (B) having a Mooney viscosity of from 20 to 160 ML-4 at 212°F., the amount of crosslinking agent (C) being sufficient to provide in the blend, after crosslinking, an initial Mooney viscosity of from 30 to 70 ML at room temperature when (A) is (i) and a peak Mooney viscosity of from 30 to 55 ML at 150°F
when (A) is (ii), and the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in tolerence at room temperature.
30. A puncture sealing composition for a tubeless pneumatic tire comprising a fiber-free blend of A. a major proportion by weight of a low molecular weight liquid elastomer in admixture with a tacki-fying or plasticizing substance, and B. a minor proportion by weight of a high molecular weight solid elastomer, and a crosslinking agent for the elastomers in amount effective to partially crosslink the elas-tomers to an extent sufficient to prevent the blend from flowing at elevated temperatures and centri-fugal forces encountered in the tire in use, the blend having in the partially crosslinked state sufficient adhesion and conformability to function as a sealant in the tire, the amount of (A) being from more than 50% to 90% by weight and the amount of (B) being correspondingly from less than 50%
to 10% by weight, based on the combined weights of (A) and (B), the said low molecular weight elastomer being a liquid rubber having a Brook-field viscosity at 150°F of from 20,000 to 2,000,000 cnps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, the said crosslinking agent being selected from the following, present in the amounts recited:
from more than 0.5 to 2.0 parts of sulfur of sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid cura-tive;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative, and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60%
by weight of the blend, as measured in toluene at room temperature, and the peak Mooney viscosity of the blend in the partially crosslinked state being from 30 to 55 ML at 150° F.
to 10% by weight, based on the combined weights of (A) and (B), the said low molecular weight elastomer being a liquid rubber having a Brook-field viscosity at 150°F of from 20,000 to 2,000,000 cnps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, the said crosslinking agent being selected from the following, present in the amounts recited:
from more than 0.5 to 2.0 parts of sulfur of sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid cura-tive;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative, and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60%
by weight of the blend, as measured in toluene at room temperature, and the peak Mooney viscosity of the blend in the partially crosslinked state being from 30 to 55 ML at 150° F.
31. A puncture sealing composition as in claim 30 in which the liquid rubber is heat depolymerized natural rubber.
32. A puncture sealing composition as in claim 30 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid poly-butadiene, liquid polybutene, liquid ethelene-propylene-non-conjugated diene terpolymer rubber, and liquid isobutylene-isoprene copolymer rubber.
33. A puncture sealing composition as in claim 30 in which the high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a co-polymerizable monoethylenically un-saturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers; and saturated elastomers.
34. A puncture sealing composition as in claim 30 in which (A) is liquid heat depolymerized natural rubber in ad-mixture with a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst and (B) is solid cis-polyisoprene rubber.
35. A puncture sealing composition as in claim 30 in which the tackifying or plasticizing substance is selected from resin esters, aliphatic petroleum hydrocarbon resins, polyterpene resins, styrene resins, dicyclopentadiene resins, and resins prepared from the reaction of a mineral oil puri-fication residue with formaldehyde and with a nitric acid catalyst.
36. A puncture sealing composition for a tubeless pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of low molecular weight liquid elastomer having a Brookfield viscosity at 150°F of from 20,000 to 1,000,000 cps in admixture with a plasticizing or tacki-fying substance, and B. correspondingly from less than 50% to 10% by weight of high molecular weight solid elas-tomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, said blend being partially crosslinked to an ex-tent sufficient to provide in the blend a gel content of from 20 to 50% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150° F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encount-ered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
37. A puncture sealing composition as in claim 36 in which the said partial crosslinking is effected by subjecting the said blend to electron radiation.
38. A puncture sealing composition as in claim 36, devoid of fibrous filler, in which the said high mole-cular weight solid elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of conjugated diolefin with a minor proportion of a copolymerizable mono-ethylenically unsaturated monomer, copolymers of iso-butylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and satu-rated elastomers.
39. A puncture sealing compositon for a tubeless pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity of 150°F of from 20,000 to 1,000,000 cps in admixture with a plastic-izing or tackifying substance, and B. correspondingly from less than 50% to 10% by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212° F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50% by weight based on the weight of the blend as measured in tol-uene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150° F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire is use and the blend has sufficient adhesion and con-formability to function as a sealant in the tire.
40. A puncture sealing composition as in claim 39 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 2.5 to 8 parts per 100 parts by weight of the two elastomers, and the composition is devoid of fibrous filler.
41. A puncture sealing composition for a tube-less pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity of 150° F of from 20,000 to 2,000,000 cps in admixture with a plastici-zing or tackifying substance, and B. correspondingly from less than 50% to 10%
by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, said blend being partially crosslinked to an ex-tent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 30 to 55 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centri-fugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, said blend being partially crosslinked to an ex-tent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 30 to 55 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centri-fugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
42. A puncture sealing composition for a tube-less pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity of 150° F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst with B. correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and con-formability to function as a sealant in the tire.
43. A puncture sealing composition as in claim 42 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetraalkyl titanate crosslinking agent is from 3 to 8 parts per 100 parts by weight of the two elastomers.
44. A puncture sealing composition as in claim 42 in which the tetraalkyl titanate ester crosslinking agent is tetra-n-butyl titanate.
45. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vul-canized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area under-lying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential re-enforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a fiber-free blend of A. a major proportion by weight of a low molecular weight liquid elastomer in admixture with a tackifying or plasticizing substance, and B. a minor proportion by weight of a high molecular weight solid elastomer, said blend being partially crosslinked to an extent sufficient to prevent the blend from flowing at elevated temperatures and centri-fugal forces encountered in the tire in use, the partially crosslinked blend having suffi-cient adhesion and comformability to function as a sealant in the tire, the amount of (A) being from more than 50% to 90% by weight and the amount of (B) being correspondingly from less than 50% to 10% by weight, based on the combined weights of the two elastomers, the said low molecular weight elastomer being a liquid rubber having a Brookfield viscosity at 150° F of from 20,000 to 2,000,000 cps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212° F, the said composition containing crosslinking agent selected from the following, present in the amounts recited:
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative; and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in toluene at room temperature, and the peak Mooney viscosity of the blend in the partially crosslinked state being from 30 to 55 ML at 150° F.
from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
from more than 0.5 to 2.0 parts of quinoid curative;
from 0.1 to 1.0 part of radical generating curative;
from 2 to 10 parts of polyisocyanate curative; and from 2 to 10 parts of tetrahydrocarbyl titanate ester curative, the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in toluene at room temperature, and the peak Mooney viscosity of the blend in the partially crosslinked state being from 30 to 55 ML at 150° F.
46. A tire as in claim 45 in which the tackifying or plasticizing substance is selected from rosin esters, aliphatic petroleum hydrocarbon resins, polyterpene resins, styrene resins, dicyclopentadiene resins, and resins prepared from the reaction of a mineral oil purification residue with formaldehyde and with a nitric acid catalyst.
47. A tire as in claim 45 in which the said punc-ture sealing layer is disposed on the inside surface of the said liner.
48. A tire as in claim 45 in which the said seal-ing layer is sandwiched between the liner and the inside surface of the carcass.
49. A tire as in claim 45 in which the liquid rubber is heat depolymerized natural rubber.
50. A tire as in claim 45 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid polybutadiene, liquid polybutene, liquid ethylene-propylene-non-conjugated diene terpolymer rubber, and liquid isobutylene-isoprene co-polymer rubber.
51. A tire as in claim 45 in which the high mole-cular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proprotion of a conjugated diolefin with a monomer proportion of a copolymerizable monoethylenically un-saturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conju-gated diene terpolymers, and saturated elastomers.
52. A tire as in claim 45 in which the low molecular weight elastomer is liquid heat depolymerized natural rubber and the high molecular weight elastomer is solid cis-polyisoprene rubber.
53. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with fila-mentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of A. from more than 50 to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150°F of from 20,000 to 1,000,000 cps and a tackifying or plasticizing substance with B. correspondingly from less than 50 to 10% by weight of a high molecular solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212° F, said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centri-fugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
54. A tire as in claim 53, in which the said blend is devoid of fibrous filler, and in which the said high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conju-gated diolefin with a minor proportion of a copoly-merizable monoethylenically unsaturated monomer, co-polymers of isobutylene with a small amount of iso-prene, ethylene-propylene-non-conjugated diene ter-polymers, and saturated elastomers.
55. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with a filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of A. from more than 50 to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150°F of from 20,000 to 1,000,000 cps in admixture with a tackifying or plasticizing substance, and B. correspondingly from less than 50 to 10%
by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2.5 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20 to 50% by weight based on the weight of the blend as measured in toluence at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centri-iugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2.5 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20 to 50% by weight based on the weight of the blend as measured in toluence at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centri-iugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
56. A tire as in claim 55 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 2.5 to 8 parts per 100 by weight of the two elastomers, and the composition is devoid of fibrous filler.
57. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with fila-mentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferen-tial reinforcement, and a puncture sealing layer inside the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of A. from more than 50 to 90% by weight of liquid head depolymerized natural rubber having a Brookfield viscosity at 150°F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst with B. correspondingly from less than 50 to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 30 to 55 ML
at 150°F, whereby the blend is prevented from flowing at elevated temperature and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conforma-bility to function as a sealant in the tire.
at 150°F, whereby the blend is prevented from flowing at elevated temperature and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conforma-bility to function as a sealant in the tire.
58. A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmount-ing a vulcanized rubber carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumference tial reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture seal-ing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of A. from more than 50 to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150°F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purifica-tion product with formaldehyde and with nitric acid catalyst with B. correspondingly from less than 50% to 10%
by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said cross-linking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluence at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212°F, and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms, said blend being partially crosslinked by the said cross-linking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluence at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150°F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.
59. A tire as in claim 58 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetra-alkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetraalkyl titanate crosslinking agent is from 2.5 to 8 parts per 100 parts by weight of the two elastomers.
60. A tire as in claim 59 in which the tetra-alkyl titanate ester crosslinking agent is tetra-n-butyl titanate.
61. A tire as in claim 53 in which the said partial crosslinking is effected by subjecting the said blend to electron radiation.
62. A tire as in claim 59 in which the tetra-alkyl titanate ester crosslinking agent is tetrapropyl titanate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/557,713 US3981342A (en) | 1975-03-12 | 1975-03-12 | Puncture sealing composition and tire |
| US05/683,861 US4064922A (en) | 1975-03-12 | 1976-05-06 | Puncture sealing composition and tire |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1071785A true CA1071785A (en) | 1980-02-12 |
Family
ID=27071512
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA246,948A Expired CA1071785A (en) | 1975-03-12 | 1976-03-02 | Puncture sealing composition and tire |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1071785A (en) |
-
1976
- 1976-03-02 CA CA246,948A patent/CA1071785A/en not_active Expired
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| MKEX | Expiry |