Pneumatic tyres for a vehicle

The invention relates to a pneumatic vehicle tire in radial design with a tire inner side facing the inner layer, a carcass ply with running in the radial direction of reinforcing materials made of steel cord and an inserted between the carcass ply and the inner layer Squeegeelage.

In pneumatic tires for heavy duty vehicles, such as trucks, buses or the like, the phenomenon can occur during the life of the tire, the steel cord of the carcass ply on the tire inside to shine through. In order to prevent this effect or at least reduce, it is customary to introduce a so-called Squeegeelage between the carcass ply and the inner layer. Since the Squeegeelage can come in the carcass ply in contact with the steel cords, it is the usual way from a rubber composition prepared, which is the topping rubber of the carcass ply very similar, especially to both mixtures meet the high requirements for steel cord and durability. It is therefore common and even necessary to use in the rubber mixture for the Squeegeelage natural rubber or a high proportion of natural rubber as well as introducing an appropriate bonding agent system for steel cord. These measures make the production of Squeegeelagenmischung very expensive. This is particularly disadvantageous especially when the Squeegeelagendicke must be very high in the heated tires, for example, on the order of 1 mm to 2 mm in order to prevent it from becoming the carcass.

A pneumatic vehicle tire of the initially mentioned type is known from <patcit id="pcit0001" dnum="EP1145871B"><text>EP-B 1,145,871</text></patcit> known. In this document, it is paramount to improve the adhesive properties of the carcass ply Squeegeelage. The Squeegeelage is therefore constructed such that it comprises at least one abutting the carcass ply rubber composition, which contains a basic inorganic filler.

The invention has the object of being able to produce the Squeegeelage much cheaper than before in a vehicle pneumatic tire, a good steel cord, the necessary durability and the effect of preventing a translucence of the carcass or decrease, should be ensured.

The set object is achieved according to the invention that the Squeegeelage is running two shifts, said the carcass facing outer layer is based on an adhesive mixture and is designed and optimized for good steel cord and durability and is based the rubber composition for the inner layer of rubber mix, which have little or no mixing constituents that characterize an adhesive mixture containing, wherein the outer layer of the Squeegeelage as adhesion promoter one or more of the additives resorcinol, cobalt salt or HMMM, each in an amount of from 0.5 phr to 3.0 phr, and ZnO in contains a proportion of at least 4 phr.

In particular, the thickness of the outer layer of the Squeegeelage between 0.1 mm and 1 mm.

Therefore, an inventively executed pneumatic vehicle tire comprising a two-layer Squeegeelage in which facing the said carcass ply and is made at this applied outer layer of a rubber mixture, which ensures a good steel cord, and the required durability, whereby this layer can be made substantially thinner than the inner layer , The inner layer is significantly less expensive to produce than the outer layer and ensures that the carcass can not shine through.

In a preferred embodiment of the invention the thickness of the outer layer of the Squeegeelage is less than the thickness of the inner layer. Especially at high Squeegeelagendicken can this measure provides an appreciable cost reduction achieved.

The outer layer of Squeegeelage contains as coupling agent a, but in particular several or all of the additives resorcinol, cobalt salt or HMMM, each in an amount of from 0.5 phr to 3.0 phr, and ZnO in an amount of at least 4 phr. The outer layer is therefore preferably carried out as a typical adhesive layer.

For the mechanical properties of the outer layer, it is furthermore advantageous if this contains silica in an amount of from 3.0 phr to 10 phr.

The outer layer further contains in the rubber component is at least 60 phr of natural rubber, whereas the inner layer in the rubber component contains at most 60 phr natural rubber. In this case, the inner layer in the rubber component one or more synthetic rubber (s) such as BR and / or contain SBR, whereby exclusively synthetic rubber can be used in this layer. This measure results in a significant cost reduction, without adversely affecting the function of the inner layer.

Further features, advantages and details of the invention will be described in detail with reference to the drawing, which schematically represents an embodiment of the invention. The sole Figure,<figref idrefs="f0001">Fig. 1</figref>, Shows an axial sectional view - in the circumferential direction and thus transversely to the extension of the carcass - through a cut arranged in the tire Squeegeelage.

The invention is concerned with an embodiment of a Squeegeelage 1 in a vehicle pneumatic tire for heavy vehicles, lorries, buses and the like. The existing rubber material Squeegeelage 1 is located, as it<figref idrefs="f0001">Fig. 1</figref> shows, between the tire interior facing inner layer 2 and the carcass ply 3. The carcass ply 3 is made in the radial direction and extending substantially in the radial direction carcass cords 5 of steel and the Karkassgummierung 6, in which the carcass cords 5 are embedded. The Squeegeelage 1 is two-layer structure and has a standing with the inner layer 2 contacting the inner layer 1a and a standing with the carcass ply 3 in contact outer layer 1b. The voltage applied to the carcass ply 3 outer layer 1b has a substantially constant thickness of from 0.1 mm to 1 mm, in particular from 0.5 mm to 1.0 mm, on which is also substantially constant thickness of the inner layer 1a is between 0.5 mm and 1.5 mm. The outer layer 1b underlying rubber mixture is carried out such that it adheres well to the carcass ply 3 and has good durability. In particular, it is important that the rubber mixture for the outer layer 1b has a good steel cord, for the case in which steel cords of the carcass ply come in contact with the layer 1b during the tire life. The outer layer 1b is, in particular of an adhesive mixture, preferably from one of the usual Stahlkordgummierungsmischungen prepared, which is one of Karkassgummierungsmischung is very similar mixture. Table 1 contains a mixture example M1 for the outer layer 1b, the major constituents of the mixture and their proportions in phr (parts per 100 parts rubber) are given.<tables id="tabl0001" num="0001"><table frame="all"><title><b>Table 1</b></title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="43mm" /><colspec colnum="2" colname="col2" colwidth="24mm" /><thead><row><entry namest="col1" nameend="col2" align="center" valign="top"><b>M1 (outer layer 1b)</b></entry></row><row><entry align="center" valign="top"><b>Mixing ingredients</b></entry><entry align="center" valign="top"><b>Shares (phr)</b></entry></row></thead><tbody><row><entry>NO</entry><entry align="right">100.0</entry></row><row><entry>N326 (carbon black)</entry><entry align="right">55.0</entry></row><row><entry>Silica (SiO₂)</entry><entry align="right">8.0</entry></row><row><entry>resorcinol</entry><entry align="right">1.5</entry></row><row><entry>cobalt salt</entry><entry align="right">1.5</entry></row><row><entry>HMMM</entry><entry align="right">1.5</entry></row><row><entry>oil</entry><entry align="right">4.0</entry></row><row><entry>Antiaging agent</entry><entry align="right">2.0</entry></row><row><entry>ZnO</entry><entry align="right">8.0</entry></row><row><entry>Accelerators (z. B. DCBS)</entry><entry align="right">1.5</entry></row><row><entry>sulfur</entry><entry align="right">5.5</entry></row></tbody></tgroup></table></tables>

The proportion of natural rubber in this mixture can be between 60 phr and be 100 phr, it being possible in addition to natural rubber in the mixture also synthetic rubber, for example BR or SBR included. A certain proportion of silica of 3.0 phr up to 10 phr in the mixture is the shelf life of advantage. Resorcinol, HMMM, cobalt salt and ZnO (at a level of at least 4 phr) are responsible for a good steel cord and can be contained in the customary for such mixtures shares. To ensure good adhesion, are slowly crosslinking accelerators such as DCBS used, but are more expensive than faster vulcanizing accelerators such as CBS, or TBBS.

The communicating with the inner layer 2 is in contact inner layer 1a has a similar stiffness as the outer layer 1b. Under similar stiffness is to be understood that the hardness (Shore A) of the layers 1a and 1b by not more than 20% of each other. The rubber mixture for the layer 1 also has a viscosity that that of the blend for layer 1b corresponds to a minimum quantity already in tire building to prevent a Kordpenetration effective.

The inner layer 1a is made of a rubber compound, which is considerably cheaper to produce than the outer layer 1b, however, intended to prevent it from becoming the carcass on the inside of the tire, fully met. A mixture Example M2 for the inner layer 1a is provided in Table 2 again, the proportions of the constituents of the mixture are given here in phr.<tables id="tabl0002" num="0002"><table frame="all"><title><b>Table 2</b></title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="56mm" /><colspec colnum="2" colname="col2" colwidth="24mm" /><thead><row><entry namest="col1" nameend="col2" align="center" valign="top"><b>M2 (inner layer 1a)</b></entry></row><row><entry align="center" valign="top"><b>ingredients</b></entry><entry align="center" valign="top"><b>Shares (phr)</b></entry></row></thead><tbody><row><entry>NO</entry><entry align="right">50.0</entry></row><row><entry>SBR 1500</entry><entry align="right">50.0</entry></row><row><entry>N326 (carbon black)</entry><entry align="right">68.0</entry></row><row><entry>oil</entry><entry align="right">8.0</entry></row><row><entry>Antiaging agent</entry><entry align="right">2.0</entry></row><row><entry>ZnO</entry><entry align="right">3.0</entry></row><row><entry>Accelerators (z. B. CBS or TBBS)</entry><entry align="right">3.0</entry></row><row><entry>sulfur</entry><entry align="right">1.5</entry></row></tbody></tgroup></table></tables>

The rubber mixture M2 for the inner layer 1a has up to 60 parts by weight of natural rubber as another rubber component and styrene-butadiene rubber, such as SBR 1500 on. In the rubber component of the rubber mixture M2 further, other synthetic rubbers such as BR, may be present, wherein the proportion of synthetic rubber can be up to 100 phr. The rubber blend M2 preferably contains no a steel cord causing additives such as resorcinol, HMMM, and cobalt salt. As the filler, this mixture contains only carbon black. The proportion of ZnO is opposite to the rubber mixture for the outer layer 1b significantly reduced, since ZnO is not required here for the construction of an adhesive layer. Further, in this mixture of expensive accelerators such as DCBS, be dispensed with, since the mixture must not cure so slowly as is necessary for an adhesive mixture.

List of reference numerals

<dl id="dl0001" compact="compact"><dt>1</dt><dd>Squeegeelage</dd><dt>1a</dt><dd>inner layer</dd><dt>1b</dt><dd>outer layer</dd><dt>2</dt><dd>inner layer</dd><dt>3</dt><dd>carcass</dd><dt>5</dt><dd>carcass,</dd><dt>6</dt><dd>Karkassgummierung</dd></dl>