A TEXTILE MATERIAL

A textile material

The present invention relates to a textile material in the form of a band suitable for the road contact belt portion of the traction device for automobile wheels of the type marketed under the trademark Autosock® and disclosed e.g. in European Patent EP 1165329 B9, which is hereby incorporated by reference. The invention also relates to a method for making such a textile material and a traction device incorporating such a material in its belt portion.

US Patent 2,682,907 which issued in 1956, discloses an early suggestion for a traction increasing device of the type in question made from a double layer of canvas forming both the central band region and flexible side portions provided with annular coil springs to make the device cling quite closely to the automobile wheel. The entire central band region is covered by a coating of abrasive particles set in adhesive applied to the double layer canvas material. The device is formed to cling quite closely to the automobile wheel. Furthermore, the glue covering the entire band region will significantly reduce its flexibility, the result being that the device according to US 2,682,907 would be virtually impossible to install on the wheel without first raising it from the ground. This drawback makes the device unsuitable for emergency use when the auto- mobile encounters a road surface covered by ice or snow.

Paradoxically, the applicant has discovered that the friction enhancing properties of a device according to US 2,682,907 may cause hazardous driving situations when the device is applied to the driven wheels of a modern day front wheel drive automobile. Particularly when driving on an icy surface, the friction of the front wheels will be so much higher than the friction of the rear wheels that the automobile will seriously over- steer when making a turn, the rear wheels loosing their lateral grip and sending the automobile into a spin. The same result may occur during breaking.

The overall purpose of the present invention is to obtain a traction device of the type in question with suitable friction properties during winter conditions while maintaining the possibility of easy installation under inclement whether conditions and without having to raise the wheel off the ground.

To permit the manufacture of such a device, the present invention provides a textile material in the form of a band which is provided at least partially with a binding agent

having abrasive particles adhering thereto, wherein said particles cover only a part of the surface area of the band, said part being preferably less than 60 % of said area. The invention also provides a device comprising such a band as defined in claim 9, and a method for making such a band as defined in claim 10.

Embodiments of the invention are defined in the dependent claims.

The invention will be described more closely below with reference to the exemplifying embodiments schematically shown in the appended drawings, wherein:

Figure l is a front view of a part of an apparatus for making a textile material according to the invention;

Figure 2 is a cross-section at a somewhat larger scale along the line II-II in Figure 1;

Figure 3 is a detail of Figure 2 at a larger scale of a second embodiment and with the opposite direction of rotation;

Figure 4 is a view similar to Figure 3 of a further embodiment;

Figure 5 is a plan view showing a section of fabric material according to the invention made with an apparatus incorporating the part shown in Figure 1 ;

Figure 6 shows a cross-section along the line VI-VI in Figure 5;

Figure 7 shows an enlarged detail of the patch pattern where indicated by VII in Figure

5;

Figure 8 shows at a smaller scale three possible variations of the patch pattern shown in Figure 7;

Figures 9-15 show schematically various possibilities of patch patterns combined with metal buttons for the textile material according to the invention;

Figure 16 shows a front view of a friction increasing device according to the invention;

Figure 17 is a lateral view of the outer side of the device shown in Figure 16; and

Figure {^is a lateral view of the inner side of the device shown in Figure 16.

The product Autosock® marketed by the applicant is a device to be fitted to an automobile wheel in order to increase friction between the wheel and the road surface during winter conditions. The device comprises a belt made substantially from a textile mate- rial for encircling the treadof the wheel and be held in place by means of the flexible inner and outer side portions. At least the inner side portion is tightened by means of an elastic member. The belt of the regular Autosock® is made of a polymer textile material, preferably polyester or polyamide textile material. The material is often referred to as RCF, which is an acronym for Road Contact Fabric. Further details of the RCF can be found in EP 1165329 B9. The Autosock® has gained very wide acceptance for its ease of use and excellent traction and durability properties.

For special applications, however, the applicant has modified the RCF by providing a part of its surface area with a layer of abrasive particles. These particles may be applied to the RCF in various patterns, e.g. stripes or spots, and the stripes or spots may in term be subdivided into smaller patches separated by areas of regular RCF in order not to impair significantly the flexibility of the RCF important for the dynamic behaviour and ease of installation of the Autosock®.

For producing such a modified RCF material on an industrial scale, the applicant suggests to use a modification of the rotary screen coating process. A drum 1 for such a process is shown in Figure 1. The drum has a series of spaced, circumferential sections 2 having a large number of closely spaced small holes arranged in groups according to the desired pattern of the patches, strips or spots of abrasive particles deposited on a substrate consisting of a web of RCF material.

Figure 2 is a cross-section showing the internals of the drum 1, where a so-called squeegee 3 forces a mixture 4 of abrasive particles mixed with a binding agent through the holes of the sections 2 of the drum 1. The thickness of the drum is exaggerated in Figure 2, and reference is made to Figures 3 and 4 which shows more clearly the perforations of the drum and alternate forms of the squeegee. It will be understood that the RCF substrate 5 passes underneath the drum 1 in synchronization therewith.

A section of the RCF substrate with stripes 6 of diamond-shaped or rhombic patches of abrasive material is shown in Figure 5. As indicated by dotted lines, the web 5 may be cut into six separate bands 7 once the binding agent of the mixture 4 has cured.

In this embodiment, each stripe 6 is subdivided into patches 8, as shown more clearly in Figure 7. Between the patches 8 there are separating portions 9 in order for the stripes 6 to be relatively flexible. Figure 8 shows alternate patterns for the patches and includes circles, squares and hexagons, but it will be understood that other forms, such as rectan- gles, triangles and pentagons may be chosen.

Figure 6 shows a cross-section of the substrate RCF with stripes 6 of abrasive material. It will be understood the substrate 5 with the stripes 6 are made in long continuous lengths and that the abrasive material deposited thereon may undergo various forms of treatment for curing or additional coating before the finished product is cut into the bands 7 for the production of Autosocks®.

The abrasive particles used in the mixture 4 can be made of various materials like A12O3, SiO, CrO3, ZrO2, quartz, diamond and combinations thereof. The binding agent of the mixture 4 may e.g. be a resin or polyurethane, and the abrasive material deposited on the substrate 5 may receive a top coat of a suitable polymer system, e.g. a polyester. The size of the abrasive particles may vary between 30 μm and 800 μm, the preferred size being about 600 μm. The area of the RCF to be covered by the abrasive particles should be less than 60 %, preferably less than 50 % and for a general application should cover about 40 %.

For certain road surface conditions like ice covered by sleet, the RCF with abrasive par- tides may benefit from metal buttons 9 and 11 shown in the exemplifying embodiments in Figures 9-15. These metal buttons may be made like the base part of regular press buttons used for garments, i.e. with one part on either side of the textile material connected together through a hole in the textile material. This connection can be a crimped connection. The holes may be melted if the RCF material is meltable, thus reinforcing the hole by means of the melted material. The buttons 9 can be placed in areas of the RCF where there is no abrasive material, as shown in Figures 9-11. The buttons 9. may be arranged in groups as shown in Figure 11, which also shows the patches 8 arranged in separate spots 10 rather than stripes.

Figures 12 and 13 show some of the buttons 9 arranged in areas where there is no abra- sive material, while other buttons 11 are mixed with the areas of abrasive particles. In the embodiments of Figures 14 and 15, all the buttons 11 are within the areas of the abrasive particles. The buttons 9, 11 are preferably made of steel.

Figure 16 shows a front view of a friction increasing device according to the invention in the form it would take when mounted on a wheel. The device has a road contacting belt 12 for encircling the tread of the wheel, the belt being made of a band 7 as shown in Figure 5 having two stripes 6 of abrasive material. The device further has an outer side portion 13, as better shown in Figure 17 and two criss-crossing straps 14. The inner side portion 15 is better shown in Figure 18 and is provided with an elastic member 16.

It will be understood that the invention is not restricted to the exemplifying embodiments shown in the appended drawings and discussed above, but may be varied and modified within the scope of the appending claims. Thus, if the stripes of abrasive mate- rial do not have to be broken up in discrete patches, but may be continuous, for instance for special heavy duty service, they may be applied to the RCF through a profile knife coating process. In such applications, the surface area of the RCF band coated by the abrasive particles may be higher, e.g. up to 75 %.

If the modified rotary screen method is difficult to apply, e.g. because the desired parti- cles should clog the openings of the drum 1, an alternate method may be to use the drum to apply only the binding agent onto the RCF 5 and then sprinkle abrasive particles onto those areas wetted by the binding agent. Any surplus particles could be vacuumed away after curing of the binding agent, and a further top coat could be applied to firmly anchor the abrasive particles. For all the methods, suction may be applied under- neath the RCF in the contact area with the drum to ascertain that the binding agent penetrates sufficiently into the RCF to provide sufficient bonding to the RCF.