ANTI-MICROBIAL CLEANING AID

DESCRIPTION

TECHNICAL FIELD

The invention relates to an anti-microbial cleaning aid and a method of making the same. The anti-microbial cleaning aid may include an abrading material for use, for example, in the manufacture of scouring pads and/or cloths with enhanced resistance to culturing bacteria including MRSA and C. difficile. Background Art

GB-B-2157329 discloses a method of making an abrading sheet material which comprises knitting a ground structure from a mixture of a polyester and a heat shrinkable PVC yarn with laid-in floated threads of a second material of polyester which is harder than and either non-shrinkable or less shrinkable than the ground structure materials,

then shrinking the ground structure so that loops of the second material are raised from a surface thereof .

WO-A- 9719211 discloses a method of making an abrading material which comprises knitting a ground structure comprising a heat shrinkable polyolefin yarn with laid- in looped threads of a hard material, such that the looped threads are raised from a surface of the ground structure, and shrinking the shrinkable yarn of the ground structure to grip the looped threads to lock the loops in place in the ground structure.

Materials made in accordance with GB-B-2157329 and WO-A- 9719211 provide good abrading properties but do not defend against MRSA and associated culturing bacteria adequately. It is an object of the invention to provide a cleaning aid, perhaps with an abrading surface, which is relatively inexpensive to manufacture and which may offer a much higher degree of protection against MRSA and associated culturing bacteria. DISCLOSURE OF INVENTION

Aspects of the invention are defined in the appendant independent claims to which reference should now be made. Embodiments of the invention are defined in the appendant dependent claims to which reference should also now be made.

In accordance with one aspect of the present invention, there is provided a method of making an antimicrobial cleaning aid, comprising: knitting a ground

structure comprising a shrinkable yarn with laid- in looped threads of a hard material, such that the looped threads are raised from a surface of the ground structure; and shrinking the shrinkable yarn of the ground structure to grip the looped threads to lock the loops in place in the ground structure; characterized in that the ground structure comprises a copper yarn.

For the purposes of the present specification, the copper yarn may comprise or consist of a single or multi- stranded wire of substantially pure copper (e.g. at least 95% by weight copper) or a wire or strand of a high-copper alloy such as brass. The high copper alloy may comprise at least 50% by weight copper, perhaps even at least 60% by weight copper. The anti-microbial properties of copper and high-copper alloys are well known. In hospitals, frequently touched surfaces such as door handles and push plates made of copper and high copper alloys are being used to help prevent the spread of infections by touch in an effort to reduce hospital-acquired infections. The present applicant has found that the presence of copper yarn in the ground structure may help to inhibit the growth of harmful pathogens in cleaning products. Thus, such cleaning products made in accordance with the present invention may help to prevent the spread of bacteria from one surface to another by contact when the surfaces are being cleaned.

The copper yarn has a denier or thickness suitable for knitting into the ground structure. For example, the

copper yarn may have a thickness of less than 0.50mm (5.0xl0 ^'4 m) . Furthermore, the copper yarn may have a thickness greater than 0.050mm (5.0xl0 ^~5 m) . For example, the copper yarn may have a thickness of about 0.10mm (1.0xl0 ^'4 m) .

The copper yarn may be arranged in substantially parallel courses or lines in the ground structure (at least when positioned unstretched on a planar substrate) .

The parallel lines may be regularly spaced across the ground structure. The spacing may be in the range from

0.10mm (l.OxlO ^' V) to 10cm (1. OxIO^m) , perhaps from 0.50mm

(5.0xl0 ^~4 m) to 5.0cm (5.0xl0 ^"2 m), or perhaps even from 1.0mm

(1.0xl0 ^'3 m) to 5.0mm (5.0xl0 ^'3 m) . The preferred spacing between adjacent pairs of parallel lines of copper yarn may depend, at least in part, on the thickness of the copper yarn. For example, for a copper yarn with a thickness of 0.10mm (1.0xl0 ^"4 m), the spacing may be as little as 0.20mm (2.0xl0 ^'4 m) .

The shrinkable yarn may be a polyolefin yarn. The shrinkable yarn may be a PVC yarn, but a polyolefin yarn is preferred. The looped threads are preferably of a material which is harder than the shrinkable yarn of the ground structure .

Preferably the shrinkable yarn is heat shrinkable, and preferably the method of making the anti-microbial cleaning aid comprises the step of heat treating the ground structure so that the shrinkable yarn in the ground structure contracts to grip the looped threads to lock the

loops in place. The heat shrinking properties of the shrinkable yarn are preferably controlled by subjecting the yarn to a pre-treatment process, known per se, which consists of nipping the yarn at intervals along its length under pressure and at a temperature above it heat shrinking temperature .

When the material is heated with the looped threads raised from the surface of the ground structure, the shrinkable yarn of the ground structure grips the looped threads to lock the loops in place in the ground structure. The copper yarn of ground structure is also held by the shrinkable yarn.

Preferably the ground structure further comprises a yarn which is substantially non heat shrinkable or which is less heat shrinkable than the shrinkable yarn, e.g. polyester yarn.

Preferably the looped threads are of polyester. The looped threads maybe of a yarn or tape made by cutting a synthetic polyester film such as that sold under the registered trademark 'Mylar' . It would be appreciated however that other abrasive tapes or yarns maybe utilised.

The method may further comprise the step of restraining the ground structure against shrinkage during heat treatment so that the shrinkable yarn in the ground structure contracts to lock the loops in place.

During the knitting process the looped forming material will preferably be positively feed through the knitting machine to form the loops, rather than being held

under tension during knitting.

The method may further comprise securing the ground structure to or around an absorbent member (e.g. a pad of resilient thermoplastic material or a cotton cloth) . The absorbent member may comprise copper. In this way, the anti-microbial properties of copper may be able to act upon fluids absorbed by the absorbent member. The absorbent member may comprise a copper wire (e.g. a single or multi-strand wire of substantially pure copper or a high-copper alloy) . The copper wire may have a thickness of less than 0.50mm (5.0xl0 ^~4 m), and may have a thickness greater than 0.050mm (5.0xl0 ^~5 m) . For example, the copper wire may have a thickness of about 0.10mm (1.0xl0 ^"4 m) . The copper wire may be arranged in lines (e.g. parallel lines) in or on the absorbent member, and such parallel lines may be regularly spaced across the absorbent member. For example, the spacing may be in the range from 0.10mm (1.0xl0 ^"4 m) to 10cm (1. OxIO^m) , perhaps from 0.50mm (5.0xl0 ^~4 m) to 5.0cm (5.0xl0 ^'2 m), or perhaps even from 1.0mm (1.0xl0 ^~3 m) to 5.0mm (5.0xl0 ^~3 m) . The parallel lines of copper wire in the absorbent member may be arranged transversely to any parallel lines of copper yarn in the ground structure so as to form a grid- like array. The spacing between parallel lines of copper wire in the absorbent member and the spacing between parallel lines of copper yarn in the ground structure may be the same or different. The grid-like array may be orthogonal, and may define rectangles or squares in between the parallel lines

of copper wire and yarn.

The step of securing the ground structure to or around the absorbent member may comprise sewing, using adhesives, welding or heat bonding. If sewing, a copper wire may be used to stitch the ground structure to or around the absorbent member. The copper wire may be in electrical contact with the copper yarn in one or more positions .

The absorbent member may comprise a resilient thermoplastic material, such as polyurethane foam. Alternatively or additionally, the absorbent member may comprise a cloth of natural fibres (e.g. cotton) or man- made fibres. The cloth may comprise at least two layers, with the copper wire sandwiched therebetween. In accordance with another aspect of the present invention, there is provided an anti-microbial cleaning aid comprising a sheet of abrading material comprising a knitted ground structure with looped threads raised from a surface of the ground structure, the ground structure comprising copper yarn. The looped threads may be locked in place in the ground structure by a shrunken yarn, e.g. a polyolefin yarn. The ground structure may further comprise another yarn which is substantially non- shrinkable or which is less shrinkable than the shrunken yarn. The another yarn may be polyester. The percentage relation of ends of the another yarn (e.g. polyester) and ends of copper yarn may be from 1% to 75%, perhaps 5% to 50%, possibly even 40%.

In accordance with another aspect of the present invention, there is provided an anti-microbial cleaning aid comprising an absorbent body for absorbing liquids during cleaning, characterised in that at least one strand of copper wire is disposed in or on the absorbent body. The at least one strand of copper wire may be arranged in a plurality of parallel lines in or on the absorbent body, and such parallel lines may be regularly spaced across or through the absorbent body. The dimensions of the at least one strand of copper wire may be the same as those for the copper yarn of the first aspect of the invention. The spacings of the parallel lines may be the same as those for the copper yarn of the first aspect of the invention. The absorbent body may be of the same material as the absorbent member of the first aspect of the invention.

Antimicrobial properties may be exhibited by other metals such as silver and possibly zinc. Thus, the present applicants believe it may be possible to replace the copper in the preceding statements with certain other metals, such as silver or zinc, and still have a viable antimicrobial cleaning aid. BRIEF DESCRIPTION OF DRAWINGS

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a pattern illustrating how an abrading material of an anti-microbial cleaning aid in accordance

with one embodiment of the invention is knitted;

Figure 2 is a perspective view illustrating the top or working surface of the abrading material of Figure 1;

Figure 3 is a side view of an anti-microbial cleaning aid in accordance with another embodiment of the present invention;

Figure 4 is a side view of an anti-microbial cleaning aid in accordance with yet another embodiment of the present invention; Figure 5 is a side view of yet another anti-microbial cleaning aid embodying the present invention; and

Figure 6 is a schematic illustration showing construction details of the anti-microbial cleaning aid of Figure 5. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

A ground structure of an abrading sheet material is knitted according to the pattern of Fig.l in which the ^λ x' lines indicate courses of heat shrinkable polyolefin yarn and the *+' lines indicate course of alternate polyester and copper yarn. However the percentage relation of ends of polyester and copper in the ' + ' lines could vary by economic choice from 1% to 75%, suitably 5% to 50% though preferably the standard production of the material will probably be 40%. The percentage calculation is based upon Fig 1. ' + ' lines where the copper substitutes the polyester to the desired percentage. During knitting polyester yarn e.g. that sold under the registered trademark 'Mylar' in the form of cut tape is laid in,

being tucked to each fourth stitch of polyolefin yarn across the courses, the tucks ^λ o' of alternative threads of polyester tape having a walewise staggered relationship so that the loops of polyester tape are not in alignment in the direction of the wales of the fabric . The polyester tape is positively threaded through the knitting machine such that the loops are formed above the ground structure .

Figure 2 diagrammatically illustrates the top surface of the fabric 10 after it has been knitted. It will be seen that the loops 12 of polyester tape stand up from the ground structure 14. The fabric 10 is now subjected to heat treatment while the opposed edges of the ground structure are held to prevent shrinkage so that the polyolefin yarn of the ground structure shrinks or sets to lock the loops 12 in the ground structure.

Figure 3 illustrates one use of the resulting abrading sheet material 10 of Figures 1 and 2 in an antimicrobial scouring pad 20. A suitably sized piece of the abrading sheet material 10 is secured (e.g. by impulse heat welding) to a pad of resilient thermoplastic material 22 {e.g. polyurethane foam), with the loops 12 exposed over one surface thereof. The opposing surface of the pad of resilient thermoplastic material 22 is covered by a foamed cellulosic layer 24 to form a wiping surface . Figure 4 illustrates another use of the resulting abrading sheet material 10 of Figures 1 and 2 in a universal anti-microbial scouring pad 30. The abrading sheet material 10 is provided in a sock format with loops

12 on the outer periphery, and is filled with a resilient thermoplastic material 32. The open ends 34 are then sealed for example by heat bending, welding adhesives or sewing (e.g. with copper wire) .

5 Figure 5 illustrates an anti-microbial cleaning scourer 40, which is similar to the scouring pad 20 of Figure 2, but without the resilient thermoplastic material 22. Thus, in anti-microbial cleaning scourer 40, the abrading sheet material 10 is secured to a backing layer

10 42, for example a foamed cellulosic layer. The abrading sheet material 10 has parallel lines 44 of copper yarn in its ground structure 12, represented schematically in (a) of Figure 6. The backing layer 42 also has parallel lines 46 of copper wire, represented schematically in (b) and

15 (c) of Figure 6. The spacing between the parallel lines of copper yarn in the ground structure 12 is less than the spacing between the parallel lines of copper wire in the backing layer 42. Before assembled together, the backing layer 42 is rotated relative to the abrading sheet

20 material 10 so that the parallel lines 44 and 46 form a grid when registered, as shown schematically in (d) of Figure 6.

Comparative Testing Two cleaning aids were provided for testing:

25 a) an abrading sheet material in accordance with WO97/19211 (without copper) with a cotton cloth backing; and b) abrading sheet material in accordance with Figures

1 and 2 (with copper yarn approximately 0. lmm thick and spaced on average 2.86mm apart) with a cotton cloth backing .

Each of these samples were cut into 2.5cm squares and placed individually in a sterile Petri dish. Sample (b) was cut to include a uniform number of copper threads in each sample . Each sample was inoculated with 0.5 ml of test organism. This was sufficient to wet the whole of the sample. The samples were placed rough side up to aid absorption of the fluid. The samples were tested to determine colony forming units per millilitre (cfu/ml) at the following time intervals (mins) 0, 5, 30, 60, and 120, and also after 24 hours. Sufficient numbers of samples were used to test each time interval in duplicate and two blanks. The organisms used were Staph, aureus NCIMB 9575 (6300/ml) and Pseudomonas aeruginosa NCIMB 8626 (4000/ml) , representing Gram-Positive and Gram-Negative kinds of bacteria.

Each sample was placed into 9.5ml of sodium chloride peptone (SCP) (-1 dilution) and mixed using a vortex. This was then further diluted 1 in 10 (-2) . ImI samples of each dilution were cultured using a tryptone soya agar (TSA) . Plates were incubated at 30 ⁰ C for two days. The results are set out in Table 1 and notably for sample (b) the level of:

Staph, aureaus NCIMB 9575 (initially 6300/ml) is down to

310/ml after 24 hours, a reduction of 95%.

Pseudomonos aeruginosa NCIMB 8626 (initially 4000/ml) is

down to 150/ml after 24 hours, a reduction of 96.25%.

It is believed that a cloth scourer 40 as described with reference to Figures 5 and 6 may achieve a 99% reduction of organisms.

TABLE 1

Time Staph, aureus Ps. aeri

(Minutes) (cfu/ml) (cfu/

Sample (a) Cloth

(no Copper): 0 7500 1560

5 3900 1700

30 2130 1200

60 1990 750

120 1960 420

(24 hour) 1440 3580 3700

Start 6300 4000

% Decrease 43.2% 7.5%

Sample (b) Cloth

(with Copper): 0 2500 4600

5 2740 2550

30 2950 1380

60 5800 1140

120 1900 660

(24 hour) 1440 310 150

Start 6300 4000

% Decrease 95.1% 96.3%