CA1042330A - Radial ply pneumatic tires and process for their manufacture - Google Patents
Radial ply pneumatic tires and process for their manufactureInfo
- Publication number
- CA1042330A CA1042330A CA243,410A CA243410A CA1042330A CA 1042330 A CA1042330 A CA 1042330A CA 243410 A CA243410 A CA 243410A CA 1042330 A CA1042330 A CA 1042330A
- Authority
- CA
- Canada
- Prior art keywords
- tire
- rubber
- green strength
- bis
- rubber composition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D30/00—Producing pneumatic or solid tyres or parts thereof
- B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
- B29D30/36—Expansion of tyres in a flat form, i.e. expansion to a toroidal shape independently of their building-up process, e.g. of tyres built by the flat-tyres method or by jointly covering two bead-rings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D30/00—Producing pneumatic or solid tyres or parts thereof
- B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
- B29D30/08—Building tyres
- B29D30/20—Building tyres by the flat-tyre method, i.e. building on cylindrical drums
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/02—Carcasses
- B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
- B60C9/08—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship the cords extend transversely from bead to bead, i.e. radial ply
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/02—Carcasses
- B60C9/14—Carcasses built-up with sheets, webs, or films of homogeneous material, e.g. synthetics, sheet metal, rubber
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- C08C19/00—Chemical modification of rubber
- C08C19/30—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule
Abstract
ABSTRACT OF THE DISCLOSURE
The carcass plies of a radial ply pneumatic tire are made from cord reinforced rubber which has a high green strength. The rubber has labile cross-links therein, which confer high green strength on the rubber, but which are labile to heat and shear, so that the uncured rubber pro-cesses normally. Such high green strength rubbers are better able to stand up to forces experienced during radial tire manufacture.
The carcass plies of a radial ply pneumatic tire are made from cord reinforced rubber which has a high green strength. The rubber has labile cross-links therein, which confer high green strength on the rubber, but which are labile to heat and shear, so that the uncured rubber pro-cesses normally. Such high green strength rubbers are better able to stand up to forces experienced during radial tire manufacture.
Description
This invention relates to radial ply pneumatic tires, processes for their manufacture and cGmponents useful in their manufacture.
A radial ply pneumatic tire is a tire in which the carcass comprises a number of plies (normally 2 to 4, optional-ly up to 6) of cord reinforced rubber, the cords of which are substantially parallel to one another and extend radially across the tire, generally at about a right angle to the median circumferential line of the tire. An angle of from 75 to 90 of the cords to the median circumferential line is generally considered to characterize a radial ply tire.
The conventional or bias ply pneumatic tire has the cords of ` its carcass plies extending around the tire carcass and on the bias, i.e. at a more acute angle to the median circum-ferential line. Radial tires have a much re flexible car-cass side structure, with much more side wall flex in opera-tion, as compared with bias ply tires. In order to retain necessary road handling ability, radial ply tires must be ~- provided with belts below the tread portion, the belts having strong substantially inextensible fibres extending essentially circumferentially around the tire.
The manufacturing processes generally used for radial tire manufacture put demands upon the physical pro-perties of the rubber compounds used in their carcasses, when in the green or uncured state, which are different from those requiredin bias ply tire manufacture. The carcass of the tire contains a pair of circular beads, normally of steel embedded in rubber, which in the finished tire define the - ~ inner peripheral edges of the tire, and in a tubeless pneuma-tic tire form part of the sealing assembly between the wheel rim and the tire. The tire carcass comprises an inner liner, -- 1 - q~' 10423;~0 which is preferably of substantially air impervious rubber (e.g. bromobutyl), and the plies of cord reinforced rubber extend from bead to bead across the tire. Belts, sidewalls and tread components are applied over the carcass. The radial tire carcass is assembled and shaped with the rubber compounds of the various constituents in the green or uncured state. After this assembly and shaping, the belts, sidewall components and tread components are applied, again in an uncured state, and the assembled tire is cured or vulcanized.
Processes of manufacturing radial tires, whether ~ . .
they are one stage or two stage processes, involve the initial assembling of beads, inner liner and carcass plies as a cylinder of substantially planar wall cross section, the rubber of the carcass plies being in the green state, and the subsequent alteration of the shape of this assembly to a torus.
This alteration of shape involves extension of the green rub-ber compounds at various locations of the carcass by as much as 200 - 300%.
The corresponding change of shape occurs, in the manufacture of a conventional bias ply tire, only when the complete tire has been assembled as a cylinder on a building drum, with the sidewall, tread and any necessary reinforcing belts applied. The assembled tire is transferred to a mold in which it is shaped, the mold is totally closed and the whole subjected to heat and pressure to effect curing.
In contrast, however, the radial tire carcass must be shaped, to reach approximately its final external diameter, before it i8 combined with the tread and belt, and depending on the process, the sidewall portions and hence before it is put into a mold for curing. This is because a radial ply tire has to have incorporated therein reinforcing belts of substan-;
~ - 2 -tially inextensible fibrou~ material, the fibres of which extend circumferentially around the tire, below the tread.
These belts cannot be extended circumferentially, and so they must be applied after shaping the green radial tire car-cas to approximately its final diameter. Thus the green strength of the rubber used in the carcass plies must be sufficient, without the aid of external constraining struc-.
tures such as molds, to withstand stresses applied in the i shaping operation, and under conditions of temperature, etc., ;~
~` 10 normally encauntered in tire manufacturing operations. As noted, this means in practice that the rubber in the green ,, state must be able to withstand elongations of 200% or more.
'~ If the rubber compound used in the plies of the car-~' cass has insufficient green strength to withstand this exten-ir i3 sion and the forces experienced when such extension is caused : `' in commercial manufacture, the cords of the radial plies may i~ ~ not be held in their desired position in the rubber, and may even strike through to the inner liner of the tire or the carcass may thin down or even split. The maintenance of the ~ cords in their preset, predetermined relationship to one another, embedded in the rubber of the carcass plies, through-out the manufacturing process, is important in producing radial tires of high quality.
, .
Conventional synthetic rubbers such as rubbery ~t~ styrene-butadiene copolymers (SBR), synthetic polyisoprene - .~
and polybutadienes are deficient in green strength. For radial tire manufacture, it has been found necessary to use natural rubber, alone or in admixture with synthetic rubbers, so as . .
to obtain a carcass rubber composition of sufficient green strength.
In one of the re commonly used processes for ma~ing ~042330 radial tires, a two stage operation is adopted, in which, in a first stage, the carcass is assembled incorporating the inner liner, beads and radial carcass plies, and shaped to the desired toroidal shape while in the green state. Then in a second stage, the sidewalls, circumferential belts and tread are applied, again in the green state, and then the assembled green tire is heated under pressure in a mold to .
; effect curing. There may be some time lapse between the first and second stages of the operation in which case the first ; 10 stage assembly is usually deflated and then reinflated prior to the second stage. The uncured rubber of the carcass plies ; must be able to withstand being held under stress and in an elongated condition for some period of time without retracting or otherwise deforming to allow movement or strike-through of the cords embedded therein. Conventional synthetic rubber compositions do not have stress - relaxation characteristics in the green state satisfactory to meet these criteria.
In accordance with the present invention, signifi-- cant reduction of these problems of manufacture of radial tire carcasses i8 accomplished by the use, in the rubber-tire cord ., ~
carcass ply sheets of the tire, of green rubber compositions based upon synthetic rubbers which have small numbers of shear and/or heat sensitive labile cross-links, which behave as high green strength rubbers at ordinary temperatures, but as ordinary ,, ~ .
rubbers under the shear and elevated processing temperatures used in a tire factory. An example of such a synthetic rubber ~-~ is a rubbery styrene-butadiene polymer containing a small .. , ; .
~ amount of tertiary amine groups, reacted with a dihalogen com-.. .. .
pound.
Thus according to a first aspect of the present in-., vention, there i~ provided a radial ply pneumatic tire com-:
prising a carcass portion and a belt-tread-sidewall portion;
the carcass portion thereof having an inner rubber liner, a pair or generally circular, substantially inexten-sible beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composition, said cords being mutually parallel and extending at an angle of from about 75 to about 90 to the circumferen-' tial median line of the tire;
.~' 10 the tire carcass rubber composition comprising a ,, '~ high green strength rubber composition comprising a synthetic ~ rubber having labile cross-links, ; the combined carcass and belt-tread-sidewall portions having been vulcanized by the action of heat.
According to another aspect of the present invention, there is provided a process of making a radial ply pneumatic tire having an-inner rubber liner, a pair of generally circu-iar beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composi-;i- tion, which comprises:
~- encasing a plurality of closely spaced, generally ~, mutually parallel tire cord fibres in high green strength tire carcass rubber composition comprising a synthetic rubber having .. labile cross-links so as to form a sheet of rubber-tire cord fabric;
forming a generally cylindrical a9semb1y having an inner layer of tire liner rubber compo8ition, a plurality of outer layers comprised of said sheets of rubber-tire cord ~ 30 fabric, the cords thereof extending radially at an angle of from about 75 to about 90 to the median line of said - _ 5 _ generally cylindrical assembly, and two substantially inex-tensible generally circular beads of uncured rubber covered metal, said beads being located one at each axial end portion of the generally cylindrical assembly;
expanding the central portion of the generally cylin-drical assembly relative to the axial end portions thereof to change the shape of the assembly to toroidal;
adhering thereto the belt, tread and sidewall assemblies;
-- 10 and subsequently curing the assembly by heating.
In the accompanying drawings:
- Figure 1 is a diagrammatic cross sectional illustra-~¦ tion of a first stage in the manufacture of a carcass of a i radial tire according to the invention;
Figure 2-is an illustration similar to Figure 1 showing a subsequent, intermediate step of the manufacture;
.~.
Figure 3 is an illustration similar to Figuresl and ~, 2 showing a third stage in the manufacture.
Figures 1 to 3 show schematically the shaping of a radial ply carcass. The specific illustration shows a carcass having two plies of tire cord fabric. As shown in Figure 1, the carcass is built on a building drum which comprises a cen-tral portion 16 and two outer portions 17 and 18. First, the ii chafers 15 are positioned on the drum - the chafer is compounded - rubber well known in the art which serves to protect the car-. ;., .
~ cass of the finished tire against the chafing action of the : i i ~~i wheel rim. The inner liner 11 is next laid down 90 that the -:, outer edges of the liner are in contact with each chafer at i what will be the toe region of the tire. A first ply of rub-~, 30 ber-tire cord fabric 12 i8 then added, followed by a second ~-~ ply 13, the length of each ply being such that it overlaps the chafer. The bead assembly 14 is next positioned onto the assembly - a bead assembly is well known in the art and com-prises a combination of wires, generally in the form of a multistrand`bead and optionally includes a shaped rubber com-pound adhered to the combination~of wires. The product is thus a planar walled cylinder of various materials.
Figure 2 illustrates an intermediate stage in the ~- process of changing the shape of the cylindrical form of Figure 1 to a toroidal shape of the finished tire. The bead assembly is mechanically held in position relative to the chafer and plies but is moved inwardly so that the centre sec-tion of the carcass assembly ves upward. To accommodate ~, .
this, the central portion of the drum is mechanically reduced n size, in its axial direction. The upward movement of the central portion of the carcass is assisted by inflation which ; may be by directly applying air pressure, or by applying air ,, -f`~ pressure to a membrane forming part of the central portion of .'`1 ' .
the drum or may be by purely mechanical means. This upward movement of the central portion of the carcass is an actual f expansion of this portion, the expansion occurring in the cir-cumferential portion where the tread will subsequently be .
~ ~ applied.` This expansion causes a thinning down of the thick-.....
ness of the rubber and a spreading, in relation one to the . other, of the fibre cords.
-~ - Figure 3 shows a further stage in the expansion and changing to toroidal shape with the bead assemblies being almnst at their final positions and the ply endings having been turned up and around the bead assemblies. On further expansion to - its final dimensions, the belts, tread and sidewalls will be applied.
- During the expansion stage, the carcass requires ~042330 a certain minimum level of strength so that the whole assembly does not rupture or thin down unevenly. On changing from the cylindrical form to the toroidal form the circum-ference of the assembly increases by from about 150% to about 300% in length. The time involved in causing the change in shape is variable depending on the particular manufacturing process involved but may range from as low as about 2 to 3 seconds to as long as 20 to 30 seconds. A polymer having high strength provides the necessary properties to meet these characteristics.
In a radial tire manufacturing process, the uncured tire carcass is maintained in the configuration shown in Figure 3 while applying the remaining components. The green tire carcass is thus being maintained with the uncured rubber compositions of the plies in a stressed condition. There is a natural tendency of rubber compositions to relax when held . ,1 .
- ~ under stress conditions, thereby losing strength. If this happens, the tire cords may move or even strike through the plies, 12, 13, and even through the inner liner 11, thereby ` !
spoiling the assembly.
A ply of the carcass comprises a number of parallel-^~ disposed tire cords encased in an uncured rubber composition.
-s, The cords are each surrounded on all sides by the rubber com-~ position. The cords are generally of steel, rayon, glass, :,, types of nylon, polyester, cotton or the like, and are assembled ~, in a manner well known in the art. The uncured rubber com-pound is applied by calendering onto the cord assembly, to form the ply. The cords may be pretreated with suitable adhesive compositions to improve their adhe8ion to the rubber composi-tion.
According to the present invention, the uncured ~ 104Z330 rubber compound which is used in the rubber-tire cord carcass plies is based at least in part upon a high green strength synthetic rubber having labile cross-links. Such rubber com-pounds have suitable characteristics in the green state to be able to withstand the deformations and extensions, the exten-sion at the required rate, and the stress-relaxation demands, experienced in commercial radial tire manufacture, at the tem-peratures generally encountered during such manufacture which are normally from about 15C to about 40C, but may even be as high as 50C. An example of a synthetic rubber upon which these rubber compounds can be based is a rubbery SBR polymer containing small amounts of tertiary amine groups in the , polymer chains, the polymer having been reacted with a dihalo-;- ~ gen compound capable of reacting with the tertiary amine ,. ~ , groups in the polymer.
The SBR polymer used in such a composition is preferably a rubbery styrene-butadiene polymer containing from about 60 to about 85% by weight, most preferably from about 70 to 82% by weight, of butadiene and from about 40 to about 15% by weight, most preferably from about 30 to about 18% by weight, of styrene, ~-` and containing from about 0.5 millimoles to about 10 millimoles, ;~ preferably from about 0.75 millimoles to about 7.5 millimoles, and most preferably from about 2.5 to about 7.5 millimDles, of ~ound tertiary amine groups per 100 grams of polymer. The tertiary .
,~ amine groups are suitably introduced by copolymerizing with the styrene and butadiene a suitable amount of a tertiary amine group containing monomer, the tertiary amine groups of which are sub-stantially unaffected by the polymerization.
Preferred suitable tertiary amine group containing monomers sre dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate. Dimethylaminoethyl methacrylate i8 especially preferred. This monomer readily copolymerizes with butadiene and styrene in conventional emulsion polymerization recipes and systems commonly used for making SBR polymers for synthetic rubber applications. It has a copolymerization reactivity similar to that of the copolymerizing monomers in such a system. A
rubbery polymer is obtained with ~ertiary amine groups distributed along and among the polymer chains.
Of course, other similar C4 - C6 conjugated diolefinic hydrocarbons such as isoprene, piperylene and 2,3-dimethyl-butadiene-1,3 can be substituted for the commoner and cheaper butadiene-1,3, in whole or in part, in preparing these into polymers, but with no particular advantage in general. Similarly, -methylstyrene and the various vinyl toluenes can be used in-stead of styrene, if desired.
After polymerization, the rubbery polymer so .,.; i .
3,~ ~ formed is reacted with a dihalogen cross-linking agent to form a synthetic rubber of high green strength, with labile cross-links. The dihalogen cross-linking compound can be added to the ; 20 ~ rubber whilst still present in the polymerization latex, e.g.
during the coagulation process. Alternatively, it can be added ,L: ,- ~
~ to the rubber at a subsequent stage during the finishing process, .
~ after recovery from the latex in the conventional way, e.g. during ,.,.~
. the drying of the rubber or during a milling operation in the ~ process of preparing the rubber for packaging. Alternatively, the halogen compound may be added to the polymer along with other compounding ingredients, e.g. on a rubber mill or in an internal mixer.
Suitable dihalogen compounds for use as cross-linking agents to form the labile cross-links in the compo~ition accord-:
` ~042330 ing to the invention are organic dihalogen compounds, having two halogen groups selected from chlorine, bromine and iodine, located in the molecule in conjugated relationship with an activating group, such as an aromatic nucleus or an ethylen~cally unsaturated group. Examples of suitable halogen containing organo compounds are 1,4-dibromcbutene-2, 1,4-dichlorobutene-2, a, a'di-bromoxylenes, ~,a'dichloroxylenes, liquid dibromopolybuta-diene having bound allylic bromide groups, dibromosorbic ` sorbic acid and alkali metal salts thereof and those dihalogen :~ 10 compounds represented by the general formula:
~ X-CH2 ~ (R) - CH2-X
i. where X represents a halogen group selected from chlorine, bromine, .'~5 and iodine, and R represents a polynuclear aromatic group select-ed from naphthalene, biphenyl, diphenyl ether and diphenyl alkane 3~ wherein the alkane residue has from 1 - 4 carbon atoms, each `::;3 group - CH2-X being linked to a separate aromatic nucleus of he group R, either directly or via the intermediary of a carbonyl group, or R represents an ~-halotoluene group. The aromatic nucleus R may be substituted by other chemical groups, such as methoxy, which do not significantly interfere with the chemical . .; - .
reactions of the- CH2X groups. Specific examples of useful suchdihalogen compounds are the following:
4,4'-Bis(chloromethyl) phenyl ether Cl-CH2- ~ O ~ CH2 Cl :~ 4,4'-Bis(bromomethyl) phenyl ether - Br-CH2- ~ ~ CH2 Br ~^ 2,6-bis(bromomethyl) naphthalene CH2Br ~[~
BrCH2 J~J
4,4'-Bis(bromomethyl) diphenyl methane BrCH2 ~ CH2 ~ CH2Br 4,4'-Bisl~romomethyl) diphenyl BrCH2 ~ CH2Br Tribromo mesitylene CH2Br BrCH2 C 2 ` 2,2',4,4'-tetrakis(bromomethyl) phenyl ether BrCH2 ~ CH2B
- . 10 CH2Br CH2Br 4,4'-Bis(bromoacetyl)diphenyl methane BrCH2- C ~ CH2 ~ C - CH2Br In general, bromo and chloro compounds are pre-. . ., ~ .
~`~ ferred. Iodo compounds are less preferred, partly on account ,~,!, I
-s of cost. Dibro compounds appear to react more quickly and efficiently than corresponding dichloro compounds, in setting up the labile cross-links in the compositions according to the present invention.
It appears that the tertiary amine groups on the ~:.. . .
~ ~ copolymer react with halogen gxoups on the polyhalo compound to ,, form some kind of labile bonds, association or cross-links between the polymer chains. These labile cross-links are responsible for the increase in green strength of the compounds. However, on processing the rubber compounds, e.g. on mixing, milling and extruding, these labile cross-links are broken, perhaps due to the shearing and/or the temperatures encountered in such operations, 80 that the rubber compound based on the copolymer processes as a normal polymer. These labile cross-links appear to be re~ersible, 80 that after processing, the labile crosi-links reform and the high green strength of the compound is recovered. Thus they are quite different in chemical nature and stability from cross-links formed on curing the rubber, e.g. with sulphur and accelerators, which cross-links are chemically much stronger and essentially irreversible.
The amounts of tertiary amine groups in the polymer and the halogen compound reactant, in relation to each other and to the overall amount of polymer, are important. It is desirable to have an approximate chemical equivalence of tertiary amine groups and halogen qroups on the halogen compound. However, one can if desired use a polymer containing a large amount of bound tertiary amine groups, and only use a small amount of .`,. . .
~-~ halogen compound required to give the necessary amount of labile cross-links for improved green strength. By having present a known excess of tertiary amine groups in the polymer, one can then control the desired green strength by adding different amounts of halogen compound. On grounds of economy in the use of tertiary amine monomer and halogen compound, however, large excesses of either material should be avoided. Preferred amounts of halogen compound are such that it contains at least 0.1 and not more than 10 millimoles of halogen groups per 100 grams of polymer, and the most preferred amount of halogen com-pound is that which contains from 2.5 to 7.5 millimoles of halogen groups per 100 grams of polymer.
, .
The a unt of tertiary amine groups in the polymer is relatively small, in the range of from about 0.5 millimoles .
to about 10 millimoles, preferably from about 2.5 to about 7.5 milli les, of tertiary amine groups per 100 grams of polymer.
The minimum i~ dictated by the requirement that satisfactory green strength be achieved in the rubber composition. The maximum is dictated by the necessity of retaining easy factory processability of the compositions, in accordance with normal SBR polymers.
In the case of the most preferred tertiary amine group containing monomer dimethylaminoethyl methacrylate, it is preferred to use from about 0.1 to about 1.2 parts by weight per 100 parts by weight of polymer. Polymers contain-ing such a unts of dimethylaminoethyl methacrylate are suit-ably reacted with from about 0.02 to about 1.5 parts by weight, per 100 parts by weight of polymer, of 1,4-dibromobutene-2, as a specific example of a suitable dihalogen cross-linker.
Examples of rubber compositions for use in the car-~`` cass plies of radial tires according to the present invention are blends of the above high green strength SBR polymers with one or more of another rubber selected from natural rubber ~ conventioral SBR, polybutadiene, and synthetic natural rubber.
:', ~-~ The natural rubber may be present in amounts of from about 75 to about 150 parts by weight per 100 parts by weight of high ' n ~
green strength SBR polymer, in these rubber compositions. The ` other synthetic rubber, such as polybutadiene, conventional SB~ and synthetic natural rubber, may be present in amounts up to 175 parts by weight per 100 parts by weight of high green strength polymer. The compositions may also include hydrocarbon oil and carbon black, in the normal way, and in conventional amounts, commonly encountered in tire carcass rubber compounds.
~; At the time they are used to form the tire cord-rubber ply and - built into the carcass, they are normally compounded with conventional curing systems and compounding ingredients suc~
as zinc oxide, stearic acid, accelerator~, curatives, tacki-fiers, antioxidants and the like, 80 that they are ready to be heated for vulcanization at a later stage in the tire building process, without addition of further ingredients.
It is to be understood that the term "rubber composition" as ~042330 used herein is intended to include elastomeric compositions including standard compounding and curing ingredients, in standard amounts, as are well known in the art.
Thus, the compositions may include fillers such as carbon black, clay, silica, calcium carbonate and titanium dioxide, although carbon black is the filler conventionally used in such compounds. Organic peroxide curing systems are not normally used in such compounds, but are of course appli-cable. The conventional curing systems are the sulphur systems, with a sulphur vulcanization system containing a mixture of about 0.25 - 5 parts per 100 parts rubber of sulphur and up ~;, to about 5 phr of one or more accelerators selected from any of the known accelerator classes. Typical examples of such accelerators include alkyl benzothiazole sulpheramide, a metal ;-~! salt of a dihydrocarbyl dithiocarbamate, morpholinyl benzothia-zole disulphide, dithiomorpholine, 2-mercaptobenzothiazole,
A radial ply pneumatic tire is a tire in which the carcass comprises a number of plies (normally 2 to 4, optional-ly up to 6) of cord reinforced rubber, the cords of which are substantially parallel to one another and extend radially across the tire, generally at about a right angle to the median circumferential line of the tire. An angle of from 75 to 90 of the cords to the median circumferential line is generally considered to characterize a radial ply tire.
The conventional or bias ply pneumatic tire has the cords of ` its carcass plies extending around the tire carcass and on the bias, i.e. at a more acute angle to the median circum-ferential line. Radial tires have a much re flexible car-cass side structure, with much more side wall flex in opera-tion, as compared with bias ply tires. In order to retain necessary road handling ability, radial ply tires must be ~- provided with belts below the tread portion, the belts having strong substantially inextensible fibres extending essentially circumferentially around the tire.
The manufacturing processes generally used for radial tire manufacture put demands upon the physical pro-perties of the rubber compounds used in their carcasses, when in the green or uncured state, which are different from those requiredin bias ply tire manufacture. The carcass of the tire contains a pair of circular beads, normally of steel embedded in rubber, which in the finished tire define the - ~ inner peripheral edges of the tire, and in a tubeless pneuma-tic tire form part of the sealing assembly between the wheel rim and the tire. The tire carcass comprises an inner liner, -- 1 - q~' 10423;~0 which is preferably of substantially air impervious rubber (e.g. bromobutyl), and the plies of cord reinforced rubber extend from bead to bead across the tire. Belts, sidewalls and tread components are applied over the carcass. The radial tire carcass is assembled and shaped with the rubber compounds of the various constituents in the green or uncured state. After this assembly and shaping, the belts, sidewall components and tread components are applied, again in an uncured state, and the assembled tire is cured or vulcanized.
Processes of manufacturing radial tires, whether ~ . .
they are one stage or two stage processes, involve the initial assembling of beads, inner liner and carcass plies as a cylinder of substantially planar wall cross section, the rubber of the carcass plies being in the green state, and the subsequent alteration of the shape of this assembly to a torus.
This alteration of shape involves extension of the green rub-ber compounds at various locations of the carcass by as much as 200 - 300%.
The corresponding change of shape occurs, in the manufacture of a conventional bias ply tire, only when the complete tire has been assembled as a cylinder on a building drum, with the sidewall, tread and any necessary reinforcing belts applied. The assembled tire is transferred to a mold in which it is shaped, the mold is totally closed and the whole subjected to heat and pressure to effect curing.
In contrast, however, the radial tire carcass must be shaped, to reach approximately its final external diameter, before it i8 combined with the tread and belt, and depending on the process, the sidewall portions and hence before it is put into a mold for curing. This is because a radial ply tire has to have incorporated therein reinforcing belts of substan-;
~ - 2 -tially inextensible fibrou~ material, the fibres of which extend circumferentially around the tire, below the tread.
These belts cannot be extended circumferentially, and so they must be applied after shaping the green radial tire car-cas to approximately its final diameter. Thus the green strength of the rubber used in the carcass plies must be sufficient, without the aid of external constraining struc-.
tures such as molds, to withstand stresses applied in the i shaping operation, and under conditions of temperature, etc., ;~
~` 10 normally encauntered in tire manufacturing operations. As noted, this means in practice that the rubber in the green ,, state must be able to withstand elongations of 200% or more.
'~ If the rubber compound used in the plies of the car-~' cass has insufficient green strength to withstand this exten-ir i3 sion and the forces experienced when such extension is caused : `' in commercial manufacture, the cords of the radial plies may i~ ~ not be held in their desired position in the rubber, and may even strike through to the inner liner of the tire or the carcass may thin down or even split. The maintenance of the ~ cords in their preset, predetermined relationship to one another, embedded in the rubber of the carcass plies, through-out the manufacturing process, is important in producing radial tires of high quality.
, .
Conventional synthetic rubbers such as rubbery ~t~ styrene-butadiene copolymers (SBR), synthetic polyisoprene - .~
and polybutadienes are deficient in green strength. For radial tire manufacture, it has been found necessary to use natural rubber, alone or in admixture with synthetic rubbers, so as . .
to obtain a carcass rubber composition of sufficient green strength.
In one of the re commonly used processes for ma~ing ~042330 radial tires, a two stage operation is adopted, in which, in a first stage, the carcass is assembled incorporating the inner liner, beads and radial carcass plies, and shaped to the desired toroidal shape while in the green state. Then in a second stage, the sidewalls, circumferential belts and tread are applied, again in the green state, and then the assembled green tire is heated under pressure in a mold to .
; effect curing. There may be some time lapse between the first and second stages of the operation in which case the first ; 10 stage assembly is usually deflated and then reinflated prior to the second stage. The uncured rubber of the carcass plies ; must be able to withstand being held under stress and in an elongated condition for some period of time without retracting or otherwise deforming to allow movement or strike-through of the cords embedded therein. Conventional synthetic rubber compositions do not have stress - relaxation characteristics in the green state satisfactory to meet these criteria.
In accordance with the present invention, signifi-- cant reduction of these problems of manufacture of radial tire carcasses i8 accomplished by the use, in the rubber-tire cord ., ~
carcass ply sheets of the tire, of green rubber compositions based upon synthetic rubbers which have small numbers of shear and/or heat sensitive labile cross-links, which behave as high green strength rubbers at ordinary temperatures, but as ordinary ,, ~ .
rubbers under the shear and elevated processing temperatures used in a tire factory. An example of such a synthetic rubber ~-~ is a rubbery styrene-butadiene polymer containing a small .. , ; .
~ amount of tertiary amine groups, reacted with a dihalogen com-.. .. .
pound.
Thus according to a first aspect of the present in-., vention, there i~ provided a radial ply pneumatic tire com-:
prising a carcass portion and a belt-tread-sidewall portion;
the carcass portion thereof having an inner rubber liner, a pair or generally circular, substantially inexten-sible beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composition, said cords being mutually parallel and extending at an angle of from about 75 to about 90 to the circumferen-' tial median line of the tire;
.~' 10 the tire carcass rubber composition comprising a ,, '~ high green strength rubber composition comprising a synthetic ~ rubber having labile cross-links, ; the combined carcass and belt-tread-sidewall portions having been vulcanized by the action of heat.
According to another aspect of the present invention, there is provided a process of making a radial ply pneumatic tire having an-inner rubber liner, a pair of generally circu-iar beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composi-;i- tion, which comprises:
~- encasing a plurality of closely spaced, generally ~, mutually parallel tire cord fibres in high green strength tire carcass rubber composition comprising a synthetic rubber having .. labile cross-links so as to form a sheet of rubber-tire cord fabric;
forming a generally cylindrical a9semb1y having an inner layer of tire liner rubber compo8ition, a plurality of outer layers comprised of said sheets of rubber-tire cord ~ 30 fabric, the cords thereof extending radially at an angle of from about 75 to about 90 to the median line of said - _ 5 _ generally cylindrical assembly, and two substantially inex-tensible generally circular beads of uncured rubber covered metal, said beads being located one at each axial end portion of the generally cylindrical assembly;
expanding the central portion of the generally cylin-drical assembly relative to the axial end portions thereof to change the shape of the assembly to toroidal;
adhering thereto the belt, tread and sidewall assemblies;
-- 10 and subsequently curing the assembly by heating.
In the accompanying drawings:
- Figure 1 is a diagrammatic cross sectional illustra-~¦ tion of a first stage in the manufacture of a carcass of a i radial tire according to the invention;
Figure 2-is an illustration similar to Figure 1 showing a subsequent, intermediate step of the manufacture;
.~.
Figure 3 is an illustration similar to Figuresl and ~, 2 showing a third stage in the manufacture.
Figures 1 to 3 show schematically the shaping of a radial ply carcass. The specific illustration shows a carcass having two plies of tire cord fabric. As shown in Figure 1, the carcass is built on a building drum which comprises a cen-tral portion 16 and two outer portions 17 and 18. First, the ii chafers 15 are positioned on the drum - the chafer is compounded - rubber well known in the art which serves to protect the car-. ;., .
~ cass of the finished tire against the chafing action of the : i i ~~i wheel rim. The inner liner 11 is next laid down 90 that the -:, outer edges of the liner are in contact with each chafer at i what will be the toe region of the tire. A first ply of rub-~, 30 ber-tire cord fabric 12 i8 then added, followed by a second ~-~ ply 13, the length of each ply being such that it overlaps the chafer. The bead assembly 14 is next positioned onto the assembly - a bead assembly is well known in the art and com-prises a combination of wires, generally in the form of a multistrand`bead and optionally includes a shaped rubber com-pound adhered to the combination~of wires. The product is thus a planar walled cylinder of various materials.
Figure 2 illustrates an intermediate stage in the ~- process of changing the shape of the cylindrical form of Figure 1 to a toroidal shape of the finished tire. The bead assembly is mechanically held in position relative to the chafer and plies but is moved inwardly so that the centre sec-tion of the carcass assembly ves upward. To accommodate ~, .
this, the central portion of the drum is mechanically reduced n size, in its axial direction. The upward movement of the central portion of the carcass is assisted by inflation which ; may be by directly applying air pressure, or by applying air ,, -f`~ pressure to a membrane forming part of the central portion of .'`1 ' .
the drum or may be by purely mechanical means. This upward movement of the central portion of the carcass is an actual f expansion of this portion, the expansion occurring in the cir-cumferential portion where the tread will subsequently be .
~ ~ applied.` This expansion causes a thinning down of the thick-.....
ness of the rubber and a spreading, in relation one to the . other, of the fibre cords.
-~ - Figure 3 shows a further stage in the expansion and changing to toroidal shape with the bead assemblies being almnst at their final positions and the ply endings having been turned up and around the bead assemblies. On further expansion to - its final dimensions, the belts, tread and sidewalls will be applied.
- During the expansion stage, the carcass requires ~042330 a certain minimum level of strength so that the whole assembly does not rupture or thin down unevenly. On changing from the cylindrical form to the toroidal form the circum-ference of the assembly increases by from about 150% to about 300% in length. The time involved in causing the change in shape is variable depending on the particular manufacturing process involved but may range from as low as about 2 to 3 seconds to as long as 20 to 30 seconds. A polymer having high strength provides the necessary properties to meet these characteristics.
In a radial tire manufacturing process, the uncured tire carcass is maintained in the configuration shown in Figure 3 while applying the remaining components. The green tire carcass is thus being maintained with the uncured rubber compositions of the plies in a stressed condition. There is a natural tendency of rubber compositions to relax when held . ,1 .
- ~ under stress conditions, thereby losing strength. If this happens, the tire cords may move or even strike through the plies, 12, 13, and even through the inner liner 11, thereby ` !
spoiling the assembly.
A ply of the carcass comprises a number of parallel-^~ disposed tire cords encased in an uncured rubber composition.
-s, The cords are each surrounded on all sides by the rubber com-~ position. The cords are generally of steel, rayon, glass, :,, types of nylon, polyester, cotton or the like, and are assembled ~, in a manner well known in the art. The uncured rubber com-pound is applied by calendering onto the cord assembly, to form the ply. The cords may be pretreated with suitable adhesive compositions to improve their adhe8ion to the rubber composi-tion.
According to the present invention, the uncured ~ 104Z330 rubber compound which is used in the rubber-tire cord carcass plies is based at least in part upon a high green strength synthetic rubber having labile cross-links. Such rubber com-pounds have suitable characteristics in the green state to be able to withstand the deformations and extensions, the exten-sion at the required rate, and the stress-relaxation demands, experienced in commercial radial tire manufacture, at the tem-peratures generally encountered during such manufacture which are normally from about 15C to about 40C, but may even be as high as 50C. An example of a synthetic rubber upon which these rubber compounds can be based is a rubbery SBR polymer containing small amounts of tertiary amine groups in the , polymer chains, the polymer having been reacted with a dihalo-;- ~ gen compound capable of reacting with the tertiary amine ,. ~ , groups in the polymer.
The SBR polymer used in such a composition is preferably a rubbery styrene-butadiene polymer containing from about 60 to about 85% by weight, most preferably from about 70 to 82% by weight, of butadiene and from about 40 to about 15% by weight, most preferably from about 30 to about 18% by weight, of styrene, ~-` and containing from about 0.5 millimoles to about 10 millimoles, ;~ preferably from about 0.75 millimoles to about 7.5 millimoles, and most preferably from about 2.5 to about 7.5 millimDles, of ~ound tertiary amine groups per 100 grams of polymer. The tertiary .
,~ amine groups are suitably introduced by copolymerizing with the styrene and butadiene a suitable amount of a tertiary amine group containing monomer, the tertiary amine groups of which are sub-stantially unaffected by the polymerization.
Preferred suitable tertiary amine group containing monomers sre dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate. Dimethylaminoethyl methacrylate i8 especially preferred. This monomer readily copolymerizes with butadiene and styrene in conventional emulsion polymerization recipes and systems commonly used for making SBR polymers for synthetic rubber applications. It has a copolymerization reactivity similar to that of the copolymerizing monomers in such a system. A
rubbery polymer is obtained with ~ertiary amine groups distributed along and among the polymer chains.
Of course, other similar C4 - C6 conjugated diolefinic hydrocarbons such as isoprene, piperylene and 2,3-dimethyl-butadiene-1,3 can be substituted for the commoner and cheaper butadiene-1,3, in whole or in part, in preparing these into polymers, but with no particular advantage in general. Similarly, -methylstyrene and the various vinyl toluenes can be used in-stead of styrene, if desired.
After polymerization, the rubbery polymer so .,.; i .
3,~ ~ formed is reacted with a dihalogen cross-linking agent to form a synthetic rubber of high green strength, with labile cross-links. The dihalogen cross-linking compound can be added to the ; 20 ~ rubber whilst still present in the polymerization latex, e.g.
during the coagulation process. Alternatively, it can be added ,L: ,- ~
~ to the rubber at a subsequent stage during the finishing process, .
~ after recovery from the latex in the conventional way, e.g. during ,.,.~
. the drying of the rubber or during a milling operation in the ~ process of preparing the rubber for packaging. Alternatively, the halogen compound may be added to the polymer along with other compounding ingredients, e.g. on a rubber mill or in an internal mixer.
Suitable dihalogen compounds for use as cross-linking agents to form the labile cross-links in the compo~ition accord-:
` ~042330 ing to the invention are organic dihalogen compounds, having two halogen groups selected from chlorine, bromine and iodine, located in the molecule in conjugated relationship with an activating group, such as an aromatic nucleus or an ethylen~cally unsaturated group. Examples of suitable halogen containing organo compounds are 1,4-dibromcbutene-2, 1,4-dichlorobutene-2, a, a'di-bromoxylenes, ~,a'dichloroxylenes, liquid dibromopolybuta-diene having bound allylic bromide groups, dibromosorbic ` sorbic acid and alkali metal salts thereof and those dihalogen :~ 10 compounds represented by the general formula:
~ X-CH2 ~ (R) - CH2-X
i. where X represents a halogen group selected from chlorine, bromine, .'~5 and iodine, and R represents a polynuclear aromatic group select-ed from naphthalene, biphenyl, diphenyl ether and diphenyl alkane 3~ wherein the alkane residue has from 1 - 4 carbon atoms, each `::;3 group - CH2-X being linked to a separate aromatic nucleus of he group R, either directly or via the intermediary of a carbonyl group, or R represents an ~-halotoluene group. The aromatic nucleus R may be substituted by other chemical groups, such as methoxy, which do not significantly interfere with the chemical . .; - .
reactions of the- CH2X groups. Specific examples of useful suchdihalogen compounds are the following:
4,4'-Bis(chloromethyl) phenyl ether Cl-CH2- ~ O ~ CH2 Cl :~ 4,4'-Bis(bromomethyl) phenyl ether - Br-CH2- ~ ~ CH2 Br ~^ 2,6-bis(bromomethyl) naphthalene CH2Br ~[~
BrCH2 J~J
4,4'-Bis(bromomethyl) diphenyl methane BrCH2 ~ CH2 ~ CH2Br 4,4'-Bisl~romomethyl) diphenyl BrCH2 ~ CH2Br Tribromo mesitylene CH2Br BrCH2 C 2 ` 2,2',4,4'-tetrakis(bromomethyl) phenyl ether BrCH2 ~ CH2B
- . 10 CH2Br CH2Br 4,4'-Bis(bromoacetyl)diphenyl methane BrCH2- C ~ CH2 ~ C - CH2Br In general, bromo and chloro compounds are pre-. . ., ~ .
~`~ ferred. Iodo compounds are less preferred, partly on account ,~,!, I
-s of cost. Dibro compounds appear to react more quickly and efficiently than corresponding dichloro compounds, in setting up the labile cross-links in the compositions according to the present invention.
It appears that the tertiary amine groups on the ~:.. . .
~ ~ copolymer react with halogen gxoups on the polyhalo compound to ,, form some kind of labile bonds, association or cross-links between the polymer chains. These labile cross-links are responsible for the increase in green strength of the compounds. However, on processing the rubber compounds, e.g. on mixing, milling and extruding, these labile cross-links are broken, perhaps due to the shearing and/or the temperatures encountered in such operations, 80 that the rubber compound based on the copolymer processes as a normal polymer. These labile cross-links appear to be re~ersible, 80 that after processing, the labile crosi-links reform and the high green strength of the compound is recovered. Thus they are quite different in chemical nature and stability from cross-links formed on curing the rubber, e.g. with sulphur and accelerators, which cross-links are chemically much stronger and essentially irreversible.
The amounts of tertiary amine groups in the polymer and the halogen compound reactant, in relation to each other and to the overall amount of polymer, are important. It is desirable to have an approximate chemical equivalence of tertiary amine groups and halogen qroups on the halogen compound. However, one can if desired use a polymer containing a large amount of bound tertiary amine groups, and only use a small amount of .`,. . .
~-~ halogen compound required to give the necessary amount of labile cross-links for improved green strength. By having present a known excess of tertiary amine groups in the polymer, one can then control the desired green strength by adding different amounts of halogen compound. On grounds of economy in the use of tertiary amine monomer and halogen compound, however, large excesses of either material should be avoided. Preferred amounts of halogen compound are such that it contains at least 0.1 and not more than 10 millimoles of halogen groups per 100 grams of polymer, and the most preferred amount of halogen com-pound is that which contains from 2.5 to 7.5 millimoles of halogen groups per 100 grams of polymer.
, .
The a unt of tertiary amine groups in the polymer is relatively small, in the range of from about 0.5 millimoles .
to about 10 millimoles, preferably from about 2.5 to about 7.5 milli les, of tertiary amine groups per 100 grams of polymer.
The minimum i~ dictated by the requirement that satisfactory green strength be achieved in the rubber composition. The maximum is dictated by the necessity of retaining easy factory processability of the compositions, in accordance with normal SBR polymers.
In the case of the most preferred tertiary amine group containing monomer dimethylaminoethyl methacrylate, it is preferred to use from about 0.1 to about 1.2 parts by weight per 100 parts by weight of polymer. Polymers contain-ing such a unts of dimethylaminoethyl methacrylate are suit-ably reacted with from about 0.02 to about 1.5 parts by weight, per 100 parts by weight of polymer, of 1,4-dibromobutene-2, as a specific example of a suitable dihalogen cross-linker.
Examples of rubber compositions for use in the car-~`` cass plies of radial tires according to the present invention are blends of the above high green strength SBR polymers with one or more of another rubber selected from natural rubber ~ conventioral SBR, polybutadiene, and synthetic natural rubber.
:', ~-~ The natural rubber may be present in amounts of from about 75 to about 150 parts by weight per 100 parts by weight of high ' n ~
green strength SBR polymer, in these rubber compositions. The ` other synthetic rubber, such as polybutadiene, conventional SB~ and synthetic natural rubber, may be present in amounts up to 175 parts by weight per 100 parts by weight of high green strength polymer. The compositions may also include hydrocarbon oil and carbon black, in the normal way, and in conventional amounts, commonly encountered in tire carcass rubber compounds.
~; At the time they are used to form the tire cord-rubber ply and - built into the carcass, they are normally compounded with conventional curing systems and compounding ingredients suc~
as zinc oxide, stearic acid, accelerator~, curatives, tacki-fiers, antioxidants and the like, 80 that they are ready to be heated for vulcanization at a later stage in the tire building process, without addition of further ingredients.
It is to be understood that the term "rubber composition" as ~042330 used herein is intended to include elastomeric compositions including standard compounding and curing ingredients, in standard amounts, as are well known in the art.
Thus, the compositions may include fillers such as carbon black, clay, silica, calcium carbonate and titanium dioxide, although carbon black is the filler conventionally used in such compounds. Organic peroxide curing systems are not normally used in such compounds, but are of course appli-cable. The conventional curing systems are the sulphur systems, with a sulphur vulcanization system containing a mixture of about 0.25 - 5 parts per 100 parts rubber of sulphur and up ~;, to about 5 phr of one or more accelerators selected from any of the known accelerator classes. Typical examples of such accelerators include alkyl benzothiazole sulpheramide, a metal ;-~! salt of a dihydrocarbyl dithiocarbamate, morpholinyl benzothia-zole disulphide, dithiomorpholine, 2-mercaptobenzothiazole,
2-mercaptoimidazoline etc. The amounts of filler may vary up ~- to 150 parts, and hydrocarbon oil up to 100 parts, per 100 parts of total rubber. The well known compounding and vulcani-zation technology may be used for these polymers.
Mixing may be on a mill or in a Banbury mixer, or in two or more stages using a Banbury followed by mill mixing ~-of the curatives. The components added to the mill or mixer may also include the halogen compound for cross-linking. After thorough mixing in the normal way, the rubber compound can be applied to the tire cords to form the carcass plies, as pre-viously described.
The invention is further illustrated in the following specific examples.
Example 1 A rubbery styrene-butadiene-dimethylaminoethyl :~ ~042330 methacrylate polymer was prepared by emulsion copolymerization ~ using a redox initiator system in the normal way for preparing ;~ SBR rubber, to obtain a polymer containing about 23 weight %
styrene, 75 weight % butadiene and 0.8 weight:% dimethylamino-~` ethyl methacrylate. After coagulation and recovery in the normal way, during which 37.5 phr of oil was added to the polymer, it was reacted in a Banbury mixer with 0.2 phr dibromo-butene-2, to give a rubber of high green strength containing .
~` ;~ labile cross-links. Prior to reaction with the dibromobutene-2, the oil extended polymer had a Mooney ~ML-4 at 100C) of 40.
After reaction with the dibromobutene-2, the resulting rubber ;gave Mooney values (ML-4 at 100C) of between 75 and 90, but nevertheless processed at elevated temperatures and under con-dition~ of high shear, e.g. in the Banbury at 280 - 320F
about 140-160C) in a similar manner to a 40 Mooney rubber.
$his high green strength rubber was used in the subsequent examples, for~preparing rubber compositions and vulcanizates thereof, for testing purposes. It behaved on processing as though it were a 40 Mooney rubber not a 75-90 Mooney rubber, indicating its suitability for use in applying to tire cords, after compounding, in the normal way to prepare a rubber-tire cor~ fabric ply for a radial tire, by calendaring with the tire cords.
Example 2 A series of rubber compositions was prepared using the high green strength rubber of Example 1, and tested for physical properties in the green state. Table 1 show8 the rubber hydrocarbon~ u~ed in each compooition, in part8 by weight. Each compo8ition was prepared by making a ma8terbatch by Banbury mixing at 300F (about 150-C), with the following compounding ingredients (in part8 by weight):
.,~ , ~ ,, s ~04Z330 Carbon black 50.0 zinc oxide 5.0 Stearic acid 1.5 Hydrocarbon resin tackifier 2.0 Antioxidant 2.0 Bonding resin 3.0 . The bonding resing has the effect of improving adhesion of the composition to the tire cords. In each case, ~ the butadiene-styrene rubber, whether standard SBR or the :~ 10 polymer of Example 1, contained 37.5 parts per hundred rubber .~ of mineral oil. Then the masterbatches so formed were ~- further mixed with additional ingredients, including curatives, - on a mill at about 100F (about 40C), to give green rubber compositions suitable for making radial tire carcass plies.
To a quantity of masterbatch containing 100 parts by weight of rubber hydrocarbons, the following ingredients were added : on the mill (in parts by weight):
Sulphur 3.0 Sulphenamide type accelerator 0.9 - 20 Diphenyl guanidine accelerator 0.2 ; Bonding compound 1.0 . The compositions so formed were tested for green : strength, after various periods of time after mixing, by pulling on an Instron tester according to the standard test - procedures. The results are given in Table I.
~042330 O ~ U~ - I` U~ ~D , ~ _ ~D ~ ~ ~ ~
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In U~ ~ ,, o oo o ,u~ t` , 0 W
u~ t` ~1~r N ~ ~r(~ . ~ ~ ~ _ 11~
~ ~ o ~ r~ o o ~ ~7 o _ .
~ `
. ~ O ~C U~ O O
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u~ r-. O~ Co I~ O
1~ U'), er Ir) . O
r ~ ~ ~
.
U~
_I O ~i O . O 1_ 0 ~9 E~ . .
O In ~ ~ O ~ _~
O~ O ~ 0 . COO ~ . CO~ _~ _ ~ ~ .C
., ~ ~: ~ S:
. ~ In a~ .o In ~ ~ ~
~ ~ ~ s o~
~ ~ a) o ~
~ I h ~ I ~ al U~ ~ ~ ~ dQ S
~ S~ X ~ ~ X-- ~
~ ~ J~
z a) )~ ~ ~ ~, S~
~ ~ co ~ ~ a~ ~ ~~ o C: n a~
O ~3 ~ 1~ ~ rl h 1:: ha~ )~
1 ~ ~ t~ O.CS~,Y ~ O ~_ o a~ la _ .,~~ _ ~
o ~ X ~ .~ ~ s I X ~ o~ ~s X ~ o~
. ~ Z 0 ~4 ~0 ~o . ~ .
:` . ~r ~ ~D O O ~O ~
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: ~ ~ N O N ~ N
., 1~ ~ I O O ~ O
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1' u~ ~ v~ ,1 O J~ N O O O CO ~D O
a ~ ~ _ o G ~ ~ C,) o ,~ .
`J~-~ ~ ~
~ _ ~1 ~-r~ _ ~ ~ ~ a~ 2 ~ 2 K~
It will be noted from the above results that the control composition 0, despite the presence therein of 50 parts by weight of natural rubber, has a very low green strength. Not only is its maximum green strength very low, but also this maximum is reached at low elongations - 100~
or less. Thus the composition shows a typical stress-strain curve of an ordinary synthetic rubber composition - a positive, steep initial slope to a low value of elongation at maximum tensile strength, followed by a gradual negative slope as elongation is increased. By the time an elongation of 300%
is reached, an elongation which as previously noted is ; likely to be encountered by the rubber composition in radial tire carcass manufacture, the rubber composition is beyond its maximum tensile strength, and has very little strength indeed. ~he risk of failure in the use of such a composition in radial tire carcass ply manufacture is apparent, in view of its lack of green strength at such elongation.
; In contrast, composition 1, based upon high green strength, SBR, but in all other respects an identical composition to control 0, has re than twice the maximum green strength, and more than three times the green strength at 300% elongation, as compared with the control. This composition is clearly much superior for use in radial tire carcass manufacture.
The results with compositions 2,4 and 6 demonstrate that a substantial portion of the natural rubber in the -~ control can be replaced with polybutadiene, provided high green strenth SBR with labile cross-links, is present, and a significant improvement in green strength of the composi-~' ~ - 20 -tion still obtained.
, The results with compositions 3 and 5 show that essentially similar effects can be obtained by replacing some of the natural rubber with a regular SBR. Further tests ~`` show that at 50C, the compositions according to this inven-~' tion retain considerable green strength.
t Example 3 Portions of compositions 0 (control), 1, 2, and 3, 4 and 5 were vulcanized by heating at 145C for 25 minutes, I 10 and the vulcanizates subjected to a series of standard physical tests to determine their properties. The results are given in Table 2.
t , .-~-` ', ., , :-`
;'' .
~ 30 ~' 10423;~0 _ O _ __ O N ~ N O
11~ __ N N O _ _ ___i O N N
~1 O ~ In O . . .
~r ~D CS~ N ~-1l l ~1 --1 ~1 ~1 ~1 '; ' _ _ ___ _ _~ __ 1` O X C~ G~ cn I_ ~r N
U~ 00 ~1 CO l l . . .
~ ~-1 ~ _1 ~1 _1 ~1 ~ _ _ _~ _ O
o o _I ~r a~ 1~ Il~ ~) N
., N _ ~= N O ------r---- ~
N a~ O ~ O N ~1 0 ~ CO ~1 _I N el' ~1 CO _i ~) O O
_ _ _ _ _ -- N ----~ ~ O ~) O Ir~ N ~D 1~1 N O CO
:~ ~
., ~ 0~
E i _ N N E~ _ O
~ Z s Y~ ~ ~ yU ~ ~
O ~ rl ~ ~ ~ _ S O
~ ~ ~ ~ ~ ~ .~ 0 ~ 1:: O dP O ~ ra0 ~
u ~ o o a ~ o ~042330 The figures indicate that the vulcanizates are acceptable for use in tire carcass plies, and are in almost all respects the approximate equivalent of the control vul-canizate. As noted in connection with Example 2, the control 0 and the composition 1 differ only in the use of standard SBR and the high green strength SBR polymer of Example 1, and the two vulcanizates are essentially the same in physical properties. The vulcanizates of compositions 2 to 5 merely show variations in properties to be expected from the changes in rubber hydrocarbon composition. Effectively, the advantage of higher green strength demonstrated in Table 1 has been achieved without significant effect on the vulcanizate properties.
Radial ply tires constructed using carcass-tire cord plies containing rubber compositions of the type shown in Example 2 and containing the high green strength SBR
of Example 1 were found to exhibit good properties during the construction and the advantages due to the use of the high green strength polymers were readily apparent, in the better handling, great dimensional stability and reduced cord strike through.
-~042330 ExamPLe 4 Using the green strength SBR of Example 1, rubber compounds were prepared following the recipe and procedure of Example 2 except that the ratio of the rubber components was Natural rubber 60 parts by weight Oil extended SBR 41. 25 ~
Polybutadiene 10 ~ tl ~- , - A control compound was also prepared in which the oil extended ~ - SBR was a regularly available polymer.
.~ 10 The green strengths of these compounds were determined with the results shown in Table 3.
.
` , ' . '. .
;, , . .
~, ~ 20 . ~
, . `.- ~ I
., .
' ' ; 30 ..
, 'Tabl`e 3 ~ Control Green Strength Green strength properties ''Comp'o'und '' '' SBR ' ' After 2 hours aging:
Max. green strength Ckg/cm2) 2.1 2.8 Elongation at max. green strength (%) 70 375 Green strength at 300%
elongation (kg/cm2) 1.6 2.7 10After 24 hours aging:
Max. green strength (kg/cm2~ 2.3 2.9 Elongation at max. green strength (%) 70 400 Green strength at 3Q0%
elongation (kg/cm2) 2.2 2.8 After 72 hours aging*:
Max. green strength (kg/cm2) 3.7(1.4) 3.6(1.6) Elongation at max. green strength (%)' 650(50) 300(100) - 20Green strength at 300%
- elongation Ckg/cm2) 2.7(0.6) 3.6(1.6) *Note: Figures in brackets are results obtained for test measurements made at 50C instead of 22C.
The results show that, even at the high natural rubber content of these compounds, the green strength of the control compound is unsatisfactory except after aging for 72 hours, whereas the'compound of the present invention exhibits satisfactory green strength after aging even for only 2 hours.
Examp'le 5 Using the rubbery styrene-butadiene-dimethylamino-ethyl methacrylate polymer of Example 1, a green strength polymer was prepared by the'addition, during the coagulation, of the dihalogen compounds shown in Table 4. The amount of 4,4'-bis(bromomethyl) diphenyl ether was 0.2 parts by weight per 100 parts by weight of polymer and the amount of 4,4'-bis (bromomethyl) diphenyl methane was 0.19 parts by weight per 100 parts by weight of polymer, Each polymer also contained 37.5 parts by weight per 100 parts by weight of polymer of a hydrocarbon oil. These green strength polymers were com-pounded according to the recipe and procedure of Example 2 and tested for green strength after the aging times shown in .
; Table 4.
:
' Ta~'le 4 Di~alogen Compound 4t4'-bis- 4,4'-bis-(bromomethyl)- (bromomethyl)-diphenyl diphenyl ''eth'er' '' methane Green Strength - -After 2 hours aging:
Max ~reen strength ~kg7cmZ) 2.8 3.2 Elongation at max.
green strength (%) 200 250 ~ Green strength at 300%
-` elongation Ckg/cm2) 2.7 3.1 , After 24 hours aging:
- - Max. green strength (kg/cmZ) 3.9 3.8 ,~ Elongation at max.
green strength (%) 700 700 ' 20 Green strength at 2%
,,' ~ elongation Ckg/cm ) 3.3 3.4 ,,, ::
-~, After 72 hours aging:
Max. ~reen strength g/cm2) 4.3 4.1 ~` Elongation at max.
green strength (%) 700 700 , , ~
' Green strength at 300%
elongation (kg/cm2) 3,7 3 7 ~, ' The results in TabLe 4 show good development of green strength for these compounds. Further stocks of these compounds were vulcanized and the vulcanizates showed good properties making them suitable for use in radial tires.
' 10 ,.
i'
Mixing may be on a mill or in a Banbury mixer, or in two or more stages using a Banbury followed by mill mixing ~-of the curatives. The components added to the mill or mixer may also include the halogen compound for cross-linking. After thorough mixing in the normal way, the rubber compound can be applied to the tire cords to form the carcass plies, as pre-viously described.
The invention is further illustrated in the following specific examples.
Example 1 A rubbery styrene-butadiene-dimethylaminoethyl :~ ~042330 methacrylate polymer was prepared by emulsion copolymerization ~ using a redox initiator system in the normal way for preparing ;~ SBR rubber, to obtain a polymer containing about 23 weight %
styrene, 75 weight % butadiene and 0.8 weight:% dimethylamino-~` ethyl methacrylate. After coagulation and recovery in the normal way, during which 37.5 phr of oil was added to the polymer, it was reacted in a Banbury mixer with 0.2 phr dibromo-butene-2, to give a rubber of high green strength containing .
~` ;~ labile cross-links. Prior to reaction with the dibromobutene-2, the oil extended polymer had a Mooney ~ML-4 at 100C) of 40.
After reaction with the dibromobutene-2, the resulting rubber ;gave Mooney values (ML-4 at 100C) of between 75 and 90, but nevertheless processed at elevated temperatures and under con-dition~ of high shear, e.g. in the Banbury at 280 - 320F
about 140-160C) in a similar manner to a 40 Mooney rubber.
$his high green strength rubber was used in the subsequent examples, for~preparing rubber compositions and vulcanizates thereof, for testing purposes. It behaved on processing as though it were a 40 Mooney rubber not a 75-90 Mooney rubber, indicating its suitability for use in applying to tire cords, after compounding, in the normal way to prepare a rubber-tire cor~ fabric ply for a radial tire, by calendaring with the tire cords.
Example 2 A series of rubber compositions was prepared using the high green strength rubber of Example 1, and tested for physical properties in the green state. Table 1 show8 the rubber hydrocarbon~ u~ed in each compooition, in part8 by weight. Each compo8ition was prepared by making a ma8terbatch by Banbury mixing at 300F (about 150-C), with the following compounding ingredients (in part8 by weight):
.,~ , ~ ,, s ~04Z330 Carbon black 50.0 zinc oxide 5.0 Stearic acid 1.5 Hydrocarbon resin tackifier 2.0 Antioxidant 2.0 Bonding resin 3.0 . The bonding resing has the effect of improving adhesion of the composition to the tire cords. In each case, ~ the butadiene-styrene rubber, whether standard SBR or the :~ 10 polymer of Example 1, contained 37.5 parts per hundred rubber .~ of mineral oil. Then the masterbatches so formed were ~- further mixed with additional ingredients, including curatives, - on a mill at about 100F (about 40C), to give green rubber compositions suitable for making radial tire carcass plies.
To a quantity of masterbatch containing 100 parts by weight of rubber hydrocarbons, the following ingredients were added : on the mill (in parts by weight):
Sulphur 3.0 Sulphenamide type accelerator 0.9 - 20 Diphenyl guanidine accelerator 0.2 ; Bonding compound 1.0 . The compositions so formed were tested for green : strength, after various periods of time after mixing, by pulling on an Instron tester according to the standard test - procedures. The results are given in Table I.
~042330 O ~ U~ - I` U~ ~D , ~ _ ~D ~ ~ ~ ~
, . .
In U~ ~ ,, o oo o ,u~ t` , 0 W
u~ t` ~1~r N ~ ~r(~ . ~ ~ ~ _ 11~
~ ~ o ~ r~ o o ~ ~7 o _ .
~ `
. ~ O ~C U~ O O
~~1 0 O O -e~ 1 ~ r _ . .
u~ r-. O~ Co I~ O
1~ U'), er Ir) . O
r ~ ~ ~
.
U~
_I O ~i O . O 1_ 0 ~9 E~ . .
O In ~ ~ O ~ _~
O~ O ~ 0 . COO ~ . CO~ _~ _ ~ ~ .C
., ~ ~: ~ S:
. ~ In a~ .o In ~ ~ ~
~ ~ ~ s o~
~ ~ a) o ~
~ I h ~ I ~ al U~ ~ ~ ~ dQ S
~ S~ X ~ ~ X-- ~
~ ~ J~
z a) )~ ~ ~ ~, S~
~ ~ co ~ ~ a~ ~ ~~ o C: n a~
O ~3 ~ 1~ ~ rl h 1:: ha~ )~
1 ~ ~ t~ O.CS~,Y ~ O ~_ o a~ la _ .,~~ _ ~
o ~ X ~ .~ ~ s I X ~ o~ ~s X ~ o~
. ~ Z 0 ~4 ~0 ~o . ~ .
:` . ~r ~ ~D O O ~O ~
~', .' ~n ~
: ~ ~ N O N ~ N
., 1~ ~ I O O ~ O
J~ 11~ ~D~ ~
_~ ~ V~ O O N D
1' u~ ~ v~ ,1 O J~ N O O O CO ~D O
a ~ ~ _ o G ~ ~ C,) o ,~ .
`J~-~ ~ ~
~ _ ~1 ~-r~ _ ~ ~ ~ a~ 2 ~ 2 K~
It will be noted from the above results that the control composition 0, despite the presence therein of 50 parts by weight of natural rubber, has a very low green strength. Not only is its maximum green strength very low, but also this maximum is reached at low elongations - 100~
or less. Thus the composition shows a typical stress-strain curve of an ordinary synthetic rubber composition - a positive, steep initial slope to a low value of elongation at maximum tensile strength, followed by a gradual negative slope as elongation is increased. By the time an elongation of 300%
is reached, an elongation which as previously noted is ; likely to be encountered by the rubber composition in radial tire carcass manufacture, the rubber composition is beyond its maximum tensile strength, and has very little strength indeed. ~he risk of failure in the use of such a composition in radial tire carcass ply manufacture is apparent, in view of its lack of green strength at such elongation.
; In contrast, composition 1, based upon high green strength, SBR, but in all other respects an identical composition to control 0, has re than twice the maximum green strength, and more than three times the green strength at 300% elongation, as compared with the control. This composition is clearly much superior for use in radial tire carcass manufacture.
The results with compositions 2,4 and 6 demonstrate that a substantial portion of the natural rubber in the -~ control can be replaced with polybutadiene, provided high green strenth SBR with labile cross-links, is present, and a significant improvement in green strength of the composi-~' ~ - 20 -tion still obtained.
, The results with compositions 3 and 5 show that essentially similar effects can be obtained by replacing some of the natural rubber with a regular SBR. Further tests ~`` show that at 50C, the compositions according to this inven-~' tion retain considerable green strength.
t Example 3 Portions of compositions 0 (control), 1, 2, and 3, 4 and 5 were vulcanized by heating at 145C for 25 minutes, I 10 and the vulcanizates subjected to a series of standard physical tests to determine their properties. The results are given in Table 2.
t , .-~-` ', ., , :-`
;'' .
~ 30 ~' 10423;~0 _ O _ __ O N ~ N O
11~ __ N N O _ _ ___i O N N
~1 O ~ In O . . .
~r ~D CS~ N ~-1l l ~1 --1 ~1 ~1 ~1 '; ' _ _ ___ _ _~ __ 1` O X C~ G~ cn I_ ~r N
U~ 00 ~1 CO l l . . .
~ ~-1 ~ _1 ~1 _1 ~1 ~ _ _ _~ _ O
o o _I ~r a~ 1~ Il~ ~) N
., N _ ~= N O ------r---- ~
N a~ O ~ O N ~1 0 ~ CO ~1 _I N el' ~1 CO _i ~) O O
_ _ _ _ _ -- N ----~ ~ O ~) O Ir~ N ~D 1~1 N O CO
:~ ~
., ~ 0~
E i _ N N E~ _ O
~ Z s Y~ ~ ~ yU ~ ~
O ~ rl ~ ~ ~ _ S O
~ ~ ~ ~ ~ ~ .~ 0 ~ 1:: O dP O ~ ra0 ~
u ~ o o a ~ o ~042330 The figures indicate that the vulcanizates are acceptable for use in tire carcass plies, and are in almost all respects the approximate equivalent of the control vul-canizate. As noted in connection with Example 2, the control 0 and the composition 1 differ only in the use of standard SBR and the high green strength SBR polymer of Example 1, and the two vulcanizates are essentially the same in physical properties. The vulcanizates of compositions 2 to 5 merely show variations in properties to be expected from the changes in rubber hydrocarbon composition. Effectively, the advantage of higher green strength demonstrated in Table 1 has been achieved without significant effect on the vulcanizate properties.
Radial ply tires constructed using carcass-tire cord plies containing rubber compositions of the type shown in Example 2 and containing the high green strength SBR
of Example 1 were found to exhibit good properties during the construction and the advantages due to the use of the high green strength polymers were readily apparent, in the better handling, great dimensional stability and reduced cord strike through.
-~042330 ExamPLe 4 Using the green strength SBR of Example 1, rubber compounds were prepared following the recipe and procedure of Example 2 except that the ratio of the rubber components was Natural rubber 60 parts by weight Oil extended SBR 41. 25 ~
Polybutadiene 10 ~ tl ~- , - A control compound was also prepared in which the oil extended ~ - SBR was a regularly available polymer.
.~ 10 The green strengths of these compounds were determined with the results shown in Table 3.
.
` , ' . '. .
;, , . .
~, ~ 20 . ~
, . `.- ~ I
., .
' ' ; 30 ..
, 'Tabl`e 3 ~ Control Green Strength Green strength properties ''Comp'o'und '' '' SBR ' ' After 2 hours aging:
Max. green strength Ckg/cm2) 2.1 2.8 Elongation at max. green strength (%) 70 375 Green strength at 300%
elongation (kg/cm2) 1.6 2.7 10After 24 hours aging:
Max. green strength (kg/cm2~ 2.3 2.9 Elongation at max. green strength (%) 70 400 Green strength at 3Q0%
elongation (kg/cm2) 2.2 2.8 After 72 hours aging*:
Max. green strength (kg/cm2) 3.7(1.4) 3.6(1.6) Elongation at max. green strength (%)' 650(50) 300(100) - 20Green strength at 300%
- elongation Ckg/cm2) 2.7(0.6) 3.6(1.6) *Note: Figures in brackets are results obtained for test measurements made at 50C instead of 22C.
The results show that, even at the high natural rubber content of these compounds, the green strength of the control compound is unsatisfactory except after aging for 72 hours, whereas the'compound of the present invention exhibits satisfactory green strength after aging even for only 2 hours.
Examp'le 5 Using the rubbery styrene-butadiene-dimethylamino-ethyl methacrylate polymer of Example 1, a green strength polymer was prepared by the'addition, during the coagulation, of the dihalogen compounds shown in Table 4. The amount of 4,4'-bis(bromomethyl) diphenyl ether was 0.2 parts by weight per 100 parts by weight of polymer and the amount of 4,4'-bis (bromomethyl) diphenyl methane was 0.19 parts by weight per 100 parts by weight of polymer, Each polymer also contained 37.5 parts by weight per 100 parts by weight of polymer of a hydrocarbon oil. These green strength polymers were com-pounded according to the recipe and procedure of Example 2 and tested for green strength after the aging times shown in .
; Table 4.
:
' Ta~'le 4 Di~alogen Compound 4t4'-bis- 4,4'-bis-(bromomethyl)- (bromomethyl)-diphenyl diphenyl ''eth'er' '' methane Green Strength - -After 2 hours aging:
Max ~reen strength ~kg7cmZ) 2.8 3.2 Elongation at max.
green strength (%) 200 250 ~ Green strength at 300%
-` elongation Ckg/cm2) 2.7 3.1 , After 24 hours aging:
- - Max. green strength (kg/cmZ) 3.9 3.8 ,~ Elongation at max.
green strength (%) 700 700 ' 20 Green strength at 2%
,,' ~ elongation Ckg/cm ) 3.3 3.4 ,,, ::
-~, After 72 hours aging:
Max. ~reen strength g/cm2) 4.3 4.1 ~` Elongation at max.
green strength (%) 700 700 , , ~
' Green strength at 300%
elongation (kg/cm2) 3,7 3 7 ~, ' The results in TabLe 4 show good development of green strength for these compounds. Further stocks of these compounds were vulcanized and the vulcanizates showed good properties making them suitable for use in radial tires.
' 10 ,.
i'
Claims (19)
1. A radial ply pneumatic tire comprising a carcass portion and a belt-tread-sidewall portion;
the carcass portion thereof having an inner rubber liner, a pair of generally circular substantially inextensible beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composition, said cords being mutually parallel and extending at an angle of from about 75° to about 90° to the circumferential median line of the tire;
the tire carcass rubber composition comprising a high green strength rubber composition comprising a synthetic rubber having labile cross-links, the combined carcass and belt-tread-sidewall portions having been vulcanized by the action of heat.
the carcass portion thereof having an inner rubber liner, a pair of generally circular substantially inextensible beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composition, said cords being mutually parallel and extending at an angle of from about 75° to about 90° to the circumferential median line of the tire;
the tire carcass rubber composition comprising a high green strength rubber composition comprising a synthetic rubber having labile cross-links, the combined carcass and belt-tread-sidewall portions having been vulcanized by the action of heat.
2. The radial tire of claim 1, wherein the high green strength rubber composition comprises the reaction pro-duct of a rubbery polymer of a C6 - C8 conjugated diolefinic hydrocarbon and at least one monomer selected from styrene, .alpha.-methylstyrene and vinyl toluenes, and having incorporated therein a small amount of tertiary amine groups, with a di-halogen compound to form quaternary ammonium salts therewith as labile cross-links.
3. The radial tire of claim 1 wherein the high green strength rubber composition comprises the reaction product of a rubbery polymer of from about 60 - 85 parts by weight bound butadiene and 40 - 15 parts by weight bound styrene, and having incorporated therein from 0.1 - 10 millimoles of tertiary amine groups per 100 grams of interpolymer, with a dihalogen compound to form quaternary ammonium salts therewith as labile cross-links.
4. The radial tire of claim 3 wherein the interpolymer is a polymer of butadiene, styrene and a tertiary amine group containing monomer selected from dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate.
5. The radial tire of claim 4 wherein the tertiary amine group containing monomer is dimethylaminoethyl meth-acrylate.
6. The radial tire of claim 4 wherein the dihalogen compound is selected from dibromobutene-2, dichlorobutene-2, .alpha.,.alpha.'-dibromoxylenes, .alpha.,.alpha.'-dichloroxylenes, liquid dibramopolybutadiene having bound allylic bromide groups, dibromosorbic acid and alkali metal salts thereof, and dihalo compounds represented by the general formula:
X-CH2 - (R) - CH2-X
wherein X represents chloro, bromo or iodo, and R represents either a polynuclear aromatic group selected from biphenyl, diphenylether, diphenyl thioether, diphenyl alkane in which the alkane residue has 1 - 4 carbon atoms, each group CH2-X
being linked, either directly or through the intermediary of a carbonyl group, to a separate nucleus of the aromatic group, or R represents an .alpha.-halotoluene group.
X-CH2 - (R) - CH2-X
wherein X represents chloro, bromo or iodo, and R represents either a polynuclear aromatic group selected from biphenyl, diphenylether, diphenyl thioether, diphenyl alkane in which the alkane residue has 1 - 4 carbon atoms, each group CH2-X
being linked, either directly or through the intermediary of a carbonyl group, to a separate nucleus of the aromatic group, or R represents an .alpha.-halotoluene group.
7. The radial tire of claim 3, claim 4 or claim 5 wherein the dihalogen compound is selected from dibromobutene-2, .alpha.,.alpha.'-dibromo-p-xylene, 4,4'-bis(chloromethyl)-phenyl ether, 4,4'-bis(bromomethyl)phenyl ether, 2,6-bis (bromomethyl) naphthalene, 4,4'-bis(bromomethyl)diphenyl methane, 4,4'-bis(bromomethyl)diphenyl, tribromomesitylene, 4,4'-bis (bromoacetyl)diphenyl methane and 2,2',4,4'-tetrakis (bromo-methyl)phenyl ether.
8. The radial tire of claim 3, claim 4 or claim 5 wherein the dihalogen compound is 1,4-dibromobutene-2.
9. The radial tire of claim 6 wherein the tire carcass rubber composition comprises the prodùct formed by vulcanizing to form permanent chemical cross-links a high green strength rubber composition comprising said synthetic rubber having labile cross-links, in admixture with one or more other rubbersselected from natural rubber, rubbery styrene-butadiene polymers, polybutadiene and poiyisoprene.
10. The radial tire of claim 9 wherein the high green strength rubber composition comprises from about 75 to about lS0 parts by weight of natural rubber and up to 175 parts of rubber selected from rubbery styrene-butadiene copolymers, polybutadiene and polyisoprene, per 100 parts by weight of said synthetic rubber having labile cross-links, the synthetic rubber comprising the reaction product of a rubbery polymer of from about 60 - 85 parts by weight bound butadiene, from about 40 - 15 parts by weight bound styrene and having incorporated therein from 0.1 - 10 millimoles of tertiary amine groups per 100 grams of interpolymer, with a dihalogen compound.
11. The radial tire of claim 10 wherein the rubbery polymer is a polymer of butadiene, styrene and dimethylamino-ethyl methacrylate, and the dihalogen compound is 1,4-dibromo-butene-2.
12. A process for making a radial ply pneumatic tire having an inner rubber liner, a pair of generally circular beads generally defining the inner circular aperture of the tire, and a plurality of plies of rubber-tire cord fabric comprising tire cords encased in a tire carcass rubber composition, which comprises:
encasing a plurality of closely spaced, generally mutually parallel tire cord fibres in a high green strength tire carcass rubber composition comprising a synthetic rubber having labile cross-links so as to form a sheet of rubber-tire cord fabric;
forming a generally cylindrical assembly having an inner layer of uncured tire liner rubber composition, a plurality of outer layers comprised of said sheets of rubber-tire cord fabric, the cords thereof extending radially at an angle of from about 75° to about 90° to the median line of said generally cylindrical assembly, and two substantially inextensible generally circular beads of uncured rubber covered metal, said beads being located one at each axial end portion of the generally cylindrical assembly;
expanding the central portion of the generally cylindrical assembly relative to the axial end portions thereof to change the shape of the assembly from cylindrical to toroidal;
adhering thereto the belt, tread and sidewall assemblies;
and subsequently curing the assembly by heating.
encasing a plurality of closely spaced, generally mutually parallel tire cord fibres in a high green strength tire carcass rubber composition comprising a synthetic rubber having labile cross-links so as to form a sheet of rubber-tire cord fabric;
forming a generally cylindrical assembly having an inner layer of uncured tire liner rubber composition, a plurality of outer layers comprised of said sheets of rubber-tire cord fabric, the cords thereof extending radially at an angle of from about 75° to about 90° to the median line of said generally cylindrical assembly, and two substantially inextensible generally circular beads of uncured rubber covered metal, said beads being located one at each axial end portion of the generally cylindrical assembly;
expanding the central portion of the generally cylindrical assembly relative to the axial end portions thereof to change the shape of the assembly from cylindrical to toroidal;
adhering thereto the belt, tread and sidewall assemblies;
and subsequently curing the assembly by heating.
13. The process of claim 12 wherein the high green strength tire carcass rubber composition comprises the reaction product of a rubbery polymer of from about 60 - 85 parts by weight bound butadiene and 40 - 15 parts by weight bound styrene, and having incorporated therein from 0.1 - 10 millimoles of tertiary amine groups per 100 grams of polymer, with a dihalogen compound to form quaternary ammonium salts therewith as labile cross-links.
14. The process of claim 13 wherein the polymer is a terpolymer of butadiene, styrene and dimethylaminoethyl methacrylate.
15. The process of claim 13 wherein the dihalogen com-pound is selected from dibromobutene-2, .alpha.,.alpha.-dibromo-p-xylene, 4,4'-bis(chloromethyl)-phenyl ether, 4,4'-bis(bromomethyl) phenyl ether, 2,6-bis(bromomethyl) naphthalene, 4,4'-bis (bromomethyl) diphenyl methane, 4,4'-bis(bromomethyl) diphenyl, tribromomesitylene, 4,4'-bis(bromoacetyl) diphenyl methane and 2,2',4,4'-tetrakis(bromomethyl) phenyl ether.
16. The process of claim 14 wherein the dihalogen compound is 1,4-dibromobutene-2.
17. The process of claim 13 wherein the tire cord fibres are encased in a high green strength tire carcass rubber composition comprising said reaction product of rub-bery polymer and dihalogen compound in admixture with natural rubber.
18. The process of claim 17 wherein the high green strength of rubber composition comprises from about 75 to about 200 parts by weight of natural rubber, per 100 parts by weight of said synthetic rubber having non permanent heat labile cross-links.
19. The process of claim 18 wherein the high green strength rubber composition additionally includes up to 35 parts by weight of another synthetic hydrocarbon rubber selected from polybutadiene and butadiene-styrene rubbery copolymers.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA243,410A CA1042330A (en) | 1976-01-13 | 1976-01-13 | Radial ply pneumatic tires and process for their manufacture |
| FR7608926A FR2345304A1 (en) | 1976-01-13 | 1976-03-26 | PNEUMATIC BANDAGE WITH A RADIAL CARCASS AND ITS REALIZATION PROCESS |
| GB12215/76A GB1515594A (en) | 1976-01-13 | 1976-03-26 | Radial ply pneumatic tyres and process for their manufacture |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA243,410A CA1042330A (en) | 1976-01-13 | 1976-01-13 | Radial ply pneumatic tires and process for their manufacture |
| FR7608926A FR2345304A1 (en) | 1976-01-13 | 1976-03-26 | PNEUMATIC BANDAGE WITH A RADIAL CARCASS AND ITS REALIZATION PROCESS |
| GB12215/76A GB1515594A (en) | 1976-01-13 | 1976-03-26 | Radial ply pneumatic tyres and process for their manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042330A true CA1042330A (en) | 1978-11-14 |
Family
ID=27164274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,410A Expired CA1042330A (en) | 1976-01-13 | 1976-01-13 | Radial ply pneumatic tires and process for their manufacture |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1042330A (en) |
| FR (1) | FR2345304A1 (en) |
| GB (1) | GB1515594A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57208233A (en) * | 1981-06-18 | 1982-12-21 | Mitsubishi Heavy Ind Ltd | Method and apparatus for manufacturing radial tire |
| DE3636783A1 (en) * | 1986-10-29 | 1988-05-05 | Uniroyal Englebert Gmbh | VEHICLE TIRES |
| IT1227655B (en) * | 1987-12-09 | 1991-04-23 | Uniroyal Englebert Gmbh | TIRE FOR VEHICLES. |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1053832A (en) * | 1973-11-08 | 1979-05-01 | Polysar Limited | Polymeric antioxidants |
| CA1014295A (en) * | 1973-11-08 | 1977-07-19 | John R. Dunn | Amine modified remoldable rubbers |
| CA1014296A (en) * | 1973-11-08 | 1977-07-19 | Ernest J. Buckler | Amine modified polymers |
| US3915907A (en) * | 1974-12-16 | 1975-10-28 | Goodyear Tire & Rubber | Chlorothio-sulfonamide-modified rubbery terpolymers and their blends |
-
1976
- 1976-01-13 CA CA243,410A patent/CA1042330A/en not_active Expired
- 1976-03-26 FR FR7608926A patent/FR2345304A1/en active Granted
- 1976-03-26 GB GB12215/76A patent/GB1515594A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2345304B1 (en) | 1981-02-27 |
| GB1515594A (en) | 1978-06-28 |
| FR2345304A1 (en) | 1977-10-21 |
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