DE2402639A1 - PNEUMATIC TIRES FOR MOTOR VEHICLES - Google Patents

Description

Dr. £ Wiegand. Dipl.-lne-W. HiemonR Dr. M. Kohler. Bipl.-lng. C. Gerhardt

Patent attorneys

Telex: 212979 lcarp d 2402639

W.26081 / 73 12 / Bm

Industry Pirelli S.p.A. Milan (Italy)

Pneumatic tires for motor vehicles.

The invention relates to pneumatic tires, which are particularly suitable for driving on icy surfaces and in particular the invention relates to the design of the tread and the Process for their manufacture.

There are different types of pneumatic tires for icy and snow-covered roads, i.e. particularly "slippery" roads have been suggested. These designs range from creating special tread patterns with deep grooves, which determine large tunnels, blocks or similar structures, up to the attachment of removable devices, for example snow chains on the tire. The common purpose of these explanations is to to improve the tire's grip on the ground.

Other designs that are between those given above Versions lie, include the insertion or insertion of foreign bodies of various

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Kind into the tread, these foreign bodies protruding from the surface of the tread.

In particular, running surfaces are known in which small bodies are incorporated into the mixture forming the running surface which have a hardness which is greater than the hardness of the mixture and which differ from should loosen the tread if they come to the surface as a result of wear of the tread, so that then a plurality of small cavities is formed, through which the tensile force of the tire on the Road is being improved.

Various treads are also known which contain metal spikes of various shapes, which protrude from the surface of the tread and exert a gripping effect on icy ground can, so that as a result, the grip of the tire is improved.

These latter versions can meet special requirements on the part of the user, however, they are not free from guardianship.

In fact, a tread, are embedded in the small foreign bodies that are to be solved to produce a plurality of small cavities on the surface of the tread, do not provide good adhesion of the tire on a surface or road that is completely covered with a thick layer of ice .

On the other hand, for example, studded tires capable of the required liability to create on thick layers of ice, he has certain loading · restrictions, #enn with him moved on roads that only partially a layer of ice. If not

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If there is ice, the spikes come with the road surface in direct contact and the adhesion of the tire is compared to the adhesion of a conventional, the spiked tire is much less so that it is required to run at a slower speed to drive. 7 / After all, there is the sound of studded tires running on asphalt roads, for example comparatively loud and accordingly extremely uncomfortable and undesirable.

In any event, the main disadvantages of studded tires are that they are not covered by ice Road surface is damaged to a considerable extent, so that annually high repair costs of roads damaged by studded tires.

The invention aims to provide a pneumatic tire that has good grip on ice, as it is for Studded tire is typical, but does not have the disadvantages indicated above.

Another purpose of the present invention is to provide a method of making a to create such a tire.

Accordingly, one object of the invention is a pneumatic tire for motor vehicles having a radial carcass, has a belt and a tread. Such a tire is characterized according to the invention that the tread has a plurality of spatial structures (cleats or blocks), whose peripheral walls are determined by a plurality of grooves on the surface of the tread Oriented in different directions, the mixture from which the spatial structures are formed

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are containing short fibers or thread with a modulus of elasticity that is at least 50 times as high .vie is the modulus of elasticity of the mixture, and da / i the fibers or threads at least on said 7 / änd are predominantly oriented in an essentially radial seal.

The main advantage obtained by the present invention resides in the fact that the three-dimensional structures of the tread, which contain the short fibers or threads, considerably more rigid as analog spatial Q-images without such fibers or threads are. In other words, the spatial structures according to the invention have a greater resistance to bending caused by a load acting on the tire in the radial direction, in the axial direction or in the circumferential direction is caused.

In this way, the spatial structures are able to move into the areas that cover the road surface Penetrate ice layer, so that accordingly a high degree of grip of the tire is guaranteed.

Furthermore, it has surprisingly been found that the short fibers or threads containing Spatial structures (lugs, blocks or the like.) Adhesion of the tire on ice-free roads, for example Asphalt road, ensure that the grip is considerably better than that obtained from studded tires ice-free roads, so that when using a tread according to the invention it is no longer necessary is to reduce the speed of the vehicle because of the noise generated by this tread

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is not louder than the noise made by normal winter tires. This gives probably due to the fact that the predominantly in a substantially radial direction oriented short thread or fiber some sort "Reinforcement" for the three-dimensional rubber structures (studs, blocks or the like) of the tread, so that the structure of these three-dimensional structures as a whole opposes the bending stresses mentioned above is more resistant, which enables the tire to adhere well to ice. However is the main element that comes into contact with the ground, in any case the rubber compound the spatial structure, so that the adhesion on ice-free roads compared to that existing with studded tires Adhesion is remarkably improved.

According to a preferred embodiment of the Invention comprises at least a part of the spatial structure with at least one radial projection a height in the range of 2 to 5 sam, this being Protrusion also contains short threads or fibers that run in a substantially radial direction are oriented. Preferably, this radial projection has the shape of a truncated cone, in which the radially inner diameter in the range from 3 to and the radially outer diameter in the range from 1 to 4 mm.

According to another preferred embodiment of the invention, the short threads or fibers are on the radially outermost surface of the tread partially visible.

The threads are preferably formed from metal

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and they have a length im. Range between 2 and 10 mm. Their diameter is in the range from 0.15 to 0.3o mm and their percentage by weight of the total weight of the rubber table; lies in the range between 1o and 5o %.

Alternatively, these threads are made of a polyamide (preferably "nylon").

For making a tire according to the invention The invention includes a method which because of its simple execution and its low Cost is particularly beneficial.

Accordingly, a further object of the invention is a method for producing a pneumatic tire which has a plurality of spatial structures which contain short fibers or threads which have a modulus of elasticity which is at least 50 times higher than the modulus of elasticity of the mixture of spatial structures and which are oriented in a substantially radial direction, have such a method is characterized according to the invention in that the rubber and the other usual components, which are contained in such a mixture mixed with an amount of the short fibers. The mixture containing the fibers or threads is mechanically treated to convert it into an elongated molding of a thickness in the range of 2 to 6 mm, in which most of the metal fibers are evenly distributed and in a direction substantially parallel to the size and dimension of the molded part is oriented ", The molded part is attached to a tread band, which may already be attached to a separately constructed tire,

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in which case the strands or threads predominate in Are oriented in the circumferential direction of the heating, and the tire is vulcanized in a mold, with the mixture of the standard part in the radial direction flows around the spatial structures and the grooves provided in the mold on the tread portion to be filled, and whereby the thread or fibers in substantially be oriented in the radial direction.

Preferably short metal threads or fibers in an amount between 10 and 5o wt.% Of the total weight of the mixture added, and the metal threads or fibers have a length in the range from 2 to 1o ■ and a diameter in the range between 0.15 and 0.3o mm.

The invention is explained below with reference to the drawing, for example.

Fig. 1 is a diagrammatic cross-sectional view

view of a tire according to the invention.

FIG. 2 is a schematic sectional view, on an enlarged scale, taken in FIG Circumferential direction of the tire, a spatial Structure of the tread according to FIG. 1 shows a pneumatic tire according to the invention, the one carcass, whose cords in radial planes of the tire and wound around the bead cores 2, 3, a belt 4 and a tread having.

The tread 5 has a particular for icy Roads, areas or the like. Suitable pattern, which a plurality of spatial structures such as tunnels or

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Has blocks 6, the peripheral walls 7 of which from Fig. 2 can be better seen, are determined by a plurality of deep grooves 8, the depth of which in Range from 10 to 13 mm.

On the radially outermost surface of each block there are protrusions 9 »which are located with reference to FIG the surface of the block 6 extend radially outward. Each projection 9 is frustoconical Shape whose radially inner diameter a (Fig. 2) is 4 mm, whose radially outer diameter b 2.5 is now, and its height Ii is 3.5 mm.

The tread band 5 is formed from two different mixtures, each one layer

10 and 11 form, of which the latter is located radially outward of the position 1o. The outer walls of the Blocks 6 and the projections 9 are out of the situation

11 forming mixture formed.

The mixture of layer 11 differs from the mixture of layer 10 in that it contains metal threads or fibers 12 (FIG. 2) which have a length of 3 »5 nua and a diameter of 0.2o mm. The percentage by weight of these metal threads or metal fibers is 30 % of the total weight of the mass forming the layer 11. The cylindrical surface of the metal fibers 12 is coated with a very thin brass film in order to ensure good bonding of the fibers 12 to the mixture containing them.

The two mixtures of layers 10 and 11 also preferably differ from one another with regard to the elastomeric materials or the ingredients therein, because the two

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Layers Ιο, 11 have different properties have to. In particular, the layer 1o should preferably be formed from a flexible or pliable mixture be on the one hand to compensate for the radial rigidity of the layer 11, and because they on the other hand connected to the sidewalls of the tire, the known repeated bends have to resist. In contrast, the layer 11 should preferably be formed from a mixture be that has good pulling power or pulling action on ice or snow j about the pulling power of the tire on the Road to further improve. Furthermore, this mixture preferably contains constituents that are necessary for this are suitable for obtaining a good bond with the metal fibers 12 contained in it.

As shown in FIG. 2, the blocks 6 and 9 are contained in the projections Metal fibers 12 predominantly in a direction parallel to the profile of the peripheral walls 7 of the blocks and the projections 9 oriented, and they are accordingly substantially in the radial direction of the Tire oriented. This orientation is considerably stronger on the peripheral walls 7 than in the middle parts of blocks 6.

On the radially outer surface of the projections 9, the metal fibers 12 can also over a length in of the order of 0.2 to 0.0 mm from that of the protrusions 9 protrude forming rubber mixture.

At the foot 13 of the "blocks 6" are the metal fibers predominantly oriented in the circumferential direction of the tire, as already stated above, can be used to manufacture

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of a tire according to the invention is a particular one easy-to-use method used advantageously will.

The mixture which is to form the layer 11 is in a closed mill with known Working method established. This mixture can be composed, for example, as follows:

Elastomer (1) 1oo Parts Antioxidants 2.5 Il Binders for metal (2) 2 ti Zinc oxide 6th Il ISAF soot 48 Il SiO ₂ 5 II accelerator 1 It Stearic acid It Plasticizers 2 It sulfur 2.2 Il

(1) The plastic can be natural rubber or a composition of natural rubber with styrene butadiene or styrene-polybutadiene copolymers (as such or oil-extended)

in various proportions that are suitable to give a mixture, their Embrittlement point, measured in accordance with the standard ASTM D 746 - 57 T equal or is less than -6o C.

(2JThe binders for metal can be used in technology

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known cobalt compounds or combinations of reactive binder resins, which also are known.

After mixing, the metal fibers 12 which have a length of 3 »5 mm and a diameter of o, 2o mm, in an amount of $ o wt. Of the total weight of the iviischung ο input thereto. The mixture containing the fibers is then subjected to a further mixing process so that the fibers 12 are incorporated into the mixture.

The mixture obtained is allowed to pass between the rollers of an open mill and processed for a time sufficient to keep the metal fibers 12 uniform in the mixture to disperse.

A first molding is then made from the mixture by extrusion in an extruder or through Calendering received. This molded part has a thickness of about 3 mm, elongated shape and the desired Width, and in its body most of the metal fibers 12 are in the direction of movement of the molded part is oriented according to the phenomena known in the art of rubber production.

At the same time, a second molded part of the desired Size manufactured separately using known working methods. This molded part should position 1o form and the mixture forming it can essentially be a conventional tread compound, the for example, have the following composition can:

Elastomer (1) 100 parts

Antioxidant 2 "

A09830 / 041 8

ISAF carbon black 65 parts

Plasticizer 15 "

Zinc oxide 3.5 "

Accelerator 1 "

Stearic acid 2 "

Sulfur 2

(1) The elastomer can be natural rubber or a composition of natural rubber. rubber with styrene butadiene or mixed styrene polybutadiene polymers (as such or oil-mixed) in various proportions that are suitable are to result in a mixture whose embrittlement point measured according to ASTM D 7 ^ 6 -57 T standard, is equal to or lower than -55 C.

The first molded part containing the metal fibers is placed over the second molded part, and then the overall structure on deia is produced separately Tire assembly mounted such that the first mold part extends radially outward of the second mold part is located.

The tire thus obtained is then vulcanized in a mold. During the vulcanization process "the mixture of the molded part forming the layer 11 flows radially in the direction against the three-dimensional structures and blocks and grooves, respectively, which are present in the mold on the tread part, during this Movement of the metal fibers contained in this mixture, dragged along and at least to a large extent Part are oriented in the substantially radial direction of the tire.

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Claims (8)

Claims 1.1 Pneumatic tires for motor vehicles, with a radial carcass, a belt and a tread, the barrel flat having a riehrzahl of
Spatial structures such as blocks, lugs or the like, whose peripheral walls are determined by a plurality of grooves which are oriented in different directions on the surface of the tread, characterized in that the mixture forming the spatial structures (6) is short
Contains filaments or fibers (12) which have a modulus of elasticity which is at least 50 times as high as the modulus of elasticity of the mixture and which are oriented predominantly in a substantially radial direction at least on said walls (7). 2. Pneumatic tire according to claim 1, characterized in that at least some of the three-dimensional structures (6) have at least one radial projection (9) which has a height in the area
between 2 and 5 mm and in which short fibers (12) are contained, which are oriented in a substantially radial direction. 3. Pneumatic tire according to claim 2, characterized in that each radial projection (9)
Has frustoconical shape, the radial
inner diameter ranging from 3 to 7 now, A-O 9830/0418 and the radially outer diameter of which is in the range of 1 to 4 µm. 4-, pneumatic tire according to one of claims 1 "to 3, characterized in that the short fibers (12) are partially visible on the radially "outer surface of the barrel flat. 5. Pneumatic tire according to one of claims 1 to 4-, characterized in that the short fibers (12) are formed from metal and have a length in the range between 2 and .10 mm and a diameter in the range from 0.15 to 0.3o mm, and that their percentage by weight in the range between 1o and 5o% of the total weight of the mixture. 6. Pneumatic tire according to one of claims 1 to ^, characterized in that the short fibers are formed from polyamide. 7. A method for producing a pneumatic tire, in particular according to one of claims 1 to 6, characterized characterized in that rubber and other common ingredients are included in a mixture are, with a lot of short threads or fibers, whose modulus of elasticity is at least 50 times as high Modulus of elasticity of the mixture is to be mixed, the mixture containing the filaments or fibers is mechanically treated to make it into an elongated molding having a thickness in the range of 2 to 6 mm to convert in which most of the threads or fibers in one direction essentially is evenly distributed parallel to the larger dimension of the molded part, the molded part on one Tread band, which may already be attached to a separately built tire, attached are, the threads or fibers are predominantly oriented in the circumferential direction of the tire, and the tire is vulcanized in a mold, the mixture of the molded part in radial Direction flows and the tread pattern formed on the mold fills, and by the flow of the mixture the threads or fibers in substantially be oriented in the radial direction. 8. The method according to claim 7, characterized in that that short fibers or threads of the mixture in an amount between 1o and 5o% of the total weight are added to the mixture, and that fibers or threads with a length between 2 and 10 mm and a diameter between 0.15 and o.3o mm can be used. 9. Method according to claim 7 or 8, characterized in that short metal threads or metal fibers be used. 1o. Method according to claim 7 or 8, characterized in that short threads or fibers are made of Plastic, preferably polyamide, can be used. / ς Blank page