Description

Non-woven cloth able to simultaneously absorb dirt particles and fugitive colourings of various chemical nature during household washing cycles in a washing machine.

The present invention relates to a non-woven cloth designed to be used during household washing cycles in a washing machine. The said cloth is composed of a non-woven fabric support that contains a polymeric matrix comprising chemical functionalities that ensure a) the capability of absorbing the particles of fugitive colourings that are poorly bound on the fabric and freed during the washing cycle of dyed garments in a washing machine and that may stain the other garments contained in the washing machine, preventing re-deposition on fabrics. This action is carried out on all families of colourings that may be released by the garments during washing cycles: direct and reactive colourings used to dye cotton, dispersed colourings for polyester, acid colourings for nylon and silk, premetallized colourings for wool and b) the capability to absorb, during the washing cycle in the washing machine, also the dirt particles contained in the washing water, preventing re-deposition on the garments that are being washed. The above is obtained by using a special aqueous dispersion of clay particles, since clay is known for its absorbing properties, in particular oils and greases. Supports used in household washing cycles in a washing machine are known on the market, generally consisting in non-woven cellulose- based fabrics, and also synthetic ones, containing molecules with specific functionalities, such as bleaching agents, detergents, oxidising agents, colour binders, decalcifying agents, optical whiteners or conditioners. The molecules with the aforementioned functionalities are adhered onto the surface of the material by means of physical impregnation and chemical anchoring processes. Once they are

introduced in the aqueous solution used for washing in the washing machine, the functional molecules that are more or less firmly anchored to the material of the non-woven cloth are released to carry out their action in solution or remain anchored to the support. In particular, cationic polymers are used as binders of fugitive colours (USP 3694364, USP 4065257, USP 4380353) since most colourings have anionic charge. The said molecules are not selective and can interact with other anionic molecules contained in higher concentration in the washing solution, such as the ones of many detergents, with optical whiteners. Most of all, not being perfectly anchored to the support fabric, if solubilized, they can contribute to fix the fugitive colour molecules on the garments that are being washed, given the high affinity of cationic agents for fabrics, especially cotton.

Moreover, the action of cationic polymers on fugitive colour particles with different chemical origin is not equally effective. In fact, the capacity to bind colours is very different according to the specific family of fugitive colourings. For instance, in the case of acrylic fibres dyed with basic colourings with positive charge, very poor affinity is obtained among fugitive colouring molecules and cationic agents due to the creation of electrostatic repulsion phenomena.

The present invention discloses the preparation of a non-woven cloth, preferably viscose or lyocell in view of higher mechanical strength than cotton, which comprises a synthetic matrix composed of an acrylic copolymer and specific chemical functionalities that give the cloth the capacity to simultaneously absorb dirt particles and fugitive colouring molecules contained in an ordinary household washing cycle in a washing machine, preventing re-deposition on other garments or articles subjected to the same washing cycle. In particular, the action of the aforementioned non-woven cloth is relevant on fugitive colourings from all families of colourings: reactive and direct colourings for cotton, dispersed colourings for polyester, acid colourings for nylon and premetallized acid colourings for wool. This is

due to the chemical nature of the chemical functionality anchored on the non-woven fabric cloth in order to inhibit colour fugitive molecules with polyvinylpyrrolidone-covinylmidazole copolymer base. Although these functionalities are present in the formulations of many detergents (DE 2814287, EP 372291 , EP 327927, DE4027832), they have no cationic charge, and therefore do not interact preferentially with anionic colourings only, favouring the creation of an aromatic-aromatic interaction with the aromatic component contained in almost all colouring molecules, regardless of the family they belong to. The absence of positive charge also minimises the risk of possible re- deposition on other fabrics of the eventually solubilized polymeric particles that do not show affinity for fabrics, unlike cationic polymers. The action of the non-woven cloth on the dirt particles is carried out because of the anchoring of clay particles, since clay is a material with high absorbing capacity with high affinity for lipidic molecules. Being a sedimentable material, clay must be maintained dispersed in solution to obtain uniform deposition on the non-woven cloth. This is obtained by using an aqueous dispersion that contains viscosizing and surfactant principles based on C-1 1 -14 iso C13-rich alcohols and ethoxylated tridecyl alcohol, able to prevent sedimentation of clay particles. The clayey particles deposited on the substrate do not have a specific chemical bind with the non-woven fabric and carry out their action in two ways: by being partially trapped in the non-woven cloth and by being released by the cloth to carry out their absorbing action of dirt particles in the washing solution and no longer in the surface of the non-woven cloth. Since the complex formed between the clay particles and the dirt particles in the washing solution has no affinity for fabrics, there is no risk of re-deposition of the dirt particles on the garments or other items that are being washed. The idea of the present invention provides for the realisation of a non- woven cloth according to a known process through the deposition and cohesion of a veil of discontinuous fibres with a chemical process,

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preferably made of viscose or lyocell in view of higher mechanical strength than cotton, and through the formation of a foam starting from a solution that contains the following as dry substance:

- from 10 to 80 parts of an acrylic polymer, preferably 55%, - from 1 to 10 parts of an anionic or cationic surfactant, preferably 2%

- from 1 to 50 parts of a solution of a copolymer mixture with polyvinylpyrrolidone-covynilimidazole base, preferably 20%,

- from 1 to 50 parts of a solution containing an anchoring polymer of epichlorhydhn derivation, preferably 10%, containing specific functionalities to bind the polymer both to the substrate cellulose and the polyvinylpyrrolidone-vinylimidazole-based copolymer.

- from 1 to 30 parts, preferably 10%, of an aqueous dispersion of clay particles containing ethoxylated alcohols.

- from 1 to 5 % of wetting agent, preferably 3%, based on tridecyl alcohol with low ethoxylation grade, containing from 1 to 10 moles of ethylene oxide, preferably 6 moles, in order to improve the wetting of the non-woven cloth to accelerate the fixation process of fugitive colouring molecules and dirt on the cloth during the washing cycles in a washing machine. The foam is homogeneous and uniformly deposited with a suitable apparatus on the entire surface of the non-woven fabric during the transportation of the fibre veil, is compressed through hydro-extracting rolls that compact the material and force the foam to penetrate into the pores of the non-woven fabric. After hydro-extraction, the material is conveyed into a suitable oven that contains the aforementioned foam, is treated at a temperature from 120 and 180°C, preferably 160°C, for a time from 45 and 90 seconds, preferably 60 seconds, in order to obtain final compaction through reticulation of acrylic polymer and anchoring reaction of molecules on the non-woven fabric.

The non-woven cloth has a weight ranging from 60 to 90 g/m ² , preferably from 70 to 80 g/m ² .

It is also possible to operate according to a second process, basically known as foulardage.

In this case the non-woven fabric with cellulose base that contains only the acrylic polymer and the surfactant is initially prepared with the aforementioned methodology. During a second operative phase the rolls of material are subjected to impregnation, according to which the fabric pulled on rolls passes through a metal container to absorb an aqueous solution composed of:

- from 5 to 20 parts of a polyvinylpyrrolidone-covinylimidazoly-based copolymer mixture, preferably 5 %, able to interact with the aromatic component contained in almost all families of colourings and especially azoderivates.

- from 1 to 10 parts of an anchoring polymer of epichlorhydrin derivation, preferably 3%, containing specific functionalities to bind the anchoring molecule both to the substrate cellulose and to the polyvinylpyrrolidone-vinylmidazole-based copolymer.

- from 5 to 10 parts, preferably 2 %, of an aqueous dispersion of clay particles able to absorb the dirt particles with fat matrix.

- from 0.1 to 1 % of wetting agent, preferably 0.2 %, based on thdecyl alcohol with low ethoxylation grade, containing from 1 to 10 moles of ethylene oxide, preferably 6 moles, in order to improve the wetting of the non-woven cloth and accelerate the fixation process of the fugitive colourings molecules and dirt on the cloth during the washing cycles in a washing machine. After passing through the metal container, the fabric impregnated with solution is subjected to hydro-extraction in continuous controlled mode to obtain absorption in weight of solution with respect to the weight of non-woven fabric that varies from 50 to 150%, preferably 100%. Then the fabric is subjected continuously to a combined treatment of mechanical and thermal stabilisation with rameuse, at temperatures from 100 to 160°C, preferably 130°C, for a time from 10 and 30 minutes, preferably 20 minutes. In this way the anchoring reaction of

the functional molecules on the non-woven fabric substrate is completed by the action of heat.

The non-woven cloth has a weight ranging from 60 to 90 g/m ² , preferably from 70 to 80 g/m ² . The wet mechanical strength of the non-woven cloth is an important parameter to determine its suitability for use in washing machines. The non-woven cloth must remain coherent, without flaking off during the washing cycle, a risk that may occur in case of non-woven fabrics in prolonged contact with aqueous solutions if their wet strength is low. With both aforementioned processes, the non-woven cloth illustrated in the present invention has tensile strength values both in longitudinal and transversal direction not lower than 1.5 Kgf, preferably not lower than 1.7 Kgf in longitudinal direction and 2 Kgf in transversal direction when measured with an axial dynamometer.