GB2411158A - Tyre sealant - Google Patents

Abstract

A tyre sealant formulation which demonstrates ideal properties for use in high speed vehicles is achieved by balancing the viscosity properties with ideal density. The required properties for slow moving vehicles involve a different balance of viscosity and density. Application of the invention described allows optimisation of formulations to give improved performance under the extremely differing conditions met by these vehicle types. The formulations also provide for the protection of the tyre and wheel components from corrosion and the freeze and excessive heat resistance required.

Description

IMPROVED TYRE SEALANT

This invention relates to a tyre sealant.

Basic tyre sealants have been in use since the 1960's and more recently developed to higher standards permitting use in a wider range of vehicle types. These cover from harsh off road use by heavy plant and equipment to demanding motorway use in cars and trucks. Prophylactic sealants are compounded from various ingredients and are installed in tyres, preferably from new, by pumping through the tyre valve stem. If at any time during the working life of the tyre a puncture occurs the sealant acts by flowing into the wound to prevent loss of pressure, this process continues after removal of the puncturing object, when a permanent plug normally is formed.

Most modem sealants form airtight seals but vary in their capability, often exhibiting serious faults and limitations.

In use, wheels can become persistently out of balance.

Others are difficult to inject due to clogging of the valve stem.

Some others are critically sensitive that precise quantities are injected otherwise the sealing properties are seriously compromised.

When vehicles are parked, some sealants can pool into the lower region of the tyre.

The above failings result from inadequate control of flow and fluid properties in the products in question.

Difficulty is encountered in other examples when removing deposits from inside tyres (the residues of) organic solvent based compounds used in some varieties of sealant in the event of a major conventional repair being necessary.

Incorrect and poorly formulated sealants cause corrosion within the tyre interior and or the wheel rim material.

Others required the tyre be removed from the rim for installation.

The foregoing, arise from formulation weaknesses in the respective systems and limit the fields of use or ease of application. For instance if wheel imbalance occurs the sealant cannot be used for high-speed road use in cars, but could serve well the needs of plant and equipment off road such as diggers and or golf buggies. If the sealant is not readily removable by simple,' washing and wiping then subsequent work to provide a structural repair to thus: tyre is compromised and possibly renders the tyre unusable. cat; A more broadly successful product will have low toxicity, be simple and problem free to install and remove (if required), whilst not compromising ariy - of the normal operating properties of the vehicle or tyre. Further, the inherent properties of the sealant (reduced running temperatures and consistent pressures) enhance tyre life, improve fuel economy, and contribute to safety. There is added benefit of boosted confidence for lone (female) drivers at not being made vulnerable by stranding at late hours. Fleet owners can benefit from huge savings on operating expense, savings on down time, late deliveries, and recovery charges. These factors contribute to a reduced strain on the environment.

The present invention described here, comprises a tyre sealant having constituent sub-components, each of which can be variably inter blended and compounded together in selected ratios such that the resultant properties of density and viscosity of the designated sealant can be manipulated to provide the optimum properties for a desired tyre sealant. The sub-components are in the main safe to handle in any concentration, except for active ingredients such as the biocides, which require handling and storage according to prescribed health and safety guidelines. At the fractional concentration levels these ingredients are used they represent little cause for concern.

The constituent sub-components include the following: a) A continuous suspending phase, which is the dispersion medium and cooling agent.

b) A polymeric binder.

c) Clumping and blocking agents.

d) Freezing and boiling point modifiers.

e) Inert filler compounded to make a high-density component.

fl Inert filler compounded to make a low-density component.

g) A corrosion inhibitor component.

h) A stabiliser, biocide and wetting agent (surfactant) component.

i) One or more thickening agents.

By necessity, each sub-component can consist of one or more individual ingredients. Those skilled in the art will know that individual ingredients could be required to be incorporated in one or more of the sub-components. Further those skilled in the art will know that individual ingredients can work together synergistically to produce a reinforced effect.

Examples of the sub-components relating to the list above are described here: a) Water and monoethylene glycol or a combination of the two or more similar materials.

b) Polyvinyl alcohol, polyvinyl acetate or acrylic emulsion.

c) Rayon fibre, similar synthetic or natural fibres, and natural or butyl rubber particulates and or hydrated clays.

d) Propylene glycol, ethylene glycol or other glycol and water miscible cellulose derivatives for instance methyl carboxy cellulose and hydroxy ethyl cellulose or mixtures of one or more.

e) Micronised barytes or other barium sulphate.

f) Micronised whiting, micronised hydrous magnesium silicate or fumed silica or blends of two or more.

g) Sodium nitrite or metasilicate and sodium benzoate or a blend of more than one.

h) Guaran or xanthan gum singly or as a blend of the two, and also with one or more similar galactomannans as stabilizer*. Myocide SP or Bronopol act as biocide and fungicide preferably used together or with one or more of the recognised as safe biocides** and fungicides**.

Suitable wetting agents*** are soya lecithin preferably in one of the water dispersible varieties.

i) Suitable examples of thickening agents include montmorillonite clays, methyl hydroxy propyi cellulose, and sodium carboxy nethylcellulose.

Some of these materials are internally electrolytically charged and others are neutral.

Those knowledgeable in the art will prepare suitable intermediate stages to enable the ingredients to be compounded together in the prescribed or otherwise required proportions to produce the sub-components.

In two embodiments of the invention, tyre sealants are produced according to the formulations 1 and 2 now described: 1 2 % % low high low high Binder (b) 2 25 2 25 Clumping agent (c) 1 22 1 22 Freezing/boiling Modifier. (d) 5 50 5 50 Inhibitor (g) 0.05 1.1 0.05 1.1 Thickening agent (i) 0.5 15 0.5 15 Stabiliser* (h*) 0.1 6.0 0.1 6.0 Biocide** (h**) 0.01 0.5 0.01 0.5 WeKing agent*** (h***) 0.01 2.2 0.01 2.2 Inert filler (e) 4.0 25 Inert filler (f) 4.0 25 Cooling/dispersion agent (a) to 100 to 100 In a preferred embodiment, a third tyre sealant 3 is produced constituting a blend of formulations 1 and 2 in the range between 100% of 1 and 100% of 2. In these embodiments the lowest specific gravity typically approximates to <1.1 as in formulation 1. The highest specific gravity is found in formulation 2 and is 1.60. The specific gravity of blended formulation 3 will lie between 1.1 and 1.6.

The fluid properties of formulation 3 and the viscosity in particular will be pseudoplastic and thixotropic.

In two other embodiments of the invention formulations _ and 5 are now described: 4 _ % % Binder (PVA emulsion) (b) 3 Binder (Polyvinyl alcohol) (b) 2.5 Clumping agent (rubber crumb 12 #) (c) 7 11 Clumping agent (rayon flock 0.5mm) (c) 3 6.7 Freezing/boiling modifier (monoethylene glycol)(d) 34 24 Inhibitor (sodium nitrite) (g) 0.5 Inhibitor (sodium metasilicate) (g) 0.6 Thickening agent (micronised magnesium silicate) (i) 3 Thickenig agent (sodium montmorillonite) (i) 7.0 Stabiliser*(Guaran) (h*) 0.1 Stabiliser* (Xanthan gum) (h*) 0.9 (Myocide SP) (h**) 0.02 0.1 Wetting agent*** (lecithin) (h***) 0.1 0.2 Inert filler (micronized whiting)(e) 15.28 22 Cooling/dispersion agent(water)(a) 34 25 Formulation 4 has weak pseudoplastic properties.

Formulation 5 has strong pseudoplastic properties.

Another embodiment formulation 6 has is a blend of formulation 4 and 5. %

Formulation 4 60 Formulation 5 40 The pseudoplastic properties of formulation 6 are intermediate between those of 4 and 5 and enumerated by measuring the viscosity in pascals or poise using a dynamic viscometer or rheometer of the Fann or Brookfield type. The density can be measured using a suitable calibrated cup, and enumerated in g/ml.

In use, for a given tyre' the sealant volume is calculated to cover the internal tread width, providing it with a coating of between 1mm and 4 mm thick depending on severity of service expected for the application. Note the side walls do not enter this calculation. For certain applications volumes will exceed this ideal, in order to provide a reserve for extended performance in the severe and demanding circumstances of repeating multiple punctures (found typically on waste and construction sites with heavy earth moving plant).

In order to achieve optimum effectiveness of the invention, the density and pseudoplasticity of the formulation may be adjusted as described herein above.

Claims (7)

1. A tyre sealant formulation system comprmag one or more means for controlling the sealant' pperbes of fluid flow md density

2. A tyre sealant formulation system as in 1. irpng a constituent or constituents capable of condoling Me pseudopla ucotropic and viscous flow properties of Me sealant

3. A type sealant formulation system as in 1 and 2. having a Constituent or constituents capable of varying the derby of the sealant.

4. A tyre sealant forrnulabon as in 2. and 3. using a At or constituents to depress its freezing point or apparel freezing Loire

5. A tyre sealant formulation system as in 2 3. and 4 having sealing and blocking properties in puncture apertures made in lyres.

6. A Ore sealant formulation substantially as described win property suitable for types on slow moving vehicles.

7. A tyre sealant formulation substantially as described win poppers suitable for bores on high speed vehicles