EP2126208A2

EP2126208A2 - Flexible, flat substrates having an abrasive surface

Info

Publication number: EP2126208A2
Application number: EP08708054A
Authority: EP
Inventors: Maxim Peretolchin; Günter Scherr; Roland Ettl; Volker Schädler
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-01-24
Filing date: 2008-01-22
Publication date: 2009-12-02
Also published as: BRPI0806567A2; RU2436881C2; US9623540B2; CA2674658A1; JP5371777B2; MX2009007097A; CA2674658C; WO2008090136A3; US20100095468A1; CN101589198A; WO2008090136A2; RU2009131659A; KR20090113282A; CN101589198B; JP2010516506A

Abstract

The invention relates to flexible, flat substrates having an abrasive surface, characterised in that they can be obtained by applying an aqueous solution or dispersion of at least one pre-condensate of a thermocurable resin on the upper and/or lower side of a flexible, flat substrate, in an amount of at least 5 to 90% in weight in relation to the non-coated, dry substrate, the pre-condensate is cross-linked and the treated substrate is dried.

Description

Flexible, flat substrates with an abrasive surface

description

The invention relates to flexible, flat substrates with an abrasive surface and their use as wiping cloths for cleaning household and industrial surfaces.

From WO 01/94436 a process for the production of elastic foams based on a melamine / formaldehyde condensation product is known. In this method, an aqueous solution or dispersion containing a melamine / formaldehyde precondensate, an emulsifier, a blowing agent, a curing agent and optionally conventional additives, foamed by heating to 120 to 300 ⁰ C and cross-linking the precondensate. The molar ratio of melamine to formaldehyde is greater than 1: 2. B. between 1: 1, 0 and 1: 1, 9. The available open-cell, flexible foams are mainly used for the thermal and acoustic insulation of buildings and parts of buildings, for the thermal and acoustic insulation of the interiors of vehicles and aircraft as well as for the low-temperature insulation z. B. in cold storage used. The foams are also used as insulating and shock-absorbing packaging material as well as due to the high hardness of cross-linked melamine resins for slightly abrasive cleaning, grinding and polishing sponges.

US Pat. No. 6,713,156 describes flat substrates whose surface exhibits a grinding action when rubbed on other objects. Such abrasive substrates are obtained, for example, by spraying, foaming or printing polymers on a flat surface such as nonwovens or paper by applying and curing the polymers unevenly thereon. The curing of the polymers must be done quickly because an uneven application of the polymer is responsible for the grinding action of the substrate. Have mensetzungen the Polymerzusam- used a minimum film forming temperature (MFT) of more than - 10 ⁰ C and containing at least one polymer having a Tg of at least 0 ⁰ C, usually from 20 to 105 ⁰ C. The polymer composition may comprise up to 20 weight % of additives contain z. Plasticizers, crosslinkers, starch, polyvinyl alcohol, formaldehyde thermosetting agents such as melamine, urea and phenol. The order quantity is generally more than 20% by weight, preferably from 30 to 50% by weight, based on nonwovens and other porous substrates. The nonuniformly coated with polymers substrates are used for example as a scouring cloths and wipes in household and industry, as cosmetic wipes and as swabs for wound treatment.

From US 2005/0202232 products are known which consist of at least one sheet-shaped melamine foam layer and at least one reinforcing layer. When Melamine foam is called Basotect ^® from BASF Aktiengesellschaft. Basotect ^® is an open-cell foam based on a melamine / formaldehyde condensation product. The sheet-shaped melamine foam layer and the likewise sheet-like reinforcing layer of cellulose fibers or natural or synthetic textile fibers see, for example, connected to each other by means of a hot melt adhesive. However, they may also be directly combined with each other depending on the kind of the reinforcing layer, for example, by the action of heat and optionally pressure. The products thus obtained, which have a melamine foam layer on at least one side of the sheet, are used as articles for cleaning and care of surfaces in the household and in industry because of the high hardness of the melamine foam layer. Preferably, these are disposables, which are disposed of after use. In most cases, they are wipes having a thickness of less than 5 mm, preferably 0.85 to 2 mm.

Glues and resins which are respectively sold as an aqueous binder or powders based on condensates of urea, melamine and formaldehyde as Kauramin ^® and Kaurit ^® from BASF Aktiengesellschaft, 67056 Ludwigshafen, is used in the furniture and building industry for the production of plate-shaped wood-based materials such as chipboard, plywood and shuttering panels, cf. Technical Information Kaurit ^® . Impregnated impregnated papers have a hard surface. Such products are found, for example, in surfaces of laminate flooring or in the decoration of furniture, cf. Technical Information Kauramin ^® .

To increase the wet strength of paper, you set z. As melamine / formaldehyde resins in the production of paper to the pulp before sheet formation, z. B.

Urecoll ^® K, BASF Aktiengesellschaft, 67056 Ludwigshafen. The amounts of resin present in the pulp, for example, about 0.5 to 1 wt .-%, based on dry pulp.

Known wipes such as kitchen roll or tissue, which are intended for single use, have no sufficient stability, in particular when wet, to ensure a sufficient wiping action.

From the earlier EP Application 06 1 16 165 a process for finishing paper and paper products with at least one finishing agent is known, wherein at least one finishing agent in the form of a pattern is applied to the top and / or bottom of paper or paper products. This process requires lower levels of finishing agents compared to known finishing processes to produce papers with comparable properties. Suitable finishing agents include, inter alia, melamine / formaldehyde resins and urea / formaldehyde resins into consideration. The invention has for its object to provide substrates with an abrasive surface for the cleaning of surfaces in the home and in the industry.

The object is achieved according to the invention with flexible, flat substrates having an abrasive surface, which are obtainable by applying an aqueous solution or dispersion of at least one precondensate of a thermosetting resin to the top and / or bottom of a flexible, flat substrate in an amount of at least 5 to 90 wt .-%, based on the uncoated, dry substrate, crosslinking of the precondensate and drying of the treated substrate.

By abrasive surface is to be understood that when moving this surface on another surface a rubbing or scouring action is exerted on the other surface. For example, while papers of tissue have practically no abrasive effect when used, the substrates of the present invention when wiping surfaces of glass, metal or plastic unfold a scouring effect desired for the cleaning of these surfaces. However, the abrasive effect is much less than emery paper, so that the substrates according to the invention are suitable for all those applications in which only a small abrasive effect is desired for the removal of dirt, so that the surface of the wiped with the substrates according to the invention Materials practically not damaged. The products according to the invention are preferably used as disposable items, but may also be used several times, depending on the particular application.

Examples of flat substrates are paper, cardboard, cardboard, woven, knitted and nonwoven fabrics. Paper, paperboard and paperboard can be made from all types of cellulosic fibers, both natural cellulosic fibers and recovered fibers, particularly recovered paper fibers, which are often used in admixture with virgin fibers. The fibers are suspended in water to a pulp which is dewatered on a wire to form a sheet. As a pulp for the production of pulps all common qualities in the paper industry come into consideration, for. B. wood pulp, bleached and unbleached pulp and pulps from all annual plants. Wood pulp includes, for example, groundwood, thermo-mechanical pulp (TMP), chemo-thermo-mechanical pulp (CTMP), pressure groundwood, semi-pulp, high-yield pulp and refiner mechanical pulp (RMP). As pulp, for example, sulphate, sulphite and soda pulps come into consideration. Preferably, unbleached pulp, also referred to as unbleached kraft pulp, is used. Suitable annual plants for the production of paper stocks are, for example, rice, wheat, sugar cane and kenaf. The weight per unit area of the paper products which constitute the planar substrate for the products according to the invention is, for example, 7.5 to 500 g / m ² , preferably 10 to 150 g / m ² , in particular 10 up to 100 g / m ² . Particularly preferred flat substrates are papers made of tissue and papers which have a structured surface, for example the household kitchen roll. Such paper products have, for example, a basis weight of 10 to 60 g / m ² . The flat substrates used may consist of one layer or be composed of several layers, for example, by superimposing and pressing the still moist layers immediately after production, or by gluing the already dry layers together with the aid of appropriate adhesives.

Woven fabrics, knitted fabrics and nonwovens, which are also suitable as flat substrates, usually consist of textile fibers or mixtures of textile fibers. Examples include fibers of cotton, cellulose, hemp, wool, polyamide such as nylon, Perlon ^® or polycaprolactam, polyester and polyacrylonitrile.

The thickness of the flat substrates is for example 0.01 to 100 mm, preferably 0.05 to 10 mm. It is usually in the range of 0.05 to 3 mm. The flat substrates are in the form of a web or a sheet, for example. Such materials are flexible. They retain their flexibility even after the application and curing of a thermosetting resin, which is to be applied at most in such an amount that the flexibility of the untreated substrate is just barely maintained. Although the flexibility of the untreated substrate decreases due to the application of the thermosetting resin, but the amount of resin is such that no rigid, inflexible structures arise, as they are common, for example, in furniture veneers. The paper coated according to the invention must by no means be brittle and should not break like glass during bending and folding. Cardboard coated in accordance with the invention can also be bent non-destructively, but has a substantially improved wiping effect compared with a non-coated cardboard.

To produce the flexible, flat substrates with an abrasive surface, flat substrates such as nonwovens, woven fabrics, knitted fabrics, paper, cardboard and paperboard are first treated with an aqueous solution or dispersion of a precondensate of at least one thermosetting resin. The precondensates of the thermosetting resins are selected from the group of melamine / formaldehyde precondensates, urea / formaldehyde precondensates, urea / glyoxal precondensates and phenol / formaldehyde precondensates.

Preferably, a precondensate of melamine and formaldehyde is used in which the molar ratio of melamine to formaldehyde is greater than 1: 2. The thermosetting resin used is preferably a precondensate of melamine and formaldehyde, in which the molar ratio of melamine to formaldehyde is 1: 1, 0 to 1: 1, 9. Melamine / formaldehyde condensation products can be up to Contains 50 wt .-%, preferably up to 20 wt .-% of other thermoset plasticizers and in addition to formaldehyde up to 50 wt .-%, usually up to 20 wt .-% other aldehydes condensed. Suitable thermoset formers are, for example, alkyl- and aryl-substituted melamine, urea, urethanes, carboxamides, dicyandiamide, guanidine, sulfurylamide, sulfonamides, aliphatic amines, glycols, phenol and phenol derivatives. As aldehydes, acetaldehyde, propionaldehyde, isobutyraldehyde, n-buturaldehyde, trimethylolacetaldehyde, acrolein, benzaldehyde, furfurol, glyoxal, glutaraldehyde, phthalaldehyde and terephthalaldehyde can be used, for example, to partially replace the formaldehyde in the condensates.

The precondensates may optionally be etherified with at least one alcohol. Examples of these are monohydric C 1 - to C 6 -alcohols, such as methanol, ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, isobutanol, n-pentanol, cyclopentanole, n-hexanol, cyclohehanol, n- Octanol, decanol, palmityl alcohol and stearyl alcohol, polyhydric alcohols such as glycol, diethylene glycol, glycerol, butanediol-1, 4, hexanediol-1, 6, polyethylene glycols having 3 to 20 ethylene oxide units, one-sided end-capped glycols and polyalkylene glycols, propylene glycol-1, 2, propylene glycol-1, 3, polypropylene glycols, pentaerythritol and trimethylolpropane.

The preparation of thermosetting resins belongs to the prior art, cf. Ullmann's Encyclopedia of Industrial Chemistry, Sixth Completely Revised Edition, Wiley-VCH Verlag GmbH Co. KGaA, Weinheim, "Amino Resins", Vol. 2, pp. 537-565 (2003).

It is based on an aqueous solution or dispersion of a precondensate, preferably from melamine and formaldehyde. The solid concentration is, for example, 5 to 95% by weight, preferably in the range of 10 to 70% by weight. The solution or dispersion of the precondensate usually contains at least one hardener. In special cases, you can also apply the usual for the condensation hardener separately on the sheet substrate. The hardener used is usually acidic compounds which catalyze the further condensation of the thermosetting resins. These amounts are for example 0.01 to 70 wt .-%, preferably 0.05 to 60 wt .-%, based on the resin. Suitable hardeners are, for example, inorganic and organic acids, for. For example, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, formic acid, acetic acid, oxalic acid, p-toluenesulfonic acid, sulfamic acid and acid anhydrides such as maleic anhydride or itaconic anhydride or salts of acids with ammonia or amines and sodium hydrogen sulfate and magnesium chloride.

The aqueous solution or dispersion of a precondensate of a thermosetting resin may optionally contain a surfactant. Suitable examples are nonionic, anionic and cationic surfactants and mixtures of at least one nonionic and at least one anionic surfactant, mixtures of at least one nonionic and at least one cationic surfactant, mixtures of several nonionic or of several cationic or of several anionic surfactants.

Suitable surfactants are, for example, all surfactants.

Examples of suitable nonionic surfactants are ethoxylated mono-, di- and tri-alkylphenols (degree of ethoxylation: 3 to 50, alkyl radical: C3-C12) and also ethoxylated fatty alcohols (degree of ethoxylation: 3 to 80, alkyl radical: C8-C36). Examples include the brands Lutensol ^® from BASF AG or the Triton ^® brands from Union Carbide. Particularly preferred are ethoxylated linear fatty alcohols of the general formula

n-CχH ₂ x ₊ iO (CH ₂ CH ₂ O) y H,

where x are integers in the range of 10 to 24, preferably in the range of 12 to 20. The variable y preferably stands for integers in the range from 5 to 50, more preferably 8 to 40. Ethoxylated linear fatty alcohols are usually present as a mixture of different ethoxylated fatty alcohols with different degrees of ethoxylation. The variable y in the context of the present invention stands for the mean value (number average). Suitable nonionic surface-active substances are also copolymers, in particular block copolymers of ethylene oxide and at least one C3-Cio-alkylene oxide, for. B. triblock copolymers of the formula

RO (CH ₂ CH ₂ O) yi- (BO) y ₂ - (AO) _m - (BO) y 3 - (CH ₂ CH ₂ O) y 4 R '.

wherein m is 0 or 1, A is a radical derived from an aliphatic, cycloaliphatic or aromatic diol, e.g. for ethane-1, 2-diyl, propane-1, 3-diyl, butane-1, 4-diyl, cyclohexane-1, 4-diyl, cyclohexane-1, 2-diyl or bis (cylohexyl) methane-4 '4'-diyl, B and B' are independently propane-1, 2-diyl, butane-1, 2-diyl or Phenyl- nylethanyl independently of a number from 2 to 100 and Y2, Y3 independently of a number from 2 to 100, wherein the sum of y1 + y2 + y3 + y4 is preferably in the range of 20 to 400, which corresponds to a number average molecular weight in the range of 1000 to 20,000. Preferably, A is ethane-1, 2-diyl, propane-1, 3-diyl or butane-1, 4-diyl. B is preferably propane-1,2-diyl.

Also suitable as surface-active substances with fluorine-substituted polyalkylene glycols, which are commercially available under the trademark Zonyl ^® (DuPont).

Suitable surface-active substances besides the nonionic surfactants are anionic and cationic surfactants. They can be used alone or as a mixture. The prerequisite for this, however, is that they are compatible with one another, ie that they produce no precipitation with each other. This requirement applies, for example, to mixtures of one compound class and for mixtures from nonionic and anionic surfactants and mixtures of nonionic and cationic surfactants. Examples of suitable anionic surfactants are sodium lauryl sulfate, sodium dodecylsulfate, sodium hexadecylsulfate and sodium di-octylsulfosuccinate.

Examples of cationic surfactants are quaternary alkylammonium salts, alkylbenzylammonium salts, such as dimethyl-C 2 - to cis-alkylbenzylammonium chlorides, primary, secondary and tertiary fatty amine salts, quaternary amidoamine compounds, alkylpyridinium salts, alkylimidazolinium salts and alkyloxazolinium salts.

Particularly preferred are anionic surfactants, such as. B. with sulfuric acid esterified (optionally alkoxylated) alcohols, which are usually used in neutralized with alkali lye form. Further customary emulsifiers are, for example, sodium alkyl sulfonates, sodium alkyl sulfates, such as, for example, sodium. For example, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sulfosuccinic. Furthermore, as anionic emulsifiers and esters of phosphoric acid or phosphorous acid and aliphatic or aromatic carboxylic acids can be used. Common emulsifiers are well described in the literature, see, for example, M. Ash, I. Ash, Handbook of Industrial Surfactants, Third Edition, Synapse Information Resources Inc.

The aqueous solution or dispersion of at least one precondensate may contain the surfactants in an amount of up to 10% by weight. If it contains a surfactant, the amounts of surfactant preferably present in the solution or dispersion are from 0.01 to 5% by weight.

The aqueous solution or dispersion of the precondensate may optionally contain other conventional additives, for. As dyes, biocides, particulate inorganic compounds such as silica, alumina, silicon carbide, titanium dioxide, zinc oxide, calcium carbonate, marble and corundum. The average particle diameter of the inorganic compounds is, for example, 1 nm to 500 μm. The amount of these additives is, for example, 0 to 100, preferably 0 to 25 wt .-%, based on the solution or dispersion. The aqueous solution or dispersion of a precondensate may also contain at least one perfume or perfume. If such substances are used, the amounts are, for example, 0.1 to 5, usually 0.2 to 1 wt .-%, based on the solution or dispersion. The flexible, sheet-like substrates according to the invention are preferably free of materials which, when rubbed on another surface, have a scouring effect, such as, for example, silicon carbide or aluminum oxide.

The aqueous solution or dispersion of the precondensate may also be 0 to

Contain 20 wt .-% of at least one polymeric additive. Examples of these are homo- and copolymers of N-vinylpyrrolidone, acrylamide, methacrylamide, acrylic acid, Methacrylic acid and salts of acrylic acid and methacrylic acid, polyvinyl acetate, polyvinyl alcohols, polyethyleneimines, polystyrenesulfonate, polystyrenesulfonic acid, polystyrene, butadiene in copolymerized polymers such as copolymers of styrene and butadiene, copolymers of styrene, butadiene and acrylic acid, copolymers of styrene, acrylonitrile and butadiene, polyacrylonitrile , Copolymers of acrolein, homopolymers and copolymers of alkyl acrylates, homo- and copolymers of alkyl methacrylates, polyamides, polyesters and polyformaldehyde.

In order to produce the products according to the invention, the solution or dispersion of the precondensate (hereinafter also referred to as "preparation solution") can be applied either over the entire surface or in the form of a pattern to the substrate. The preparation solution can also be foamed before application to the sheet substrate, z. B. by stirring in air or other gases. One then obtains area substrates, which are coated with a foam whose cells in contrast to a known foam of a thermosetting resin based on melamine and formaldehyde as Basotect ^® have an average diameter in the nanometer range, e.g., after curing and drying. B. 1 to 1000 nm.

The preparation solution is preferably applied in the non-foamed state to the relevant under consideration. It may, for example, by spraying, knife coating, rolling, printing or by means of suitable other technical devices known to those skilled in such. As a size press, a film press, an air brush, an aggregate for curtain coating, are applied to the flat surface. Preferably, non-contact methods or methods with the lowest possible pressure on the sheet substrate are used to reduce the displacement of the resin into the substrate.

The job can be done on one side or on both sides, either simultaneously or one after the other. The amount of curable resin which is applied to the flat substrate with the aid of the preparation solution is, for example, 5 to 90% by weight, preferably 10 to 80% by weight, in particular 20 to 70% by weight, based on the basis weight of the uncoated, dry sheet substrate.

It is thus significantly above the amount that is normally used for wet-strength equipment of paper by adding a wet strength agent to a paper stock in the production of paper and substantially below the amount that is used for the production of decorative films by coating flat substrates with MeI - Amine / formaldehyde resins are used. The amount of precondensate applied to the substrate in each case has a decisive influence on the flexibility, softness and feel of the products according to the invention. In addition, the distribution of the preparation solution or of the cured resin on the substrate has a considerable influence on the flexibility of the products according to the invention. For example, the preparation solution can be applied unevenly to the substrate, covering, for example, the substrate over the entire area, but not uniformly distributed thereon. Another variation consists of printing the preparation solution on the flat substrate according to the pattern. Thus, for example, particularly flexible products are obtained by printing the preparation solution in the form of parallel strips or punctiform on the substrate.

After the preparation solution has been applied to the flat support, the crosslinking of the thermosetting resin and the drying of the sheet-like substrates provided with an overlay of a precondensate of a thermosetting resin are carried out, wherein crosslinking and drying can take place simultaneously or successively. An advantageous embodiment consists in crosslinking the thermosetting resin in a humid atmosphere and then drying the product. The thermal curing of the resins and the drying of the products can, for example, in the temperature range from 40 to 250 ⁰ C, preferably 50 to 200 ⁰ C, particularly preferably 80 to 140 ⁰ C. The drying step, for example, in gas dryers or in I RT made rocknern become. The higher the particular temperature applied, the shorter the residence time of the material to be dried in the drying device. If desired product of the invention may be annealed after drying even at temperatures up to 300 ⁰ C. Even temperatures above 300 ⁰ C can be used to cure the resin, but then the required residence times are very short.

This gives flexible, flat substrates, which are used as wipes for the cleaning of surfaces in the household and in the industry. They are particularly suitable as abrasive wiping cloths for the surface cleaning of objects made of metal, glass, porcelain, plastic and wood. The products of the invention are particularly useful as disposables, but may optionally be used several times. A repeated use is given above all in such products according to the invention, which contain as a base a woven or non-woven.

The percentages in the examples are by weight unless otherwise indicated in the context.

Examples

Preparation solution 1

From a powdered precondensate of melamine and formaldehyde (KMT Kauramin ^® 773 (powder, BASF)) water was added a 20% aqueous solution was prepared, by completely desalinated water presented in a beaker earned the powder slowly and the mixture is then treated 1 hour by an Ultra-Turrax ^®, which was set at the highest level. Thereafter, the aqueous solution of the precondensate was filtered through a fluted filter. To 30 g of this solution were added 3.5 g of formic acid (100%) and 100 .mu.l of a fluorine-substituted surfactant (Zonyl ^® FS 300, DuPont) and stored for 6 minutes at a temperature of 70 ⁰ C in a drying oven.

example 1

On a 23.8 cm x 25.7 cm piece of kitchen roll (TORK (premium) kitchen roll) with a basis weight of 53 g / m ² , a portion of the preparation solution 1 was applied on one side with the aid of a 0.2-gauge squeegee. The amount of resin that was applied was 37% based on dry kitchen roll. In order to avoid that the cloth broke, it was underlaid with a protective paper. The coated material was then placed on an aluminum plate and dried for 15 min at 60 ⁰ C and a relative humidity of 90% in a climatic chamber. Subsequently, the coated with the preparation solution 1 cloth was stored for 15 min at 70 ⁰ C in a drying oven. After that, the paper was dry and networked. It had a basis weight of 73 g / m ² .

Example 2

A 34.3 cm × 24.1 cm sample of a paper having a basis weight of 36 g / m ² (TORK (Universal) Wiper 320 laboratory roll) was coated on one side with Preparation Solution 1 by the method given in Example 1, dried and networked. The amount of resin applied to the substrate was 26%. The basis weight of the coated substrate was then 45 g / m ² .

Example 3

On a 34.3 cm x 24.1 cm sample of paper with a basis weight of 53 g / m ² (TORK (Universal) Wiper 320 laboratory roll) was sprayed one-side preparation solution 1. The amount of resin applied was 25% based on dry paper. The coated sample was dried and crosslinked as indicated in Example 1. The basis weight of this sample was 66 g / m ² .

Example 4

Preparation sample 1 was sprayed on both sides of a 34.3 cm by 24.1 cm sample of 53 g / m ² paper (TORK (Universal) Wiper 320 laboratory roll). The total amount of resin applied was 51% based on uncoated paper. The coated sample was dried and crosslinked as indicated in Example 1. The basis weight of the sample was then 80 g / m ² .

Example 5

A black paper with a basis weight of 80 g / m ² was coated according to the method described in Example 1, dried and crosslinked. The amount of resin applied to the paper was 35% based on uncoated dry paper. The surface of the paper was evenly coated with no visible streaks of resin. The coated, dried and crosslinked paper had a basis weight of 108 g / m ² .

Example 6

A paper measuring 22.0 cm x 16.3 cm (Legamaster blotter sheet) and a basis weight of 47 g / m ² was coated, dried and cured as described in Example 1. The amount of resin applied to the paper was 67% based on uncoated, dry paper. The basis weight of the thus treated sample was 79 g / m ² .

Example 7

A paper with the dimensions 22.0 cm x 16.3 cm (Legamaster blotter (table cloth)) and a basis weight of 47 g / m ² was as described in Example 4, sprayed on both sides with Preparation Solution 1, dried and crosslinked. The total amount of resin applied was 27% based on uncoated, dry paper. The basis weight of the thus treated sample was 60 g / m ² .

The coated papers obtained according to the Examples were tested for their suitability as wipes and compared to commercial, uncoated papers. For this purpose, the test sample was fixed in each case on one side of a cylindrical stamp with a diameter of 13 mm and a weight of 600 g with the aid of an adhesive. On a shaker for a plate having a surface of a melamine / formaldehyde resin (Formica ^®) was attached. The surface of the plate was then stained with a permanent marker (Permanent Marker Eding 3000). In this area of the cylindrical stamp is provided, wherein the side of the punch that was covered with the sample to be tested, resting in each case on the plate Formica ^®. The area of the plate to be cleaned was moistened with 0.5 ml of completely demineralized water. The shaker worked with 20 double strokes / min with a horizontal deflection of the plate of 5 cm. If after 40 strokes no cleaning of the plate had been achieved (removal of the markings on the plate), a new sample was glued to the cylindrical stamp and the test piece continue to do so. The tests carried out and the results obtained are shown in the following table.

table

The sheet of Resopal ^® was coated with "Alpina Weiss" and soiled with crayon. Thereafter, tests were carried out with the following cleaning wipes:

Claims

claims

1. Flexible, flat substrates with an abrasive surface, characterized in that they are obtainable by applying an aqueous solution or dispersion of at least one precondensate of a thermosetting resin on the top and / or bottom of a flexible, flat substrate in an amount of at least 5 to 90 wt .-%, based on the uncoated, dry substrate, crosslinking of the precondensate and drying of the treated substrate.

2. Flexible, sheet-like substrates according to claim 1, characterized in that the precondensates of the thermosetting resins are selected from the group of melamine / formaldehyde precondensates, urea / formaldehyde precondensates, urea / glyoxal precondensates and phenol / formaldehyde precondensates.

3. Flexible, sheet-like substrates according to claim 1 or 2, characterized in that is used as the thermosetting resin, a precondensate of melamine and formaldehyde, wherein the molar ratio of melamine to formaldehyde is greater than 1: 2.

4. Flexible, sheet-like substrates according to claim 3, characterized in that the heat-curable resin used is a precondensate in which the molar ratio of melamine to formaldehyde is 1: 1, 0 to 1: 1, 9.

5. Flexible, sheet-like substrates according to one of claims 1 to 4, characterized in that the substrates are selected from the group of nonwovens, woven, knitted fabric, paper, cardboard and cardboard.

6. Flexible, sheet-like substrates according to one of claims 1 to 5, characterized in that the substrate is paper or a non-woven of cellulose fibers.

7. Flexible, sheet-like substrates according to one of claims 1 to 6, characterized in that the solution or dispersion of the precondensate contains at least one curing agent.

8. Flexible, sheet-like substrates according to one of claims 1 to 7, characterized in that the solution or dispersion of the precondensate contains at least one surfactant.

9. Flexible, sheet-like substrates according to one of claims 1 to 8, characterized in that the solution or dispersion of the precondensate contains 0 to 20 wt .-% of at least one polymeric additive.

10. Flexible, sheet-like substrates according to one of claims 1 to 9, characterized in that the solution or dispersion of the precondensate is applied over the entire surface of the substrate.

1 1. Flexible, sheet-like substrates according to one of claims 1 to 9, character- ized in that the aqueous solution or dispersion of the precondensate is applied in the form of a pattern on the substrate.

12. Flexible, sheet-like substrates according to one of claims 1 to 1 1, characterized in that the treated with an aqueous solution of a precondensate substrate is cured at a temperature in the range of 50 to 250 ⁰ C and dried.

13. Flexible, sheet-like substrates according to one of claims 1 to 12, characterized in that the amount of the thermosetting resin, based on the uncoated, dry substrate, 5 to 90 wt .-% is.

14. Use of the flexible, sheet-like substrates according to claims 1 to 13 as wiping cloths for the cleaning of surfaces in the household and in industry.