The present invention relates to an extremely long-lasting mop for cleaning surfaces, preferably for the wet cleaning of floors. The invention further relates to a method for wet cleaning of surfaces and to a method for manufacturing the mop.

For the cleaning of surfaces, in particular for the wet cleaning of floors, numerous different types of mop systems are known, usually comprising a handle and a mop attached to one end of said handle by a suitable fitting. The mop comprises a mount, equipped with a fitting for the attachment of the handle, and a cleaning active textile material fixed to the mount. In particular in the field of professional cleaning, where large surface areas, often heavily soiled with residues of different origin, have to be cleaned, preferably so-called flat mop heads are used, comprising a planar mount provided with fastening elements to reversibly attach a flat mop. These flat mops usually comprise a cover sheet, equipped on its top surface with fastening elements for the attachment of the mount/holding device, and a cleaning active side (scrubbing part) on its bottom side.

Numerous different textile materials have been used for said scrubbing part, which may consist of strands, fringes, loops, strips, tufts, velour-like material, terry-like material, or the like, and may be made of cotton, rayon, synthetic (man-made) fibres, or blends thereof. Mops for the wet cleaning of surfaces have to meet vari- ous requirements: They should take up the cleaning liquid quickly, transport it to the floor without dripping, and release it gradually to the floor during the cleaning process, while simultaneously taking up the soiled cleaning liquid. Additionally, a mop should be able to take up a large amount of solid soil particles and release very little fluff. Moreover, it should glide easily over the floor to avoid fatiguing the user, but on the other hand should also allow the removal of stubborn soil without the need for extensive mechanical action. Furthermore, the mop should remain its optics, size, and further characteristics, e.g. water absorption properties, even after numerous washing cycles at elevated temperatures. Up to now, no mop simultaneously meeting all of these requirements is known in the state of the art. The properties and characteristics of a mop depend on the shape of the trimming as well as on the material used in said trimming. Rayon, for example, has a rather high water absorption capacity, but is unsuitable for frequent washing at elevated temperatures. Cotton is more stable in frequent washing, but nevertheless shows considerable shrinking and an extended loss of fibres after frequent washing. In addition, cotton is comparable slow in drying, and mildew may become a problem in continuous wet use. Conventional synthetic fibres, on the other hand, show a rather good wear resistance including form-stability and a reduced greying in comparison to natural fibres, but have poor absorption properties. As a result, blends of natural and synthetic fibres are nowadays commonly used in the trimming of the cleaning active side of mops. Nevertheless, even these blends do not fulfil all of the requirements mentioned above, but always are a compromise.

In addition, conventional fibres in non-micro-fibre textiles, are rather large, and thus incapable of effectively removing particles and microbes smaller than the fibre itself (US 6,258,455). In recent years micro-fibres, i.e. fibres having a linear mass density (fineness) of less than 1 dtex (corresponding to a fibre weight of less than 1 g per 10.000 m of fibre), are increasingly used in the trimmings of mops. Such trimmings, comprising a high content of micro-fibres, have very good cleaning properties. On the other hand friction considerably rises with a rising content of micro-fibres, and in flat mops a mixture of threads consisting of micro-fibres and additional thicker synthetic or natural fibres is commonly used in the trimming of the cleaning active side of mops (EP 1 405 591 , US 5,887,311 ), or additional gliding adjuvants, such as PA-gliding stripes, are incorporated into the trimming.

The trimming of the cleaning active side, i.e. the scrubbing part on the bottom sur- face on the mop, may be in the form of a velour-like or a terry-like textile material, or may be composed of strands, loops, fringes, strips, tufts, or the like. If the trimming exclusively consists of strands or fringes, having open yarn ends, a high cleaning performance is achieved, but the gliding behaviour is poor. In addition, in particular trimmings with open yarn ends have a high tendency to give off fluff cleaning and washing of the mop, resulting in a considerable loss of trimming ma- terial over time. If on the other hand the trimming exclusively consists of loops instead of fringes or strands, friction and fluffing are reduced, but also the cleaning performance drops (US 5,887,311 ).

For this reason, mops, comprising a combination of loops and fringes, as de- scribed for example in DE 32 26 947 A1 , are particularly useful in the field of professional cleaning. The cleaning active side of such mops has two zones with different trimmings. The centre part of the cleaning active side is formed of loops, while the rim encircling said centre part is formed of fringes with open yarn ends. While the loops in the centre part take up the dirty water including the soil dis- solved therein, the fringes take up and retain solid soil particles, even penetrating into corners and along skirting boards. Due to the combination of loops and fringes, this type of mop has an improved gliding behaviour and a reduced fluffing in comparison to a mop, wherein the trimming exclusively consists on fringes, while the cleaning performance is improved in comparison to a mop, wherein the cleaning active side exclusively is formed of loops. Nevertheless, fluffing still is observed to a certain extent even in these mops. Up to now no such loops-and- fringes mops have been put into practice, wherein the whole trimming exclusively consists of a fine-fibre or a micro-fibre. A certain amount of conventional, i.e. thicker, synthetic or natural fibres still has to be present in the trimming to avoid too high a friction fatiguing the user (EP 0 104 591 ). As a consequence, even mops head coverings comprising a mixture of conventional fibres and micro-fibres become worn after a certain number of washing cycles, including linting, pilling, shrinkage and loss of shape.

It was therefore an object of the present invention to provide a mop for cleaning surfaces, preferably for the wet cleaning of floors, having good soil removing characteristics, both for solid and dissolved soil, a high and constant uptake and release of water, enabling the cleaning of large surface areas, a reduced friction / improved gliding properties, while simultaneously exhibiting a good wear resistance with respect to linting, pilling, shrinkage and stability of shape, keeping its characteristics and optics even after more than 500 washing cycles at elevated temperatures, e. g. 60 ⁰ C.

It has now surprisingly been found that this can be achieved by using a high- twisted fine fibre yarn as a thread for the trimming of the mop. One object of the present invention therefore is a mop for cleaning surfaces, preferably for the wet cleaning of floors, comprising: a cover sheet 2, and one or more threads of a twisted yarn, comprising 5 to 15 fine fibre yarns per twisted yarn, fixed to the cover sheet 2 in such a way, that the threads form the cleaning active scrubbing part of the mop on the bottom side of the cover sheet 2, wherein the linear mass density of the fine fibres in the fine fibre yarn is in the range of 0.1 to 2.4 dtex, and the number of turns per unit length of twisted yarn is in the range of 100 to 160 T/m.

In the terms of the present invention the term "twisted yarn" clearly has to be distinguished from the term "yarn". According to the present invention, a yarn is a long continuous strand of interlocked fibres or filaments, either of natural origin or man-made. While filaments consist of very long, thin cylinders of extruded material, either as a single strand (monofilament) or as grouped multiple strands (multifilament). Staple fibres are fragments of much shorter length of a material, commonly 25 to 180 mm in length, which are aligned in a more or less parallel fashion and adhere to each other during spinning. In a preferred embodiment of the pre- sent invention, the length of the stable fibers in is in the range of 35 to 40 mm, and most preferably is 38 mm. According to the present invention a twisted yarn (ply) is a strand obtained by twisting two or more single yarns with each other. In terms of the present invention a thread is a long continuous strand of textile material used for the manufacturing of other textile materials by sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the like.

The linear mass density, characterising the mass per unit length of a yarn, a twisted yarn, a thread, or other 1 -dimensional objects, is commonly given in tex, representing a mass in gram per 1 ,000 meters; den, representing the mass in grams per 9,000 meter; or metric number (Nm), representing the length per kilo- gram. The metric number may be converted to tex by the following formula: [tex] = 1 ,000 / [Nm]. Also decitex (dtex) are commonly used, corresponding to 0.1 tex. In terms of the present invention, a fine fibre is a fibre having a linear mass density in the range of 0.1 to 2.4 dtex. In a preferred embodiment, the linear mass density of the fine fibres is in the range of 1.0 to 2.0 dtex, preferably of 1.15 to 1.6 dtex. In another preferred embodiment, the linear mass density of the fine fibres in the range of 0.1 to 1.0 dtex, the fine fibres being micro-fibres.

In the twisted yarn used for the trimming of mops known from the state of the art the number of turns per unit length of twisted yarn is about 90 turns per meter (T/m), regardless if the twisted yarn is made of natural, conventional synthetic or micro-fibres. In contrast, the number of turns per unit length of the twisted yarn according to the present invention is in the range of 100 to 160 T/m. It has surprisingly been found that by using such a highly twisted yarn comprising 5 to 15 fine fibre yarns per twisted yarn, unravelling of the twisted yarn during usage and washing, as well as linting and pilling are significantly reduced, even in fringes 1 having open yarn ends. The trimmings comprising this high-twisted yarn exhibit a high uptake of soil, including solid soil particles, and an excellent uptake and release of water / cleaning solution, even though high twisted yarns are commonly thought to have a poor liquid absorption capacity. Furthermore, the trimmings made of the threads according to the present invention are less prone to incrustation by residual soil, which usually resembles a problem in mops made of micro- fibres or fine fibres known from the state of the art.

In addition, the mop according to the present invention keeps its optics and cleaning characteristics, even after 500 washing cycles at 60 ⁰ C, and is suitable for tumble drying. Due to the use of a synthetic fine fibre, almost no greying is observed, even after long-term usage.

Using the high-twisted yarn according to the present invention it is possible to manufacture a mop wherein the trimming exclusively consists of fine fibres, which shows excellent gliding properties and reduced friction even in comparison to a conventional mop, consisting of a mixture of cotton and conventional, i.e. non-fine, polyester fibres, and to a velour-type mop made of micro-fibres equipped with special gliding stripes, as demonstrated in the examples below.

The material of the cover sheet (backing textile) 2 is not particularly limited. In principle, any wear-resistant material known from the state of the art may be used, including woven or knitted fabrics of natural or manmade material. If a woven fabric is used as a cover sheet 2, the cover panel may be edged with a binding/border 6 to prevent the cover panel from fraying. Preferably a polyester fabric is used as a cover sheet 2.

For attaching the mop to a mount, the cover sheet 2 preferably comprises one or more fastening elements 3 attached to its top surface. Such fastening elements 3 are usually placed near the transversal edges of the mop, but may also be placed along the longitudinal edges thereof. Any fastening elements known from the state of the art including insertion pockets, holding strips, clamping means, buckles, burr / Velcro means (touch fasteners), and the like may be used. In an alternative embodiment, the majority of the top surface of the cover sheet or even the whole top surface of the cover sheet 2 may be equipped with a Velcro backing.

It is possible to use a twisted yarn comprising fine fibre yarns according to the present invention in combination with conventional natural or man-made yarns. It is, however, preferred that the twisted yarn exclusively consists of fine fibre yarns according to the present invention.

The twisted yarn preferably comprises 6 to 12, more preferably 7 to 10 and most preferably 8 fine fibre yarns per twisted yarn. In a preferred embodiment, the number of turns per unit length in the twisted yarn is in the range of 115 to 145 T/m, preferably of 120 to 130 T/m. In a particular preferred embodiment the twisted yarn comprises 8 fine fibre yarns per twisted yarn, and the number of turns per unit length in the twisted yarn is 130 T/m. The linear mass density of the one single yarn in the twisted yarn preferably is in the range of Nm 5 to Nm 15, more preferably Nm 7 to Nm 13 and most preferably is Nm 10 (100 tex). In a particular preferred embodiment, a twisted yarn of Nm 10/8 is used, comprising 8 single fine fibre yarns per twisted yarn, wherein the Nn- ear mass density of a single yarn is Nm 10.

The number of turns per unit length in one single yarn preferably is in the range of 300 to 500 T/m, more preferably of 350 to 450 T/m, and most preferably is 385 T/m.

The tenacity of the twisted yarn preferably is in the range of 15 to 40 cN/tex, pref- erably of 20 to 30 cN/tex, and most preferably of 23 to 27 cN/tex. The tenacity (breaking load) of a thread or a yarn is calculated from the yarn count and the breaking strength, i.e. the force that leads to the rupture of the thread / yarn.

The fine fibre yarns used in the twisted yarn may consist of staple fibres of fine fibres or filaments of fine fibres, preferably of staple fibres.

The fine fibres preferably are fine fibres, selected from the group consisting of polyester fine fibres, polyamide fine fibres, polyacryl fine fibres, viscose fine fibres, polypropylene fine fibres, polyethylene fine fibres, or a mixture thereof. More preferably the fine fibres are polyester fine fibres.

The mop of the present invention may have any design known from the state of the art for the moist and/or wet cleaning of floors. In a preferred embodiment, the mop is a flat mop to be attached to a planar mount. In a further preferred embodiment, this flat mop has a rectangular shape, optionally with rounded edges.

The cleaning active scrubbing part may consist of strands, loops, fringes, strips, tufts, or the like, made of the thread of the present invention. In a preferred em- bodiment, the thread(s) is (are) fixed to the cover sheet 2 in such a way, that the cleaning active scrubbing part of the mop is composed of loops 5 and/or fringes 1 of the thread(s), preferably of a combination of loops 5 and fringes 1. In a further preferred embodiment, the centre part of the cleaning active scrubbing part is formed of loops 5 of the thread(s), whereas the rim is formed of fringes 1 of the thread(s). The length L of a single loop 5 preferably is in the range of 0.5 to 5 cm, more preferably of 1 to 4 cm, even more preferably of 2.2 to 2.8 cm, and most preferably is 2.4 cm. The length L of the fringes 1, 4 preferably is in the range of 1 to 10 cm, more preferably of 3 to 8.5 cm, even more preferably of 4.5 to 7 cm, and most preferably is 5 cm. In a particular preferred embodiment, the mop comprises loops 5 and two types of fringes 1 and 4 of different length L, wherein the centre part of the cleaning active scrubbing part is formed of loops 5, surrounded by an inner rim formed of fringes 4 of a defined length l_i, said inner rim being surrounded by an outer rim formed of fringes 1 of a defined length L ₂ , wherein the fringes of the outer rim 1 are longer than those of the inner rim 4 (L ₂ > Li ). The length L of the loops 5 and fringes 1/4 is measured from the cover sheet 2 to the end of the loop 5 or fringe 1/4 on the cleaning active scrubbing part.

Different ways of attaching one or more thread(s) to a knitted or a woven cover sheet 2 are known to a person skilled in the art. Preferably, the thread(s) is fixed to the cover sheet 2 by tufting. In addition, the trimming may be additionally fixed to the cover sheet 2 by a finishing process, such as a heat treatment, gluing, or the like.

In a preferred embodiment, more than 50%, preferably more 80%, more preferably more than 90%, and most preferably 100% of the thread(s) forming the cleaning active scrubbing part of the mop are twisted yarns according to the present invention.

The present invention also provides a method for the wet cleaning of surfaces, preferably for the wet cleaning of floors, using a mop according to the present invention. As demonstrated by means of the following examples, this method allows an ergonomic, user-friendly wet cleaning of surfaces ensuring a high cleaning efficiency. The invention further provides a method for manufacturing a mop according to the present invention, comprising the step of tufting through the cover sheet 2 one or more thread(s) of twisted yarn according to the present invention, comprising 5 to 15 fine fibre yarns per twisted yarn and having a number of turns per unit length of twisted yarn in the range of 100 to 160 T/m.

Description of the Drawings

Figure 1 is a view on the top surface of a preferred embodiment of the mop of the present invention, showing a cover sheet 2, edged with a binding 6, with attached fastening elements 3 and fringes 1 surrounding the rim of the cleaning active scrubbing part on the mop's bottom surface.

Figure 2 is a view on the bottom surface of mop, forming the cleaning active scrubbing part, with a centre part formed of loops 5, surrounded by an inner rim formed of fringes 4, said inner rim being surrounded by an outer rim formed of fringes 1 of a different length.

Figure 3 is a detail of the cover sheet 2 showing the thread tufted through the cover sheet to form loops 5. The length L of the loops 5 is measured from the cover sheet 2 to the end of the loop 5 on the cleaning active scrubbing part.

Examples

To evaluate the performance and wear resistance of the mops of the present invention, a mop covering according to the present invention was compared to two mops known from the state of the art. The first commercially available mop (com- parative example 1 , CE 1 ) consisted of a blend of 50% cotton and 50% conventional, i.e. non-fine, polyester fibres, comprising a centre part formed of loops and a rim formed of fringes.

The other commercially available mop (CE 2) had a velour-like trimming made of polyester micro-fibres equipped with polyamide(PA)-gliding stripes, necessary to reduce the friction of the wet mop on surfaces.

The trimming of the mop according to the present invention was composed of 100% polyester fine fibres according to the present invention, consisting of 8 fine fibre yarns per twisted yarn, wherein the linear mass density of a single fine fibre in the fine fibre yarn was in the range of 1.15 to 1.6 dtex, and the number of turns per unit length in the twisted yarn was 130 T/m. The centre part of the cleaning active scrubbing part of the mop according to the present invention was formed of loops 5, whereas the rim was formed of fringes 1/4. All mops had a dimension of about 40 cm x 12 - 15 cm, measured without passament.

Example 1 : Water absorption

A test method analogous to DIN 5392 was used. At the beginning, the dry weight of the mops (m _d ry) was determined on a laboratory scale. The mops were then immersed into a basin filled with deionised water for 180 +/- 3 seconds, in such a way, that the mop completely laid approximately 1 cm under the water surface, and no bubbles were present under the mop. The mops were then removed from the basin, and immediately hung up, clamping them at the narrow side. After let- ting drip the mops for 180 +/- 3 seconds, the wet weight of the mops (m _we t) was determined.

The absolute water absorption w _A was calculated according to the following formula: W _A = m _we t - nridry, giving the amount of absorbed water in gram per mop. The relative water absorption w _R was calculated by the following formula: w _R = (m _we t - nridry) / nridry, giving the amount of absorbed water in gram per gram of mop material. The results are presented in table 1.

Table 1 : Water absorption capacity

The mop according to the present invention keeps its excellent water absorption capacity almost constantly even after 500 washing cycles at 60 ⁰ C, exhibiting only 8% loss of performance with respect to absolute absorption capacity, while the other two commercially available mops show a loss of performance of 18% and 23% respectively. With respect to the relative absorption capacity, taking into ac- count the change of weight of the mop after 500 washing cycles, the mop according to the present invention shows no loss of performance, while the two coverings known from the state of the art show a loss of performance of 15% and 46 %.

Example 2: Water release

In order to evaluate the amount of cleaning solution released to the floor during the cleaning process and to determine the cleaning area output of the mop after one single saturation, the following experimental set up was used: At first, the dry weight m _d ry of each mop was determined on a laboratory scale. Each mop was then immersed in an aqueous cleaning solution (1 % Sopal ^® , Ecolab, Germany) for 2 to 3 seconds, and afterwards pressed in a vertical press with a force of 100 N for 10 seconds. The weight of the wet mop (m _we to) was then determined. The mop was attached to a mount, and the cleaning experiment was started. As a test floor, a covered PVC-floor, separated in sections of 4.39 m ² was used. Each section was cleaned by the so-called figure-of-8 wiping process, in which the mop is moved along the floor in such a way that its path is shaped like the number 8, i.e. two circles or ellipses having a point of contact. After cleaning the first section in that way, the weight of the wet mop (m _we ti) was determined. The second section of the test floor was then cleaned without re-wetting the mop, and the weight of the wet mop after cleaning the second section (m _we t2) was determined. This procedure was repeated, until water release was too poor to allow a well wetting of the floor, corresponding to a release of cleaning solution of less than 15 g per section. The Examples are presented in table 2.

Table 2: Water release after 5 washing cycles

¹ wetting too poor

The mop according to the present invention allows to clean a larger surface area per single wetting of the covering, and the average amount of water given off per m ² of surface is higher than in the two comparative examples. Example 3: Friction / Gliding Properties

To evaluate the gliding properties of the wet mops, each mop was immersed into an aqueous cleaning solution (1 % Sopal ^® ) for 2 to 3 seconds, and afterwards pressed in a vertical press for 10 seconds with a force of 100 N. The mop was fixed to the mop mount, and the tackle used for pushing the mop over the test floor was bent. As a test floor, an uncoated, untempered marbled linoleum floor from Armstrong DLW used. To measure the sliding, the mobile measuring unit GMG 100 for the measurement of sliding friction coefficient on floor surfaces from GTE lndustheelektronik (Viersen, Germany), equipped with a neutral slider plate and a Velcro fixation to fix the apparatus on the mop mount was used. The sliding GMG 100 was put in the centre of the mop mount, and the measurement was started recording the gliding coefficient on a test distance of 1.5 m. The measurement was repeated five times for each mop on different parts of the test floor without wetting the mop again. The gliding coefficient was determined by averaging the gliding coefficients of the last three scans. The higher the value obtained, the poorer are the gliding properties of the mop. The results are presented in table 3.

Table 3: Friction

The mop according to the present invention shows very low friction in comparison to the other two mops, even though its cleaning active scrubbing part completely consists of fine fibres, and does not comprise any gliding adjuvants, such as gliding stripes. Example 4: Loss of Material and Incrustation

To evaluate the extent of loss of trimming material or incrustation caused by frequent washing, the weight of a sample of each mop was determined on a laboratory scale before and after having been washed at 60 ⁰ C five hundred times. The results are presented in Table 4.

Table 4: Loss of Material and Incrustation

For the mop of the present invention, only 9% reduction of weight was observed even after 500 washing cycles at 60 ⁰ C, whereas the conventional cotton / polyes- ter mop showed 15% reduction of weight due to loss of fibres. The commercially available micro-fibre velour mop on the other hand increased its weight by more than 30% due to incrustation.

In summary, in the mop of the present invention only 9% reduction of weight was observed even after 500 washing cycles at 60 ⁰ C, whereas the conventional cotton / polyester mop showed 15% reduction of weight due to loss of fibres. The commercially available micro-fibre velour mop on the other hand increased its weight by more than 30% due to incrustation. The mop according to the present invention furthermore allows to clean a larger surface area per single wetting of the covering, and the average amount of water given off per m ² of surface is higher than in the two comparative examples. What is even more important, is the fact that the mop according to the present invention keeps its excellent water absorption ca- pacity almost constantly even after 500 washing cycles at 60 ⁰ C, exhibiting only 8% loss of performance with respect to absolute absorption capacity, while the other two commercially available mops show a loss of performance of 18% and 23% respectively. With respect to the relative absorption capacity, taking into account the change of weight of the mop after 500 washing cycles, the mop accord- ing to the present invention shows no loss of performance, while the two coverings known from the state of the art show a loss of performance of 15% and 46 %. Even more surprising is the fact that the mop according to the present invention shows very low friction in comparison to the other two mops, even though its cleaning active scrubbing part completely consists of fine fibres, and does not comprise any gliding adjuvants, such as gliding stripes.

[0048] It has been demonstrated that the mop according to the present invention is extremely long lasting, keeping its characteristics constantly even after 500 washing cycles at high temperatures, and allows a user-friendly, ergonomic cleaning due to its low friction.