GB2474908A

GB2474908A - A floor tile comprising rubber crumb and polyolefin

Info

Publication number: GB2474908A
Application number: GB0919197A
Authority: GB
Inventors: Patrick Dormon; Keith Hall
Original assignee: CRUMB RUBBER Ltd
Current assignee: CRUMB RUBBER Ltd
Priority date: 2009-11-02
Filing date: 2009-11-02
Publication date: 2011-05-04
Also published as: GB0919197D0

Abstract

A floor tile comprises a polyolefin (30-90% by weight) and rubber crumb (10-70% by weight) wherein the particle size of the rubber crumb is less than 0.85mm. The polyolefin may be polypropylene or polyethylene. The floor tile may comprise polypropylene homopolymer (41%), rubber crumb (41%; particle size up to 0.24mm), flame retarder (15%), white pigment (titanium dioxide) and black pigment (carbon black). The floor tile composition may be free from fibres and metals. Alternatively, a floor the consists essentially of polyolefin, crumb rubber (having a particle size 0-0.85mm), flame retardant and pigment. Alternatively, compositions are defined wherein the particle diameter of the rubber crumb is less than about 7.0mm. The floor tiles may be produced via injection moulding, compression moulding, extrusion or stamping.

Description

FLOOR TILE

The present invention relates to a floor tile and to a method of its preparation.

Materials for use as floor coverings are known in the art. Thus, WO 2008/145131 discloses an air-laid, non-woven fibre material and a method of its manufacture. The material is intended for use in a mat, in particular for use as an insulation layer or batt. The material disclosed in WO 2008/1 45131 comprises: up to 98% recycled shredded material comprising a mixture of shredded fabric textile material fibres and residues of rubber and other components, all from recycled vehicle tyres; and from 1 to 30% of bi-component fibres having a length between 2 to 50mm. WO 2008/145131 appears to rely on the recycled tyres being shredded and clearly employs both the rubber from the tyres and the fibres obtained therefrom. It is also indicated that component (i) may also be supplemented with other recycled fibres, such as glass or carbon fibres. The fibres of component (i) are preferably from Ito 100 mm in length.

US 5,010,122 discloses formulating rubber particles having a size of less than 10 mesh (about 1.7 mm), a thermoplastic material and a coupling agent. The rubber particles and thermoplastic material are specified to be *:.::* present in a ratio of from 1:9 to 9:1, The rubber particles are preferably obtained from recycled rubber articles, with recycled tyres being specifically * *3** * mentioned. Thermoplastic materials include elastomers and olefinic ****.* * polymers. The coupling agent may comprise one or more reactive polymers, required to form a molecular bridge between the rubber particles and the thermoplastic. It is specifically disclosed in US 5,010,122 that the composite materials may be used to form such items as footwear, material handling products, floor mats, skid mats, agricultural products, dunnage devices, wheels, sound deadening products and tubing.

US 5,731, 358 is concerned with a process for the manufacture of high grade devulcanized rubber materials from scrap rubber items. The process involves combining the waste rubber material with from 0.5 to 5% wt polyethylene, polypropylene or a mixture thereof; mixing and heating the combination; cooling the resultant composition; adding to the resultant composition from 0.1 to 80% wt unvulcanized virgin rubber; heating the resulting mixture; and cooling. A wide range of sources of the waste rubber are disclosed, including natural rubbers, chioroprene, nitrile, styrene-butadiene rubber, polybutadiene, EPDM and the like. The material produced in the process of US 5,731,358 may be used in tyre retreads, footwear, insoles for shoes, solid tyres, carpet underlay, slippers, car mats and flaps.

US 6,228,295 discloses a composition comprising significant amounts of rubber obtained from recycled tyres. The composition comprises: recycled particulate rubber, preferably from 40 to 98%; a thermoplastic, preferably from to 30%; and expandable microspheres, preferably from 2 to 30%. The particulate rubber is specified to have a particle size of less than 10 mm and may be a powder. The rubber may contain remnants of fabric or steel cord.

The thermoplastic may be, for example, PE, PP, EVA or EPM. PP is indicated as being preferred. The expandable microspheres are said to be S...

: commercially available, for example ex. Akzo Nobel. The composition may be S...

"*." 25 used to form such products as building elements, including flooring underlay, insulated flooring, containers, pallets, pontoons and shock absorbers.

S

*.*.SS * US 2007/0042828 discloses a modular floor covering, in particular a covering formed from a plurality of interlocking mats. The covering is composed of: a base mat, preferably comprising a cellular foam or cross-linked rubber particles; a top mat, preferably comprising rubber from recycled tyres; and a top coat to provide a protective or decorative finish. The top mat may be formed from crumb rubber produced by grinding tyres and consolidated into a solid surfacing.

US 2007/0231532 discloses a rubber composition, the composition comprising a crumb rubber and a curable base rubber, together with a curing system. A further liquid rubber is preferably included in the mixture. The crumb rubber is preferably from recycled tyres. A wide range of curable base rubbers and liquid rubbers may be used, for example NR, SBR, NBR and EPDM rubber materials. The curing system is selected to be compatible with the base rubber. The rubber composition may be used to form floor coverings, such as mats or matting. A layer of the rubber composition may also be combined with a layer of woven or non-woven textile.

A rubber and textile mat is disclosed in US 2005/0031829. The mat comprises a first rubber layer and a second textile layer thermally bonded to the rubber layer. The rubber layer comprises rubber particles dispersed in a matrix of binder material and a barrier material. The rubber particles may be from recycled tyres and have a range of particle sizes. Particles of size from 5 mesh (about 4 mm) to 20 mesh (about 0.85 mm) are specifically mentioned.

The binder material in the matrix may be an adhesive or other binder, such as an isocyanate. The barrier material may be titanium oxide or the like. The textile layer is bonded to the rubber layer by means of heat and pressure. * �S S. * S...

US 5,883,182 is concerned with a coating composition. The coating composition is aqueous and contains from 2 to 60% of desuiphurized rubber * S.. S. * crumb having a mesh size of from 2 to 100 and from 20 to 60% of a binder. S....

* The rubber crumb may be derived from used tyres. The rubber crumb is said to improve flexibility of the coating and its adhesion to rubber, asphalt and PU foams, while allowing the water to escape during setting. The binder may be selected from a wide range of materials, including thermoplastic and thermosetting binders. The coating is particularly useful as a mastic for roofs and floors, as a sound deadening material, a moisture barrier or the like.

US 6,207,723 discloses a rubber composition comprising: a reclaimed rubber obtained by applying heat and shear stress to a vulcanized rubber; a non-vulcanized virgin rubber; and/or a thermoplastic resin. The reclaimed rubber is required to contain 40% or more of a residual toluene-insoluble gel component and a specific network chain density. The reclaimed rubber may be from recycled tyres. The virgin rubber may one or more of a natural rubber or a synthetic rubber. A wide range of thermoplastics may be used. The rubber composition may be used in forming a wide range of articles by moulding, for example interior and exterior rubber parts, hoses, packings, belts, weather strips, as well as a range of automobile interior and exterior components. The composition may also be used in tyre retreads.

A particularly advantageous covering for a floor is by way of floor tiles.

There is a need for an improved floor tile. It would be of advantage if the composition from which the floor tile is prepared could contain a significant amount of recycled materials, without impairing the properties of the tile or its use in covering a floor.

It has now been found that a particularly effective floor tile may be prepared from rubber crumb obtained from recycled vehicle tyres.

: Accordingly, in a first aspect, the present invention provides a floor tile S...

comprising a polyolefin present in an amount of from 30 to 90% by weight and rubber crumb present in an amount of from 10 to 70% by weight, the rubber S.....

* crumb having a particle size of less than 0.85 mm.

* S.... * *

:.:::. The composition of the floor tile comprises a polyolefin. Any suitable polyolefin or mixture of polyolefins may be used. Suitable polyolefins and blends thereof are known in the art and are commercially available. Preferred polyolefins are polyethylene and polypropylene, with polypropylene being a particularly preferred polyolefin. The polypropylene is most preferably a homopolymer. Alternatively, polypropylene copolymers may be employed.

The polyolefin may be virgin material. Alternatively, and more preferably, the floor tile contains recycled polyolefin, in particular recycled polypropylene.

Polypropylene for use in the floor tile of the present invention may vary in properties, according to the properties required in the finished tile. For example, the polypropylene may have a melt flow index in the range of from 5 to 20 g/l 0mm, more preferably from 10 to 15 g/l 0mm. A particularly suitable polypropylene has a melt flow index of about 12 g/lomin. The relative density of the polypropylene may be in the range of from 0.85 to 0.95, more preferably from 0.88 to 0.94, with a relative density of about 0.91 being particularly suitable for many applications. Similarly, the polypropylene may have a tensile stress of from 25 to 50 MPa, more preferably from 35 to 45 MPa, especially about 40 MPa. The Izod impact test value may be from 2 to 4 KJ/m2, more preferably from 2 to 3 KJ/m2, with an Izod value of about 2.5 KJ/m2 being suitable for many end uses.

The polyolefin is present in the composition of the floor tile in an amount of from 30 to 90% by weight. The polyolefin is preferably present in an amount of less than 90% by weight, more preferably less than 80%, still more preferably less than 70% by weight. The polyolefin is preferably present : in an amount of greater than 30% by weight, more preferably greater than 25 35% by weight, still more preferably greater than 40% by weight. A preferred range for the polyolefin content is from 30 to 80%, more preferably from 35 to 70%, still more preferably from 40 to 60% by weight. In one embodiment, the floor tile contains from 40 to 50% by weight polyolefin. S. -. S

The floor tile further comprises rubber crumb. The rubber crumb is obtained from recycled vehicle tyres. Suitable rubber crumb obtained in this manner is known in the art and available commercially. Processes for obtaining rubber crumb from recycled vehicle tyres are also known in the art.

One particularly preferred rubber crumb is obtained by a processing involving ambient grinding of recycled rubber tyres. Other suitable processing methods for preparing the rubber crumb include wet grinding and cryogenic grinding.

The rubber crumb included in the composition of the floor tile is most preferably essentially free from fibrous material and metal. Vehicle tyres contain significant quantities of fibres and metal wire. Accordingly, the rubber crumb present in the floor tile is most preferably prepared using a process that removes substantially all metal and fibrous material from the rubber crumb. In this way, the floor tile may be free from fibrous materials and metal, such as metal wire. It is particularly preferred that the floor tile is substantially free from metal components, such as metal wire present in vehicle tyres. Fibrous material from the recycled tyres may be present in the floor tile composition, preferably in a finely divided form. If present, the fibrous material is present in amounts of no greater than 5% wt, more preferably less than 4% wt, still more preferably less than 3% by weight.

Typically, the rubber crumb will have particles having a range of sizes.

The rubber crumb in the composition of the floor tile has a particle diameter of less than 0.85 mm, that is the rubber crumb particles are of a size to pass through a sieve with a U.S. mesh size of 20. Preferably, the rubber crumb : has a particle diameter of less than about 0.7 mm (U.S. mesh size of 25), " 25 more preferably a particle diameter of less than about 0.6 mm (U.S. mesh size of 30), still more preferably a particle diameter of less than about 0.5 mm (U.S. mesh size of 35). Embodiments of the floor tile of the present invention a.....

* have rubber crumb particles in a still smaller range, that is less than 0.45 mm in diameter (U.S. mesh size of 40), preferably less than 0.35mm (U.S. mesh size of 45), more preferably less than 0.3 mm (U.S. mesh size of 50), still more preferably less than 0.25 mm (U.S. mesh size of 60).

The rubber crumb is present in the composition of the floor tile in an amount of from 10 to 70% by weight. The rubber crumb is preferably present in an amount of greater than 20% by weight, more preferably greater than 30%, still more preferably greater than 40% by weight. The ratio of polyolefin to rubber crumb present in the composition of the floor tile may be varied, in order to obtain the required properties of the tile, such as density, hardness and the like. It is a particular advantage of the floor tile of the present invention that significant quantities of rubber crumb can be included, while still providing advantageous properties to the floor tile. Embodiments of the floor tile have the rubber crumb present in an amount of less than 65% by weight, more preferably less than 60% by weight, still more preferably less than 50% by weight. A preferred range for the rubber crumb content is from 30 to 60%, more preferably from 35 to 55%, still more preferably from 40 to 50% by weight. In one embodiment, the floor tile contains from 40 to 45% by weight or rubber crumb.

The floor tile may consist of polyolefin and rubber crumb. Alternatively, the composition of the floor tile may comprise one or more fillers and/or modifiers. Suitable fillers and modifiers for inclusion in the composition of the floor tile are known in the art and are commercially available.

* Suitable fillers include generally fine powder minerals. Other filler : materials include wood and recovered ash. The fillers are included in the ** 25 compositions to provide bulk to the composition at reduced cost and are present in amounts sufficient to reduce the overall cost of the product, without significant impairment to the properties of the composition and the finished tile. If present, the one or more fillers may be present in an amount of up to % by weight, for example in an amount of from 10 to 40% by weight, more preferably from 15 to 30% by weight. Examples of suitable fillers are metal carbonates, in particular calcium carbonate.

Modifiers are included in the composition of the floor tile to enhance the physical properties of the composition and the finished tile for specific end uses. A wide range of modifiers may be used, including oils, waxes and other polymers. The modifiers may be present in an amount sufficient to impart the desired end properties. Typically, if present, the one or more modifiers are present in an amount of up to 20% by weight, more preferably up to 15% by weight. Examples of suitable modifiers are polymers, in particular ethylene vinyl acetate (EVA).

In addition to the aforementioned components, the composition of the floor tile may also comprise further components, as will be apparent to the person skilled in the art. For example, the floor tile may comprise one or more fire and flame retardants. Suitable fire and flame retardants for polyolefin compositions are known in the art and commercially available. Examples of suitable fire flame retardants include halogenated compounds, such as decbromdiphenyl ether, and metal salts, such as antimony trioxide and aluminium trihyd rate.

The flame retardants may be included in the composition by way of pre-formulated masterbatches. Flame retardant masterbatches for use with polyolefin compositions are available commercially. *..I

s The fire and flame retardant may be present in any suitable amount to *...

*** 25 provide the required resistance to fire. The fire and flame retardant may be present in an amount of up to 25% by weight, more preferably up to 20% by * weight.

* * *.** * S :.:::. Further, the composition of the floor tile may comprise one or more pigments. Again, suitable pigment components and compositions for inclusion in polyolefiri compositions are known in the art and are commercially available. For example, suitable pigments for inclusion in the composition of the floor tile of the present invention include metal oxides, such as titanium oxide (hO2) and carbon black.

It is a particular advantage of the floor tile of the present invention that it may be formed using a minimum of components. Thus, the floor tile comprises polyolefin and rubber crumb in the amounts hereinbefore described, optionally with one or more fillers and/or modifiers, flame retarders and pigments. The floor tile of the present invention does not require the use of components required in the preparation of floor covering compositions of the prior art, such as coupling agents. Further, as mentioned above, it is particularly preferred that the rubber crumb is free from fibres and metal.

The pigments are included in the composition in the amount required to provide the desired colouration and pigmentation of the completed tile. The total pigment content of the composition may be up to 10% by weight, more preferably up to 5% by weight.

The floor tile of the present invention may be prepared in any suitable shape or configuration. In general, the floor tile will be generally flat or planar.

The thickness of the floor tile may be any suitable thickness required to provide a covering for the floor. For example, the floor tile may have a thickness of from 2 mm to 20 mm, preferably from 2 mm to 5 mm. S...

Thicknesses outside this range may be selected, as required by the duty to be * S.* 25 performed by the tile, when in use.

e..*..

The floor tile may be of any suitable or desired shape, for example polygonal, with square or rectangular floor tiles being particularly suitable for many uses. The tiles may be formed to have portions that interlock with adjacent tiles. Such interlocking forms for floor tiles are known in the art.

The major surfaces of the floor tile may be plain or bear a pattern or design. For example, one or both major surfaces of the floor tile may be provided with contours, so as to represent the surfaces of naturally occurring materials, such as stone, or be formed with a relief pattern to provide increased friction or grip to the surface of the tile.

The floor tile may be formed as single layer of the composition described above. Alternatively, the floor tile may comprise two or more layers, with the composition and physical properties of each layer being different. In this way, the floor tile may have one layer tailored to be presented to the floor surface to be covered and a second layer with different properties to be presented as the upper surface of the flooring.

The floor tile of the present invention may be formed to have a wide range of physical properties, to suit the needs of the floor tile when in use.

For example, the tile may be formed to exhibit a load at peak of at least 370 N, more preferably at least 390 N, still more preferably in excess of 400 N. The tile may exhibit a stress at peak of at least 9 N, more preferably at least N, still more preferably at least 12 N. The bend modulus of the finished tile is preferably at least 250 N/rn2, more preferably at least 275 N/rn2, still more preferably in excess of 300 N/rn2.

In a further aspect, the present invention provides a method of . : preparing a floor tile, the method comprising: * *** 25 combining a polyolefin and rubber crumb having a particle diameter of less than 085 mm in amounts to form a composition comprising from 30 to 90% by weight polyolefin and from 10 to 70% by weight rubber crumb; and : forming a floor tile from the composition. ****

The polyolefin and rubber crumb may be combined by any suitable technique. For example, the polyolefin is heated to above its melting point.

The melting point of the polyolefin will depend upon its composition and grade. For polypropylene, the melting point is approximately 165CC, again depending upon its molecular weight. The molten polyolefin may be then be combined with the rubber crumb by mixing. Should other components be included in the composition, as aforementioned, these may be added to the molten polyolefin and rubber crumb mixture. The components may be added directly, or by way of masterbatches, as known in the art. The components of the composition may be combined before the floor tile is formed, for example by mixing and subsequent forming into pellets, from which the floor tile is prepared, for example by moulding. Alternatively, the components may be combined during the process of forming the tile, for example by extrusion.

Once the composition has been prepared, the floor tile may be formed using any suitable technique. Suitable techniques are known in the art.

Examples of suitable techniques include injection moulding, compression moulding, extrusion and stamping.

In a further aspect, the present invention provides a floor covering comprising a plurality of floor tiles as hereinbefore described. In one embodiment, adjacent floor tiles in the floor covering are interlocked together.

* : EXAMPLE S...

A floor tile was prepared having the following composition (all percentages being in % weight of the final composition): Polypropylene homopolymer 41.0% Rubber Crumb 41.0% (particle diameter up to 0.24 mm) Flame Retarder 15.0% White Pigment (Ti02) 2.0% Black Pigment (carbon black) 1.0% The polypropylene was heated to above its melting point (about 165CC) until molten. The rubber crumb was added, together with the flame retarder (as a masterbatch) and the pigments, with mixing. The resulting mixture was formed into pellets, which were cooled and collected. The resulting pellets were used to form a floor tile using an injection moulding process.

The resulting floor tile when cooled had dimensions of 50 cm x 50 cm x 1.5 cm. The floor tile exhibit excellent properties as a floor covering.

-* * * ** * **** * * **** *

* *S*.. * S

S

S..... * S * S* * S S S...

Claims

CLAIMS1. A floor tile comprising a polyolefin present in an amount of from 30 to 90% by weight and rubber crumb present in an amount of from 10 to 70% by weight, the rubber crumb having a particle size of less than 0.85 mm.
2. The floor tile according to claim 1, wherein the polyolefin is polypropylene.
3. The floor tile according to either of claims 1 or 2, wherein the polyolefin is present in an amount in the range of from 35 to 70% by weight.
4. The floor tile according to claim 3, wherein the polyolefin is present in an amount in the range of from 40 to 60% by weight.
5. The floor tile according to any preceding claim, wherein the rubber crumb has a particle diameter of less than about 7.0 mm.
6. The floor tile according to claim 5, wherein the particle diameter of the rubber crumb is less than about 0.6 mm. S...
7. The floor tile according to claim 6, wherein the particle diameter of the *
S rubber crumb is less than about 5.0 mm.

* S5.*S * S 8. The floor tile according to any preceding claim, wherein the rubber : crumb is present in an amount of at least 20% by weight.
9. The floor tile according to claim 8, wherein the rubber crumb is present in an amount of at least 30% by weight.
10. The floor tile according to claim 9, wherein the rubber crumb is present in an amount of at least 40% by weight.
11. The floor tile according to any preceding claim, wherein the composition is free from fibres and metal.
12. The floor tile according to any preceding claim, further comprising one or more fillers and/or modifiers.
13. The floor tile according to claim 12, further comprising a flame retardant.
14. The floor tile according to claim 13, wherein the flame retardant is present in an amount of up to 20% by weight.
15. The floor tile according to any preceding claim, further comprising one or more pigments.
16. The floor tile according to any preceding claim, wherein at least one edge portion of the tile is formed so as to interlock with an adjacent tile.
17. The floor tile according to any preceding claim, wherein one or both ::::. major surfaces are provided with a pattern, relief or contours. 25

*
18. The floor tile according to any preceding claim, consisting of a single layer of the composition.
19. A floor tile consisting essentially of polyolefin, rubber crumb having a particle size in the range of from 0 to 0.85 mm, a flame retardant and at least one pigment.
20. A method of preparing a floor tile, the method comprising: combining a polyolefin and rubber crumb having a particle diameter of less than 0.85 mm in amounts to form a composition comprising from 30 to 90% by weight polyolefin and from 10 to 70% by weight rubber crumb; and forming a floor tile from the composition.
21. The method according to claim 20, wherein the floor tile is formed by injection moulding, compression moulding, extrusion or stamping.
22. A floor covering comprising a plurality of floor tiles according to any of claims Ito 19.
23. A floor tile substantially as hereinbefore described.
24. A method of preparing a floor tile substantially as hereinbefore described.
25. A floor covering substantially as hereinbefore described. S.. S * I SIS S * *.S... 25 * S*.*. * *S 5.... 4 S S *S * I a.,