Antimicrobial wipes and manufacture thereof

Abstract

A method of manufacturing an antimicrobial wipe comprising: providing a first sheet of textile material, applying a layer of particles of antimicrobial composition to the surface of the sheet, the com

Description

This invention relates to antimicrobial wipes, particularly but not exclusively, sporicidal wipes and to a method of manufacture thereof. Wipes of this invention find application for cleaning and disinfection of surfaces in healthcare environments, particularly with a high level or sporicidal, virucidal, bactericidal, fungicidal and yeasticidal efficiency in accordance with the applicable UK and international standards. WO 2016 / 055773 discloses disinfectant compositions which produce peracetic acid when added to water and which provide colour signals indicative of the concentration of peracetic acid. According to a first aspect of the present invention a method of manufacture of an antimicrobial wipe comprises the steps of: providing a first sheet of textile material; applying a layer of particles of an antimicrobial composition to the surface of the first sheet; covering the layer with a second textile sheet so that the layer of particles of the antimicrobial composition is located between the first and second sheets; wherein the antimicrobial composition comprises: a peroxy donor; an alkali component; an acid component; and a fusible material; applying a heated press to regions of the sheets to cause the fusible material to melt in said regions; allowing the regions to cool to cause the fusible material to solidify and bond the two sheets together to form a multi-layer composite structure. The layers of particles may be evenly distributed across the surface of the first sheet. The configuration of the regions may be selected to maintain an even distribution of the antimicrobial composition particles across the area of the wipe or wipes in use. Discrete regions may be configured so that some parts of the wipe are fused together with other parts having unfused particles contained within them. Alternatively, the entire surface of the wipe may be fused. The composition may have a particle size in the range of about 10pm to about 1600pm, for example about 200pm. In embodiments in which there are unfused particles of the antimicrobial composition, the particles may have a dimension greater than about 100pm in order to minimise or prevent losses of the antimicrobial composition through pores in the textile sheets prior to use. The sheets may be composed of woven or non-woven fabric. The fabrics may have a weight of about 20 to about lOOgm'2 and may be formed from biodegradable or compostable material. The fabric may be air laid or spun woven. The first and second sheets may be composed of the same or different materials, preferably the first and second sheets are composed of the same material. In an embodiment, a single larger sheet may be folded to form the first and second sheets. The sheets may be dimensioned to form single wipes or may be cut after bonding to form a plurality of individual wipes. The fusible composition may have a melting point in the range of 40°C to 180°C, preferably about 45°C to about 180°C, for example about 50°C. The amount of the fusible material may be in the range of about lwt% to about 50wt%, for example, about 15wt% to about 50wt%, typically about 40wt%. The fusible material may be an adhesive or surfactant. The fusible material may be selected from the group consisting of: fatty alcohols, ethoxylated fatty alcohols and mixtures thereof. These compounds may serve as an adhesive and / or surfactant. The fusible materials may be bio-based, compostable and made from raw materials from natural resources. One or more ethoxylated fatty alcohols may be employed, for example ethoxylated cetearyl alcohols such as for example as manufactured under the trade names Ceteareth 25, Ceteareth 20 or a polyethylene ether or lauryl alcohol, such as Laureth 25. Use of ethoxylated fatty alcohols in comparison to conventional thermoplastic adhesives provides the advantage that they are capable of fusing the substrate and powder together. These fusible materials are water-soluble so that the powder is not trapped on the wipe. The solubility of the formulation is increased and the wettability and cleaning properties of the wipe are also increased. Alternatively, or in addition, one or more fatty alcohols having a chain length of Ci6 to Ci8 may be employed, for example selected from the group consisting of lauryl alcohol, cetyl alcohol, stearyl alcohol and mixtures thereof. The peroxy donor may be selected from sodium percarbonate, sodium perborate and hydrates thereof, sodium persulphate and mixtures thereof. The amount of the peroxy donor may be in the range of about 20wt% to about 50wt%, for example, about 30wt% to about 40wt%, typically about 35wt%. The alkali component may be selected from: sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and mixtures thereof. The amount of the alkali component may be selected from about 10wt% to about 25wt%, for example, about 15wt% to about 20wt%, typically about 18wt%. The acid component may be selected from: adipic acid, citric acid, sodium bisulphate, sulphamic acid, tartaric acid or lactic acid, preferably adipic acid, citric acid and mixtures thereof. Citric acid is the most preferred as it may improve the fusible properties of the composition and may also act as a chelant to improve the rate of peracetic acid generation in hard and soft water. The amount of the acid component may be in the range of about 10wt% to about 25wt%, for example, about 15wt% to about 20wt%, typically about 18wt%. The heated press may be configured to apply heat and pressure to the whole of the wipe in order to fuse the whole of the upper and lower sheets together. The heat and pressure may be applied uniformly across the sheets. In an embodiment, a heated press may be configured to apply heat and pressure to selected regions of the sheet, for example to the periphery of the wipe to enclose the whole wipe. Alternatively, or in addition, the press may have raised members which may have a pattern, for example, a repeating pattern, to enclose discrete portions of the antimicrobial composition disposed on the first sheet. The press may comprise one or more rollers with raised ribs or ridges on the cylindrical surface. The rollers may be electrically heated. For example, the heated press may have a repeating hexagonal configuration in order to form hexagonal enclosures between the first and second sheets. In an alternative embodiment a heated press may apply heat and pressure to the entire surface of the wipe, so that all of the fusible material is melted to fuse together the entire surfaces of the sheets. The first and second sheets may comprise separate textile sheets which may be supplied from respective rolls during manufacture. Alternatively, a single double sized roll may be employed to provide a double sized sheet which is folded during manufacture to form a double layered structure. The press may comprise one or more heated rollers, for example, a pair of electrically heated rollers, arranged to form a nip through which the sheets may pass to cause melting of the fusible material and bonding of the upper and lower sheets. Preferably the press is heated on both the upper and lower sides of the sheets in use. Alternatively, the press may be moveable toward and away from the sheets to stamp the sheets together. The textile materials may be the same or different. One layer, for example, the lower layer in use of the wipe, may have an abrasive surface or abrasive regions. The upper surface of the wipe may be impermeable. According to a second aspect of the present invention, an antimicrobial wipe comprises first and second sheets of a textile material and a layer of a fusible antimicrobial composition located between the sheet, selected regions of the composition being fused to form one or more compartments between the sheets, each compartment containing a quantity of unfused antimicrobial composition; wherein the antimicrobial composition comprises: a peroxy donor; an alkali component; an acid component; and a fusible material. The components of the composition may be as disclosed above in relation to the first aspect of this invention. A wipe in accordance with the present invention has several advantages in comparison with previously available wipes. The wipe may generate a concentration of 4,000ppm of peracetic acid within 30 seconds of being contacted with water and may maintain sporicidal efficiency for a period of longer than 10 minutes, up to one hour, two hours or longer. The enclosures between the sheets serve to maintain the antimicrobial composition in situ between the 5 sheets during use of the wipe, so that the concentrated solution absorbed by the textile layers and any undissolved solid composition remains in the correct location and is evenly distributed across the wipe in use. The use of the fusible material confers several advantages. In addition to acting 10 as an adhesive, the efficacy of the composition is improved, particularly against fungi, yeasts and moulds. Also, penetration of the soil on the surface to be cleaned is improved. Exemplary compositions comprise the following ingredients. 15 Composition 1 Ingredient Amount / wt % Sodium carbonate 10-18 Adipic acid 8-16 Sodium dodecyl benzene sulphonate (SDBS 80) 0.5 - 1.0 Precipitated silica (Sipernat 22) 0.3-0.7 Ceteareth-25 25-50 Trisodium Citrate 1.00-2.5 Sodium Percarbonate 10-25 Tetraacetylethylenediamine 10-25 Composition 2 Ingredient Amount / wt % Sodium carbonate 10-18 Citric acid 8-12 Sodium dodecyl benzene sulphonate (SDBS 80) 0.5 - 1.0 Precipitated silica (Sipernat 22) 0.3-0.7 Laureth-25 25-50 Trisodium Citrate 1.00-2.5 Sodium Per carb onate 10-25 Tetraacetylethylenediamine 10-25 The fusible material of this invention has the advantage that it may increase the cleaning properties of the wipe. The fusible material is water soluble so that the biocidal material is not trapped in use. The fusible material has the further advantage of being flexible and not brittle and therefore serves to hold the sheets together when they are grasped in use. All the components are biodegradable. The wipe may attain a peracetic acid concentration of 4,000ppm in use. Percentages and amounts referred to in the specification are by weight and are selected from any ranges quoted to total 100%. The invention is further described by means of example, but not in any limitative sense with reference to the accompanying drawings of which: Figure lisa diagrammatic representation of a continuous manufacturing process in accordance with the present invention; and Figure 2 is an alternative manufacturing process in accordance with this invention. Example 1 An antimicrobial composition having the following ingredients was prepared as follows: Ingredient Amount / wt % Sodium carbonate 14.5 Adipic acid 12.8 Sodium dodecyl benzene sulphonate (SDBS 80) 1 Precipitated silica (Sipemat 22) 0.7 Ceteareth-25 40 Trisodium Citrate 1 Sodium Percarbonate 15 Tetraacetylethylenediamine 15 Example 2 An antimicrobial composition having the following ingredients was prepared as follows: Ingredient Amount / wt % Sodium carbonate 7.3 Citric acid 5 Sodium dodecyl benzene sulphonate (SDBS 80) 1 Precipitated silica (Sipemat 22) 0.7 Laureth-25 50 Trisodium Citrate 1 Sodium Percarbonate 20 Tetraacetylethylenediamine 15 Example 3 Figure lisa diagrammatic illustration of apparatus for manufacture of wipes in accordance with this invention. Fabric for the first layer (2) is fed from a first roll (1) onto a conveyor (3). The antimicrobial blend (4) is deposited onto the first layer from a reservoir (5). A second fabric layer (8) is supplied from a second roll (9) onto the antimicrobial composition layers (4, 6) disposed on the first fabric layer (2). The combined textile layers and powder composition are fed between a heated roller (10) and the conveyor (3), the conveyor (3) being supported by a lower roller (12) in order to allow pressure from the first roller to improve adhesion between the two fabric layers. A further roller (11) applies pressure to the combined fabric layers (13) to improve the adhesion between the two fabric layers. The dual layer wipe assembly (14) may be taken up onto a storage roller, not shown, or may be cut into individual wipes for packaging and distribution. Example 4 In use of a wipe manufactured as described in Example 2, the wipe may be wetted, for example by running under a tap or immersion in water and allowed to stand for a short period of a few seconds. The concentration of peracetic acid was as follows: Time / Minutes Concentration / ppm 0 0 0.5 4,160 10 9,900 15 10,700 This data shows that the sporicidal concentration of 4000 ppm is met by the wipe within 30 seconds, and the concentration exceeds this, demonstrating that the wipe will maintain its sporicidal efficacy for 15 minutes. The bio-based hot melt adhesive can be used to seal the edges of the wipe. This in combination with the other fusible material (the non-ionic surfactant) produces a wipe with improved wipe flexibility and structural integrity. It also provides a more cosmetically aesthetic appearance to the wipe, therefore improving the end user’s experience with the product. It does not however change the generation of peracetic acid produced by the wipe upon wetting. Example 5 Figure 2 shows a further embodiment similar to that of Figure 1 except that the heated roller assembly is replaced with a heated stamping press (26). The press (26) has a contact surface with a raised pattern (27) to produce a correspondingly configured pattern of zones of adhesion between the two fabric layers. The press (26) may also include cutter blades, not shown, to cut the assembly into individual wipes for packaging and transportation.

Claims

1. A method of manufacture of an antimicrobial wipe comprising the steps of: providing a first sheet of textile material;applying a layer of particles of an antimicrobial composition to the surface of the first sheet;covering the layer with a second textile sheet so that the layer of particles of the antimicrobial composition is located between the first and second sheets;wherein the antimicrobial composition comprises:a peroxy donor;an alkali component;an acid component; anda fusible material;applying a heated press to regions of the sheets to cause the fusible material to melt in said regions;allowing the regions to cool to cause the fusible material to solidify and bond the two sheets together to form a multi-layer composite structure.

2. A method as claimed in claim 1, wherein the fusible material has a melting point in the range 50°C to 180°C.

3. A method as claimed in claim 1 or 2, wherein the amount of the fusible material is in the range of 1 wt% to 50 wt%.

4. A method as claimed in claim 3, wherein the amount of the fusible material is in the range of 15 wt% to 50 wt%.

5. A method as claimed in any preceding claim, wherein the fusible material is selected from the group consisting of: fatty alcohols, ethoxylated fatty alcohols and mixtures thereof.

6. A method as claimed in claim 5, wherein the fusible material is an ethoxylated fatty alcohol.

7. A method as claimed in claim 6, wherein the fusible material is selected from the group consisting of: ethoxylated ceteryl alcohols, lauryl polyethylene ethers and mixtures thereof.

8. A method as claimed in any preceding claim, wherein the fusible material is a fatty alcohol having a chain length of Ci6 to Cis.

9. A method as claimed in any preceding claim, wherein the peroxy donor is selected from the group consisting of: sodium percarbonate, sodium perborate and hydrates thereof, sodium persulphate and mixtures thereof.

10. A method as claimed in claim 9, wherein the amount of the peroxy donor is in the range of 20 wt% to 50 wt%.

11. A method as claimed in claim 10. Wherein the amount of the peroxy donor is in the range of 30 wt% to 40 wt%.

12. A method as claimed in any preceding claim, wherein the alkali compound is selected from the group consisting of: sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate and mixtures thereof.

13. A method as claimed in claim 12, wherein the amount of the alkali compound is in the range of 10 wt% to 25 wt%.

14. A method as claimed in claim 13, wherein the amount of the alkali component is in the range of 15 wt% to 20 wt%.

15. A method as claimed in any preceding claim, wherein the acid component is selected from the group consisting of: adipic acid, citric acid, sodiumbisulphate, sulphamic acid, tartaric acid, lactic acid and mixtures thereof.

16. A method as claimed in claim 15, wherein the amount of the acid component is in the range of 10wt% to 25wt%.

17. A method as claimed in claim 16, wherein the amount of the acid component is in the range of 15wt% to 20wt%.

18. A method as claimed in any preceding claim, wherein the regions enclose discrete portions of the wipe within which the composition is not melted during manufacture.

19. An antimicrobial wipe comprising first and second sheets of a textile material and a layer of a fusible antimicrobial composition located between the sheet, selected regions of the composition being fused to form one or more compartments between the sheets, each compartment containing a quantity of unfused antimicrobial composition;wherein the antimicrobial composition comprises:a peroxy donor;an alkali component;an acid component; anda fusible material;made by the method of any preceding claim.

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