MXPA00001814A - Porous material, method for making same and applications - Google Patents

Abstract

The invention concerns a porous material, a method for making same and its applications. Said porous material comprises a mixture of cellulose fibres and at least an elastomer and is characterised in that it has a honeycomb structure having cells with a size ranging between 0.1 and 10 mm, a density of the order of 0.03 to 0.1, water absorbing capacity not less than 750%, and water holding capacity after manual wringing less than 100%. The invention is applicable for making in particular sponges and household goods comprising aspongy element such as brushes and squeegees for cleaning surfaces.

Description

POROUS MATERIAL, ITS MANUFACTURING PROCESS AND ITS APPLICATIONS The present invention relates to a porous material, to a process for preparing it and to its applications, especially for the manufacture of sponges and household articles, which include a spongy element, such as sponge rags, squeeze mops and brush brushes. rubber to clean surfaces. In the field of household cleaning, the sponges that are used mainly are sponges derived from plants, which are based on regenerated cellulose, and synthetic sponges which usually consist of open cell polyurethane foams. Although sponges based on regenerated cellulose have, as a general rule, very satisfactory properties, both in terms of their water absorption and water containment capacities, squeezing capacity, flexibility, firmness, mechanical strength and water resistance, detergents and heat, its manufacture, however, causes great problems. This is because these sponges are manufactured by processes that consist first of converting the cellulose into a viscous pulp, whose conversion is carried out by treating the cellulose with sodium hydroxide, dissolving the alkaline cellulose that was formed in that way in carbon disulfide. and treating the resulting cellulose xanthan in sodium hydroxide. Subsequently, after incorporating l # reinforcing fibers (hemp, linen, cotton, etc.), inks and crystals of sodium sulfate in the viscous pulp that was obtained in this way and after forming by molding or extrusion, is heated the compound, which makes it possible for the viscose to solidify and the cellulose to be regenerated therefrom by evaporation of the carbon disulfide and causing the sodium sulfate crystals to melt, which, by means of removing them, leave in their place a multitude of cells. , In this way, the implementation of these processes on an industrial scale, given the natural nature [sic] so corrosive and toxic of the products used, requires very specific plants, which are very expensive both in terms of investment and operating costs, is highly polluting despite the decontamination equipment that these plants include and the measures that are take to limit the harmful effects on the environment, and has relatively low production yields. Polyurethane foam sponges are obtained through significantly less constrictive manufacturing processes, which are based on a reaction of condensation between a polyol and a polyisocyanate in an aqueous phase, but they do not have the disadvantage of being of a relatively hydrophobic nature, which results in humidification, water and moisture containment properties.

["Twists that are inadequate, regardless of the many treatments that have been proposed in the prior art to make more hydrophilic polyurethane foams. In addition, it has been proposed in US-A-4, 559, 243 the production of spongy structures in the form of sheets a few millimeters thick by means of depositing, on a support such as a woven, non-woven or plastic sheet, a foam made of a mixture of a latex and hydrophilic fibers, of the cellulose-comprising type, viscose or even polyvinyl alcohol fibers, and then subjecting the compound to heating operations to coagulate the foam and to stabilize it in an open cell structure by drying and crosslinking. Although the manufacture of these spongy structures, such as polyurethane foam sponges, is free of the disadvantages of the processes for V the manufacture of sponges derived from plants, is the However, these structures have a low absorbency, which considerably limits their importance. Consequently, the applicant was given the task of providing sponges that have all the qualities that are required for domestic use and, especially, the capacity to absorb a large volume of water and to retain the water that was absorbed in that way for as long as desired so as not to expel it actively, the capacity, however, to release this water under the effect of manual twisting and a capacity to clean raised, the manufacture of these sponges is simple to implement, does not require a large industrial investment, does not use corrosive substances or toxic substances, is propitious to the environment and is characterized by its economically advantageous levels of productivity. This objective is achieved, according to the present invention, by a porous material comprising a mixture of cellulose fibers of at least one elastomer, characterized in that it has: - a honeycomb structure that is formed by cells whose size is between 0.01 and 10 millimeters; - a relative density between 0.03 and 0.1; - a water absorption capacity of at least 750 percent; and - a water containment capacity, after manual twisting, of less than 100 percent. In the context of the present invention, it should be understood that the term "water absorption capacity" means the proportion, expressed as a percentage, of the mass of water that can be absorbed by the porous material when it is completely immersed in a volume of water with the dry mass of this porous material, and it should be understood that the expression "water holding capacity after manual twisting" means the proportion, also expressed [• as a percentage, of the mass of water retained in the porous material 5 after it has been manually squeezed with the dry mass of that porous material. The cellulose fibers useful in accordance with the invention are all natural cellulose fibers such as wood cellulose fibers or fibers for the manufacture of wood. paper (coniferous or deciduous wood fibers, bleached or unbleached), cotton, linen, hemp, jute or henequen fibers or instead, fibers regenerated from rags. These could also be long fibers (this means fibers of more than 1 centimeter in length), short fibers (which have a length of less than 3 millimeters) or fibers of intermediate length (between 3 millimeters and 1 centimeter in length) or else these could be composed of a mixture of fibers of different lengths. In this way, for example, excellent results have been obtained by using any long cellulose fibers, prepared by cutting sheets of cotton lint into filaments having a size of a few centimeters, either alone or in combination with short cellulose fibers such as those sold under the trademark of ARBOCELL by Rettenmaier & Sóhne and which measure approximately 900 μm in length, or medium length cellulose fibers, which were also prepared by cutting sheets of cotton lint, but in filaments having a length of between about 8 millimeters and 1 centimeter . In addition, regardless of their length, the cellulose fibers that can be used in the invention, could have been previously advantageously subjected to a suitable treatment to promote their kinking within the elastomer and, consequently, their adhesion to that elastomer . East The treatment may consist, for example, of a fibrillation treatment, this means mechanical agitation which has the effect of releasing the fibrils on the surface of the fibers, allowing them to be trapped with each other, or of an exposure to the fibers. ultraviolet radiation which, by means of cause reactive sites to form on the surface of the fibers, allows chemical fixation of these fibers. As an example of commercially available cellulose fibers that have experienced fibrillation, mention should be made of the fibers sold under the trademark LYOCELL by Courtaulds Chemicals. With respect to the elastomer useful according to the invention, it can be chosen from many elastomers as long as these elastomers are compatible with cellulose and therefore do not have a pronounced hydrophobicity. In this way, the elastomer will be advantageously selected from polybutadiene yarns, butadiene-styrene copolymers, butadiene-acrylonitrile copolymers (or nitrile rubbers), ethylene-propylene copolymers and fc terpolymers, styrene-block copolymers butadiene or styrene-isoprene, styrene-ethylene-butylene-styrene block copolymers, elastomers. thermoplastics derived from polyolefins (such as the SANTOPRENE * from AES or the ® VEGAPRENE from Hutchinson), octene-ethylene copolymers (such as those sold under the trademark ENGAGE), copolymers of ethyl acrylate and other acrylates, such as the terpolymers of acrylate-ethylene-acrylic acid (such as those sold by DuPont de Nemours and Exxon under the references VAMAC and ATX 325, respectively), or terpolymers ® of acrylate-acrylonitrile -styrene (such as the SUNIGUM of Goodyear), polychloroprenes, chlorinated polyethylenes, and mixtures thereof. Furthermore, with respect to the polyolefin elastomers mentioned above, and especially the rubbers of > polybutadiene, butadiene-styrene, and butadiene-acrylonitrile, It has been found that the use of carboxylated derivatives of these elastomers is particularly advantageous due to their ability to form, by ionic bridges between the carboxyl functional groups in the presence of divalent or trivalent metals, such as zinc, calcium or aluminum, a network that plays a part in providing the porous material with unsatisfactory cohesion. According to the invention, the porous material can include, in addition to the cellulose fibers, synthetic fibers suitable to act as a reinforcement within the elastomer and make it possible either to further increase the cohesion of the porous material and consequently its strength Mechanical when it is shown that this is necessary, or that the amount of elastomer necessary to obtain adequate cohesion is reduced and thus reduce the cost of manufacturing that material. As examples of suitable synthetic fibers, mention should be made of polyamide fibers, polyester fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers and polyvinyl alcohol fibers, it being understood that, whatever the chemical nature of the fibers that were chosen, it will be preferred to use fibers that have sufficient tenacity, so that they can fulfill their role as reinforcing fibers, and sufficient flexibility to prevent them from hardening the porous material that is finally obtained. In any situation, when these reinforcing fibers are present in the porous material, they conveniently represent at most 20 percent, and preferably between 5 and 15 percent by mass, of the total mass of the fibers present in this material. .

The porous material according to the invention may also conveniently comprise one or more polymers suitable for use as agents that act as an interconnection between the cellulose fibers (and, optionally, the synthetic fibers) and the elastomer, and of this way to promote their mutual adhesion. To do this, this or these polymers will preferably have a more hydrophilic nature than the elastomer. As examples of the polymers that can be used, mention may be made of polyvinyl alcohols (ELVANOL ", by DuPont de Nemours, GOHSENOL® by Nippon Goshei, etc.), melamine-formaldehyde resins (CYREZ 963 E.

Cytec, RESIMENE s 3521 from MONSANTO, etc.), vinyl adhesives or wood adhesives, or polyurethanes. When these polymers are present in the porous material, these could represent up to 35 parts per mass per 100 parts per mass of the elastomer. The porous material may also include one or more additives appropriately selected, depending on the properties desired, from additives that are conventionally used in the polymer industry. In this way, it may contain fillers of soft colors of the silica, carbonate, clay, clay or kaolin type, plasticizers, inks or pigments, stabilizers such as ultraviolet stabilizing antioxidants, antiozonants, fungicides, bactericides, microencapsulated fragrances, as well as suitable processing aids to facilitate their manufacture, such as thickeners, surfactants, latex coagulants or crosslinking agents, as will be explained below. According to a first preferred embodiment of the porous material, according to the invention, the proportion of the total mass of the fibers (cellulose fibers and, optionally, synthetic fibers) with the mass of the elastomer that is present in this material, is between 2 and 0.2 and preferably between 1.5 and 0.3. According to the invention, the porous material can have cells all of the same size or of approximately the same size. However, it is preferred that the size of these cells be heterogeneous and distributed over a wide distribution in order to form a network of microcavities and macrocavities within the porous material, whose network can increase the water absorption capacity of this material , as well as its ability to contain water before twisting (so that water does not drip from it due to the effect of gravity) and to give it, in addition, the necessary flexibility to allow it to twist easily. According to another preferred embodiment of the porous material, according to the invention, it has a relative density of between 0.03 and 0.08 and a water absorption capacity of between 900 and 1200 percent. According to yet another advantageous embodiment of the porous material, according to the invention, this? It also has a tensile strength of at least 0.1 mPa. In this way, the porous material according to the invention has many advantages: in addition to having a high absorbency, it can retain the water that was absorbed during all the time it is desired that it is not actively removed from it, while the released under the effect of manual twisting. In addition, it has a high cleaning capacity. In addition, it is flexible, facilitating its management, and resilient, allowing it to take its initial form after each cleaning operation. Additionally, it has mechanical properties, especially tensile strength properties, which are extremely unsatisfactory. Accordingly, the porous material according to the invention is particularly well suited for? used in the construction of sponges, and especially sponges bath and sponges to clean surfaces. To do this, the material preferably has a thickness of between 1 and 15 centimeters, particularly preferably between 2 and 5 centimeters, in order to make the handling of these sponges easier. The subject of the present invention is also a process for preparing a porous material as defined above, which is characterized in that it comprises: a) preparing a mixture comprising at least P cellulose fibers and an elastomer; 5 b) forming this mixture; c) incorporating into the mixture, during step a) or step b), an agent that can confer, possibly by means of a change of physical state, a honeycomb structure in the product obtained in step b) and , if required; D) apply, to the product obtained in step b), a treatment that may cause the change of the physical state of the agent and / or the cross-linking of the product. According to a first preferred method for implementing the process according to the invention, the elastomer is a crosslinkable elastomer which is used in the form of a latex and the process comprises: a) dispersing the cellulose fibers in an aqueous phase, mix this dispersion with the latex in the presence of > a crosslinking system that is selected properly, and incorporate the pieces of ice in the resulting mixture; b) forming this mixture by freezing; and c) heat the product that results from the freezing, with the aim of melting the pieces of ice that it contains, to cross it and to dry it. Thus, in this first preferred method for implementing the process according to the invention, the agent that can confer a honeycomb structure on the porous material, consists of pieces of ice which, for The means to be incorporated into the dispersion mixture of 5 cellulose fibers / latex before being frozen, will form, while this mixture is freezing and coagulating consecutively, the locations of the cells by the position they occupy within that mixture. The subsequent heating of the product after the operation of freezing, which simultaneously melts the pieces of ice that it contains and reticles and dries that product, makes possible the formation of a honeycomb structure. In fact, the shape and size of the pieces of ice that are used determine those of the cells of the material porous. Also, these pieces of ice are chosen depending on the honeycomb structure that is desired to be given to the porous material. In this way, it is possible to use, depending on the case, ice pieces of irregular shape, such as crushed ice, I which is obtained for example by grinding or grinding, or, On the other hand, pieces of ice on a regular basis, such as spherical or ovoid pieces of ice, which are obtained by molding, granulation or any other process, or mixtures of these pieces. In addition, although it is generally preferred to use a mixture of pieces of ice that have different sizes with the In order to obtain a porous material with a wide distribution of cell sizes, it is also possible to use pieces of ice having the same or approximately the same size, if it is desired that the cells of the porous material are # all of about the same size. In accordance with a convenient way to realize this first preferred method of implementation, the ice pieces that are incorporated within the cellulose fiber / latex dispersion mixture are composed of a mixture of approximately spherical pieces of ice having 10 diameters. that fluctuate between 0.1 and 10 millimeters. The proportion of the mass of dry matter present in the dispersion mixture of cellulose fibers / latex with the mass of pieces of ice that are incorporated into the mixture determines the final density of the porous material. Therefore, they are conveniently selected according to the density desired to be given to the porous material. In this way, by way of example, excellent results have been obtained by means of preparing, in accordance with? this first preferred method of implementation, materials porous having a dry mass ratio of cellulose fibers with that of the elastomers close to 1: - by mixing a dispersion of cellulose fibers having a fiber concentration of about 10 percent, with a latex having a dry elastomer content of approximately 42 percent, in proportions that make it possible to obtain, taking into account the additives that are added to them (crosslinking system and, optionally, coagulants, fillers, inks, etc.), %! a proportion of the mass of dry matter with the mass of water 5 which are present in this mixture of about 0.2, before the ice pieces are incorporated; and - by means of incorporating, within this mixture, pieces of ice in a suitable amount to decrease the proportion of the mass of dry matter with the mass of water (which includes the water represented by the pieces of ice) which are present in this mixture, at a value of approximately 0.1. The cellulose fibers can be dispersed in the aqueous phase by introducing these fibers into a mixer that was previously filled with a suitably selected volume of water and subjected to adequate mechanical agitation (which, in general, will be more vigorous between longer cellulose fibers) and > means to maintain this agitation until obtaining a pulp homogeneous. Whichever type of mixer (turbodispersor, planetary mixer, agitator adjusted with a deflocculating blade, etc.) in which this dispersion is made, it is advantageous for this mixer to be equipped with a system that avoids, or at least limits, the heating the dispersion, such as, for example, a system for cooling the walls. According to another convenient way to realize this first preferred method of implementation, the dispersion mixture of cellulose fibers / latex, after the ice pieces have been incorporated, is frozen by cooling this mixture to a temperature of between -10 and -40 ° C and keep it at this temperature for a time between 2 and 5 hours, depending on its thickness. However, it is possible to use lower temperatures, for example about -50 to -60 ° C. The product is heated after it has been frozen by preferably subjecting this product to a temperature of between 100 and 200 ° C by means of a heating device such as a microwave or infrared tunnel, a steam tube, a live steam or hot air autoclave, a forced air or hot air oven or a high frequency oven, or by using several of these devices in succession. It should be noted that, if it is desired that the porous material contain, in addition to the cellulose fibers, synthetic fibers, it is very possible, in accordance with this first preferred method of implementation, to add these synthetic fibers to the cellulose fibers, for example. example by dispersing them together with the latter in the aqueous phase. Similarly, if one wishes to use one or more polymers suitable for use as agents that act as an interconnection between the fibers and the elastomer and / or one or more additives and, in particular, a suitable agent to promote I »the coagulation of the latex during the freezing step 5 (calcium chloride, ammonium chloride, calcium nitrate, etc.), these can be incorporated either within the dispersion of cellulose fibers or into the latex, or inside of its mixture as obtained in step a). According to a second preferred method for implementing the process according to the invention, the elastomer is a crosslinkable elastomer, which is used in the form of a latex and the process comprises: a) dispersing the cellulose fibers in an aqueous phase, mix this dispersion with the latex in the presence of a suitably selected crosslinking system and converting the resulting mixture into a foam; b) forming this foam by coagulation; and c) heat the product that results from this > coagulation, with the aim of reticularizing and drying it. In this way, in this second preferred method for implementing the process according to the invention, the agent that can confer a honeycomb structure on the porous material, consists of a gas which, having been introduced into the dispersion mixture of fibers of cellulose / latex, will generate a multitude of bubbles within this mixture and will turn it into a foam. The subsequent coagulation of this foam, by means of causing it to solidify while still maintaining the bubbles that I contains, results in the formation of an interconnected honeycomb structure that is conveniently characterized by a wide distribution of cell sizes. Preferably, the gas is air and this is introduced into the dispersion mixture of cellulose / latex fibers by means of submitting this mixture for a few minutes. to vigorous mechanical agitation, conveniently at 800 to 1200 rpm, for example in a turbodispersor which, here again, can be provided with a suitable system to prevent, or at least limit, the heating of the mixture, such as a system to cool the walls. However, it is It is possible to use a gas other than air, for example an inert gas, for the purpose of performing this foaming operation. As for the speed at which the fiber dispersion mixture is mechanically stirred > cellulose / latex and the duration of this agitation that controls Both the density and the size of the cells of the porous material that was finally obtained, this means that both the density and the size will decrease the more vigorous and prolonged the agitation, the speed and duration of this agitation will be selected so both conveniently in accordance with the properties that are desired to confer to the porous material. According to a first alternative version of this second preferred method of implementation, the coagulation of the foam is obtained by means of freezing it. Conveniently, the freezing is performed by cooling the foam to a temperature of between -10 and -30 ° C and keeping it at this temperature for a time of between 2 and 5 hours, depending on its thickness. According to another alternative version of this second preferred method of implementation, the foam is coagulated by means of thermally sensitizing the latex it contains. This operation of thermal sensitization requires the presence in this foam of a coagulant that can react under the effect of an increase in the temperature of the foam - this means in practice, when the latter is heated - such as an organosiloxane. This coagulant is added to the latex in proportions, preferably, between 0.05 and 0.5 parts by mass per 100 parts of dry mass of the elastomer present in this latex. Conveniently, the latex is coagulated by a thermal sensitization operation by bringing the foam to a temperature of at least 25 ° C, and preferably greater than 35 ° C, for example in a microwave or infrared tunnel. , a steam pipe, a live steam or hot air autoclave, a forced air or hot air oven or a high frequency furnace and by keeping this foam at this temperature for a long enough time to convert it in gel, that is, in the practice, for a time between 1 and 5 hours depending of the thickness of the foam, the nature of the latex and the coagulant, and the amount of coagulant used. According to the invention, coagulation, whether carried out by freezing or by thermal sensitization, is followed by an operation in the which heats the product that results from this coagulation, the purpose of this operation being, in the first case, to thaw, dry and crosslink this product, in the second case, its action is limited to drying and reticularizing it. This heating operation is preferably carried out by means of to subject the product to a temperature between 100 and 200 ° C, again using a heating device of the type comprising a microwave or infrared tunnel, a steam tube, a live steam or hot air autoclave , I a forced air or hot air oven or a high oven , or several of these devices in succession, and by maintaining this temperature for a time between 1 and 5 hours, depending on the case. In practice, if the foam is coagulated by thermal sensitization of the latex, it is possible and even advantageous This coagulation and the drying and crosslinking of the resulting product in a single step and in a single heating device, by placing the foam directly in this device preheated to the temperature L »selected for drying and crosslinking, whereby coagulation is carried out during the rise in the temperature of the foam. In accordance with this second preferred method for implementing the process according to the invention, this also comprises the incorporation, within the dispersion of cellulose fibers, the latex or the mixture thereof, depending on the case: of a suitable surfactant to promote the conversion of the dispersion mixture of cellulose fibers / latex into a foam; as examples of the surfactants that have proven to be particularly useful for implementing the process according to the invention, mention should be made of sulfosuccinates such as those sold under the trademark AEROSOL; when you use that > surfactant is preferably added to the latex before the latter is mixed with the dispersion of cellulose fibers and in proportions of between 2 and 6 parts by mass per 100 parts of dry mass of the elastomer present in this latex; - of a suitable agent to stabilize the foam, once the latter has been formed; this agent may especially be a thickener such as a cellulose ester or ether (hydroxyethylcellulose, hydroxypropylmethylcellulose, etc.); in addition, this agent is conveniently incorporated within the dispersion of cellulose fibers in proportions of between 0.5 I and 4 parts per mass of dry mass [sic] of the elastomer present in the latex; - of a suitable agent to promote the coagulation of the foam when this coagulation is obtained by freezing, of the type of calcium chloride, ammonium chloride or calcium nitrate. By way of example, excellent results have been obtained by preparing, in accordance with this second method for implementation reference, porous materials having a ratio of the dry mass of cellulose fibers to the dry mass of the elastomer, about 0.5 per Means of mixing a dispersion of cellulose fibers having a fiber concentration of between 8 and 15 percent, with a latex having a dry elastomer content of about 55 percent in proportions that make it possible to obtain, taking into account the additives that are added to these (crosslinking system and, optionally, fillers, surfactants, thickeners, coagulants, etc.), a ratio of the mass of the dry matter to the mass of water, which are present in this mixture of approximately 0.3. In this second preferred method for implementing the process according to the invention, it should be mentioned that the cellulose fibers can be dispersed in the aqueous phase under the same conditions as those described I * previously in relation to the first preferred method of implementation. Furthermore, it is also possible, according to this second preferred method of implementation, to add synthetic fibers to the cellulose fibers, for example by dispersing them together with the latter in the aqueous phase, if wishes to use one or more polymers that can be used as agents that act as an interconnect between the fibers and the elastomer and / or a6 or more additives other than those specifically considered above, to incorporate these elements either within the dispersion of fibers cellulose or within the latex or within its mixture as obtained in step a). In accordance with a third preferred method for implementing the process according to the invention, the > elastomer is an elastomer that can be crosslinked or a thermoplastic elastomer that is used in dry form and the process comprises: a) mixing the cellulose fibers with the elastomer, optionally in the presence of a suitably selected crosslinking system, and incorporating one or more agents of blowing into this mixture; b) forming the mixture by extrusion, satin and / or molding and, if necessary; c) heat the product that was formed in this way I with the aim of decomposing the agent or blowing agents that it contains, to expand it and, optionally, to reticularize it. In the context of the present invention, it should be understood that the term "blowing agent" means any agent which, by the decomposition due to the The effect of temperature can release gas and consequently cause the material in which it is found to expand. Thus, in this third preferred method for implementing the process according to the invention, the agent that can confer a honeycomb structure on the porous material, consists of at least one blowing agent which is incorporated into the cellulose fiber / elastomer mixture, before the latter is formed and which, by decomposition, either during the formation of > the mixture or after this training, makes it possible for expand the resulting product and that a honeycomb structure is formed in this product. Preferably, different blowing agents having different decomposition kinetics are incorporated into the mixture of cellulose fibers / elastomer, with the The objective is to obtain a porous material that has a wide distribution of cell sizes. However, it is possible to use only a single blowing agent when it is desired that all the cells of the porous material are of approximately the same size. The blowing agents useful according to the invention can be selected in particular from azo-dicarbonamide, azodiisobutyronitrile, p, p'-oxybis- (benzenesulfonylhydrazide), p-toluenesulfonyl semi-carbazide and p-toluenesulfonyl hydrazide. When the elastomer is a crosslinkable elastomer, it is further advantageous to adjust the expansion and kinetics of the crosslinking of the product after the forming operation, by varying the nature and amount of the crosslinking agents and the agents from blown, so that the expansion is a maximum when the crosslinking is itself a maximum, allowing by the same that this product stabilizes while it is in its state of maximum expansion. > In accordance with a first alternative version of In this third preferred method of implementation, with the elastomer being a crosslinkable elastomer, the mixture of cellulose fibers / elastomer is formed by extrusion at a temperature of between 60 and 80 ° C and then the product which was extruded is heated to a temperature between 120 and 180 ° C, directly by leaving it on the extruder, for example by passing it through a microwave tunnel, or a steam tube, in order to expand and crosslink it. In accordance with another alternative version of this I * third preferred method of implementation, being the elastomer In a thermoplastic elastomer, the mixture of cellulose fibers / elastomer is formed by extrusion at a temperature of between 140 and 180 ° C and the extrudate expands simultaneously as it leaves the die. In accordance with yet another alternative version of this third preferred method of implementation, with the elastomer being a crosslinkable elastomer, the cellulose / elastomer fiber mixture is formed by satin, followed by compression molding, which is performed at a temperature between 120 and 150 ° C and allows the product molded partially reticulate. After demolding, this product is heated to a temperature between 150 and 200 ° C, for example by means of an oven or a hot air autoclave, in order to expand and complete its? reticulation. In accordance with yet another alternative version of this third preferred method of implementation, which applies both in the case where the elastomer is a crosslinkable elastomer, and in the case where it is a thermoplastic elastomer, the fiber mixture The cellulose / elastomer is formed by partially filling an injection mold or transferring the mold and then by means of expanding the mixture and, optionally, crosslinking it simultaneously within the mold, with the aim of filling the latter completely. When the elastomer is an elastomer that can be crosslinked, the mold is preheated, for example at a temperature between 150 and 200 ° C. According to a fourth preferred method for implementing the process according to the invention, the elastomer is a thermoplastic elastomer that is used in a dry form and the process comprises: a) mixing the cellulose fibers with the elastomer; and 'b) forming the mixture by extrusion and incorporating an expanding agent into this mixture while it is being formed. According to a first alternative version of this fourth preferred method of implementation, the blowing agent is water or gas such as propane or Freon, which is introduced into the extruder while the mixture of cellulose fibers / elastomer is being plasticized and spontaneously expands the product that was extruded, as it leaves the die by vaporizing the water or gas it contains. This is made possible, for example, by applying temperature and pressure conditions at the exit of the die, which are suitable to create a thermodynamic imbalance and, consequently, cause the water or gas contained in the product that was extruded, pass V a liquid state to a gaseous state. In accordance with another alternative version of this third preferred method of implementation, the blowing agent consists of one or more blowing agents, which are introduced into the extruder while it is being fed with the mixture of cellulose fibers / elastomer and the product that was extruded spontaneously expands as it leaves the die. In all cases, the extrusion is conveniently carried out at a temperature between 140 and 190 ° C. Whatever the method to implement the According to the invention, this process includes, whenever a crosslinkable elastomer is used, the incorporation of a crosslinking system, which is suitably selected depending on the elastomer and can be used. include, apart from an actual cross-linking agent (sulfur or peroxides), promoters and accelerators of the crosslinking, during the preparation of the cellulose fiber / elastomer mixture. Similarly, whenever this process uses, as the agent that acts as an interconnection between the fibers of Cellulose (and optionally synthetic fibers) and elastomer, a polymer whose crosslinking requires the presence of a specific crosslinking system - which is, for example, the case with polyvinyl alcohols - this Bt includes 1 addition of this system of crosslinking, which here again, may include not only an appropriate crosslinking agent, but also promoters and accelerators of the crosslinking. In addition, whatever the method for implementing the process according to the invention, also includes cut the porous material that was obtained to the sizes and shapes (blocks, plates, sheets, etc.) suitable for the uses for which they were proposed. The objective of the present invention are also sponges characterized in that they comprise a porous material 15 as defined above. These sponges, which can be proposed both for bath surfaces and for cleaning surfaces, preferably have a thickness of between 1 and 15 centimeters, particularly preferably between 1.5 and 10 centimeters and yet of more preference between 2 and 5 centimeters, with the aim of making them easier to handle. In addition, the object of the present invention is household articles, which comprise a spongy element, such as sponge rags, twisting mops, and rubber brushes for cleaning surfaces (floors, walls, mirrors, window panes, etc.), characterized in that the spongy element comprises a porous material as described above. The present invention will be understood more clearly with the help of the rest of the description that follows and which refers to the illustrative embodiments of porous materials, in accordance with the invention and the demonstration of their properties. However, it is not necessary to say that these examples 10 are given only by way of illustrating the subject of the invention and in no way constitute a limitation.

EXAMPLE 1: PREPARATION OF A POROUS MATERIAL FROM A LATEX AND CELLULOSE FIBERS 15 A pulp of long cellulose fibers was prepared in a turbodispersor (from Lódige) by means of dispersing gradually, with vigorous stirring (1200-1500 rpm), 235 grams of cotton lint sheets, which were cut? previously in filaments of a few centimeters in size, in 2255 kilograms of water and by maintaining stirring for approximately 10 minutes. They were emptied onto the pulp of fiber that was prepared in that way, 141 grams of 10 percent aqueous CaCl2 solution (which is intended to promote coagulation of the latex) and the compound is mixed for 1 minute at 1200 - 1500 rpm. Then, with gentle stirring within the compound, 559 grams of a carboxylated butadienacrylonitrile rubber latex having a dry rubber content of 42 percent, containing a vulcanization system which is formed by 1 part of an oxide of zinc, 1 part sulfur and 1 part zinc dibutyldithiocarbamate (one crosslink accelerator and one sulfur donor) per 100 parts dry rubber, followed by 1,359 kilograms of spherical pieces of ice (granulated ice) having a distribution of diameters that fluctuate evenly between 0.1 and 10 millimeters. The resulting mixture is emptied into a mold in order to obtain, in the mold, a mixing depth of approximately 10 centimeters and the mold is placed in a freezer at a temperature of -30 ° C for a minimum of 3. hours. After this period of freezing and after demolding, the frozen block which was obtained in this way is enclosed in a metal support gauze and is placed during F 30 minutes in a live steam autoclave that has a temperature of 140 ° C, so as to melt the pieces of ice it contains, to remove the water that results from this melting and to crosslink the latex, and then it was placed for 3 hours 30 minutes in a forced air oven that has a temperature of 130 ° C in order to dry it. Then it can be cut the resulting porous material to the desired dimensions.

EXAMPLE 2: PREPARATION OF A POROUS MATERIAL FROM A LATEX AND A MIXTURE OF CELLULOSE FIBERS A pulp of long cellulose fibers was prepared in ^ a turbodispersor by means of dispersing gradually, with gentle agitation (300-350 rpm), 117 grams of cotton fluff sheets, which were previously cut into filaments a few centimeters in size, in 1127 kilograms of water. After all the filaments of the sheet were introduced into the water, the agitation at 900 rpm and was maintained for 5 to 10 minutes. Meanwhile, in a planetary mixer, a pulp * of short cellulose fibers was prepared by dispersing, with gentle agitation (300 rpm), 117 grams of ARBOCELL fibers "PC 500 (from Rettenmaier &Sohne) at 1127 kilograms. of water and by continuing the agitation, a homogeneous pulp was obtained.Then, while it was stirred gently, the pulp of long fibers was introduced into the pulp of short fibers that was obtained in this way and was continued with the Stirring for a few minutes, so as to obtain a homogeneous mixture. Added to the 2,490 kilograms of this mixture in the container of a planetary mixer, with gentle agitation, are, in succession: 25 • 141 grams of 10% aqueous CaCl 2 solution; • 559 grams of PERBUNAN® N VT latex (a carboxylated butadiene-acrylonitrile rubber latex sold by Bayer and which (• has a dry rubber content of 42 percent); 5 # 9.4 grams of sulfur, 4.7 grams of zinc diethyldithiocarbamate (ZDEC, a crosslink accelerator and sulfur donor) and 4.7 grams of zinc mercaptobenzothioazole (ZMBT, a crosslink accelerator and sulfur donor) and • 2 kilograms of spherical pieces of ice that 10 have a distribution of diameters that fluctuate uniformly between 0.1 and 10 millimeters. The mézala obtained in this way is immediately emptied into a mold in order to obtain, in this mold, a mixing depth of approximately 10 mm. centimeters and the mold is placed in a freezer, under the same conditions as described in Example 1. After this period of freezing and after demolding, the frozen block was enclosed in a suppressive gauze. metal and was placed for 30 minutes in an autoclave live steam that had a temperature of 140 ° C and then during 3 hours 30 minutes in a forced air oven having a temperature of 120 ° C, as described in Example 1.

EXAMPLE 3: PREPARATION OF A POROUS MATERIAL FROM A LATEX AND A MIXTURE OF CELLULOSE FIBERS AND POLYAMIDE FIBERS L? y After having cut the fluff sheets from cotton in filaments that had a length between approximately 8 millimeters and 1 centimeter by means of a granulator, 141.7 grams of the filaments that were obtained in that way were introduced, 12.3 grams of polyamide fibers (from Le Flockage) and 1,386 kilograms of water within a turbodispersor and the compound was stirred at 850 rpm for 3 minutes. In this way, 1,540 kilograms of a pulp of fiber qufe comprised a mixture of cellulose fibers and polyamide fibers, in which mixture these last fibers represent 8 percent by mass of the total mass of the fibers. fibers. ® In addition, added to the 560 grams of CHEMIGUM latex 248 (a rubber latex of butadienacrylonitrile that sells Goodyear and that has a dry rubber content of 55 per cent) in a tight container with a magnetic stirrer (index 6 of the magnetic stirrer) are, in succession: ® • 12.3 grams of AEROSOL (a Cytec surfactant); and • 49.2 grams of a crosslinking system that was previously prepared by dispersing, in a shaker (de Rayneri) adjusted with a deflocculating blade and with vigorous agitation, 100 grains of sulfur, 50 grams of ZDEC and 50 grams of ZMBT in 200 milliliters of a solution containing methylene-bis- (naphthalene-sodium) at 5 percent (a dispersing agent available with BASF under the reference TAMOL "), and the stirring is continued for several minutes in order to obtain a homogenous mixture, 184.8 grams of a 10% CaCl2 solution and 3.08 grams of CELACOL (hydroxypropylmethylcellulose sold by Courtaulds Chemicals) in succession in a turbodisperser, with gentle agitation, to the fiber pulp that was previously obtained and then the latex was incorporated into the resulting mixture and the compound was stirred at 800 rpm for 5 minutes at way to cause a foam to form, then this foam is expelled from the turbodispersor by means of increasing the agitation at 1000 rpm, and it was collected in a laboratory glass with the objective of emptying it directly into a mold, which is filled to a depth of approximately 6 centimeters. After smoothing the surface of the foam in order to obtain a uniform mold filling depth, the mold was immediately placed in a freezer at a temperature of -20 ° C and kept at this temperature for a minimum of 3 hours. After this period of freezing and after having demold, the frozen block was placed in a forced air oven set at a temperature of 120 ° C and kept in this oven for about 3 hours, so as to dry it (there being a change in the mass of the block after this drying) and to crosslink the latex. After having removed the crust, the porous material that was obtained in that way the desired dimensions.

EXAMPLE 4: PREPARATION OF A POROUS MATERIAL FROM A LATEX, SILICA AND A MIXTURE OF CELLULOSE FIBERS AND POLYAMIDE FIBERS. A porous material according to the invention was obtained by following an operation protocol similar to that described in Example 3 above, with the exception of the following differences: the crosslinking system was prepared by means of Disperse 75 grams of sulfur, 25 grams of ZDEC, 25 grams of ZMBT and 125 grams of zinc oxide in 200 milliliters of a 5% aqueous solution of TAMOL; - before it was introduced into the latex, this crosslinking system was mixed with 250 grams of ULTRASIL ® VN3 (a silica that sells Rhóne-Poulenc) and the compound was milled in a ball mill, in order to obtain a perfect homogenization and, finally; - the foam that was formed by stirring the fiber / latex mixture (including the crosslinking and the silica) in the turbodispersor, while this mixture was continued to stir at a speed of 800 rpm (and not at 1000 rpm as in Example 3).

EXAMPLE 5: PREPARATION OF A POROUS MATERIAL FROM A LATEX, POLYVINYL ALCOHOL AND A MIXTURE OF CELLULOSE FIBERS AND POLYAMIDE FIBERS A porous material according to the invention was obtained by performing an operation protocol similar to that which is described in Example 3, except for the following differences: - the fibers (ie, the 141.7 grams of cotton fluff filaments and the 12.3 grams of polyamide fibers) were dispersed in 1185 kilograms of water, so as to obtain 1,338 kilograms of fiber pulp; } - incorporated within this pulp, in addition to the ® solution of CaCl2, CELACOL and latex, there are 205 grams of an aqueous solution containing 30.8 grams of GOHSENOL (polyvinyl alcohol sold by Nippon Goshei) and then 1.2 grams of RESIMEN * s 3521 (a melamine-formaldehyde resin sold by Monsanto and used here as a cross-linking agent for polyvinyl alcohol) and, finally, 0.6 grams of CYCAT 600 (a disulfonic acid sold by Cytec and serving as an accelerator) of crosslinking for polyvinyl alcohol); and the final mixture (fibers + latex + crosslinking system + polyvinyl alcohol + additives) was stirred at 850 rpm for 5 minutes, so as to form a foam and this foam was expelled from the turbodispersor by means of increasing the speed at which stirred this mixture at 950 rpm.

EXAMPLE 6: PREPARATION OF A POROUS MATERIAL FROM A LATEX, A VINYL ADHESIVE AND A MIXTURE OF CELLULOSE FIBERS AND POLYAMIDE FIBERS A porous material according to the invention was also obtained by following an operating protocol similar to that described in Example 5, but by replacing the polyvinyl alcohol and its crosslinking system with 30 grams of a vinyl adhesive (from Sader).

EXAMPLE 7: PREPARATION OF A POROUS MATERIAL FROM 15 LATEX, CALCIUM CARBONATE AND CELLULOSE FIBERS A pulp of cellulose fibers was prepared in a turbodispersor, by dispersing 209.8 grams of cotton fluff sheets, which was cut previously in | filaments of approximately 8 millimeters to 1 centimeter in 20 length, in 1615 kilograms of water and stirring the compound at 850 rpm for 3 minutes. This mixture was then filtered to remove the 361 grams of water from it, in order to obtain 1,464 kilograms of a pulp having a cellulose fiber content of 14.3 percent (m / m). ® 25 In addition, added to the 636 grams of CHEMIGUM 6271 latex (a latex of butadienacrylonitrile that sells Goodyear and that had a dry rubber content of 46 percent) in a container fitted with a magnetic stirrer (index 6 of the magnetic stirrer) are, in succession: "58.6 grams of a crosslinking system that was previously prepared by means of dispersing, in an agitator (from Rayneri) adjusted with a deflocculating and vigorously stirred blade, 47 grams of sulfur, 35 grams of ZDEC and 117.5 grams of zinc oxide in 200 milliliters of a solution containing 5 percent TAMOL ®; • 49.2 grams of a 60 percent aqueous solution of CaCO3 (HYDROCARB® from OMYA); and • 12.3 grams of a 5 percent aqueous solution of coagulant HANSA 4710 (an organosiloxane sold by Goldschmitt Group), and stirring was continued for several minutes, in order to obtain a homogeneous mixture. ® 2.9 grams of CELACOL was added and then the latex in a turbodisperser to the fiber pulp that was previously obtained and the compound was stirred at 850 rpm for 5 minutes in order to obtain a foam. This foam was then expelled from the turbodispersor by means of continuous stirring. 850 rpm and was collected in a laboratory beaker with the aim of emptying it directly into a mold, which was filled to a depth of approximately 6 centimeters.

After matching the surface of the foam in order to obtain a uniform mold filling depth, the mold was immediately placed in a forced air oven at a temperature of 120 ° C and kept in this oven for about 6 hours, as a way to coagulate the foam, as well as to dry the product that resulted from this coagulation and to crosslink the latex. After removing the crust, the porous material could be cut to the desired dimensions.

PROPERTIES OF POROUS MATERIALS OF CONFORMITY WITH THE INVENTION The properties of the porous materials according to the invention were evaluated by determining: - their relative density; - its water absorption capacity: - its water containment capacity after manual twisting; - its resistance to tension; and - its cleaning capacity. The relative density was determined by taking the ratio (d) of the density of the porous materials with the density of the water. The water absorption capacity was determined by weighing the porous materials when they were perfectly dry and after immersing them in a volume of water, and then taking the proportion (A) according to the formula: A = mass after immersion in water - dry mass x 100 dry mass while the capacity of water containment after manual twisting was determined by weighing these same porous materials, after vigorous manual twisting, and taking the ratio (R) according to the formula : R = mass after immersion in water - mass after manual twisting x 100 dry mass With respect to the tensile strength, this was determined by means of extracting test pieces, which measured between 5 and 6 centimeters in length, between 2.5 and 3.5 centimeters in width and between 1.5 and 2.5 centimeters in thickness and which were prepared by means of cutting the porous materials that were to be tested, by means of an electronic voltage tester set at 300 millimeters / minute, until they broke. Finally, the cleaning capacity was evaluated by the presence or absence of traces of water on a surface that was previously moistened, after having cleaned this surface with these porous materials. By way of example, in Table 1 below, the results obtained on the porous materials prepared according to Examples 1, 2, 3, 4 and 5 - and which are hereinafter referred to as Material are given. 1, [• Material 2, Material 3, Material 4 and Material 5.

TABLE 1 ND Not Determined The invention is not limited in any way to the modalities that have been described explicitly: on the contrary, it covers all the variants that could be > '20 occur to a person skilled in the art, without departing from the context or scope of the present invention.

Claims (7)

1. Porous material comprising a mixture of cellulose fibers and at least one elastomer, 5 characterized in that it has: - a honeycomb structure that is formed by cells whose size is between 0.1 and 10 millimeters; a relative density between 0.03 and 0.1; - a water absorption capacity of at least 10 750 per cent; and - a water containment capacity, after the Manuai twist, of less than 100 percent.

2. The porous material according to claim 1, characterized in that it comprises fibers of 15 cellulose which have been previously submitted to an adequate treatment to promote their kinking within the elastomer.

3. The porous material in accordance with the > Claim 2, characterized in that it comprises fibers of 20 cellulose which have previously been subjected to fibrillation.

4. The porous material according to any of claims 1 to 3, characterized in that the elastomer is selected from rubbers of Polybutadiene, butadiene-styrene copolymers, polyurethane copolymers. 8. The porous material according to any of claims 7, characterized in that it comprises one or more additives that are selected from soft-colored fillers, plasticizers, inks or pigments, stabilizers such as antioxidants, UV stabilizers, antiozonants. , fungicides, bactericides, microencapsulated fragrances, thickeners, surfactants, latex coagulants, and crosslinking agents. 9. The porous material according to any of claims 1 to 8, characterized in that the ratio of the total mass of the fibers to the mass of the elastomer that are present in this material is between 2 and 0.2 and preferably between 1.5 and 0.3. 10. The porous material according to any of claims 1 to 9, characterized in that it has a relative density of between 0.03 and 0.08 and a water absorption capacity of between 900 and 1200 percent. 11. The porous material in accordance with 20 any of claims 1 to 10, characterized in that it has a tensile strength of at least 0.1 MPa. The process for preparing a porous material according to any of Claims 1 to 11, characterized in that it comprises: a) preparing a mixture comprising at least cellulose fibers and an elastomer; b) forming this mixture; c) incorporating into the mixture, during step a) or step b), an agent that can confer, possibly by means of a change in physical state, a honeycomb structure in the product obtained in step b) and, if necessary; d) applying, to the product obtained in step b), a treatment that may cause the change of physical state of that agent and / or the cross-linking of the product. 13. The process according to the claim 12, characterized in that the elastomer is a crosslinkable elastomer, which is used in the form of a latex and because it comprises: a) dispersing the cellulose fibers in an aqueous phase, mixing this dispersion with the latex in the presence of a properly selected crosslinking system and incorporating pieces of ice into this mixture; b) forming the mixture by freezing; and c) heat the product that resulted from the freezing in order to melt the pieces of ice that it contains, crosslink it and dry it. 14. The process according to the claim 13, characterized in that the pieces of ice that were incorporated into the dispersion mixture of cellulose fibers / latex, consist of a mixture of pieces 48 17, characterized in that the conversion of the dispersion mixture of cellulose fibers / latex into a foam, is carried out by subjecting this mixture to mechanical agitation. 19. The process according to claim 17 or claim 18, characterized in that the coagulation of the foam is obtained by means of freezing it. 20. The process according to claim 19, characterized in that the foam is frozen by cooling the foam to a temperature between -10 and -30 ° C. 21. The process according to the claim 17 or Claim 18, characterized in that the foam is coagulated by means of thermally sensitizing the latex it contains. 22. The process according to claim 21, characterized in that the process includes the addition, during step a), of a coagulant that can react under the effect of an increase in temperature and because the foam coagulates by carrying the latter at a temperature of at least 25 ° C and preferably greater than 35 ° C. 23. The process according to any of claims 17 to 22, characterized in that the product resulting from the coagulation is heated by means of subjecting the product to a temperature of between 100 and 200 ° C. 24. The process according to any of claim 17 to 23, characterized in that it includes the addition, during step a), of a surfactant and / or a foam stabilizer and / or a latex coagulant. 2

5. The process according to claim 12, characterized in that the elastomer is a crosslinkable elastomer or a thermoplastic elastomer, which is used in dry form and because it comprises: a) mixing the cellulose fibers with the elastomer, optionally in the presence of a suitably selected crosslinking system, and incorporating one or more blowing agents into this mixture; b) forming the mixture by extrusion, satin and / or molding and, if necessary; c) heating the product that was formed in that way in order to decompose the blowing agent or agents it contains, to expand it and, optionally, to crosslink it. 2

6. The process according to claim 25, characterized in that the different blowing agents having different decomposition kinetics are incorporated into the dispersion mixture of cellulose fibers / elastomer, in order to obtain a porous material with a 'wide distribution of cell sizes. 2

7. The process according to claim 25 or claim 26, characterized in that the elastomer being a crosslinkable elastomer, the mixture of 51 12, characterized in that the elastomer is a thermoplastic elastomer which is used in a dry form. and because it comprises: a) mixing the cellulose fibers with the elastomer; and b) forming the mixture by extrusion and incorporating an expanding agent into this mixture while it is being formed. 32. The process according to claim 31, characterized in that the blowing agent is water or gas, which is introduced into the extruder while the mixture of cellulose fibers / elastomer is being plasticized and the extruded product is expanded from Spontaneously as you leave the die by vaporizing the water or the gas it contains. 33. The process according to claim 31, characterized in that the blowing agent is one or more blowing agents which are introduced into the extruder while it is being fed with the mixture of cellulose fibers / elastomer and the extruded product. It expands simultaneously as it leaves the die. 34. The process according to any of claims 31 to 33, characterized in that the extrusion is carried out at a temperature between 140 and 190 ° C. 35. Sponges, characterized in that they comprise 52 a porous material according to any of Claims 1 to 11. 36. Household articles comprising a porous element, such as sponge rags, squeeze mops and rubber brushes for cleaning surfaces , characterized in that the porous element comprises a porous material according to any of Claims 1 to 11.