DE102009003333A1 - Sealant made of viscoelastic gel, useful e.g. to produce self-sealing vehicle pneumatic tire, comprises a filler made of polymers, preferably of rubber, optionally vulcanized rubber or polyurethane in the form of particles - Google Patents

Abstract

Sealant made of viscoelastic gel comprises filler made of polymers, preferably of rubber, optionally vulcanized rubber or polyurethane in the form of particles having an average diameter of 0.05-8 mm. Independent claims are included for: (1) a self-sealing vehicle pneumatic tire, which is composed of several layers of rubber-elastomer and strength supports, comprising at least one sealant layer from the sealant; and (2) producing self-sealing vehicle pneumatic tire comprising applying one or more gel-type, sealant layer containing the filler within the layer-wise construction of a green tire made of at least inner layer, carcass, sidewalls, strap layer and treads.

Description

The The invention relates to a viscoelastic gel sealant Self-sealing pneumatic vehicle tires made of viscoelastic gel, one Self-sealing pneumatic vehicle tire equipped with the sealant is the method of making this self-sealing pneumatic vehicle tire and the use of the sealant in pneumatic vehicle tires.

sealant for pneumatic tires are used, occurring leaks to seal after perforations of the tire. Known are sealants that used as a repair agent only after the occurrence of leakage Like other sealants that are used with pneumatic vehicle tires be treated before use, that they occur when they occur the perforation self-sealing behave.

requirement It is that the tire sealant is so low viscous that reliably prevents air leakage at the perforation It can be that when operating the tire at the desired Place remains, and that it is its sealing property long Retains time. In addition, the sealant must be good with connect to the adjacent tire layers.

From the US Pat. No. 6,837,287 B1 and from the EP 1 533 108 A2 are tubeless pneumatic tires with an intermediate layer of sealant precursor in the green tire (green tire) known, the sealant precursor during the tire vulcanization deliberately partially depolymerized. However, a targeted depolymerization reaction during vulcanization is limited to a few systems, moreover, it seems necessary to provide special rubbers adjacent to the sealant precursor layer. Specifically, these documents disclose the use of halobutyl rubbers. Moreover, the quasi-liquid parts produced by the depolymerization reaction could cause imbalance if their distribution in the tire changes, leading to tire uniformity (TU) problems.

The WO 2008/071361 discloses the use of a polyurethane gel in a pneumatic vehicle tire or as a sealant for the production of self-sealing vehicle tires. The polyurethane gel described herein, which is already known from the EP 57838 and the EP 511 570 For use in pressure-distributing elements (eg, upholstery), it was possible to seal a tire so that it was leak-proof for at least 1 week despite being perforated with nails without a driving load. Even after removal of the nails, the tire remained tight for at least another week. However, a tire equipped with this sealant was limited in its ability to withstand driving under test conditions.

A Improvement of the sealing ability of such a sealant is therefore essential to strive for.

task Accordingly, it is the object of the present invention to provide a pneumatic vehicle tire with a sealant layer which can be integrated and vulcanized in tire construction equip so that the sealing ability of the tire significantly improved after perforation of the tread becomes.

Solved The object is achieved by providing a sealant of viscoelastic Gel containing a filler of polymers, in particular of rubber, of unvulcanised or vulcanised rubber or polyurethane in the form of particles having a mean particle size from 0.05 to 8 mm.

When Polymers are here all substances that by polymerization, polycondensation, Polyaddition etc. arise, understood. Preference is given to synthetic Polymers or copolymers, in particular polyolefins and its copolymers suitable. Also particularly suitable are elastomers, in particular vulcanized or unvulcanized rubber. In particular Tire rubber including tire rubber from recycled Used tires as filler.

to Extraction of the particles can be cut and / or vulcanized rubber be ground. If desired, the rubber powder or granules of a chemical treatment for activating the surface be subjected.

rubber can be unvulcanized or vulcanized as such or even after Activation of its surface used as a filler become. Appropriate types of surface activation are known in rubber technology. All kinds of natural or synthetic rubber can be used. Preferably, the filler is recycled Rubber.

The filler has a higher hardness than the base gel itself. The Shore 000 hardness (after ASTM D 2240 ). Preferably, the Shore 000 hardness of the filler is at least 10 Shore 000 units higher than the Shore hardness of the gel. The Shore hardness difference between filler and gel is preferably at least 20 and more preferably at least 30 Shore 000 units.

Preferably the filler consists of particles with a medium Particle size of 0.05 to 5 mm, more preferably 0.05 to 3 mm and more preferably 0.1 to 1 mm.

The mean particle size is a statistical mean to understand the item sizes. As a single particle size the mean diameter of the may be irregular shaped single particle indicated. The dispersion or distribution width around the average particle size preferably between 0.1 and 7.95 mm (double standard deviation around the distribution mean).

Of the Diameter of the filler should be the layer thickness of the Never exceed the sealant layer.

Of the Proportion of filler particles is preferably at least 3 wt .-% based on the total weight of the gel mass. In particular, at least 5% by weight, and more preferably at least 10 wt .-% filler based on the total weight of the gel mass containing sealant.

at the most are up to 60% by weight, preferably up to 40% by weight, and especially preferably up to 30 wt .-% of filler based on the Total weight of the gel mass contained in the sealant.

Of the Filler significantly improves the sealing properties Dimensions by serving as a plug and thereby a perforation stronger seal.

When Base material for the sealant becomes a heat and thus vulcanization-stable gel used. Gels consist of a matrix and a matrix filling dispersant which is bound by main and secondary virtues.

This Construction requires the typical properties of a gel such as dimensional stability and limited flowability at the same time Elasticity. Thus, viscoelastic gels penetrating foreign bodies, eg. As nails, screws etc. evade and after removing the same smaller cavities, Seal cracks, cuts and the like quickly.

Preferably For the sealant is a gel from the group of polyurethane gels and the silicone gels or highly viscous crosslinked butyl rubber compounds selected.

Polyurethane gels are dimensionally stable and viscoelastic. As a special measure suitable polyurethane gels to call, by an excess are characterized in isocyanate-reactive component. Especially polyurethane gels whose isocyanate component is an MDI, HDI or TDI-containing isocyanate, especially in the form of a prepolymer with a polyether polyol.

Further preferably suitable is a polyurethane gel, which from the reaction is formed by at least one isocyanate and at least one polyol, wherein the isocyanate index of the polyurethane gel is between 15 and 80 and the Geldispersionsmittel from a part of the polyol consists. The isocyanate index describes the ratio of in the reaction used free NCO groups to the free OH groups. The equivalent ratio (NCO / OH) × 100 gives the corresponding Isocyanatkenzahl.

Silicone gels are cross-linking two-component silicone elastomers, with non-reactive silicone oil serving as the dispersant. They are used, among other things, as a material for pressure equalization (shock absorber) and for embedding electrical components. Silicone gels have been disclosed, inter alia, in the following writings: US 4,600,261 . US 4,634,207 . US 5,140,746 . US 5,357,057 . US 5,079,300 . US 4,777,063 . US 5,257,058 and in the US 3,020,240 ,

The Sealant can be prefabricated as such and as a strip or Stains, preferably at least in the width of the tread and in a length corresponding to the tire circumference at the for the sealant position provided position corresponds to be provided. Another preferred embodiment of such a sealant strip or sealant spot has a length corresponding to the tire circumference the inner layer of the tire corresponds.

Further The task is accomplished by providing a self-sealing Pneumatic vehicle tire with a self-perforating against Sealing objects that can be integrated in tire building and vulcanizable sealant layer of the invention Sealant achieved.

Sealant layer in the sense of the invention means that these completely or partially rubber and / or reinforcements surrounded by the tire. The filler-containing sealant layer can be used at all possible positions of a standard made of several layers of rubber and reinforcements Pneumatic vehicle tires are provided.

According to the invention but also several sealant layers in such a self-sealing Tires are present. For example, a sealant can on the inside of the tire facing the inner layer (inner liner). But also between inner layer and tread can realize one or more layers of sealant become.

When multiple layers of sealant are present, they are generally covered by other layers commonly found in tire manufacture separated from each other.

The Thickness of the sealant layer is preferably 1 to 20 mm, preferably 1 to 10 mm and more preferably 2 to 5 mm.

Preferably the filler is substantially uniform distributed in the sealant layer.

The The invention further comprises a method for producing a self-sealing pneumatic vehicle tire, in accordance with the invention a or more preformed gel and filler containing Sealant layers within the positional structure of a vehicle tire blank consisting of at least inner layer, carcass, sidewalls, Gurtlagen and treads are introduced.

The individual layers present on each tire are standard produced by strip-shaped or profiled extrusion. Layers, containing the reinforcements are calendered. Subsequently For example, the prefabricated layers on a winding machine a collapsible drum successively from the inside out applied, starting with the airtight inner layer and subsequently the carcass, the side walls, the belt layers all the way to the external treads. The thus obtained green tire is in a form that by default also for Forming the tire profile leads, at a vulcanization temperature depending on the rubber mixtures between 130 and 200 ° Celsius vulcanized for about 10 to 15 minutes under pressure.

there are there various possibilities for the invention (s) Apply sealant layer (s) in the tire.

The Gels of the sealant layers are preferred with the invention Prefabricated fillers and in the desired Size provided so that the filler-containing Sealant layer in normal tire construction can be processed before vulcanization.

Especially is the prefabricated filler-containing sealant layer strip-shaped introduced into the green tire, wherein the length of the strip corresponds to the circumference at the position, located at the filler-containing sealant layer becomes.

In In a preferred embodiment, the sealant layer positioned on the inner layer and the length of the strip corresponds to the extent of the position of the sealant layer on the inner layer.

Further can the desired thickness of the sealant layer by multiple wrapping with a thinner sealant layer be achieved.

The Width of the sealant layer preferably corresponds to the width of the Tread.

In alternative embodiment, the provided Sealant also made with a reactive coating become. For this purpose, a reaction mixture for the preparation of the viscoelastic gel applied to at least one tire layer. In particular, the reactive coating can be sprayed, Pouring, painting or other techniques are applied.

In In another embodiment, the reaction mixture applied on the inside (air side) of the finished green tire and then by spinning in a uniform layer thickness distributed.

Around an even stronger adhesion between filler-containing Sealant and the other tire components to In addition, a tire in the usual way Adhesive are applied to the contact surfaces.

The Invention will be explained below by way of example. This is for illustrative purposes only and is not intended to be in any way Way restrict the invention.

Examples

For the sealant layer is a 2-component polyurethane gel Fa. Technogel ^® was used. For this purpose, the reactive two-component polyurethane system with the filler is introduced into the finished tire while it is rotated at a speed of 20-500 l / min, so as to achieve a uniform distribution of the sealant inside the tire. As a filler, tire rubber made from recycled waste tires was used in particles having an average particle size of 0.1 to 1 mm.

1. The polyurethane gel had the following specifications:

• trifunctional polyol having an OH number of 36;
• HDI-based isocyanate with an NCO content of about 12% (Desmodur E 305);
• Polyol to isocyanate 10: 1;
• bismuth-organic catalyst (Coscat 83)
• preferably filled with 10 to 30 wt .-% of a vegetable oil.

2. Vulcanization on the specimen:

The polyurethane gel was mixed between two layers of standard tire mix (NR-Kaut schuk-based, soot-reinforced, sulfur-crosslinked) introduced and vulcanized in a standard hot press for 15 min at 160 ° C and high pressure.

3. Test on the tire:

in the The invention will be described in more detail below with reference to an illustration explained. The figure shows a pneumatic tire in cross section, which contains a tire sealant and in the area of the tread perforated by a nail.

in the Please refer to the attached drawings below: Reference numerals:

1

tires

3

tread

5

1 Location sealant

6

granules

A

nail

The mature 1 owns a tread 3 with a tread this 3 underlying layer of the tire sealant 5 , At a position A pierces a nail both the tread and the underlying sealant layer and penetrates into the tire inside.

As The tests described below will show that when pulling out the nail resulting leakage reliably sealed. At the Flow of the sealant in the resulting leak Existing filler particles can seal the sealing The effect is even greater, due to the particle size in addition, close the leak like a plug. This manifests itself as shown below in a significantly improved density retention capability.

test results

1. tire without sealant (comparative example)

• 1.1. A tire without sealant was on a rim mounted. Subsequently, this was 2.5 filled with air pressure. In total, 6 nails driven in the tires (2 nails with 3.5 mm, 2 nails with 4.2 mm and 2 nails with 5.5 mm diameter) and that so that every nail completely pierced the tire and sticking out in the interior. After 24 hours, the air was completely out of the Tires escaped.
• 1.2. The same tire was then used again 2.5 bar air pressure filled. All 6 nails were out pulled the tire. After 2 minutes, the air was completely out of the Tires escaped.

2. Tires with filler sealant

• 2.1. One with a sealant layer after Example 1 provided, pierced with corresponding nails The tire was airtight when the nails were still in the tire.
• 2.2. Even after removing the nails, the tire remained tight and lost no air. The tire could with normal speed be driven in this condition without losing air.
• 2.3 In addition, the tire has undergone a test procedure subjected: The tire was filled with 2.5 bas air pressure and pressed with 4200 N against a test drum and at first 90 km / h over 108 minutes warm hazards. Subsequently, the same 6 nails used as described under 1.1 to the tread too perforate. Each nail reached into the interior of the tire. After that the tire ran on with 4200 N load at 90 km / h. leaks occurred only after 39, 53, 62 and 112 hours running time. Only after 185 hours of running leaked the last remaining Nail up.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 6837287 B1 [0004]
• - EP 1533108 A2 [0004]
• - WO 2008/071361 [0005]
• - EP 57838 [0005]
• - EP 511570 [0005]
• US 4600261 [0024]
• US 4634207 [0024]
• US 5140746 [0024]
• US 5357057 [0024]
• - US 5079300 [0024]
• US 4777063 [0024]
• - US 5257058 [0024]
• US 3,020,240 [0024]

Cited non-patent literature

• ASTM D 2240 [0012]

Claims (13)

Sealant of viscoelastic gel for self-sealing pneumatic vehicle tires, characterized in that a filler of polymers, in particular of rubber, unvulcanized or vulcanized rubber or polyurethane in the form of particles having a mean diameter of 0.05 to 8 mm, is included. Sealant according to claim 1, characterized in that that the filler consists of particles with a mean diameter from 0.05 to 5 mm. Sealant according to claim 1 or 2, characterized that at least 3 wt .-% filler particles based on the total weight of the gel mass are contained. Sealant according to one of claims 1 to 3, characterized in that up to 60 wt .-%, preferably to at 40% by weight and more preferably up to 30% by weight of filler particles are contained based on the total weight of the gel mass. Sealant according to one of claims 1 to 4, characterized in that the gel is selected from the group of polyurethane gels and silicone gels or high viscosity Anvernetzte Butylkautschukmischungen. Self-sealing pneumatic vehicle tire consisting of several Layers of rubber elastomers and strength supports constructed is, characterized in that it has at least one sealant layer from the sealant according to claims 1 to 5. Self-sealing pneumatic vehicle tire according to claim 7, characterized in that the sealant layer (s) has a layer thickness from 1 to 20 mm, preferably 1 to 10 mm and more preferably 2 to 5 mm owns. Self-sealing pneumatic vehicle tire according to claim 6 or 7, characterized in that one or more sealant layer (s) disposed between the inner layer and the tread of the pneumatic tire is / are. Self-sealing pneumatic vehicle tire after one of claims 6 to 8, characterized in that a Sealant on the inside of the tire facing side of the Inner layer of the tire is arranged. Method for producing self-sealing pneumatic vehicle tires, characterized in that one or more gel, the filler-containing sealant layers within the layered structure of a green tire made of at least inner layer, Carcass, side walls, belt layers and treads introduced become. Method for producing self-sealing pneumatic vehicle tires according to claim 10, characterized in that the sealant layer (s) introduced into the green tire and then the tire in the usual Way is completed by vulcanization. Method for producing self-sealing pneumatic vehicle tires, characterized in that a reaction mixture for the preparation of the viscoelastic gel according to any one of claims 1 to 5 is applied to at least one tire layer, before the during or reacted after the tire construction to the sealant layer. Use of the sealant according to one of the claims 1 to 6 for the production of self-sealing pneumatic vehicle tires or for sealing damaged pneumatic vehicle tires.