GB2497559A - A tile adhesive containing crushed glass - Google Patents

Abstract

A tile adhesive is disclosed, suitable for use in the repair of a tiled surface, where the adhesive comprises a viscous adhesive base with particulate matter (such as crushed glass having angular surfaces) distributed substantially evenly in the viscous adhesive base, the particulate matter being of maximum and minimum dimension in the range 0.1 to 2mm and importantly non-spherical and non-spheroidal in shape. Both a cementitious and a polymeric adhesive base are disclosed.

Description

Method of repairing a tiled surface and composition therefor The present invention relates to a method of repairing a tiled surface and composition therefore, in particular, the repairing of a limited number of tiles, such as isolated tiles in a surface which has previously been tiled.

The tiling of surfaces by the application of a plurality of tiles is a well-established practice. Tiling typically comprises the steps of preparing a sound and usually flat surface, applying to that surface a layer of adhesive and applying tiles to that adhesive. The adhesive may come in many forms such as a cementitious adhesive and application to the prepared surface of the adhesive is normally by means of a trowel. Use of a trowel with a castellated edge enables a layer of adhesive to be applied in ridges of constant thickness such that when a tile is applied the ridges of adhesive compress, and expand into intervening troughs, so as to accommodate variations in the tile and the wall, so that adjacent tiles may be attached with their outer surfaces substantially coplanar to give both an attractive and more easily maintained finish. For tiles attached to a vertical surface there is also the issue that tiles are normally attached with a significant gap between adjacent tiles. Since, for the reasons set out above, adhesive is normally applied in an initially pliable form the weight of a tile, particularly on a vertical surface will, due to gravity, usually make a tile sag under its own weight by deforming the adhesive and so move downwards, such as toward a vertically adjacent tile. This problem is normally overcome by the provision of tile edge and corner spacers, such as in the form of cross pieces inserted where adjacent corners of four neighbouring rectangular tiles in proximity to one another point together at a single focus, so as to maintain a constant distance and support upper tiles, via the spacer, from tiles below. After an adhesive is set a grout is typically applied in the gaps between the tiles so as to reduce the surface area of the tiled surface, stop the ingress of moisture and dirt between the tiles and to cover up the spacers. Whilst many forms of tiles are available the most commonly used, and the most relevant in the present disclosure, are ceramic tiles.

The above summary of known practice gives rise to, in particular, two problems: First, when a tiled surface has to be repaired, such as when an individual tile is broken or cracked the method of preparation where an adhesive layer of constant average thickness is applied with a castellated trowel is not practical. The damaged tile is typically extracted by removing the surrounding grout and breaking out the defective tile. This leaves a substantially uneven base of residual adhesive which is normally difficult to remove completely and evenly. The replacement of the defective tile is therefore problematic since a layer of adhesive of a given average thickness should be achieved but the castellated trowel application method is not really practical and a newly inserted tile must be pressed into the space (typically a recess between existing tiles) to a correct depth, whilst maintaining good adhesion. Pushing a tile in too deeply means that the tile must be removed and repositioned which is somewhat difficult due to suction and setting effects of the adhesive. Further, when laying a newly tiled wall the application of spacers is simple as spacers are applied above a lower layer so as to support an upper layer. However, when replacing isolated tiles or a group of isolated tiles, spacers are hard to fit and if of the correct dimensions mean that the new tile is a force fit into the space available. This s particularly difficult to do since the spacers should be of less thickness than the tile so that they may become subsequently covered by grout to hide them. The above considerations mean that replacing an isolated tile or group of tiles in a previously tiled surface is problematic and difficult to achieve with any degree of uniformity. This often leads to an uneven surface which can be harder to clean, maintain and otherwise attach objects over the tile (which may be a reason why a tile was damaged in the first place).

There is therefore a need for an improved method of attaching replacement tiles to a tiled surface wherein the problems associated with seating the tiles at a correct depth is made easier and more controllable and wherein the use of spacers is not required even on a vertical surface.

Second, it is becoming increasingly common to supply tiles in other than a regular square or rectangular format. For example, substantially rectangular tiles with a wavy edge, rounded corners, hexagonal tiles and other irregular shapes are becoming increasingly common. Whilst the motivation for using irregular shapes may be largely aesthetic this does not detract from the technical problem of applying those tiles evenly to a surface. The problem of locating tiles to a given depth is largely as discussed above for any type of tile. However, the provision of spacers, which as mentioned above, are normally applied at the intersection of joins of several tiles is often not practical with irregular tiles and even for regular shapes were the economics of manufacture mean that supply of spacers for, say, hexagonal tiles is uneconomic. Therefore, there is a need for a method and corresponding composition with which to apply tiles to a surface, particularly a vertical surface, in which use of a spacer insert between the ages of tiles is either not required or is minimised.

The present invention in its various aspects is as set out in the appended claims.

The present invention relates to a method of repairing a tiled surface, the method comprising the steps of: a. removing a tile from said tiled surface to create a space; b. removing surrounding grout and residual adhesive to an extent practical in the circumstances to enlarge that space; c. providing a replacement tile d. applying an adhesive into one or both of: i) the space created in steps a and b above; ii) the replacement tile e. placing the replacement tile into the space created in steps a and b such that the adhesive is sandwiched between the surface and the tile; wherein the adhesive comprises; i) a viscous adhesive base having a viscosity of greater than 200 Pa at a shear rate of 1 s ii) particulate matter distributed homogeneously in the viscous adhesive base, the particulate matter being: A. of maximum and minimum dimension in the range 0.1 to 2mm B. non-spherical and non-spheroidal It has been found that by the use of a tile adhesive of the defined viscosity and comprising offsetting particles of the particle size defined that to beneficial features are realised. In particular: i) That an inserted tile does not sag or slump or at least not substantially so (i.e. it retains its position on the surface), particularly when the principle plane of a flat tile is vertical and parallel to a vertical surface to which it is adhered by the composition.

ii) That when a tile is applied to the adhesive the degree of sag of the tile is much reduced or eliminated. The degree of sag depends upon the tile thickness, the tile weight and the thickness of the adhesive layer. However, when the adhesive is applied in a thickness of from ito 4mm (the thickness not being less than the minimum particle dimension then it has been found that substantially no sag is observed if the setting time of the basic adhesive is less than one hour. The setting time for the purposes of the invention is the time in which the adhesive composition doubles in viscosity.

Hi) That even with an uneven distribution of adhesive onto a surface, such as occurs when applied from a mastic gun is applied into a space where a replacement tile is to be applied (that space typically being a recess between existing tiles) substantially copular insertion of a replacement tile into an opening in an existing tiled surface is made much easier and more reliable.

Further, that a maximum distance of insertion of the inserted tile occurs so that even if the tile is pressed into deeply its subsequent removal for repositioning is more practical.

iv) That, unexpectedly, insertion of the tile into the adhesive requires in a first stage little force an in a subsequent second stage, occurring at about twice the particle size of the offsetting particles, more force is required wherein application of the tile is more easily controlled before the final maximum distance of insertion is achieved.

The adhesive is preferably placed upon the tile rather than on the surface or upon the surface and the tile. Placing the adhesive on the tile provides a more even base upon which to attempt to provide even distribution of the adhesive.

Particulate matter The particles for use in the present invention are non-spherical and non-spheroidal.

A spheroidal particle is a particle which is a distorted sphere and which has no corners. In practice, spherical and is for ideal particles supplied industrially often comprise the occasional broken particle. Hence, if this were of concern then provided that such particles comprised less than the required weight percentage of the total composition then such material would still not be suitable for the present invention. However, it is preferable that the only particles intentionally introduced into the composition are of a substantially similar geometry. An intentional combination of spheroidallspherical particles and angular particles is undesirable.

The particles are of maximum and minimum dimension in the range 0.1 to 2mm, preferably between 0.15 and 1.5mm, more preferably from 0.21 to 1.4mm, these figures representing 90% of the particulate material by weight retained on a sieve of the lower dimension and passing a sieve of the higher dimension.

The angularity of a particle can be determined by viewing particles under a microscope, the particles resting on a hard flat surface, such as a glass surface and lighting been arranged such that the particle can be seen as a silhouette.

When viewed in silhouette the particles of the present invention preferably disclose one flat side, the particles preferably disclose more than one flat side and even more preferably the flat sides are adjacent flat sides coming together to an actual or notional point where the sides intersect. Even more preferably, the particles comprise 3 or more flat sides and 2 or more points of intersection of those sides. A particle comprising a plurality of flat sides but no points between the sides is less preferable than a particle comprising points of intersection of flat sides. Particles comprising 6 or more flat sides are generally not preferred as these begin to approximate to spheroidal particles. At least one angle created by an actual or notional intersection of 2 adjacent flat sides is preferably 130° or less, preferably 90° or less, most preferably 10° or less. At least 2 angles are created by an actual or notional intersection of 2 adjacent flat sides is preferably 130° or less, preferably 90° or less, most preferably 70° or less. In the above considerations, the criteria are satisfied for the particles when 90% of the particles present in the relevant size range meet a particular criteria. Similarly, it can be said that if 90% of the particles, preferably 80% of the particles, more preferably 70% of the particles do not meet the criteria used to define the present invention then such a composition based on such particles may not be within the scope of the present invention. For example, provision of sufficient spherical particles can override the benefit of fewer, if otherwise adequate, angular particles.

For practical purposes it is usually immediately evident whether a particle is spherical, irregular but rounded or angular. However if that were to arise then a flat side of a particle is a side which comprises at least 10%, preferably at least 20%, most preferably at least 30% of the length of the circumference of the silhouette.

Similarly, particles which are platelets, i.e. have a minimum dimension less than a tenth of the maximum dimension are not considered particles for the purposes of the present invention, this naturally also including particles which are rods.

Also for practical purposes it is rare that commercially available material has perfectly flat sides when viewed in silhouette. Hence, for the purposes of the present invention a flat side is a side which approximates to a straight line deviating by not more than 10% of its total length from a notional straight line between endpoints of the side. In practice it is usually very easy to identify what looks like a straight side, the definition is merely presented to remove any ambiguity.

It has been found that by the use of irregular glass particles, those glass particles being derived from broken glass the ease of placement of a tile and pushing that tile so as to give a desired adhesive thickness and also the anti-sag property is much improved. The present invention therefore preferably employs irregular glass particles. The present invention therefore preferably employs glass particles derived from broken glass and preferably, that broken glass is not tumbled broken glass.

Investigation has shown that particular broken glass commercially supplied is tumbled, or treated to some similar process so as to remove sharp corners from the particles. Experiment has shown that such material does not correspond to a preferred material as determined by the above parameters. Tumbling is a process normally applied to broken glass so that a degree of rounding of sharp edges of the glass is removed.

Further, the preferred volume fraction of particles in the composition has been found to be in the range of from 5% by volume to 30% by volume, more preferably in the range from 10 to 25% by volume of the adhesive, most preferably from 15 to 20%.

This is particularly so when irregular broken glass particles are used, such as those of preferable geometry as previously defined.

Viscous Adhesive Base The viscous adhesive base, or base for short, is best defined by its physical characteristics. The base is required to be viscous as the particles/particulate matter alone is in itself insufficient to prevent a tile sagging under its own weight. The minimum viscosity required is 200 Pa at a shear rate of 1 5* As will be appreciated, a higher volume fill of particulate matter can compensate for a low viscosity of the base so as to provide a final composition of acceptable dispensing characteristics.

A maximum viscosity for the base composition is 1200 Pa at a shear rate of 1 5* A preferred viscosity range for the base composition is from 400Pa to 1 000Pa at a shear rate of 1 s-.

The viscosity is determined using a "Advanced Rheometer AR 2000". The software used was from TA Instruments, product version V5.7.0. The head geometry used was STD Steel Cone, Diameter -20mm, Angle -(deg:min:sec) 2:00:00, Truncation gap -58 micro meters.

Acceptable dispensing characteristics, which also provide acceptable viscosity characteristics for the purposes of stopping a tile sagging under its own weight when 2 mm to 5mm of adhesive is present on a standard tile (250 mm x 330 mm weighing 105g +1-5g) can be determined using an extrusion test as follows: Extrusion Test Method; 1. 1 50m1 of test material is filled (roughly 11 Og depending on the SG of the test material) into a cylinder, 70mm in length and 38mm in diameter, having at a first end wall having a central 4 mm diameter aperture and entering into an opposed end a piston having flat front and rear faces.

2. The material is extruded through the 4 mm diameter aperture by placing 30 psi air pressure into the opposed end of the cylinder and onto the piston, the person moving forward to extruded material.

3. The results are expressed as the weight of material extruded after 20 seconds.

Acceptable limits for results of the test are as follows:

Table 1.1

Extrusion (limits) (1) BOg -90g Extrudability unaffected compared to base material (No difference in ease of use) (2) 51g -Bog Extrudability negatively affected (More difficult to use) (3) 20g -51g Extrudability Severely affected (Extremely difficult to use) (4) 20g and below Extrudability affected un-gunnable (5) 90g and above Extrudability affected Too fluid Provision of a too viscous composition, such as a score of 3 in the table above, whilst potentially avoiding slump of the adhesive prevents the adhesive distorting sufficiently to adequately coat a tile, in which case a tile may simply fall off or to make it problematic to adequately level a tile compared to surrounding tiles potentially resulting in a tile cracking or incorrect outplacement.

For the purposes of the present invention provided that the base composition adheres to the particulate matter, that is that it has the property of wetting the service of the particulate matter then the particular chemistry of the composition so far as providing a solution to the problem addressed by the invention is not particularly significant. Hence, base compositions which are based upon aqueous polymer emulsions, nonaqueous polymer compositions and cementitious compositions are all envisaged.

A composition according to the present invention is preferably prepared first by preparing a base composition, as set out above. To this base composition are added particles. The advantage of adding angular particles to a pre-prepared base is that the preferred angular particles used in the present invention are relatively abrasive and minimising the mixing required reduces machine wear.

A suitable cementitious composition is as follows:

Table 2.1

Material Weight % Particulate matter 50% High Alumina Cement 6% Calcium Carbonate (fine ground) 5% Ordinary Portland Cement 30% Hydrated Lime (typically no bigger than 75p) 2.5% Polymer 5% Accelerator 0.1% Cellulose Thickener 0.5% Retarder 0.2% Fibre 0.5% Water To 100% A suitable aqueous polymeric base composition is as follows: An adhesive composition was prepared from the following components.

Table 2.2

Component % by weight Water 49.28 Dispex G40 0.79 Acticide BX 0.21 Actickie SW 0.21 Butyl Diglycol Acetate 1.27 Carbopol EZ1 0.79 Bermocoll E481 EQ 0.24 Attagel 30 0.01 AMP 95 0.31 Arbocel B400 2.36 Rhoximat Dec 27 34.29 WitcoYl5O78 1.02 Scotchlite KI 8.70 To the above composition was added glass particles at a level of 20 to 40% by weight, the composition is suitable for use in the method and the method when carried out with this composition provided a simple and convenient method of repairing a tiled surface with no slump or slippage of tiles even when tiles were placed on a vertical surface With no spacers/supports to original tiles.

Dispensing Adhesive for use in and of the present invention is preferably supplied in, and dispensed from, mastic cartridges. These are in the form of elongate cylinders having a first end with a nozzle and a second end with a moveable stopper, such as for use in a conventional mastic gun so as to exclude a cylinder of adhesive onto a surface, such as into the space mentioned above, the space implicitly having a backplane onto which the adhesive adheres. This method of application has been found advantageous in that the cylinders of adhesive applied to the surface enable the particles in the adhesive composition to readily rearrange so as to give rise to the above benefits of ease of insertion to a given depth and anti-sag.

The density of the preferred glass particles is: 2.7g/cm3. The preferred base density is 1.60g/cm3. The preferred compositions density is at 40% inclusion of particulate matter is 1.90g/cm3. Using these figures and equivalence between a preferred weight proportion of particulate matter and volume fill of that particulate matter can be established for the purposes of defining the present invention.

Evaluation of Product Characteristics As mentioned above, the benefits of the present invention arise because the composition provides adhesion without tile slippage. The test used for determining this property is the tile slip test.

The slip test is summarised in the following table:

Table 1.2

Tile Slip Test 1 Material must be easily hand applied through a 3- 4mm diameter aperture. Extrusion data must show a result above 20g, see extrusion test method.

Extrusion results below 20g will count as a fail.

2 A single perimeter bead is hand extruded through a 3-4mm diameter nozzle to a 250mm x 330mm tile __________________ (1050g ±5g) 3 The tile is firmly pressed against a vertical wall. Tiles are pushed against the wall, leaving a gap of no less than 2.0mm between the tile and the wall.

4 Vertical movement is measured once the tile is released.

Tile Slip Failure Criteria 1 Cannot be easily extruded though a 4mm diameter aperture using a hand skeleton gun [Extrusion result of less than 20g or below] 2 Tile Slips after being bonded to vertical plain (aQy downward movement after releasing tile). Movement greater than 0.5mm is classed as slip, and the test is observed for 30mm 3 Tile Falls from the vertical plain A suitable composition for practising the present invention preferably passes both the extrusion and tile slip tests.

The invention will now be illustrated by reference to the appended drawings in which: Figure 1 shows a tiled surface requiring repair; Figure 2 shows a tiled surface in the process of repair, a damage tile having been removed; Figure 3 shows a tiled surface in which a replacement tile is being placed upon adhesive; and Figure 4 shows a tile on a tiled surface illustrating the effects of tile sagging during adhesive setting.

Figure 5a and 5b show different views of particulate material suitable for use in the present invention, the material comprising 0.21mm -1.40mm Sieved Glass at 20x Magnification. The perimeter of the particles is considered a silhouette for the purposes of evaluating geometry.

Figure 6 shows particulate material in the form of glass spheres of diameter between 1.70mm and a 1.40mm which is unsuitable for use in the present invention.

Referring now to Figure 1 which shows a tiled surface 10 comprising a base 20 which would typically be a prepared surface of a wall of a structure that has been tiled. Upon the surface 20 are a plurality of tiles 30, one of which 32 has a defect 34.

The tiles are attached to the base by means of adhesive 40. In the illustration the adhesive is in a ridge and trough configurations, such as is typically achieved by application of adhesive using a castellated trowel. A repair process according to the present invention requires that the defective tile 32 is removed, such as by the use of percussion tools to (Figure 2) leave on damaged tiles 30 in place, remove the defective tile 32 and substantially remove residual adhesive 42. The residual adhesive 42 is typically uneven and/or the base 20 may also be damaged.

Subsequently in a known repair process fresh adhesive 44 is applied to the base 20 and any residual adhesive 42 present in and even a manner as possible, typically using a small trowel or similar applicator. Onto this adhesive is applied a replacement tile 36 and the tile is pressed towards the base so as to fill a gap between adjacent tiles 30. Insufficient pressure leaves the replacement tile 36 prominent, too great a pressure leads the replacement tile 36 depressed. The practicality of evenly applying fresh adhesive 44 typically means that the replacement tile 36 guards easily be applied so as to be coplanar with adjacent tiles 30, not least because tile edges cannot reasonably be gripped as spaces between the tiles 50 do not typically permit this. Further, so as to give and even spacing 50 around the tiles some lateral movement of the replacement tile 36 may be required, which exacerbates the problems of fixing the tile level.

Subsequent to a tiled being applied, and in particular on a vertical surface (Figure 4 A) the effect of gravity (illustrated by the arrow) causes the replacement tile 36 two distorts the fresh adhesive 44 such that the replacement tile distorts the fresh adhesive 44 and sags (Figure 4 B) such that even application of the tile is defeated.

Further, sagging, particularly on a vertical surface were movement occurs not only between the main faces of the replacement tile 36 and the base 20 but also perpendicular to those faces such that the tile edge 38 approaches any lower abutting surface 22. Hence, tile sag has two effects, removal of coplanarity between tiles but also the spacing between tiles and adjacent surfaces 22, such as another tile 30.

The method according to the present invention, when using a composition suitable for use in the method starts, as described earlier, in the situation is disclosed in figures 1 and 2. However, in a preferred embodiment of the invention the fresh adhesive 44 is applied using a cartridge, such as for use with a mastic gun, so as to exclude a continuous bead of fresh adhesive 44 onto the surface 20/42 onto which the replacement tile 36 is placed. This facilitates provision of a substantially uniform thickness of adhesive, albeit on an uneven surface.

The method according to the present invention further requires that a replacement tile is placed over the, preferably extruded, fresh adhesive 44 and the tile pressed towards the base 20. An adhesive according to the present invention, being an adhesive suitable for use in the method of the invention comprises an adhesive base and particular matter, in this example being termed offsetting particles.

Placing a tile 36 over such adhesive and pressing the tile towards the adhesive results in a series of increases in resistance by the adhesive to further movement.

After first contact, the adhesive mass flattens giving a first level of resistance, the offsetting particles then start to form bridges between the tile 36 and the base 20 providing a further level of assistance and, finally, a substantial number of particles act as bridges directly between the tile 36 and the base 20 preventing further inward movement. However, surprisingly, it has been found that the preferred diameter of offsetting particle is substantially smaller than the preferred gap-filling normally used for tile adhesives. In other words, a direct offsetting effect of the particles is not preferred as this has been found to give regular results since only between coplanar flat surfaces has an absolute offsetting, bridging, mechanical efficacy. In the present situation, between irregular surfaces, direct bridging is not an effective mechanism.

More surprisingly, when using angular offsetting particles it has been found that such particles even when not bridging between a tile 36 and a base 20 provide an anti--slump effect such that after a tile 36 is placed in position with adhesive 44 on a surface 20 the slump effect, even when using a relatively low base viscosity of adhesive 36, such that that's adhesive can be effectively extruded is achieved.

Hence, the present invention provides a method of using a composition, that composiflon being sufficiently low in viscosity for ready application, such as by extrusion, but by virtue of including offsetting particles, particularly angular offsetting particles, enables an anti-slump effect to being achieved.