DE1729558A1 - Process and single-layer material for renewing the tread of pneumatic tire covers - Google Patents

Description

D3 -ING. H. ri ^

DH »MN © .S.8TAE01 * APIL 27, 1967

MONKS 5

MOLLERSTR. 31

M 7067

Description of the patent application

from BANDAG INCORPORATED, Muscatine, Jova, V. St. A.

concerning

"Process and single-ply material for renewing the running surface of air-raid ceilings ¹¹ .

Priority: 01/26/1967 - V.St.A.

The invention relates to a method for renewing the Tread of a tire cover with a pre-vulcanized tread. By cold vulcanization.

In particular, the inventive method is based on the Simplification of the cold aging process through the use of a single strip of binding material based on rubber, which is both a vulcanizer and a vulcanization accelerator in one

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It contains an initially stabilized state and means that the temperature of a cold vulcanizing process cannot be vulcanized at a very low level. The process essentially consists in placing the binding strip between a prepared tire crown and a pre-vulcanized strip - the tire being pressed against the binding strip and (about 300 °?) over1 the Kaltvulkanieation herbeiBuführen heating to about 150 ⁰ O.

The invention is an improvement over the tread renewal methods disclosed in the United States patents 2 x 976 x 910 and 3 x 136 x 673, and the invention is an improvement over the method of FIG United States Patent 3,236,709 in that the process steps described therein are achieved through the use of a single Simplified strip of binding material according to the invention can be.

They aforementioned patents relate to Xaltvulkanisierverfahren by welohe a pre-vulcanized! Aufstreifen with a tire casing hei a relatively low temperature to about 150 ⁰ C (300 ⁰ T) is adhesively bonded · This KaltvuUcanisierrerfahren have over conventional Heifivulkanislerverfahren in which a tire building, an unvulcanized tire and a binding agent at relatively high pressures and temperatures

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exposed to several benefits. I'm an advantage in that the tread can be pre-vulcanized at a higher pressure and a higher temperature than can be used during Seuprofilieren, whereby a very tough, wear-resistant running strip is obtained. A unvulcanized tread can become vulcanized a tire cover cannot be subjected to very high pressure without the tire being permanently deformed ^ j or warps. The barrel strip therefore does not develop the toughness that is expected from pre-vulcanization high pressure of, for example, 21 - 70 kg / cm (300 to 1000 psi) can be developed. In addition, the increased temperatures that occur during the warm soling process have an effect be used, in a weakening as well as in damage to the previously or previously vulcanized tire cover the end.

The two cold vulcanization methods used in the aforementioned patents essentially consist of binders made of two separate rubber-based materials, which were used until immediately before the initiation of the vnIfranisierverfhrens are served separately from each other. One of the materials contains a vulcanizer while the other material contains a vulcanization accelerator. During execution the method according to the aforementioned USA patent 2,976,910 becomes the crown of the tire cover after buffing

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first covered with a gummy solution containing either the vulcanizer or the vulcanization accelerator and certain other ingredients to give body to achieve density. Then will the second material, a strip of cushion gum material, applied to the coated crown, which second material contains the vulcanizer or the accelerator, depending on which of the two in ' the rubber-like solution was contained · A pre-vulcanized barrel strip is placed on both of them, and a bridge is applied and cold vulcanization initiated.

In the method of the aforementioned US Pat. No. 3,136,673, the separate rubber-based materials, one containing a vulcanizer and the other containing an accelerator, are provided in the form of two separate binding strips of rigid, flexible cushion rubber material. One of these strips is first coated on the precured tread to obtain a layer structure, which is stored until use · The Profilierunge- or Besohlungsverfahren is done by the other binding strip crown between a tire and a suitable length of the layer structure is applied, the layer structure is pressed against the interposed strip and heated.

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These previous methods have proven to be very successful, although they are not completely without difficulties.For example, with the gummy solution plus single strip technique it is sometimes difficult to apply the gummy solution evenly, so that the bond is uneven unless expensive application devices are used. With the two-strip technique, it was found that the ski structure made of μ binding strips and tread strips has a relatively short shelf life, so that the layer structures have to be prepared when the order is received or at the time of soling.

The present invention, i.e. the application of a single ply tie coat, avoids these difficulties and brings with it several other advantages that are facilitated in the Tire soling and reducing the cost of such work. One of the main advantages " consists in the fact that pre-vulcanized strips have a long shelf life in comparison to the useful life of about one year for the layer structure made of running tires and single-ply, one-component binding tape the aforementioned U.S. Patent 3,136,673. With regard to the one-year service life of the layered It is for the manufacturer and the tread renovator not economical to store large stocks,

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since the ale longer one year bearing layer structures require re-treatment to the one-component binder that its potency has lost to remove. However, if the single-ply bicomponent binding tape is applied to the tread at the time of the soling, the process becomes more flexible as there is no storage time. In this context, it must be taken into account that the tire soling is carried out by a large number of independent small companies, most of which are not equipped for an after-treatment of treads, in which the binding layers are removed, which are overdone and therefore of questionable quality.

Another major advantage of using the invention Single-strip two-component binder is in the reduction of the time required and in the set-up, necessary to produce the single strip is compared to the several compositions previously used.

A particular advantage of the invention consists in the composition of the single-layer binding layer and in its compatibility with a pre-vulcanized barrel strip and with a tire casing. In recent years, PKV and truck tires with tread and tread underlay loops were made from synthetic rubbers of high molecular weight . These rubbers are used

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by adding large amounts of oil, especially larger amounts aromatic oils, made processable and the carbon black content is proportionally higher in order to maintain the reinforcement and to improve the tread wear and the generation of heat to belittle. These changes first came and are present in styrene-butadiene rubbers with other tire polymers such as cis-4-polybutadiene and Cis-l-3-polyisoprene provided. Tread renewal rubbers also contain these oil extenders.

The high oil content of these types of rubber poses a problem for the tread renewal industry, as the oils tend to migrate out of the tire and / or the tread, thereby adversely affecting the pestibility properties of the sole binder and reducing the vulcanization and adhesion properties. It was found that this is in the aforementioned layer structures of tread and one-component bonding material etc.

is the case and contributes to the 3 strength properties and deteriorate the vulcanization ability. A hike of extra oil from a tire can happen during a cold soling process, which multiplies the problem. In the pail of a hot soling process the applied higher temperatures intensify the migration, so that in some cases a

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drive a satisfactory tread renewal or - Soling cannot be achieved.

However, by preferred binding strips according to the invention an oil migration from a tire or tread of absorb high oil content during cold soling or tolerate without sacrificing important strength properties get lost. Although it has a high oil content on its own, its composition allows it to contain more oil absorb. In addition, its use with low-oil rubbers is satisfactory. Further the migration of oil during the actual soling process is kept to a minimum as the The presence of both the vulcanizer and the accelerator enables the vulcanization to be carried out quickly once the activation temperatures are reached. If the vulcanizing components are contained in separate mixtures that are brought together at the time of the soling, a delay occurs while the Both components migrate into the adjacent layers, and the oil migrates from the tire and / or tread can also be done during the delay.

To carry out the process, the binding agent mass is in the form of thin sheets of rubber cushion material produced, the width of which corresponds to the width of the

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shaped treads correspond with which the tracks to be used later. If a tread renewal "or. Soling process is to be performed, a length that is equal to the circumference of the tire carcass is located between the crown of the tire and a similar length of the vorvulkcui ^ fourth tread. The assembly thus obtained is subjected to radial pressure to bring the strips into intimate contact with the ™

Tire crown and press together and for vulcanizing and adhesive bonding. Heat supplied. Temperatures up to about 15o ° C (about 300 ⁰ P) are suitable, with a preferred range between 90.5 and 93t3 ⁰ C (195-200 ⁰ F).

The method described above can be performed using the various method steps and apparatus like in the aforementioned U.S. Patents 2,976,910, 3,136,673 and 3,236,709 are described so that this will be given here, no further details. Further, it should be mentioned that the method using the same type of precure tread as described in the referenced patents, provides that Laufetreifen of a rubber material which bie at about 157 ° 165.5 ⁰ C (about 315 ° to 330 ⁰ F) under a pressure of 21-70 kg / cm (300-1000 pai), preferably higher «la

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42 kg / cm ² (600 psi) has been fully vulcanized.

The barrel can vary in composition change that it works with the tire material as well as with the Synthetic rubber content and oil content is compatible.

The approach to the binding tape used in practicing the invention is for tires and treads high oil content as follows:

Components parts by weight

unvulcanized natural rubber.

(or synthetic natural rubber) 85-10

unvulcanized synthetic rubber 15 ± 10 Zinc oxide 5-10 Anti-aging agents, e.g.
Phenyl-p-naphthylamine 2-3 Sulfur or other vulcanizer 1-3 Accelerator (active under about
93 ⁰ O to vulcanization
below about 15o °) 1-3 Carbon black λ 25-35 Stretches} Ie (highly aromatic oils) 15-25 Resins 5-10

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One of the main goals of synthetic rubber, gas black, of the extending oils and the resins consists in creating one satisfactory adhesion to tire tread compound compositions, the synthetic rubbers and mixtures of synthetic rubbers, which are stretched with large amounts of oil are. Synthetic rubber of one for use

en
in the tire "known / type, for example styrene butadiene rubber, Ci s-4-polybutadienkautsch.uk and cis-l-4-polyisoprene rubber, because of the compatibility and to reduce the M

Reversal tendency (devulcanization) used by natural rubber when it is bent under high heat conditions. Carbon black is chosen because of the high percentage of extinguishing oil, both for the oil in the binding strip itself and for the oil that migrates from a running strip with a high oil content. The oil content of the binding belt is set sufficiently high to the migration of oil-strip from a barrel to reduce higher oil content, thereby preventing deterioration of the strength properties and performance to J. In addition, the chemical nature of the oils used should be the same as that of the oils used in the tread and / or in the tire or should be compatible with these oils.

When liquid oils are in large quantities in a rubber compound are used, they are difficult to incorporate.

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In addition, the liquid oils migrate from layers of high Oil content to layers of lower oil content until the content in both layers is equal to each other. as Resins are used to replace part of the oil. These are solids and do not migrate. The oil content in the binding layer is therefore made up of both liquid oil and composed of solid resin. You used amount of the latter is about equal to the additional oil that is in the Binding layer made of an adjacent material with a higher Oil content could migrate and decrease the amount of oil that could migrate from the binding layer to an adjacent layer of lower oil content. The ones used here special resins are Koresin (an alkylphenoacetylene resin)

fr '■

and Durez 19 900 (a phenolic resin) and are used in a 1: 2 ratio for the best possible performance used for reducing oil migration problems as well as for increased stickiness.

Generally the composition contains about two parts sulfur per 100 parts rubber and about two parts accelerator to 100 parts of rubber. .

If the tie layer is made at the factory, it will be the components are intimately mixed with one another and in one

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conventional system brought in the form of webs. The finished web may have a thickness of about 0.38 mm (about 0.015 "), although actual thickness is not critical and will be determined by tire performance. Usually the Sheets cut into long strips with a width equal to the width of the La- u. ** ^., Tire with which it is used should be. A corresponding strip of a protective material, such as impregnated paper, cellophane, Polyethylene or the like., Is placed on the binding tape and both are wound up in the form of a roll, the can be stored until use. Optionally, the webs can be produced in such a way that a Layer, which only contains the vulcanizer (sulfur) and is half the thickness of the layer, is used while the other half contains the accelerator ingredients to Achieve a higher shelf life, although this results in a slightly lower vulcanization rate leads. In any case, no special ingredients are required to prevent premature vulcanization.

The single-layer bonding layer can be stored at 40 ⁰ C (104 ⁰ F) for a considerable period of time, be without premature vulcanization is to be feared, even though a storage temperature of 21 ⁰ O (70 ° P) is preferred. This property is achieved by the fact that minimum times and

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-Temperature are used for mixing the vulcanizing ingredients into the rubber and small batches are used at a certain low heat when the tie layer is formed into a sheet form for use. After the web forming the Bindeschlcht need to room temperature, 21 ° immediately - cooled 27 ⁰ C (7O ⁰ P 80 ⁰ P), stored in a cool room and transported in trucks or containers which the rubber below about 40 ⁰ C (about 104 ° P). For example, the mixing requires separate incorporation of accelerators and vulcanizer (sulfur) by! Temperatures below 74 ⁰ C (165 ⁰ F) and subsequently, the immediate cooling of the rubber to room temperature. The web production temperatures are kept below 74 ⁰ C (165 ⁰ P). The one to be brought into web form

Rubber is used in quantities no greater than 13 »5 kg

• π- ■
(30 lbs) for every 5 minutes of forming time, followed by

the web is loosely wound up and immediately cooled.

The binding layer can also be produced in retreading workshops and applied directly to the tire or the tread. This creates the need avoided for the aforementioned protective coating.

The accelerator preferably contains approximately equal proportions of the zinc salt of ethylphenyldithiooarbanic acid and the Cyclohexylethylamine salt of this acid. Know it however

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also other "known accelerators that cause rapid vulcanization." "Result at low temperature and have a long shelf life, such as cyclohexylethylamine used will.

One embodiment of an arrangement for implementation the method according to the invention is shown in the accompanying drawing, namely show:

Pig. 1 is an exploded sectional view showing a precured tread and a single-ply, two-component binding tape in the assembly for assembly into a tire casing shows;

Pig. Figure 2 is a perspective view, partly in section, of a preferred form of apparatus for use for connecting the in Pig. I illustrated parts with each other and ™

Pig. Figure 3 is a partial view in section of part of that shown in Pig. 2 shown device.

In Pig. 1 are the relative positions of a tire cover 10, a running strip 12 and a single-layer two-component

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Binding strip 14 is shown prior to performing the binding process. The tire cover IO has the usual Innenkar box 16, which is protected by an outer side layer 18 made of rubber and a worn or incomplete tread or crown part 20, which is roughened along the road surface 22 on the circumference to accommodate the strip 12 of pre-vulcanized and profiled renewal or soling material has been prepared. Both the tread underlay part and the tread strip 12 are formed from a mixture of natural rubber and synthetic rubber with a high oil content. The run roaming en 12 has been preformed by vulcanization in a suitable press under a pressure of about 42 kg / cm ² (about 600 psi) at about 160 ⁰ C (about 320 ° P).

The binding process takes place essentially in such a way that suitable lengths of the tread 12 and the binding tape 14 are cut, the strips are wrapped around the tire surface 22 in such a way that the binding relieves 14 are located between the surface 22 and the tread 12 , whereupon the assembly is subjected to radial pressure and sufficient heat to vulcanize the binding strip 14.

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A preferred manner in which radial pressure and heat can be applied is shown in FIG Fig. 2 and 3 shown, from which it follows that the arrangement is first on the outside with an airtight, annular and flexible hood or sheath 24 made of plastic, rubber or a similar elastic Material is included. The shell 24 has two flexible side wall parts 26, which extend over the lateral Edges of the barrel strip extend beyond and enclose the tire shoulders 29 and are also in elastic contact with these * The sheath 24 is provided with an outlet 30 for discharging the Air. The arrangement obtained in this way is applied to a rim 32, the two circumferential flanges 34 and has suitable means 36 so that the tire cover 10 can be inflated.

As evidenced by Pig. 3 results, the parts of the elastic cover 24 which extend over the tire shoulders 29 are in sealing contact with the shoulders 29 and the flanges 34. The space between the tire cover 10 and the cover 24 is therefore against a connection with the Effectively sealed inside the ceiling. As a result , the space mentioned is in connection with the environment only through the outlet 30. The seal between the

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Cover 24 and the tire cover 10 can of course also be on other way than in fig. 2 and 3, can be produced.

The arrangement of the tire cover 10, the binding strip 14, the tire 12, rim 32 and shell 24 are then placed in an autoclave or pressure chamber 38, respectively. The chamber 38 is provided with an outlet 40 which is in communication with the outside air. Within of the chamber 38, the outlet 40 is connected to the outlet 30 of the casing 24 by a line 42. Through the wall the chamber 38 also has an inlet line 44 which is connected to the inlet 36 of the rim 32. That from its end of the line 44 is connected to a not shown Pressure source connected to inflate the tire cover 10 during its treatment in the chamber 38.

After the assembly has been placed in the chamber 38. is, the latter is pressurized and heated to a somewhat elevated temperature of preferably about 60 ° C to about 150 ° C (about 140 ° P to about 300 ° P) in such a way that a heated medium is introduced into the chamber 38 will. This has the consequence that the Blndestreifen 14 is vulcanized with the tire surface 22 and with the Laufetreifen 12, is connected tightly adhered whereby the latter with the Tire 10th Simultaneously with

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Upon pressurization of the chamber 38, the tire cover is inflated via the inlet 36. The pressure in the Tire cover 10 should exceed the pressure in chamber 38 where a pressure difference in the range of 1.05 - 3 »50 kg / cm (15 to 50 psi) is preferred. During the printing

in the chamber 38 should be at least 3 »50 kg / cm (50 psi)

a chamber pressure of 6 kg / cm (85 psi) is used

ο
a pressure of 8 kg / cm (115 psi) in the tire cover 10 is preferred.

Optionally, the tire cover 10 can be partially inflated before the treatment in the chamber 38 and subsequently inflated to the desired pressure in chamber 38 during treatment. In any case it is essential that the pressure in the tire cover 10 is the pressure in the chamber 38 when the binding strip 14 is vulcanized exceeds.

Since the space between the tire cover 10 and the elastic cover 24 via the outlet 30, the conduit 42 and the Chamber outlet 40 is in free connection with the outside air, only the outside air pressure prevails in this room. The pressure in the chamber 38, which is higher than the outside air pressure is, presses on the surface exposed to it the tire surface 10 of the tread 12 and the intermediate

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lying binding strip 14. Air trapped in the binding strip 14 between the tire cover 10 and the running strip 12 is therefore expelled and discharged through the outlet 30 to the outside air. In addition, the pressure of the chamber 38 acting through the elastic cover 24 presses the inner surface of the tread 12 radially against the circumferential surface 22 of the tire cover 10, so that a uniform surface vulcanization of the binding strip 14 between them is achieved. The pressure pressing on the strip 12 against the tire cover 10 is equal to the chamber pressure minus the exhaust air pressure that exists in the space between the cover 24 and the tire cover. It follows "loht ^daee no deformation or shrinkage of the cover 10 when the tread 12 Aufvulkanieteren takes place on this, since the pressure within the tire constantly exceeds the pressure of the surrounding chamber. It should be mentioned here that the embodiment described is particularly advantageous for the soling of tires, such as nylon-reinforced tires, in which there is a risk of shrinkage when exposed to the somewhat increased temperature during vulcanization.

The pressure exertion in the pressure chamber 38 can either be air, water or another suitable medium,

Ϊ: 'ti-

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_οΐ_

that can be heated can be used. The tire cover 10 can with air, water or with another Medium that can be heated, be filled regardless of the particular medium that is used to exert pressure is used in the chamber 38, i.e. water, air or other medium. It should be mentioned that the above specified pressure values are only preferred pressure values and that other pressures, including pressures that are essential higher than those within the aforementioned ranges, the only limitation being consists in taking into account the costs and the complicated structure of a suitable facility.

As a particular example of the composition of the binding tape 14, which is suitable for a tire cover made of natural rubber and Ois-4-polybutadiene rubber, is the given the following approach:

Components parts by weight

Natural rubber 85.00

C is-4- polybutadiene rubber: ( in the form

of 100 parts of Cie-4 polybutadiene

plus 37.5 parts of highly aromatic oil) 20.63

Carbon black 28.00

Zinc oxide 3.00

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Age Rite Resin D (an anti-aging agent) 1.00

Thermoflex A (an anti-aging agent) I ₁ OO

Stearic acid 2.00

Durez 19900 resin (a phenolic resin) 2.00 Köreβin (an alkylphenol acetylene resin) 1.00

Methylzymate (an accelerator) 0.13

2-mercaptobenzothiazole. 0.60

Sulfur (vulcanizer) 2.00

PhJrlch (a highly aromatic β oil) 6.00

B.It.E, (an anti-aging agent) 1.00

Medium pine tar 3 »00

A-32 (an accelerator) 0.70

157.08

It should be mentioned here, however, that the proportions and identities of the components, in particular the rubber and the oil, can be changed so that the binding strip 14 is compatible with the composition of the tire and the tread with regard to the rubber and oil content. As mentioned, the resin content is important in achieving a composition which resists oil migration between the various layers.

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The invention is not limited to that in the foregoing Description given details "limited.

Claims;

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Claims (3)

Eat en tana ρ r tt eh et 1. A method for cold binding of a pre-vulcanized running tire with the tread of a tire cover, characterized in that a monocable of a rubber-based binding material is arranged between the running tire and the tread, which contains both a vulcanizer and an accelerator in stabilized form, and then the bonding material web by heating at an elevated temperature of less than about 15O ⁰ C (about 30O ⁰ F) is heated to initiate the vulcanization reaction. 2. Procedure for renewing the road surface of a Rubber tire by placing a preformed tread made of vulcanized rubber, characterized in that between the road surface of the Tire and the preformed running strelfen a single one preformed strip of Kieeengummler-Blndematerlal (cushion gum material) of essentially more uniform Thickness is arranged, which strip contains unvulcanized rubber, rubber stretching oils, a Vulcanizer and a vulcanization accelerator, -25-1098 both of which are in a stabilized state and are suitable for vulcanizing the aforementioned vulcanized rubber at temperatures below about 150 ° C (about 30O ⁰ F), and the tire sole arrangement obtained is exposed to an external pressure which is at least approximately equal to the normal tire pressure at a The temperature is below about 150 ⁰ O in order to achieve a uniform bond between the road surface and the aforementioned preformed tread strip. 3. The method according to claim 1 or 2, characterized in that the tire and the tread are both natural (or synthetic-natural) and synthetic rubber and contains the binder mentioned 75 - 95 parts by weight of natural rubber (or synthetic natural rubber) 5 - 25 parts by weight of synthetic rubber, 15-25 parts by weight of extending oils, 1-3 parts by weight of vulcanizer, 1-3 parts by weight of accelerator and 5-10 parts by weight of oil migration inhibitor in the form of a resin with specific compatibility and adhesion to tire compounds heavily extended with oil. For company BANMG INCCStPORATSD I. H "" Ctt, MPC-WiO. H. KHk 109832/0476