DESCRIPTION

This invention concerns grout compositions. For many commercial and industrial locations particularly those handling foodstuffs, such as food processing factories, bakeries, dairies, creameries and abattoirs, the ideal cladding material for both floors and walls is ceramic tiles. It is important that the joints between the tiles are filled with a durable, impervious, non-absorbent chemically resistant grouting material, ie., one which is resistant to the corrosive liquids which are often produced as part of the manufacturing process or as part of the strong cleaning operations that are used to maintain hygienic conditions. The grout must also resist the action of high-pressure water jets or steam cleaners and must have a surface which is easy to clean and where necessary disinfect.

Chemically resistant ceramic tile grouts are normally based upon a reactive resin, such as an epoxide resin, a polyester resin or a furane resin. The grout is often mixed to a mortar-like consistency and is applied into the joints by means of gunning, hand- pointing or by use of a grouting squeegee.

Non-water dispersible, polymer-based grouts, such as those based upon polyester resin, can be applied to a tiled surface which has been pre-treated with a wax dispersion in solvent or a water-based emulsion sealer. The sealer prevents the grout from contacting the tile surface- Once the grout has cured and set, the protective wax and residual grout can be readily removed from the tile surface by being physically scraped off.

This can be facilitated by the application of steam to the protected surface.

Ξpoxide resin based grouts, however, are normally provided in their water dispersible form and are cleaned from the tile surface immediately after application and before the resin cures by means of water, abrasive pads, sponges, cloths and the like. Care has to be taken when cleaning off these joints to remove all the excess grout from the tile surface, the action of which often causes grout to be removed from the joint, particularly if the grout joint between the tiles is wide. This action is a time-consuming process.

The mortar like consistency of these grouts causes it to be difficult to completely fill the joints between tiles. Air voids are often trapped in the grout during application which provides a source of weakness in the cured grout joint> When the tiled finish is subjected to the corrosive elements of aggressive

liquids and steam cleaning, these voids are often the source of initial chemical attack which begins to break down the tile bedding system beneath the tiles.

One of the problems associated with polyester grouts is a result of styrene vapour that is emitted during the application of the grout. This makes it very important that well ventilated conditions exist during the application of the grout. The presence of styrene vapour also presents problems if a floor should be grouted in a food processing plant where the food being processed in adjacent areas can be heavily tainted by the styrene vapours.

An object of this invention is to provide a grout composition suitable for use in commercial ceramic floor tile installations, particularly those involving food processing which may not give rise to the above mentioned disadvantages.

According to the invention there is provided a grout composition having a first component comprising a curable epoxy resin, a second component comprising a hardener for the curable epoxy resin and a third component comprising a filler.

The present invention further provides a method of grouting tiles comprising the step of applying to joints between tiles of an array of tiles a composition produced by mixing a first component that comprises a

curable epoxy resin, a second component that comprises a hardener for the curable epoxy resin and a third component that comprises filler.

The third component comprising filler may be pre- blended with one or both of the first and second components.

The preferred grout compositions of the invention have a relatively low viscosity so that they are flowable. Typically suitable viscosities for a blended grout composition of the invention are in the range of 7000-14,000 illipascals (spindle 5, 5 rpm ERV -8 viscometer at 20 degrees centigrade), preferably about 10,000 millipascals (spindle 5, 5 rpm)

The method of the invention preferably further comprises the step of applying to the upper surface of the tiles _r which preferably have been fixed in a bed of a suitable ceramic tile adhesive or of a cement-sand mortar, a protective coating prior to application of the grouting composition. The protective layer is preferably of wax, especially paraffin wax but may also be a water-based emulsion sealer. The wax is preferably applied as a dispersion in a solvent. The solvent is preferably one that evaporates readily but which is relatively innocuous. Examples of suitable solvents for that purpose include white spirit or petroleum spirit. The solids content of wax in the dispersion is

preferably in the range of from 20 to 40% by weight.

The protective layer may be applied by means of a roller, preferably a soft roller, such as of lambswool or the like, or a closed cell plastics roller. Once the grout composition has been applied and has set, the protective layer and residual grout is preferably easily removed from the tiles. A protective wax layer may be readily removed by scraping after application of heat or steam. It is not essential to remove the protective layer soon after, grouting. The protective layer may be left until any other work in that area is completed in order to protect the floor.

In order to obtain a neat grout joint, for example between cushion edge tiles or to produce a slightly recessed joint, if required, the joints may be treated, whilst the grout is still mobile, by running a profiling tool along the joint to displace the surface of the grout.

The grout composition of the invention after mixing may be applied in any suitable way. The use of a long-handled squeegee for spreading the grout composition after it has been poured onto the tiles has been found to be effective- The grout composition having a low viscosity can easily flow into the joints, penetrating the whole joint to provide a solid grout

joint with an absence of air voids.

The first component of the grout composition of the invention preferably comprises epoxy resin of the Bisphenol type, such as a Bisphenol A resin or a Bisphenol A -J- F resin. The resin may be modified and may contain a reactive or non-reactive diluent such as an ether, for example, glycidyl ether. The resin component may also comprise one or more additives selected from defoaming agents _τ degassing agents and accelerators.

The second component of the grout composition of the invention contains a hardener for the epoxy resin. Examples of suitable hardeners for the epoxy resin include amines, amidoamines and polyamides. Preferred amines include aliphatic amines and cycloaliphatic amines. The latter may be more suitable when the grout composition is pigmented.

Other ingredients of the second component may include lightweight substances that are better mixed with a liquid component rather than with filler, in order to obtain substantially even dispersion throughout the grout composition when all the components are mixed together-

Lightweight substances suitable for inclusion in the second component may include thixotropic agents, such as fumed silica. It mav also be desirable to

include in the second component an air release agent such as a mixture of hydrophobic substances in a paraffin based mineral oil.

The third component of the grout composition of the invention is the filler, which may be one or a mixture of suitable fillers. The filler chosen is preferably chemically resistant. Mixtures of fillers may be used, such as for example a mixture of coarse and fine fillers. Examples of suitable fillers for the grout composition of the invention include silicas, calcites, limestones, magnesites, gypsum, talc and clays. Silicas are preferred. Fine fillers are preferably always used in combination with a coarse filler. Preferred coarse fillers have particle sizes in the range of 125 to 1000 microns. Preferred fine fillers have particle size in the range of 5 to 150 microns.

The grout composition of the invention may be pigmented by addition of pigment or dye to any component of the composition. Suitable pigments include titanium dioxide for white,, iron oxides for various colours and carbon black for black.

Fire retardant materials may be added to any component of the grout composition of the invention and include, for example, alumina trihydrate and hydrated magnesium calcium carbonate.

The ratio of epoxy resin to hardener in the composition of the invention will preferably be such as to obtain substantially complete curing of the epoxy resin and so the desirable ratio will depend on the resin. Typically for a Bisphenol A resin with an aliphatic a ine hardener the ratio of resin to hardener will be about 1.8:1. The amount of filler will preferably be in the ratio to hardener of between 4:1 τ.o 7:1, especially from 4:1 to 5:1. This invention will now be further described, by way of example only, with reference to the accompanying drawing which shows a tool 10 for use in shaping grout joints, for example, between cushion edge tiles or to produce a slightly recessed joint. The tool 10 comprises a handle 12 having at one end 14 a first bore 16 for a rod 18 on the end of which is a shaped tip 20 for profiling grout joint material and a second screw threaded bore 22 for a screw 24 which intercepts the first bore. By withdrawing the screw 24, the position of the tip 20 can be adjusted up or down relative to the handle and the screw then tightened against the rod 18.

The tool is used by running the tip 20 along grout joints to displace the surface of the grout while it is still mobile. The invention will now be further described with reference to the following Examples.

EXAMPLE 1 A grout composition for use in grouting a tiled floor following application of a protective wax layer (dispersion of paraffin wax in white spirit applied by lambswool roller) was made by mixing the following components just prior to application to the grout joints:

Component A

100.00 parts be weight Bisphenol A containing reactive diluent

Component B

50.00 parts by weight Modified aliphatic a ine 1.88 parts by weight Air release agent 1.13 parts by weight Fumed silica Component C

90.00 parts by weight Silica flour 135.00 parts by weight Silica sand The components were mixed thoroughly to give a grout composition having a viscosity of about 12,370 millipascals (spindle 5, 5 rpm) and the mixture poured onto the tiles and spread into the grout joints using a squeegee. Once the grout had cured, the protective wax layer was removed with the assistance of steam.

Because of the type of grout and its method of application it is possible for the grout to be more or less flush with the tile surface, so that the tiled

floor is easier to clean. The grout because of its low viscosity also completely fills the tile joints avoiding formation of air voids.

Example 2 A grout composition, for use in grouting a tiled floor, where the tiles have been fixed in a bed of suitable ceramic tile adhesive or cement-sand mortar, following application of a protective wax layer (dispersion of paraffin wax in white spirit applied by lambswool roller) or other suitable sealer, was made by mixing the following components just prior to application to the grout joints: Component A

100 parts by weight Bisphenol A epoxide resin 5 parts by weight reactive diluent

2 parts by weight epoxide accelerator 1 part by weight degassing additive Component B

50 parts by weight modified aliphatic amine Component C

150 parts by weight silica flour 150 parts by weight silica sand

The components were mixed thoroughly in a low shear mixer to give a grout composition having a viscosity of about 8,750 millipascals (spindle 5 5rpm

at 20 degrees centigrade ERV-8 viscometer) and minimum air-entrainment and the mixture poured onto the tiles and spread into the . grout joints using a squeegee removing most of the excess grout from the tile surface. Once the grout had cured, the protective wax layer was removed using steam and a metal scraper.

Because of the type of grout and its method of application it is possible for the grout to be more or less flush with the tile surface, so that the tiled floor is easier to clean. If a recessed joint is required then the grout is profiled whilst it is still mobile using a tool of the type illustrated in the accompanying drawing. The grout because of its low viscosity also completely fills the tile joints avoiding formation of air voids.