Patent Application
20060286884
The present invention relates to wiping articles that are suitable for consumer use in cleaning surfaces in various environments, including domestic, industrial, hospital and food industry environments. The invention relates, in particular, to wiping articles that have a scouring surface (also called a scrubbing surface), on at least one side.
Wiping articles are already widely used by consumers in the environments mentioned above for cleaning, for example, kitchen and bathroom surfaces, including floors. Many different wiping articles are currently available for domestic use, ranging from paper towels to conventional textile dish cloths and floor cloths, some being intended to be used dry (for example, to mop-up spilt liquid) and others being intended to be used in a damp or wet condition. It is also known to provide wiping articles that have a scouring action suitable for removing hardened soil and stains from a surface to be cleaned.
Examples of wiping articles that have a scouring action are described in U.S. Pat. Nos. 4,142,334 and 5,213,588, and in EP-A-0 211 664. Each of those documents describes wiping articles that, on one surface, carry an ordered pattern of abrasive areas formed by a printing process using a dispersion of abrasive particles in a liquid adhesive or binding agent that is subsequently allowed or caused to solidify. Wiping articles that have a mild scouring action without the use of abrasive particles are also known: for example, a mild scouring action can be achieved by spraying one side of a wiping substrate with molten polymer fibres that are subsequently allowed to harden. Generally, however, the provision of spaced abrasive areas on a wiping substrate is preferred since it enables the flexibility of the substrate to be retained to a large extent and provides a wiping article that is easier for the consumer to handle and use.
The present invention provides a method of making a wiping article for cleaning surfaces, the method comprising the steps of
(i) providing a liquid-absorbent web material;
(ii) providing a dry particulate material that comprises at least particulate curable binder material;
(iii) depositing spaced areas of the dry particulate material on a liquid-absorbent surface of the web material; and
(iv) curing the binder material to form spaced abrasive areas on the surface of the web material, the said abrasive areas being spaced apart by liquid-absorbent areas of the web material The present invention also provides a wiping article for cleaning surfaces, comprising a liquid-absorbent web material and, disposed on a liquid-absorbent surface thereof, abrasive areas comprising at least cured particulate binder material, the said abrasive areas being spaced apart by liquid-absorbent areas of the web material.
By way of example only, wiping articles in accordance with the present invention, and methods of making those articles, will now be described with reference to the accompanying drawings, in which:
The present invention is directed to wiping articles that, at least on one surface, carry abrasive areas that provide the article with a scouring action, the remainder of the surface being available to provide the normal wiping action of the article. The present invention comprises a liquid-absorbent web material and, disposed on a liquid-absorbent surface thereof, abrasive areas comprising at least cured particulate binder material, the said abrasive areas being spaced apart by liquid-absorbent areas of the web material. As used herein, “particulate curable binder material” means a material that is solid at room temperature, has been processed to a particulate form, and which may be softened and cured either by heating and subsequent cooling (if thermoplastic) or by sufficient exposure to heat or other form of energy (if thermosetting or cross-linkable).
The invention is concerned with providing a method of making such wiping articles that has less environmental impact than methods that are currently employed. The use of a particulate binder material in a method in accordance with the invention enables the abrasive areas to be produced on the surface of the web material without producing volatile organic compounds (VOCs), and may also result in the energy requirements of the method being lower than those of methods that employ liquid binder materials.
In a further aspect, the invention is concerned with providing wiping articles of that type with an attractive visual appearance in addition to an effective scouring action. The use of a particulate binder material enables the binder material to be deposited on the web material under the action of an electrostatic force: that, in turn, makes it possible to produce well-defined abrasive areas on the web material in a wide variety of patterns and thus provide consumers with an attractive choice of products.
The wiping article 1 shown in
A method of making the wiping article 1 is illustrated diagrammatically in
Electrostatic spray guns are known from the powder coating art, where they are used in electrostatic powder coating systems to apply electrically-charged powder coating material to an electrically-grounded workpiece. A typical known electrostatic powder coating system consists of a powder hopper, a high voltage power supply (generating, for example, up to 100 kV), an electrostatic spray gun and a powder recovery system. The powder is fluidized in the hopper and then fed to the spray gun, which directs it towards the workpiece to be coated. An electrode at the front of the spray gun is connected to the power supply and causes an electrostatic charge to be imparted to the powder coating material as it is being propelled toward the grounded workpiece. The charge causes the powder particles to be drawn towards, and to attach themselves to, the grounded workpiece. Powder that is not deposited on the workpiece can be recovered and re-used.
In the method illustrated in
The web material 3 is then exposed to conditions that will cause the particulate binder material 15 to soften and then to cure, to bind the abrasive particles 14 in each of the spaced areas 5 to each other and to the surface 4 of the web material 3. In the process illustrated in
Using the method illustrated in
The abrasive areas 5 need not be of the form shown in
To ensure that the wiping article 1 retains an adequate wiping action and remains flexible and easy for the user to handle, the abrasive areas 5 should preferably not cover more than about 50% of the surface of the wipe material 3. If the abrasive areas cover a greater amount of the surface of the wipe material, the liquid-absorbency of the wiping article may be substantially reduced, as may the scouring performance since there will be an increasing tendency for the wiping article to slip on the surface that is being cleaned. Generally, it has been found that the best results are obtained when the abrasive areas 5 cover about 15-40% of the surface of the wipe material 3. The size of the individual abrasive areas 5 can vary depending on the way in which they are arranged on the surface of the wiping material but, if they are too large, the wiping article may slip on the surface to be cleaned and be less effective. In addition, the arrangement of the abrasive areas 5 on the surface of the wiping material 3 should preferably not be directional, to ensure that the user does not need to orient the wiping article 1 correctly before use.
In the particular case in which there is a single abrasive area 5 only on the surface of the wiping article, it is also preferred that it should cover no more than about 50% of the wiping surface of the article in such a way that the user can choose to utilize either the scouring or the liquid-absorbent area of the wiping article.
The powder coating booth 9 can be of any suitable type known for use in powder coating applications. The stencil 13 should preferably be non-conductive but can otherwise be of any suitable material provided that it can be moved into close contact with the surface 4 of the web material 3 and thereby ensure that the areas of particulate material 5 deposited on the web material are well-defined. The stencil 13 may, for example, be a textile belt (for example, a silk screen belt) or a belt of a polymeric material (for example, PVC, polyester, polyurethane, or polyamide).
It is not essential that the stencil 13 should be in the form of a continuous band as illustrated in
The amount of particulate material 14, 15 that is deposited on the web material can be adjusted by changing the speed at which the web material moves through the coating booth 9. It can also be adjusted by changing the number of spray guns 17 that are used in the booth or by altering the spray gun settings. By reducing the amount of particulate material 14, 15 deposited to a low level and, at the same time, omitting the stencil 13, a wiping article can be produced in which one surface will be covered with randomly-located particle-size abrasive locations spaced apart by liquid-absorbent areas of the web material. In that case also, the area of the abrasive locations should not be more than about 50% of the area of the wiping surface.
If high-definition is not required for the abrasive areas 5 on the web material 3, it is possible to form a general pattern for the abrasive areas in the surface provided underneath the web material by the electrically-conductive conveyor 11 and omit the stencil 13. For example, the conveyor 11 may be in the form of a grid, in which case the particulate material from the spray gun 17 will collect on the surface of the web material 3 preferentially along the grid lines of the conveyor. The grid lines will, however, not be well-defined and some particulate material will also be deposited on the web material in the spaces between the lines.
As a further alternative, suitable also if high-definition is not required for the abrasive areas 5 on the web material 3, a general pattern of abrasive areas can be formed by omitting the stencil 13 and using a web material 3 with a surface structure (e.g. a crepe material) that will result in some areas of the web material being in closer contact with the conveyor 11 than others. A greater amount of particulate material 14, 15 will be deposited on those areas of the web material that are in closest contact with the conveyor 11.
Other coating apparatus can be used, instead of the coating booth 9 with spray gun 17, to carry out the electrostatic deposition of the dry particulate material 14, 15 on the web material 3. These include, for example, apparatus in which the particulate material is aerated in a fluidizing chamber and electrostatically-charged by ionized air so that it will adhere to the web material. The web material with the particulate material adhered to it can then be passed to the oven 19 as described above.
If desired, the dry particulate material 14, 15 supplied from the hopper 16 to the electrostatic spray gun may include additives that are customary in the powder coating art, such as pigments, fillers, flow aids etc. Some of those additives, for example pigments and fillers, may be incorporated in the binder material particles.
The nature of the web material 3, and of the abrasive particles and particulate binder material that may be used in the process of
A) The Web Material
Any web material known to be suitable for use as a consumer wiping article can be used as the web material 3, provided that the surface of the material is sufficiently closed to ensure that neither the abrasive particles 14 nor the particulate binder material 15 can penetrate the web material 1 but will always remain on the surface. If the abrasive areas 5 are to be well-defined, the surface of the web material on which they are formed should also be smooth and flat enough to ensure close contact by the stencil 13 in the powder coating booth 9.
The web material 3 should be selected having regard to the intended use of the wiping article 1. Known wipe materials generally have a basis weight in the range of from 15 to 300 gm/m2, although materials having a higher basis weight could be used. Woven and knitted materials are suitable, as are non-woven materials including dry-laid, wet-laid and spun-bonded materials which may, as appropriate, be thermally-bonded, resin-bonded, ultrasonically-bonded, needle-punched, hydro-entangled etc. Wipe materials are often hydrophilic but can also be specifically constructed to absorb non-aqueous liquids, for example grease and oil. They are often categorized, depending on their durability, as “disposable” (meaning that a wiping article formed from the material is intended to be discarded immediately after use), “semi-disposable” (meaning that that a wiping article formed from the material can be washed and re-used a limited number of times), or “reusable” (meaning that a wiping article formed from the material is intended to be washed and re-used).
Disposable wipe materials suitable for use as the web material 3 include spun-bond and spun-lace non-woven materials having a basis weight in the range of from 15 to 75 g/m2 and formed, for example, from PET, rayon, viscose, wood pulp, polypropylene, natural fibres, polyamide or mixtures thereof. Examples of disposable wipe materials are available under the trade names: “Sontara” from DuPont; and “TenoLace” from Tenotex of Terno d'Isola, Italy.
Semi-disposable wipe materials suitable for use as the web material 3 include spun-lace non-woven materials having a basis weight in the range of from 75 to 250 g/m2 and formed, for example, from fibres or microfibres of polyester, polyamide, viscose. Examples of semi-disposable wipe materials are available under the trade names “Scotch-Brite™ Dusting Cloth” from 3M Company of St. Paul, Minn., USA; and “Sontara” from DuPont.
Reusable wipe materials suitable for use as the web material 3 include knitted, woven, thermo-bonded, latex-coated, and chamois-type materials having a basis weight in the range of from 100 to 300 g/m2 and formed, for example, from fibres or microfibres of PET, rayon, viscose, polypropylene, natural fibres, polyamnide or mixtures thereof. An example of a reusable wipe material is the material used for wipes available under the trade name “Cif” from Lever Fabergé, Switzerland.
B) The Particulate Binder Material
The particulate binder material 15 may be any suitable binder resin that is solid at room temperature and has been processed to particulate form, and should be selected having regard to the nature of the web material 3 on which it is to be deposited and its intended use in a domestic wiping material. The binder material should also be capable of being activated without damaging the web material. Depending on the intended use of the wiping article, the cured binder material may be required to be able to withstand washing and exposure to certain cleaning compositions. The particulate binder material 15 should also be of a size suitable for use in the electrostatic spray gun 17.
Suitable particulate binder materials include thermosetting and thermoplastic powders that are activated by heat, as well as powders that are activated other ways. Thermosetting resins from which the particulate binder material can be selected include formaldehyde-containing resins, such as phenol formaldehyde, novolac phenolics and especially those with added crosslinking agent (e.g., hexamethylenetetramine), phenoplasts, and aminoplasts; unsaturated polyester resins; vinyl ester resins; alkyd resins, allyl resins; furan resins; epoxies; polyurethanes; and polyimides. Thermoplastic resins from which the particulate binder material can be selected include polyolefin resins such as polyethylene and polypropylene; polyester and copolyester resins; vinyl resins such as poly(vinyl chloride) and vinyl chloride-vinyl acetate copolymers; polyvinyl butyral; cellulose acetate; acrylic resins including polyacrylic and acrylic copolymers such as acrylonitrile-styrene copolymers; and polyamides (e.g., hexamethylene adipamide, polycaprolactum), and copolyamides. Mixtures of the above thermosetting and thermoplastic resins may also be used.
Binder materials that are cured other than by heating or cooling can also be used, for example, materials that are cured by ultraviolet light.
Preferably, the particulate binder material is an epoxy, or a polyurethane, or a co-polyamide particulate resin.
C) The Abrasive Particles
The abrasive particles 14 can be of any type known to be suitable for use in domestic scouring articles, taking into account the nature of the surfaces to be cleaned and the scouring action desired. Included among the suitable abrasive materials are particles of inorganic materials, for example aluminum oxide including ceramic aluminum oxide, heat-treated aluminum oxide and white-fused aluminum oxide; as well as silicon carbide, tungsten carbide, alumina zirconia, diamond, ceria, cubic boron nitride, silicon nitride, garnet, and combinations of the foregoing. It is contemplated that abrasive agglomerates may also be used in the invention such as those described in U.S. Pat. Nos. 4,652,275 and 4,799,939. Suitable abrasive particles also include softer, less aggressive materials such as thermosetting or thermoplastic polymer particles as well as crushed natural products such as crushed nut shells, for example. Suitable polymeric materials for the abrasive particles include polyamide, polyester, poly(vinyl chloride), poly(methacrylic) acid, polymethylmethacrylate, polycarbonate, polystyrene and melamine-formaldehyde condensates. The abrasive particles 14, like the particulate binder material 15, should be of a size suitable for use in the electrostatic spray gun 17.
For a wiping article that has a non-scratch scouring action, preferred abrasive particles are polyamide or PVC.
Methods of producing wiping articles in accordance with the invention are described in greater detail in the following non-limiting examples. All parts and percentages quoted are by weight unless otherwise indicated.
The examples used the following materials, equipment, and test methods.
Materials
Semi-disposable microfibre web material: a material of the type used for wipes available under the trade name “Scotch-Brite™ Dusting Cloth” from 3M Company of St. Paul, Minn., U.S.A.
Epoxy resin powder: “Beckrypox AF” low temperature cure blue thermoset powder (mean particle size 35 microns) from DuPont of Montbrison, France.
Equipment
Test Methods
The PET-rayon wipe material was conveyed continuously through the powder coating booth. The stencil was placed on the length of web material immediately up-stream of the coating booth and the plate underneath. As that length of web material was moved through the coating booth, a mixture of 75% epoxy resin powder and 25% polyamide particles was directed at the stencil by the “Versaspray II” spray gun located 30 cm above the mesh conveyor. The powder mixture was supplied to the spray gun from the hopper in which it was fluidized until gentle bubbling using air at a pressure of 0.5 bar. The air pressure settings of the spray gun were 2-3 bar for the flow (or primary air) and 1-1.5 bar for the atomizing (or secondary) air and the maximum voltage (100 kV) was applied. The powder was deposited on the stencil at a weight of about 50 g/m2. The stencil-covered part of the web was then moved out of the coating booth, and the stencil and plate were removed leaving a pattern of powder deposits on that part of the web material, which was then moved into the gas oven and heated at 170° C. for 2 min to fuse and cure the epoxy resin in the deposits and form a pattern of abrasive areas on the surface of the web material. A low speed setting was used for the recirculating air in the gas oven, to avoid dislodging the resin powder. In the meantime, the stencil was cleaned using an air blower to remove the powder mixture that had been deposited on it in the coating booth: the reclaimed powder mixture was returned to the hopper of the coating booth, and the stencil and plate were re-used on another length of the web material.
Example 1 was repeated using powder mixtures in which the ratio of epoxy resin powder to polyamide particles was, respectively, 50/50; 95/5 and 100/0 (i.e., in Example 4, no polyamide particles were present in the powder mixture).
Example 1 was repeated except that the amount of powder deposited on the stencil in the 30 coating booth was, respectively, 100 g/m2 and 30 g/m2.
Example 1 was repeated except that the PET-rayon wipe material was replaced by, respectively, the PE/viscose/wood pulp material, the semi-disposable microfibre material; and the re-usable microfibre material.
Example 1 was repeated except that the epoxy resin powder was replaced, respectively, by the HD polyethylene powder; the copolyamide powder; the copolyester powder; the polyurethane powder; and the LD polyethylene powder. Flow aid powder was included with the thermoplastic powders in an amount of 0.5% by weight.
Results
The cut test was carried out using samples of wiping articles resulting from Examples 1 to 13. In addition, samples resulting from Example 8 were subjected five times to a domestic washing machine cycle at 95° C. and weighed following each cycle.
The scouring action of all of the samples tested could be classified as non-scratch, because the abrasive particles employed were comparatively soft and, according to a visual inspection, did not scratch a polycarbonate workpiece.
The cut test showed that all of the samples exhibited an adequate scouring performance for consumer use as a scouring wipe in domestic, industrial, hospital and food industry environments. The samples from Examples 11 to 13, in which softer resins were used, exhibited a gentler scouring action. Wiping articles exhibiting a gentler scouring action might find use as toiletry articles for cleaning human skin.
Samples from Example 4 indicated that an adequate scouring performance could be obtained through the use of a comparatively resin powder (possibly already formulated to include a filler material) without the use of additional abrasive particles.
Samples from Example 8 were found to be washable for at least 5 cycles at a temperature of 95° C.
Visual inspection of the samples from all of the Examples showed that the abrasive pattern on all samples was clear and well-defined.
An advantage of the process described in Example 1 above is that no volatile organic compounds (VOCs) are produced in the formation of the abrasive areas on the surface of the web material. In addition, the energy required in the process may be less than that required if a liquid, rather than a powder, resin were used. Consequently, the environmental effects of the process can be substantially less than those previously proposed for producing wiping article with a scouring action. In addition, due to the absence of liquids, the process is comparatively clean and the materials required are easy to handle. The examples also demonstrated that visually-attractive wiping articles with well-defined abrasive patterns could be produced in a comparatively simple manner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0311803.1 | May 2003 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US04/10844 | 4/8/2004 | WO | 11/21/2005 |
