Accelerator system for peroxide based curing systems

The present invention relates to filled elastomers which can be cured at low temperatures utilizing a quinoid/peroxide curing system in the presence of a select polar solvent accelerator. The select solvent accelerators which are utilized have the dual function of acting as both dispersing agents and curing accelerators. The instant invention herein includes the instant curing system, its use in a tire sealant composition, the puncture-sealing layer formed of the cured composition and the puncture-sealing tire.

BACKGROUND OF THE INVENTION 
Proper dispersion and distribution of curing agents in a rubber stock are 
desirable in order to obtain an efficient and homogenous cure. Although 
sufficient dispersion can usually be achieved with liquid curing agents, 
the use of such liquid agent is often inconvenient because of their 
instability and tendency to phase separate. While these problems can be 
avoided through use of solid curing agents, it is often essential to 
adequately subdivide and disperse such solid agents particularly when they 
are not appreciably soluble in the rubber stock. Exemplary solid curing 
agents for use with butyl rubber stock include p-benzoquinonedioxime and 
benzoyl peroxide on excipient bases such as calcium phosphate, flour and 
the like. When such curing systems are used in butyl rubber systems and 
heated to mild temperatures, below 50.degree. C., the butyl rubber 
undergoes an excessively slow cure which results in a product having a low 
cross-link density. Therefore, it is often desirable to use an accelerator 
with such solid dispersed systems. 
It is an object of the present invention to provide selected 
quinoid/peroxide based curing systems which are capable of yielding fast 
cure rates at mild temperatures particularly in the presence of selected 
accelerators. 
It is a further object of the present invention to provide a curing system 
capable of yielding fast cures in certain rubber stocks under mild 
temperature conditions. Therefore the main advantages of the utilization 
of the curing system of the present invention are as follows: (1) energy 
consumption can be minimized by effecting cure at mild instead of high 
temperature; (2) fast cure cycles are obtained which can translate into 
faster production times thus resulting in a more efficient, profitable 
commercial operation; and (3) the use of mild temperature curing can 
enable rubber parts to be produced which have physical properties which 
are preserved. These properties might have been adversely affected in the 
past when the parts were subjected to high temperature curing conditions. 
It is a further object of the present invention to utilize the selected 
quinoid/peroxide based curing systems in the preparation of a 
puncture-sealing layer of puncture-sealing tires. 
SUMMARY OF THE INVENTION 
It has now been discovered that filled elastomers can be cured at low 
temperatures utilizing a quinoid/peroxide curing system in the presence of 
a select polar solvent accelerator. The select solvent accelerators which 
are utilized have the dual function of acting as both dispersing agents 
and curing accelerators. The instant invention herein includes the instant 
curing system, its use in a tire sealant composition, the puncture-sealing 
layer formed of the cured composition and the puncture-sealing tire.

DESCRIPTION OF THE INVENTION 
According to the present invention, there is provided a process for curing 
an elastomer composition comprising at least one elastomeric synthetic or 
natural polymer at a temperature ranging from about 10.degree. C. to about 
200.degree. C., typically about 50.degree.-100.degree. C. which comprises 
carrying out the curing in the presence of about 0.01 to 20 parts by 
weight of at least one solid organic peroxide compound about 0.1 to 20 
parts by weight of a select polar solvent accelerator and about 0.01 to 10 
parts by weight of at least one quinoid vulcanization accelerator per 100 
parts by weight of elastomer composition (phr). 
The curing system of the present invention is especially advantageous as it 
can be utilized to cure rubber based systems at low temperatures ranging 
from about 20.degree. C. to 100.degree. C., preferably from 50.degree. C. 
to 100.degree. C. 
The polymers which can be utilized in the present invention are unsaturated 
and contain a minimum of about 0.1 mole % unsaturation. Typically, these 
polymers have a Mooney viscosity of at least about 25 (ML.sub.4 
/100.degree. C.). Representative useful elastomeric polymers include, but 
are not limited to: natural rubber, butyl rubber, ethylene-propylene 
terpolymer, polybutadiene, butadiene-styrene copolymers, 
butadiene-acrylonitrile copolymers, polyisoprene, isoprene-butadiene 
copolymers, hydrogenated or halogenated rubbers, and mixtures thereof. 
The present invention relates to accelerated cure systems for these rubbers 
which utilize peroxide and quinoid curing agents which are solid or 
impregnated on solid fillers in conjunction with select polar solvent 
accelerators. In a preferred mode of the instant invention, the quinoid 
vulcanizing accelerator is mixed with the rubber masterbatch prior to 
sequential or concurrent addition of the peroxide curing agent and the 
select polar solvent accelerator. Alternatively the peroxide curing agent, 
quinoid vulcanizing agent and the select polar solvent can be added in any 
order or conjointly. 
Typical organic peroxides which can be utilized in the curing system of the 
present invention include but are not limited to: benzoyl peroxide, 
t-butyl peroxypivalate, 2,4-dichloro-benzoyl peroxide, decanoyl peroxide, 
propionyl peroxide, hydroxyheptyl peroxide, cyclohexanone peroxide, 
2,5-dimethylhexyl-2,5-di(peroxybenzoate), t-butyl perbenzoate, dicumyl 
peroxide, 
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(t-butylpero 
xy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di-t-butyl peroxide, 
p-menthane hydroperoxide, cumene hydroperoxide, 
2,5-dimethyl-2,5-di(hydroperoxy)hexane, t-butyl hydroperoxide, lauroyl 
peroxide, t-amyl perbenzoate, or mixtures thereof. Preferred organic 
peroxides are benzoyl peroxide and t-butyl perbenzoate. Mixtures of two or 
more of the above peroxides can also be used. Other useful peroxide curing 
agents are known to those skilled in the art. 
It is usually desirable to support the peroxide curing agent on an inert 
filler or excipient material for reasons of safety and convenience in 
handling. 
Typical excipient materials which can be utilized as solid supports for the 
above-identified peroxide curing agents include wheat starch bases and 
inorganic phosphate bases. 
Typical commercially available supported peroxides which may be utilized in 
the instant invention include: LUPERCO AA from Pennwalt Chemicals which is 
32% benzoyl peroxide impregnated on a wheat starch base; and LUPERCO ACP 
from Pennwalt Chemicals which is 35% benzoyl peroxide impregnated on an 
inorganic phosphate base. As is well known to those of skill in the art, 
peroxides such as those described above, should be handled with the upmost 
care whether they be pure, supported on inert filler or combined with 
polymer. The tendency of peroxides to decompose or react violently 
requires the exercise of care and skill in their use and the skilled 
artisan will thoroughly familiarize himself with their properties before 
employing them. 
It is necessary to conjointly utilize a solid quinoid vulcanizing 
accelerator together with the peroxide curing agents. Suitable quinoid 
compounds include p-quinonedioxime, p-quinone dioxime diacetate, p-quinone 
dioxime dicaproate, p-quinone dioxime dilaurate, p-quinone dioxime 
distearate, p-quinone dioxime dicrotonate, p-quinone dioxime 
dinaphthenate, p-quinone dioxime succinate, p-quinone dioxime adipate, 
p-quinone dioxime difuroate, p-quinone dioxime dibenzoate, p-quinone 
dioxime di(o-chloro benzoate), p-quinone dioxime di-(p-chloro benzoate), 
p-quinone dioxime di-(p-nitro benzoate), p-quinone dioxime di-(m-nitro 
benzoate), p-quinone dioxime di-(3,5 dinitro benzoate), p-quinone dioxime 
di-(p-methoxy benzoate), p-quinone dioxime di-(n-amyl oxy benzoate), 
p-quinone dioxime di-(m-bromo benzoate), p-quinone dioxime di-(phenyl 
acetate), p-quinone dioxime di-cinnamate, p-quinone dioxime di-(n-phenyl 
carbamate), bis ethoxy methyl ether of quinone dioxime, mono-zinc salt of 
quinone dioxime, di-zinc salt of quinone dioxime, zinc chloride double 
salt of quinone dioxime, mono mercury salt of quinone dioxime, di-mercuric 
salt of quinone dioxime, mercuric chloride double salt of quinone dioxime, 
mono-barium chloride double salt of quinone dioxime, mono-cupric salt of 
quinone dioxime, mono-lead salt of quinone dioxime, mono-barium salt of 
quinone dioxime, mono-magnesium salt of quinone dioxime, mono-calcium salt 
of quinone dioxime, silver salt of p-quinone dioxime, 1,4-naphthoquinone 
dioxime, chloro methyl quinone dioxime, 2,6-dimethyl 1,4-quinone dioxime, 
2-phenyl-1,4-quinone dioxime, 2-benzyl-1,4-quinone dioxime, 
2-ethyl-1,4-quinone dioxime, thymo quinone dioxime, 2-chloro-p-quinone 
dioxime, thymo quinone dioxime dibenzoate, thymo quinone dioxime 
diacetate, p-quinone dioxime phosphochloride, and the like, and mixtures 
thereof. 
The inert fillers or excipient materials consist of particles having an 
average maximum particle size of 50 microns. The preferred particle size 
of inert fillers for use in the instant invention are particles less than 
ten microns, most preferably averaging between one and five microns in 
diameter. The solid peroxides and quinoids which are employed in the 
present invention each consist of particles having an average maximum 
particle size below 50 microns, preferably below ten microns, and most 
preferably between one and five microns. 
Additional vulcanizing and co-curing agents can additionally be 
incorporated into the rubber mix. Suitable vulcanizing and co-curing 
agents which can be utilized in the instant invention include but are not 
limited to: sulfur and sulfur-containing vulcanizing agents such as 
tetrathiuram disulfide and dipentamethylene thiuram tetrasulfide; 
vulcanization accelerators such as thiuram compounds, dithioacid salts and 
thiazole compounds. 
Typical amounts of peroxides utilized in the present invention are from 
about 0.01 to 20, preferably from about 0.5 to 10 phr. The total amount of 
vulcanization agents and/or co-curing agents which are generally used are 
amounts ranging from about 0.01 to 20 phr. Quinoid compounds are typically 
utilized in amounts ranging from about 0.01 to 10 phr. The select polar 
solvent accelerators described below in detail are typically used in 
amounts ranging from about 0.1 to 20, preferably about 0.5 to 5 phr. 
In the present invention it is preferred that the peroxide curing compounds 
be either predispersed in a select polar solvent accelerator prior to 
incorporation into the rubber stock, or sequentially or conjointly added 
into the rubber masterbatch after the addition of the select polar solvent 
accelerator. 
Suitable select polar solvent accelerators include but are not limited to: 
water (including aqueous solutions of acids and bases such as shown in 
Table 2), primary, secondary and tertiary alcohols and polyols such as 
aliphatic, cycloaliphatic and aromatic alcohols containing from one to 
twelve carbon atoms, for example, methanol, ethanol, propanol, butanol, 
n-octanol, n-heptanol, n-hexanol, iso-octanol, 2,2-dimethyl-hexan-6-ol, 
t-amyl alcohol, 4-methyl cyclohexanol, benzyl alcohol, butanediol, 
propylene glycol and ethylene glycol; ketones, such as ethyl methyl ketone 
and cyclohexanone; aldehydes such as benzaldehyde, acetaldehyde and 
propylaldehyde; ethers such as tetrahydrofuran, dioxane, dioxalane and 
diethyl ether; alkyl and aromatic nitriles such as propylnitrile and 
benzonitrile; acids such as phosphoric acide, acetic acid and proprionic 
acid; and bases such as NaOH; esters such as dimethyl succinate and 
diethyl succinate. Dipolar, aprotic compounds such as dialykyl formamides, 
dialkyl acetamides and dialkylsulfoxides such as dimethylsulfoxide are 
also useful. Mixtures of these accelerators can be utilized. 
The curing system of the instant invention can be utilized in the formation 
of a puncture-sealing layer of a puncture-sealing tire. This 
puncture-sealing layer is located on the inner surface of a tubeless tire 
either on the innermost surface or between the carcass and another layer 
with the puncture-sealing layer consisting essentially of a cured 
composition formed from ingredients comprising: 
(a) a network-forming amount of a network-forming polymer elastomer 
containing at least about 0.1 mole % unsaturation, 
(b) a tackifying amount of a primary tackifier polymer, preferably a liquid 
polybutene, having a number average molecular weight ranging from about 
500 to about 5000, 
(c) the curing system of the instant invention. For example, typical 
amounts of (a) and (b) are about 100 pbw and about 525 pbw, respectively. 
The puncture-sealing tire herein has a puncture-sealing layer which resists 
migration, provides a high degree of adhesion, and resists blow through. 
The aforementioned cured composition can be produced independent of a tire 
and sold to tire manufacturers for use in the manufacture of 
puncture-sealing tires. Moreover, the aforementioned ingredients can be 
sold in the form of a sealant system to tire manufacturers who use the 
system to produce said cured composition. 
Typical network-forming polymers include EPDM polybutadiene, hydrogenated 
polybutadiene, butyl rubber, halo butyl rubber (e.g. chloro- and bromo-), 
acrylonitrile-butadiene copolymer, styrene butadiene copolymer, natural 
rubber, cis-polyisoprene and the like. Mixtures of two or more of the 
above polymers can also be used. 
The primary tackifier polymers used in the invention are polymers of 
relatively low molecular weights (Mn about 500 to about 5000) which often, 
but not necessarily are liquid at room temperature (about 20.degree. C.). 
Many structural types of polymers are useful including ethylene-propylene 
copolymer (EPC), ethylene-propylene-diene terpolymer, polybutadiene (PBD), 
hydrogenated PBD, butyl rubber (BR), polypropylene, 
acrylonitrile-butadiene copolymer (ANB), styrene-butadiene rubber (SBR), 
depolymerized natural rubber (DPR) and polybutenes. Because of their cost, 
availability and properties the polybutenes are particularly useful. 
Such polybutenes preferably have a number average molecular weight 
exceeding about 1000 as this has an effect on minimizing the possibility 
of its migration into adjacent tire components. While the primary 
tackifier can be utilized in an amount of at least about 300 phr, 
typically it is utilized in an amount ranging from about 300 to about 900 
phr. It is preferably prepared by polymerizing an isobutylene rich stream 
with a metal halide catalyst and preferably has a polymer backbone 
structure resembling polyisobutylene. Very suitable polybutenes are 
available under the trademark Indopol, e.g. Indopol H-300 and Indopol 
H-1900, from Amoco. The manufacturer indicates that these Indopols have a 
polymer backbone structure resembling isobutylene and that Indopol H-300 
has a viscosity ranging from about 627 to 675 centistokes at 100.degree. 
F. (ASTM D-445) and Indopol H-1900 has a viscosity ranging from 4069 to 
4832 centistokes at 100.degree. F. (ASTM D-445). The number average 
molecular weights (Mn) of these materials are about 1290 to 2300, 
respectively, as determined by vapor pressure osmometry. 
Additional ingredients for use in preparation of the sealant layer are 
disclosed in the application of DeTrano et al. titled "EPDM-Based Sealant 
Compositions And Puncture-Sealing Tires Containing Same" filed 
concurrently herewith which is herein incorporated by reference. 
Utilization of the instant improved rubber curing system is displayed in 
the following Examples 1 through 30. 
PREATION OF RUBBER MASTERBATCH FOR EXAMPLES 
A butyl rubber masterbatch was formed from 15 parts by weight of a 
commercial grade of butyl rubber, 78 parts by weight of polyisobutylene 
containing 5 parts by weight of a commercially available aliphatic resin 
tackifier (Piccotac B-BHT), 7 parts by weight of reinforcing grade carbon 
black, and 0.55 parts by weight of solid p-benzoquinonedioxime. 
Examination was made on the representative vulcanization system with or 
without various polar solvent vulcanization accelerators and peroxide 
curing agents in the following examples. 
EXAMPLES 1 THROUGH 4 AND CONTROL 5 
Samples of the butyl rubber masterbatch were blended in a Brabender mixer 
operating at 60 rpm at a stock temperature at 35.degree.-40.degree. C. 
Examples 1 through 4 shown in Table 1 display the effect of a select polar 
solvent, 1-octanol, upon the curing rate of the butyl rubber masterbatch 
further containing a peroxide curing agent. Control 5 is a comparative 
Example displaying the curing of the butyl rubber masterbatch with a 
peroxide curing agent in the absence of 1-octanol, the select polar 
solvent. 
EXAMPLES 6-28 
For each of the following Examples 6-28, 100 parts by weight of the butyl 
rubber masterbatch was charged into a Brabender mixer operating at 60 rpm 
at ambient temperature. The rubber stock temperatures rose to between 
35.degree. and 40.degree. C. during mixing. In Examples 6 through 24 a 
select polar solvent accelerator in an amount of 5.15 parts by weight was 
added to the rubber stock and mixed for three minutes. Thereafter 7.35 
parts by weight of LUPERCO AA, a peroxide curing agent, was sequentially 
added to the mixture of rubber and accelerator. The cure onset time, 
T.sub.1, for each mixture was recorded in minutes as the time at which 
curing occurred after blending. The Brabender mixer registers the torque 
during mixing of the rubber composition in units of meter-grams. The time 
T.sub.2 was then recorded at which the torque measurement increased by 100 
meter-grams from the lowest torque measurement recorded during mixing of 
the rubber composition after the addition of both the peroxide curing 
agent and the select polar solvent accelerator. 
The cure rate index, T.sub.2 -T.sub.1, was calculated for each select polar 
solvent accelerator utilized. The results are demonstrated in Table 2. 
Most of the cured rubber stocks produced in Examples 6 through 23 were 
given a hot flow test, the results of which are displayed in Table 2. In 
all hot flow tests, a 0.5 to 0.55 gram sample of cured rubber stock was 
placed on acetone-cleaned, microscope slide inclined at an angle of 
30.degree. . The distance which the test stock flowed down the glass slide 
after two hours at 150.degree. C. was measured in millimeters. These 
samples were not post heated and the results are listed in Table 2 under 
"After Mixing" as the samples were directly removed from the Brabender 
mixer. Similarly a 0.5 to 0.55 gram sample of each cured rubber stock was 
post, heated for 30 minutes at 80.degree. C. in an oven and given the same 
flow test. The results of this test are shown in Table 2 under the column 
heading "Post Heated". 
Examples 25 through 28 shown in Table 3 display the use of polar solvents 
which cannot be utilized in the present invention as the Brabender tests 
displayed a rate cure index greater than 6.0. Plus signs after number in 
Table 3 display that no further measurements were taken after that time or 
distance. 
TABLE 1 
__________________________________________________________________________ 
V.sub.R .sup.(4) .times. 10.sup.2 
MEASURED AFTER MINUTES AT 
Butyl Rubber 
Peroxide Curing 
1-Octanol.sup.(3) 
80.degree. C. POST CURING 
Master Batch 
Agent Parts By 
Cure Onset 
Initial 
Example No. 
Parts By Weight 
Parts By Weight 
Weight 
Time (Minutes) 
Mixing 
15 Min. 
30 Min. 
60 
__________________________________________________________________________ 
Min. 
1 100 7.35.sup.(1) 
5.15 5 1.22 1.39 1.14 1.12 
2 100 7.1.sup.(2) 
5.15 4 1.42 1.57 1.19 1.20 
3 100 7.1.sup.(2) 
2.58 6.5 1.13 1.07 1.20 1.11 
4 100 7.1.sup.(2) 
1.29 9 0.48 0.90 0.89 0.83 
Control 5 
100 7.1.sup.(2) 
none 28.sup.+(5) 
Dissolved.sup.(6) 
Dissolved.sup.(6) 
Dissolved.sup.(6) 
Dissolved.sup.(6) 
__________________________________________________________________________ 
.sup.(1) 32% benzoyl peroxide with wheat starch excipients (Pennwalt 
Chemicals) 
.sup.(2) 35% benzoyl peroxide with calcium phosphate excipients (Pennwalt 
Chemicals) 
.sup.(3) Alfol 8 (Conoco Chemicals) 
.sup.(4) Crosslink density, i.e., volume fraction of rubber remaining in 
the swollen sample 
.sup.(5) No curing displayed after 28 minutes 
.sup.(6) Sample did not cure and therefore dissolved in solvent 
TABLE 2 
__________________________________________________________________________ 
Brabender Plasticorder 
Hot Flow Index.sup.(2) 
Response After Post 
Example No. 
Select Polar Solvents 
T.sub.1 
T.sub.2 
T.sub.2 - T.sub.1 
Mixing 
Heated 
__________________________________________________________________________ 
6 Dimethylformamide 
0.4 
1.3 0.9 No Flow 
No Flow 
7 Dimethylacetamide 
0.7 
1.4 0.7 No Flow 
No Flow 
8 Acetic Acid 1.2 
1.9 0.7 No Flow 
No Flow 
9 Dimethylsulfoxide 
1.5 
2.6 1.1 No Flow 
0.50 
10 Benzyl Alcohol 
1.0 
2.2 1.2 0.50 0.62 
11 Benzonitrile 6.2 
9.9 3.7 0.25 0.32 
12 Cyclohexanone 
6.0 
10.0 
4.0 0.31 0.54 
13 Butanediol 3.5 
6.2 2.7 0.67 1.62 
14 1% Sodium Hydroxide.sup.(1) 
6.7 
9.7 3.0 Not Tested 
Not Tested 
15 1% Phosphoric Acid.sup.(1) 
6.2 
9.9 3.7 Not Tested 
Not Tested 
16 Acetophenone 6.0 
11.4 
5.4 0.31 0.77 
17 t-Amyl Alcohol 
6.0 
10.7 
4.7 0.94 1.46 
18 4-Methyl Cyclohexanol 
6.0 
11.5 
5.5 0.94 1.23 
19 Benzaldehyde 6.5 
10.5 
4.5 1.00 1.92 
20 Diethylsuccinate 
6.5 
12.0 
5.5 0.87 1.00 
21 Water.sup.(1) 
7.5 
11.5 
4.0 Not Tested 
Not Tested 
22 Water 7.0 
12.0 
5.0 Not Tested 
Not Tested 
23 1-Octanol 6.7 
11.9 
5.2 1.00 1.00 
24 42.5% Phosphoric Acid.sup.(1) 
9.0 
13.5 
4.5 Not Tested 
Not Tested 
__________________________________________________________________________ 
.sup.(1) Accelerator present at the 0.74 wt. percent level 
.sup.(2) Index relative to Example 23 = 13 mm Flow 
TABLE 3 
__________________________________________________________________________ 
Brabender Plasticorder 
Hot Flow Test 
Select Response After Post 
Example No. 
Polar Solvent 
T.sub.1 
T.sub.2 
T.sub.2 - T.sub.1 
Mixing 
Heated 
__________________________________________________________________________ 
25 Dodecylmercaptan 
2.5 20.sup.+ 
20.sup.+ 
1.00 1.23 
26 Nitrobenzene 
9.5 18.0 
8.5 1.19 1.31 
27 Dimethylaniline 
20.sup.+ 
-- -- 3.sup.+ 
3.sup.+ 
28 None 20.sup.+ 
-- -- Not Tested 
Not Tested 
__________________________________________________________________________ 
The following Examples 29 and 30 display the utilization of the instant 
curing system in the preparation of a puncture-sealing layer of a 
puncture-sealing tire. 
______________________________________ 
Example 29 
Example 30 
______________________________________ 
EPDM (EPsyn 55) 15 15 
Polybutene (Indopol H-1900) 
85 50.5 
Polybutene (Indopol H-300) 
-- 29 
Resin Tackifier (Piccotac 
-- 5.5 
B-BHT) 
Carbon Black (N-326) 
5 5 
p-benzoquinonedioxime 
1 1 
Peroxide Catalyst consisting 
14.4 14.4 
by weight of 50% LUPERCO AA, 
17.3% n-octanol, and 32.7% 
Indopol H-300 
______________________________________ 
These compositions were prepared as follows: A masterbatch of the EPDM, 5 
parts of the Indopol H-1900, the carbon black and the 
p-benzoquinonedioxime was prepared in a Brabender Plasticorder operating 
at 60.degree. C. and 60 rpm. The resultant mix was then worked on a 
two-roll mill. The batch was then solution blended in hexane with the 
remainder of the polybutene and other tackifier (if any) and was 
subsequently stripped of solvent in a vacuum oven to produce a dried 
material. The Peroxide Catalyst was then added to the dried, material in 
the Brabender Plasticorder at 60 rpm with no external heat. Samples were 
then oven cured at 80.degree. C. for 15-30 minutes. 
The above compositions were evaluated for their ability to adhere to a 
metal surface (as might be encountered in the tire by a puncturing nail). 
Using an Instron Tensile Tester fitted with fixtures designed for the 
test, the steel probe of the Tester was brought against the surface of a 
0.18 inch thick sheet of sealant composition and held at predetermined 
loading for a specified time before being pulled away from the surface at 
the various rates as specified below. The energy expended in separating 
the probe from the sealant was measured and recorded. The data are 
reported below (wherein the separation rate is in terms of speed of the 
Instron crosshead and the separation energy is in joules, with greater 
adhesion being indicated by greater separation energy). 
______________________________________ 
Separation Rate 
20 inches/ 
2 inches/minute minutes 
Compressive Load, lbs 
.5 1 3 5 1 5 
______________________________________ 
Example 29 .25 .21 .33 .41 .51 1.05 
Example 30 .39 .30 .53 .70 .68 1.61 
______________________________________ 
The above data indicates superior adhesion-to-metal characteristics and is 
significantly better than is obtained on testing of a commercially 
available sealant composition. 
The aforementioned cured material is readily pressed against a tire inside 
wall to fix it in place to form a puncture-sealing tire with a 
puncture-sealing layer with excellent adherence properties and resistance 
to migration. Typically, the sealant is used to protect the crown area of 
the tire (i.e., the area in back of the tread from shoulder to shoulder). 
In some cases, it can extend from the middle portion of one of the side 
walls to the middle portion of the other. In extreme cases, the sealant 
material can extend from bead to bead on the inner surface of the tire. 
The compositions of Examples 29 and 30 also demonstrate excellent 
resistance to migration, puncture filling properties and resistance to 
blow through after filling and sealing. 
Good results are also obtained when up to 70% of the EPDM is replaced by 
one or more other network-forming polymers, e.g. polybutadiene, 
hydrogenated polybutadiene, butyl rubber, halo butyl rubber, 
acrylonitrile-butadiene copolymer, styrene butadiene copolymer, natural 
rubber, and cis-polyisoprene. 
Good results are also obtained when the polybutene is replaced with other 
low molecular weight (Mn of about 500 to 5000) tackifiers such as 
ethylene-propylene copolymer, ethylene-propylene-diene terpolymer, 
polybutadiene, hydrogenated polybutadiene, butyl rubber, polypropylene, 
acrylonitrile-butadiene copolymer, styrene-butadiene rubber and 
depolymerized natural rubber. 
This invention and compositions made according to it find use in many 
applications where elastomeric compositions are cured, particularly in 
situ. Specific areas of use besides tire sealants used to coat the insides 
of puncture self-sealing vehicle tires include roofing compounds and 
caulking compositions. Other areas of utility will be apparent to those 
skilled in the art upon careful study of this specification. 
While the foregoing describes certain preferred embodiments of the 
invention, modifications will be readily apparent to those skilled in the 
art. Thus, the scope of the invention is intended to be defined by the 
following claims.